Endocrine, gonadal and behavioral responses of male crucian carp to the hormonal pheromone 17 alpha,20 beta-dihydroxy-4-pregnen-3-one

Extreme olfactory sensitivity of silver and bighead carp to overlapping suites of 21-carbon steroids suggests that these species, and likely all other Cyprinoidei, employ them as pheromones

Although well established that several fishes including goldfish in the suborder Cypinoidei within the family Cypriniformes use the maturation-inducing steroid 17,20β-dihydroxy-pregn-4-ene-3-one (17,20βP) and its metabolites as a priming pheromone which they detect with sensitivity and specificity, it is unclear whether and how other Cypriniformes might have evolved to do so. This study examined this question in the family Xenocyprididae. Using electro-olfactogram recording we tested the olfactory sensitivity of silver (Hypophthalmichthys molitrix) and bighead carp (H. nobilis) to a range of 213 steroids in 21 mixtures at 10-9M. While silver carp detected 6 of 21 mixtures, bighead carp detected 5 (p< 0.05). Silver carp were sensitive to 13 21-carbon steroids in these mixtures including 17,20βP while bighead carp detected 9, including 8 detected by silver carp. This assortment of steroids overlapped that detected by goldfish (family Cyprinidae) but no non-Cyprinoid, suggesting common evolutionary origin and function with differences characteristic of species-specificity.

Functional evaluation of a novel kisspeptin analogue on the reproduction of female goldfish

Kisspeptin (kp) is a key regulator of reproduction, which stimulates sexual maturation and gametogenesis in mammals, amphibians, and teleosts. In the present study, to enhance the biological activity of kp10, a novel analog (referred to as M-kp10) was designed based on the endogenous goldfish variant, in which phenylalanine 6 was substituted by tryptophan and the N-terminus was acetylated. Compared with the native kp-10 and salmon gonadotropin-releasing hormone (GnRH3), the effect of M-kp10 on sexual hormones and reproductive indices as well as the expression of kiss1, cyp19a1, and kiss1ra genes in goldfish (Carassius auratus) was investigated. In practice, peptides were synthesized based on the standard Fmoc-solid-phase peptide synthesis and purified by employing RP-HPLC, followed by approving their structure using ESI-MS. The results showed that M-kp10 increased significantly 17,20β-DHP, LH, FSH and E2 as well as fecundity, hatching and fertilization percentages than the other peptides. Histological studies revealed that M-kp10 led to the faster growth of ovarian follicles compared to the kp-10 and GnRH3. The genes of cyp19a1, kiss1ra, and kiss1 were remarkably more expressed after treatment with M-kp10. In conclusion, the results indicated the superiority of M-kp10 over kp-10 in inducing sexual maturation and accelerating the percentage of fecundity, suggesting that M-kp10 could be a promising candidate for application in the artificial breeding of fish.

Expression of reproductive-related genes and changes in oocyte maturation of goldfish broodstock (Carassius auratus) following injection of different exogenous kisspeptins

Kisspeptin, upstream of the hypothalamic-pituitary-gonadal axis, play an essential role in the reproductive process. In the present study, the effect of different types of kisspeptin, including goldfish (Carassius auratus) kiss1 kisspeptin (Kiss1), human kisspeptin (Hkiss) and their combination (Kiss1+H) on the reproductive-related genes (kiss1, Kissr and Cyp19) of adult female goldfish was investigated in comparison with Ovaprim (a synthetic GnRH hormone). Kiss1 and Hkiss were synthesized using a solid-phase synthesis approach. Peptides were injected at a dose of 100 μg/kg body weight. The brain and ovarian tissues of samples were separated for histological studies 24 hr post-injection. The expression of the kiss1, Kissr and Cyp19 genes was measured by RT-PCR. The results showed a significant increase in expression of the reproductive-related genes. Histological analysis revealed higher number of mature oocytes in kisspeptin treated groups compare to other ones. In conclusion, Hkiss and Kiss1+H are the most effective peptides in oocyte maturation and expression of reproductive-related genes. In addition, it seems that kisspeptins in other domestic animals can be used to stimulate the hypothalamus-pituitary-gonadal axis.

The effect of different exogenous kisspeptins on sex hormones and reproductive indices of the goldfish (Carassius auratus) broodstock

Despite several studies on fish hormone therapy, finding new candidates may provide more reproductive efficiency in artificial propagation. Kisspeptins, being upstream of the hypothalamic-pituitary-gonadal axis, appear to play a key role in the reproduction process. In the present study, the effect of different variants of kisspeptide, including goldfish (Carassius auratus) kiss1 kisspeptin (Kiss1), human kisspeptin (Hkiss), and their combination (Kiss1 + H), on the reproductive indices of goldfish broodstock in comparison to Ovaprim (a typical synthetic Gnrh hormone) was investigated. Peptides (Kiss1 and Hkiss) were synthesized using a solid-phase synthesis approach. Kiss1 and Hkiss were injected at a dose of 100 μg kg-1 body weight, blood samples were taken 6 h after injection and sex hormones (E2, Dhp, and 11-Kt), gonadotropins (Lh and Fsh), cortisol and reproductive indices (fecundity, fertilization and hatching percentage) were measured. The results showed a significant increase of plasma sex hormones and gonadotropins in fish treated with kisspeptins. In addition, the cortisol and lipoprotein lipase in Kiss1, Hkiss and Kiss1 + H were remarkably increased compared to Ovaprim. In conclusion, kisspeptins could be a more suitable candidate than Ovaprim for accelerating and synchronizing oocyte maturation in the fisheries industry.

Rapid sex steroid effects on reproductive responses in male goldfish: Sensory and motor mechanisms

Contribution to Special Issue on Fast effects of steroids. Although we have learned a great deal about the molecular mechanisms through which sex steroids rapidly affect cellular physiology, we still know little about the links between those mechanisms and behavioral output, nor about their functional consequences in natural contexts. In this review, we first briefly discuss the contexts associated with rapid effects of sex steroids on reproductive behaviors and their likely functional outcomes, as well the sensory, motor, and motivational mechanisms associated with those effects. We then discuss our recent studies on the rapid effects of testosterone in goldfish. Those studies indicate that testosterone, through its aromatization and the subsequent activation of estrogen receptors, rapidly stimulates physiological processes related to the release of milt/sperm through likely influences on motor pathways, as well as behavioral responses to female visual stimuli that may reflect, in part, influences on early stages of sensory processing. Such motor and sensory mechanism are likely important for sperm competition and mate detection / tracking, respectively, in competitive mating contexts. We also present preliminary data on rapid effects of testosterone on responses to pheromones that may not involve estrogen receptors, suggesting a dissociation in the receptor mechanisms that mediate behavioral responses in different sensory modalities. Lastly, we briefly discuss the implications of our work on unresolved questions about rapid sex steroid neuromodulation in fish.

Involvement of Membrane Progestin Receptor Beta (mPRβ/Paqr8) in Sex Pheromone Progestin-Induced Expression of Luteinizing Hormone in the Pituitary of Male Chinese Black Sleeper (Bostrychus Sinensis)

Our previous studies showed that 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) acted as a sex pheromone to induce reproductive success in Chinese black sleeper (Bostrychus sinensis), but its functional mechanism remains unclear. In the present study, we cloned the cDNAs of the gonadotropin subunits (cgα, fshβ, and lhβ), and found that, in exposure to 5 nM DHP, transcript levels of lhβ significantly increased in the pituitary at 6 h post exposure; plasma 11-KT levels increased at 24 h post exposure in mature male fish. In contrast, DHP exposure failed to increase the transcript levels of lhβ in the pituitary of immature male fish, suggesting that the responsiveness to DHP depends on reproductive status. Interestingly, expression of progestin and adipoQ receptor 8 (paqr8, also known as mPRβ) and progesterone receptor membrane component 2 significantly increased in the olfactory rosette of male fish at late meiosis stage following a co-injection of human chorionic gonadotropin (HCG) and luteinizing hormone releasing hormone-A₃ (LHRH-A₃), while no increases of other progestin receptors were observed. Moreover, Paqr8 protein was localized in the dendritic knobs of the olfactory sensory neurons, which were activated following the in vivo exposure to DHP. The DHP-induced expression of lhβ in pituitary was not inhibited by RU486, an antagonist of nuclear progesterone receptor. Taken together, our results suggested that sex pheromone DHP increased the expression of lhβ transcript in the pituitary and plasma 11-KT levels of mature male, important for reproduction; and Paqr8 might be involved in responding to sex pheromone DHP in the olfactory rosette of male B. sinensis.

Out-of-season production of 17,20β-dihydroxypregn-4-en-3-one in the roach Rutilus rutilus

In this study, although the highest production of two physiologically significant progestins in teleosts [17,20β-dihydroxypregn-4-en-3-one (17,20β-P) and 17,20β,21-trihydroxypregn-4-en-3-one (17,20β,21-P)] was observed in the period just prior to spawning in both male and female roach Rutilus rutilus, there was also a substantial production (mean levels of 5-10 ng ml(-1) in blood; and a rate of release of 5-20 ng fish(-1)  h(-1) into the water) in males and females in the late summer and early autumn (at least 7 months prior to spawning). During this period, the ovaries were increasing rapidly in size and histological sections were dominated by oocytes in the secondary growth phase [i.e. incorporation of vitellogenin (VTG)]. At the same time, the testes were also increasing rapidly in size and histological sections were dominated by cysts containing mainly spermatogonia type B. Measurements were also made of 11-ketotestosterone (11-KT) in males and 17β-oestradiol and VTG in females. The 3 months with the highest production of 11-KT coincided with the period that spermatozoa were present in the testes. In females, the first sign of a rise in 17β-oestradiol concentrations coincided with the time of the first appearance of yolk globules in the oocytes (in August). The role of the progestins during the late summer and autumn has not been established.

Sperm from pheromone primed brown trout (Salmo trutta L.) produce more larvae

Male goldfish (Carassius auratus) exposed to female hormonal pheromones express increased milt volumes and their sperm fertilize more eggs than sperm from unprimed males. Ovulated salmonid females also release odours that increase volumes of strippable milt in males. It is, however, not known if the priming pheromones affect the ability of sperm to fertilize eggs in salmonids. In this study, we compare the proportion of larvae produced from in vitro fertilization tests between primed brown trout (Salmo trutta) males exposed to a mix of female urine and ovarian fluids, and control males exposed only to 0.9 % sodium chloride. We also investigate priming effects on milt yield and sperm motility. Fertilization tests with sperm from single males, as well as sperm from two males (i.e., sperm competition), were performed. Primed males generated more larvae in both the single male and competition fertilization tests. No differences between treatments in milt yield and sperm motility could be established.

Male primer endocrine responses to preovulatory female cyprinids under natural conditions in Sweden

This study investigated two related aspects of male-female reproductive interactions in the family Cyprinidae: (1) whether ovulating female rudd Scardinius erythrophthalmus (subfamily Leuciscinae) induce endocrine and gonadal priming responses in conspecific males, a phenomenon which has been described only in species from the subfamily Cyprininae such as goldfish, Carassius auratus, crucian carp Carassius carassius and common carp, Cyprinus carpio and (2) whether the stimuli mediating these responses are species-specific. Field studies of three sympatric European cyprinids, two leuciscins (S. erythrophthalmus and white bream Blicca bjoerkna) and one cyprinin (C. carassius), were conducted on fishes captured in Sweden in the spawning season and held in net pens under natural conditions. As previously reported in C. carassius, male S. erythrophthalmus increased milt (sperm and seminal fluid) volume and plasma concentrations of the sperm maturation hormone 4-pregnen-17,20β-diol-3-one (17,20β-P) when they were held with female S. erythrophthalmus induced to ovulate by injection of Ovaprim (GnRH analogue plus dopamine antagonist). Male S. erythrophthalmus had larger milt volumes than male C. carassius prior to and following exposure to ovulatory conspecifics, but exhibited a smaller proportional milt increase in response to stimulation, suggesting species differences in sperm allocation at spawning. The presence of female S. erythrophthalmus and B. bjoerkna did not affect milt volumes of C. carassius under two experimental conditions: (1) ovulating S. erythrophthalmus and B. bjoerkna did not increase the milt volumes of C. carassius and (2) S. erythrophthalmus and B. bjoerkna did not interfere with the milt volume increase induced in male C. carassius by ovulating conspecifics. These results suggest that, as in C. auratus, C. carassius and C. carpio (subfamily Cyprininae), female S. erythrophthalmus (subfamily Leuciscinae) release a preovulatory pheromone that exerts priming effects on male hormones and sperm allocation. The findings also indicate that C. carassius discriminate between the reproductive odours of conspecifics and heterospecifics.

The role of the maturation-inducing steroid, 17,20beta-dihydroxypregn-4-en-3-one, in male fishes: a review

The major progestin in teleosts is not progesterone, as in tetrapods, but 17,20beta-dihydroxypregn-4-en-3-one (17,20beta-P) or, in certain species, 17,20beta,21-trihydroxy-pregn-4-en-3-one (17,20beta,21-P). Several functions for 17,20beta-P and 17,20beta,21-P have been proposed (and in some cases proved). These include induction of oocyte final maturation and spermiation (milt production), enhancement of sperm motility (by alteration of the pH and fluidity of the seminal fluid) and acting as a pheromone in male cyprinids. Another important function, initiation of meiosis (the first step in both spermatogenesis and oogenesis), has only very recently been proposed. This is a process that takes place at puberty in all fishes and once a year in repeat spawners. The present review critically examines the evidence to support the proposed functions of 17,20beta-P in males, including listing of the evidence for the presence of 17,20beta-P in the blood plasma of male fishes and discussion of why, in many species, it appears to be absent (or present at low and, in some cases, unvarying concentrations); consideration of the evidence, obtained mainly from in vitro studies, for this steroid being predominantly produced by the testis, for its production being under the control of luteinizing hormone (gonadotrophin II) and, at least in salmonids, for two cell types (Leydig cells and sperm cells) being involved in its synthesis; discussion of the factors involved in the regulation of the switch from androgen to 17,20beta-P production that seems to occur in many species just at the time of spermiation; discussion of the effects of in vivo injection and application of 17,20beta-P (and closely related compounds) in males; a listing of previously published evidence that supports the proposed new function of 17,20beta-P as an initiator of meiosis; finally, discussion of the evidence for environmental endocrine disruption by progestins in fishes.

Behavioral and olfactory responses of female Salaria pavo (Pisces: Blenniidae) to a putative multi-component male pheromone

The peacock blenny, Salaria pavo (Risso 1810), typically breeds in rocky shores of the Mediterranean and adjacent Atlantic coast. Males defend a territory around a hole or cavity wherein females deposit eggs that the male guards until hatching. A pair of exocrine glands on the anal fin (anal glands) of males produces a putative pheromone involved in attraction of reproductively competent females to the nest. We used behavioral assays to assess species-specific attraction of reproductively competent females to putative male pheromones, including the anal gland pheromone. Additionally, chromatographic fractions of anal glands and male-conditioned water were tested for olfactory potency in females by electro-olfactogram analysis (EOG). In a flow-through tank or fluviarium, reproductive females were attracted to male-conditioned water and to the anal gland macerate from conspecifics but not to those of a closely related heterospecific. In addition, attraction of reproductive females to conspecific anal gland macerate occurred only during their initial upstream movement in the fluviarium; this was an ephemeral response when compared with the response to male-conditioned water that attracted females throughout the entire period of observation (5 min). Reproductive females also were attracted during the entire period of observation to water-conditioned by conspecific males whose anal glands had been removed. However, the attraction was more variable than that to water conditioned by intact males. Moreover, females were not attracted to male (without anal glands) odor during their initial upstream movement in the fluviarium. Finally, non-reproductive females were not attracted to the conspecific anal gland macerate. The EOG responses of females to molecular weight fractions and solid-phase extraction and high-performance liquid chromatography fractions of anal gland macerates and male-conditioned water (with and without anal glands) suggest that the anal glands release hydrophilic odorants that consist mainly of molecules smaller than 500 Da. Furthermore, males released potent odorants that do not originate from the anal glands. We hypothesize that females respond to a multi-component male pheromone to find mates. The putative anal gland pheromone is possibly comprised of hydrophilic odorants, whereas the other component(s), presumably of gonadal origin, may be less water-soluble.

Endocrine and milt responses of male crucian carp (Carassius carassius L.) to periovulatory females under field conditions

Laboratory studies in domesticated goldfish (Carassius auratus) show that, during the preovulatory luteinizing hormone (LH) surge, females release a complex steroidal pheromone that induces in males a rapid increase of plasma LH, which in turn increases strippable milt (sperm and seminal fluid) prior to ovulation and spawning. The objective of this study was to determine if the same phenomenon occurs in a wild congener, the crucian carp (Carassius carassius), under field conditions where fish are held in natural waters under ambient temperature and photoperiod. During the spawning season in June 2003, crucian carp were trapped in a small pond near Uppsala, Sweden, and held separately by sex in floating net pens. Addition of untreated females to male pens did not change male LH concentrations or milt volume during the 17 h sampling period. In contrast, addition of females injected with Ovaprim (to induce an LH surge and ovulation) increased male LH concentrations at all sample times (5, 9, 13, and 17h) following female addition and increased milt volumes at all but the first (5h) sample time. Similar increases in male LH and milt that also occurred when untreated females ovulated spontaneously after addition to male pens suggest it is female ovulatory condition, rather than injection of ovaprim per se, that induced male LH and milt responses. Males also increased LH and milt 9h after addition of females injected with the goldfish pheromonal steroid 4-pregnen-17,20beta-diol-3-one (17,20betaP), suggesting that similar responses to ovaprim-injected females were due, at least in part, to release of preovulatory pheromonal steroid(s). The clear and consistent effects of ovulatory females on male LH and milt, and the fact that crucian carp adapted well to confinement, ovulated spontaneously, and exhibited apparently normal spawning behavior, all suggest that this species can serve as a useful cyprinid model to study reproductive processes in natural conditions.

Automated video analysis of age-related motor deficits in monkeys using EthoVision

Previous studies comparing age-related changes in locomotor function in nonhuman primates have generally relied on subjective human observations or rudimentary infrared motion sensors. Here, we used the automated video-tracking system EthoVision to objectively quantify locomotor activity in 6 young, 6 middle-aged and 12 aged female rhesus monkeys. The video records were analyzed for distance traveled, movement speed and vertical activity. Our results showed that the young monkeys (4.9 +/- 0.1 years old) traveled twice the distance and moved 48% faster than the middle-aged monkeys (15.7 +/- 0.5 years old), and traveled thrice the distance and moved 67% faster than the aged monkeys (26.3 +/- 0.9 years old). In addition, young monkeys were vertically more active (20/60 min) than both the middle-aged (7/60 min) and the aged (1/60 min) monkeys. Furthermore, the locomotor performance of the individual animals significantly correlated with increasing age for all three measures. We conclude that EthoVision is a reliable and objective tracking method for detecting age-related differences in locomotor movements in rhesus macaques, and possibly in humans.

Hormonally derived sex pheromones in fish: exogenous cues and signals from gonad to brain

Living in a medium that can limit visual information but readily exposes the olfactory organ to hormonal compounds released by conspecifics, fish throughout their long evolutionary history have had both clear cause and ample opportunity to evolve olfactory responsiveness to these potentially important chemical cues (hormonal pheromones). Indeed, water-borne steroids, prostaglandins, and their metabolites are detected with great sensitivity and specificity by the olfactory organs of diverse fishes, and exert important effects on reproductive behavior and physiology in major taxa including carps (goldfish), catfishes, salmon, and gobies. Best understood are goldfish, where periovulatory females sequentially release a preovulatory steroid pheromone and a postovulatory prostaglandin pheromone that dramatically affect male behavior, physiology, and reproductive fitness. Although the diverse array of hormonal products released and detected by fish indicates clear potential for species-specific hormonal pheromones, olfactory recordings showing similar patterns of hormone detection among closely related species provide little evidence of selection for specificity. By demonstrating that the actions of sex hormones and related products are not limited to reproductive synchrony within the individual, the relatively recent discovery of hormonal pheromones has considerably expanded our understanding of fish reproductive function, while providing valuable model systems for future study of olfactory function and pheromone evolution.

Physiological changes in the spawning gilthead seabream, Sparus aurata, succeeding the removal of males

The physiological effects triggered in females by the removal of males from a group of spawning fish were examined in the multiple batch spawner, the gilthead seabream, Sparus aurata. One week after the removal of males, a large portion of the oocytes underwent atresia, and sporadic release of low quality eggs continued at low frequency over a period of seven weeks. The transcript levels of the three native gonadotropin releasing hormone (GnRH) forms, salmon (s)GnRH, seabream (sb)GnRH, and chicken (c)GnRH-II, and the two beta GtH subunits were measured. Brain mRNA levels for all three GnRHs and pituitary beta LH mRNA levels significantly declined in the females as a result of removing the males compared to females that were maintained with males. Pituitary beta FSH mRNA levels showed the opposite trend and were significantly higher in females that were separated from males. Circulating levels of LH, testosterone, estradiol, 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one, and 17 alpha, 20 beta,21-trihydroxy-4-pregnen-3-one all declined in the group of females without males. These results imply the existence of an endocrine response to socio-sexual stimuli during the reproductive process in the gilthead seabream.

Influence of MHC on sibling discrimination in Arctic char, Salvelinus alpinus (L.)

The preference of juvenile Arctic char [Salvelinus alpinus (L.)] for odors from siblings and nonsiblings with different major histocompability complex class II (MHC) genotypes was studied in two-choice fluviarium tests. In the first part of the study, test fish demonstrated no preference for water scented by a sibling with a MHC genotype different from its own versus water scented by a MHC identical nonsibling. When both donors were siblings with different MHC genotypes, however, the test fish chose the water scented by the fish with the same MHC type as the test fish. The results suggest that odors with information about kinship are dependent on MHC but also on other, unknown factors. In the second part of the study, we observed that fish isolated since fertilization did not show any behavioral discrimination towards siblings, based on MHC genotype. One reasonable explanation for this result is that Arctic char learn to discriminate between odors from individuals of different MHC types.

Mature atlantic salmon (Salmo salar L.) male parr are attracted to ovulated female urine but not to ovarian fluid

The behavioral responses to urine and ovarian fluids from conspecific and heterospecific ovulated females were studied in mature Atlantic salmon (Salmo salar) male parr in a two-choice fluviarium. The males reacted differently to the stimulants. They spent more time in water scented by urine from salmon or brown trout (Salmo trutta L.) females compared to the time in water with ovarian fluids from salmon females. Furthermore, the males were attracted to salmon female urine (different from an indifferent reaction). Males exposed to urine of either species had higher plasma concentrations of testosterone (T) compared to unexposed controls. Measurement of the concentrations of prostaglandin F2alpha (PGF2alpha) and its major metabolite 15-ketodihydroprostaglandin F2alpha (15-ketodihydro-PGF2alpha) showed that the concentrations of the substances were higher in ovarian fluids of both species compared to those in urine. PGF2alpha showed a greater difference between ovarian fluid and urine than its major metabolite. The results suggest that urine of both species, in contrast to ovarian fluid, contain substances that attract mature Atlantic salmon male parr and that the active substances are neither PGF2alpha nor 15-keto-PGF2alpha.

Milt production in goldfish: regulation by multiple social stimuli

Previous studies in goldfish (Carassius auratus) demonstrate that milt (sperm and seminal fluid) volume is increased both by a preovulatory steroidal pheromone, 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta-P), that acts by increasing serum concentrations of gonadotropin II (GTH-II), and by a post-ovulatory prostaglandin (PG) pheromone, that acts by stimulating sexual interactions. Here, we show that male goldfish also increase milt volume when isolated for 24 h, or when placed with another male injected with human chorionic gonadotropin (hCG) for 12 h. In contrast to the milt increase induced by pheromonal 17,20 beta-P, the milt increase following isolation or exposure to hCG-injected males was not associated with increased serum GTH-II. Serum growth hormone also was unaffected, although serum testosterone increased in isolated males. The absence of GTH-II increase following isolation or exposure to hCG-injected males and the long latency time for these two types of responses, suggests these effects are mediated by a novel mechanism as yet undescribed. The present findings suggest that sperm competition has selected for complex mechanisms regulating milt production and fertility in goldfish: males regulate milt production not only in response to stimulatory pheromonal cues from ovulatory females, but also in response to unknown stimulatory and inhibitory cues from male competitors.

EthoVision: a versatile video tracking system for automation of behavioral experiments

The need for automating behavioral observations and the evolution of systems developed for that purpose is outlined. Video tracking systems enable researchers to study behavior in a reliable and consistent way and over longer time periods than if they were using manual recording. To overcome limitations of currently available systems, we have designed EthoVision, an integrated system for automatic recording of activity, movement, and interactions of animals. The EthoVision software is presented, highlighting some key features that separate EthoVision from other systems: easy file management, independent variable definition, flexible arena and zone design, several methods of data acquisition allowing identification and tracking of multiple animals in multiple arenas, and tools for visualization of the tracks and calculation of a range of analysis parameters. A review of studies using EthoVision is presented, demonstrating the system's use in a wide variety of applications. Possible future directions for development are discussed.

11-ketotestosterone induces male-type sexual behavior and gonadotropin secretion in gynogenetic crucian carp, Carassius auratus langsdorfii

To determine if a gynogenetic teleost might have a sexually bipotential brain, we tested whether implantation of 11-ketotestosterone (KT) induces male-type sexual behavior and gonadotropin (GTH) secretion in adult gynogenetic crucian carp, "ginbuna," Carassius auratus langsdorfii. KT-implanted female ginbuna were tested for male spawning behavior by pairing them with a stimulus female in which sexual receptivity and attractivity were induced by prostaglandin F(2alpha) (PG) injection. When KT-implanted female ginbuna were paired with a PG-injected stimulus female ginbuna, all the KT-implanted fish tested showed male spawning behavior in response to the PG-injected females. KT-implanted fish also showed female spawning behavior when they were injected with PG. When the KT-implanted female ginbuna were exposed to waterborne 17alpha,20beta-dihydroxy-4-pregnen-3-one (a female sex pheromone that stimulates male-typical GTH secretion in goldfish), all the KT-implanted fish showed an elevation of plasma GTH levels in response to the pheromone. These results demonstrate that gynogenetically evolved ginbuna, like goldfish, is sexually plastic and can be behaviorally and endocrinologically masculinized by androgen treatment without behavioral defeminization. These results support our hypothesis that adult teleosts retain a sexually bipotential brain regardless of reproductive strategy, i.e., hermaphroditism, gonochorism, or gynogenesis.