The assessment of behavioral changes produced by prenatal or early postnatal exposure to potentially noxious agents requires both the designing of ad hoc tests and the adaptation of tests for adult animals to the characteristics of successive developmental stages. The experience in designing tests is still more limited than in the adaptation of tests, but several tests have already proven their...

Sexually naive male mice show robust aggressive behavior toward pups. However, the proportion of male mice exhibiting pup-directed aggression declines after cohabitation with a pregnant female for 2 weeks after mating. Subsequently, on becoming fathers, they show parental behavior toward pups, similar to maternal behavior by mothers. To elucidate the neural mechanisms underlying this behavioral...

Early mortality and pup growth during the perinatal period were investigated in pups of the subantarctic fur seal Arctocephalus tropicalis on Amsterdam Island. Mothers that were shorter in body length and expected to be younger, gave birth earlier in the pupping season, compared with longer/older mothers. Pups born early were often still-born, suggesting that shorter/younger mothers that gave b...

The heat dissipation limit theory suggests that heat generated during metabolism limits energy intake and, thus, reproductive output. Experiments in laboratory strains of mice and rats, and also domestic livestock generally support this theory. Selection for many generations in the laboratory and in livestock has increased litter size or productivity in these animals. To test the wider validity...

During lactation, adult female mice display aggressive responses toward male intruders, triggered by male-derived chemosensory signals. This behavior is not shown pup-sensitized virgin females sharing pup care with dams. The genetic mechanisms underlying the switch from attraction to aggression are unknown. In this work, we investigate differential gene expression in lactating expressing matern...

Male rat sexual development was evaluated after dietary administration of 0, 760, 3800, 11,400 ppm diisononyl phthalate (DiNP) and 7600 ppm dibutyl phthalate (DBP) from gestation day (GD) 12 to postnatal day (PND) 14. Maternal weight was reduced on GD 20, PND 2 and 14 at 11,400 ppm DiNP. Pup weight was reduced on PND 2 and 14 at 11,400 and 3800 ppm DiNP. DBP induced multinucleated germ cells (M...

Rat pups (7-9 days of age) were made cold and hypoxic simultaneously while interscapular temperature, rectal temperature, and ultrasound emission were monitored. These hypoxic pups cooled faster than control pups, which indicates decreased thermogenesis and decreased oxygen consumption, and produced less ultrasound. In a separate experiment, pups deprived of milk for 24 hr cooled faster and als...

The proper functioning of any biological system depends on the coordinated activity of its components. Regulation at the genetic level is, in many cases, effective in determining the cellular levels of system components. However, in cases where regulation at the genetic level is insufficient for attaining harmonic system function, posttranslational regulatory mechanisms are often used. Here, we...

The goal of this research was to determine when harbor seal pup vocalizations become sufficiently distinctive to allow individual recognition. A total of 4593 calls were analyzed from 15 captive pups. Nineteen were harsh, broadband, staccato calls used in an aggressive context. The rest were tonal "mother attraction calls," having an inverted "v"- or "u"-shaped spectrogram with harmonics and a ...