Infertility induced in rats by immunization with synthetic peptide segments of a sperm protein.

Three peptide segments (YAL-198, YAL-201 and YAL-212) corresponding to the extracellular domain of a human sperm protein designated as YWK-II antigen were synthesized as multiple antigen peptide (MAP). Male and female rats were immunized with the YWK-II-MAPs and fertility determined. In a group of 12 female rats immunized with YAL-198, seven animals were infertile and two animals were subfertile. When immunized with YAL-201 and YAL-212, 4 and 2 animals were infertile, respectively. In a group of 15 males immunized with YAL-198, 2 animals were infertile and 6 were subfertile. Two animals immunized with YAL-201 were subfertile. All control male and female rats immunized with bovine serum albumin and adjuvant were fertile. Sera obtained from infertile rats immunized with YAL-198 contained higher titers of antibodies compared to those obtained from fertile animals. The present study shows that immunization with synthetic peptide segments of a sperm protein can effectively reduce fertility.     

Cloning and nucleotide sequence of human liver cDNA encoding for cystathionine gamma-lyase.

We have cloned and sequenced a full-length cDNA (1083 bp) encoding the human liver cystathionine-gamma-lyase enzyme (cystathionase). The human cystathionase sequence presented a substantial deletion of 132 bases (44 amino acids) compared to that reported for rat cystathionase, and of 135 bases (45 amino acids) compared to that reported for yeast cystathionase. After re-alignment for the missing nucleotides, the human cDNA sequence shows significant amino acid homology to that for the rat enzyme (85%) and the yeast enzyme (50%). A search for an undeleted cDNA, by the polymerase chain reaction, yielded a second clone which contained the missing 132 bases. Flanking nucleotides in the latter clone were identical to those in the cDNA clone containing the deletion. The two forms of human cystathionase deduced from the two cDNA clones may be derived from two different genes or may be splice variants.     

PCNA-dependent DNA polymerase delta from rabbit bone marrow.

Proliferating cell nuclear antigen (PCNA) and PCNA-dependent DNA polymerase delta were partially purified and characterized from rabbit bone marrow. Rabbit DNA polymerase delta sediments at 8.2 S upon glycerol density gradient centrifugation. Similar to calf thymus PCNA-dependent DNA polymerase delta, a 125-123-kDa doublet and 48-kDa polypeptides correlate with DNA polymerase activity. Western blotting of rabbit DNA polymerase delta with polyclonal antibody to calf thymus PCNA-dependent DNA polymerase delta gives the same results as calf thymus delta; the 125-123-kDa doublet is recognized. PCNA-dependent DNA polymerase delta is resistant to inhibition by dideoxynucleotides and is relatively insensitive to inhibition by N2-[p-(n-butyl)phenyl]dGTP. A 3'-->5' exonuclease copurifies with the DNA polymerase. The processivity of DNA polymerase delta alone is very low but greatly increases with the addition of PCNA from rabbit bone marrow or calf thymus. Comparative studies of the original DNA polymerase delta from rabbit bone marrow demonstrate a lack of recognition by antibodies to calf thymus delta and a high degree of processivity in the absence of PCNA. Additionally, the originally described DNA polymerase delta is a single polypeptide of 122 kDa. These features would recategorize the original delta to the epsilon category by recently proposed convention. PCNA-dependent DNA polymerase delta is a relatively minor component of rabbit bone marrow compared to DNA polymerase alpha and PCNA-independent DNA polymerase delta (epsilon), the relative proportions being alpha, 60%; delta, 7%; and epsilon, 30%.     

One-electron reduction of chromate by NADPH-dependent glutathione reductase

Electron spin resonance (ESR) measurements provide evidence for the formation of Cr(V) intermediates in the enzymatic reduction of Cr(VI) by glutathione reductase (GSSG-R) in the presence of NADPH, indicating an initial single-electron transfer step in the reduction mechanism. Depending on the pH, at least two different Cr(V) species are generated which are relatively long-lived. In addition, we have detected the hydroxyl (.OH) radical formation during the GSSG-R catalyzed reduction of Cr(VI) by spin trapping, employing 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone (4-POBN) as spin traps. Superoxide dismutase (SOD) causes only a minor effect on the .OH radical and Cr(V) formation, indicating that the O2- is not significantly involved in the reaction mechanism. Catalase enhances the Cr(V) formation and substantially inhibits the .OH radical formation, indicating the involvement of hydrogen peroxide (H2O2) in the reaction mechanism. Addition of H2O2 suppresses Cr(V) and enhances the .OH radical formation. Measurements involving N-ethylmaleimide show that the Cr(V) species, produced enzymatically by the reduction of Cr(VI) by GSSG-R, react with H2O2 to generate .OH radicals, which might participate in the initiation of Cr(VI) carcinogenicity.     

Selective effect of zinc compared to other divalent metals on L-triiodothyronine binding to rat c-erbA alpha and beta proteins

The effects of zinc and other divalent metals on the [125I]T3 binding to rat c-erbA alpha and beta recombinant proteins were assessed. The addition of ZnCl2 caused a reversible and dose-dependent inhibition of [125I]T3 binding to rc-erbA beta proteins with half maximum inhibition occurring at 50-100 microM, but no significant effect on [125I]T3 binding to rc-erbA alpha under the same assay conditions. Scatchard analysis revealed a decrease in [125I]T3 binding capacity to beta protein without marked change in Kd values in presence of zinc. Moreover, significant inhibitions of [125I]T3 binding to both alpha and beta proteins were observed in the presence of 100 microM of either MnCl2, CdCl2 or CuCl2, but not MgCl2. Thus, the selective effect of zinc compared to other divalent metals to inhibit T3 binding to rc-erbA beta, but not alpha, proteins was documented and suggest a possible regulatory role for zinc in modulating the intracellular action of thyroid hormone.     

白百利烟草愈伤组织细胞细胞分裂素结合蛋白的研究

利用BA-Sepharose 4B亲和层析技术丛白百利烟草(Nicotiana tabacum Baibaili)愈伤组织细胞分离提纯了分子量为4400±100道尔顿的细胞分裂素结合蛋白(CB-蛋白)。在细胞表面、核糖体、线粒体、叶绿体和细胞核上以及在细胞液中都有CB-蛋白存在,而核糖体上的CB-蛋白含量量高。探讨了CB-蛋白的功能。     

鸡胚肝乳糖凝集素专一性的研究——SEM-ARG技术的应用

本文利用扫描电镜放射自显影(SEM-ARG)技术研究鸡胚肝凝集素的专一性。该凝集素经乳糖尿素液抽提和离心分离后,再用DE-52纤维素柱和蓝色葡聚糖柱进一步纯化。纯化后的鸡胚肝凝集素用 ¹²⁵Ⅰ标记。以标记的 ¹²⁵Ⅰ-凝集素为探针再标记来自不同组织的细胞。标记的细胞经过放射自显影,用扫描电镜对细胞表面凝集素受体的位点进行直接观察。实验结果表明鸡胚肝凝集素对细胞的凝集作用具有相对的专一性。     

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。