Male sexual maturation of two Microtus species under laboratory conditions

It is important to know the optimal timing of mating to produce laboratory animals efficiently and to ensure the preservation laboratory strains. To clarify the characteristics of the male sexual maturity of two laboratory Mictorus strains, namely the “Mar” and “MrosA” strains, which are derived from M. arvalis and M. levis, respectively, the testes and epididymes from 4-, 6-, 8- and 10 week-old males were weighed and compared. Although the tissue weights increased gradually with age in the Mar strain, in the MrosA strain, the weight of the testis increased markedly from 4 to weeks of age and that of the epididymis increased from 6 to 8 weeks of age. In addition, the spermatozoa concentrations in the cauda epididymis at 6, 8, and 10 weeks of age in were measured in each strain. The sperm concentration increased in the Mar strain at 8 weeks versus 6 weeks in the MrosA strain. From these results, it is clear that there are differences in the patterns of the increases in testis and epididymis weight and sperm concentration between the two strains. It was suggested that males of the MrosA strain attain sexual maturity earlier than those of the Mar strain

Taxonomic status of Aco strain derived from spiny mice

Spiny mice are useful in regenerative research and as a model for precocial animals. In the present study, we investigated the taxonomic status of the Aco strain, which is derived from spiny mice of an unidentified species. Although this Aco strain has been tentatively considered A. cahirinus species, it was distinguished from this species based on conventional and G-banding chromosomal patterns of this strain. Subsequently, we determined the nucleotide sequence of the mitochondorial gene cytochrome b (Cyb) and constructed a molecular phylogenetic tree. We found that the Aco strain belongs to the same clade as A. dimidiatus. Based on this molecular analysis, we concluded that the Aco strain of spiny mice should be considered A. dimidiatus

Species identification of a laboratory strain belonging to the family Arvicolinae

This study investigated the taxonomic status of a laboratory strain belonging to the family Arvicolinae for which the wild species name is unknown. This vole strain, though considered formerly a Lemming, was distinguishable from any Lemmus species by features of its appearance, skull and molar morphology, and conventional chromosomal pattern. Subsequently, we read the nucleotide sequence of the mitochondrial cytochrome b (Cyb) gene and constructed a molecular phylogenetic tree. We found that this vole strain belongs to the same clade as Microtus guenth

Molecular Identification of t(w5): Vps52 Promotes Pluripotential Cell Differentiation Through Cell-Cell Interactions

After implantation, pluripotent epiblasts are converted to embryonic ectoderm through cell-cell interactions that significantly change the transcriptional and epigenetic networks. An entree to understanding this vital developmental transition is the t(w5) mutation of the mouse t complex. This mutation produces highly specific defects in the embryonic ectoderm before gastrulation, leading to death of the embryonic ectoderm. Using a positional cloning approach, we have now identified the mutated gene, completing a decades-long search. The gene, vacuolar protein sorting 52 (Vps52), is a mouse homolog of yeast VPS52 that is involved in the retrograde trafficking of endosomes. Our data suggest that Vps52 acts in extraembryonic tissues to support the growth and differentiation of embryonic ectoderm via cell-cell interactions. It is also required in the formation of embryonic structures at a later stage of development, revealing hitherto unknown functions of Vps52 in the development of a multicellular organism.NSFCellular and Molecular Biolog