不同施氮量对甜椒碳、氮营养分配的影响

 通过水培试验，利用 N和”C双示踪技术研究了不同施氮量对甜椒结果期碳、氮营养分配的影响 结果表明：结果前期吸收的 N在低氮(NO3一N 2．5 mol·L～，NH4+一N 0．25 mol·L )营养处理下分配于果实中的比率高于中氮(NO；一N 5．0 mol·L～，NH —N 0．5 mol·L )和高氮(NO；一N 11．0 mol‘L～，NH4+一N 1．0 mol·L )营养处理。氮水平制约着 N在各器官中的分配和再运转，很少影响”C在器官间的分配，但却制约着”C的运转和再分配，表现为中氮营养最有利于 C向果实中的再运转。碳氮营养平衡有利于碳素向生殖器官的运转和积累，这是低氮营养产量前高后低，高氮营养产量前低后高，中氮营养前后期产量均较高的根本原因。     

Suppressive effect of liquid potassium silicate on powdery mildew of strawberry in soil

A soil drench of soluble silicon (liquid potassium silicate) was tested for the control of powdery mildew of strawberry in soil for 2 years in a vinyl house under growers' conditions on two cultivars: very susceptible Toyonoka and slightly susceptible Sachinoka. Soluble silicon suppressed the disease more effectively as a preventive control than as a control to reduce initial incidence. The suppressive effect against this disease was more effective for Toyonoka than for Sachinoka. The control value of soluble potassium silicate was 85.6% for Toyonoka in the first year and 60.2% in the second year, while for Sachinoka it was 58% in the first year and 40.6% in the second year. Strawberry leaf hardness was measured for the control and silicate-treated leaves. Although silicate-treated leaves seemed to be harder than control leaves, leaf hardness did not vary significantly between controls and silicate-treated leaves in either of the 2 years, and the mode of preventive action of liquid potassium silicate remains unknown. A factor other than a physical action may be involved.     

Behavior of four broad-leaved tree species used to revegetate eroded granite hill slopes

Information on primary growth behavior after planting is required for mixed-plantation revegetation using broad-leaved species. To estimate primary growth, especially from the perspective of crown coverage and changing growth rates, we examined the growth and survival of four broad-leaved species that are frequently used in erosion-control plantations in Japan. The species studied were Myrica rubra Sieb. et Zucc., Alnus pendula Matsum., Quercus glauca Thunb., and Q. serrata Thunb. The survival, height, and basal diameter of planted trees were measured over a 4-year period, and crown area was calculated over a 3-year period. We found a negative relationship between relative growth rate (RGR) and survival rate, suggesting that fast growth may be fatal when resources are severely limited. The relative height growth rate (RHGR) of A. pendula was especially high during the early period of the study (1997–1999) and then drastically declined, whereas the opposite tendency was observed in Q. glauca. The results of stem allometry analyses conformed to the specific relationships between height growth and diameter growth of the four species; increases in stem thickness based on height increments were smaller in the pioneer species A. pendula. Between-species differences in coverage per planted tree (mean crown area multiplied by survival rate) were small as a result of the negative relationship between coverage area and survival rate.     

Female-biased mortality rate and sexual size dimorphism of migratory masu salmon, Oncorhynchus masou

Abstract –  We examined whether mortality and growth during the migration phase (the lacustrine phase after smolting) differ between sexes in migratory (lake-run) masu salmon ( Oncorhynchus masou ) in a lacustrine population, northern Hokkaido, Japan. The sex ratio of 1+ smolts was more skewed to females than that of the returning adults in three annual cohorts examined, indicating that females have a higher mortality rate during the migration phase. Although there was no difference in smolt length between sexes, female adults were larger in body length than males of the same age: female-biased sexual size dimorphism (SSD) occurs. We suppose that breeding selection favouring a larger body size for females than for males in this population probably requires that females undertake more intensive foraging behaviour with its greater inherent risks but faster growth rates during the migration phase. It therefore seems to be likely that the selection is the ultimate cause of the female-biased mortality rate and SSD.     

Chromosomes responsible for sensitivity of embryo to abscisic acid and dormancy in wheat

The sensitivity of the embryo to abscisic acid (ABA) has been reported toplay an important role in seed dormancy. Using ditelocentric lines of wheatcv. Chinese Spring (CS, nondormant and ABA insensitive), F₂ seedsbetween monosomic lines of CS and a wheat line Kitakei-1354 (dormant,ABA sensitive) and deletion lines of CS chromosome 4A, germinability ofseeds and embryo-half seeds incubated in water and ABA were examined. The results indicated that the long arm of chromosome 4A carried majorgene(s) for the embryo sensitivity to ABA and dormancy. Chromosome2D might be also involved in the sensitivity to ABA.     

Identification of a novel cytotoxic protein, Cry45Aa, from Bacillus thuringiensis A1470 and its selective cytotoxic activity against various mammalian cell lines

Parasporal inclusion proteins produced by Bacillus thuringiensis strain A1470 exhibit strong cytotoxicity against human leukemic T cells when activated by protease treatment. One of the cytotoxic proteins was separated by anion exchange chromatography and gel filtration chromatography and designated Cry45Aa. Its gene was then expressed in recombinant Escherichia coli, in which the Cry45Aa precursor was accumulated in an inclusion body. It was solubilized in sodium carbonate buffer and processed with proteinase K, and cytotoxic activities of the protein against various mammalian cell lines were evaluated using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide assay. The protein exhibited high cytotoxic activity against CACO-2, Sawano, MOLT-4, TCS, and HL60 cells and moderate activity against U-937 DE-4, PC12, and HepG2 cells. On the other hand, the EC50 values against Jurkat, K562, HeLa, A549, Vero, COS-7, NIH3T3, CHO, and four normal tissue cells (human primary hepatocyte cells, UtSMC, MRC-5, and normal T cells) were >2 microg/mL.     

Cartilage acidic protein-1B (LOTUS), an endogenous Nogo receptor antagonist for axon tract formation

Neural circuitry formation depends on the molecular control of axonal projection during development. By screening with fluorophore-assisted light inactivation in the developing mouse brain, we identified cartilage acidic protein-1B as a key molecule for lateral olfactory tract (LOT) formation and named it LOT usher substance (LOTUS). We further identified Nogo receptor-1 (NgR1) as a LOTUS-binding protein. NgR1 is a receptor of myelin-derived axon growth inhibitors, such as Nogo, which prevent neural regeneration in the adult. LOTUS suppressed Nogo-NgR1 binding and Nogo-induced growth cone collapse. A defasciculated LOT was present in lotus-deficient mice but not in mice lacking both lotus- and ngr1. These findings suggest that endogenous antagonism of NgR1 by LOTUS is crucial for normal LOT formation.