Analysis of urinary immunoreactive steroid metabolites and gonadotropins for characterization of the estrous cycle,breeding period,and seasonal estrous activity of captive killer whales (Orcinus orca)

To increase the basic understanding of killer whale (Orcinus orca) reproductive physiology necessary for the development of artificial breeding programs, we utilized radioimmunoassays (RIA) to detect urinary immunoreactive steroid metabolites (pregnanediol-3α-glucuronide [PdG] and estrone-conjugates [EC]) and gonadotropins (luteinizing hormone [LH] and follicle-stimulating hormone [FSH]) in urine samples from six female killer whales. Urine samples were collected from the whales by voluntary presentation behavior over a 2- to 4-year period. All urinary hormone values were corrected for intersample urine concentration variations by indexing with creatinine. Daily urine samples from four whales were collected during two conceptions and 18 complete estrous cycles. LH, FSH, EC, and PdG immunoreactive levels were determined and combined with observed copulatory activity in five cycles, including two conceptive cycles from two whales. Mean luteal phase lengths ranged from 9.7 to 19.2 days. Mean follicular phase lengths ranged from 6.5 to 16.8 days. Mean estrous cycle lengths based on the first detectable PdG levels were 41.6 ± 6.72 S.E.M. days. After PdG nadir, immunoreactive FSH levels showed a bimodal pattern with the first peak being greater in size, and both preceding a follicular phase EC increase. LH levels > the 95% confidence interval of the mean were considered significant. Combined LH immunoreactive values from whales 2 and 6 during two and three estrous cycles, respectively, had significant LH peak concentrations on day minus 2. These significant LH peaks were assumed to represent the preovulatory LH surge. Eight copulations during two conceptive cycles were observed between whales 2 and 6 and a breeding male. Six of these copulations (3 with each female whale) occurred within 72 hours of the beginning or the end of the presumptive preovulatory LH surge. Estrous activity was seen throughout the year for the herd. However, individuals had varying periods of anestrus that could not be linked to environmental, social, or nutritional influences. The whales that were reproductively successful had anestrus intervals that were usually influenced by gestation, postparturient period, or lactation. The information obtained during this research enhances the foundation for future artificial reproductive management techniques. © 1993 Wiley-Liss, Inc.     

神经激肽B对哺乳动物GnRH脉冲发生器的调节

哺乳动物的生殖功能受体内状态和外部环境综合作用的影响,这种综合作用通过错综复杂的神经内分泌系统最终汇集于促性腺激素释放激素(GnRH)系统从而影响下丘脑-垂体-性腺(HPG)轴的状态。神经激肽B(NKB)目前被认为是除kisspeptin外,调控GnRH脉冲分泌的又一关键因子。大量研究证实,NKB能够影响GnRH和促黄体激素(LH)的分泌,进而影响青春期的启动和生殖功能。然而,NKB对LH分泌的影响是刺激作用还是抑制作用尚存在争论。此外,NKB如何作用于GnRH神经元的信号通路尚不清楚,性激素是否参与这一生理过程,是目前的研究热点问题之一。本文就NKB及其受体的分布、神经网络结构、NKB对GnRH脉冲发生器的作用进行了系统的阐述,并针对目前尚待解决的一些问题进行了探讨。     

International Society for Wildlife Endocrinology: the future of endocrine measures for reproductive science, animal welfare and conservation biology

Hormone analysis is a precise and widely accepted tool for monitoring reproductive function and responses to stressors. Although hormones are present and can be measured in various biological matrices, non-invasive methods have gained popularity over the past 30 years as a more practical approach for assessing ovarian, testicular and, more recently, adrenocortical activity in intractable wildlife species. Non-invasive hormone monitoring also has been key to understanding biological mechanisms related to observed behaviours of captive and free-ranging animals. Despite the increasing popularity of this research field, wildlife endocrinologists have not had a specific forum for sharing and discussing their latest findings, technical developments and common challenges. To provide such a communication platform, the International Society for Wildlife Endocrinology (ISWE) was established in 2010, followed by an international meeting held on 3-4 November 2011 at the Toronto Zoo, Canada. Over several sessions, keynote speakers and participants discussed recent developments of new and innovative methods for hormone monitoring, as well as the latest advances in basic endocrinology as applied to adrenal function, reproductive physiology, animal health, ecology and evolution. Here, we introduce ISWE to the scientific community and discuss how this new society will serve as a resource for wildlife endocrinologists worldwide.     

Sexual behaviour and evolution of sexual dimorphism in body size in Jaera (Isopoda Asellota)

Individuals of the genus Jaera do not mate at random. In the species from the Mediterranean group, J. italica and. J. nordmanni, large males and medium sized females are at an advantage and their sizes are positively assorted. These effects are attributable to sexual competition between males. In the Ponlo-caspian species J. istri, no advantage of large males exists, but sexual selection could be the cause for a long passive phase prior to copulation and for normalizing selection upon female size at pairing. In the Atlantic species, J. albifrons, no selection can be ascertained.
Differential mating success in males appears as one of the causes of the evolution of sexual dimorphism in body size, which makes males larger, of equal size, or smaller than females according to the species. The reason for this reversal in dimorphism seems to differ in the two sexes. Sexual selection provides an explanation for the evolution of male size, while the interspecific changes in female length are more likely due to ecological factors.     

Density dependence of developmental instability in a dimorphic ungulate

The use of fluctuating asymmetry (FA) for biomonitoring environmental stress is limited by the lack of work on how FA in particular traits responds to specific stresses. Here, by manipulating the number of individuals in an enclosed fallow deer (Dama dama) population, we describe, for the first time, clear density dependence in the FA of juvenile jaw morphology. The impact of high population density on FA was strong for both sexes, supporting the use of FA for indexing environmental stress. In addition, there was some indication that the change in FA was greater in males (43.6%) than females (28.5%). Finally, the ability to buffer density-dependent stress was independent of body condition. We suggest that, under highly limiting conditions, whole cohorts may be unable to buffer against developmental error, irrespective of individual quality.     

Initial reproductive investment and parental body size in Cryptocercus punctulatus (Dictyoptera: Cryptocercidae)

Abstract. Females of the subsocial woodroach Cryptocercus punctulatus Scudder generally have a single oviposition period during which they produce one to four oöthecae. Monogamous pairs and their recently deposited oöthecae were collected in the field, and measured, weighed and analysed for nitrogen in the laboratory. Females put 9.8 ± 2.4% (mean ± SD) of their dry weight and 11.6 ±0.5% of their body nitrogen into oöthecae. The total nitrogen and dry weight of the brood were positively related to the post-oviposition total nitrogen and dry weight of the mother. A female's investment, on a per nymph basis, averaged 0.06% of her post-oviposition dry weight. Females may be able to recover up to 58.7% of the nitrogen invested into a brood by consuming the egg cases after hatch. Overall, there was little variation in the width of head capsules of adults in this species, and this parameter was not significantly different between the sexes. Females were heavier than males (dry weight) (P = 0.06). Within pairs, the weights and nitrogen contents of males and females were positively correlated, probably because they feed together in the same log for nearly a year prior to reproduction.     

Steroid imprinting and modulation of sexual dimorphism in the luteinizing hormone-releasing hormone neuronal system

Summary 1. Sex differences in the control of gonadotropin secretion and reproductive functions are a distinct characteristic in all mammalian species, including humans. Ovulation and cyclicity are among the most distinct neuroendocrine markers of female brain differentiation, along with sex behavioral traits that are also evident in different species.2. The luteinizing hormone-releasing hormone (LHRH) neuronal system is the prime regulator of neuroendocrine events leading to ovulation and hormonal changes during the menstrual cycle and, as such, is the potential site where many of these sex differences may be expressed or, at the very least, integrated. However, until recently, no significant differences were seen in LHRH neurons between male and female brains, including cell number, pattern of distribution, and expression of message or peptide (LHRH) levels.3. Recently, we reported that galanin (GAL), a brain-gut peptide, is coexpressed in LHRH neurons and that this coexpression is sexually dimorphic. When GAL is used as a marker for this neuronal system, it is clear that estradiol as well as progesterone profoundly affects the message and expression of the peptide and that this regulation, at least in rodents, is neonatally predetermined by gonadal steroid imprinting.4. Changes in GAL expression and message can also be seen at puberty, during pregnancy and lactation, and in aging, all situations that affect the function of the LHRH neuronal system. Using an immortalized LHRH neuronal cell line (GT1) we have recently observed that these neurons express estrogen receptor (ER) and GAL and that estradiol can increase the expression of GAL, indicating functional activation of the endogenous ER.