CHANGE OF B-TYPE HAEM CONTENT IN RELATION TO PEROXIDASE BIOSYNTHESIS IN INJURED SWEET POTATO ROOTS

The methods of quantitative analysis of b-type haem in plantswere investigated. With an improved method developed was determinedthe haem content in the supernatant, mitochondrial, and microsomalfractions of sweet potato tissue. The activities of peroxidase,catalase, and cytochrome oxidase, as well as the contents ofb-type haem and acid-insoluble nitrogen in the cellular fractionswere determined at different incubation times after cuttingof sweet potato tissue. Peroxidase and catalase increased withtime in each celluler fraction, following a short lag phase.In the mitochondrial fraction, b-type haem, cytochrome oxidase,and acid insoluble nitrogen increased linearly with time. Inthe microsomal and supernatant fraction, b-type haem increasedwith time following a short lag phase. The increase in haemcontent of the supernatant fraction appeared to be associatedwith peroxidase formation. Time course analysis showed that ⁵⁹Fe-incorporation into b-typehaem of the supernatant fraction increased with time and thatincorporation was markedly inhibited by blasticidin S. The incorporationof ⁵⁹Fe into mitochondrial haem did not increase with time andwas not inhibited by blasticidin S. Blasticidin S inhibited⁵⁹Fe-incorporation into microsomal haem. Time course analysisof b-type haem content, ⁵⁹Fe-incorporation into b-type haem,and peroxidase activity suggest that in the injured tissue haemis synthesized from low molecular weight compounds and is incorporatedinto peroxidase as the haem moiety. ¹ This paper constitutes Part 57 of the Phytopathological Chemistryof Sweet Potato with Black Rot. ² Present address: Institute for Plant Virus Research, Chiba.     

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; )     

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.     

How spatangoids produce their traces: relationship between burrowing mechanism and trace structure

Kanazawa, K. 1995 11 30 How spatangoids produce their traces: relationship between burrowing mechanism and trace structure.
Two spatangoid echinoids, Echinocardium cordatum and Lovenia elongata , were allowed to produce their traces in poorly and well-sorted sediments in aquaria. In poorly sorted sediments they formed distinct traces, comparable to fossil traces. Sorting of sediment occurred during transportation by the lateroventral spines and brought about characteristic patterns in grain size at the bottoms of the burrows and in redeposited sediment, which made the traces visible. Differences in the burrowing mechanism between E. cordatum and L. elongata are reflected in their trace structures. E. cordatum formed a laminated backlill structure which resulted from periodic accumulation of excavated sediment behind it, while L. elongata simply pushed excavated sediment by compression to the posterior sides of the test, so that their traces lack a distinct laminated structure and the width of the trace becomes larger than that of the animal. In well-sorted sediment, the echinoids burrowed in the same way as in poorly sorted sediment, but no visible trace was produced other than a drain tube. These observations reasonably explain some characteristic modes of occurrence of fossil spatangoid traces. Their different morphological expressions depend on sediment texture and the uneven lithification of traces. Spatangoids, trace, burrowing mechanism .     

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     

Integrating the proton circuit into photosynthesis: progress and challenges

The formation of trans-thylakoid proton motive force (pmf) is coupled to light-driven electron transfer and both powers the synthesis of ATP and acts as a signal for initiating antenna regulation. This key intermediate has been difficult to study because of its ephemeral and variable qualities. This review covers recent efforts to probe pmf in vivo as well as efforts to address one of the key questions in photosynthesis: How does the photosynthetic machinery achieve sufficient flexibility to meet the energetic and regulatory needs of the plant in a varying environment? It is concluded that pmf plays a central role in these flexibility mechanisms.