Regulation by kinetin and abcisic acid of correlative senescence in relation to grain maturation,source-sink relationship and yield of rice (Oryza sativa L.)

When kinetin was applied to the source organ (flag leaf) of rice (Oryza sativa L. cv. Ratna), foliar senescence was delayed and grain yield per plant (as evidenced by grain weight, grain/straw weight ratio and 1,000 grain growth) was increased through the increase of sink activity (increase in dry weight of the grains/plant), duration of sink capacity as well as photosynthetic ability of the glumes (as determined by the chlorophyll content of the glumes of the developing grains). However, application of kinetin to the sink organs (fruits), promoted senescence of the source but increased the yield by increasing the sink capacity and 1,000 grain growth mostly at the earlier stage of reproductive development. Lower sterility percentage was associated with higher grain yield of the plant by kinetin treatments. ABA applied either to the source or the sink promoted leaf senescence and reduced the grain yield by reducing the sink activity, harvest index, sink capacity duration and increasing the sterility percentage. Thousand grain dry weight at harvest did not vary significantly amongst the treatments. It was concluded that nutrient drainage was associated with the correlative influence of fruit on the monocarpic senescence of rice plant and that a competetion for differential allocation of cytokinin and ABA in the source and sink organs initiates this senescence syndrome.     

Dye coupling in the organ of Corti

Summary Dye-coupling in an in vitro preparation of the supporting cells of the guinea-pig organ of Corti was evaluated by use of the fluorescent dyes, Lucifer Yellow, fluorescein and 6 carboxyfluorescein. Despite the presence of good electrical coupling in Hensen cells (coupling ratios >0.6) the spread of Lucifer yellow was inconsistent. Hensen cells are very susceptible to photoinactivation, i.e., cell injury upon illumination of intracellular dye; and this in conjunction with Lucifer Yellow's charge and K+-induced precipitability may account for its variability of spread. Fluorescein and 6 carboxyfluorescein, on the other hand, spread more readily and to a greater extent than Lucifer Yellow, often spreading to cell types other than those of Hensen. Dye spread is rapid, occurring within a few minutes. These results suggest that molecules of metabolic importance also may be shared by the supporting cells of the organ of Corti.     

Titration of the binding sites for the oligomycin-sensitivity conferring protein in beef heart submitochondrial particles

The binding parameters of the oligomycin-sensitivity conferring protein (OSCP) in inside-out particles from beef heart mitochondria have been tested by means of two assays, the oligomycin-sensitive ATP-Pi exchange, and the oligomycin-sensitive ATP hydrolysis. The total number of OSCP binding sites in A particles was equal to 220 pmol/mg particle protein. Each mole of ATPase active site was able to bind 1.1 +/- 0.5 mol OSCP with Kd 1.7 nM.     

Isolation of a brain peptide identical to the intestinal PHI (peptide HI)

The isolation of a brain peptide identical to the intestinal peptide PHI (peptide HI) is described. The peptide was isolated from porcine brain extract using a chemical assay method based on its C-terminal isoleucine amide structure. The complete amino acid sequence of the peptide was found to be: His-Ala-Asp-Gly-Val-Phe-Thr-Ser-Asp-Phe-Ser-Arg-Leu-Leu-Gly-Gln-Leu-Ser-Ala- Lys-Lys-Tyr-Leu-Glu-Ser-Leu-Ile-NH2. This sequence is identical to the intestinal peptide thus demonstrating PHI to be a brain-gut peptide. The role of PHI in the central nervous system as a neurotransmitter or neuromodulator is discussed.     

Activation of phosphorylating vesicles by net transfer of phosphatidyl choline by phospholipid transfer protein

Vesicles formed with phosphatidyl ethanolamine, phosphatidyl choline, cardiolipin, coupling factors and hydrophobic proteins from bovine heart mitochondria catalyzed a rapid³²P_i-ATP exchange. When phosphatidyl choline was deleted during the assembly of the vesicles, little³²P_i-ATP exchange was observed. Exchange activity was induced by incubating such deficient vesicles with phosphatidyl choline liposomes in the presence of a phosphatidyl choline transfer protein isolated from bovine heart. Transfer of [³²P] phosphatidyl choline was demonstrated by isolation of the activated vesicles by sucrose density centrifugation.     

掷孢菌科的研究——Ⅲ.不同掷孢酵母属产掷孢子的能力及担子菌酵母形成特大厚垣孢子的规律

本文以分离自中国的大量掷孢酵母为材料,研究了不同属的掷孢酵母生掷孢子的能力,以及此能力的持久性,发现属间差异很大。此外还报道了142株不同酵母的产厚垣孢子的情况,发现与担子菌有关的4属酵母在接近致死温度时,都会出现特大厚垣孢子如红掷孢酵母(Sporobolomyces),布勒掷孢酵母(Bullera),红酵母(Rhodotorula)与隐球酵母(cryptococcus),而属于子囊菌的酵母属(Saccharomyces)则无此现象,从而对某些接近担子菌的酵母又增加了新的认识。     

不同类群酵母胞壁甘露聚糖核磁共振氢谱的比较研究

运用核磁共振氢谱(PMR谱)~(**)对各类酵母的细胞壁甘露聚糖进行比较研究,在我国尚无报道,其中某些酵母也尚无文献记载。本文结果表明:1.同菌株的胞壁甘露聚糖PMR谱型的重复性很好。2.同种不同株的酿酒酵母(Saccharomyces cerevisiae)的多糖谱型也相同。3.所测的二端芽殖酵母中完全型与不完全型菌株的谱型很相似,如柠檬形克勒克酵母(Kloeckera apiculata)与葡萄有孢汉逊酵母(Hanseniaspora uvarum。4.某些分类系统上来源较杂的子囊菌酵母如单宁管囊酵母(Packysolen tanophilus)、萤光威克酵母(Wickerhamiaflurescens)与高糖固囊酵母(Citeromyces matritensis)则体现了各不相同的谱型。5.二株分自西双版纳的极为相近的类酵母(Saccharomycodes sp.)其多糖的(PMR)谱型与多糖的组分都彼此相同,有助于对它们的适当归类。这一切证明酵母胞壁多糖PMR谱型相似程度的比较是分类上较有意义的性状,有助于探讨亲缘关系,核实完全型与不完全型,也有助于对疑难菌株的分析     

Identification of a new subpopulation of triad junctions isolated from skeletal muscle; Morphological correlations with intact muscle

Summary It has been previously recognized that a number of protocols may cause breakage of the triad junction and separation of the constituent organelles of skeletal muscle. We now describe a fraction of triad junctions which is refractory to the known protocols for disruption. Triads were passed through a French press and the dissociated organelles were separated on a sucrose density gradient, which was assayed for PN200-110, ouabain and ryanodine binding. Ryanodine binding showed a single peak at the density of heavy terminal cisternae. On the other hand, the PN200-110 and ouabain, which are external membrane ligands, bound in two peaks: one at the free transverse tubule region and the other at the light terminal cisternae. Similarly, a two peak pattern of PN200-110 and ouabain binding was observed when triad junctions were broken by the Ca²⁺-dependent protease, calpain, which selectively hydrolyzes the junctional foot protein. The light terminal cisternae vesicles were subjected to three different procedures of junctional breakage: French press, hypertonic salt treatment, and protease digestion using calpain or trypsin. The treated membranes were then centrifuged on density gradients. Only extensive trypsin digestion caused a partial shift of ouabain activity into the free transverse tubule region. These observations suggest that the triads are a composite mixture of breakage susceptible, weak, and breakage resistant, strong, triads. Scatchard analysis of PN200-110 suggests that the transverse tubules of strong triads contain a relatively high number of dihydropyridine receptors compared to those of weak triads. Thin section electron microscopic images of the strong triads comparable to those of intact muscle are presented.     

Inhibition of electrical coupling in pairs of murine pancreatic acinar cells by OAG and isolated protein kinase C

Summary Gap junctional coupling was studied in pairs of murine pancreatic acinar cells using the double whole-cell patch-clamp technique. During stable electrical coupling, addition of OAG (1-oleoyl-2-acetyl-sn-glycerol) induced a progressive reduction of the junctional conductance to the detectable limit (3 pS). Prior to complete electrical uncoupling, varius discrete single channel conductances between 20 and 100 pS could be observed. Polymyxin B, a potent inhibitor of the protein kinase C (PKC) system, completely suppressed OAG-stimulated electrical uncoupling. Dialysis of cell pairs with solutions containing PKC. isolated from rat brain, also caused electrical uncoupling. The presence of 0.1mm dibutyryl cyclic AMP and 5mm ATP in the pipette solution, which serves to stabilize the junctional conductance, did not suppress the effects of OAG or isolated PKC. We conclude that an increase of protein kinase C activity leads to the closure of gap junction channels, presumably via a PKC-dependent phosphorylation of the junctional peptide, and that this mechanism is dominant over cAMP-dependent upregulatory effects in the experimental time range (1 hr). A correlation of the observed single channel conductances with the appearance of channel subconductance states or various channel populations is discussed.