No abstract

Male and female aggression at different reproductive stages was investigated in pairs of wild mice. Fourteen pairs of laboratory-outbred wild mice were established, each pair living in a multiple set of cages, connected by runaways. Intruder tests were carried out at different stages of the reproductive cycle, i.e. 48 h after introduction, during pregnancy and lactation. In these stages, a female, a male and two pups were consecutively introduced in each territory (24 h separating each intrusion). Male residents were highly aggressive towards (and always intolerant of) male but not female intruders. Conversely, resident females preferentially attacked same sex intruders after colony establishment and during pregnancy, but they attacked either sex of intruder when nursing young. Seven out of 14 female intruders were tolerated 48 h after introduction of residents but tolerance of females decreased during pregnancy and lactation. Male and female residents were essentially responsible for the intolerance of same-sex intruders. Both males and females exhibited infanticide, but sex differences in the timing of attack on alien pups were observed. In the 7 colonies where the intruder female was tolerated (since that two females were present) only one female reproduced successfully. This suggests that, as in males, females of this stock compete for the opportunity to reproduce; they can be exclusively territorial or form a dominance hierarchy which probably determines reproductive success. While male competitive aggression appears to be mostly directed to other males, females seem largely responsible of the regulation of the reproductive potential of a deme unit throughout intrasexual aggression (intolerance towards other females), and possibly also inhibition of subordinate reproduction and killing of unrelated pups.

Concentrations of chrysene, benz [a I anthracene, benzo [a I -pyrene, benzo [h lfluoranthene, indeno [1,2,3 -c,d] pyrene, dibenz [ a,h I anthracene, and benzo [g,h,i] perylene were measured in placentas from 200 women from two cities in Ukraine, Kyiv and Dniprodzerzhinsk. The participants had no special exposures and were chosen from among subjects in an ongoing study of reproductive health. All seven of the polycyclic aromatic hydrocarbons (PAHs) were found in all placentas, with the sole exception of benzo [a I pyrene in one placenta. Chrysene was present at the highest concentrations, with median 1.38 ng/g dry weight. Dibenz[a,h]anthracene and benzo[g,h,ilperylene had the lowest concentrations; each had median 0.73 ng/g dry weight. Concentrations in Kyiv were slightly higher than those in Dniprodzerzhinsk, butthe differencewas significantonlyfor dibenz [a,h I anthracene. Dibenz [ a,h] anthracene and benzo[g,h,ijperylene increased significantly with maternal body mass index, but other PAHs showed no such pattern. Placentas from deliveries in autumn or winter had slightly but not significantly higher concentrations. Concentrations were not related to maternal age. There were too few smokers in the sample for meaningful evaluation. No associations were seen between any of the placental PAH concentrations and birth weight of the infant.

The central and eastern European countries that composed the former Eastern Bloc have experienced an alarming decline in public health since the dissolution of the Soviet Union. Death rates have increased in most age groups. Life expectancy, especially among males, has decreased in many countries; in Russia, male life expectancy dropped by six years between 1989 and 1994. By 2020, these countries are projected to have smaller increases in life expectancy than any other geographic region. The conditions responsible for the excess mortality are cardiovascular disease, cancer, and injuries among adults. The major factors in the sharp increase are poverty, social disintegration, and crime, overlaid on historically high rates of smoking, alcohol use, and psychosocial stress. Environmental pollution, although common and sometimes severe in the former Eastern Bloc, is another, albeit not the chief, cause of the sharp decline in public health since 1989.

The study reinforces the need to be cautious when using the results from single surveys of retrospective self-reported exposure.