The pituitary hormone prolactin (PRL) is best known for its role in the regulation of lactation. Recent evidence furthermore indicates PRL is required for normal reproduction in rodents. Here, we report on the insertion of two transposon-like DNA sequences in the human prolactin gene, which together function as an alternative promoter directing extrapituitary PRL expression. Indeed, the transposable elements contain transcription factor binding sites that have been shown to mediate PRL transcription in human uterine decidualised endometrial cells and (...) lymphocytes. We hypothesize that the transposon insertion event has resulted in divergent (pituitary versus extrapituitary) expression of prolactin in primates, and in differential actions of pituitary versus extrapituitary prolactin in lactation versus pregnancy respectively. Importantly, the TE insertion might provide a context for some of the conflicting results obtained in studies of PRL function in mice and man. (shrink)

A large number of previous reports described an effect of the pituitary hormone prolactin (PRL) on steroid hormone production by the adrenal cortex. However, those studies remained anecdotal and were never converted into a conceptual and mechanistic framework, let alone being translated into clinical care. In the light of our recently published landmark study where we described PRL signalling as a pivotal regulator of the sexually dimorphic adrenal phenotype in mouse and of adrenal androgen production in humans, we present (...) here the overarching hypothesis that PRL signalling increases the activity of Steroidogenic Factor‐1 (SF‐1/NR5A1), a transcription factor that has an essential role in adrenal gland development and function, to regulate adrenal cortex growth and hormonal production in physiological and pathological conditions. PRL can then be considered as a bona fide adrenocorticotropic hormone synergizing with ACTH in the endocrine control of adrenal cortex function. (shrink)

SummaryCross-sectional studies in Australia and the Philippines and a longitudinal prospective study in a selected Australian sample of breast-feeding mothers have shown that basal serum prolactin concentrations are elevated during 15–21 months of lactational amenorrhoea.A predictive model of serum PRL levels and return of cyclic ovarian activity during full breast-feeding, partial breast-feeding and weaning has been developed from the results of breast-feeding behaviour and serum PRL, gonadotrophin and oestradiol measurements in 34 mothers breast-feeding on demand for a mean of (...) 67 weeks.Breast-feeding patterns influence serum PRL levels. Important factors during full breast-feeding are the age of the baby, the longest interval between feeds at night and total 24-hr suckling time, and following the introduction of supplements, the mean interval between feeds, together with the total 24-hr suckling time and the number of solid supplements per day.The precise mechanisms whereby breast-feeding regulates cyclic ovarian activity remain unknown. Gonadotrophin secretion appears to be quantitatively normal, but qualitative changes, secondary to altered hypothalamic activity, may be the most important factor. A direct inhibitory effect of PRL on ovarian follicular development and steroidogenesis remains possible.Ovulation with a normal luteal phase is probable for 30% of breast-feeding mothers before the first menses, but is unlikely before 6 months, provided breast-feeding is frequent day and night.Measurement of serum PRL is a sensitive index of the return of menstruation and fertility during lactation in the population studied. (shrink)

The molecular evolution of pituitary growth hormone and prolactin in mammals shows two unusual features: episodes of markedly accelerated evolution and, in some species, complex families of related proteins expressed in placenta and resulting from multiple gene duplications. Explanations of these phenomena in terms of physiological adaptations seem unconvincing. Here, I propose an alternative explanation, namely that these evolutionary features reflect the use of the hormones (and their receptors) as viral receptors. Episodes of rapid evolution can then be explained (...) as due to “arms races” in which changes in the hormone lead to reduced interaction with the virus, and subsequent changes in the virus counteract this. Placental paralogues of the hormones could provide decoys that bind viruses, and protect the foetus against infection. The hypothesis implies that the extensive changes introduced into growth hormone, prolactin and their receptors during the course of mammalian evolution reflect viral interactions, not endocrine adaptations. (shrink)

The present study examines the physiological alterations in prolactin (PRL) messenger ribonucleic acid (mRNA) and serum PRL levels during the rat estrous cycle and the effed of naloxone, an endogenous opioid peptide receptor antagonist, on PRL gene expression during the rat estrous cycle. Adult female rats exhibiting at least two consecutive 4-day estrous cycles were used in this study. A single injection of naloxone (2mg/kg b.w.) or saline was given sc 30 mm prior to decapitation. Animals were sacrificed at (...) 10:00 h of each stage of the estrous cycle, and at 2-h intervals from 10:00 h to 20:00 h during the proestrus. PRL mRNA and serum PRL levels were determined by an RNA-blot hybridization with the rat PRL cDNA probe and by a PRL radioimmunoassay, respectively. PRL mRNA and serum PRL levels were not dramatically altered in the morning of each stage of diestrus I, II, and proestrus, and naloxone failed to modify the two parameters. During estrus naloxone clearly suppressed serum PRL levels, but it was unable to modify PRL mRNA levels. A more detailed examination of the proestrus stage revealed that PRL mRNA and serum PRL levels fluctuated as a function of time: PRL mRNA levels reached a maximum level at 12:00 h and gradually decreased until 18:00 h. PRL mRNA levels then rose at 20:00 h. No difference in PRL mRNA levels between the control and naloxone-treated groups was observed. Changes in serum PRL level during proestrus were conversely related to changes in PRL mRNA: serum PRL levels were low from 10:00 h to 14:00 h, then increased and reached a maximum level at 16:00-18:00 h. Following then, serum PRL levels were decreased. Naloxone was effective in suppressing the characteristic afternoon surge of PRL from 16:00 h to 20:00 h. These data clearly showed that alterations in PRL mRNA levels were conversely correlated with changes in serum PRL levels on proestrus, indicating differential regulation of PRL gene expression and secretion. (shrink)

Serum prolactin has been measured in single blood samples collected within the first 22 post-partum months from 97 nursing mothers from an urban area (Bukavu) of Zaïre. Nursing mothers are hyperprolactinemic, higher serum prolactin levels being associated with more frequent suckling episodes per day. Furthermore, serum prolactin declines rapidly in mothers who are giving the breast less than four times per day: the levels are within the normal range found in non-lactating women after the 6th post-partum month. (...) Among mothers giving the breast more than six times per day, serum prolactin does not decline significantly during the 1st post-partum year. (shrink)

Women’s preferences for several male traits, including voices, change over the menstrual cycle, but the proximate causes of these changes are unknown. This paper explores relationships between levels of estradiol, progesterone, luteinizing hormone, follicle stimulating hormone, prolactin, and testosterone (estimated using menstrual cycle information) and women’s preferences for male vocal masculinity in normally cycling and hormonally contracepting heterosexual females. Preferences for vocal masculinity decreased with predicted progesterone levels and increased with predicted prolactin levels in normally cycling—but not hormonally (...) contracepting—women. Adaptive explanations for menstrual variation in women’s preferences for masculine traits are discussed and evaluated in light of these findings. (shrink)

Human skin produces numerous neurohormones and neuropeptides. Recent evidence has shown that the neuroendocrine regulation of human skin biology also extends to keratins, the major structural components of epithelial cells. For example, thyrotropin‐releasing hormone, thyrotropin, opioids, prolactin, and cannabinoid receptor 1‐ligands profoundly modulate human keratin gene and protein expression in human epidermis and/or hair follicle epithelium in situ. Since selected keratins are now understood to exert important regulatory functions beyond mechanical stability, we argue that neuroendocrine pathways of keratin regulation (...) are important for maintaining skin and hair follicle homeostasis. This invites innovative neuroendocrine therapeutic interventions for skin disorders characterized by abnormal keratin expression, ranging from psoriasis to genodermatoses, and for promoting skin wound healing and hair growth. This strategy can be probed in simple, but instructive and readily available human skin and hair follicle organ culture assays as ideal models for exploring this new neuroendocrine frontier in translational epithelial biology. (shrink)

Deciduous trees remobilize the nitrogen in senescing leaves during the process of autumn colouration, which in many species is associated with increased concentrations of anthocyanins. Archetti1 and Hamilton and Brown2 observed that autumn colouration is stronger in tree species facing a high diversity of specialist aphids. They proposed a coevolution theory that the bright colours in autumn might provide an honest signal of defence commitment, thus deterring migrant aphids from settling on the leaves. So far, there have been very few (...) experimental results to support the hypothesis, and tree commitment to phenolics‐based defences has not shown direct protection against aphids. Predators and parasitoids have been found to be the major controllers of arboreal aphids. Indirect defences involve the emission of attractive volatile compounds that enhance the effectiveness of carnivorous enemies. The indirect defence hypothesis is presented to explain low aphid diversity on tree species that are green during autumn. The hypothesis suggests that green foliage can continue to produce herbivore‐inducible plant volatiles and maintain volatile‐based indirect plant defences against aphids until leaf abscission. BioEssays 30:889–896, 2008. © 2008 Wiley Periodicals, Inc. (shrink)

The transcription of rat prolactin and growth hormone genes in vitro requires a pituitary transcription factor, specific to certain cell types in the pituitary, which currently appears to be the PUF‐I/Pit‐1/GHF‐1 protein. This factor binds to cis‐regulatory elements in the 5′ region of both genes and exerts a positive influence on transcription initiation presumably by interacting with general transcription factors. The PUF‐I/Pit‐1/GHF‐1 transcriptional regulatory protein probably has an important role in not only the differentiation of the pituitary lactotroph/somatotroph cell (...) lineage; it is also expressed in the early development of the nervous system but its function there is less well documented. It appears to be one member of a family of trans‐activator proteins involved in differential gene expression in several cell types. (shrink)

Understanding the evolutionary role of environmentally induced phenotypic variation (i.e., plasticity) is an important issue in developmental evolution. A major physiological response to environmental change is cellular stress, which is counteracted by generic stress reactions detoxifying the cell. A model, stress‐induced evolutionary innovation (SIEI), whereby ancestral stress reactions and their corresponding pathways can be transformed into novel structural components of body plans, such as new cell types, is described. Previous findings suggest that the cell differentiation cascade of a cell type (...) critical to pregnancy in humans, the decidual stromal cell, evolved from a cellular stress reaction. It is hypothesized that the stress reaction in these cells was elicited ancestrally via inflammation caused by embryo attachment. The present study proposes that SIEI is a distinct form of plasticity‐based evolutionary change leading to the origin of novel structures rather than adaptive transformation of pre‐existing characters. (shrink)

This essay pursues the question of vegetal respiration in Presocratics’ doctrines in contrast to Aristotle’s categorical circumscription of this vital process to the blooded animals. It finds that epithelial respiration in DK31 B100 is central to Empedocles’ conception of plants’ breathing, linked to their fructification, deciduousness, and overall life preservation. It also discusses plants’ respiration in relation to their body temperature in Menestor, then, concludes by analyzing Democritus’ psychological doctrine, arguing that the intake of fiery atoms pertained to all living (...) beings, plants included. (shrink)

Why do humans menstruate while most mammals do not? Here, we present our answer to this long‐debated question, arguing that (i) menstruation occurs as a mechanistic consequence of hormone‐induced differentiation of the endometrium (referred to as spontaneous decidualization, or SD); (ii) SD evolved because of maternal–fetal conflict; and (iii) SD evolved by genetic assimilation of the decidualization reaction, which is induced by the fetus in non‐menstruating species. The idea that menstruation occurs as a consequence of SD has been proposed in (...) the past, but here we present a novel hypothesis on how SD evolved. We argue that decidualization became genetically stabilized in menstruating lineages, allowing females to prepare for pregnancy without any signal from the fetus. We present three models for the evolution of SD by genetic assimilation, based on recent advances in our understanding of the mechanisms of endometrial differentiation and implantation. Testing these models will ultimately shed light on the evolutionary significance of menstruation, as well as on the etiology of human reproductive disorders like endometriosis and recurrent pregnancy loss. (shrink)

SummaryThe effects of infant suckling patterns on the post-partum resumption of ovulation and on birth-spacing are investigated among the Gainj of highland New Guinea. Based on hormonal evidence, the median duration of lactational anovulation is 20·4 months, accounting for about 75% of the median interval between live birth and next successful conception. Throughout lactation, suckling episodes are short and frequent, the interval changing slowly over time, from 24 minutes in newborns to 80 minutes in 3-year olds. Maternal serum prolactin (...) concentrations decline in parallel with the changes in suckling patterns, approaching the level observed in non-nursing women by about 24 months post-partum. A path analysis indicates that the interval between suckling episodes is the principal determinant of maternal prolactin concentration, with time since parturition affecting prolactin secretion only in so far as it affects suckling frequency. The extremely prolonged contraceptive effect of breast-feeding in this population thus appears to be due to a slow decline in suckling frequency with time since parturition and absence of a decline over time in hypothalamic–pituitary responsiveness to the suckling stimulus. (shrink)

Bringing Flowers HomeWe try to put a bandage on the wound,offering a vague apology:Forgive me, distant wars, for bringing flowers home.Towers turn out to have been built on sand.Regimes collapse. No use in asking whywe ripped the bandage off that bleeding wound.An earthquake followed by a hurricane,fires, floods: they've passed some of us by.Us. And who is we? And what is home?Last week an enormous yellow moonhung low in a corner of the sky.Beauty is no bandage for the wound,hole in (...) the future much too big to mendor even to imagine, though we tryto camouflage it, bringing flowers home.You said, when we were talking of the end,that no one teaches us to say goodbye,or how to ease the bandage from the wound.Forgive me, death. I brought these flowers home.Moving the PianoCompact, gleaming, black and white,this sturdy Yamaha uprightstood staunchly in one room for yearsuntil, maneuvered through several doorstoday by two young slender menand up a ramp into their van,it ventured briefly out into the world again.The change of space, the space of change:the walls look naked, empty, strange.Heavy has given way to light.Habitual soliditytoo familiar to seeyields to possibilitytoo unfamiliar to see.Late and early, early, late,end, beginning—all are swirledinto a mist that veils the world.The black and white of status quoblends to a color I don't know,transition that I cannot name,but I salute it all the same.Goodbye, piano, and hello.So where is the piano going?Where will it find another life,music and memories unpackedin an unfolding second act?North Carolina, near a riverwhose stream, like time, is always flowing.My son lives there with his wife.Beloved, nothing is forever.You can't step twice into this life.Nap at Stony PointMy cousin and my friendon their respective recent deathbedsslid from my mind. I noticedthe scarlet splash of a cardinal perched on a cannonon a bluff above the Hudson.I lay down on a picnic table,sun on my face, five turkey vulturescircling overhead, and closed my eyes.And when I opened them I felt as pleasedas if I had completed some needful taskinstead of having forgottenhow my friend in January and my cousin in March,both of them alert and wry and tranquil,had faced what each of them clearly saw approaching—more, had recognized and greeted it,instead of ignoring it by looking through it,the way some people, even iftheir office is two doors down the hall,look right through you, pretending not to see you.Or maybe they don't see youany more than one envisions deathon a sunny April afternoon.The Last Lecture HallTheaters that were never ours,classrooms empty and refill.Nor do the trees belong to us.We cross the stage and disappearor venture in among the treesand lose ourselves there.Feverish categories blur.Genre distinctions: what for?The empty theater becomesa lecture hall. A classroom morphsinto a forest murmuringwith voices. Words pelt down like rainor rise like mist and dissipate.The rustling trees swell to a roar.But they were never still.Theater, classroom, maple, fir:feverish categories blur,presences pressing through the veilof the phenomenal;a leopard padding down the aisle.Tiger-masked students fill the seatsof the amphitheater.The old professor, looking outover the upturned faces, said“You are all allegoricalfigures to me. I will not learnyour names.” Did the students laugh?Tragedy, satire, comedy:genres are deciduous.Modes blur, leaves spin and fall.The leaves of memory seemed to makeA mournful rustling in the dark(Longfellow, “The Fire of Driftwood”).Lights go on in the theater.Class is over. We stumble out.The GatesWhen I woke up I had walked through a gate.I looked around the room—trickle or torrent, stepping into time—and bent my head to drink at a black stream.I look around a roomthick with the dust of after and before.Am I meant to drink from this black stream?My lips are dry,thick with the crust of after and before,gate of ivory and gate of horn.My lips are dry, I'm thirsty.Heat, cold, fire, snow, sun.Gate of ivory and gate of horn:to cross a threshold ends one story(firelight; snow squeaking; winter sun)and begins another.To cross a threshold ends one story(ever after? or a transformation?)and begins anotherthere is no law compelling us to enter.Ever after or a transformation.Torrent, trickle: we set foot in time,but there's no law compelling us to enterstory once we've latched the gate of dream.FilamentsYour past is thickening. You can seeits filaments, as carefullyyou begin to part the strands(they're all connected) with both hands,and clear a path. Now warilyenter the web—not all the way,but toward some kind of clarity.We have been rightly taught that wecan't finish, but must do, the work.Partway through the leafy murk,crisscrossing dapple of the trees,so tough and so precarious,you find yourself in the dawn air,the circle's center everywhere.Along the PromenadeReading a book about transitioningin the twenty-first-century meaning of the wordblends with plans for my son's upcoming weddingand scraps of conversation overheardat the Japanese-themed street fair today.Somnambulists along the promenadefloat in the warm currents of Broadway,eat talk look linger in the sun and shade.Then to the park: October leaves still green(climate change or merely Indian summer?).Snatched memories, I catch them on the wing:Samos Septembers, pomegranate tree,lemon tree, okra, a chameleon,the little summer of Saint Dimitri,they called it. All this happened; but to me?Streams of conversation flowing by.The sound artist described his work like this(if work is the right word): “Accidentallyuploading seemingly private messages,”which describes, also, dreams and poetry,the drifting crowd, incessant carousel,city and weather, time and holiday,all lived, palped, tasted, tested, overheard.Somnambulists along the promenadehave set up booths, their dreams... Bookending my dawn dream: symmetricalsoaking sponges dripping... DNA?Destiny, temperament, personality:the cards we're dealt and that we have to play,except we now can change them gradually.Transition: he or she or rather they,constructed, deconstructed, rearranged,the tarot spread of genealogy,inheritance as aleatoric play.We walked west to Eleventh Avenue,drawn by rumors of Ad Reinhardt's blue,which buzzed and throbbed. Stand still: my head was spinning.Allusions to water or to sky,dense, deep, alarming, ending or beginning... I sat awhile and watched the crowd glide by,enchanted promenaders all drawn inon the exhibition's last dayby the silence's cerulean humming.And then they climbed the stairs, and so did we,to lighter textures on an upper floorwhere Ruth Asawa's baskets in midairweightlessly demonstrated gravity,twigs, trees, crowns, bubbles dancing in white space.Next week my class will read “On Being Ill.”“Blogs,” I'll tell them, is the word we nowuse, not “essay,” for the moving mind,that saunterer who takes note and leaves behindand doubles back and ponders and regretsamidst the wash of vision, the flowand tidal pull of what we see and know,what we've dreamed, what we have said and heard,the thrumming colors and the floating crowd,as if the bubbly brew of sunny dayand anxious dreams could somehow all be caughtup in one enormous, one all-encompassing word. (shrink)

The precocious induction in vivo and in culture of insect and amphibian metamorphosis by exogenous ecdysteroids and thyroid hormones, and its retardation or inhibition by juvenile hormone and prolactin, respectively, has allowed the analysis of such diverse processes of post‐embryonic development as morphogenesis, tissue remodelling, functional reorganization, and programmed cell death. Metamorphosis in vertebrates also shares many similarities with mammalian development in the late foetal and perinatal period. This review describes the regulation of expression of some of the ‘adult’ (...) gene products during metamorphosis in invertebrates and vertebrates. Recent studies on metamorphosis have revealed the important role played by auto‐induction of hormone receptor genes, based on which a model will be presented to explain the activation of ‘downstream’ genes which give rise to the adult phenotype. It will also be argued that metamorphosis is an ideal model for analyzing some of the major mechanisms governing post‐embryonic development. (shrink)

An extensive, and controversial, literature concluding that prolactin (PRL), growth hormone (GH), insulin-like growth factor-I (IGF-I), and thyroid hormones are critical immunoregulatory factors has accumulated. However, recent studies of mice deficient in the production of these hormones or expression of their receptors indicate that there are only a few instances in which these hormones are required for lymphocyte development or antigen responsiveness. Instead, a case is made that their primary role is to counteract the effects of negative immunoregulatory factors, (...) such as glucocorticoids, which are produced when the organism is subjected to major stressors. The immunoprotective actions of PRL, GH, IGF-I, and/or thyroid hormones in these instances may ensure immune system homeostasis and reduce the susceptibility to stress-induced disease. These immuno-enhancing effects could be exploited clinically in instances where the immune system is depressed due to illness or various treatment regimens. BioEssays 23:288–294, 2001. © 2001 John Wiley & Sons, Inc. (shrink)

Attention has become increasingly focused in recent years on the role agri-food system transformations have played in driving the global diet-related chronic disease burden. Identifying the role played by the food-consuming industries (predominantly large manufacturers, processors, distributors, and retailers) in particular, and identifying possibilities to facilitate healthier diets through intervening in these industries, have been identified as a research priority. This paper explores the potential for one promising analytic framework—the nutrition-oriented value chain approach—to contribute to this area, drawing on recent (...) insights from the global value chain (GVC) literature to develop an institutionally-enriched approach. The research focused on a canned deciduous fruit value chain linking growers, processors, and retailers in South Africa and Australia. Findings reveal the multiple drivers which have converged to shape this value chain over time, and the key actors which are influencing product availability, composition, price, and promotion within this sector. With its emphasis on identifying implications for end-consumption, rather than economic outcomes within the chain, nutrition-oriented value chain research represents a significant shift in focus for the GVC framework. Therefore, an immediate opportunity for further research is to extend the analytic framework to primary research on end-consumption behaviours. (shrink)

The article presents the results of analysis of nine wooden utensils of the Bronze and Early Iron Ages in comparison with previous analysis of different authors. In eight cases remains were represented by deciduous trees. Comparison of this results with data from other investigators allowed to conclude that for making objects from wood used mainly local breeds. When selecting trees for making utensils, old masters have used certain principles such as ease of cutting and aesthetic preferences. For the manufacture of (...) wooden utensils, pastoral nomads used mostly local wood that grew in gullies and floodplains. Most often for the manufacture of wooden utensils used maple, which is recorded in the Catacomb monuments, Zrubna, Scythian and Sarmatian burials. The generally accepted view is of the greatest accessibility of oak as a material for the manufacture of wooden utensils. However, our analysis and findings of other studies suggest limited use of wood for making utensils. Only in one case, for making fixed tray was used oak bark. However, generally we have to assume that the old masters avoided the use of oak wood for cutting wooden utensils due to its physical properties and considering that the tools were quite simple for working with brittle kinds of wood. In two cases the data shows that for producing of the bowl chestnut wood was utilized. In the Steppe zone the willow and birch bark were broadly widespread. They could be used to make baskets and birch products, however, we do not have the results of relevant analyzes to talk about it with confidence. (shrink)

It is posited that the initiating event of amphibian regeneration of a limb, is retrodifferentiation* of what are to become the developing cells of the blastema. These cells reiterate a larval or premetamorphic ontogenic repertoire, induced by elevated levels of prolactin with adequate innervation. Subsequent redifferentiation of the blastema cells occurs, controlled by thyroxine and innervation.This temporal displacement of cellular morphologic characters in regeneration should be looked upon as a function of the ability to reiterate larval characters and subsequently (...) metamorphose. If correct, this would explain why amphibians which metamorphose only once, lose the ability to postmetamorphically regenerate. An exception to this,Xenopus laevis, an anuran which can epimorphically regenerate, to some extent, will be discussed.[/p]. (shrink)

A new interpretation of human menstruation is presented, resulting from a cross‐disciplinary investigation of evolution, developmental biology, and physiology. A process evolutionarily associated with childbirth expresses itself as menstruation in women for whom frequent and continual failure to conceive has become the default situation. In humans and Old World primates, contractile uterine spiral arterioles evolved as the complement of the highly invasive hemochorionic placenta and is the selected phenotype. Placental progesterone withdrawal during the last stage of birth leads to arrested (...) blood flow through maternal spiral arterioles, allowing detachment of the deciduous placenta with minimal maternal hemorrhage. In nonpregnant females, progesterone withdrawal from a degenerating corpus luteum initiates menstruation and stops blood flow through uterine spiral arterioles. Both events share similar physiological mechanisms and sequences. This explanation may improve our understanding of a recurrent event experienced by half of the human population and for a quarter of their adult reproductive life. (shrink)

In March 2022 the US Food and Drug Administration (FDA) published a risk assessment of a recent animal gene editing proposal submitted by Acceligen™. The proposal concerned the possibility of changing the cattle genome to obtain a slicker, shorter hair coat. Using CRISPR-Cas9 it was possible to introduce an intentional genomic alteration (IGA) to the prolactin receptor gene (PRLR), thereby producing PRLR-SLICK cattle. The goal was to diminish heat stress in the cattle by enhancing their heat-tolerance. With regard to (...) unintended alterations (i.e., off-target effects), the FDA stated that the IGA posed a low, but still present, risk to animal safety. The aim of this article is to present some initial insights into the welfare issues raised by PRLR-SLICK cattle by addressing the question: Do SLICK cattle have better welfare than non-SLICK cattle when exposed to heat stress? Two potential welfare concerns are examined. The first is pleiotropy, an issue that arises when one gene affects multiple traits. Given the pleiotropic nature of prolactin, it has been suggested that the IGA for SLICK cattle may also affect their hepatic and other functions. The second concern relates not primarily to direct effects on cattle health, but rather to the indirect risk that this more heat-tolerant animal would just be used in the livestock sector under farming conditions that are such that the net welfare improvement would be non-existent. (shrink)

Recent studies have yielded new insights into the critical importance of adequate vitamin D3 intake and metabolism. Investigations of the actions of 1,25‐dihydroxyvitamin D3 (calcitriol) on novel target tissues has revealed that this hormone has functions other than its recognized action in regulating blood calcium and phosphate levels. Reports have characterized calcitriol receptors and activities in organs and tissues as diverse as pancreas, skeletal and heart muscle, blood cells, brain, skin, pituitary, parathyroid, kidney, bone and intestine. These studies suggest functions (...) for calcitriol as varied as the regulation of insulin and prolactin secretion, muscle contractility, immune cell metabolism, melanin synthesis and differentiation of blood cells. This information may ultimately help us to understand the etiologies of several kinds of organ dysfunction and lead to the development of tissue‐specific agents for new therapies. (shrink)