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.     

PHYSIOLOGICAL RESPONSES OF LIGHT-GROWN CUCUMBER HYPOCOTYLS TO HELMINTHOSPOROL AND ITS DERIVATIVES

Helminthosporol, helminthosporic acid and dihydrohelminthosporicacid stimulated hypocotyl elongation of light-grown cucumberseedlings. The relative activities of the three compounds werein the order H₂-H-acid> H-acid> H-ol. The higher the dosage,the longer the promotion of the hypocotyl elongation lasted.The response of the hypocotyl to H-acid depended on the presenceof cotyledons. As the amount of the cotyledon attached to thehypocotyl was reduced, the response decreased. When IAA-oxidase was estimated as IAA metabolized per dry weightof the hypocotyl, there was an inverse relationship betweenIAAoxidase activity and H-ol-induced elongation of the hypocotyl.However, there was no difference between control and H-ol treatedmaterials when IAA metabolized per plant was compared. It isunlikely that the mechanism of H-ol action is closely relatedto IAA-oxidase activity of the plant. (Received April 5, 1967; )     

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.     

Effects of Organic Matter on Solubilities and Crystal Form of Carbonates

The results of a study of the role of organic compounds in theformation of carlxmate crystals in marine biological systemsare reported. In an increasing concentration of certain organiccompounds which complex calcium ions, the proportion of aragonitedecreases and that of calcite increases. In increasing concentrationsof magnesium ions the proportion of aragonite increases andthat of calcite and vaterite decreases. When the influence oforganic compounds is greater or smaller than that of magnesiumions, only calcite or only aragonite is formed, respectively.Organic compounds forming a strong complex with calcium ionscause the formation of magnesium-rich calcite, and with an increasein temperature and the concentration of magnesium ions, themagnesium carbonate content of precipitated magnesian calciteincreases. When the influence of organic compounds is almostequivalent to that of magnesium ions, in increasing or decreasingtemperatures, the proportion of calcite decreases or increases,respectively, and the proportion of aragonite increases or decreases,respectively. The concentration of magnesium ions in the bodyfluids of marine calcareous organisms seems to differ littlefrom that of other organisms, and seems to be similar to thatof sea water. Only the presence of certain organic compoundsbrings about the formation of the carbonate crystals observedin marine biological systems. The very important role of organicmatter in the formation of crystals found in skeletal carbonatesis emphasized.     

Melanoma Antigen and Transforming Gene

We summarize our recent studies on the analysis of melanoma antigen and the melanoma gene recently cloned. The melanoma antigen analyzed by syngeneic monoclonal antibodies is composed of a complex of GM3 ganglioside and protein molecules. The epitope recognized by antimelanoma cytotoxic T lymphocytes seemed to be the combinatorial determinants of GM3 and proteins, whereas the epitope for the suppressor T cells was found to be solely GM3 (NeuAc). The genomic DNA controlling the melanoma antigen was recently isolated and was found to possess transforming activity. The structure of this transforming gene is discussed based on the sequence data of the corresponding cDNA clone.     

Crown Spread Patterns for Five Deciduous Broad-leaved Woody Species: Ecological Significance of the Retention Patterns of Larger Branches

Patterns of crown spread and branch retention of two shade-intolerantspecies (Betula platyphyllaandB. maximowicziana) were comparedwith three more tolerant species (Quercus mongolica,Acer sieboldianumandMagnoliaobovata). Branching height (height of the lowest living branch)rose more rapidly with age for the twoBetulaspecies than forthe shade tolerant species. Branching heights ofA. sieboldianumandM.obovatawere similar, irrespective of tree height and age, andlarger trees tended to produce wider crowns than theBetulaspecieswhen trees of similar height were compared. In all species,the branch basal area (cross-sectional area of a branch at itsbase) and the leaf area per branch generally increased as thebranch position on a stem became lower. Therefore, retaininglarger branches contributed significantly to the support ofa larger leaf area per tree. The number of larger branches (branchbasal area >80 cm²) for bothBetulaspecies was significantlysmaller than that of the shade tolerant species. The branchretention pattern ofBetulaspecies was probably a consequenceof intolerance of the leaves to shade. The decline ofBetulaspecieswith forest succession is likely to occur through their inabilityto retain branches with a large base area in closed forests.Copyright1997 Annals of Botany Company Shade tolerance; crown spread; branch retention; branch size; broad-leaved woody species; leaf area index per tree