Rohwer & Marris claim that “many conservation biologists” believe that there is a prima facie duty to preserve the genetic integrity of species. (A prima facie duty is a necessary pro tanto moral reason.) They describe three possible arguments for that belief and reject them all. They conclude that the biologists they cite are mistaken, and that there is no such duty: duties to preserve genetic integrity are merely instrumental: we ought act to preserve genetic integrity only because doing (...) so is required by some other duty, such as the duty to preserve taxonomic biodiversity, or the duty to preserve the reproductive fitness of existing species. In permitting for instance the introgression of cattle genes into the genome of Bison bison we therefore do not necessarily fail in any respect ethically. I criticize the paper on three fronts. (shrink)

Who gets to practice and participate in science? Research teams in Puerto Rico and New Zealand have each sequenced the genomes of parrot populations native to these locales: the iguaca and kākāpō, respectively. In both cases, crowdfunding and social media were instrumental in garnering public interest and funding. These forms of Internet-mediated participation impacted how conservation science was practiced in these cases and shaped emergent social roles and relations. As citizens “follow,” fund, and “like” the labor of conservation, (...) they create new relational possibilities for and with science. For example, the researchers became newly engaged and engaging by narrating and displaying the parrots via an Internet-inflected aesthetic. The visibility of online modalities shifted accountabilities as researchers considered whom this crowdfunded work answered to and how to communicate their progress and results. The affordances of the Internet allowed researchers from the peripheries of the scientific establishment to produce genomic knowledge for globally dispersed audiences. The convergence of genomic and Internet technology here shaped scientific practice by facilitating new modes of participation—for laypeople in science but also for scientists in society. (shrink)

Somatic diversification of antigen receptor genes depends on the activity of enzymes whose homologs participate in a mutagenic DNA repair in unicellular species. Indeed, by engaging error-prone polymerases, gap filling molecules and altered mismatch repair pathways, lymphocytes utilize conserved components of genomic stress response systems, which can already be found in bacteria and archaea. These ancient systems of mutagenesis and repair act to increase phenotypic diversity of microbial cell populations and operate to enhance their ability to produce fit variants (...) during stress. Coopted by lymphocytes, the ancient mutagenic processing systems retained their diversification functions instilling the adaptive immune cells with enhanced evolvability and defensive capacity to resist infection and damage. As reviewed here, the ubiquity and conserved character of specialized variation-generating mechanisms from bacteria to lymphocytes highlight the importance of these mechanisms for evolution of life in general. (shrink)

The horse was essential to past human societies but became a recreational animal during the twentieth century as the world became increasingly mechanized. As the author reviews here, recent studies of ancient genomes have revisited the understanding of horse domestication, from the very early stages to the most modern developments. They have uncovered several extinct lineages roaming the far ends of Eurasia some 4000 years ago. They have shown that the domestic horse has been significantly reshaped during the last millennium (...) and experienced a sharp decline in genetic diversity within the last two centuries. At a time when no truly wild horses exist any longer, this calls for enhanced conservation in all endangered populations. These include the Przewalski's horse native to Mongolia, and the many local breeds side‐lined by the modern agenda, but yet representing the living heritage of over five millennia of horse breeding. (shrink)

The genomes of vertebrates, flies, and nematodes contain highly conserved noncoding elements (CNEs). CNEs cluster around genes that regulate development, and where tested, they can act as transcriptional enhancers. Within an animal group CNEs are the most conserved sequences but between groups they are normally diverged beyond recognition. Alternative CNEs are, however, associated with an overlapping set of genes that control development in all animals. Here, we discuss the evidence that CNEs are part of the core gene regulatory networks (GRNs) (...) that specify alternative animal body plans. The major animal groups arose >550 million years ago. We propose that the cis‐regulatory inputs identified by CNEs arose during the “re‐wiring” of regulatory interactions that occurred during early animal evolution. Consequently, different animal groups, with different core GRNs, contain alternative sets of CNEs. Due to the subsequent stability of animal body plans, these core regulatory sequences have been evolving in parallel under strong purifying selection in different animal groups. (shrink)

Nicotinic acetylcholine receptors (nAChRs) are ligand‐gated ion channels that bring about a diversity of fast synaptic actions. Analysis of the Caenorhabditis elegans genome has revealed one of the most‐extensive and diverse nAChR gene families known, consisting of at least 27 subunits. Striking variation with possible functional implications has been observed in normally conserved motifs at the acetylcholine‐binding site and in the channel‐lining region. Some nAChR subunits are particular to neurons whilst others are present in both neurons and muscles. The localization (...) of subunits in non‐synaptic regions suggests novel roles for nAChRs. Genetic and heterologous expression studies have identified a subset of nAChR subunits that are important drug targets while the study of mutants has identified genes functionally‐linked to nAChRs. Future studies using C. elegans offer the prospect of increasing our understanding of the functional diversity of a complex nAChR gene family as well as addressing the role of nAChRs and associated proteins in human disorders. BioEssays 26:39–49, 2004.© 2003 Wiley Periodicals, Inc. (shrink)

Community engagement (CE) contributes to successful research. There is, however, a lack of literature on the effectiveness of different models of CE and, specifically, on CE strategies for the conduct of genomic research in sub-Saharan Africa. There is also a need for models of CE that transcend the recruitment stage of engaging prospective individuals and communities and embed CE throughout the research process and after the research has concluded. The qualitative study reported here was designed to address these knowledge (...) gaps and comprised of 36 key informant semi-structured interviews and fifteen focus groups with 50 participants. We interviewed selected stakeholders in genomic research in Nigeria: biomedical researchers, community rulers, opinion leaders, community health workers, and prospective research participants. We explored these stakeholders’ views on their understanding of community engagement, their expectations, experiences, and their opinions on acceptable processes of community consultation in genomic research. The methodological design, adapted from grounded theory, used the constant comparative method of data analysis; while normative conclusions were made using the symbiotic empirical ethics approach. Data analysis revealed five main themes important for successfully engaging communities in genomic research: effective communication, diversity of community gatekeeping, trust, cultural integration of research, and conservation of the research setting. From these themes, we have developed a four-stage model of community engagement that covers all stages of the research process; namely, the Community Approach, Intermediate phase, Collaboration and Post-research Cordiality model (CICP). This model could be used to improve the integration of CE in genomic research among local communities. (shrink)

Community engagement (CE) contributes to successful research. There is, however, a lack of literature on the effectiveness of different models of CE and, specifically, on CE strategies for the conduct of genomic research in sub-Saharan Africa. There is also a need for models of CE that transcend the recruitment stage of engaging prospective individuals and communities and embed CE throughout the research process and after the research has concluded. The qualitative study reported here was designed to address these knowledge (...) gaps and comprised of 36 key informant semi-structured interviews and fifteen focus groups with 50 participants. We interviewed selected stakeholders in genomic research in Nigeria: biomedical researchers, community rulers, opinion leaders, community health workers, and prospective research participants. We explored these stakeholders’ views on their understanding of community engagement, their expectations, experiences, and their opinions on acceptable processes of community consultation in genomic research. The methodological design, adapted from grounded theory, used the constant comparative method of data analysis; while normative conclusions were made using the symbiotic empirical ethics approach. Data analysis revealed five main themes important for successfully engaging communities in genomic research: effective communication, diversity of community gatekeeping, trust, cultural integration of research, and conservation of the research setting. From these themes, we have developed a four-stage model of community engagement that covers all stages of the research process; namely, the Community Approach, Intermediate phase, Collaboration and Post-research Cordiality model (CICP). This model could be used to improve the integration of CE in genomic research among local communities. (shrink)

Community engagement (CE) contributes to successful research. There is, however, a lack of literature on the effectiveness of different models of CE and, specifically, on CE strategies for the conduct of genomic research in sub-Saharan Africa. There is also a need for models of CE that transcend the recruitment stage of engaging prospective individuals and communities and embed CE throughout the research process and after the research has concluded. The qualitative study reported here was designed to address these knowledge (...) gaps and comprised of 36 key informant semi-structured interviews and fifteen focus groups with 50 participants. We interviewed selected stakeholders in genomic research in Nigeria: biomedical researchers, community rulers, opinion leaders, community health workers, and prospective research participants. We explored these stakeholders’ views on their understanding of community engagement, their expectations, experiences, and their opinions on acceptable processes of community consultation in genomic research. The methodological design, adapted from grounded theory, used the constant comparative method of data analysis; while normative conclusions were made using the symbiotic empirical ethics approach. Data analysis revealed five main themes important for successfully engaging communities in genomic research: effective communication, diversity of community gatekeeping, trust, cultural integration of research, and conservation of the research setting. From these themes, we have developed a four-stage model of community engagement that covers all stages of the research process; namely, the Community Approach, Intermediate phase, Collaboration and Post-research Cordiality model (CICP). This model could be used to improve the integration of CE in genomic research among local communities. (shrink)

Community engagement (CE) contributes to successful research. There is, however, a lack of literature on the effectiveness of different models of CE and, specifically, on CE strategies for the conduct of genomic research in sub-Saharan Africa. There is also a need for models of CE that transcend the recruitment stage of engaging prospective individuals and communities and embed CE throughout the research process and after the research has concluded. The qualitative study reported here was designed to address these knowledge (...) gaps and comprised of 36 key informant semi-structured interviews and fifteen focus groups with 50 participants. We interviewed selected stakeholders in genomic research in Nigeria: biomedical researchers, community rulers, opinion leaders, community health workers, and prospective research participants. We explored these stakeholders’ views on their understanding of community engagement, their expectations, experiences, and their opinions on acceptable processes of community consultation in genomic research. The methodological design, adapted from grounded theory, used the constant comparative method of data analysis; while normative conclusions were made using the symbiotic empirical ethics approach. Data analysis revealed five main themes important for successfully engaging communities in genomic research: effective communication, diversity of community gatekeeping, trust, cultural integration of research, and conservation of the research setting. From these themes, we have developed a four-stage model of community engagement that covers all stages of the research process; namely, the Community Approach, Intermediate phase, Collaboration and Post-research Cordiality model (CICP). This model could be used to improve the integration of CE in genomic research among local communities. (shrink)

The major transcript variants of human protein‐coding genes are annotated to a certain degree of accuracy combining manual curation, transcript data, and proteomics evidence. However, there is considerable disagreement on the annotation of about 2000 genes—they can be protein‐coding, noncoding, or pseudogenes—and on the annotation of most of the predicted alternative transcripts. Pure transcriptome mapping approaches seem to be limited in discriminating functional expression from noise. These limitations have partially been overcome by dedicated algorithms to detect alternative spliced micro‐exons and (...) wobble splice variants. Recently, knowledge about splice mechanism and protein structure are incorporated into an algorithm to predict neighboring homologous exons, often spliced in a mutually exclusive manner. Predicted exons are evaluated by transcript data, structural compatibility, and evolutionary conservation, revealing hundreds of novel coding exons and splice mechanism re‐assignments. The emerging human pan‐genome is necessitating distinctive annotations incorporating differences between individuals and between populations. (shrink)

Frequent evolutionary birth and death events have created a large quantity of biologically important, lineage‐specific DNA within mammalian genomes. The birth and death of DNA sequences is so frequent that the total number of these insertions and deletions in the human population remains unknown, although there are differences between these groups, e.g. transposable elements contribute predominantly to sequence insertion. Functional turnover – where the activity of a locus is specific to one lineage, but the underlying DNA remains conserved – can (...) also drive birth and death. However, this does not appear to be a major driver of divergent transcriptional regulation. Both sequence and functional turnover have contributed to the birth and death of thousands of functional promoters in the human and mouse genomes. These findings reveal the pervasive nature of evolutionary birth and death and suggest that lineage‐specific regions may play an important but previously underappreciated role in human biology and disease. (shrink)

This paper addresses the cultural impact of genomics and the Human Genome Project on human self-understanding. Notably, it addresses the claim made by Francis Collins that the genome is the language of God and the claim made by Max Delbrück that Aristotle must be credited with having predicted DNA as the soul that organises bio-matter. From a continental philosophical perspective I will argue that human existence results from a dialectical interaction between two types of texts: the language of molecular biology (...) and the language of civilisation; the language of the genome and the language of our socio-cultural, symbolic ambiance. Whereas the former ultimately builds on the alphabets of genes and nucleotides, the latter is informed by primordial texts such as the Bible and the Quran. In applied bioethics deliberations on genomics, science is easily framed as liberating and progressive, religious world-views as conservative an... (shrink)

Despite the enormous diversity in plant form, structure and growth environment across the seed‐bearing plants (angiosperms and gymnosperms), the chloroplast genome has, with few exceptions, remained remarkably conserved. This conservation suggests the existence of universal evolutionary selection pressures associated with photosynthesis—the primary function of chloroplasts. The stark exceptions to this conservation occur in parasitic angiosperms, which have escaped the dominant model by evolving the capacity to obtain some or all of their carbon (and nutrients) from their plant hosts. (...) The consequence of this evolution to parasitism is a relaxation of the evolutionary constraints associated with the need to maintain photosynthetic function, the very function that drove early stages of the ancient symbiotic relationship that produced the contemporary chloroplast. Extreme examples of reductionism among parasitic angiosperms reveals major alterations in chloroplast function with the loss of photosynthetic capacity and, with that, massive alterations in chloroplast genome content. This review highlights emerging patterns in reported gene loss and gene retention in the chloroplast genomes of parasitic plants. Some gene losses appear to occur in the early stages of parasitic evolution, even before the loss of photosynthetic capacity, like the chlororespiratory (ndh) genes. This contrasts with unexpected gene retentions, like that of the rbcL gene responsible for photosynthetic carbon dioxide fixation, and belies current understanding of gene function. The review relates gene retention to current knowledge of protein function and gene processing that has implications to broader aspects of genome conservation in organelles. BioEssays 26:235–247, 2004. Wiley Periodicals, Inc. (shrink)

One interesting feature of de‐extinction—particularly with respect to long‐extinct species such as the passenger pigeon, thylacine, and mammoth—is that it does not fit neatly into the primary rationales for adopting novel ecosystem‐management and species‐conservation technologies and strategies: efficiency and necessity. The efficiency rationale is that the new technology or strategy enables conservation biologists to do what they already do more effectively. Why should researchers embrace novel information technologies? Because they allow scientists to better track, monitor, map, aggregate, and (...) analyze species behaviors, biological systems, and human‐environment interactions. This enables better decision‐making about how to protect species, which areas to conserve, and how to reduce anthropogenic impacts on ecological systems. Many projects in conservation genomics are justified in this way. But de‐extinction is not a more efficient or necessary means to some conservation aim that is already recognized as acceptable or important. In fact, because it is focused on reconstituting approximations of nonexistent species, rather than maintaining extant ones, the social and ethical assessment of de‐extinction is not limited to asking whether it is a good means. We can ask as well whether de‐extinction is a worthwhile “conservation” goal in the first place. (shrink)

The discovery of CRISPR/cas9 has opened new avenues in gene editing. This system, usually considered as molecular scissors, permits the cutting of the DNA at a targeted site allowing the introduction of new genes or the removal or the modification of existing ones. The genome-editing, involving gene drive or not, is then considered with a strong interest in a variety of fields ranging from agriculture to public health and conservation biology. Given its controversial aspects, it is then no surprise (...) that actors in biodiversity conservation do express conflicting views on this emerging and disruptive technology. The positions are ranging from a request for a moratorium to the will to test and deploy it in strategies aiming at eradicating invasive species of mammals on islands. Reviewing some of its recent developments brings light on the conflicts of interest, the financial support, and lobbying currently occurring in this growing field of biotechnology. While an optimistic view on the use of gene drive for ecosystem conservation was first promoted by several molecular biologists, the risks and uncertainties associated have now led to some reservations. Overall, the eventual use of this novel approach for conservation raises concerns related to the engagement of the public, the communication between scientists, and the public and the risk of a manufactured consent. There are also a series of essential ethical and philosophical questions on the relations we have with Nature that needs to be answered. (shrink)

Barbieri introduced and developed the concept of organic codes. The most basic of them is the genetic code, a set of correspondence rules between otherwise unrelated sequences: strings of nucleotides on the one hand, polypeptidic chains on the other hand. Barbieri noticed that it implies ‘coding by convention’ as arbitrary as the semantic relations a language establishes between words and outer objects. Moreover, the major transitions in life evolution originated in new organic codes similarly involving conventional rules. Independently, dealing with (...) heredity as communication over time and relying on information theory, we asserted that the conservation of genomes over the ages demands that error-correcting codes make them resilient to casual errors. Moreover, the better conservation of very old parts of the genome demands that they result from combining successively established nested codes such that the older an information, the more numerous component codes protect it. Barbieri’s concept of organic code and that of genomic error-correcting code may seem unrelated. We show however that organic codes actually entail error-correcting properties. Error-correcting, in general, results from constraints being imposed on a set of sequences. Mathematical equalities are conveniently used in communication engineering for expressing constraints but error correction only needs that constraints exist. Biological sequences are similarly endowed with error-correcting ability by physical-chemical or linguistic constraints, thus defining ‘soft codes’. These constraints are moreover presumably efficient for correcting errors. Insofar as biological sequences are subjected to constraints, organic codes necessarily involve soft codes, and their successive onset results in the nested structure we hypothesized. Organic codes are generated and maintained by means of molecular ‘semantic feedback loops’. Each of these loops involves genes which code for proteins, the enzymatic action of which controls a function needed for the protein assembly. Taken together, thus, they control the assembly of their own structure as instructed by the genome and, once closed, these loops ensure their own conservation. However, the semantic feedback loops do not prevent the genome lengthening. It increases both the redundancy of the genome and the information quantity it bears, thus improving the genome reliability and the specificity of the enzymes, which enables further evolution. (shrink)

Identifying genomic homology within and between genomes is essential when studying genome evolution. In the past years, different computational techniques have been developed to detect homology even when the actual similarity between homologous segments is low. Depending on the strategy used, these methods search for pairs of chromosomal segments between which either both gene content and order are conserved or gene content only. However, due to fact that, after their divergence, homologous segments can lose a different set of genes, (...) these methods still often fail to detect genomic homology. Recently, more advanced approaches have been developed that can combine gene order and content information of multiple genomic segments. BioEssays 26:1225–1235, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

Sponges are important but often‐neglected organisms. The absence of classical animal traits (nerves, digestive tract, and muscles) makes sponges challenging for non‐specialists to work with and has delayed getting high quality genomic data compared to other invertebrates. Yet analyses of sponge genomes and transcriptomes currently available have radically changed our understanding of animal evolution. Sponges are of prime evolutionary importance as one of the best candidates to form the sister group of all other animals, and genomic data are (...) essential to understand the mechanisms that control animal evolution and diversity. Here we review the most significant outcomes of current genomic and transcriptomic analyses of sponges, and discuss limitations and future directions of sponge transcriptomic and genomic studies. (shrink)

Yasha Rohwer and Emma Marris argue there is no prima facie duty to preserve genetic integrity; they contend, rather, that preserving the integrity of specific genomes is only a mean...

The chromodomain is a highly conserved sequence motif that has been identified in a variety of animal and plant species. In mammals, chromodomain proteins appear to be either structural components of large macromolecular chromatin complexes or proteins involved in remodelling chromatin structure. Recent work has suggested that apart from a role in regulating gene activity, chromodomain proteins may also play roles in genome organisation. This article reviews progress made in characterising mammalian chromodomain proteins and emphasises their emerging role in the (...) regulation of gene expression and genome organisation. BioEssays 22:124–137, 2000. ©2000 John Wiley & Sons, Inc. (shrink)

Despite decades of research, morphogenesis along the various body axes remains one of the major mysteries in developmental biology. A milestone in the field was the realisation that a set of closely related regulators, called Hox genes, specifies the identity of body segments along the anterior–posterior (AP) axis in most animals. Hox genes have been highly conserved throughout metazoan evolution and code for homeodomain‐containing transcription factors. Thus, they exert their function mainly through activation or repression of downstream genes. However, while (...) much is known about Hox gene structure and molecular function, only a few target genes have been identified and studied in detail. Our knowledge of Hox downstream genes is therefore far from complete and consequently Hox‐controlled morphogenesis is still poorly understood. Genome‐wide approaches have facilitated the identification of large numbers of Hox downstream genes both in Drosophila and vertebrates, and represent a crucial step towards a comprehensive understanding of how Hox proteins drive morphological diversification. In this review, we focus on the role of Hox genes in shaping segmental morphologies along the AP axis in Drosophila, discuss some of the conclusions drawn from analyses of large target gene sets and highlight methods that could be used to gain a more thorough understanding of Hox molecular function. In addition, the mechanisms of Hox target gene regulation are considered with special emphasis on recent findings and their implications for Hox protein specificity in the context of the whole organism. BioEssays 30:965–979, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

The chromodomain is a highly conserved sequence motif that has been identified in a variety of animal and plant species. In mammals, chromodomain proteins appear to be either structural components of large macromolecular chromatin complexes or proteins involved in remodelling chromatin structure. Recent work has suggested that apart from a role in regulating gene activity, chromodomain proteins may also play roles in genome organisation. This article reviews progress made in characterising mammalian chromodomain proteins and emphasises their emerging role in the (...) regulation of gene expression and genome organisation. BioEssays 22:124–137, 2000. ©2000 John Wiley & Sons, Inc. (shrink)

New genes have frequently formed and spread to fixation in a wide variety of organisms, constituting abundant sets of lineage‐specific genes. It was recently reported that an excess of primate‐specific and human‐specific genes were upregulated in the brains of fetuses and infants, and especially in the prefrontal cortex, which is involved in cognition. These findings reveal the prevalent addition of new genetic components to the transcriptome of the human brain. More generally, these findings suggest that genomes are continually evolving in (...) both sequence and content, eroding the conservation endowed by common ancestry. Despite increasing recognition of the importance of new genes, we highlight here that these genes are still seriously under‐characterized in functional studies and that new gene annotation is inconsistent in current practice. We propose an integrative approach to annotate new genes, taking advantage of functional and evolutionary genomic methods. We finally discuss how the refinement of new gene annotation will be important for the detection of evolutionary forces governing new gene origination. (shrink)

One of the distinctive features of the primate genome is the Alu element, a repetitive short interspersed element, over a million highly similar copies of which account for >10% of the genome. A direct consequence of this feature is that primates' transcriptome is highly enriched in long stable dsRNA structures, the preferred target of adenosine deaminases acting on RNAs (ADARs), which are the enzymes catalyzing A‐to‐I RNA editing. Indeed, A‐to‐I editing by ADARs is extremely abundant in primates: over a hundred (...) million editing sites exist in their genomes. However, there are few essential editing sites conserved across mammals that have maintained their editing level despite the radical change in ADAR target landscape. Here, we review and discuss the cost of having an unusual amount of dsRNA and editing in the transcriptome, as well as the opportunities it presents, which might have contributed to the accelerated evolution of the primates. (shrink)

Homology searches between DNA sequences of evolutionary distant species (phylogenetic footprinting) offer a fast detection method for regulatory sequences. Because of the small size of their genomes, tetraodontid species such as the Japanese pufferfish and green spotted pufferfish have become attractive models for comparative genomics. A disadvantage of the tetraodontid species is, however, that they cannot be bred and manipulated routinely under laboratory conditions, so these species are less attractive for developmental and genetic analysis. In contrast, an increasing arsenal of (...) transgene techniques with the developmental model species zebrafish and medaka are being used for functional analysis of cis regulatory sequences. The main disadvantage is the much larger genome. While comparison between many loci proved the suitability of phylogenetic footprinting using fish and mammalian sequences, fast rate of change in enhancer structure and gene duplication within teleosts may obscure detection of homologies. Here we discuss the contribution and potentials provided by different teleost models for the detection and functional analysis of conserved cis‐regulatory elements. BioEssays 24:564–572, 2002. © 2002 Wiley Periodicals, Inc. (shrink)

Rattus norvegicus is an important experimental organism and interesting to evolutionary biologists. The recently published draft rat genome sequence1 provides us with insights into both the rat's evolution and its physiology. We learn more about genome evolution and, in particular, the adaptive significance of gene family expansions and the evolution of rodent genomes, which appears to have decelerated since the divergence of mouse and rat. An important observation is that some regions of genomes, many in noncoding regions, show very high (...) sequence conservation, while others show unexpectedly fast evolution. Both of these may be pointers to functional significance. BioEssays 26:1039–1042, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

Transcription is a potential threat to genome integrity, and transcription‐associated DNA damage must be repaired for proper messenger RNA (mRNA) synthesis and for cells to transmit their genome intact into progeny. For a wide range of structurally diverse DNA lesions, cells employ the highly conserved nucleotide excision repair (NER) pathway to restore their genome back to its native form. Recent evidence suggests that NER factors function, in addition to the canonical DNA repair mechanism, in processes that facilitate mRNA synthesis or (...) shape the 3D chromatin architecture. Here, these findings are critically discussed and a working model that explains the puzzling clinical heterogeneity of NER syndromes highlighting the relevance of physiological, transcription‐associated DNA damage to mammalian development and disease is proposed. (shrink)

Integrative mobile genetic elements (MGEs), such as transposons and insertion sequences, propagate within bacterial genomes, but persistence times in individual lineages are short. For long‐term survival, MGEs must continuously invade new hosts by horizontal transfer. Theoretically, MGEs that persist for millions of years in single lineages, and are thus subject to vertical inheritance, should not exist. Here we draw attention to an exception – a class of MGE termed REPIN. REPINs are non‐autonomous MGEs whose duplication depends on non‐jumping RAYT transposases. (...) Comparisons of REPINs and typical MGEs show that replication rates of REPINs are orders of magnitude lower, REPIN population size fluctuations correlate with changes in available genome space, REPIN conservation depends on RAYT function, and REPIN diversity accumulates within host lineages. These data lead to the hypothesis that REPINs form enduring, beneficial associations with eubacterial chromosomes. Given replicative nesting, our hypothesis predicts conflicts arising from the diverging effects of selection acting simultaneously on REPINs and host genomes. Evidence in support comes from patterns of REPIN abundance and diversity in two distantly related bacterial species. Together this bolsters the conclusion that REPINs are the genetic counterpart of mutualistic endosymbiotic bacteria. (shrink)

Methylation of cytosine DNA residues is a well‐studied epigenetic modification with important roles in formation of heterochromatic regions of the genome, and also in tissue‐specific repression of transcription. However, we recently found that the ciliate Oxytricha uses methylcytosine in a novel DNA elimination pathway important for programmed genome restructuring. Remarkably, mounting evidence suggests that methylcytosine can play a dual role in ciliates, repressing gene expression during some life‐stages and directing DNA elimination in others. In this essay, I describe these recent (...) advances in the DNA methylation field and discuss whether this unexpected novel role for methylcytosine in DNA elimination might be more widely conserved in eukaryotic biology, particularly in apoptotic pathways. (shrink)

Despite the remarkable achievements of novel targeted anti‐cancer drugs, most therapies only produce remission for a limited time, resistance to treatment, and relapse, often being the ultimate outcome. Drug resistance is due to highly efficient adaptive strategies utilized by cancer cells. Exogenous and endogenous stress stimuli are known to induce first‐line responses, capable of re‐establishing cellular homeostasis and determining cell fate decisions. Cancer cells may also mount second‐line adaptive strategies, such as the mutator response. Hypermutable subpopulations of cells may expand (...) under severe selective stress, thereby accelerating the emergence of adapted clones. As with first‐line protective responses, these strategies appear highly conserved, and are found in yeasts and bacteria. We hypothesize that evolutionarily conserved programs rheostatically regulate mutability in fluctuating environments, and contribute to drug resistance in cancer cells. Elucidating the conserved genetic and molecular mechanisms may present novel opportunities to increase the effectiveness of cancer therapies. (shrink)

Homology has been one of, if not the most, fecund concepts which has been used towards the understanding of the genomes of the model organisms. The evidence for this claim can be supported best with an examination of current research in comparative genomics. In comparative genomics, the information of genes or segments of the genome, and their location and sequence, are used to search for genes similar to them, known as 'homologues'. Homologues can be either within that same organism (paralogues), (...) or among different species (orthologues). The importance in finding homologous genes within organisms or across species is that these similarities indicate the possibility of ascribing functions, mechanisms or structures which are required by a variety of species which present the same homology. The interest in structures and functions of genes and proteins common to multiple species is one of the main foci of comparative genomics. Because of this, research into the conservation of genes has been the basis of comparison with regards to homologous genes among diverse organisms. Different causal processes are involved in genetic pathways and mechanisms. Explanations of these depend upon which pathway, structure or mechanism is picked out. Each process has a different causal network to which different explanations refer. What comparative genomics explains are the different causal mechanisms which occur in processes such as differentiation, protein synthesis, and gene regulation. How these processes interact within the organism can only be understood when compared with organisms which possess homologous genes, gene sequences, similar developmental mechanisms, or those whose mechanisms for gene regulation are similar. Explanations which result from comparative genomics contribute to a more comprehensive understanding of both the complex structures and the diverse functions within the genomes of different organisms. There are two related problems which have plagued attempts to define the concept of homology. The first problem arises in clarifying what kind of similarity is involved in a homological comparison. A second problem occurs if more than one concept of homology is needed to pick out the kinds of similarity in different contexts of homological comparison. Homology is usually understood as picking out what counts as 'the same' between two or more organisms. Many of the attempts which have been made to define the concept of homology focus on which criteria are used to restrict the kinds of similarity which exist between two or more organisms or parts being compared. These are criteria which can be used reliably to infer shared ancestry. However, there have been many different attempts to define similarity which have produced a profusion of homology concepts. This profusion has led both to the conflation of what counts as 'the same' in different contexts and has also muddled the relations of comparison which various concepts use to identify homologues. (shrink)

Decades of globally coordinated work in conservation have failed to slow the loss of biodiversity. To do better—even if that means nothing more than failing less spectacularly—bolder thinking is necessary. One of the first possible conservation applications of synthetic biology to be debated is the use of genetic tools to resurrect once‐extinct species. Since the currency of conservation is biodiversity and the discipline of conservation biology was formed around the prevention of species extinctions, the prospect of (...) reversing extinctions might have been expected to generate unreserved enthusiasm. But it was not universal acclaim that greeted the coming‐out party for “de‐extinction” that was the TEDx conference and accompanying National Geographic feature in 2013. Why the concern, the skepticism, even the hostility among many conservationists about the idea of restoring lost species? And how does this professional concern relate to public perception and support for conservation? This essay explores the barriers to the acceptance of risky new genomic‐based conservation tools by considering five key areas and associated questions that could be addressed in relation to any new conservation tool. I illustrate these using the specific example of de‐extinction, and in doing so, I consider whether de‐extinction would necessarily be the best first point of engagement between conservation biology and synthetic biology. (shrink)

DREAM complexes are transcriptional regulators that control the expression of hundreds to thousands of target genes involved in the cell cycle, quiescence, differentiation, and apoptosis. These complexes contain many subunits that can vary according to the considered target genes. Depending on their composition and the nature of the partners they recruit, DREAM complexes control gene expression through diverse mechanisms, including chromatin remodeling, transcription cofactor and factor recruitment at various genomic binding sites. This complexity is particularly high in mammals. Since (...) the discovery of the first dREAM complex (drosophila Rb, E2F, and Myb) in Drosophila melanogaster, model organisms such as Caenorhabditis elegans, and plants allowed a deeper understanding of the processes regulated by DREAM‐like complexes. Here, we review the conservation of these complexes. We discuss the contribution of model organisms to the study of DREAM‐mediated transcriptional regulatory mechanisms and their relevance in characterizing novel activities of DREAM complexes. (shrink)

Nonsense‐mediated RNA decay (NMD) is an evolutionary conserved system of RNA surveillance that detects and degrades RNA transcripts containing nonsense mutations. Given that these mutations arise at a relatively low frequency, are there any as yet unknown substrates of NMD in a wild‐type cell? With this question in mind, Mendell et al.1 have used a microarray assay to identify those human genes under NMD regulation. Their results show that, in human cells, NMD regulates hundreds of physiologic transcripts and not just (...) those containing nonsense mutations. Among the NMD targets are a number of non‐functional RNAs expressed from vestigial sequences derived from retroviral and transposable elements. These findings support the notion that NMD is a high profile post‐transcriptional mechanism micromanaging the activity of multiple gene batteries and suppressing the expression of genetic remnants. BioEssays 27:463–466, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Kennedy Institute of Ethics Journal 14.1 (2004) 47-54 [Access article in PDF] Ethical Guidelines for Human Embryonic Stem Cell Research*(A Recommended Manuscript) Adopted on 16 October 2001Revised on 20 August 2002 Ethics Committee of the Chinese National Human Genome Center at Shanghai, Shanghai 201203 Human embryonic stem cell (ES) research is a great project in the frontier of biomedical science for the twenty-first century. Be- cause the research involves (...) the use of human embryos, it triggers serious debate on ethical issues. Opponents consider the embryo to be an early form of human life that should be respected and not destroyed. However, the majority of scientists support embryonic stem cell research, believing that it offers good prospects for the treatment of diseases that have remained incurable until now and so will benefit humankind. The Ethics Committee of the Department of Ethical, Legal, and Social Implications of the Chinese National Human Genome Center at Shanghai seriously discussed the ethical debate initiated by embryonic stem cell research. We concluded that we should support the scientists of our country in actively carrying out human embryonic stem cell research for the noble cause of "medicine being a beneficent art." For the healthy and orderly development of human embryonic stem cell research in our country, we put forward the following recommended Ethical Guidelines for Human Embryonic Stem Cell Research as a reference for leaders, administrative departments, and related scientists. Preface Article 1. Human embryonic stem cells are the primitive cells that play the main role in the growth and development of a human body. These [End Page 47] primitive cells have the potential for infinite proliferation, self-renewal, and multi-directional differentiation. If scientists can discover the mechanism of differentiation of human embryonic stem cells, it will be possible to induce differentiation of human embryonic stem cells to form various types of human cells for clinical cell therapy. If human embryonic stem cell research can be integrated with modern biomedical engineering techniques, it also will be possible to make repair and replacement of human tissues and organs a reality. Article 2. There are two ways to classify human embryonic stem cells. One way is to classify them according to their potential for differentiation. There could be three kinds of stem cells: totipotent stem cells, pluripotent stem cells, and unipotent stem cells.A totipotent stem cell has the potential to develop into a whole individual. It can differentiate into the more than 200 cell types in the whole body, construct any tissue or organ of the body, and finally develop into a whole individual. The fertilized egg and the cleavage cells at the very early stage of embryonic development are totipotent stem cells.A pluripotent stem cell has the potential to differentiate into many cell types derived from the three embryonic layers. However, it has lost the capacity to develop into a complete organism.A unipotent stem cell is derived from the further differentiation of the pluripotent stem cell. It can differentiate only into one cell type such as a hematopoietic stem cell, neural stem cell, and others.The other way is to classify human stem cells according to their source. There could be two kinds of human stem cells: embryonic stem cells and tissue stem cells (also called adult stem cells). The former involves experimentation with embryos, which has serious ethical implications. Ethical issues associated with the latter are mainly expressed in the various opinions regarding the allocation of health resources. Article 3. Human embryonic stem cells are the group of cells called the blastocyst inner cell mass during the early stage of embryonic development. They are the main source of totipotent stem cells, and hence the focal and hot point in stem cell research. Studies on the clinical application of embryonic stem cells probably will involve use of the somatic cell nucleus transfer (SCNT) technique, which destroys the early human embryo. At present, the ethical and moral debate is very serious in human embryonic stem cell research regarding whether the research will develop... (shrink)

All the conserved detailed results of evolution stored in DNA must be read, transcribed, and translated via an RNAmediated process. This is required for the development and growth of each individual cell. Thus, all known living organisms fundamentally depend on these RNA-mediated processes. In most cases, they are interconnected with other RNAs and their associated protein complexes and function in a strictly coordinated hierarchy of temporal and spatial steps (i.e., an RNA network). Clearly, all cellular life as we know it (...) could not function without these key agents of DNA replication, namely rRNA, tRNA, and mRNA. Thus, any definition of life that lacks RNA functions and their networks misses an essential requirement for RNA agents that inherently regulate and coordinate (communicate to) cells, tissues, organs, and organisms. The precellular evolution of RNAs occurred at the core of the emergence of cellular life and the question remained of how both precellular and cellular levels are interconnected historically and functionally. RNA-networks andRNA-communication can interconnect these levels.With the reemergence of virology in evolution, it became clear that communicating viruses and subviral infectious genetic parasites are bridging these two levels by invading, integrating, coadapting, exapting, and recombining constituent parts in host genomes for cellular requirements in gene regulation and coordination aims. Therefore, a 21st century understanding of life is of an inherently social process based on communicating RNA networks, in which viruses and cells continuously interact. (shrink)

The exocyst is a conserved octameric complex that physically tethers a vesicle to the plasma membrane, prior to membrane fusion. It is important not only for secretion and membrane delivery but also, in mammalian cells, for cytokinesis, ciliogenesis, autophagy, tumorigenesis, and host defense. The combination of genome editing and advanced light microscopy of exocyst subunits in living cells has recently shown the complex to be much more dynamic than previously appreciated, and exposed how little we still know about its function (...) and regulation. (shrink)

Many conserved eukaryotic traits, including apoptosis, two sexes, speciation and ageing, can be causally linked to a bioenergetic requirement for mitochondrial genes. Mitochondrial genes encode proteins involved in cell respiration, which interact closely with proteins encoded by nuclear genes. Functional respiration requires the coadaptation of mitochondrial and nuclear genes, despite divergent tempi and modes of evolution. Free‐radical signals emerge directly from the biophysics of mosaic respiratory chains encoded by two genomes prone to mismatch, with apoptosis being the default penalty for (...) compromised respiration. Selection for genomic matching is facilitated by two sexes, and optimizes fitness, adaptability and fertility in youth. Mismatches cause infertility, low fitness, hybrid breakdown, and potentially speciation. The dynamics of selection for mitonuclear function optimize fitness over generations, but the same selective processes also operate within generations, driving ageing and age‐related diseases. This coherent view of eukaryotic energetics offers striking insights into infertility and age‐related diseases. (shrink)

There are two intriguing paradoxes in molecular biology-the inconsistent relationship between organismal complexity and (1) cellular DNA content and (2) the number of protein-coding genes-referred to as the C-value and G-value paradoxes, respectively. The C-value paradox may be largely explained by varying ploidy. The G-value paradox is more problematic, as the extent of protein coding sequence remains relatively static over a wide range of developmental complexity. We show by analysis of sequenced genomes that the relative amount of non-protein-coding sequence increases (...) consistently with complexity. We also show that the distribution of introns in complex organisms is non-random. Genes composed of large amounts of intronic sequence are significantly overrepresented amongst genes that are highly expressed in the nervous system, and amongst genes downregulated in embryonic stem cells and cancers. We suggest that the informational paradox in complex organisms may be explained by the expansion of cis-acting regulatory elements and genes specifying trans-acting non-protein-coding RNAs. (shrink)

In bacteria, PriA protein, a conserved DEXH‐type DNA helicase, plays a central role in replication restart at stalled replication forks. Its unique DNA‐binding property allows it to recognize and stabilize stalled forks and the structures derived from them. Cells must cope with fork stalls caused by various replication stresses to complete replication of the entire genome. Failure of the stalled fork stabilization process and eventual restart could lead to various forms of genomic instability. The low viability of priA null (...) cells indicates a frequent occurrence of fork stall during normal growth that needs to be properly processed. PriA specifically recognizes the 3′‐terminus of the nascent leading strand or the invading strand in a displacement (D)‐loop by the three‐prime terminus binding pocket (TT‐pocket) present in its unique DNA binding domain. Elucidation of the structural basis for recognition of arrested forks by PriA should provide useful insight into how stalled forks are recognized in eukaryotes. (shrink)

Organisms and their genomes are mosaics of features of different evolutionary age. Older features are maintained by ‘negative’ selection and comprise part of the selective environment that has shaped the evolution of newer features by ‘positive’ selection. Body plans and body parts are among the most conservative elements of the environment in which genetic differences are selected. By this process, well-trodden paths of development constrain and direct paths of evolutionary change. Structuralism and adaptationism are both vindicated. Form plays a selective (...) role in the molding of form. (shrink)