Chromosomes of the Indian spiny mouse (Mus platythrix) are studied by the conventional and banding techniques with special reference to their origin. This species has 2n, 26 comprizing 12 acrocentric autosome pairs and acrocentric X and Y chromosomes. The comparison of G- and C-banded chromosomes and the measurement of the chromosome length between the spiny mouse and the house mouse (M. musculus), have made it possible to suggest that 8 autosome pairs (nos. 1 to 8) of the former species have been derived from the tandem fusion of two acrocentric pairs of the latter species. In this case, about 12.8per cent of the centromere and telomere regions of chromosomes seems to be lost from the original karyotype to construct the new formation.
Encysted dry eggs of Artemia sauna are observed under a scanning electron microscope, after irradiation with electrons for 5min. At 18-hr-incubation in 2% NaCl solution at 27°C, the egg shells crack open, and embryos emerge from the shells. At 24- hr-incubation, the embryos hatch out into free-swimming nauplii. Exposure of the eggs shows a linear decrease of hatchability with an increase of irradiation time.
A case of the long arm deletion of a no. 5 chromosome (46, XY, del (5) (q15q31)) is presented. The patient is a fouryear and five-month old boy, and showed slight anemia and leukopenia together with developmental retardation with slight malformations. His mother, father, eldest sister and elder brother are physically and karyotypically normal.
Two-month-old male rats were given daily intraperitoneal injections of 20IU PRL for 6 or 8 days and castrated on the 5th day of the treatment. At 30 hrs after castration the rough endoplasmic reticulum with cisternae arranged in parallel arrays was less numerous and isolated vesicles of the reticulum increased in epithelial cells of the ventral prostates in PRL-treated castrates as compared to vehicle-injected castrates. Morphometric studies revealed that lysosome-like dense bodies were smaller in size and less numerous in PRL-treated rats than in the vehicle-injected controls, although the effects of PRL were no longer detectable 78 hrs after operation. These findings suggest that PRL delays the early progress of involutionary changes in the ventral prostate epithelial cells by inhibiting the lysosomal system.