• Activation of southern white rhinoceros (Ceratotherium simum simum) estrogen receptors by phytoestrogens: Potential role in the reproductive failure of captive-born females?

      Tubbs, Christopher W.; Hartig, P.; Cardon, M.; Varga, Nicole; Milnes, Matthew R. (2012)
      The captive southern white rhinoceros (SWR; Ceratotherium simum simum) population serves as an important genetic reservoir critical to the conservation of this vulnerable species. Unfortunately, captive populations are declining due to the poor reproductive success of captive-born females....
    • Altered gonadal expression of TGF-beta superfamily signaling factors in environmental contaminant-exposed juvenile alligators

      Moore, B.C.; Milnes, Matthew R.; Kohno, S.; Katsu, Y.; Iguchi, T. (2011)
      Environmental contaminant exposure can influence gonadal steroid signaling milieus; however, little research has investigated the vulnerability of non-steroidal signaling pathways in the gonads. Here we use American alligators (Alligator mississippiensis) hatched from field-collected eggs to analyze gonadal mRNA transcript levels of the activin–inhibin–follistatin gene expression network and growth differentiation factor 9....
    • Cross-cultural consensus for waist–hip ratio and women's attractiveness

      Singh, Devendra; Dixson, B. J.; Jessop, T. S.; Morgan, Bethan J.; Dixson, Alan F.; (2010)
      In women of reproductive age, a gynoid body fat distribution as measured by the size of waist–hip ratio (WHR) is a reliable indicator of their sex hormone profile, greater success in pregnancy and less risk for major diseases. According to evolutionary mate selection theory, such indicators of health and fertility should be judged as attractive….
    • Effects of season and social interaction on fecal testosterone in wild male giant pandas: implications for energetics and mating strategies

      Nie, Y.; Zhang, Z.; Swaisgood, Ronald R.; Wei, F. (2012)
      In the first-ever study of reproductive endocrinology in wild male giant pandas (Ailuropoda melanoleuca), we provide new insights into the reproductive ecology of the species. We tracked and observed pandas in Foping Nature Reserve of the Qinling Mountains for 3 years, collecting fecal samples for testosterone metabolite analysis and data on reproductive activity....
    • Estrogenicity of captive southern white rhinoceros diets and their association with fertility

      Tubbs, Christopher W.; Moley, Laura A.; Ivy, Jamie A.; Metrione, Lara C.; LaClaire, Sydney; Felton, Rachel G.; Durrant, Barbara S.; Milnes, Matthew R. (2016)
      …In this study, we investigate the role of dietary phytoestrogens in this reproductive phenomenon by characterizing activation of southern white rhinoceros (SWR) estrogen receptors (ESRs) 1 and 2 by diet items from nine North American institutions and comparing female SWR fertility to total diet estrogenicity. Of the diet items tested, alfalfa hay and soy and alfalfa-based commercial pellets were found to be the most potent activators of SWR ESRs.…
    • Female giant panda (Ailuropoda melanoleuca) chirps advertise the caller's fertile phase

      Charlton, Benjamin D.; Keating, J. L.; Rengui, L.; Huang, Y.; Swaisgood, Ronald R.; (2010)
      Although female mammal vocal behaviour is known to advertise fertility, to date, no non-human mammal study has shown that the acoustic structure of female calls varies significantly around their fertile period. Here, we used a combination of hormone measurements and acoustic analyses to determine whether female giant panda chirps have the potential to signal the caller's precise oestrous stage (fertile versus pre-fertile)….
    • Giant pandas attend to androgen-related variation in male bleats

      Charlton, Benjamin D.; Swaisgood, Ronald R.; Zhihe, Zhang; Snyder, Rebecca J. (2012)
      Although androgen-dependant traits are predicted to signal overall male quality, no study has examined the response of a nonhuman animal to variation in a known acoustic cue to male androgen levels (steroid hormones that are key drivers of male sexual behaviour). Here, we use a single-speaker approach to present male and female giant pandas with re-synthesised male bleats representing callers with high and low androgen levels. Our results revealed that male and female giant pandas had significantly greater-looking responses, spent more time pacing, and were faster to respond to playbacks of bleats simulating high androgen males. When we analysed the sexes separately, a slightly different response pattern was revealed: whereas males and females still had significantly greater-looking responses and were faster to respond to bleats simulating high androgen males, only male giant pandas tended to spend more time pacing. These findings suggest that vocal cues to male androgen levels are functionally relevant to male and female giant pandas during the breeding season, and constitute the first demonstration that a nonhuman animal could be using a vocal signal to assess male hormonal state. We go on to discuss the ecological relevance of signalling androgen levels in this species’ sexual communication and the possible application of our results to conservation breeding.
    • Hormones and reproductive cycles in Crocodilians

      Milnes, Matthew R.; Norris, D.O.; Lopez, K.H. (ElsevierSan Diego, CA, 2011)
      During embryonic development, hormonal influence upon sexual differentiation in crocodilians begins and continues for years until sexual maturation is attained. Shortly after sex determination, estrogen production in the embryonic ovary increases and promotes proliferation of the Müsllerian ducts, whereas the testis produces anti-Müllerian hormone, which results in its regression....
    • Influences of sex, incubation temperature, and environmental quality on gonadal estrogen and androgen receptor messenger RNA expression in juvenile American alligators (Alligator mississippiensis)

      Moore, B.C.; Milnes, Mathew R.; Kohno, S.; Katsu, Y.; Iguchi, T.; LJ, Guilette, Jr; (2010)
      ...We have shown previously that gonads from wild-caught juvenile alligators express greater levels of estrogen receptor 1 (ESR1) than estrogen receptor 2 (ESR2).... These findings demonstrate that the mRNA expression of receptors required for steroid hormone signaling are modified by exposure to environmental factors, including temperature and contaminants.
    • Methods of estrus detection and correlates of the reproductive cycle in the sun bear (Helarctos malayanus)

      Frederick, Cheryl; Kyes, Randall; Hunt, Kathleen; Collins, Darin; Durrant, Barbara S.; Wasser, Samuel K.; (2010)
      The objective was to explore multiple methods for detecting and characterizing the reproductive cycle of the sun bear (Helarctos malayanus). Thirteen H. m. euryspilus females, loaned from the Malaysian government to US zoos, were used....
    • Relationship between behavioural diversity and faecal glucocorticoid metabolites: a case study with cheetahs (Acinonyx jubatus)

      Miller, Lance J.; Pisacane, CB; Vicino, Greg A. (2016)
      ... The goal of the current study was to continue efforts to validate behavioural diversity as an indicator of welfare using cheetah (Acinonyx jubatus) as a model species. Behavioural and faecal glucocorticoid metabolite data were collected on 18 cheetah at the San Diego Zoo Safari Park over a period of three months to explore the relationship between behavioural diversity and adrenal hormones related to the stress response.....
    • Reproductive competition and fecal testosterone in wild male giant pandas (Ailuropoda melanoleuca)

      Nie, Yonggang; Swaisgood, Ronald R.; Zhang, Zejun; Liu, Xiaobin; Wei, Fuwen (2012)
      ...Using global positioning system/very high frequency radiocollars to locate mating aggregations, we used behavioral observations and fecal testosterone assays to gain insight into male panda reproductive effort and strategies, and test theories relating to reproductive competition. Male pandas initially competed fiercely for access to females that were about to be fertile, but once male competitive status was determined, aggression rates declined....
    • Social context mediates testosterone's effect on snort acoustics in male hyrax songs

      Weissman, Yishai A.; Demartsev, Vlad; Ilany, Amiyaal; Barocas, Adi; Bar-Ziv, Einat; Geffen, Eli; Koren, Lee (2019)
      Testosterone affects physical and motivational states, both of which may strongly influence vocalization structure and acoustics. The loud complex calls (i.e., songs) of male rock hyraxes (Procavia capensis) are used as honest signals for advertising physical and social states. The snort, a low frequency, noisy element of the song, encodes information on the singer's age and social rank via harshness, as measured by jitter (i.e., acoustic frequency stability) and duration; suggesting that the snort concomitantly advertises both vocal stability and aggression. Our past findings revealed that testosterone levels are related to both vocal elements and social status of male hyraxes, suggesting that hormonal mechanisms mediate the motivation for aggressive and courtship behaviors. Here we examined whether long-term androgen levels are related to snort acoustics and song structure by comparing levels of testosterone in hair with acoustic and structural parameters. We found that songs performed by individuals with higher testosterone levels include more singing bouts and longer, smoother snorts, but only in those songs induced by external triggers. It is possible that hyraxes with higher levels of testosterone possess the ability to perform higher-quality singing, but only invest in situations of high social arousal and potential benefit. Surprisingly, in spontaneous songs, hyraxes with high testosterone were found to snort more harshly than low-testosterone males. The context dependent effects of high testosterone on snort acoustics suggest that the aggressive emotional arousal associated with testosterone is naturally reflected in the jittery hyrax snort, but that it can be masked by high-quality performance.
    • The acute phase protein ceruloplasmin as a non-invasive marker of pseudopregnancy, pregnancy, and pregnancy loss in the giant panda

      Willis, Erin L.; Kersey, David C.; Durrant, Barbara S.; Kouba, Andrew J. (2011)
      After ovulation, non-pregnant female giant pandas experience pseudopregnancy. During pseudopregnancy, non-pregnant females exhibit physiological and behavioral changes similar to pregnancy. Monitoring hormonal patterns that are usually different in pregnant mammals are not effective at determining pregnancy status in many animals that undergo pseudopregnancy, including the giant panda. Therefore, a physiological test to distinguish between pregnancy and pseudopregnancy in pandas has eluded scientists for decades. We examined other potential markers of pregnancy and found that activity of the acute phase protein ceruloplasmin increases in urine of giant pandas in response to pregnancy. Results indicate that in term pregnancies, levels of active urinary ceruloplasmin were elevated the first week of pregnancy and remain elevated until 20–24 days prior to parturition, while no increase was observed during the luteal phase in known pseudopregnancies. Active ceruloplasmin also increased during ultrasound-confirmed lost pregnancies; however, the pattern was different compared to term pregnancies, particularly during the late luteal phase. In four out of the five additional reproductive cycles included in the current study where females were bred but no birth occurred, active ceruloplasmin in urine increased during the luteal phase. Similar to the known lost pregnancies, the temporal pattern of change in urinary ceruloplasmin during the luteal phase deviated from the term pregnancies suggesting that these cycles may have also been lost pregnancies. Among giant pandas in captivity, it has been presumed that there is a high rate of pregnancy loss and our results are the first to provide evidence supporting this notion.
    • Urinary profiles of progestin and androgen metabolites in female polar bears during parturient and non-parturient cycles

      Knott, Katrina K.; Mastromonaco, Gabriela F.; Owen, Megan A.; Kouba, Andrew J. (2017)
      Due to the environmental and anthropogenic impacts that continue to threaten the reproductive success of polar bears, a more detailed understanding of their reproductive cycle is needed. Captive populations of polar bears provide an excellent opportunity to learn more about the reproductive physiology of the species. Progestin (P4) and androgen (T) metabolites in urine, and their ratio (P4:T), were examined during 11 reproductive cycles of captive female polar bears (n = 4) to characterize the steroid hormone profile during pregnancy and determine possible variations related to reproductive failure. The concentration of hormone metabolites in urine were determined through enzyme immunoassay. Reproductive cycles were classified as pregnant (n = 3), anovulatory (n = 4) and ovulatory-non-parturient (n = 4) based on the changes in urinary hormone metabolite values and cub production. In the absence of a lactational suppression of estrus, elevated androgen concentrations suggested resumption of follicular development within 3 weeks of parturition. Breeding behaviours were most often observed when androgen values were at their highest or in decline. Ovulation was identified by a return to basal androgen concentration and elevation of progestins within 1–4 weeks after breeding. As a result, urinary concentrations of progestins were greater than androgens (P4:T ratio ≥ 1.0) during ovulatory cycles whereas the P4:T ratio was <1.0 when females were anovulatory. Progestins and the P4:T ratio of parturient cycles were greatest beginning in June/July (17–20 weeks after breeding) and reached a peak at 24–37 weeks (mid-October/mid-November, 4–9 weeks before birth of cubs). Non-invasive monitoring of hormone metabolites in urine provided a rapid determination of endocrine function for improved husbandry and reproductive management of polar bears in captivity. Further research is warranted to understand the reproductive endocrinology of polar bears and its impact on conservation and management of this species in captivity and the wild.
    • Vocal cues to male androgen levels in giant pandas

      Charlton, Benjamin D.; Keating, Jennifer L.; Kersey, David; Rengui, Li; Huang, Yan; Swaisgood, Ronald R. (2011)
      Little is known about the potential of non-human mammal vocalizations to signal information on the hormonal status of the caller. In the current study, we used endocrine data and acoustic analyses to determine whether male giant panda bleats provide reliable information about the caller's current androgen levels. Our results revealed significant relationships between acoustic features of male giant panda bleats and the caller's faecal androgen metabolite concentrations….