Influence of drinking water -- tap versus purified -- on embryo and fetal development in mice.

Pregnant CD-1 mice drank either chlorinated tap water obtained at NIEHS from the City of Durham, North Carolina municipal water supply or this same water passed in sequence through an organic removal cartridge and a demineralizer, followed by glass distillation. No significant overall differences in the reproductive status of pregnant mice were noted when the two groups were compared. Similarly, no significant overall influence on the incidence of malformed fetuses could be traced to the purity of drinking water. Month by month comparisons indicated that there were three statistically significant differences; all of which indicated improved performance for the mice that drank tap water. When the results for both groups were combined and a month by month comparison was made there was a significant difference in the pregnancy rate for February (68%) as compared with an overall pregnancy rate of 80% and a 79-93% spread for the other months, but the decrease was due to the low incidence of pregnancy in the group that drank the purified water.     

Initial studies on aBacillus subtilis mutant lacking the dnaK-homologue protein

A sequence of 412bp, spanning the terminal half of thegrpE and the proximal portion of thednaK-homologues inBacillus subtilis, was amplified with PCR technology. This fragment was cloned into pJH101, anEscherichia coli plasmid, and transformed intoB. subtilis strain YB886. Several chloramphenicol-resistant colonies were obtained from this transformation. The integration of the plasmid into theB. subtilis chromosome was verified by restriction endonuclease analysis and Southern hybridization. Strain BUL101, a chloramphenicol-resistant transformant, lacked the DnaK-homologue as demonstrated by two-dimensional polyacrylamide gel electrophoresis and Western blot analysis. BUL101 grew at slower rates than parental cells at both 37°C and 48°C, produced abnormal cell shapes at 48°C, and was unable to grow at 51°C. The 412bp fragment did not exhibit detectable promoter activity.     

Effects of subcutaneous melatonin implants on reproductive seasonality of farmed fallow deer (Dama dama)

A total of 18 fallow does, including pubertal, non-pregnant and pregnant adult does (6 per class), each received a single subcutaneous implant containing 18 mg melatonin on 4 occasions at 29-30-day intervals from 10 November 1986 (approximately 120-day treatment period). A further 18 contemporary does served as herd-mate controls. Two adult fallow bucks were treated the same and were run with the does until 16 March. Thereafter, 1 of 4 control bucks was run with the does until 1 June. Of the 6 pregnant does receiving implants within the last 40 days of their gestation, 4 failed to lactate after parturition in December 1986. The remaining 2 does successfully reared their fawns, as did the 6 contemporary controls. Mean (+/- s.e.m.) dates of first oestrus in 1987 were 27.6 February (+/- 3.0 days) and 22.9 April (+/- 0.8 days) for all treated and all control does respectively (P less than 0.001). Pubertal does were generally later to exhibit first oestrus than were older does within their respective treatment groups. Return oestrus occurred only in 2 pubertal does (1 treated and 1 control) with remaining does conceiving to their first oestrus, as verified by plasma progesterone profiles. However, 5 (28%) of the treated does and 3 (17%) of the control does failed to maintain pregnancy and fawn in 1987. The mean (+/- s.e.m.) 1987 fawning date of the remaining does was 22.4 October (+/- 2.7 days) for the treated group (N = 13) and 13.1 December (+/- 0.8 days) for the control group (N = 15; P less than 0.001). Mean (+/- s.e.m.) gestation length of treated does (238.9 +/- 0.6 days) was significantly longer than that of control does (234.5 +/- 0.4 days; P less than 0.001). Of 13 fawns born to treated does, 4 (31%) died within 24 h of birth (mainly due to hypothermia) whereas all 15 fawns born to control does survived to weaning. Melatonin-treated bucks exhibited a marked advancement of neck muscle hypertrophy during the treatment period and displayed normal rutting activity (e.g. vocalization) in response to early oestrus in the treated does.     

Structural requirements for steroid inhibition of sheep lymphocyte mitogenesis in vitro

The inhibitory effects of different steroids and related compounds on sheep peripheral blood lymphocytes (PBL) during exposure to the mitogen, phytohemagglutinin (PHA), have been measured by the reduction of [3H]thymidine incorporation into DNA. Dose-response curves showed that a maximum (or near maximum effect) was achieved at a steroid concentration of 12.5 microM. At this dose 19 of 41 compounds significantly reduced thymidine incorporation by activated PBL (P less than 0.01 to P less than 0.001). The greatest reduction was observed with 17-hydroxyprogesterone (-59%, i.e. reduced by 59% compared with vehicle control, 100%) greater than androstenedione greater than epitestosterone greater than estradiol-3-methyl ether greater than 20 alpha-dihydroprogesterone greater than medroxyprogesterone acetate greater than 5 beta-pregnane-3,20-dione greater than 5 alpha-pregnane-3,20-dione (-24%). Among the steroids which showed the greatest inhibitory effect, 6 had a 4-en-3-one group in ring A, 4 had a saturated ring A (pregnane or androstane) and one had a 3-methyl ether group and a phenolic ring A. The wide range of structures represented by these inhibitory steroids suggests that inhibition of lymphocyte mitogenesis involves more than one mechanism.     

Solar and UVC-induced mutation in human cells and inhibition by deoxynucleosides

Optimum conditions were established for quantitating the induction of hypoxanthine guanine phosphoribosyl transferase-deficient (HGPRT-) mutants in HeLa cells and in a human amelanotic melanoma cell line (MM96L). Compared at a fluence of equal toxicity (D37, fluence required to decrease cell survival to 37% of unirradiated control), noon sunlight in summer was slightly more mutagenic in MM96L than in HeLa cells (17 and 12 HGPRT- mutants per 10(6) survivors respectively). UVC (predominantly 254 nm) exhibited similar mutagenicity as equitoxic sunlight in HeLa but was 8-fold more effective in MM96L than equitoxic sunlight. Addition of a mixture of deoxyguanosine (20 microM), deoxyadenosine (20 microM), deoxycytidine (100 microM) and thymidine (20 microM) to the culture medium during the 7-day expression period following irradiation gave a 3-fold reduction in the UVC-induced mutation frequency of MM96L but not HeLa cells. The results suggest that these melanocytic cells are highly susceptible to mutagenesis by short wavelength UV, in a mechanism sensitive to deoxynucleosides.