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3 Schematic drawing of some of the subcellular organelles found in eucaryotic cells. The genetic material (large strands of DNA coiled into chromosomes) is sequestered within the nucleus of the cell (depicted as fibers within the nucleus). Protein synthesis occurs on the ribosomes in the rough endoplasmic reticulum. Additional processing takes place in the Golgi apparatus where proteins that were synthesized for export are sequestered in secretory vesicles. Mitochondria provide energy for cellular metabolism.
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[Conveys] the excitement of a field that has embraced the perspectives and contributions of diverse lines of research [in attempting to understand the interactions between hormones and behavior].
[Gives] due credit to those scientists who laid the foundations of the field by presenting current ideas, hypotheses, and theories within the context of...
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Objective
The objective of this article is to critically assess the value of a medical student and junior doctor weekend introduction to urology course.
Materials and methods
All UK medical students and foundation doctors were invited to attend an introductory course held at The Royal Society of Medicine, London, organised by the Section of Urolog...
Citations
... Studying how these affects occur and their outcomes can provide important insight into the mechanisms and evolution of behaviour. Hormones do not cause behavioural changes directly, but affect the likelihood of a specific behaviour occurring in the presence of the appropriate stimuli in the appropriate context (Nelson and Kriegsfeld, 2017;Gruchalla Russart and Nelson, 2019). While hormones affect behaviour, behaviour and external stimuli can also feed back and affect hormone concentrations. ...
... The extent to which behaviour is mediated by hormones differs among species. While sexual behaviour in rodents is highly dependent on hormones, in primates, sexual behaviour is less dependent on hormones and more on social interactions and learning (Nelson and Kriegsfeld, 2017;Bakker, 2019). Both environmental factors and social cues can influence hormone-behaviour interactions (e.g., time of day, perceived food availability, social interactions, population density, presence of females; Wilsterman et al., 2019). ...
... Androgens (i.e., male sex hormones), such as testosterone, play an important role in the stimulation of spermatogenesis, the development of primary and secondary sex characters and the mediation of reproductive behaviours (Slater, 1978;Nelson and Kriegsfeld, 2017). ...
How the underlying forces of sexual selection impact reproductive tactics including elaborate acoustic displays in cetaceans remains poorly understood. Here, I combined 26 years (1995-2020) of photo-identification, behavioural, (epi)genetic, and endocrine data from an endangered population of humpback whales (New Caledonia), to explore male reproductive success, age, physiology, and population dynamics over almost a third of the lifespan of a humpback whale. First, I conducted a paternity analysis on 177 known mother-offspring pairs and confirmed previous findings of low variation in reproductive success in male humpback whales. Second, epigenetic age estimates of 485 males revealed a left-skewed population age structure in the first half of the study period that became more balanced in the second half. Further, older males (> 23 years) more often engaged in certain reproductive tactics (singing and escorting) and were more successful in siring offspring once the population age structure stabilised, suggesting reproductive tactics and reproductive success in male humpback whales may be age-dependent. Third, using enzyme immunoassays on 457 blubber samples, I observed a seasonal decline in male testosterone in the population over the breeding season. Testosterone levels appeared highest during puberty, then decreased and levelled off at the onset of maturity, yet were highly variable at any point during the breeding season and across males of all ages. Lastly, I investigated the influence of genetic diversity at the major histocompatibility complex (MHC) class I and class IIa (DQB and DRB-a) on patterns of male reproductive success in humpback whales. Mating pairs shared fewer alleles than expected under random mating at MHC class I and IIa, thus, providing evidence of an MHC-mediated female mate choice in humpback whales. This thesis provides novel, critical insights into the evolutionary consequences of commercial whaling on the demography, patterns of reproduction and sexual selection of exploited populations of baleen whales.
... Animal personality is typically measured along five main axes: aggressive-docile, exploration affine-averse, sociable-solitary, bold-shy and active-passive (Réale et al., 2007). Several behaviors across these five axes are known to be modulated by sex steroids, precisely androgens and especially during the reproductive season (Hau, 2007;Nelson, 2005). In male vertebrates, androgens play a key role in the development and maintenance of primary and secondary sexual traits but also regarding the modulation of different behaviors related to reproduction, such as courtship, mating behavior or territorial aggression (Burmeister and Wilczynski, 2001;Fusani, 2008;Hirschenhauser et al., 2003;Hunt et al., 2019;Rosvall et al., 2020;Rosvall et al., 2012). ...
... This was contrary to what we expected, as in a previous study androgen levels were found to be increased in the afternoon compared to morning hours, which was linked to general calling activity in a nearby A. femoralis population . In vertebrates, steroid concentrations commonly undergo a circadian rhythm; they increase during early morning hours and drop in the afternoon (Nelson, 2005). Several studies have documented the existence of diurnal cycles of circulating T (fish: Lorenzi et al., 2008;monkeys: Schlatt et al., 2008;humans: Diver et al., 2003; but see also Licht et al., 1985 for green sea turtles). ...
... Circadian clocks organize behavior and physiology to adapt to daily environmental cycles, and all biological traits, including hormone level, exhibit daily rhythms (Allada & Chung, 2010). Hormonal circadian rhythms have been studied extensively in humans and other vertebrates, but much less in insects (Nelson, 1995;Bloch et al., 2013;Zera et al., 2017). Several studies have revealed that JH titer displays a circadian rhythm in insects (Ramaswamy et al., 2000;Elekonich et al., 2001;Zhao & Zera, 2004;Zera et al., 2007). ...
The cricket Velarifictorus aspersus (Walker) (Orthoptera: Gryllidae) exhibits a wing dimorphism
mediating two distinct life-history
strategies during early adulthood; long-winged
(LW) females mainly invest resources in flight, whereas short-winged
(SW)
females invest more heavily in reproduction than LW females. To understand the relationships
among juvenile hormone (JH), flight capacity, and energy accumulation,
the daily rhythm of JH titer and flight activity, the concentrations of flight energy substances,
and the influence of exogenous JH on flight activity and flight energy substances
were investigated in V. aspersus. The results showed that the hemolymph JH
titer exhibited a high-amplitude
daily rhythm in 5-day-
old
LW V. aspersus females, and
the JH titer rose about 10× at 18:00 hours (6 h before lights off) and dropped to baseline
levels after lights off. The females flew inactively (i.e., they floated in the air) from
14:00 to 19:00 hours during the light period, whereas they had a stronger flight capacity
in the initial photophase and before lights out. The flight ability of LW females with
20 μg μL−1 JH treatments was significantly improved during periods of flight inactivity.
After the peak JH titer, the concentrations of glycogen and trehalose in the flight muscles
increased significantly. The LW females treated with JH during the inactive flight
period had a significant increase in glycogen after 1 h and trehalose after 3 h. These
results suggested that the high-amplitude
daily rhythm of the JH titer was correlated
with accumulation of flight energy substance and flight capacity; that is, an elevated
JH titer promoted the biosynthesis of flight energy substances, resulting in improvement
of flight capacity.
... This information complements the increased PCVs seen in hawksbills versus greens in this study that may also be related to increasing diving activity (Stamper et al., 2005;Perrault et al., 2016;Stacy et al., 2018). Additionally, blood levels of lactate and corticosterone should also be incorporated into future studies as they play an integral role in anaerobic glycolysis and have been shown to correlate with blood GLU levels in hatchlings during both their crawling and swimming activity (Munck and Koritz, 1962;Nelson, 2005;Hamann et al., 2006;Neave, 2008;Pereira et al., 2013). Hyperkalemia has been noted with certain capture methods, such as trawling, because during this process animals are briefly submerged (Stabenau et al., 1991;Stabenau and Vietti, 2003;Perrault et al., 2020). ...
Historically, juvenile and subadult green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles have been observed in the waters surrounding St. Kitts, West Indies yearround; however, no formal population or health assessment for these species and cohorts in St. Kitts has been previously conducted. During the study period (2004–2017), 211 juvenile sea turtles (158 hawksbills, 53 greens) were captured at sixteen different capture sites in St. Kitts. Once on shore and restrained, morphometric measurements and mass were collected, untagged animals were tagged, and a health assessment was performed. Blood samples were collected and used to establish reference intervals for hematological and biochemical parameters. These reported reference intervals make it possible to incorporate monitoring programs for infectious diseases and to identify any trends in population and health status. The morphometrics, mass, and number of animals captured enable sound decision making as it relates to conservation policy development and implementation which is especially important in countries such as St. Kitts and Nevis where an open harvest for sea turtles still exists.
... Endogenous and environmental factors (also known as zeitgeber) entrain the behavior of vertebrates to the 24-hour or 12-month period [70]. Melatonin is one of the important timekeeping hormones in vertebrates [71] and its production is sensitive to light [72]. ...
The Panamanian golden frog (Atelopus zeteki) is a critically endangered species and currently is believed to survive and reproduce only in human care. Panamanian golden frog males are considerably vocal which may be an important component in their successful reproduction, though little is currently known about their calls. To better understand the behavior and vocal patterns of this species and to improve breeding efforts in the assurance colony, we employed individual sound recording of male advertisement calls and acoustic monitoring of a breeding colony to investigate variation in the vocal behavior of Panamanian golden frogs. The goal was to capture variability within and among frogs as well as patterns of periodicity over time. First, the advertisement calls from individual male Panamanian golden frogs were recorded, and acoustic parameters were analyzed for individual differences. Results suggest that male advertisement calls demonstrate individual- and population specificity. Second, data collected through a year-long acoustic monitoring of the breeding colony were investigated for circadian and circannual periodicity. Male vocal activity revealed a circadian periodicity entrained by the daily light schedule. Seasonal periodicity was also found with highest vocal activities between December and March. The finding of a seasonal periodicity is worth noting given that the population had been bred for 20 years under constant environmental conditions. Finally, results suggest that vocal activity was responsive to daily animal care activity. Vocal activity decreased substantially when personnel entered the room and engaged in animal husbandry activities. The findings illustrate the usefulness of acoustic monitoring to provide insight into animal behavior in a zoo setting in a key breeding colony of endangered animals, and calling pattern observations may be utilized to modify husbandry practices to improve Panamanian golden frog breeding success and general care.
... To assess reproductive physiology, we measured GnRH-induced testosterone ('max T'), cloacal protuberance volume ('CP volume'), sperm count, and deformed sperm proportion. Testosterone helps support vertebrate spermatogenesis and reproductive behavior 42 . For example, max T reflects the circulating level of testosterone produced in male juncos during aggressive intrasexual encounters 43 . ...
While Plasmodium parasitism is common in songbirds, its impact on avian reproduction is unclear owing to conflicting reports in the existing literature. Particularly understudied is the impact of phase of infection on variation in host reproductive physiology in wild, breeding-condition birds. However, assessing the full impact of Plasmodium on reproductive success in the wild can be difficult because individuals experiencing severe effects of parasitism may not enter the breeding population and may be less likely to be captured during field studies. To address these factors, we quantified metrics of health and reproductive physiology in wild-caught, breeding-condition male dark-eyed juncos (Junco hyemalis hyemalis) before and after experimental Plasmodium inoculation in a captive setting. Metrics of health and reproductive physiology included activity rate, hematocrit, scaled body mass, testosterone and sperm production. Individuals already infected at capture (i.e., chronically infected) had higher levels of hematocrit than males without chronic infections. Experimentally infected males showed a larger reduction in hematocrit and activity rate as compared to controls. However, chronic infection status did not influence the extent of metric decline. Testosterone production did not vary by treatment and most birds produced sperm following inoculation. Broadly, our results suggest that male juncos exposed to Plasmodium during the breeding season likely experience declines in general health, but Plasmodium infections do not negatively impact reproductive physiology. We conclude that physiological tradeoffs in males may favor maintenance of reproductive function despite infection.
... Chen et al. (2013) base their predictions on the medical and psychological literature and cite Richardson (1992), who claims that most menstruating women tend to "experience a variety of physical, psychological and behavioral changes during the period between ovulation and menstruation." Schipper (2014) bases predictions on a handbook of behavioral endocrinology (Nelson, 2011) and takes the MC as a proxy for hormonal fluctuation. Lazzaro et al. (2016) begin with a list of behaviors that are affected by the MC beyond those related to reproductive function and continue with brain-imaging studies, focusing on the reward centers that should imply changes in economic behavior. ...
... However, high level of cortisol is mediated by stimulation of the adrenal cortex which is regulated by the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system (SNS) (Matisz et al., 2021). Although stress is an important factor in the etiology of behavioral disorders, it also increases the availability of energy for motor activities by raising blood glucose levels (Nelson 2005) In this present study, oral intake of vitamin C (Ascorbic Acid) increased locomotor activities and also improved the exploratory activities in the rats. In 2020, Moritz et al. (2020) reported that ascorbic acid has neuroprotective effects whose mechanism of action is poorly understood. ...
Constant exposure to environmental stress has negative behavioral outcomes. Considering the inverse relationship between stress and Vitamin C intake, this study was aimed at investigating variable stress techniques and Vitamin C supplementation on exploratory/locomotor behaviors in male Wistar rats. Twenty-eight male Sprague-Dawley rats (100g-120g) were allotted into four groups (n=7). Control received 10ml/kg distilled water, group two received 100 mg/kg vitamin C, group three was exposed to different models of stress while group four was stressed alongside 100 mg/kg vitamin C. Vitamin C treatments were given orally for 2 weeks. Animals in groups 3 and 4 were stressed every other day with models such as multiple cage changes, exposure to noise, overnight strange objects, overnight wetting of beddings, and immobility. Explorative and locomotor activities were assessed with the open field test, novel object recognition test, and Y maze test using a Logitech camera and ANY-maze software to track the movement of the rats. Cortisol was assayed in the serum using Enzyme-linked Immuno Assay (ELISA) kit. Superoxide Dismutase, catalase, and lipid peroxidase; malondialdehyde (MDA) were also assayed in the serum. The results show that locomotor activities such as distance traveled, average speed, and time spent in the center square was significantly reduced by stress. These activities were improved with the intake of vitamin C compared with stress. Explorative activities such as locomoting around the environment, orientating towards novelty, and touching or sniffing novel objects were significantly increased in the rats on Vitamin C supplements and reduced in the stressed group. In the serum, cortisol level was significantly increased in rats exposed to stress and decreased with Vitamin C intake. Stress also significantly increased MDA and decreased SOD and CAT while vitamin C supplement decreased MDA and increased SOD and CAT. In conclusion, oral intake of vitamin C enhanced explorative/locomotor behavior and increased oxidative stress in rats exposed to different models of stress
... Glucocorticoids are a group of steroid hormones, the most prominent of which is cortisol in primates. In response to the individual's exposure to challenging circumstances, the hypothalamicpituitary-adrenal axis is activated, triggering the adrenal cortex to release glucocorticoids into the bloodstream (Sapolsky et al., 2000;Anestis, 2010;Nelson and Kriegsfeld, 2022). The action of glucocorticoids leads to changes in metabolism and cardiovascular activity that mobilize energy reserves and direct glucose, fatty acids and triglycerides to skeletal muscle and the brain, thereby helping the individual cope with emergency situations. ...
... Androgens are steroid hormones primarily secreted by the gonads, which include testosterone and its metabolites. They are responsible for the development of male genital organs and secondary sexual characters, and their protein anabolic action fosters muscle and bone strength (Dixson, 2012;Nelson and Kriegsfeld, 2022). Androgens play a prominent role in male reproductive effort by promoting sexual and aggressive behaviors in the context of mating, but these effects come at the cost of increased metabolic expenditureand thus food needsand depressed immune function (Wingfield et al., 2001;Muehlenbein and Bribiescas, 2005;Anestis, 2010). ...
... Hormones contribute to the adjustment of the organism to life history changes, so it is understandable that glucocorticoid and androgen secretion continues to vary with age in primates after puberty (Ostner et al., 2008a;Teichroeb and Sicotte, 2008;Beehner et al., 2009;Girard-Buttoz et al., 2009;Higham et al., 2013;Muller et al., 2021). These hormones can also exhibit pronounced variations over the course of a year or day (Nelson and Kriegsfeld, 2022). Both glucocorticoids and androgens can be affected by season or ambient temperature, even in non-seasonal breeders (Arlet et al., 2011;Gesquiere et al., 2011b;Tinsley Johnson et al., 2018;Christensen et al., 2022). ...
Glucocorticoid and androgen hormones play a prominent role in male reproductive effort. Their production usually increases in non-human primates during mating competition, which may include rivalry for access to receptive females, struggles for high dominance rank, or social pressure on low-ranking individuals. It is generally assumed that glucocorticoids and androgens are associated with mating challenges rather than dominance status, but the involvement of multiple factors makes it difficult to disentangle the two. In this regard, Tonkean macaques provide a suitable model because they are characterized by relaxed dominance and year-round breeding, meaning that there is typically no more than one receptive female in a group, and thus first-ranking males can easily monopolize her. We studied two captive groups of Tonkean macaques over an 80-month period, recording the reproductive status of females, collecting urine from males and sampling behaviors in both sexes. Male urinary hormone concentrations could be affected by increased competition caused by the mating period, the number of males and the degree of female attractiveness. The highest increases in androgens were recorded in males performing female mate-guarding. Despite the importance of dominance status in determining which males can mate, we found no significant effect of male rank on glucocorticoids and only a marginal effect on androgens during mate-guarding. Both types of hormones were more directly involved in the mating effort of males than in their dominance status. Our results show that their function can be understood in light of the particular competitive needs generated by the species-specific social system.
... VTA and GCT are primary sources of dopaminergic input to the song control system (63)(64)(65) and these projections have a well-established role in regulating birdsong (11,(66)(67)(68). Also, VTA neurons that project to the broader SDMN are critical for the expression of social motivation and reward (11,(69)(70)(71) and GCt neurons that project to the hindbrain control social behavior motor patters (72). And, the VTA and GCt of starlings also express DA receptors (3) and dopaminergic projections to these midbrain regions influence the expression of social behavior (including vocal communication) (73)(74)(75)(76). ...
Introduction
It has been proposed that in species that defend territories across multiple life history stages, brain metabolism of adrenal dehydroepiandrosterone (DHEA) regulates aggressive behavior at times when gonadal androgen synthesis is low (i.e. the non-breeding season). To date, a role for DHEA in the regulation of other forms of social behavior that are expressed outside of the context of breeding remains unknown.
Methods
In this experiment, we used the European starling ( Sturnus vulgaris ) model system to investigate a role for DHEA in the neuroendocrine regulation of singing behavior by males in non-breeding condition. Starling song in a non-breeding context is spontaneous, not directed towards conspecifics, and functions to maintain cohesion of overwintering flocks.
Results
Using within-subjects design, we found that DHEA implants significantly increase undirected singing behavior by non-breeding condition male starlings. Given that DHEA is known to modulate multiple neurotransmitter systems including dopamine (DA) and DA regulates undirected song, we subsequently used immunohistochemistry for phosphorylated tyrosine hydroxylase (pTH, the active form of the rate-limiting enzyme in DA synthesis) to investigate the effect of DHEA on dopaminergic regulation of singing behavior in a non-breeding context. Pearson correlation analysis revealed a positive linear association between undirected singing behavior and pTH immunoreactivity in the ventral tegmental area and midbrain central gray of DHEA-implanted, but not control-implanted, males.
Discussion
Taken together, these data suggest that undirected singing behavior by non-breeding starlings is modulated by effects of DHEA on dopaminergic neurotransmission. More broadly, these data expand the social behavior functions of DHEA beyond territorial aggression to include undirected, affiliative social communication.
