Carapace formation of the podocopid ostracode Semicytherura species (Crustacea: Ostracoda)

Details of ostracode carapace structures were examined by SEM and TEM. The podocopine ostracode Semicytherura kazahana has major ridges on the carapace surface and develops its prismatic layer inside the adult carapace. Electron microscopy at the final molt reveals that the major ridges arise from the highly dense formation of pits within the underlying swollen epidermis, and that disappearance of the epidermis in the presumptive area of the prismatic layer occurs after the calcification of the outer lamella cuticle, and just before synthesis of the membranous layer. These facts suggest that the formation of the carapace in Semicytherura takes place via a more complex process than that of the other podocopid ostracodes.     

Ultrastructural Studies on Development of the Tail Gland of a Cuttlefish, Sepiella japonica

Hatching glands in embryos of teleosts and amphibians have been reported to be indispensable for hatching of the embryos. The cephalopod has capsuled eggs, so we expected to find some exocrine organ in the embryos that functioned as a hatching gland. The tail gland (Hoyle's organ) has been suspected to be a hatching gland in the cephalopod, and therefore we examined it during the course of development of cuttlefish embryos. Cells in the tail gland appeared similar to the hatching gland cells (HGCs) of teleosts and amphibians, and contained a number of secretion granules that also resembled the hatching enzyme granules (HEGs) in HGCs of teleosts and amphibians in size, electron density and distribution in the cells. However, a few of these granules were discharged one after another from an early stages, whereas most of them were retained up to the stage just before hatching, and then discharged all at once. The former process of trickling discharge was similar to that in amphibians and the latter process of abrupt discharge resembled that in teleosts.     

Identification of rice root proteins regulated by gibberellin using proteome analysis

Gibberellin (GA) promoted rice (Oryza sativa L.) root elongation in a concentration-dependent manner with roots grown in 0.1 µm GA₃ being 13.8% longer than controls. On the other hand, the roots of Tan-ginbozu, a semi-dwarf cultivar were 69.8% shorter in comparison with Nipponbare, a normal cultivar. Treatments with 10 µm uniconazole-P and 10 µm abscisic acid (ABA) caused decreases in root length in Tan-ginbozu by 44.6 and 79.2%, respectively. To investigate how GA influences rice root growth, proteome analysis techniques were applied. Extracted proteins were separated by two-dimensional polyacrylamide gel electrophoresis and analysed using an automated protein sequencer and mass spectrometer. Sixteen proteins show differences in accumulation levels as a result of treatment with GA₃, uniconazole-P and ABA treatment and/or the difference between the semi-dwarf cultivar, Tan-ginbozu, and normal cultivars. Among these proteins, fructose-bisphosphate aldolase (EC 4.1.2.13) increased in roots treated with GA₃, occurred in low levels in Tan-ginbozu roots, and decreased in roots treated with uniconazole-P or ABA. Moreover, roots from seedlings grown in 100 µm glucose were 9.1% longer than controls. These results indicate that increases in fructose-bisphosphate aldolase activity stimulate the glycolytic pathway and may play an important role in the GA-induced growth of roots.     

Further Evidence for the Presence of a Circadian Clock in the Prothoracic Glands of the Saturniid Moth Samia cynthia ricini: Decapitated Larvae Can Respond to Light-Dark Changes

A small peak of haemolymph ecdysteroid titre precedes the gut purge that characterizes larval-prepupal transition of the saturniid moth Samia cynthia ricini. This peak shifts its phase in parallel with the phase shifts of gut purge according to the changes in light-dark conditions preceding gut purge. Decapitated larvae responded to these light-dark changes as intact larvae did, as assessed by the phase shifts of the haemolymph ecdysteroid peak. This indicates that the brain-centred PTTH clock is not prerequisite for realization of the circadian-clock-controlled timing in the initiation of prepupal development, and supports indirectly our previous notion that the prothoracic glands of Samia possess a circadian clock dictating gut purge timing.     

Light Microscopic Observations of Infraciliature and Morphogenesis in Six Species of Rumen Ostracodinium Ciliates

Infraciliature and morphogenesis of six rumen ciliates, Ostracodinium mammosum, O. munham, O. dilobum, O. rugoloricatum, O. iwawoi, and O. tiete are described from pyridinated silver carbonate-impregnated specimens. These six Ostracodinium have a similar polybrachykinety arrangement, distinct from that of other ophryoscolecid ciliates and intermediate between those of O. gracile and 0. damaliscus. Buccal infraciliature is composed of three polybrachykineties, a kinety loop, and paralabial kineties. Small dorso-adoral polybrachykinety, slender vestibular polybrachykinety, and kinety loop are characteristic. Dorsal infraciliature consists of the dorsal polybrachykinety that extends laterally along the dorsal side of the body. Morphogenesis is different from that of O. gracile, because the right end of ventral primordium extends dorsally to grow into a right primordium without separation.     

Genetic differentiation as a result of adaptation to the phenologies of individual host trees in the galling aphid Kaltenbachiella japonica

Abstract.

• 1 The adaptation of the non-migratory galling aphid Kaltenbachiella japonica (Matsumura) to the budburst phenologies of individual host trees (Ulmus davidiana var. japonica Nakai) was investigated. There was a large variation in budburst time between individual host trees. We tested a hypothesis that aphid populations on respective host trees are genetically differentiated through adaptation to the budburst phenologies of host trees.
• 2 There was significant correlation between the budburst time of eight host trees in two successive years.
• 3 Tree-associated populations differed significantly in egg-hatching time, and the mean hatching time was significantly correlated with the mean budburst time of respective host trees.
• 4 Mating was made between male and female sexuales of the same clone (i.e. self-mating) to obtain selfed eggs. Hatching patterns of selfed eggs showed that there was a substantial amount of genetic variance in hatching time between clones (galls). Nested ANOVA demonstrated that the between-tree component contributed more to the phenotypic variance than the within-tree or within-gall components.
• 5 Reciprocal crosses between males and females of different clones furthermore demonstrated significant differences in hatching time between cross combinations, but no significant differences between the two reciprocals within combinations. This result suggests that there are no maternal effects for the timing of egg hatch and that the differences between selfed lines are attributable to genetic variance.
• 6 The fine-scale adaptation hypothesis was supported by egg-hatching experiments, which further suggest that budburst phenology varying between individual trees is acting as intense selective pressure on the egg-hatching time of associated insects.

     

Influence of Temperature on Glucose Metabolism of Round Spermatids of Rats

Glucose utilization by spermatids was found to be 17.37±0.37 nmoles/hr/10⁶ cells at 34°C and 28.94±1.12nmoles/hr/10⁶ cells at 40°C. A good parallelism was observed between the increased rate of glucose utilization and lactate production at 40°C. There was no significant change in the levels of glycolytic intermediates in the cells, except for marked accumulations of fructose-1, 6-diphosphate, dihydroxyacetone phosphate and glyceraldehyde-3-phosphate in the presence of glucose (1 mM). Glucose oxidation in the citrate cycle by spermatids was higher at 40°C than at 34°C, but was never greater than 2% of the overall rate of glucose utilization. In addition, glucose did not prevent decrease of ATP at either 34 or 40°C. The effects of temperature on the activities of 11 glycolytic enzymes were examined. The activities of aldolase and phosphoglyceromutase were similar between 30 and 34°C, but increased markedly at 40°C. The higher temperature increased the V_max values, without affecting the Kms. The activities of other glycolytic enzymes were similar at the different temperatures. These findings indicate that the increased overall rate of glucose utilization in glycolysis at higher temperature is due to increased Vmax values of aldolase and phosphoglyceromutase.