Standards of Care for the Health of Transgender and Gender Diverse People, Version 8

Background: Transgender healthcare is a rapidly evolving interdisciplinary field. In the last decade, there has been an unprecedented increase in the number and visibility of transgender and gender diverse (TGD) people seeking support and gender-affirming medical treatment in parallel with a significant rise in the scientific literature in this area. The World Professional Association for Transgender Health (WPATH) is an international, multidisciplinary, professional association whose mission is to promote evidence-based care, education, research, public policy, and respect in transgender health. One of the main functions of WPATH is to promote the highest standards of health care for TGD people through the Standards of Care (SOC). The SOC was initially developed in 1979 and the last version (SOC-7) was published in 2012. In view of the increasing scientific evidence, WPATH commissioned a new version of the Standards of Care, the SOC-8. Aim: The overall goal of SOC-8 is to provide health care professionals (HCPs) with clinical guidance to assist TGD people in accessing safe and effective pathways to achieving lasting personal comfort with their gendered selves with the aim of optimizing their overall physical health, psychological well-being, and self-fulfillment. Methods: The SOC-8 is based on the best available science and expert professional consensus in transgender health. International professionals and stakeholders were selected to serve on the SOC-8 committee. Recommendation statements were developed based on data derived from independent systematic literature reviews, where available, background reviews and expert opinions. Grading of recommendations was based on the available evidence supporting interventions, a discussion of risks and harms, as well as the feasibility and acceptability within different contexts and country settings. Results: A total of 18 chapters were developed as part of the SOC-8. They contain recommendations for health care professionals who provide care and treatment for TGD people. Each of the recommendations is followed by explanatory text with relevant references. General areas related to transgender health are covered in the chapters Terminology, Global Applicability, Population Estimates, and Education. The chapters developed for the diverse population of TGD people include Assessment of Adults, Adolescents, Children, Nonbinary, Eunuchs, and Intersex Individuals, and people living in Institutional Environments. Finally, the chapters related to gender-affirming treatment are Hormone Therapy, Surgery and Postoperative Care, Voice and Communication, Primary Care, Reproductive Health, Sexual Health, and Mental Health. Conclusions: The SOC-8 guidelines are intended to be flexible to meet the diverse health care needs of TGD people globally. While adaptable, they offer standards for promoting optimal health care and guidance for the treatment of people experiencing gender incongruence. As in all previous versions of the SOC, the criteria set forth in this document for gender-affirming medical interventions are clinical guidelines; individual health care professionals and programs may modify these in consultation with the TGD person.

Suppression of ovarian hormones in adolescent rats has no effect on anxiety-like behaviour or c-fos activation in the amygdala

In humans, sex differences in mood disorders emerge during adolescence, with prevalence rates being consistently higher in females than males. It has been hypothesised that exposure to endogenous ovarian hormones during adolescence enhances the susceptibility of females to mood disorders from this stage of life onwards. However, experimental evidence in favour of this hypothesis is lacking. In the present study, we examined the long-term effects of suppressing adolescent gonadal hormone levels in a group of female Lister-hooded rats via administration of a gonadotrophin-releasing hormone antagonist (Antide; administered on postnatal day [PND] 28 and 42) compared to control females and males (n = 14 per group). We predicted that, in adulthood, Antide-treated female rats would exhibit more male-like behaviour than control females in novel environments (elevated-plus maze, open field and light-dark box), in response to novel objects and novel social partners, and in an acoustic startle task. Progesterone and luteinising hormone assays (which were conducted on blood samples collected on PND 55/56 and 69/70) confirmed that the hypothalamic-pituitary-gonadal axis was temporarily suppressed by Antide treatment. In addition, Antide-treated females were found to exhibit a modest pubertal delay, as measured by vaginal opening, which was comparable in length to the pubertal delay that has been induced by adolescent exposure to alcohol or stress in previous studies of female rats. However, Antide-treated females did not substantially differ from control females on any of the behavioural tests, despite the evidence for predicted sex differences in some measures. Following the acoustic startle response task, all subjects were culled and perfused, and c-Fos staining was conducted in the medial and basolateral amygdala, with the results showing no significant differences in cell counts between the groups. These findings suggest that ovarian hormone exposure during adolescence does not have long-term effects on anxiety-related responses in female rats.

Gender Equality and Gender Gaps in Mathematics Performance

In a recent analysis of mathematics performance (Eriksson et al. 2020), national gender egalitarian values were positively associated with an increase in the average mathematics scores of high-school boys relative to girls. This study highlights that progressive gender egalitarian values at a national level might not translate into equality of opportunity at an individual level.

A specialised pollination system using nectar-seeking thynnine wasps in Caladenia nobilis (Orchidaceae)

Caladenia is a diverse Australian genus that is exceptional among orchids in having both species pollinated by food-seeking and sexually deceived insects. Here, we investigated the pollination of Caladenia nobilis, a species predicted to be food-deceptive due to its large, cream-coloured and apparently nectarless flowers. Pollinator observations were made using experimental clumps of flowers. Measurements of floral colour were undertaken with a spectrometer, nectar was tested using GC-MS, and reproductive success was quantified for 2 years. While C. nobilis attracted nine species of insect, only males of the thynnine wasp Rhagigaster discrepans exhibited the correct size and behaviour to remove and deposit pollen. Male R. discrepans attempted to feed from the surface of the labellum, often crawling to multiple flowers, but showed no evidence of sexual attraction. Most flowers produced little or no nectar, although some may provide enough sucrose to act as a meagre reward to pollinators. Floral colouration was similar to a related Caladenia species pollinated by sexual deception, although the sexually deceptive species had a dull-red labellum. Reproductive success was generally low and highly variable between sites and years. In addition to most visitors being of inappropriate size for pollinia removal, the lack of response to the orchid by several co-occurring species of thynnine wasp suggests filtering of potential pollinators at the attraction phase. Our discovery of a pollination strategy that may be intermediate between food deception and food reward raises the question, how many putatively rewardless orchids actually produce meagre amounts of nectar?

Social experience during adolescence in female rats increases 50 kHz ultrasonic vocalizations in adulthood, without affecting anxiety-like behavior

Adolescents are highly motivated to engage in social interactions, and researchers have hypothesized that positive social relationships during adolescence can have long term, beneficial effects on stress reactivity and mental well-being. Studies of laboratory rodents provide the opportunity to investigate the relationship between early social experiences and later behavioral and physiological responses to stressors. In this study, female Lister-hooded rats (N = 12 per group) were either (a) provided with short, daily encounters (10 min/day) with a novel partner during mid-adolescence (postnatal day 34-45; "social experience," SE, subjects) or (b) underwent the same protocol with a familiar cagemate during mid-adolescence ("control experience," CE, subjects), or (c) were left undisturbed in the home cage (non-handled "control," C, subjects). When tested in adulthood, the groups did not differ in behavioral responses to novel environments (elevated plus maze, open field, and light-dark box) or in behavioral and physiological (urinary corticosterone) responses to novel social partners. However, SE females emitted significantly more 50 kHz ultrasonic vocalizations than control subjects both before and after social separation from a familiar social partner, which is consistent with previous findings in male rats. Thus, enhanced adolescent social experience appears to have long-term effects on vocal communication and could potentially modulate adult social relationships.

Human mate-choice copying is domain-general social learning

Women appear to copy other women’s preferences for men’s faces. This ‘mate-choice copying’ is often taken as evidence of psychological adaptations for processing social information related to mate choice, for which facial information is assumed to be particularly salient. No experiment, however, has directly investigated whether women preferentially copy each other’s face preferences more than other preferences. Further, because prior experimental studies used artificial social information, the effect of real social information on attractiveness preferences is unknown. We collected attractiveness ratings of pictures of men’s faces, men’s hands, and abstract art given by heterosexual women, before and after they saw genuine social information gathered in real time from their peers. Ratings of faces were influenced by social information, but no more or less than were images of hands and abstract art. Our results suggest that evidence for domain-specific social learning mechanisms in humans is weaker than previously suggested.

Sex differences in the use of social information emerge under conditions of risk

Social learning provides an effective route to gaining up-to-date information, particularly when information is costly to obtain asocially. Theoretical work predicts that the willingness to switch between using asocial and social sources of information will vary between individuals according to their risk tolerance. We tested the prediction that, where there are sex differences in risk tolerance, altering the variance of the payoffs of using asocial and social information differentially influences the probability of social information use by sex. In a computer-based task that involved building a virtual spaceship, men and women (N = 88) were given the option of using either asocial or social sources of information to improve their performance. When the asocial option was risky (i.e., the participant’s score could markedly increase or decrease) and the social option was safe (i.e., their score could slightly increase or remain the same), women, but not men, were more likely to use the social option than the asocial option. In all other conditions, both women and men preferentially used the asocial option to a similar degree. We therefore found both a sex difference in risk aversion and a sex difference in the preference for social information when relying on asocial information was risky, consistent with the hypothesis that levels of risk-aversion influence the use of social information.

Ultrasonic vocalizations of female Norway rats (Rattus norvegicus) in response to social partners

In many species of animals, male vocalizations function to attract mating partners and coordinate sexual interactions. Whereas male vocalizations have been well studied in several species, the function of female vocalizations in mating contexts is not fully understood. In Norway rats (Rattus norvegicus), both males and females produce ultrasonic vocalizations (USVs) during sexual encounters with opposite sex partners. The aim of this study was to test the hypothesis that female vocalizations play a role in sociosexual interactions by examining how rates of 50 kHz USV production vary in relation to the sex and gonadal status of the partner, and by examining whether the proportion of frequency modulated (FM) and constant frequency calls differs between these categories of social partner. The results showed that females produced a higher total number of 50 kHz USVs to intact males than castrated males, and produced similar numbers of calls to both categories of females. Females also produced a higher proportion of FM calls to male partners than to female partners, and spent more time in the vicinity of male than female partners, regardless of the partners' gonadal status. Female USVs therefore potentially provide a measure of sexual motivation and may function to promote female mate choice in this species with multimale mating and a high risk of infanticide.

Peri-pubertal exposure to testicular hormones organizes response to novel environments and social behaviour in adult male rats

Previous research has shown that exposure to testicular hormones during the peri-pubertal period of life has long-term, organizational effects on adult sexual behaviour and underlying neural mechanisms in laboratory rodents. However, the organizational effects of peri-pubertal testicular hormones on other aspects of behaviour and brain function are less well understood. Here, we investigated the effects of manipulating peri-pubertal testicular hormone exposure on later behavioural responses to novel environments and on hormone receptors in various brain regions that are involved in response to novelty. Male rodents generally spend less time in the exposed areas of novel environments than females, and this sex difference emerges during the peri-pubertal period. Male Lister-hooded rats (Rattus norvegicus) were castrated either before puberty or after puberty, then tested in three novel environments (elevated plus-maze, light-dark box, open field) and in an object/social novelty task in adulthood. Androgen receptor (AR), oestrogen receptor (ER1) and corticotropin-releasing factor receptor (CRF-R2) mRNA expression were quantified in the hypothalamus, hippocampus and medial amygdala. The results showed that pre-pubertally castrated males spent more time in the exposed areas of the elevated-plus maze and light-dark box than post-pubertally castrated males, and also confirmed that peri-pubertal hormone exposure influences later response to an opposite-sex conspecific. Hormone receptor gene expression levels did not differ between pre-pubertally and post-pubertally castrated males in any of the brain regions examined. This study therefore demonstrates that testicular hormone exposure during the peri-pubertal period masculinizes later response to novel environments, although the neural mechanisms remain to be fully elucidated.

Comment: Beyond “Evolutionary versus Social”: Moving the Cycle Shift Debate Forward

Wood, Kressel, Joshi, and Louie (2014) thoroughly evaluate the evidence for menstrual cycle shifts in ratings of several male characteristics and conclude that their analyses fail to provide supportive evidence for consistent cycle effects. The topic of menstrual cycle shifts in mate preferences has been strongly debated, with disagreements over both scientific content and practice. Here, we attempt to take a step back from these acrimonious exchanges and focus instead on how to interpret menstrual cycle shifts in mate preference tasks, independently from the question of when, or if, task performance varies with cycle stage. A greater consideration of domain-general mechanisms could provide an opportunity for investigating how evolved predispositions interact with socially transmitted information in biasing women’s responses on mate preference tasks.

Sex differences in interpretation bias in adolescents

Interpretation biases, in which ambiguous information is interpreted negatively, have been hypothesized to place adolescent females at greater risk of developing anxiety and mood disorders than same-aged males. We tested the hypothesis that adolescent girls interpret ambiguous scenarios more negatively, and/or less positively, than same-aged males using the Adolescent Interpretation and Belief Questionnaire (N = 67, 11-15 years old). We also tested whether adolescent girls and boys differed in judging positive or negative interpretations to be more believable and whether the scenario content (social vs. non-social) affected any sex difference in interpretation bias. The results showed that girls had higher average negative interpretation scores than boys, with no sex differences in positive interpretation scores. Girls and boys did not differ on which interpretation they found to be most believable. Both sexes reported that positive interpretations were less likely to come to mind, and were less believable, for social than for non-social scenarios. These results provide preliminary evidence for sex differences in interpretation biases in adolescence and support the hypothesis that social scenarios are a specific source of anxiety to this age group. A greater understanding of the aetiology of interpretation biases will potentially enhance sex- and age-specific interventions for anxiety and mood disorders.

The Serious Business of Play Cambridge University Press, Cambridge, 2013. 165 pp. $85, £55. ISBN 9781107015135. Paper, $34.99, £21.99. ISBN 9781107689343

Surveying the roles that playful behavior fills in development; Bateson and Martin pay particular attention to its influence on cognitive abilities.

Steroid hormones, stress and the adolescent brain: a comparative perspective

Steroid hormones, including those produced by the gonads and the adrenal glands, are known to influence brain development during sensitive periods of life. Until recently, most brain organisation was assumed to take place during early stages of development, with relatively little neurogenesis or brain re-organisation during later stages. However, an increasing body of research has shown that the developing brain is also sensitive to steroid hormone exposure during adolescence (broadly defined as the period from nutritional independence to sexual maturity). In this review, we examine how steroid hormones that are produced by the gonads and adrenal glands vary across the lifespan in a range of mammalian and bird species, and we summarise the evidence that steroid hormone exposure influences behavioural and brain development during early stages of life and during adolescence in these two taxonomic groups. Taking a cross-species, comparative perspective reveals that the effects of early exposure to steroid hormones depend upon the stage of development at birth or hatching, as measured along the altricial-precocial dimension. We then review the evidence that exposure to stress during adolescence impacts upon the developing neuroendocrine systems, the brain and behaviour. Current research suggests that the effects of adolescent stress vary depending upon the sex of the individual and type of stressor, and the effects of stress could involve several neural systems, including the serotonergic and dopaminergic systems. Experience of stressors during adolescence could also influence brain development via the close interactions between the stress hormone and gonadal hormone axes. While sensitivity of the brain to steroid hormones during early life and adolescence potentially leaves the developing organism vulnerable to external adversities, developmental plasticity also provides an opportunity for the developing organism to respond to current circumstances and for behavioural responses to influence the future life history of the individual.

Effects of suppressing gonadal hormones on response to novel objects in adolescent rats

Human adolescents exhibit higher levels of novelty-seeking behaviour than younger or older individuals, and novelty-seeking is higher in males than females from adolescence onwards. Gonadal hormones, such as testosterone and estradiol, have been suggested to underlie age and sex difference in response to novelty; however, empirical evidence in support of this hypothesis is limited. Here, we investigated whether suppressing gonadal hormone levels during adolescence affects response to novelty in laboratory rats. Previously, we have shown that male adolescent Lister-hooded rats (postnatal day, pnd, 40) exhibit a stronger preference than same-aged females for a novel object compared to a familiar object. In the current study, 24 male and 24 female Lister-hooded rats were administered with Antide (a gonadotrophin-releasing hormone antagonist), or with a control vehicle solution, at pnd 28. Antide provided long-term suppression of gonadal hormone production, as confirmed by ELISA assays and measurement of internal organs. Response to novel objects was tested at pnd 40 in Antide-treated and control subjects using a 'novel object recognition' task with a short (2-minute) inter-trial interval. In support of previous findings, control males exhibited a stronger preference than control females for novelty when presented with a choice of objects. Antide-treated males exhibited a significantly lower preference for novel objects compared to control males, whilst Antide-treated females did not differ significantly from control females in their preference for novelty. Antide treatment did not affect total time spent interacting with objects. We discuss how gonadal hormones might influence sex differences in preference for novelty during adolescence.

Darwin in mind: new opportunities for evolutionary psychology

Evolutionary Psychology (EP) views the human mind as organized into many modules, each underpinned by psychological adaptations designed to solve problems faced by our Pleistocene ancestors. We argue that the key tenets of the established EP paradigm require modification in the light of recent findings from a number of disciplines, including human genetics, evolutionary biology, cognitive neuroscience, developmental psychology, and paleoecology. For instance, many human genes have been subject to recent selective sweeps; humans play an active, constructive role in co-directing their own development and evolution; and experimental evidence often favours a general process, rather than a modular account, of cognition. A redefined EP could use the theoretical insights of modern evolutionary biology as a rich source of hypotheses concerning the human mind, and could exploit novel methods from a variety of adjacent research fields.

Evolutionary accounts of human behavioural diversity

Human beings persist in an extraordinary range of ecological settings, in the process exhibiting enormous behavioural diversity, both within and between populations. People vary in their social, mating and parental behaviour and have diverse and elaborate beliefs, traditions, norms and institutions. The aim of this theme issue is to ask whether, and how, evolutionary theory can help us to understand this diversity. In this introductory article, we provide a background to the debate surrounding how best to understand behavioural diversity using evolutionary models of human behaviour. In particular, we examine how diversity has been viewed by the main subdisciplines within the human evolutionary behavioural sciences, focusing in particular on the human behavioural ecology, evolutionary psychology and cultural evolution approaches. In addition to differences in focus and methodology, these subdisciplines have traditionally varied in the emphasis placed on human universals, ecological factors and socially learned behaviour, and on how they have addressed the issue of genetic variation. We reaffirm that evolutionary theory provides an essential framework for understanding behavioural diversity within and between human populations, but argue that greater integration between the subfields is critical to developing a satisfactory understanding of diversity.

Ontogeny of sex differences in response to novel objects from adolescence to adulthood in lister-hooded rats

In humans, novelty-seeking behavior peaks in adolescence and is higher in males than females. Relatively, little information is available regarding age and sex differences in response to novelty in rodents. In this study, male and female Lister-hooded rats were tested at early adolescence (postnatal day, pnd, 28), mid-adolescence (pnd 40), or early adulthood (pnd 80) in a novel object recognition task (n = 12 males/females per age group). Males displayed a higher preference for the novel object than females at mid-adolescence, with no sex difference at early adolescence. Adult females interacted with the novel object more than adult males, but not when side biases were removed. Sex differences at mid-adolescence were not found in other measures, suggesting that the difference at this age was specific to situations involving choice of novelty. The results are considered in the context of age- and sex-dependent interactions between gonadal hormones and the dopamine system. © 2011 Wiley Periodicals, Inc. Dev Psychobiol 53:670–676, 2011.

The ontogeny of anxiety-like behavior in rats from adolescence to adulthood

In human beings, susceptibility to anxiety disorders can be relatively high during adolescence. Understanding the ontogeny of anxiety-like behavior in laboratory rodents has implications for developing anxiolytic drugs that are suitable for this age group. Given the dearth of information about adolescent rodents, this study examined the response of both male and female adolescent, late adolescent, young adult, and older adult rats to three tests of anxiety-like behavior: the emergence test (ET), open field (OF), and elevated plus-maze (EPM). The results showed that adolescent rats exhibited a higher anxiety-like response than adults on each test; the amount of locomotion in the OF and percentage of time spent on the open arms of the EPM increased across the age groups, while older adult rats made the fewest start box re-entries in the ET. These results support the hypothesis that adolescent rats have a more pronounced response to stressors than do adults.

The ontogeny of exploratory behavior in male and female adolescent rats (Rattus norvegicus)

During adolescence, rats gain independence from their mothers and disperse from the natal burrow, with males typically dispersing further than females. We predicted that, if dispersal patterns are associated with responsiveness to novelty, exploratory behavior in novel environments would increase across adolescence, and males would explore more than females. Alternatively, females might explore more than males, if females are more motivated than males to learn about the immediate environment or if females have poorer spatial abilities than males. Twenty-five male and 21 female rats were exposed to two novel environments (open field and elevated plus-maze) during early, mid-, or late adolescence. Total locomotion and amount of exploration directed towards aversive areas increased across adolescence, even when body weight was included as a covariate. Female adolescents locomoted more and spent more time exploring aversive areas than males. Developmental changes in neural function potentially underlie age and sex differences in exploratory behavior. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 513–520, 2009.

Caring Cooperators The Evolutionary Origins of Mutual Understanding Harvard University Press, Cambridge, MA, 2009. 430 pp. $29.95, £19.95, €21. ISBN 9780674032996

Hrdy argues that human capacity for understanding arose from the cooperative nature of our "complicated and contingent form of childrearing."

Bateman's principles and human sex roles

In 1948, Angus J. Bateman reported a stronger relationship between mating and reproductive success in male fruit flies compared with females, and concluded that selection should universally favour ‘an undiscriminating eagerness in the males and a discriminating passivity in the females’ to obtain mates. The conventional view of promiscuous, undiscriminating males and coy, choosy females has also been applied to our own species. Here, we challenge the view that evolutionary theory prescribes stereotyped sex roles in human beings, firstly by reviewing Bateman's principles and recent sexual selection theory and, secondly, by examining data on mating behaviour and reproductive success in current and historic human populations. We argue that human mating strategies are unlikely to conform to a single universal pattern.

Local resource competition and local resource enhancement shape primate birth sex ratios

Sex ratio theory provides a powerful source of testable predictions about sex allocation strategies. Although studies of invertebrates generally support predictions derived from the sex ratio theory, evidence for adaptive sex ratio biasing in vertebrates remains contentious. This may be due to the fact that most studies of vertebrates have focused on facultative adjustment in relation to maternal condition, rather than processes that might produce uniform sex biases across individuals. Here, we examine the effects of local resource enhancement (LRE) and local resource competition (LRC) on birth sex ratios (BSRs). We also examine the effects of sex differences in the costs of rearing male and female offspring on BSRs. We present data from 102 primate species and show that BSRs are skewed in favour of the dispersing sex in species that do not breed cooperatively, as predicted by the LRC model. In accordance with the LRE model, BSRs are generally skewed in favour of the more beneficial sex in cooperatively breeding primate species. There is no evidence that BSRs reflect the extent of sexual size dimorphism, an indirect measure of the costs of rearing male and female offspring. These analyses suggest that adaptive processes may play an important role in the evolution of BSRs in vertebrates.

Lessons from animal teaching

Many species are known to acquire valuable life skills and information from others, but until recently it was widely believed that animals did not actively facilitate learning in others. Teaching was regarded as a uniquely human faculty. However, recent studies suggest that teaching might be more common in animals than previously thought. Teaching is present in bees, ants, babblers, meerkats and other carnivores but is absent in chimpanzees, a bizarre taxonomic distribution that makes sense if teaching is treated as a form of altruism. Drawing on both mechanistic and functional arguments, we integrate teaching with the broader field of animal social learning, and show how this aids understanding of how and why teaching evolved, and the diversity of teaching mechanisms.

Toxicity and characterization of cotton expressing Bacillus thuringiensis Cry1Ac and Cry2Ab2 proteins for control of lepidopteran pests

Cry1Ac protoxin (the active insecticidal toxin in both Bollgard and Bollgard II cotton [Gossypium hirsutum L.]), and Cry2Ab2 toxin (the second insecticidal toxin in Bollgard II cotton) were bioassayed against five of the primary lepidopteran pests of cotton by using diet incorporation. Cry1Ac was the most toxic to Heliothis virescens (F.) and Pectinophora gossypiella (Saunders), demonstrated good activity against Helicoverpa zea (Boddie), and had negligible toxicity against Spodoptera exigua (Hübner) and Spodoptera frugiperda (J. E. Smith). Cry2Ab2 was the most toxic to P. gossypiella and least toxic to S. frugiperda. Cry2Ab2 was more toxic to S. exigua and S. frugiperda than Cry1Ac. Of the three insect species most sensitive to both Bacillus thuringiensis (Bt) proteins (including H. zea), P. gossypiella was only three-fold less sensitive to Cry2Ab2 than Cry1Ac, whereas H. virescens was 40-fold less sensitive to Cry2Ab2 compared with CrylAc. Cotton plants expressing Cry1Ac only and both Cry1Ac and Cry2Ab2 proteins were characterized for toxicity against H. zea and S.frugiperda larvae in the laboratory and H. zea larvae in an environmental chamber. In no-choice assays on excised squares from plants of different ages, second instar H. zea larvae were controlled by Cry1Ac/Cry2Ab2 cotton with mortality levels of 90% and greater at 5 d compared with 30-80% mortality for Cry1Ac-only cotton, depending on plant age. Similarly, feeding on leaf discs from Cry1Ac/Cry2Ab2 cotton resulted in mortality of second instars of S.frugiperda ranging from 69 to 93%, whereas exposure to Cry1Ac-only cotton yielded 20-69% mortality, depending on plant age. When cotton blooms were infested in situ in an environmental chamber with neonate H. zea larvae previously fed on synthetic diet for 0, 24, or 48 h, 7-d flower abortion levels for Cry1Ac-only cotton were 15, 41, and 63%, respectively, whereas for Cry1Ac/Cry2Ab2 cotton, flower abortion levels were 0, 0, and 5%, respectively. Cry1Ac and Cry2Ab2 concentrations were measured within various cotton tissues of Cry1Ac-only and Cry1Ac/Cry2Ab2 plants, respectively, by using enzyme-linked immunosorbent assay. Terminal leaves significantly expressed the highest, and large leaves, calyx, and bracts expressed significantly the lowest concentrations of Cry1Ac, respectively. Ovules expressed significantly the highest, and terminal leaves, large leaves, bracts, and calyx expressed significantly (P < 0.05) the lowest concentrations of Cry2Ab2. These results help explain the observed differences between Bollgard and Bollgard II mortality against the primary lepidopteran cotton pests, and they may lead to improved scouting and resistance management practices, and to more effective control of these pests with Bt transgenic crops in the future.

Toxicity and characterization of cotton expressing Bacillus thuringiensis Cry1Ac and Cry2Ab2 proteins for control of lepidopteran pests

Cry1Ac protoxin (the active insecticidal toxin in both Bollgard and Bollgard II cotton [Gossypium hirsutum L.]), and Cry2Ab2 toxin (the second insecticidal toxin in Bollgard II cotton) were bioassayed against five of the primary lepidopteran pests of cotton by using diet incorporation. Cry1Ac was the most toxic to Heliothis virescens (F.) and Pectinophora gossypiella (Saunders), demonstrated good activity against Helicoverpa zea (Boddie), and had negligible toxicity against Spodoptera exigua (Hübner) and Spodoptera frugiperda (J. E. Smith). Cry2Ab2 was the most toxic to P. gossypiella and least toxic to S. frugiperda. Cry2Ab2 was more toxic to S. exigua and S. frugiperda than Cry1Ac. Of the three insect species most sensitive to both Bacillus thuringiensis (Bt) proteins (including H. zea), P. gossypiella was only three-fold less sensitive to Cry2Ab2 than Cry1Ac, whereas H. virescens was 40-fold less sensitive to Cry2Ab2 compared with CrylAc. Cotton plants expressing Cry1Ac only and both Cry1Ac and Cry2Ab2 proteins were characterized for toxicity against H. zea and S.frugiperda larvae in the laboratory and H. zea larvae in an environmental chamber. In no-choice assays on excised squares from plants of different ages, second instar H. zea larvae were controlled by Cry1Ac/Cry2Ab2 cotton with mortality levels of 90% and greater at 5 d compared with 30-80% mortality for Cry1Ac-only cotton, depending on plant age. Similarly, feeding on leaf discs from Cry1Ac/Cry2Ab2 cotton resulted in mortality of second instars of S.frugiperda ranging from 69 to 93%, whereas exposure to Cry1Ac-only cotton yielded 20-69% mortality, depending on plant age. When cotton blooms were infested in situ in an environmental chamber with neonate H. zea larvae previously fed on synthetic diet for 0, 24, or 48 h, 7-d flower abortion levels for Cry1Ac-only cotton were 15, 41, and 63%, respectively, whereas for Cry1Ac/Cry2Ab2 cotton, flower abortion levels were 0, 0, and 5%, respectively. Cry1Ac and Cry2Ab2 concentrations were measured within various cotton tissues of Cry1Ac-only and Cry1Ac/Cry2Ab2 plants, respectively, by using enzyme-linked immunosorbent assay. Terminal leaves significantly expressed the highest, and large leaves, calyx, and bracts expressed significantly the lowest concentrations of Cry1Ac, respectively. Ovules expressed significantly the highest, and terminal leaves, large leaves, bracts, and calyx expressed significantly (P < 0.05) the lowest concentrations of Cry2Ab2. These results help explain the observed differences between Bollgard and Bollgard II mortality against the primary lepidopteran cotton pests, and they may lead to improved scouting and resistance management practices, and to more effective control of these pests with Bt transgenic crops in the future.

Suppression of prolactin does not reduce infant care by parentally experienced male common marmosets (Callithrix jacchus)

High levels of prolactin have been found to correlate with the expression of paternal care in a variety of taxa. However, in mammals, there is little experimental evidence that prolactin is causally involved in the stimulation or maintenance of paternal care. Here, we suppressed prolactin production in paternally experienced common marmoset fathers in their family groups during the first 2 weeks after their infants were born. Circulating prolactin levels were suppressed using cabergoline (Dostinex: Pfizer), a long acting dopamine (D2) agonist with minimal behavioural side-effects. A within-subject design was used to compare behavioural and hormonal data on 5 paternally experienced fathers during two consecutive births. Cabergoline reduced prolactin to negligible levels in all fathers without effecting testosterone, DHT and cortisol and without adverse side-effects. However, lowering prolactin had no significant effect on the expression of majority of the behaviour patterns associated with paternal care. These included infant carrying, infant grooming and the frequency with which fathers retrieved and rejected infants. The only infant-related behaviour to be affected was the frequency with which fathers touched, licked and investigated infants. We noted a marginally significant increase in this behaviour during cabergoline treatment. Despite the lack of effect on paternal care, cabergoline did exert an effect on the affiliative/sexual behaviour of fathers as there was a significant increase in the grooming behaviour fathers directed at and received from their mates during drug treatment. This study showed that experienced male marmosets can express paternal behaviour in the absence of the high prolactin levels normally seen after infants are born.

Sexual selection: copycat mating in birds

Female zebra finches may be influenced by the choices of other females when selecting mates, challenging the view that mate-choice copying should not occur in species with biparental care.

Maternal rank and local resource competition do not predict birth sex ratios in wild baboons

We test two models of adaptive adjustment of birth sex ratios that are expected to apply to Cercopithecine primate species. It has been predicted that when maternal investment differentially influences the reproductive success of male and female offspring, females in good condition will bias investment in favour of the sex that gains the greatest fitness returns from additional investment. This hypothesis was subsequently amended to take into account the effects of local resource competition on maternal investment strategies of primate females. This body of theory has been applied to primates with contradictory results, prompting some to question the conclusion that primate females facultatively adjust birth sex ratios in an adaptive manner. Here, we present a meta-analysis of the relationship between maternal rank, birth sex ratios and local resource competition in 36 groups of wild savannah baboons, Papio cynocephalus. The results do not support predictions derived from either model of facultative sex ratio adjustment, and we conclude that there is currently no evidence that baboon birth sex ratios are adjusted in an adaptive manner.

Adult-infant food transfer in common marmosets: an experimental study

Infant marmosets and tamarins obtain solid food items from adults during and after the time of weaning. In addition to providing nutrients, food transfers may provide infants with the opportunity to learn about diet. The aim of this study was to investigate patterns of begging and food transfer in captive groups of common marmosets during tests with 1) palatable novel food, 2) unpalatable novel food, and 3) familiar food. Infants may gain an opportunity to learn about diet breadth by preferentially begging for novel rather than familiar items, while adults may facilitate infant learning by differing in their willingness to transfer food depending upon the food's novelty or palatability. In this study, infants exhibited more interest and begging with novel food items than with familiar ones. However, food transfers were not more likely to occur with novel foods than with familiar ones, and in fact adults were more likely to refuse infant begging attempts with novel foods. The palatability of the food also did not influence the rates of refusal and transfer: adults transferred palatable and unpalatable novel foods with similar frequencies. These results suggest that infant marmosets gain an opportunity to learn about diet breadth by begging for novel foods, but adults do not preferentially transfer novel or palatable food items.

Combination therapy for the treatment of hepatitis C in the veteran population: higher than expected rates of therapy discontinuation

AIM

To compare the efficacy of high-dose induction with standard dose interferon therapy for the treatment of chronic hepatitis C virus at the Dallas Veterans Affairs Medical Center.

METHODS

Patients were randomized to receive 5 million units daily interferon-alpha2b for 4-weeks followed by 44-weeks for genotype 1 or 20 weeks for non-genotype 1 of standard dose therapy (3 million units three times a week) or standard dose therapy for total treatment duration. Daily weight-based ribavirin was used for entire therapy interval.

RESULTS

Forty-five patients were enrolled in the trial with genotype 1 comprising 75.6% of the sample. Cirrhosis or bridging-fibrosis was present in 69% of the patients. Of the 29 liver biopsies available for Knodell scoring, 41% and 51% had scores of 6-10 and 11-15, respectively. Rates of sustained virological response did not differ significantly between the two treatment groups. Therapy type and/or early intervention for depression did not affect the rate of therapy discontinuation, which was 26.6%.

CONCLUSION

The rate of sustained virological response was similar between the two treatment groups and higher than anticipated among patients with cirrhosis or bridging-fibrosis. The rate of therapy discontinuation was also higher than anticipated but was not attributable to therapy type or untreated depression.

Comparing EST-based genetic maps between Pinus sylvestris and Pinus taeda

A genetic map of Pinus sylvestris was constructed using ESTP (expressed sequence tag polymorphism) markers and other gene-based markers, AFLP markers and microsatellites. Part of the ESTP markers (40) were developed and mapped earlier in Pinus taeda, and additional markers were generated based on P. sylvestris sequences or sequences from other pine species. The mapping in P. sylvestris was based on 94 F(1) progeny from a cross between plus-tree parents E635C and E1101. AFLP framework maps for the parent trees were first constructed. The ESTP and other gene sequence-based markers were added to the framework maps, as well as five published microsatellite loci. The separate maps were then integrated with the aid of AFLPs segregating in both trees (dominant segregation ratios 3:1) as well as gene markers and microsatellites segregating in both parent trees (segregation ratios 1:1:1:1 or 1:2:1). The integrated map consisted of 12 groups corresponding to the P. taeda linkage groups, and additionally three and six smaller groups for E1101 and E635C, respectively. The number of framework AFLP markers in the integrated map is altogether 194 and the number of gene markers 61. The total length of the integrated map was 1,314 cM. The set of markers developed for P. sylvestris was also added to existing maps of two P. taeda pedigrees. Starting with a mapped marker from one pedigree in the source species resulted in a mapped marker in a pedigree of the other species in more than 40% of the cases, with about equal success in both directions. The maps of the two species are largely colinear, even if the species have diverged more than 70 MYA. Most cases of different locations were probably due to problems in identifying the orthologous members of gene families. These data provide a first ESTP-containing map of P. sylvestris, which can also be used for comparing this species to additional species mapped with the same markers.

Reconsidering the null hypothesis: Is maternal rank associated with birth sex ratios in primate groups?

Trivers and Willard hypothesized that vertebrates adaptively vary the sex ratio of their offspring in response to the mother's physical condition [Trivers, R. L. & Willard, D. (1973) Science 179, 90-92]. This hypothesis has produced considerable debate within evolutionary biology. Here we use meta-analysis techniques to evaluate claims that nonhuman primate females facultatively adjust the sex ratio of their progeny in relation to their own dominance rank in a uniform way. The magnitude of the difference in birth sex ratios of high- and low-ranking females declines as sample sizes increase, and the mean difference in birth sex ratios of high- and low-ranking females is zero. These results suggest that the observed effects could be the product of stochastic variation in small samples. These findings indicate that presently we cannot reject the null hypothesis that maternal dominance rank is unrelated to birth sex ratios.

Potassium uptake and retention by Oceanomonas baumannii at low water activity in the presence of phenol

Oceanomonas baumannii(T) (ATCC 700832) is a halotolerant bacterium capable of degrading phenol, which requires potassium in order for turgor growth to occur in minimal medium containing 5% NaCl (w/v). However, at this salinity growth can be inhibited by reduced potassium concentrations. The affinity for potassium (K(S)) was determined to be 219 microM and 408 microM for cultures utilising phenol and succinate respectively as the sole carbon source for growth. Rubidium but not caesium could substitute for potassium in alleviating growth inhibition due to potassium limitation. The effect of elevated phenol on potassium retention was studied, and it was shown that contrary to expectations, as external phenol concentration was increased the levels of intracellular potassium were significantly elevated. This observation correlated with changes in the cytoplasmic membrane, particularly the increase in the saturated:unsaturated fatty acid ratio from 0.47 to 1.44, and the decrease in the zwitterionic:anionic phospholipid ratio from 2.23 to 1.22. Both these changes promote membrane bilayer configurations and increase lipid ordering of the membrane reducing its permeability and inhibiting cation efflux.

Anchored reference loci in loblolly pine (Pinus taeda L.) for integrating pine genomics

Anchored reference loci provide a framework for comparative mapping. They are landmarks to denote conserved chromosomal segments, allowing the synthesis of genetic maps from multiple sources. We evaluated 90 expressed sequence tag polymorphisms (ESTPs) from loblolly pine (Pinus taeda L.) for this function. Primer sets were assayed for amplification and polymorphism in six pedigrees, representing two subgenera of Pinus and a distant member of the Pinaceae, Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). On average, 89% of primer sets amplified in four species of subgenus Pinus, 49% in one species of subgenus Strobus, and 22% in Douglas-fir. Polymorphisms were detected for 37-61% of the ESTPs within each pedigree. Comparative mapping in loblolly and slash pine (P. elliottii Englm.) revealed that ESTPs mapped to the same location. Disrupted synteny or significant disruptions in colinearity were not detected. Thirty-five ESTPs met criteria established for anchor loci. The majority of those that did not meet these criteria were excluded when map location was known in only a single species. Anchor loci provide a unifying tool for the community, facilitating the creation of a "generic" pine map and serving as a foundation for studies on genome organization and evolution.

Novel 4-piperidinopyridine inhibitors of oxidosqualene cyclase-lanosterol synthase derived by consideration of inhibitor pK(a)

Potent inhibition of rat microsomal oxidosqualene cyclase-lanosterol synthase (OSC) was maintained after structural modification of the 4-piperidinopyridine OSC inhibitor series. These novel analogues with a much lower pK(a) range (5.8-6.7) gave potent oral inhibition of rat cholesterol biosynthesis (8 ED(80) 0.7 mg/kg), and diminished effects on rat feeding after a 100 mg/kg oral dose.

Virally infected hepatocytes are resistant to perforin-dependent CTL effector mechanisms

Cell-mediated cytotoxicity plays an important role in the clearance of noncytopathic viruses from infected tissues. Perforin-dependent cytotoxic mechanisms have been noted to play an important role in the clearance of infections from multiple extrahepatic organs. In contrast, mice with defects in the Fas/Fas ligand (FasL)-mediated cytotoxicity pathway exhibit delayed clearance of adenovirus from the liver without apparent delay in the clearance of viral infections from extrahepatic organs. The present studies examined the role of cytotoxic effector mechanisms in intrahepatic immune responses to a replication-defective, recombinant beta-galactosidase-encoding adenovirus (AdCMV-lacZ). Delayed clearance of AdCMV-lacZ from the livers of FasL-defective B6.gld mice, but not perforin-deficient B6.pfp(-/-) mice, was noted despite no significant differences in initial hepatic CD8(+) T cell IFN-gamma or TNF responses or in activation of intrahepatic cytotoxic lymphocytes cells capable of killing AdCMV-lacZ-infected fibroblast targets. In contrast, AdCMV-lacZ-infected hepatocyte targets were far more sensitive to killing by intrahepatic cytotoxic lymphocytes from B6.pfp(-/-) than from B6.gld mice, and residual levels of virus-specific killing of hepatocyte targets by FasL-defective B6.gld CTL were blocked by TNF inhibition. These results suggest that inherent resistance of hepatocytes to cytotoxicity mediated by perforin-dependent mechanisms leaves Fas/FasL-dependent, cell-mediated cytotoxicity as the major pathway for CTL-mediated killing of virally infected hepatocytes and accounts for the more prominent role of perforin-independent anti-viral mechanisms in immune responses in the liver.

Using proximity measures to describe mother-infant relationships

What are the relative roles of mothers and infants in maintaining proximity with one another? How do the relative roles of the mother and infant change over time? What do proximity measures tell us about the mother-infant relationship? Questions such as these have been addressed using proximity indices devised by Hinde and coworkers in the 1960s. In this paper, I review how these indices are derived and discuss what they do, and do not, infer about the nature of the mother-infant relationship. An additional index is proposed which indicates whether the mother or the infant is responsible for the majority of changes in proximity.

Reclassification of [Pseudomonas] doudoroffii (Baumann et al. 1983) into the genus Oceanomonas gen. nov. as Oceanomonas doudoroffii comb. nov., and description of a phenol-degrading bacterium from estuarine water as Oceanomonas baumannii sp. nov

A bacterium, isolate GB6T, capable of degrading phenol in the presence of elevated salinity was isolated from the estuary of the River Wear, UK. The bacterium was subjected to biochemical and molecular analysis to determine its taxonomic status. These studies indicated that the bacterium was a distinct species closely related to [Pseudomonas] doudoroffii. However, the phylogenetic analysis indicated that [Pseudomonas] doudoroffii was misclassified, as noted previously. Analysis of the characteristics of isolate GB6T and the type strain of [Pseudomonas] doudoroffii confirmed that these bacteria belonged to the same novel genus, which we have named Oceanomonas gen. nov. The type strain of Oceanomonas doudoroffii (Baumann et al. 1983) comb. nov. is ATCC 27123T (= DSM 7028T. The DNA-DNA homology between isolate GB6T and [Pseudomonas] doudoroffii is low and phenotypic differences between the two organisms are evident. Isolate GB6T (= ATCC 700832T = NCIMB 13685T) is therefore proposed as the type strain of a new species, Oceanomonas baumannii sp. nov.

A novel series of 4-piperidinopyridine and 4-piperidinopyrimidine inhibitors of 2,3-oxidosqualene cyclase-lanosterol synthase

A novel series of 4-piperidinopyridines and 4-piperidinopyrimidines showed potent and selective inhibition of rat 2,3-oxidosqualene cyclase-lanosterol synthase (OSC) (e.g. 26 IC(50) rat = 398 +/- 25 nM, human = 112 +/- 25 nM) and gave selective oral inhibition of rat cholesterol biosynthesis (26 ED(80) = 1.2 +/- 0.3 mg/kg, n = 5; HMGCoA reductase inhibitor simvastatin ED(80) = 1.2 +/- 0.3 mg/kg, n = 5). The piperidinopyrimidine OSC inhibitors have a significantly lower pK(a) than the corresponding pyridine or the previously reported quinuclidine OSC inhibitor series. This indicates that other novel OSC inhibitors may be found in analogues of this series across a broader pK(a) range (6.0-9.0). These series may yield novel hypocholesterolemic agents for the treatment of cardiovascular disease.

Bile Salt Anion Sorption by Polymeric Resins: Comparison of a Functionalized Polyacrylamide Resin with Cholestyramine

Cholestyramine and a cross-linked polyacrylamide resin with lateral alkyl quaternary ammonium groups (QPDA12) were used to study their ability to bind several bile salt anions (including the cholate, glycocholate, taurocholate, and chenodeoxycholate), individually and competitively, from phosphate buffer solutions at room temperature. The latter resin showed high affinities for all the bile salt anions examined, while cholestyramine exhibited a high affinity only for the more hydrophobic chenodeoxycholate. However, for the binding with cholestyramine, cooperative effects were more pronounced, leading to the enhancement of sorption at higher concentrations. The Langmuir equation and its modified versions were used in the interpretation of both individual and competitive binding of bile salts. The data from competitive binding studies indicated that the presence of the tightly bound chenodeoxycholate did not significantly diminish the ability of QPDA12 resin to bind cholate. However, for cholestyramine, the sorption of chenodeoxycholate increased the relative binding affinity for the more hydrophilic cholate, revealing a novel "cooperative" effect involving different bile salt anions. The latter results suggest that the observed higher affinity of QPDA12 is brought about predominantly through the hydrophobic interactions with the pendant alkyl groups rather than with the resin backbone. Copyright 2000 Academic Press.

Enhancement of MHC class I-stimulated alloresponses by TNF/TNF receptor (TNFR)1 interactions and of MHC class II-stimulated alloresponses by TNF/TNFR2 interactions

In vivo TNF inhibition has been observed to ameliorate the disease process attributed to T cell-dependent immune responses such as those generated during graft-vs.-host disease. The present studies were designed to evaluate whether TNF/TNF receptor (TNFR)1 and TNF/TNFR2 interactions were involved in the generation of allospecific T cell responses. Splenic lymphocyte populations were obtained from TNFR1- or TNFR2-deficient B6 mice and from control B6 mice. These responder cells were cultured with irradiated MHC class II-disparate B6.C-H-2bm12 (bm12) or MHC class I-disparate B6.C-H-2bm1 (bm1) or irradiated syngeneic stimulator cells for 3 days before assay of [3H]thymidine incorporation. IL-2 levels of the mixed lymphocyte culture (MLC) supernatants were assessed by enzyme-linked immunosorbent assay. With MHC class II-disparate bm12 stimulator cells, a significant reduction in T cell proliferation was observed utilizing TNFR2-deficient CD4+ responder T cells, but not when using TNFR1 -deficient CD4+ responder T cells. A significant decrease in proliferation of TNFR1-deficient CD8+ responder cells, but not of TNFR2-deficient CD8 responder T cells was observed after stimulation with MHC class I-disparate bm1 stimulator cells. IL-2 levels were lower in MLC utilizing MHC class I stimulators and TNFR1-deficient responders or MHC class II stimulators and TNFR2-deficient responders. These results indicate that TNF/TNFR2 interactions promote MHC class II-stimulated alloresponses, while TNF/TNFR1 interactions promote MHC class I-stimulated alloresponses.