Nest density and distribution of subterranean ants in an evergreen broadleaf forest in Japan with special reference to Amblyopone silvestrii

The density and distributions of nests of the subterranean ants were studied by excavation of thirty 1‐m² quadrats in an evergreen broadleaf forest in central Japan. A total of 20 ant species were collected and the densities of Amblyopone silvestrii and Paratrechina flavipes were highest (both 0.83 nests/m²). The distribution patterns were analyzed by the Standardized Morisita Index (I_p) for the five species that had mean densities of more than 0.5 nests/m². Of them, A. silvestrii and Hypoponera sauteri showed random distributions, while nests of Paratrechina flavipes were significantly overdispersed and those of Carebara yamatonis and Myrmecina nipponica were weakly clumped. These distributional patterns were discussed in connection with the ecology of the ants. In particular, the social organization of A. silvestrii was investigated based on the distributional pattern and the composition of collected colonies.     

Changes during Development in the Activities and Intracellular Locations of Glycerol Kinase and Hexokinase in Rat Brain and Liver

The changes in activities and intracellular locations of glycerol kinase in rat brain and liver during development were compared. Glycerol kinase activity was consistently much higher in the liver than in the brain from just before the birth to the adult stage. Most of the activity was bound to mitochondria in the brain, but the intracellular distribution of the activity in the liver changed during development, the amount of activity bound to mitochondria being high just after birth and then decreasing gradually. These changes of glycerol kinase during development were compared with those of hexokinase, and the significance of the changes in the two enzymes is discussed in relation to dietary changes during development.     

Analysis of brood development in the ant Amblyopone silvestrii, with special reference to colony bionomics

There are five larval instars in the temperate, subterranean ponerine ant, Amblyopone silvestrii (Wheeler). An examination of the seasonal developmental patterns of immatures collected from more than 100 colonies collected in the field revealed that most or all of the newly hatched individuals overwintered as second to fifth instar larvae and emerged as adults in the next summer. The fifth instar larvae were most abundant in the colony's larval population all year round. The number of eggs present in the nest diminished temporarily in midsummer, although queens collected during this period maintained fully developed ovaries with mature oocytes. When the larvae matured, they were usually moved to temporary nests away from the nest area of the colony and finished pupation and eclosion there, while accompanied by a small number of workers. Pupation of sexuals occurred in the more distant cocoon chambers compared with pupation of workers.     

Phylogeny of Regulatory Regions of Vertebrate Tyrosinase Genes

Highly homologous DNA elements were found to be shared by the upstream regions of the mouse tyrosinase and tyrosinase related protein (TRP-1) genes. Several nuclear proteins were shown to bind to both of these upstream regions. Shared homologous DNA elements were also found in the 5’ flanking sequences of Japanese quail and snapping turtle tyrosinase genes. Shared homologous nucleotide sequences were found to be scattered like an archipelago in the 5’ upstream regions of mouse and human tyrosinase genes. Comparisons between Japanese quail and snapping turtle tyrosinase genes gave similar results. On the contrary, mammalian (mouse and human) and nonmammalian (quail and snapping turtle) tyrosinase genes did not show significant homology in their 5’ upstream regions. In contrast, coding sequences in the first exons of vertebrate tyrosinase genes and their deduced amino acid sequences were found to be highly conserved except for their putative leader sequence-coding regions.     

Changes in Surface Morphology of Myogenic Cells during the Cell Cycle, Fusion and Myotube Formation

The surface morphology of chick myogenic cells during development in cell culture was examined by scanning electron microscopy. Myoblasts at the G₁ and S phases of the cell cycle had a relatively smooth surface. In late G₂ and mitosis, they had many microvilli and some blebs on their surfaces. Ca²⁺-deficient fusion-arrested myoblasts had a relatively smooth surface. When the cells underwent cell fusion, many microvilli, small spherical protrusions, and some blebs appeared on their surface. In newly formed myotubes, the surface over the nucleus was smooth whereas that over perinuclear regions had many flat excrescences and other surface protrusions. This mosaic appearance of the surface was less prominent in striated myotubes. Scanning electron microscopy combined with fluorescence microscopy using rhodamine-labeled erabutoxin b revealed that sites of accumulation of acetylcholine receptor had a smooth surface. These results suggest that changes in surface structure occur in association with the cell cycle, fusion and subsequent development of myotubes.