根霉超氧化物歧化酶同工酶类型的鉴别

利用ＫＣＮ、Ｈ_２Ｏ２和ＳＤＳ的选择性反应引起的ＳＯＤ同工酶谱带变化即可鉴别粗抽提液中的ＳＯＤ同工酶类型;用这种方法对五株不同种根霉的鉴别实验表明,它们均不同程度地含有Ｃｕ,Ｚｎ型和Ｍｎ型两种ＳＯＤ,前者约占８０％左右,后者只占２０％左右。用邻苯三酚自氧化法对样品中ＳＯＤ活性测定结果与在同工酶谱上的鉴别结果基本一致。     

Inhibition of rabbit sperm acrosomal enzymes by gossypol

The effect of gossypol on the activities of 10 acrosomal enzymes of the rabbit sperm was evaluated. Acrosin, Azocoll proteinase, neuraminidase, and arylsulfatase were significantly inhibited or completely inactivated by 12–76 μM gossypol. Hyaluronidase, β-glucuronidase, and acid phosphatase were inhibited only at a higher concentration of gossypol (380 μM). Phospholipase C, alkaline phosphatase, and β-N-Acetyl glucosaminidase were not inhibited even at 380 μM gossypol. Gossypol was found to be a noncompetitive inhibitor of arylsulfatase with a Ki of 120 μM. The inhibition was reversible and dose-dependent. As the acrosomal enzymes were more sensitive to the inhibition by gossypol compared to sperm enzymes involved in glycolysis or energy production, these assays may serve as a more reliable indicator for monitoring the occurence of gossypol-induced sterility. © 1995 Wiley-Liss, Inc.     

Analysis of RIM11, a yeast protein kinase that phosphorylates the meiotic activator IME1.

Many yeast genes that are essential for meiosis are expressed only in meiotic cells. Known regulators of early meiotic genes include IME1, which is required for their expression, and SIN3 and UME6, which prevent their expression in nonmeiotic cells. We report here the molecular characterization of the RIM11 gene, which we find is required for expression of several early meiotic genes. A close functional relationship between RIM11 and IME1 is supported by two observations. First, sin3 and ume6 mutations are epistatic to rim11 mutations; prior studies have demonstrated their epistasis to ime1 mutations. Second, overexpression of RIM11 can suppress an ime1 missense mutation (ime1-L321F) but not an ime1 deletion. Sequence analysis indicates that RIM11 specifies a protein kinase related to rat glycogen synthase kinase 3 and the Drosophila shaggy/zw3 gene product. Three partially defective rim11 mutations alter residues involved in ATP binding or catalysis, and a completely defective rim11 mutation alters a tyrosine residue that corresponds to the site of an essential phosphorylation for glycogen synthase kinase 3. Immune complexes containing a hemagglutinin (HA) epitope-tagged RIM11 derivative, HA-RIM11, phosphorylate two proteins, p58 and p60, whose biological function is undetermined. In addition, HA-RIM11 immune complexes phosphorylate a functional IME1 derivative but not the corresponding ime1-L321F derivative. We propose that RIM11 stimulates meiotic gene expression through phosphorylation of IME1.     

Human RNaseP RNA and nucleolar 7-2 RNA share conserved ‘To’ antigen-binding domains

RNase P in both prokaryotes and eukaryotes is a ribonucleoprotein that cleaves tRNA precursors to generate the 5 termini of the mature tRNAs. Many patients with autoimmune diseases produce antibodies against a 40 kDa protein (designatedTo orTh antigen) which is an integral component of eukaryotic RNaseP as well as nucleolar 7-2 RNP which is identical to the mitochondrial RNA processing (MRP) RNP. Interestingly, theTo antigen found in human cells and the C5 protein, the only protein component ofE. coli RNaseP, are antigenically related. In this study, we show that a 56 nucleotide-long sequence, corresponding to nucleotides 20–75 near the 5 end of human RNaseP RNA, is sufficient to bind theTo antigen. We previously showed that the humanTo antigen binds to a short distinct structural domain near the 5 end of human 7-2/MRP RNA. There is no obvious primary sequence homology between theTo antigen binding sites in RNaseP RNA and 7-2/MRP RNA; however, these sequences are capable of assuming a similar secondary structure which corresponds to the recently proposed cage structure for RNaseP RNAs and 7-2/MRP RNA (Forster and Altman (1989) Cell 62: 407–409). These data are supportive of the idea that these two RNAs may have evolved from a common progenitor molecule.     

Specificity and sequence requirements for interactions between various retroviral Gag proteins.

We previously established a genetic assay for retroviral Gag polyprotein multimerization (J. Luban, K. B. Alin, K. L. Bossolt, T. Humaran, and S. P. Goff, J. Virol. 66:5157-5160, 1992). Here we use this assay to demonstrate homomeric interactions between Gag polyproteins encoded by six different retroviruses. Of the Gag polyproteins tested, only those encoded by closely related retroviruses formed heteromultimers. To determine the primary sequence requirements for human immunodeficiency virus type 1 Gag polyprotein multimerization, we studied the effects on multimerization of deletion and linker insertion mutations. Sequences necessary for this process were located between the C-terminal one-third of the capsid domain and the C terminus of the nucleocapsid domain.     

植物细胞离析酶的制备和应用

用 Aspergillus sp．A-19菌经固体发酵研制成一种新的植物细胞离析酶(SeparatasezA—P)。其离析单细胞的酶活力平均为70 767u／g,有效作用的pH在3．0—7．0,温度为20—45℃。发酵培养基配方是麸皮：桔皮粉：(NH₄)₂SO₄(w／w)为100:100:O．63,料水比为1 :2．0,培养适宜条件为25℃、60小时。     

斑须蝽三代卵块的空间分布和田间抽样技术研究

通过田间调查和计算,明确了斑须蝽三代卵块呈聚集分布,且以负二项分布为主。理论抽样数当t＝1．00,D＝0．3时,n＝13．091/＋63．878,如果防治指标定为百株虫卵块12块时,则最大抽样数为173株,序贯抽样的累积虫卵块数量界限为：T0（N）＝0.12N±0．4735。田间随机取样以平行线和Z字形为最佳。     

甜菜碱对呼吸酶的保护效应

以菠菜（Ｓｐｉｎａｃｉａ ｏｌｅｒａｃｅａ Ｌ．）叶片为材料,研究了不同浓度的甜菜碱和ＮａＣｌ对三羧酸循环、末端氧化和光呼吸的组成酶的活性的影响。与电解质ＮａＣｌ不同,高浓度的甜菜碱对这些酶的活性是非抑制性的,并对ＮａＣｌ的抑制作用有一定保护效应。甜菜碱是很好的有机渗透调节剂。这与甜菜碱在细胞质中起渗透调节作用,以及是无机渗透调节剂的配伍溶质的假设是一致的。     

Measles outbreak in 31 schools: risk factors for vaccine failure and evaluation of a selective revaccination strategy.

OBJECTIVE: To examine the risk factors for measles vaccine failure and to evaluate the effectiveness of a selective revaccination strategy during a measles outbreak. DESIGN: Matched case-control study. SETTING: Thirty-one schools in Mississauga, Ont. SUBJECTS: Eighty-seven previously vaccinated school-aged children with measles that met the Advisory Committee on Epidemiology''s clinical case definition for measles. Two previously vaccinated control subjects were randomly selected for each case subject from the same homeroom class. INTERVENTIONS: All susceptible contacts were vaccinated, and contacts who had been vaccinated before Jan. 1, 1980, were revaccinated. When two or more cases occurred in a school all children vaccinated before 1980 were revaccinated. MAIN OUTCOME MEASURES: Risk of measles associated with age at vaccination, time since vaccination, vaccination before 1980 and revaccination. RESULTS: Subjects vaccinated before 12 months of age were at greater risk of measles than those vaccinated later (adjusted odds ratio [OR] 7.7, 95% confidence interval [CI] 1.6 to 38.3; p = 0.01). Those vaccinated between 12 and 14 months of age were at no greater risk than those vaccinated at 15 months or over. Subjects vaccinated before 1980 were at greater risk than those vaccinated after 1980 (adjusted OR 14.5, 95% CI 1.5 to 135.6). Time since vaccination was not a risk factor. Revaccination was effective in reducing the risk of measles in both subjects vaccinated before 1980 and those vaccinated after 1980 (adjusted OR reduced to 0.6 [95% CI 0.1 to 5.3] and 0.3 [95% CI 0.13 to 2.6] respectively). However, only 18 cases were estimated to have been prevented by this strategy. CONCLUSIONS: Adherence to routine measles vaccination for all eligible children is important in ensuring appropriate coverage with a single dose. The selective revaccination strategy''s high labour intensiveness and low measles prevention rate during the outbreak bring into question the effectiveness of such a strategy.