Effect of sex and the phase of the estrous cycle on intensity of injury and repair processes in the liver of rats with acute carbon tetrachloride poisoning

The pattern of injury and repair in the liver of Wistar rats depending on sex, the phase of the estrous cycle, and also under the conditions of deficiency of female sex hormones and after injection of -estradiol into ovariectomized rats was studied by morphometric, histo chemical, and electron-microscopic methods. Structural disturbances caused by CCl₄ were found to be increased and reparative reactions inhibited in the liver of females both during the period of a natural increase in the blood estrogen concentration and under the influence of exogenous estradiol, and ovariectomy also had a protective effect. In males, structural changes in the liver were more marked than in females with a low blood estrogen level and differend only a little from those in females during the period of increased secretion of sex steroids.Central Research Laboratory, Novosibirsk Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. P. Kaznacheev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 4, pp. 460–464, April, 1978.     

Melosis in holocentric chromosomes: Kinetic activity is randomly restricted to the chromatid ends of sex univalents inGraphosoma italicum (Heteroptera)

We have determined the number and location of the nucleolar organizing regions in spermatocytes ofGraphosoma italicum (2n=12A+ XY/XX) by means of silver impregnation, chromomycin A₃/distamycin A staining and fluorescencein situ hybridization. The identification of only one nucleolar organizing region located at one of the X chromosome ends has provided a suitable cytological marker to analyse the segregation of this univalent and that of the XY pseudobivalent during the first and second meiotic divisions respectively. Our results clearly show that at first meiotic metaphase the chromatids of the X chromosome are orientated with their long axes perpendicular to the polar axis. Although the kinetic activity is restricted to only one end in both X chromatids during the first meiotic division, both ends of the same chromatid have the same probability of showing such kinetic activity. In this sense, we also report that the chromatid segregation maybe initiated either at the same sister chromatid ends or at opposite ends in each chromatid. Thus, this indicates a sex chromatid independence as regards to the chromatid segregation during the first meiotic division. Throughout the second meiotic division both ends of the X chromatid are involved with the same probability in the end-to-end association to conform the XY pseudobivalent. This also implies a random localization of the kinetic activity at the ends opposite to those involved in the end-to-end association.accepted for publication by J. S. (Pat) Heslop-Harrison     

Sex determination and the maternal dominance hypothesis

The maternal dominance hypothesis has been derived from workwith humans which shows that women who are more dominant thanother women are more likely to conceive sons. In both animalsand humans dominance is a characteristic or personality trait,underpinned by testosterone and responsive to a range of environmentalchanges: physical, social and psychological. Studies of thesex ratio in the social sciences and animal behaviour eithersupport or are compatible with the idea that the sex-determiningrole of X- and Y-chromosome bearing spermatozoa may be precededby factors under maternal control which provide for differentialaccess of spermatozoa. Findings in reproductive physiology andphysiological psychology suggest that folh'cular testosteroneor a related hormone may play a critical role. Reproductivephysiologists have already identified maternal mechanisms whichcould provide the context for such a model.     

Effect of treadmill exercise on food intake and body weight in lean and obese rats

Body weight and food intake of lean and obese, male and female Osborne-Mendel rats following treadmill exercise were compared. Rats were assigned, separately by sex, to one of three diet groups; Group 1 was fed a low fat (10%) diet throughout the study, Group 2 was fed a high fat (55%) diet for 16 weeks and then switched to the low fat diet 1 week prior to exercise, and Group 3 was fed the high fat diet throughout the study. To control for differences in work output between the leanest and heaviest animals, exercise intensity was adjusted across groups such that all exercised rats had equivalent energy expenditure. After a 3 day training period, the exercise was successively increased over 8 days until a work output of 374.9J was reached. Relative to their respective controls, obese exercised males showed a reduction in body weight but no change in food intake. In contrast, exercised females showed no change in body weight or food intake, regardless of dietary condition.     

Sex chromosome mosaicism in couples undergoing intracytoplasmic sperm injection

BACKGROUND: Several studies have shown an increased frequency of constitutional chromosome aberrations in male and female partners of couples examined prior to ICSI. We conducted a cohort study to determine whether there was an increase in numerical sex chromosome mosaicism among couples undergoing ICSI compared with fertile couples. METHODS: Cytogenetic investigations were performed in 228 females and 208 males seen for ICSI between January 1997 and March 2001. They were matched to control females and males. RESULTS: Sex chromosome loss or gain was observed in at least one cell from 24.1% of ICSI women in comparison with 22% of controls (not significant). A significant difference between these two groups was found when X chromosome loss in at least two cells was considered, 9.6% for ICSI females versus 4.8% for controls (P = 0.01). No significant difference was observed between male groups concerning loss or gain of the X or Y chromosome. CONCLUSION: Our results support previously published studies indicating that the loss of an X chromosome in a single cell in females undergoing ICSI is probably an artefact. However, they suggest that a woman could have true sex chromosome mosaicism when two 45,X0 cells are found.     

Identification of stimuli that mediate experience-dependent modification of homosexual courtship inDrosophila melanogaster

A naive, sexually matureD. melanogaster male tested with a young, sexually immature male will perform vigorous courtship, but the mature male will perform much less courtship if he is subsequently tested with a second young male. This phenomenon is called experience-dependent courtship modification (EDCM). We have shown that exposure to either or both of the two courtship-stimulating pheromones that immature males synthesize is sufficient to induce EDCM.     

Central precocious puberty and abnormal chromosomal patterns

Central precocious puberty (PP) can be caused by chromosomal aberrations. We report three patients presenting with central PP in whom karyotype analysis demonstrated abnormal chromosomal patterns. The first patient was affected by the triple-X syndrome, commonly characterized by premature ovarian failure. The second patient, a girl with inv dup(15)(pter→q12::q12→pter), had a chromosomal aberration involving an imprinted region of the human genome, whose deletion is commonly associated with Prader-Willi syndrome (PWS) and hypogonadotrophic hypogonadism. The third patient was a boy carrying a rare chromosome abnormality, the duplication of chromosome 9 (q22→qter). All patients had mental retardation, which was mild in patient 1, moderate in patient 2, and severe in case 3. They underwent treatment with luteinizing hormone releasing hormone (LHRH) analogs, which were able to stop the progression of the sexual development. We confirm that chromosomal aberrations are an important cause of central PP, and that karyotype analysis in patients with PP and mental retardation, even if mild, is necessary because chromosomal abnormalities can be present.     

Prediction of resting cardiovascular functioning in youth with family histories of essential hypertension: A 5-year follow-up

Two hundred forty-six children (96 Whites, of whom 51 were mates; 150 African- Americans, of whom 69 were males) with a familial history of essential hypertension (EH) were re-evaluated 5 years after an initial evaluation. During the initial visit, anthropometric, demographic, and resting cardiovascular (CV) parameters (designated initial baseline levels) were assessed. These CV parameters (systolic and diastolic blood pressure [BP], heart rate, cardiac output index [CI], and total peripheral resistance index [TPRI]) were also measured during postural challenge, a video game challenge, and a cold pressor task. At follow-up, resting CV parameters were again evaluated, and designated as follow-up resting levels. Moderate temporal stability (r range = .43-.56) was observed for all resting CV parameters. Mean stress responses for each CV parameter for all 3 stressors during the initial visit were positively related to the respective CV follow-up resting level. BP stress responses to postural change and video game challenge were found to be significant independent predictors of future resting BP after controlling for standard EH risk factors. Follow-up resting CI was not predicted by any stress responses, whereas follow-up resting TPRI was predicted by TPRI responses to the video game after controlling for standard EH risk Factors. These results contrast with those from an earlier 1-year follow-up. where stress responses for neither CI nor TPRI predicted follow-up resting levels. It appears that, as children get older. TPRI stress responses play a stronger role in vasoconstrictive function. This research was supported by National Institutes of Health Grant HL41781.     

Autosome and Sex Chromosome Diversity Among the African Pygmy Mice, Subgenus Nannomys (Murinae; Mus)

The African pygmy mice, subgenus Nannomys, constitute the most speciose lineage of the genus Mus with 19 recognized species. Although morphologically very similar, they exhibit considerable chromosomal diversity which is here confirmed and extended by the G-banding analysis of 65 mice from West and South Africa. On the basis of their karyotype and distribution area, the specimens were assigned to at least five species. Extensive differentiation both within and between species was observed that involved almost exclusively Robertsonian translocations, 23 of which are newly described. Two of the rearrangements were sex chromosome-autosome translocations, associated in some cases with partial deletions of the X or Y chromosomes. Several authors have predicted that the highly deleterious effect of this rearrangement would be reduced if the sex and autosomal segments were insulated by a block of centromeric heterochromatin. The C-banding analyses performed showed that among the species carrying X-autosome translocations, one followed the expected pattern, while the other did not. In this case, functional isolation of the sex and autosome compartments must involve other repetitive sequences or genomic traits that require further molecular characterization. Such studies will provide insight into the causes and consequences of the high diversity of sex chromosome rearrangements in this subgenus.     

The effects of age and strain on aggression in male rats

Aggressive behaviors were compared for male Fischer-344 and Long-Evans rats formed into mixed-sex colonies at 100, 200, or 300 days of age. Within each strain, male aggression did not differ across these ages, nor did it differ for an additional group of 600-day old Long-Evans males: both the form and the incidence of specific aggressive and defensive behaviors remained relatively constant over an age range representing nearly the entire normal life span for this species. However, Fischer-344 males at all ages were reliably lower in aggression than the Long-Evans rats. The specific aggression components seen in the Fischer-344 rats tended to be nondamaging, resembling “play fighting” more than the tissue damaging attack behaviors typical of other strains. Despite the frequent use of this strain in gerontological research, such low levels of aggressiveness counterindicate their use in research in aging and aggression.