To determine if elevated concentrations of waterborne selenium (Se), caused by coal mining, in the Elk River in southeastern British Columbia, may be causing reproductive or teratogenic effects in wild cutthroat trout (Oncorhynchus clarki lewisi), fertilized eggs from exposed and reference fish were raised in the laboratory. Eggs from each female were reared separately and the percent mortalities and deformities were related to the selenium content of the eggs. Selenium concentrations in females from the exposed site were highest in the liver (36.6 +/- 22.5 microg/g dry weight, range: 18.3 to 114), followed by the eggs (21.0 +/- 18.3 microg/g, range: 8.7 to 81.3) and the muscle (12.5 +/- 7.7 microg/g, range: 6.7 to 41). Despite these elevated egg Se concentrations, there was no significant effect on fertilization; time to hatch; percent hatch; or egg, larvae, and fry deformities or mortalities. Reproductive failure and embryonic terata have been reported at much lower egg Se concentrations in other fish species. The lack of any toxic response in this study may be due to an evolved tolerance to higher tissue Se concentrations in a population of fish living in a seleniferous river system.
Serum levels of LH and progesterone were measured by radioimmunoassay and competitive protein binding techniques respectively in nonmated, sterile-mated (to a vasectomized male) and fertile-mated female beagles. There were no differences in the pattern of LH secretion in the non-pregnant and pregnant animals. The levels of LH were elevated for approximately 4 days, with the peak concentration (2 7 ± 5.2 ng/ml) occurring on the day prior to the first day of standing estrus. At all other times, LH remained between 2-4 ng/ml. Ovulation was observed late on the first day of standing estrus or nearly 24 hr after the LH peak. By 10 days after the LH peak, the concentration of progesterone had increased to 20-30 ng/ml in the nonpregnant and pregnant dogs. In all nonpregnant animals, the pattern of progesterone secretion after day 10 was similar: decreasing from day 10 and subsequently waning to nondetectable levels (<0.5 ng/ml) by 80 days after the LH peak. On the other hand, in the pregnant dogs, progesterone levels generally decreased 10-15 days after the LH peak but then increased dramatically to reach maximum levels (47 ± 3.1 ng/ml) 20-25 days after the LH peak. Progesterone concentration then gradually decreased to nondetectable levels by the day following parturition (day 65). These results suggest: a) the formation of functional corpora lutea is not dependent on mating, and they can remain functional beyond the normal time of parturition (80 vs 65 days), b) the patterns of LH and progesterone do not differ in overt pseudopregnant dogs (those that lactate) and covert pseudopregnant dogs (those that don't lactate) and c) some factor, perhaps from the placenta, may stimulate the corpora lutea of pregnancy 15-25 days after the LH peak. (Endocrinology 94: 404, 1974) T HE reproductive cycle of the dog is characterized by the following events: first, the dog has only one estrous cycle during the breeding season, and it is characterized by rather lengthy periods of proestrus and estrus, each lasting from 5-12 days
Progesterone was determined daily in the peripheral plasma of six cows for a total of seven complete oestrous cycles. Progesterone levels ranged from less than 0\m=.\5 ng/ml plasma during the follicular phase to 6\m=.\6 ng/ml plasma (6\m=.\1 to 10\m=.\2 ng) at peak luteal phase. Progesterone levels in cows with 21-day cycles increased rapidly from Day 3 to Day 8 (oestrus = 1) with a much slower rate of increase from Day 8 to Day 17. These cows showed a progesterone decrease of more than 50% from the previous day on Days 18 (two cows), 19 (one cow) and 21 (two cows). Two other cows with cycles of 22 and 23 days' duration both had a similar decline on Day 20. A variable time interval of 1 to 5 days was observed between the decline of progesterone and the occurrence of oestrus. These data indicate that considerable variation may exist among cows as to time requirements for follicle development and maturation. Monitoring of peripheral levels of progesterone is suggested as a means of studying corpus luteum function.
SUMMARY A method was adapted for the quantitative determination of progesterone obtained from the peripheral plasma of several domestic animals (cow, gilt and ewe). The technique utilized the detection of a chloroacetate derivative of 20β-hydroxypregn-4-en-3-one (enzymically converted from progesterone) by gas—liquid chromatography with electron capture detection. An improved extraction procedure is presented in which the plasma extract is saponified instead of the plasma; this was particularly effective for the removal of the yellow pigments normally found in large amounts in bovine plasma and allowed one-step isolation of progesterone by thin-layer chromatography. Progesterone levels in the peripheral plasma during the follicular phase of the oestrous cycle of the cow, gilt and ewe averaged 0·4 ng./ml., 0·5 ng./ml. and 0·2 ng./ml., respectively. Luteal phase levels of progesterone averaged 6·6 ng./ml., 27·1 ng./ml. and 2·1 ng./ml. in the cow, gilt and ewe, respectively. Progesterone increased during gestation in one cow from 4·7 (sixth month) to 6·1 ng./ml. plasma (eighth month). No evidence was obtained for a pre-ovulatory rise of progesterone in one cow during the 12 hr. immediately following oestrus. It is suggested that corpus luteum function can be monitored in domestic animals during the oestrous cycle by the daily estimation of progesterone in the peripheral plasma.
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