Few discussions of the ethics of mitochondrial ‘replacement’ techniques have drawn significant ethical distinctions between the two approaches now legal in the U.K. However, Anthony Wrigley, Stephen Wilkinson and John Appleby have together argued that under some circumstances pronuclear transfer (PNT) may be in better ethical standing than maternal spindle transfer (MST). They base their conclusion on what they allege to be different implications of the techniques with respect to non‐identity considerations, which they ground on a version of (...) class='Hi'>origin essentialism. I raise a series of problems for their argument, which have cautionary implications for invocations of origin essentialism that go beyond specialized debates regarding MST and PNT. I argue that (i) origin essentialism is a fragile foundation for non‐identity considerations; (ii) gametic essentialism, which Wrigley et al. believe licenses their claims, is more questionable than origin essentialism; (iii) gametic essentialism does not straightforwardly justify their conclusion; and (iv) their conclusion in fact relies on an especially dubious position that we can call chromosomal origin essentialism. No good reasons have yet been supplied to distinguish PNT from MST on ethical grounds, and one should be wary of basing claims with practical impact on fragile foundations relating to origin essentialism. (shrink)

Discussions on original sin conduced over the last 50 years yield the conclusion that the second half of the 20th century brought about the most far-reaching changes in the perception of original sin since the times of St. Augustine. In spite of these profound changes, the matter in question continues to give rise to controversies. Thus, Alfred Vanneste considers the omission of monogenism in the Catechism of the Catholic Church 2 to be a gross oversight on the part of the (...) drafting committee. During deliberations on the transformations of modern culture, an issue may arise, which implied that the notion of human nature encumbered with the weakness of original sin is one of the truths of highest empirical confirmation. It should be noted, however, that an immense diversity of standpoints In expressing his truth exist. (shrink)

Discussions on original sin conduced over the last 50 years yield the conclusion that the second half of the 20th century brought about the most far-reaching changes in the perception of original sin since the times of St. Augustine. In spite of these profound changes, the matter in question continues to give rise to controversies. Thus, Alfred Vanneste considers the omission of monogenism in the Catechism of the Catholic Church 2 to be a gross oversight on the part of the (...) drafting committee. During deliberations on the transformations of modern culture, an issue may arise, which implied that the notion of human nature encumbered with the weakness of original sin is one of the truths of highest empirical confirmation. It should be noted, however, that an immense diversity of standpoints In expressing his truth exist. (shrink)

Mitochondrial/nuclear transfer (M/NT) to avoid the transmission of serious mitochondrial disease raises complex and challenging ethical, legal and social issues (ELSI). In February 2015, the United Kingdom became the first country in the world to legalize M/NT, making the heated debate surrounding this technology even more relevant. This critical interpretive review identified 95 relevant papers discussing the ELSI of M/NT, including original research articles, government-commissioned reports, editorials, letters to editors and research news. The review presents and synthesizes the (...) arguments present in the literature in relation to the most commonly raised themes: terminology; identity, relationships and parenthood; potential harm; reproductive autonomy; available alternatives; consent; impact on specific interest groups; resources; “slippery slope”; creation, use and destruction of human embryos; and beneficence. The review concludes by identifying those ELSI that are specific to M/NT and by calling for follow-up longitudinal clinical and psychosocial research in order to equip future ELSI debate with empirical evidence. (shrink)

Mitochondrial function and biogenesis depend on the transport of a large variety of proteins, ions, and metabolites across the two surrounding membranes. While several specific transporters are present in the inner membrane, transport processes across the outer membrane are less understood. Recent studies reveal that the number of outer membrane channels and their transport mechanisms are more diverse than originally thought. Four protein‐conducting channels promote transport of distinct sets of precursor proteins across and into the outer membrane. The voltage‐dependent (...) anion channel (VDAC) forms the major channel for small hydrophilic molecules. In addition, three channels with yet unknown substrate specificity exist in the outer membrane. In this review, we outline the emerging functional diversity, selectivity, and regulation of mitochondrial outer membrane channels. The presence of several channel‐forming proteins challenges the traditional view that the outer membrane forms an unspecific size‐exclusion filter for the flux of small hydrophilic molecules. (shrink)

Molecular genetic data have greatly improved our ability to test hypotheses about human evolution. During the past decade, a large amount of nuclear and mitochondrial data have been collected from diverse human populations. Taken together, these data indicate that modern humans are a relatively young species. African populations show the largest amount of genetic diversity, and they are the most genetically divergent population. Modern human populations expanded in size first on the African continent. These findings support a recent African (...) origin of modern humans, but this conclusion should be tempered by the possible effects of factors such as gene flow, population size differences, and natural selection. BioEssays 20:126–136, 1998. © 1998 John Wiley & Sons, Inc. (shrink)

Uncoupling proteins (UCPs) regulate mitochondrial function, and thus cellular metabolism. Angiotensin‐converting enzyme (ACE) is the central component of endocrine and local tissue renin–angiotensin systems (RAS), which also regulate diverse aspects of whole‐body metabolism and mitochondrial function (partly through altering mitochondrial UCP expression). We show that ACE expression also appears to be regulated by mitochondrial UCPs. In genetic analysis of two unrelated populations (healthy young UK men and Scandinavian diabetic patients) serum ACE (sACE) activity was significantly higher (...) amongst UCP3‐55C (rather than T) and UCP2 I (rather than D) allele carriers. RNA interference against UCP2 in human umbilical vein endothelial cells reduced UCP2 mRNA sixfold (P < 0·01) whilst increasing ACE expression within a physiological range (<1·8‐fold at 48 h; P < 0·01). Our findings suggest novel hypotheses. Firstly, cellular feedback regulation may occur between UCPs and ACE. Secondly, cellular UCP regulation of sACE suggests a novel means of crosstalk between (and mutual regulation of) cellular and endocrine metabolism. This might partly explain the reduced risk of developing diabetes and metabolic syndrome with RAS antagonists and offer insight into the origins of cardiovascular disease in which UCPs and ACE both play a role. (shrink)

Accumulating data suggest that the eukaryotic cell originated from a merger of two prokaryotes, an archaeal host and a bacterial endosymbiont. However, since prokaryotes are unable to perform phagocytosis, the means by which the endosymbiont entered its host is an enigma. We suggest that a predatory or parasitic interaction between prokaryotes provides a reasonable explanation for this conundrum. According to the model presented here, the host in this interaction was an anaerobic archaeon with a periplasm‐like space. The predator was a (...) small (facultative) aerobic α‐proteobacterium, which penetrated and replicated within the host periplasm, and later became the mitochondria. Plausible conditions under which this interaction took place and circumstances that may have led to the contemporary complex eukaryotic cell are discussed. (shrink)

This article addresses the child’s right to know their genetic origins in mitochondrial donation. It focuses on the UK’s public debate on mitochondrial replacement techniques and examines the claims-making activities that shaped the donor information regulations. During the public consultation, downplaying the significance of the mitochondria helped distinguish mitochondria donors from gamete donors and determine their relational status with the resulting child. As a result, according to the Mitochondrial Donation regulations, mitochondria donors, unlike gamete donors, will not (...) be required to be identifiable to the resulting child. I argue that, in the UK, similar to donor conception, public understanding of mitochondrial donation is shaped by a “calculus of genes”: simplified accounts of how genes determine the resulting child’s characteristics and identity. While the donor conception regulations ascribe social meaning to the passage of genes, the mitochondria regulations strip the social meaning away from the donation based on the assumption that the genetic contribution made by the donor is quantitatively insignificant in influencing the identity of the resultant offspring. The nature of the genetic material itself should not be considered as a privileged standpoint from which to decide on social meaning of the donation or the rights attached to it. (shrink)

A marked feature of eukaryotic programmed cell death is an early drop in mitochondrial transmembrane potential. This results from the opening of permeability transition pores, which are composed of adenine nucleotide translocators and mitochondrial porins. The latter share striking similarites with bacterial porins, (including down‐regulation of their pore size by purine nucleotides), suggesting a common origin. The porins of some invasive bacteria play a crucial role during their accommodation inside the host cell and this co‐existence resembles the (...) endosymbiotic origin of mitochondria. The above observations suggest that early in eukaryotic evolution, former invaders may have used porin‐type channels to enter their host and to induce its death when the levels of its cytoplasmic purine nucleotides were dropped. The appearance of adenosine nucleotide translocators in the primitive eukaryotes, which permitted usage of the oxidative metabolism of the invaders, provided the basis for the permeability transition phenomena, now linked to the apoptotic process. Bcl‐2‐type molecules, being able to modulate the permeability transition pores by interaction with adenosine nucleotide translocators, may have played an essential role in conferring a means of controlling apoptosis. (shrink)

Both religion and science provide powerful images of human origins and human nature. Often these images are seen as incompatible or irreconcilable, with the religious image generally marginalized vis-à-vis the scientific image. Recent genetic studies into human origins, especially in terms of common cellular features like the mitochondrion from females and the Y-chromosome from males, provide evidence for common ancestors called mitochondrial Eve and Y-chromosomal Adam. The aim of this paper is to expound upon the Judeo-Christian and western scientific (...) images of humanity with respect to human origins and human nature, especially in terms of possible reconciliation of the two images. (shrink)

The cryptomonads and chlorarachniophytes are two unicellular algal lineages with complex cellular structures and fascinating evolutionary histories. Both groups acquired their photosynthetic abilities through the assimilation of eukaryotic endosymbionts. As a result, they possess two distinct cytosolic compartments and four genomes—two nuclear genomes, an endosymbiont‐derived plastid genome and a mitochondrial genome derived from the host cell. Like mitochondrial and plastid genomes, the genome of the endosymbiont nucleus, or ‘nucleomorph’, of cryptomonad and chlorarachniophyte cells has been greatly reduced through (...) the combined effects of gene loss and intracellular gene transfer. This article focuses on the structure, function, origin and evolution of cryptomonad and chlorarachniophyte nucleomorph genomes in light of recent comparisons of genome sequence data from both groups. It is now possible to speculate on the reasons that nucleomorphs persist in cryptomonads and chlorarachniophytes but have been lost in all other algae with plastids of secondary endosymbiotic origin. BioEssays 29:392–402, 2007. © 2007 Wiley Periodicals, Inc. (shrink)

The origin of the eukaryotic cell nucleus and the selective forces that drove its evolution remain unknown and are a matter of controversy. Autogenous models state that both the nucleus and endoplasmic reticulum (ER) derived from the invagination of the plasma membrane, but most of them do not advance clear selective forces for this process. Alternative models proposing an endosymbiotic origin of the nucleus fail to provide a pathway fully compatible with our knowledge of cell biology. We propose (...) here an evolutionary scenario that reconciles both an ancestral endosymbiotic origin of the eukaryotic nucleus (endosymbiosis of a methanogenic archaeon within a fermentative myxobacterium) with an autogenous generation of the contemporary nuclear membrane and ER from the bacterial membrane. We specifically state two selective forces that operated sequentially during its evolution: (1) metabolic compartmentation to avoid deleterious co‐existence of anabolic (autotrophic synthesis by the methanogen) and catabolic (fermentation by the myxobacterium) pathways in the cell, and (2) avoidance of aberrant protein synthesis due to intron spreading in the ancient archaeal genome following mitochondrial acquisition and loss of methanogenesis. BioEssays 28: 525–533, 2006. © 2006 Wiley Periodicals, Inc. (shrink)

Animal and plant species exhibit an astonishing diversity of sexual systems, including environmental and genetic determinants of sex, with the latter including genetic material in the mitochondrial genome. In several hermaphroditic plants for example, sex is determined by an interaction between mitochondrial cytoplasmic male sterility (CMS) genes and nuclear restorer genes. Specifically, CMS involves aberrant mitochondrial genes that prevent pollen development and specific nuclear genes that restore it, leading to a mixture of female (male‐sterile) and hermaphroditic individuals (...) in the population (gynodioecy). Such a mitochondrial‐nuclear sex determination system is thought to be rare outside plants. Here, we present one possible case of CMS in animals. We hypothesize that the only exception to the strict maternal mtDNA inheritance in animals, the doubly uniparental inheritance (DUI) system in bivalves, might have originated as a mitochondrial‐nuclear sex‐determination system. We document and explore similarities that exist between DUI and CMS, and we propose various ways to test our hypothesis. (shrink)

Metagenomics bears upon all aspects of microbiology, including our understanding of mitochondrial and eukaryote origin. Recently, ribosomal protein phylogenies show the eukaryote host lineage – the archaeal lineage that acquired the mitochondrion – to branch within the archaea. Metagenomic studies are now uncovering new archaeal lineages that branch more closely to the host than any cultivated archaea do. But how do they grow? Carbon and energy metabolism as pieced together from metagenome assemblies of these new archaeal lineages, such (...) as the Deep Sea Archaeal Group (including Lokiarchaeota) and Bathyarchaeota, do not match the physiology of any cultivated microbes. Understanding how these new lineages live in their environment is important, and might hold clues about how mitochondria arose and how the eukaryotic lineage got started. Here we look at these exciting new metagenomic studies, what they say about archaeal physiology in modern environments, how they impact views on host‐mitochondrion physiological interactions at eukaryote origin. (shrink)

While mitochondrial sequences can be used to probe the time and place of the mitochondrial ‘Eve,’ nuclear genes can be used to ask a slightly different question: when did humans (members of the genus Homo) or their hominid precursors (the hominids) first leave Africa and fan out over Asia and Europe? If they did so recently, it seems likely that there was a recent African origin of our species, Homo sapiens, rather than multiple origins in various parts (...) of the Old World. A recent paper(1) uses minisatellite data to make the argument that the departure from Africa happened very recently indeed. An alternative explanation for the data is that there was no single and irreversible departure from Africa, but that some peoples migrated back and forth between Africa and the rest of the Old World over the last few tens of thousands of years. For this and other reasons, putting a single date on the farewell to Africa remains problematical. (shrink)

Recently, constructive neutral evolution has been touted as an important concept for the understanding of the emergence of cellular complexity. It has been invoked to help explain the development and retention of, amongst others, RNA splicing, RNA editing and ribosomal and mitochondrial respiratory chain complexity. The theory originated as a welcome explanation of isolated small scale cellular idiosyncrasies and as a reaction to ‘overselectionism’. Here I contend, that in its extended form, it has major conceptual problems, can not explain (...) observed patterns of complex processes, is too easily dismissive of alternative selectionist models, underestimates the creative force of complexity as such, and – if seen as a major evolutionary mechanism for all organisms – could stifle further thought regarding the evolution of highly complex biological processes. (shrink)

A central issue in paleoanthropology is whether modern humans emerged in a single geographic area and subsequently replaced the preexisting people in other areas. Although the study of human mitochondrial DNAs supported this single‐origin and complete‐replacement model, a recent paper1 argues that humans expanded out of Africa more than once and regionally interbred. However, both the genetic antiquity and the impact of the African contribution to modern Homo sapiens are so great as to view Africa as a central (...) place of human evolution. Despite the possibility that out‐of‐Africa H. sapiens interbred with other populations, this evidence is more consistent with the uniregional hypothesis than the multiregional hypothesis of modern human origins. BioEssays 24:871–875, 2002. © 2002 Wiley Periodicals, Inc. (shrink)

Gene expression activity is heterogeneous in a population of isogenic cells. Identifying the molecular basis of this variability will improve our understanding of phenomena like tumor resistance to drugs, virus infection, or cell fate choice. The complexity of the molecular steps and machines involved in transcription and translation could introduce sources of randomness at many levels, but a common constraint to most of these processes is its energy dependence. In eukaryotic cells, most of this energy is provided by mitochondria. A (...) clonal population of cells may show a large variability in the number and functionality of mitochondria. Here, we discuss how differences in the mitochondrial content of each cell contribute to heterogeneity in gene products. Changes in the amount of mitochondria can also entail drastic alterations of a cell's gene expression program, which ultimately leads to phenotypic diversity. (shrink)

The most common form of the CO2‐fixing enzyme rubisco is a form I enzyme, heretofore found universally in oxygenic phototrophs (cyanobacteria and plastids) and widely in proteobacteria. Two groups(1–4), however, now report that in dinoflagellate plastids the usual form I rubisco has been replaced by the distantly related form II enzyme, known previously only from anaerobic proteobacteria. This raises the important question of how such an oxygensensitive rubisco could function in an aerobic organism. Moreover, the dinoflagellate rubisco has unusual molecular (...) properties: it is encoded as a polyprotein, by nuclear (rather than plastid) genes, and these genes contain noncanonical spliceosomal introns. The nuclear location and alphaproteobacterial affinity of dinoflagellate rubisco genes hint at a possible mitochondrial origin and highlight the extraordinary richness of lateral gene transfers, both between and within organisms, that have occurred during rubisco evolution. (shrink)

We use genomic information to tell us stories of evolutionary origins. But what does it mean when different genomes report wildly different accounts of lineage history? This genomic “discordance” can be a consequence of a fascinating suite of natural history and evolutionary phenomena, from the different inheritance mechanisms of nuclear versus cytoplasmic (mitochondrial and plastid) genomes to hybridization and introgression to horizontal transfer. Here, we explore how we can use these distinct genomic stories to provide new insights into the (...) maintenance of sexual reproduction, one of the most important unanswered questions in biology. We focus on the strikingly distinct nuclear versus mitochondrial versions of the story surrounding the origin and maintenance of asexual lineages in Potamopyrgus antipodarum, a New Zealand freshwater snail. While key questions remain unresolved, these data inspire multiple testable hypotheses that can be powerfully applied across a broad range of taxa toward a deeper understanding of the causes and consequences of mitonuclear discordance, the maintenance of sex, and the origin of new asexual lineages. (shrink)

Recent research into human origins has largely focused on deducing past events and processes from current patterns of genetic variation. Some human genes possess unexpectedly low diversity, seemingly resulting from events of the late Pleistocene. Such anomalies have previously been ascribed to population bottlenecks or selection on genes. For four species of matrilineal whale, evidence suggests that cultural evolution may have reduced the diversity of genes which have similar transmission characteristics to selective cultural traits, through a process called cultural hitchhiking. (...) Cultural evolution is characteristic of human societies and so should be considered as a potential determinant of human genetic diversity. A stochastic simulation of gene and cultural dynamics in an array of hunter-gatherer tribes shows that cultural selection has the potential to severely reduce genetic diversity if: inter-tribe gene flows are reasonably low (<~0.6-15 genes/tribe/generation); cultural evolution changes fitness by >~0.3-3%/generation; and fitness is changed more by cultural innovation within a tribe than cultural assimilation from neighboring tribes. Thus cultural hitchhiking may explain low diversity and short coalescence times in mitochondrial and, especially, Y-linked human genes. (shrink)

Of two contending models for eukaryotic evolution the “archezoan“ has an amitochondriate eukaryote take up an endosymbiont, while “symbiogenesis“ states that an Archaeon became a eukaryote as the result of this uptake. If so, organelle formation resulting from new engulfments is simplified by the primordial symbiogenesis, and less informative regarding the bacterium‐to‐mitochondrion conversion. Gradualist archezoan visions still permeate evolutionary thinking, but are much less likely than symbiogenesis. Genuine amitochondriate eukaryotes have never been found and rapid, explosive adaptive periods characteristic of (...) symbiogenetic models explain this. Mitochondrial proteomes, encoded by genes of “eukaryotic origin“ not easily linked to host or endosymbiont, can be understood in light of rapid adjustments to new evolutionary pressures. Symbiogenesis allows “expensive” eukaryotic inventions via efficient ATP generation by nascent mitochondria. However, efficient ATP production equals enhanced toxic internal ROS formation. The synergistic combination of these two driving forces gave rise to the rapid evolution of eukaryotes.Also watch the Video Abstract. (shrink)

This special issue examines the diverse realities created by the intersection of emerging technologies, new scientific knowledge, and the human being. It engages with two key questions: how is the human being shaped and constructed in new ways through advances in science and technology? and how might these new ways of imagining the subject shape present and future human rights law and practice? The papers examine a variety of scientific technologies—personalized medicine and organ transplant, mitochondrial DNA replacement, and scaffolds (...) and regenerative medicine—and their implications for our conceptualization of the human subject. Each is then followed by a commentary that both brings to light new dimensions of the original paper and presents a new theoretical take on the topic. Together these papers offer a serious challenge to the vision of the human subject at the root of human rights law. Instead of the autonomous, rational, unique, and physically discrete individual who owns herself and her body, the subject that emerges from the human technology assemblage has physically porous boundaries and a relational self. This depiction of the human being as a relational subject enmeshed in her technoscientific environment requires that we reconceptualize human rights law and practice. (shrink)

On September 27, 2016 people across the world looked down at their buzzing phones to see the AP Alert: “Baby born with DNA from 3 people, first from new technique.” It was an announcement met with confusion by many, but one that polarized the scientific community almost instantly. Some celebrated the birth as an advancement that could help women with a family history of mitochondrial diseases prevent the transmission of the disease to future generations; others held it unethical, citing (...) medical tourism and consequences for the future of the therapy. The child in question was actually born a few months earlier on April 6, 2016, but the research was published a few months later in the October edition of Fertility and Sterility. The mother carries DNA that could have given the baby Leigh Syndrome, a severe neurological disorder characterized by psychomotor regression that typically results in death between ages two and three.[1] Also known as subacute necrotizing encephalomyelopathy, Leigh Syndrome is caused by genetic mutations in mitochondrial DNA, which causes defective oxidative phosphorylation. Because people with this condition cannot re-form ATP, “demyleniation, gliosis, necrosis, spongiosis, or capillary proliferation”[2] can occur, thereby producing bilateral lesions across the central nervous system. The 36-year-old mother previously had four miscarriages and successfully birthed two children, both of whom survived less than six years due to the syndrome. For religious reasons, the mother opted for Spindle Nuclear Transfer instead of Pronuclear Transfer,[3] which many religious organizations oppose because it entails the destruction of fertilized eggs.[4] In Pronuclear Transfer, both the parent and donor egg are fertilized. The parent’s nuclear material is then removed from the egg containing mutated mitochondria and inserted into the fertilized donor egg—from which the original nuclear material has been removed and destroyed. Spindle Nuclear Transfer, on the other hand, removes the mother’s nuclear material from the egg with unhealthy mitochondria, then implants it into a donor’s egg. The newly created egg is then fertilized with the father’s sperm. This Spindle Nuclear Transfer was performed in Mexico by a team of doctors led by Dr. John Zhang, the founder of the New Hope Fertility Center in New York City. In their report, the doctors outline that five oocytes were successfully reconstituted, four of which developed into blastocysts. Only one was euploid: containing 46 XY chromosomes. Researchers then biopsied that blastocyst and found that the transmission rate of maternal mtDNA was, “5.10 ± 1.11% and the heteroplasmy level for 8993T>G was 5.73%.”[5] This indicates that at the blastocyst stage, around five percent of the mitochondria are from the original maternal egg with the mutation for Leigh Syndrome. After birth, they biopsied different tissues and found that they had an average of less than 1.60 ± 0.92% of transmitted mtDNA from the original maternal egg. The baby is reportedly doing well and the team of doctors concluded that “[h]uman oocytes reconstituted by SNT are capable of producing a healthy live birth. SNT may provide a novel treatment option in minimizing pathogenic mtDNA transmission from mothers to their babies."[6] Even when considered theoretically, Spindle Nuclear Transfer is controversial. Many doctors believe that the risks at this stage of research are too great. Dr. Trevor Stammers, a bioethicist at St. Mary’s University in London, points out: “We do not yet have a clear picture of the interaction between nuclear DNA and mitochondria.”[7] Others hold that faulty mitochondrial DNA can still be transferred during the procedure. Still more argue this technology could create problems because of germline modification.[8] Dr. Paul Knoepfler, a cell biologist at the UC Davis School of Medicine, explains: “Since this is uncharted territory and the children born from this technology would have heritable genetic changes, there are also significant unknown risks to future generations.”[9] However, proponents counter these arguments. They say the benefits outweigh the risks, as “mitochondrial replacement techniques [like Spindle Nuclear Transfer] would eliminate maternal transmission of mitochondrial disease… allowing a woman with a family history of mitochondrial diseases to ensure her children would not be affected.”[10] Additionally, experts say that no symptoms will occur if less than 20% of the transferred mitochondrial DNA is faulty.[11] And while opponents see potential germline modification as a problem, advocates answer that this could stop a family history of mitochondrial disease, which they deem a more serious concern. In this case specifically, however, there are more issues at hand. While the team of doctors did eliminate the possibility of germline modification by selecting a male embryo, there are other ethical concerns. Some argue that this case could be described as “medical tourism.” While New Hope Medical Clinic does maintain a branch in Mexico, Dr. Zhang stated that Mexico has “no rules.”[12] It is a country with underdeveloped regulations, making it difficult to confirm that doctors adhere to widely-held medical and ethical standards. Furthermore, while it is highly unlikely that the child will develop Leigh’s Syndrome, Dr. Dietrich Egli of the New York Stem Cell Foundation says the 5% mitochondrial transfer rate indicates that the technique “was not carried out well.”[13] He points to studies of embryos where the rate of mtDNA transfer was almost ten times lower. Spindle Nuclear Transfer is currently legal in the UK,[14] and many are hoping to see it legalized in the US, although Congress currently prohibits the FDA from considering applications that would entail trials in people.[15] While Dr. Zhang’s work is arguably revolutionary, many wonder if the manner in which this study was performed—in Mexico and with a high mitochondrial transfer rate—will impact the technology’s future in the US. Last week, Dr. Zhang presented the report to scientists gathered in Salt Lake City, saying that while science isn’t a race, it is “in a sense, a race for the family to find a cure, to find hope.”[16] Only time will tell if this study set back other families racing and hoping for a cure. References 1. "Leigh Syndrome." Genetics Home Reference, US National Library of Medicine, 25 Oct. 2016. Accessed 26 Oct. 2016. 2. McKusick, Victor A., and Ada Hamosh. "LEIGH SYNDROME; LS." Online Mendelian Inheritance in Man, Johns Hopkins University, 20 Jan. 2016. Accessed 30 Oct. 2016. 3. Zhang, J, H Liu, S Luo, A Chavez-Badiola, and Z Liu. "First live birth using human oocytes reconstituted by spindle nuclear transfer for mitochondrial DNA mutation causing Leigh syndrome." Fertility and Sterility, vol. 106, no. 3, 2016, pp. e375-76. Accessed 30 Oct. 2016. 4. Sample, Ian. "‘Three-parent’ babies explained: what are the concerns and are they justified?" The Guardian, 2 Feb. 2015. Accessed 30 Oct. 2016. 5. Zhang, et al. 6. Ibid. 7. Knapton, Sarah. "Three-parent babies: the arguments for and against." The Telegraph, 3 Feb. 2015. 8. Ibid. 9. Ibid. 10. "Mitochondrial Replacement Therapy FAQs." New York Stem Cell Foundation Research Institute, New York Stem Cell Foundation. Accessed 30 Oct. 2016. 11. Reardon, Sara. "‘Three-parent baby’ claim raises hopes — and ethical concerns." Nature, 28 Sept. 2016. Accessed 30 Oct. 2016. 12. Hamzelou, Jessica. "Exclusive: World’s first baby born with new “3 parent” technique." New Scientist, 27 Sept. 2016. Accessed 30 Oct. 2016. 13. Reardon, Sara. "‘Three-parent baby’ claim raises hopes — and ethical concerns." Nature, 28 Sept. 2016. Accessed 30 Oct. 2016. 14. "3-Person IVF: A Resource Page." Center for Genetics and Society, 24 Oct. 2016. Accessed 30 Oct. 2016. 15. Ritter, Malcolm. "Baby born with DNA from 3 people, first from new technique." Associated Press, 27 Sept. 2016. Accessed 30 Oct. 2016. 16. Chen, Daphne. "Controversy swirls around first three-parent baby." Deseret News, 19 Oct. 2016. Accessed 30 Oct. 2016. Works consulted Swetlitz, Ike. "FDA urged to approve ‘three-parent embryos,’ a new frontier in reproduction." STAT, 3 Feb. 2016. Accessed 30 Oct. 2016. (shrink)

What kind of symbiosis between archaeon and bacterium gave rise to their eventual merger at the origin of the eukaryotes? I hypothesize that conditions favouring bacterial uptake were based on exchange of intermediate carbohydrate metabolites required by recurring changes in availability and use of the two different terminal electron chain acceptors, the bacterial one being oxygen. Oxygen won, and definitive loss of the archaeal membrane potential allowed permanent establishment of the bacterial partner as the proto‐mitochondrion, further metabolic integration and (...) highly efficient ATP production. This represents initial symbiogenesis, when crucial eukaryotic traits arose in response to the archaeon‐bacterium merger. The attendant generation of internal reactive oxygen species (ROS) gave rise to a myriad of further eukaryotic adaptations, such as extreme mitochondrial genome reduction, nuclei, peroxisomes and meiotic sex. Eukaryotic origins could have started with shuffling intermediate metabolites as is still essential today. (shrink)

This chapter explores current and prospective reproductive technologies and some of their likely implications for reproductive and family ethics and policymaking. The technologies discussed include uterus transplants, mitochondrial transfer, ectogenesis, the development of in vitro gametes, and solo reproduction. The chapter considers the impact of these developments on the content of concepts such as 'infertility', 'mother', or 'father'. Another layer to this process of redefinition originates in ongoing socio-cultural changes that shift the focus in parenting from the way in (...) which children have come into the world, to relationships within the family. Considering these scenarios beforehand can help to clarify some of the current challenges in defining and regulating infertility. The chapter therefore aims to raise a number of questions rather than provide answers. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:preface Sometimes, even those of us who have organized our entire lives around the transformative possibilities of Black feminist thought can sit back in wonder at the expansiveness of this intergenerational transnational practice.Thisspecialissuetakesamomenttoimbibewhere we have been, where we are, and where we have yet to journey. The contributors to this special issue on, or more precisely, of Black feminist thought find Black feminist thinking in a wide range of (...) times, places, and forms. Each of the contributors invites us to bear witness in a distinct way to the pushes and pulls of critical engagement with Black feminist thought. Biomythic origin point “mitochondrial eve” brainstorms the archive and admonishes those of us looking back to “be a forest of your own / dreams.” Gladys Bentley sends unrequited texts to... Gladys Bentley. Everything is possible here, even what should never have happened. In If You Can’t Be Free, Be a Mystery: In Search of Billie Holiday, Farah Jasmine Griffin, one of the most dedicated and prolific stewards of Black feminist thought as a liberatory practice, cites Rita Dove’s poem “Canary” to evoke the protective strategies Black women employ to hold something (ourselves, each other) sacred in an unfree world.1 The lineage we participate in through our Black 1. Farah Jasmine Griffin, If You Can’t Be Free, Be a Mystery: In Search of Billie Holiday (New York: Ballantine Books, 2001), 155–56. “Be a Mystery”: (The Infinity of) Black Feminist Thought 8Preface feminist intellectual labor is sacred to us. For generations, even before the name “Black Feminist,” it has existed as a form of love, communion, protest, and prophecy, often far from the spotlight. Nurtured by the warmth of imagination, practices became praxis. Griffin and others have ensured a tradition wherein, to invoke Griffin’s paraphrase of Toni Morrison in her tribute to Nellie McKay, “the mothers may soar and the daughters may know their names.”2 We are some of the daughters. But we are living in times that neither we nor our mothers would hardly recognize. Abolitionist queer Black feminists are topping the New York Times bestseller lists. Our scholars and experts speak on the nightly news. Some of what were once our most marginalized proposals have become policies, funding keywords, and even memes. The Movement for Black Lives, one of the largest and most visible social movements of our time, or any time, explicitly connects its vision to the foundational Combahee River Collective statement. We do this work now in the light of recognition. Masses of people think they know what Black feminism is, and yet, this is not the world that we dreamed. We, the current generation of practicing Black feminist thinkers, are faced with the consequences of Black feminist practice feeling like less of a mystery. We celebrate the legacy our foremothers have made possible, and we must also think creatively, lovingly, and sometimes even cryptically about what this moment can and must mother—or bring into being. It has to bring into being something we cannot describe from here, something we have not yet known. It is exhilaratingly beautiful to look upon what’s been made possible, but we know there is so much more than recognition. Undaunted by a world still hellbent on not caring for or loving us, even as it consumes our insights, theories, and modes of organizing, we create worlds filled with an abundance of joy, affirmation, and ingenuity. It is from this robust, ancestral practice of world-making that this special issue emerges. The pieces found here provide insight into one of the most dynamic aspects of Black feminist thought: its generative power. The range of topics included in this special issue encapsulates the breadth of this interdisciplinary, transnational, multimodal, and 2. Farah Jasmine Griffin, “That the Mothers May Soar and the Daughters May Know Their Names: A Retrospective of Black Feminist Literary Criticism,” Signs 32, no. 2 (Winter 2007): 483–507. Preface 9 intergenerational practice. Given the seemingly infinite nodes and entry points of Black feminist thought, it is befitting that this issue coheres because of an unboundedness and porousness among the pieces. The art essays, articles, field reviews, and conversations converse, dance, and harmonize with... (shrink)

Graphical AbstractIn neurons, teneurins and latrophilins form a juxtacrine unit that originated in the earliest metazoans. The ‘teneurin C-terminal associated peptide’ (TCAP) regulates mitochondrial function to coordinate energy usage in surrounding cells. TCAP inhibits stress-related actions of corticotropin-releasing factor (CRF) in the central nervous system and may underlie the etiology of some affective disorders. More details can be found in article number 2000039 by David A. Lovejoy and David W. Hogg. Cover image by Mia Husic.

Mitochondrial replacement techniques have the potential to allow prospective parents who are at risk of passing on debilitating or even life-threatening mitochondrial disorders to have healthy children to whom they are genetically related. Ethical concerns have however been raised about these techniques. This article focuses on one aspect of the ethical debate, the question of whether there is any moral difference between the two types of MRT proposed: Pronuclear Transfer and Maternal Spindle Transfer. It examines how questions of (...) identity impact on the ethical evaluation of each technique and argues that there is an important difference between the two. PNT, it is argued, is a form of therapy based on embryo modification while MST is, instead, an instance of selective reproduction. The article's main ethical conclusion is that, in some circumstances, there is a stronger obligation to use PNT than MST. (shrink)

Mitochondrial replacement techniques are intended to avoid the transmission of mitochondrial diseases from mother to child. MRT represent a potentially powerful new biomedical technology with ethical, policy, economic and social implications. Among other ethical questions raised are concerns about the possible effects on the identity of children born from MRT, their families, and the providers or donors of mitochondria. It has been suggested that MRT can influence identity directly, through altering the genetic makeup and physical characteristics of the (...) child, or indirectly through changing the child's experience of disease, and by generating novel intrafamilial relationships that shape the sense of self. In this article I consider the plausibility and ethical implications of these proposed identity effects, but I focus instead on a third way in which identity may be affected, through the mediating influence of the wider social world on MRT effects on identity. By taking a narrative approach, and examining the nature and availability of identity narratives, I conclude that while neither direct genetic nor indirect experiential effects can be excluded, social responses to MRT are more likely to have a significant and potentially damaging influence on the generation of MRT children's narratives of identity. This conclusion carries some implications for the collective moral responsibility we hold to ensure that MRT, if implemented, are practised in ethically justifiable ways. (shrink)

This article argues that two forms of mitochondrial replacement therapy, maternal spindle transfer and pro-nuclear transfer, are not therapies at all because they do not treat children who are coming into existence. Rather, these technologies merely create healthy children where none was inevitable. Even if creating healthy lives has some value, it is not to be confused with the medical value of a cure or therapy. The article addresses a recent Bioethics article, ‘Mitochondrial Replacement: Ethics and Identity,’ by (...) Wrigley, Wilkinson, and Appleby, who argue that PNT is morally favorable to MST due to the Non-Identity Problem. Wrigley et al. claim that PNT, since it occurs post-conception, preserves the identity of the resulting child, whereas MST, since it occurs pre-conception, is an identity-altering technique. As such, a child born with mitochondrial disease could complain that her parents failed to use PNT, but not MST. The present article argues that the authors are mistaken: both MST and PNT are identity-affecting techniques. But this is of little matter, for we should be cautious in drawing any moral conclusions from the application of the Non-Identity Problem to cases. The article then argues that the authors are mistaken in inferring that PNT is a type of embryonic cure or therapy for children with mitochondrial disease. The article cautions against the mistaken life-saving rhetoric that is common in bioethics discussions of MRTs. (shrink)

Mitochondrial replacement techniques, known in the popular media as 'three-parent' or 'three-person' IVFs, have the potential to enable women with mitochondrial diseases to have children who are genetically related to them but without such diseases. In the debate regarding whether MRTs should be made available, an issue that has garnered considerable attention is whether MRTs affect the characteristics of an existing individual or whether they result in the creation of a new individual, given that MRTs involve the genetic (...) manipulation of the germline. In other words, do MRTs affect the qualitative identity or the numerical identity of the resulting child? For instance, a group of panelists on behalf of the UK Human Fertilisation and Embryology Authority has claimed that MRTs affect only the qualitative identity of the resulting child, while the Working Group of the Nuffield Council on Bioethics has argued that MRTs would create a numerically distinct individual. In this article, I shall argue that MRTs do create a new and numerically distinct individual. Since my explanation is different from the NCOB's explanation, I shall also offer reasons why my explanation is preferable to the NCOB's explanation. (shrink)

Mitochondrial shape change, brought about by molecules that promote either fission or fusion between individual mitochondria, has been documented in several model systems. However, the deeper significance of mitochondrial shape change has only recently begun to emerge: among others, it appears to play a role in the regulation of cell proliferation. Here, I review the emerging interplay between mitochondrial fission‐fusion components with cell cycle regulatory machineries and how that may impact cell differentiation. Regulation of mitochondrial shape (...) may modulate mitochondrial metabolism and/or energetics to promote crosstalk between signaling components and the cell cycle machinery. Focused research in this area will reveal the exact role of mitochondria in development and disease, specifically in stem cell regulation and tumorigenesis. Such research may also reveal whether and how the endosymbiotic event that gave rise to the mitochondrion was crucial for the evolution of cell cycle regulatory mechanisms in eukaryotes that are absent in prokaryotes. (shrink)

The classification of techniques used in mitochondrial donation, including their role as purported germ-line gene therapies, is far from clear. These techniques exhibit characteristics typical of a variety of classifications that have been used in both scientific and bioethics scholarship. This raises two connected questions, which we address in this paper: how should we classify mitochondrial donation techniques?; and what ethical implications surround such a classification? First, we outline how methods of genetic intervention, such as germ-line gene therapy, (...) are typically defined or classified. We then consider whether techniques of mitochondrial donation fit into these, whether they might do so with some refinement of these categories, or whether they require some other approach to classification. To answer the second question, we discuss the relationship between classification and several key ethical issues arising from mitochondrial donation. We conclude that the properties characteristic of mitochondrial inheritance mean that most mitochondrial donation techniques belong to a new sub-class of genetic modification, which we call ‘conditionally inheritable genomic modification’. (shrink)

Currently in the United Kingdom, anyone donating gametes has the status of an open-identity donor. This means that, at the age of 18, persons conceived with gametes donated since April 1, 2005 have a right to access certain pieces of identifying information about their donor. However, in early 2015, the UK Parliament approved new regulations that make mitochondrial donors anonymous. Both mitochondrial donation and gamete donation are similar in the basic sense that they involve the contribution of gamete (...) materials to create future persons. Given this similarity, this paper presumes that both types of donor should be treated the same and made open-identity under the law, unless there is a convincing argument for treating them differently. I argue that none of the existing arguments that have been made so far in favor of mitochondrial donor anonymity are convincing and mitochondrial donors should therefore be treated as open-identity donors under UK law. (shrink)

Heterogeneity in mitochondrial content has been previously suggested as a major contributor to cellular noise, with multiple studies indicating its direct involvement in biomedically important cellular phenomena. A recently published dataset explored the connection between mitochondrial functionality and cell physiology, where a non‐linearity between mitochondrial functionality and cell size was found. Using mathematical models, we suggest that a combination of metabolic scaling and a simple model of cell death may account for these observations. However, our findings also (...) suggest the existence of alternative competing hypotheses, such as a non‐linearity between cell death and cell size. While we find that the proposed non‐linear coupling between mitochondrial functionality and cell size provides a compelling alternative to previous attempts to link mitochondrial heterogeneity and cell physiology, we emphasise the need to account for alternative causal variables, including cell cycle, size, mitochondrial density and death, in future studies of mitochondrial physiology. (shrink)

Inner membranes of mitochondria are extensively folded, forming cristae. The observed overall correlation between efficient eukaryotic ATP generation and the area of internal mitochondrial inner membranes both in unicellular organisms and metazoan tissues seems to explain why they evolved. However, the crucial use of molecular oxygen (O2) as final acceptor of the electron transport chain is still not sufficiently appreciated. O2 was an essential prerequisite for cristae development during early eukaryogenesis and could be the factor allowing cristae retention upon (...) loss of mitochondrial ATP generation. Here I analyze illuminating bacterial and unicellular eukaryotic examples. I also discuss formative influences of intracellular O2 consumption on the evolution of the last eukaryotic common ancestor (LECA). These considerations bring about an explanation for the many genes coming from other organisms than the archaeon and bacterium merging at the start of eukaryogenesis. (shrink)

Mitochondrial replacement technology (MRT) is an emerging and complex bioethical issue. This treatment aims to eliminate maternal inherited mitochondrial DNA (mtDNA) disorders. For Muslims, its introduction affects every aspect of human life, especially the five essential interests of human beings—namely, religion, life, lineage, intellect, and property. Thus, this technology must be assessed using a comprehensive and holistic approach addressing these human essential interests. Consequently, this article analyses and assesses tri-parent baby technology from the perspective of Maqasidic bioethics—that is, (...) Islamic bioethics based on the framework of Maqasid al-Shariah. Using this analysis, this article suggests that tri-parent baby technology should not be permitted for Muslims due to the existence of third-party cell gametes which lead to lineage mixing and due to the uncertain safety of the therapy itself and because the major aim of the technology is to fulfil the affected couples interest to conceive their own genetically healthy child, not to treat and cure mtDNA disorders sufferers. (shrink)

Mitochondrial function is key for maintaining cellular health, while mitochondrial failure is associated with various pathologies, including inherited metabolic disorders and age‐related diseases. In order to maintain mitochondrial quality, several pathways of mitochondrial quality control have evolved. These systems monitor mitochondrial integrity through antioxidants, DNA repair systems, and chaperones and proteases involved in the mitochondrial unfolded protein response. Additional regulation of mitochondrial function involves dynamic exchange of components through mitochondrial fusion and fission. (...) Sustained stress induces a selective autophagy – termed mitophagy – and ultimately leads to apoptosis. Together, these systems form a network that acts on the molecular, organellar, and cellular level. In this review, we highlight how these systems are regulated in an integrated context‐ and time‐dependent network of mitochondrial quality control that is implicated in healthy aging. (shrink)

We review a recent paper in Genome Research by Guantes et al. showing that nuclear gene expression is influenced by the bioenergetic status of the mitochondria. The amount of energy that mitochondria make available for gene expression varies considerably. It depends on: the energetic demands of the tissue; the mitochondrial DNA (mtDNA) mutant load; the number of mitochondria; stressors present in the cell. Hence, when failing mitochondria place the cell in energy crisis there are major effects on gene expression (...) affecting the risk of degenerative diseases, cancer and ageing. In 2015 the UK parliament approved a change in the regulation of IVF techniques, allowing “Mitochondrial replacement therapy” to become a reproductive choice for women at risk of transmitting mitochondrial disease to their children. This is the first time that this technique will be available. Therefore understanding the interaction between mitochondria and the nucleus has never been more important. (shrink)

Mitochondrial replacement therapy (MRT), also called nuclear genome transfer and mitochondrial donation, is a new technique that can be used to prevent the transmission of mitochondrial DNA diseases. Apart from the United Kingdom, the first country to approve MRT in 2015, Australia became the second country with a clear regulatory path for the clinical applications of this technique in 2021. The rapidly evolving clinical landscape of MRT makes the elaboration and evaluation of the responsible use of this (...) technology a pressing matter. As jurisdictions with less strict or non-existent reproductive laws are continuing to use MRT in the clinical context, the need to address the underlying ethical issues surrounding MRT’s clinical translation is fundamental. (shrink)

In February 2015 the UK became the first country to legalise high-profile mitochondrial replacement techniques, which involve the creation of offspring using genetic material from three individuals. The aim of these new cell reconstruction techniques is to prevent the transmission of maternally inherited mitochondrial disorders to biological offspring. During the UK debates, MRTs were often positioned as a straightforward and unique solution for the ‘eradication’ of mitochondrial disorders, enabling hundreds of women to have a healthy, biologically-related child. (...) However, many questions regarding future applications and potential users remain. Drawing on a current qualitative study on reproductive choices in the context of mitochondrial disorders, this article illustrates how the potential limitations of MRTs have been obscured in public debates by contrasting the claims made about the future beneficiaries with insights from families affected by mitochondrial disorders and medical experts. The analysis illuminates the complex choices with which families and individuals affected by mitochondrial disorders are faced, which have thus far remained invisible. An argument is presented for improved information for the public as well as an intensification of critical empirical research around the complex and specific needs of future beneficiaries of new reproductive biotechnologies. (shrink)

Much research has focused on the effects of pathogenic mitochondrial mutations on health. Notwithstanding, the mechanisms regulating the link between these mutations and their effects remain elusive in several cases. Here, we propose that certain mitochondrial mutations may disrupt function of a set of mitochondrial‐transcribed small RNAs, perturbing communication between mitochondria and nucleus, leading to disease. Our hypothesis synthesises two lines of supporting evidence. First, several mitochondrial mutations cannot be directly linked to effects on energy production (...) or protein synthesis. Second, emerging studies have described the existence of small RNAs encoded by the mitochondria and proposed their involvement in RNA interference. We present a roadmap to testing this hypothesis. (shrink)

Mitochondrial bioenergetics plays a key role in multiple basic cellular processes, such as energy production, nucleotide biosynthesis, and iron metabolism. It is an essential system for animals' life and death (apoptosis) and it is required for embryo development. This, in conjunction with its being subjected to adaptive processes in multiple species and its gene products being involved in the formation of reproductive barriers in animals, raises the possibility that mitochondrial bioenergetics could be a candidate genetic mechanism of speciation. (...) Here, we discuss genetic and biochemical evidence for the possible involvement of this unique system, encoded by two genomes (the mitochondrial and nuclear genomes), that differ by an order of magnitude in their mutation rates in processes leading to speciation events. (shrink)