温度和砷对不同品种水稻幼苗生长和砷吸收的影响

为明确温度和外源砷对水稻生长发育的影响,选取江苏地区常见的8个水稻品种为试验材料,通过添加不同浓度外源砷[0(As0)、0.5(As0.5) 和1 mg?L-1(As1)]和模拟不同温度[白天/夜晚分别为30 ℃/25 ℃（T0）和35 ℃/30 ℃（T1）],在人工气候箱内进行了发芽和苗期培养试验,并分析了8个品种水稻种子萌发、幼苗生长及砷含量状况。结果表明,外源砷对水稻的芽长和活力指数具有抑制作用,与对照（T0As0）相比,T0As1处理使不同品种水稻的芽长和活力指数分别降低13.69%~43.34%和28.14%~52.88%。 而温度对水稻种子萌发的影响与水稻品种有关。在T1处理下,盐两优1618的发芽率、芽长和活力指数均优于其他品种。温度和外源砷的共同作用显著降低了不同品种水稻的芽长（P<0.05）。与T0As0相比,T1As1使水稻芽长显著降低5.66%~43.34%。水稻根长和根系活力显著受到温度和外源砷的单一因素的影响。与T0As0相比,T0As1处理使水稻根系活力降低3.01%~58.21%。温度和外源砷的共同作用抑制了水稻根长和根系活力,其中T1As1使水稻根系活力显著降低53.80%~89.01%。不同品种水稻的苗高和根系活力在相同温度或外源砷处理下具有显著差异（P<0.05）,其中盐两优888的苗高和根系活力均处于较高水平。水稻茎叶砷含量在外源砷处理下显著增加,在增温处理下却降低。与单一的砷处理相比,温度和外源砷的共同作用降低了水稻茎叶的砷含量。综上可知,温度和外源砷影响水稻的生长及砷吸收,但水稻生长状况具有明显的品种间差异,其中盐两优888和盐两优1618在增温和外源砷共存条件下的种子萌发和生长状况优于其他水稻品种。     

Fish oil-induced yellow fat disease in rats. II. Enzyme histochemistry of adipose tissue

Adipose tissue in various stages of fish oil-induced yellow fat disease in the rat had the same acid phosphatase and 5-nucleotidase activity pattern as similar stages of the disorder in mink and pig. A weak acid phosphatase and 5-nucleotidase activity was seen in interstitial lipofuscin-laden macrophages in "stage M" yellow fat disease without fat cell degeneration. Activity of these macrophagic enzymes increased when there was fat cell degeneration ("stage S" and "stage E" yellow fat disease). This different phosphatase activity in the same cell type may result from phagocytosis of substrates with variable digestibility. Macrophages directly surrounding affected fat cells in steatitis areas ("stage S" and "stage E") had strong acid phosphatase and 5-nucleotidase activity. As in the pig, increased 5-nucleotidase activity was found in affected fat cells, which probably indicates plasma membrane damage. Increased nonspecific esterase activity occurred around affected fat cells. Only a small part of this esterase activity originated from inflammatory cells. This indicates that an increase of esterase activity in degenerating adipose tissue may be an endogeneous process in this tissue.     

Erwinia carotovora (Jones) Bergey et al. var. atroseptica (Hellmers et Dowson) Dye. Seed Tuber Infection Versus Symptom Expression in the Field1

Based on the time that symptoms of blackleg become evident in the field and the various ways of inoculation, it is concluded that the spread of symptom expression is due to the depth at which the bacteria penetrate into the interior of the tubers. Moreover, it is demonstrated that it is not the closed lenticels which prevent penetration, but the absence of a waterfilm in the intercellular spaces of the tuber tissue.     

除草剂靶标酮醇酸还原异构酶(KARI)研究进展

酮醇酸还原异构酶(KARI)是植物和微生物体内支链氨基酸生物合成的关键酶之一,可以作为设计除草剂的靶标,通过抑制酶的活性中断支链氨基酸的合成使植物死亡,达到除草目的。文章综述了KARI的催化性质、晶体结构以及作为除草剂靶标的研究现状。