Tissue- and Stage-Specific Expression of Sericin Genes in the Middle Silk Gland of Bombyx mori

Sericin gene expression in the middle silk glands during Bombyx mori larval development was analyzed using probes from a genomic DNA clone for 10.5 kb sericin mRNA. The 10.5 kb mRNA, the most abundant in the fifth instar, is not detected in the third feeding, fourth feeding and fourth moulting stages. It becomes detectable at 2 days of the fifth instar, and accumulates rapidly. The second major mRNA in the late fifth instar, a 9.0 kb component having a similar sequence to the 10.5 kb mRNA, becomes detectable only at 6 and 7 days of the instar by use of the repetitious coding sequence probe of the sericin clone. Using the same probe about 20 kb RNAs with a fainter intensity than that of the major mRNAs are detected. They are present extremely faintly in the third and fourth feeding stages, disappear in the fourth moulting stage, and increase in the fifth instar. Two other faint poly(A)⁺ RNA components are detected by a DNA probe containing the 5' end sequence of the sericin clone. One is 4.3 kb, and appears in the third, fourth and fifth feeding stages but not in the fourth moulting stage. The other is 3.0 kb, and it becomes detectable after 1 day of the fifth instar.     

Effects of after-ripening and gibberellic acid on the thermoinduction of seed germination in Solarium melongena

Daily alternating temperatures or a short exposure to low orhigh temperatures were necessary for the germination of eggplantseeds at the initial stage of after-ripening. But requirementsbecame less strict with the progress of after-ripening, andafter 4 to 8 months of afterripening, germination occurred easilyboth at constant (20 and 25) and daily alternating temperatures(30 for 16hrs and then 20 for 8hrs). With further progress in after-ripening, however, daily alternatingtemperatures or a short exposure to low or high temperaturesbecame again indispensable for attaining a high percentage ofgermination. The progress of after-ripening was greatly influencedby the degree of seed ripening, that is, by the period beforethe seeds were sampled from fruits after anthesis (ripening). The effect of GA on the germination of egg plant seeds varieddepending on the concentration of GA, temperature and the degreeof maturity (ripening and after-ripening) of the seeds. (Received March 8, 1968; )     

Synergistic Inhibition of Fructose 1,6-Bisphosphatase by Fructose 2,6-Bisphosphate and Adenosine Monophosphate in Round Spermatids of Rats

The effects of adenosine monophosphate (AMP) and fructose 2, 6-bisphosphate (fruc-2, 6-P₂) on the key-enzyme of gluconeogenesis, fructose 1, 6-bisphosphatase (fruc-P₂ase; D-fructose 1, 6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) in spermatid extract from rat testes were studied. The fruc-P₂ase activity in the spermatids of rats was suppressed by AMP and fruc-2, 6-P₂. The inhibition of fruc-2, 6-P₂ was much stronger at low than at high substrate concentrations, and enhanced synergistically with AMP. The substrate saturation curve was changed by fruc-2, 6-P₂ hyperbolic to sigmoidal. Furthermore, the concentration of AMP that decreased the activity to 50% was much lower in the presence than in the absence of fruc-2, 6-P₂. These results indicate the possibility that gluconeogenesis in spermatids of rats is controlled by AMP and fruc-2, 6-P₂.     

Effects of forest loss and fragmentation on pollen diets and provision mass of the mason bee,Osmia cornifrons,in central Japan

1. Habitat loss and fragmentation potentially affect the performance of bees that forage nectar and pollen of plants in their habitats. In forest landscapes, silvicultural conifer plantations often have reduced and fragmented natural broadleaf forests, which seem to provide more floral resources for bees than do the plantations. 2. This study evaluated the effects of forest characteristics (i.e. elevation, area, edge length, and tree size of natural forests) on pollen diets (plant taxa assemblages of pollen grains in provisions) and total provision mass in oviposited chambers in nests made by a standardised number of Osmia cornifrons bees at 14 sites in a forestry area in central Japan. 3. From April to May, the numbers of nests and chambers per nest increased, and the provision mass per chamber decreased. Main pollen sources were Prunus at higher elevations in April and Wisteria at lower elevations in May, foraging on which increased the numbers of nests and chambers per nest. The provision mass per chamber was smaller at higher elevations in more fragmented natural forests. Decreases in the area of natural forests within the foraging range (400‐m radii) of O. cornifrons increased the utilisation of Rubus pollen and decreased the total provision mass. 4. These findings suggest that the loss and fragmentation of natural broadleaf forests change pollen diets and reduce the provision mass of mason bees, which may reduce the number and size of their offspring.     

Predatory risk increased due to egg‐brooding in Armadillidium vulgare (Isopoda: Oniscidea)

Cost of reproduction is associated with a reduction in subsequent survival or future breeding success. A decrease in survival rate of parents during or after reproduction reduces the probability of their future reproduction. However, few studies have demonstrated such survival costs to parents. Females of Armadillidium vulgare hold their eggs in a marsupium and brood these until the young hatch. Caring for eggs in a marsupium seems to place a large burden on brooding females, and it restricts their predator avoidance behaviour. As such, costs of care may increase the mortality rates of brooding females. To reveal the costs of parental care, we examined the effects of egg brooding on behaviour and predation risk. Egg‐brooding females decreased speed of locomotion and rolling duration, and were killed by predators at a higher rate. Our results indicate that egg brooding in A. vulgare has costs in the form of predation risk.     

COMPARATIVE STUDIES ON GROWTH, RESPIRATION, PHOTOSYNTHESIS AND PIGMENT CONTENT IN RHODOPSEUDOMONAS PALUSTRIS

1. Comparative studies were performed on growth, photosyntheticand respiratory activities, and pigment content in Rhodopseudomonaspalustris.
2. The growth of the organism, as influenced by variousculturalconditions such as light, aerobiosis, anaerobiosisand nutritionalfactors was investigated.
3. The respiratoryactivity of the bacterium was found to be higherin dark-growncells than in cells grown in the light. The photosyntheticactivitydid not significantly depend on the growth conditionsof theculture. Cells of younger cultures were found to be moreactivethan those of older cultures, with respect both to respirationand photosynthesis.
4. The pigment content was found to be higherin the light-growncells than in the dark-grown ones. The ratiophotosyntheticactivity/bacteriochlorophyll was significantlyhigher in thelatter than in the former.
5. Light, as well asvarious nutritional factors, was found toexert a marked accelerationon pigment formation, although ithas not yet been possibleto culture cells completely lackingin photosynthetic pigmentsand accordingly in photosyntheticactivity.

¹ Present address: Division of Dermatology and Urology, TokyoMetropolitan Hiroo Hospital, Tokyo. ² Present address: Department of Biology, Saitama University,Urawa. ³ Present address: Department of Biochemistry, School of Medicine,Yokohama University, Yokohama. ⁴ Present address: Department of Biophysics and Biochemistry,Faculty of Science, University of Tokyo, Tokyo. (Received July 23, 1961; )     

Amphibian chytridiomycosis in Japan: distribution,haplotypes and possible route of entry into Japan

A serious disease of amphibians caused by the chytrid fungus Batrachochytrium dendrobatidis was first found in Japan in December 2006 in imported pet frogs. This was the first report of chytridiomycosis in Asia. To assess the risk of pandemic chytridiomycosis to Japanese frogs, we surveyed the distribution of the fungus among captive and wild frog populations. We established a nested PCR assay that uses two pairs of PCR primers to amplify the internal transcribed spacer (ITS) region of a ribosomal RNA cassette to detect mild fungal infections from as little as 0.001 pg (1 fg) of B. dendrobatidis DNA. We collected swab samples from 265 amphibians sold at pet shops, 294 bred at institutes and 2103 collected at field sites from northern to southwestern Japan. We detected infections in native and exotic species, both in captivity and in the field. Sequencing of PCR products revealed 26 haplotypes of the B. dendrobatidis ITS region. Phylogenetic analysis showed that three of these haplotypes were specific to the Japanese giant salamander (Andrias japonicus) and appeared to have established a commensal relationship with this native amphibian. Many other haplotypes were carried by alien amphibians. The highest genetic diversity of B. dendrobatidis was found in the American bullfrog (Rana catesbeiana). Some strains of B. dendrobatidis appeared to be endemic to Japanese native amphibians, but many alien strains are being introduced into Japan via imported amphibians. To improve chytridiomycosis risk management, we must consider the risk of B. dendrobatidis changing hosts as a result of anthropogenic disturbance of the host‐specific distribution of the fungus.