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The Endocrinology Laboratory has a variety of research projects involving fecal steroid analysis and behavior in ibexes, elands and oryxes, effects of endocrine disruptors on snails, and determination of hormones and drugs in water supplies. The lab continues to do projects reproduction and stress in cattle. |
Current research topics
Animal endocrinology
- Capra nubiana
- Oryx Dammah
- Taurotragus oryx
- Dama mesopotamica
- Ceratotherium simum simum
- Cyprinus carpio
- Sphincterochila zonata
- Sphincterochila prophetarum
1. Endocrine correlates of rank and reproductive status in male and female Nubian ibexes (Capra nubiana). Study conducted by Dorit Shargil, M.Sc., Bar Ilan University.
Non-invasive determination of hormone concentrations is a valuable tool for studying behavioral and reproductive parameters in wildlife. We monitored fecal progesterone, testosterone and estrogen levels in a captive herd of 26 adult Nubian ibex held on 250 ha tract, in order to investigate the hormonal correlates of behavior. The study was conducted over a 20 month period, and including two mating seasons, during which time we collected 147 fecal samples and 650 h of behavioral observations. The social hierarchy (N=17, 2002; N=14, 2003) was linear with age in adult males and nearly linear in adult females (N=9, 2002, 2003). High ranking males were in solitude, but females were aggregated. Higher ranked females gave birth later in the season. Testosterone titers in males peaked in the early part of the mating season, and declined gradually thereafter; and were positively correlated with rank. Testosterone was highest in the non-breeding season in females and testosterone titers positively correlated with rank in both sexes. Progesterone and estrogen titers were positively correlated with stage of pregnancy in females and, increased with rank in both male and female. High fecal testosterone in pregnant females was associated with male fetuses, while higher fecal progesterone was associated with multi-parity and female fetuses. Field study of a wild 25 ibex herd indicated that fecal steroid hormone profiles were similar to those observed in the captive herd.
Ibex
2. Endocrine correlates of rank and reproductive status in male Oryx dammah. Study conducted by Naama Berg, M.Sc. student, Bar Ilan University.
This study involved the collection of fecal testosterone and corticosterone from 11 male adults in the Oryx dammah population in the Safari National Zoological Park in Ramat Gan. The correlation between hormone levels and social hierarchy of the male population was investigated. Social ranking was determined by observation using Ad Libitum and Focal animal techniques, while hormones were extracted from the feces and levels measured by RIA and ELISA techniques. The herd was divided into four social groups: dominant, other males within the herd, inferior within the herd and outcasts. No correlation between hierarchy and the hormones in male oryx was found. On the other hand, a positive correlation between corticosterone and environmental conditions was observed. This is the first study to investigate the relationship between social rank and corticosterone in ungulates. The Oryx dammah is a species without a set estrous cycle, however it is known to have a post-partum estrus occurring three days after parturition. A positive correlation between testosterone and parturition was observed. The results suggest that stress and sex hormones in the male oryx are more influenced by environmental conditions, and the female physiological state than by male social status.
Oryxes
3. Endocrine correlates of rank and reproductive status in male common eland (Taurotragus oryx). Study conducted by Rotem Lavi, M.Sc. student, Bar Ilan University.
In the last few years, much effort has been made to reestablish and preserve the Taurotragus oryx (elands) population in Israel because of the importance of its feeding behavior in reducing ground foliage as a method of fire control. Elands are hierarchal with the males present always present herd and the females are polyseasonal but tend to calf in the spring in captivity. The aim of this study was to understand herd formation and social structure status by using sex (testosterone) and stress hormone (corticosteroid) level of the herd's male individuals (N=7) in captivity. Social hierarchy was determined by 120 hours of detailed observation of the interactions of each individual within the herd. Using this data we determined the social status of the herd. Hormone extraction was carried out from individual feces. Testosterone was determined by RIA and corticosterone was determined by ELISA. The results show that corticosterone and testosterone can be measured in feces of eland. There was a direct relationship between hormone levels and number of interactions and exposure to females, apparently due to rise in aggression. We also found that dominant males have a rise in testosterone level within few weeks of calving, and a month before inferior males.
Eland
4. Affect of sleeping arrangements on male white rhino behavior and hormone levels at the Tisch Family Zoological Gardens in Jerusalem (the Jerusalem Zoo). Study conducted with Noam Werner, Jerusalem Zoo.
Keeping all-male groups in zoos often eases the problem of surplus males in captive breeding programs of polygynous species. However, the welfare of the males in these species might be compromised when kept in a social structure that is not always natural. The Jerusalem Zoo holds two male southern white rhinos (Ceratotherium simum simum), in which males are considered solitary. Preliminary observations at the Zoo suggested that the males' sleeping arrangements, in adjacent compartments in the night house, may stress them because they cannot avoid each other's scent or voice, two major components of rhino communication. Hence, we tested the affect of the sleeping arrangements on the males' welfare by allowing each male to sleep outdoors for a period of about three weeks while his exhibit mate sleeps indoors. A similar period, when both males slept indoors, served as a control. We assessed welfare by measuring corticosterone (stress) and testosterone (sex) hormone levels in the feces, and by conducting behavioral observations. The results showed normal and stable corticosterone levels, except for a brief high peak for the dominant male when the two were re-united for the nights. In contrast, testosterone levels varied significantly between manipulations, dropping to non-breeding levels when both males slept indoors. This change corresponded with behavioral changes that suggested that the males were less relaxed. Also, relative changes in corticosterone levels suggest that the males treat the house as the most important part of the territory or even as an independent one. We expect that these results may affect future rhino exhibit design and husbandry recommendations in other zoos.
One finds friends where one can.
5. The reintroduction of the Persian fallow deer to the Soreq Valley: the mutual influence between the reintroduced animal and the surrounding habitat. Study conducted by Royi Zidon, M.Sc. student, Hebrew University.
Persian fallow deer are being reintroduced to nature in the Jerusalem hills. The deer come from a zoo with constant exposure to humans or a zoo where exposure was limited. The concentration of fecal corticosterone was elevated in the animals reintroduced compared with their counterparts which remained in the zoos. The levels of corticosterone were much higher in the fallow deer from the zoo with high human exposure than in the low exposure zoo. This increased stress level may be related to the much higher failure rate of reintroduction from the high exposure zoo.
Fallow deer Dama mesopotamica
6. The presence and effect of endocrine disruptors on reproductive organs of fish in a reservoir used for aquiculture . In cooperation with M. Gophen, Migal Technoligies.
A reservoir receiving some sewage water from an urban area, in addition to fresh water sources, was used for raising three species of fish. Prior to the introduction of the fish, the reservoir water contained appreciable amounts of testosterone, estrogen, ethinylestradiol and medroxyprogesterone. After introduction of the fish the level of hormones and drugs was reduced to nearly non-detectable levels while in a control reservoir without fish, the levels of the compounds remained constant. Of the three species studied, after eight months only the female carp developed gonads, which were small for body size. Observations suggest that the fish absorb the hormones and drugs in the early growing season and this has a negative effect on their reproductive development. When the male carp were transferred to a uncontaminated pond, their gonads developed normally.
 
male gonad female gonad
Cyprinus carpio
7. Endocrine parameters of reproduction in land snails. Study conducted by Galit Alon, M.Sc. student , Bar Ilan Univerisity
The steroidal hormonal profiles of two sympatric species of desert snails, Sphincterochila zonata and Sphincterochila prophetarum were determined at three ecophysiological-behavior stages:a estivation, cryptobiosis and active-feeding phases. Live snails were collected in their natural habitat every month for 13 months, the corpi removed and extracted with organic solvents and the progesterone, testosterone and estrogen determined by radioimmunoassay. In both these hermaphroditic species during aestivation, a peak of testosterone followed by a peak of estrogen was observed. During the brief active intervals, minor peaks of estrogen were also observed but these were much lower than seen during aestivation. Although the two species have different microhabitats during aestivation, there was little difference in the hormonal profile, although S. prophetarum had about two fold higher progesterone concentration than S. zonata.
 
S. Zonata with and without shell.
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Egg sac in situ Egg sac expressed
Environmental studies
Upper Catchment of Jordan River
1. Hormone transport in the Upper Catchment of the Jordan River
We examined if estrogen (estradiol+estrone) and testosterone could identify animal sources of pollution and that the presence of a contraceptive agent, ethinylestradiol would identify human sources of pollution in a watershed. Estrogen was expected to bind tightly to the soil and be found primarily in surface runoff while testosterone was expected to reach the groundwater. We therefore initially sampled twenty-four sites in the Upper Jordan Valley after each major rain event (four times). It was found that testosterone (>1 ng/L, max 5 ng/L) was present in over 90% of the samples. Estrogen (estrone and estradiol) was present (> 1ng/L, max 5.6 ng/L) in 26% of the samples. The highest values of testosterone and estradiol were obtained in streams receiving effluent from cattle pasture. Samples from an additional 6 sites in the Lower Jordan River receiving sewage water indicated a strong correlation of high BOD and fecal coli counts with a high level (6 ng/L) of ethinylestradiol.
At the start of the rainy season, there was a large increase in the concentration of testosterone and estrogen in the Upper Jordan River Catchment that declined over the next three months to non-detectable levels (<0.3 ng/L). Samples taken from 10 secondary and tertiary feeder streams in a 30 km3 area indicated that testosterone extinction time was in the order of 4 months while estrogen had was undetectable after two weeks. Since both compounds came from the same source, this would indicate that testosterone and estrogen leave the environment by different routes. The hormones, specifically estradiol and ethinylestradiol, were detected at levels near or above the amounts known to affect plants and fish. Since all of the compounds can be measured rapidly and inexpensively in a standard laboratory, this method could be used to differentiate between organic pollutant sources in any defined watershed
2. Contamination of Israel’s rivers with steroid hormones (naturally occurring and synthetic. Study conducted by Keren Cohen-Barel, M.Sc. student, Tel Aviv University.
Natural (estradiol, estrone, testosterone, estriol) and synthetic hormones (ethinylestradiol) are constantly excreted into the environment from human and animal sources but little is known of their transport. The purpose of this study was to determine how far along a 100 km river course that hormones could be detected after contamination with sewage effluent or fishpond effluent. Fourteen sites in the Lower Jordan River drainage were sampled (2 sites above the sewage effluent contamination, 8 sites below the contamination and 4 tributaries) before and after the dry season of 2002 (Spring and Fall). Samples were tested for testosterone, estrogen (estrone and estradiol combined), estriol, ethinylestradiol, ammonia and fecal coli. It was found that the fecal coli count dropped exponentially (from 250,000 to 60/ 100 ml3) and the ammonia dropped from 15 to less than 1 mg/l over the initial 25 km stretch. Over the same stretch, the hormone values declined by half from their maximum values for testosterone (3.3 ng/l), estriol (8.8 ng/l), ethinylestradiol (6.1 ng/l), and estrogen (4.9 ng/l). From the 67 to 100 km mark, testosterone (4.8 ng/l) and estrogen (2.4 ng/l) were still elevated while ethinylestradiol and estriol were ³ 1.5 ng/l. The high level of testosterone and estrogen between the 67 to 100 km marks was probably due to major discharge from fishponds between the 23 to 27 km marks. Levels of ethinylestradiol above 1 ng/l, a level which can affect fish, was seen in 70% (12/16) samples tested. The data suggests that hormones in readily measured quantities can be transported considerable distances from the source of pollution
3. Transport of testosterone, androstenedione and estrogen in the vadose zone underlying a dairy waste lagoon. In cooperation with Ben Gurion University.
Testosterone, androstenedione and estrogen are present in animal manures and are constantly excreted into the environment. Previous reports have indicated the inter-convertible estrogens, estradiol and estrone, are immobile in soil while, of the two androgens, - testosterone is mobile and reaches the groundwater and androstenedione is partially mobile. To study the transport of these compounds in the vadose over long time exposure (30 yr), we studied a dairy barn with 50 dairy cattle. This was calculated as a load of 36 kg estrogens and 7 kg androgens. All of the effluent was released into 15 x 10 m lagoon, which drained toward a dry creek, creating a constant overflow of about 300 meters long and 1-4 meters wide. The lithology under the waste lagoon consists of 8 m of clay layer on top of sand and calcareous formation and the water table was at a depth of 47 m. Soil samples (5 g) were extracted with organic solvents and analyzed using radioimmunoassay or Elisa. Groundwater samples (500 ml; after pumping four well volumes) were extracted on C-18 solid extract columns and similarly analyzed. It was found that testosterone was present (>50 ng/kg) from the top soil throughout the vadose zone to the water table. Estrogen was above 50 ng/kg to a depth of 25 m (range 50 to 100 ng/kg) and androstenedione was present to 5 m. Testosterone and estrogen, but not androstenedione, were present in the groundwater (3 ng/l). The level of the steroids in control soils and groundwater taken 1 km upstream from the site were below the limit of detection. We conclude that unlike previous reported, estrogen can be transported in the vadose zone and can reach the groundwater after long time exposure to dairy barn effluents. The concentrations of estrogen observed were above the amount known to affect soil bacteria and aquatic fauna.
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