An increased level of sperm abnormalities in mice with a partial deletion of the Y chromosome

Two congenic lines of mice, one with a partial deletion of the Y chromosome, differ in the percentage of spermatozoa with abnormal heads: B10.BR/SgSn males give 22.6% and B10.BR-Ydel/Ms males give 64.2% abnormal sperm. The F1s resulting from crosses of B10.BR/SgSn males with females of five common inbred strains exhibited significantly lower levels of abnormal sperm than the parental strains, as opposed to F1 hybrids sired by B10.BR-Ydel/Ms mutant males, where very high levels of abnormal spermatozoa were found. About 30% of abnormal spermatozoa, produced by males with deletion on the Y chromosome, were characterized by a flat acrosomal cap. This class of abnormality was never observed in non-mutant males, suggesting a mutant-specific defect. These results demonstrate the important role of the Y chromosome in spermatogenesis.     

Photolysis of 3-aryl-3-(trifluoromethyl)diazirines: a caveat regarding their use in photoaffinity probes.

The photolysis of 3-(4-tolyl)-3-(trifluoromethyl)diazirine in the presence of benzene, methanol, carbon tetrachloride, cyclohexane, triethylsilane, or diethylamine led to photoproducts consistent with the intermediacy of a singlet carbene. In the case of diethylamine, the photoinsertion into the N-H bond of diethylamine produced the expected adduct, 1-(diethylamino)-2,2,2-trifluoro-1-(4-tolyl)ethane. However, the base-catalyzed elimination of hydrogen fluoride from this adduct afforded an enamine, alpha-(diethylamino)-beta,beta-difluoro-4-methylstyrene, and the subsequent hydrolysis of this enamine furnished diethylamine and 2,2-difluoro-1-(4-tolyl)ethanone. This elimination and hydrolysis sequence effectively reversed the photoinsertion process. A similar photoinsertion and hydrolysis process using 3-(4-n-octylphenyl)-3-(trifluoromethyl)diazirine also produced 2,2-difluoro-1-(4-n-octylphenyl)ethanone in modest yield. These results suggest that the photoinsertion products from 3-aryl-3-(trifluoromethyl)-diazirines in biological systems may suffer similar fates limiting, in part, their utility in obtaining primary sequence data.     

Preferred ambient temperature for old and young men in summer and winter

To investigate the effects of age on thermal sensitivity, preferred ambient temperature (T _pref) was compared between old (71–76 years) and young (21–30 years) groups, each consisting of six male subjects in summer and winter. The air temperature (T _a) was set at either 20° C or 40° C at commencement. The subject was directed to adjust theT _a for 45 min by manipulating a remote control switch to the level at which he felt most comfortable. In the older group, theT _pref was significantly lower in trials starting at 20° C than that starting at 40° C in summer. The fluctuation ofT _pref (temperature difference between maximum and minimumT _a during the last 10 min) was significantly wider in the older group in both summer and winter. Repetition of the same experiment on each subject showed a poorer reproducibility ofT _pref in the older group than in the younger group in summer. Tympanic and esophageal temperatures of the older group kept falling throughout the trial starting at 20° C in summer. These results suggest that thermal sensitivity is decreased with advancing age and that thermal perception in the elderly, especially to cold, is less sensitive in summer.     

Ciliate protozoa in the rumen of Kafue lechwe, Kobus leche kafuensis, in Zambia, with the description of four new species.

The composition of the rumen ciliate fauna in 76 Kafue lechwe inhabiting a limited area in Zambia was surveyed and five genera containing 24 species with 16 formae belonging to the family Ophryoscolecidae were identified. Four new species belonging to Diplodiniinae were recognized and described as Diplodinium lochinvarense n. sp., Diplodinium leche n. sp., Diplodinium zambiense n. sp., and Metadinium ossiculi n. sp. In addition, Ostracodinium gracile form fissilaminatum Dogiel, 1932 was found for the second time and described as Metadinium fissilaminatum n. comb. The species composition was fairly unusual. Seven of the species have been found only in African wild antelopes and these species were found more frequently than cosmopolitan species. There was no evidence of isotrichid species. The average density of ciliates per 1 ml of the rumen fluid was 25.7 x 10(4), and the number of ciliate species per head of host was 10.8.     

Human endometrial stromal cells and decidual cells express cluster of differentiation (CD) 13 antigen/aminopeptidase N and CD10 antigen/neutral endopeptidase.

With specific monoclonal antibodies, we found that human endometrial stromal cells and decidual cells express two function-related surface antigens. Indirect immunofluorescence staining revealed that both endometrial stromal cells and decidual cells during the first trimester of pregnancy expressed cluster of differentiation (CD) 13 antigen and CD10 antigen, which are identical to aminopeptidase N and neutral endopeptidase, respectively. By flow cytometric analysis, CD13 antigen was detected on 82-93% of the examined cells, and CD10 antigen was detected on 75-93% of the examined cells in endometrial stromal cell-enriched preparations. Furthermore, peptidase activity was detected in these cell preparations by an assay based on the hydrolysis of alanine-p-nitroanilide into p-nitroaniline and alanine.     

Endothelin-3 stimulates production of endothelium-derived nitric oxide via phosphoinositide breakdown.

Cultured bovine endothelial cells (EC) have specific receptors for endothelin (ET)-3 functionally coupled to phosphoinositide breakdown. We studied whether ET-3 stimulates synthesis of nitric oxide (NO), an endothelium-derived relaxing factor that activates soluble guanylate cyclase in EC, and whether the ET-3-induced NO formation involves G-proteins. ET-3 dose-dependently stimulated production of intracellular cGMP in EC, of which effects were abolished by pretreatment with NG-monomethyl L-arginine, an inhibitor of NO synthesis, and methylene blue, an inhibitor of soluble guanylate cyclase. The stimulatory effects of ET-3 on cGMP production, inositol trisphosphate formation and increase in cytosolic free Ca2+ concentration were similarly blocked by pretreatment with pertussis toxin (PTX). These data suggest that ET-3 induces synthesis of NO mediated by phosphoinositide breakdown via PTX-sensitive G-protein in EC.     

Peculiarities of sexual reproduction inFagus crenata forests in relation to annual production of reproductive organs

Annual production rates of reproductive organs inFagus crenata forests in the lower area of the species' range were studied using 10 litter traps in 1980–1986. The production rates of dispersed pollen were estimated by multiplying the number of fallen male inflorescences per ha per year by the mean amount of pollen per inflorescence before anthesis. Large annual fluctuations in the production rates of male and female inflorescences were recognized, whereas their annual trends were synchronized with each other. Pollen production rates were within the range 1.0–6900 (mean: 1630)×10⁹ha⁻¹ yr⁻¹, the maximum/minimum ratio attaining 7000.F. crenata was the lowest producer of pollen among seven tree species studied: the number of pollen grains equivalent to a single ovule was in the range 6.0–14×10⁴. Furthermore, the mean dry weight of a single pollen grain (3.77×10⁻⁵mg) was higher than for wind-pollinated species. Three factors seemed to cause the low seed fertility ofF. crenata. The dry-matter production rate in the best seed year reached 3252 kg ha⁻¹ yr⁻¹, of which pollen accounted for 259 kg ha⁻¹ yr⁻¹. Unproductive years with less than 10% of the maximum production occurred four times in a 7-yr period. In such years there were fewer male and female inflorescences, and more fruit dropped as a result of insect damage. Lower nut dissemination would play an important role in suppressing any increase in nut predators, and fewer flowers would be produced to avoid wastage of photosynthates in a cool-temperate climate.