Oxidation and cleavage of 3-aminopyridine adenine dinucleotide phosphate with periodate

Treatment of 3-aminopyridine adenine dinucleotide phosphate with sodium periodate in the neutral pH resulted in oxidation of the ribose linked to 3-aminopyridine and cleavage of the dinucleotide into adenosine- and 3-aminopyridine-containing moieties. Separation of these moieties was afforded by thin-layer chromatography, high-performance liquid chromatography, and fast protein liquid chromatography. From fast atom bombardment mass spectra and nuclear magnetic resonance spectra, the adenosine-containing moiety was identified as 2'-phosphoadenosine 5'-phosphate while the aminopyridine moiety was present in a mixture of the hydrated 3-aminopyridine mononucleotide/nucleoside dialdehyde. Separation of the completely oxidized product by Pharmacia fast protein liquid chromatography gave three major peaks corresponding to 2'-phosphoadenosine 5'-phosphate, 2'-phosphoadenosine 5'-diphosphate and oxidized 3-aminopyridine nucleoside, with minor amount of oxidized 3-aminopyridine mononucleotide. Thus the oxidized 3-aminopyridine adenine dinucleotide phosphate was shown to cleave by two pathways: it may either undergo beta-elimination to give 2'-phosphoadenosine 5'-diphosphate and oxidized 3-aminopyridine nucleoside; or the phosphodiester linkage may be hydrolyzed to give 2'-phosphoadenosine 5'-phosphate and oxidized 3-aminopyridine mononucleotide. The latter compound may further undergo beta-elimination and eventually give oxidized 3-aminopyridine nucleoside. Hydrolysis could be prevented by storing the sample as lyophilized powder, while beta-elimination was diminished by lowering the storage temperature. We found that the lyophilized powder of oxidized 3-aminopyridine adenine dinucleotide phosphate can be stored at -50 degrees C for several months with minimum decomposition.     

豆科根瘤内气体交换和气体扩散模型研究

近年来的研究表明根瘤皮层内存在着可调节的气体扩散屏障,它是由根瘤皮层内的一层细胞及填充在胞间隙的水层构成的,而根瘤是通过改变填充该层胞间隙的水层厚度来调节对气体扩散的阻力。本文概述了关于模拟豆科根瘤内气体交换和气体扩散的数学模型研究,阐明调节根瘤内含类菌体细胞维持低氧分压的有关问题。模型研究使我们获得了对共生固氮根瘤内极为复杂的微生态环境的初步认识,有待于通过改进试验和借助其他理论进一步探索根瘤气体交换和气体扩散的本质。     

我国十省(市)十字花科蔬菜芜菁花叶病毒(TuMV)株系分化研究 Ⅰ.用Green氏方法划分株系

Provvidenti,R.(1980)和Green,S.K.(1985)先后用同一套鉴别寄主谱,研究了美国和我国台湾省的TuMV株系分化情况。本文用Green的方法,对由十省(市)7,982份病样中筛选出的19个TuMV主流分离物,在同一条件下进行了鉴定。结果表明,属于C_1株系的有黑_3分离物;属于C_4株系的有京_2、京_3、冀_2、宁_1(南京)、粤_1和川_1共6个分离物;属于C_5株系的有黑_1、辽_1、京_1、冀_1、沪_1、鲁_1、鲁_2共7个分离物。未检出C_2和C_3株系。黑_2、沪_2、宁_2和秦_1(陕西)共4个性状相近的分离物和冀_3分离物尚不能按Green的标准归类,暂分别定为C_(3-2)和C_6株系。此外,对Green氏方法应用于我国十字花科蔬菜TuMV株系分化研究中存在的问题作了讨论。     

Typing of Verotoxins by DNA Colony Hybridization with Poly- and Oligonucleotide Probes,a Bead-Enzyme-Linked Immunosorbent Assay,and Polymerase Chain Reaction

To identify the type of Verotoxins (VT) produced by Verocytotoxin-producing Escherichia coli (VTEC), a sensitive bead-enzyme-linked immunosorbent assay and polymerase chain reaction with common and specific primers to various VTs (VT1, VT2, VT2vha, VT2vhb, and VT2vp1) were developed. Together with colony hybridization tests with oligo- and polynucleotide probes, these methods were applied to VTEC isolates to type the VT produced. The toxin types of 26 of 37 strains were identified, but the reaction profiles in assays of the remaining 11 strains suggested the existence of new VT2 variants. The application of these identification procedures may be useful as a tool for clinical and epidemiological studies of VTEC infection.     

用光谱技术鉴定植物色素突变体

1983年我国报道了从γ-射线处理的“矮杆齐”大麦中得到了一株黄绿色的突变体1832C[1]。本文用光谱技术对该突变体的光合色素成分进行了鉴定。1　材料和方法　　材料为六棱裸大麦“矮杆齐”和由该品种大麦诱变形成的黄绿色突变体1832C(Mb1832C),以及作为对照的缺失Chlb的突变体大麦Chlorina-f2[2]都于3月初播种于实验田中。　　每个样品取30g新鲜的叶片,先用自来水后用蒸馏水冲洗干净。把洗净的叶片摊放在干净的纱布上吸干表面水分,剪碎,加入100mL预冷的含有0.4mol/L山梨醇、0.1mol/LTris-HCl(pH7.6)的缓冲液,用组织捣碎机先慢速捣碎1…     

Suppression of oxidative damage by Saccharomyces cerevisiae ATX2, which encodes a manganese-trafficking protein that localizes to Golgi-like vesicles.

Oxygen toxicity in Saccharomyces cerevisiae lacking the copper/zinc superoxide dismutase (SOD1) can be suppressed by overexpression of the S. cerevisiae ATX2 gene. Multiple copies of ATX2 were found to reverse the aerobic auxotrophies of sod1(delta) mutants for lysine and methionine and also to enhance the resistance of these yeast strains to paraquat and atmospheric levels of oxygen. ATX2 encodes a novel 34.4-kDa polypeptide with a number of potential membrane-spanning domains. Our studies indicate that Atx2p localizes to the membrane of a vesicular compartment in yeast cells reminiscent of the Golgi apparatus. With indirect immunofluorescence microscopy, Atx2p exhibited a punctate pattern of staining typical of the Golgi apparatus, and upon subcellular fractionation, Atx2p colocalized with a biochemical marker for the yeast Golgi apparatus. We demonstrate here that this vesicle protein normally functions in the homeostasis of manganese ions and that this role in metal metabolism is necessary for the ATX1 suppression of SOD1 deficiency. First, overexpression of ATX2 caused cells to accumulate increased levels of manganese. Second, a deletion in ATX2 caused a decrease in the apparent available level of intracellular manganese and caused sod1(delta) mutants to become dependent upon exogenous manganese for aerobic growth. Third, ATX2 was incapable of suppressing oxidative damage in cells depleted of manganese ions or lacking the plasma membrane transporter for manganese. The effect of ATX2 overexpression on manganese accumulation and oxygen resistance is similar to what we have previously reported for mutations in PMR1, which encodes a manganese-trafficking protein that also resides in a vesicular compartment. Our studies are consistent with a model in which Atx2p and Pmr1p work in opposite directions to control manganese homeostasis.     

Determination of zinc fractions in human blood and seminal plasma by ultrafiltration and atomic absorption spectrophotometry

A simple and reliable method is described which combines ultrafiltration technique with atomic absorption spectrophotometry to determine the Zn fractions in human blood plasma and seminal plasma. Ultrafiltrable, loosely bound, and firmly bound Zn can be measured using this method in the presence or absence of ethylene-diaminetetraacetic acid (EDTA). The YMT membranes for the ultrafiltration must be rinsed thoroughly before use. In contrast to Zn in blood plasma, a large part of Zn in the seminal plasma was found to be ultrafiltrabe. This method can be applied to study the physiologically active part of Zn in body fluids related to various disease states.     

Toxicity to alveolar macrophages in rats following parenteral injection of mercuric chloride

Alveolar macrophages collected by pulmonary lavage from male Fisher-344 rats at intervals (24–72 h) after HgCl₂ injection (1–5 mg/kg, sc) were analyzed by several techniques. Within 24–72 h, the macrophages showed morphological signs of activation (hypertrophy and ruffled plasma membrane). Lipid peroxidation (increased malondialdehyde concentration) was not detected until 48 h. Dose- and time-related effects of HgCl₂ on malondialdehyde concentration and time-related effects of HgCl₂ on malondialdehyde concentration and mercury content of alveolar macrophages were observed 24–72 h postinjection. Diminished cell viability occurred only at 72 h after the highest dosage of HgCl₂. This study demonstrates that the alveolar macrophage was a cellular target for mercury toxicity following parenteral exposure to HgCl₂.     

RFLP mapping of QTLs for yield and related characters in rice (Oryza sativa L.)

Quantitative triat loci (QTLs) for yield and related traits in rice were mapped based on RFLP maps from two indica/indica F₂ populations, Tesanai 2/CB and Waiyin 2/CB. In Tesanai 2/CB, 14 intervals carrying QTLs for eight traits were detected, including 3 for grain weight per plant (GWT), 2 for number of panicles per plant (NP), 2 for number of grains per panicle (NG), 1 for total number of spikelets per panicle (TNS), 1 for spikelet fertility (SF), 3 for 1000-grain weight (TGWT), 1 for spikelet density (SD), and 1 for number of first branches per main panicle. The 3 QTLs for GWT were located on chromosomes 1, 2, and 4, with 1 in each chromosome. The additive effect of the single locus ranged from 2.0 g to 9.1 g. A major gene (np4) for NP was detected on chromosome 4 within the interval of RG143–RG214, about 4cM for RG143, and this locus explained 26.1% of the observed phenotypic variance for NP. The paternal allele of this locus was responsible for reduced panicles per plant (3 panicles per plant). In another population, Waiyin 2/CB, 12 intervals containing QTLs for six of the above-mentioned traits were detected, including 3 for GWT, 2 for each of NP, TNS, TGWT and SD, 1 for SF. Three QTLs for GWT were located on chromosome 1, 4, and 5, respectively. The additive effect of the single locus for GWT ranged from 6.7 g to 8.8 g, while the dominance effect was 1.7–11.5 g. QTL mapping in two populations with a common male parent is compared and discussed.     

Analysis of wild-type and mutant p21WAF-1 gene activities.

The p21WAF-1 gene is positively regulated by the wild-type p53 protein. p21WAF-1 has been shown to interact with several cyclin-dependent kinase complexes and block the activity of G1 cyclin-dependent kinases (cdks). Mutational analysis with the p21WAF-1 gene localized a site, at amino acid residues 21 and 24 in the amino terminus of the protein, for p21WAF-1 binding to cyclins D and E. This region of the protein is conserved (residues 21 to 26) in other p21WAF-1 family members, p27kip-1 and p57kip-2. The same p21WAF-121,24 mutant also fails to bind to cyclin D1-cdk 4 or cyclin E-cdk 2 complexes in vitro, suggesting that amino acid residues 21 and 24 are important for p21WAF-1-cdk-cyclin trimeric complex interactions. The p21WAF-1 wild-type protein will suppress tumor cell growth in culture while p21WAF-1 mutant proteins with defects in residues 21 and 24 fail to suppress tumor cell growth. The overexpression of cyclin D or E in these cells will partially overcome the growth suppression of wild-type p21WAF-1 protein in cells. These results provide evidence that p21WAF-1 acts through cyclin D1-cdk4 and cyclin E-cdk2 complexes in vivo to induce the growth suppression. The p21WAF-1 binding sites for cyclins (residues 21 to 26), cdk2 (residues 49 to 71), and proliferating-cell nuclear antigen (residues 124 to 164) have all been mapped to discrete sites on the protein.