锌对绵羊睾丸组织细胞和血浆激素水平的影响

研究了锌对公绵羊睾丸支持细胞、间质细胞大小以及血浆睾酮（Ｔ）和促黄体激素（ＬＨ）水平的影响。在公绵羊日粮中添加一定量锌后,试验组与对照组比较,睾丸支持细胞核和质间细胞核（长径×宽径）分别增大２３．３８μｍ２和１２．０５μｍ２（Ｐ＜０．０１）;血浆Ｔ和ＬＨ水平分别升高１５．０１％和３２．６５％（Ｐ＜０．０１）。结果表明,锌对于公绵羊睾丸组织细胞的发育以及ＬＨ和Ｔ的分泌起着重要调节作用。     

氮锌复合作用对白三叶草根瘤超显微结构的影响*

 采用砂培试验和电子显微技术，研究了不同水平氮锌配施对白三叶草根瘤发育和超显微结构的影响。结果表明，随施氮水平增加，根瘤数量、根瘤固氮酶活性、单瘤重量、根瘤细胞内类菌体数量显著下降，类菌体周膜空间增大。与缺锌条件相比，足量供锌显著增加了根瘤数量、单瘤重量、根瘤固氮酶活性、根瘤细胞内类菌体数量和类菌体体积，减小了类菌体周膜空间，类菌体周膜、细胞壁、细胞膜完整性和均匀性增加。与其它处理相比较，低氮和足量供锌处理显著增加了根瘤数量、单瘤重量、根瘤固氮酶活性、根瘤细胞内类菌体数量，显著减小了类菌体周膜空间。     

缺锌对水稻根显微结构和膜透性的影响

缺锌不仅导致水稻根组织分化不良，分生组织细胞膨大、液泡化，而且Ｋ＋和糖的泌出量也明显提高．根的丙二醛含量与Ｋ＋和糖的泌出量呈正相关，表明缺锌条件下膜脂过氧化加剧是膜系统破坏和损伤的原因，锌对根细胞膜结构的稳定性和功能的完整性是不可缺少的．     

Monoclonal antibody to a human germ cell membrane glycoprotein that inhibits fertilization

A monoclonal antibody to an antigen in the human germ cell membrane did not agglutinate or immobilize sperm but inhibited binding and penetration of zona-free hamster ova by human sperm and blocked murine fertilization in vitro. The antibody, of the 2a subclass of immunoglobulin G, was germ cell-specific but not species-specific. It recognized a single antigen of 23 kilodaltons that has been isolated from human germ cells. This fertilization antigen, located on the postacrosome , midpiece, and tail of human sperm, is a glycoprotein of testicular origin associated with some types of human involuntary immunoinfertility .     

Restricted lateral diffusion of PH-20, a PI-anchored sperm membrane protein

The rate of lateral diffusion of integral membrane proteins is constrained in cells, but the constraining factors for most membrane proteins have not been defined. PH-20, a sperm surface protein involved in sperm-egg adhesion, was shown to be anchored in the plasma membrane by attachment to the lipid phosphatidylinositol and to have a diffusion rate that is highly restricted on testicular sperm, being more than a thousand times slower than lipid diffusion. These results support the hypothesis that lateral mobility of a membrane protein can be regulated exclusively by interactions of its ectodomain.     

盐胁迫下不同浓度锌对水稻幼苗生长及细胞膜的影响

[目的]研究在盐胁迫下不同浓度锌对水稻幼苗生长及细胞膜的影响,为水稻的抗盐性研究提供理论依据。[方法]用不同浓度的锌对盐胁迫下的水稻幼苗进行处理,测定相应的形态指标(地上部鲜重)和生理指标(相对外渗率、MDA、SOD、POD和PPO)。[结果]研究结果表明,一定浓度的锌对水稻地上部鲜重有明显的影响,对相对外渗率、MDA、POD和PPO都有一定作用。在1.0 mg/L处理的浓度下,MDA和相对外渗率分别比对照下降17.5%和18.0%,POD活性比对照增加13.4%;在浓度为0.5 mg/L时,SOD活性比对照增加23.3%;在浓度为1.5 mg/L时,PPO活性比对照增加22.9%。[结论]锌浓度为1.0 mg/L时,对细胞膜起到保护作用,能提高水稻对盐害的抗性。     

睾丸支持细胞对体外精子活力的影响

通过建立小鼠睾丸支持细胞与精子共培养的方法,达到体外提高精子活力的目的.利用睾丸组织切片技术,观察并分析支持细胞对生精细胞的作用.从6~7日龄小鼠睾丸中分离睾丸支持细胞,体外培养两天后,形成细胞单层作为滋养层.取小鼠附睾尾内精子,转移到以支持细胞为滋养层的培养液中培养,同时设立对照组.通过精子分析仪观察各组精子的活力,结果显示,以支持细胞为滋养层的精子前向运动百分比为56.1±5.81%,显著高于对照组40.7±2.96% (P<0.05).利用激光共聚焦显微镜观察精子结构,结果显示两组精子形态结构差异不显著,表明支持细胞能够提高体外精子的活力,但不改变精子的形态结构.     

Effect of Zinc Toxicity on Lymphoid Organs in Chickens

The experiment was conducted with the objective of studies on effects of zinc toxicity on lymphoid organs by the methods of experimental pathology and flow cytometry (FCM). 200one-day-old Avian broilers were divided into four groups randomly, and fed on diets as follows: controls (Zn 100mg kg-1)and zinc toxic (Zn 1 500mg kg-1, zinc toxic group Ⅰ; Zn 2 000 mg kg-1, zinc toxic group Ⅱ; Zn 2 500 mg kg-1, zinc toxic group Ⅲ) for seven weeks. The weight and growth index of the thymus, spleen and bursa of Fabricius were reduced in both zinc toxic group Ⅱ and zinc toxic group Ⅲ when compared with those of control group. The G0/G1 phase of the cell cycles of the lymphoid organs was higher, and S, G2+M phases lower in zinc toxic groups Ⅱ and Ⅲ than in control group. Lymphocytes were depleted and degenerate in the lymphoid organs. The reticular cells of the bursa of Fabricius proliferated and the reticular cells of the thymus were also degenerate and necrotic,particularly in zinc toxic groups Ⅱ and Ⅲ. The results demonstrated that more than 1 500 mg kg-1 impaired the progression of lymphocytes from the G0/G1 phase to S phase obviously, inhibited the development of lymphoid organs and caused marked pathological changes in the lymphoid organs. Potential mechanisms underlying these observations are also discussed.     

三氧化二砷诱导大鼠睾丸生精细胞凋亡的研究

[目的]观察不同剂量的三氧化二砷对成年大鼠生精细胞凋亡的影响。[方法]40只健康雄性SD大鼠随机分成4组,分别为0.375、0.750、1.500 mg/kg 3个染毒组和对照组,灌胃法连续给药16周后对各组大鼠进行睾丸脏器系数、精子头计数,并计算每日精子生成量。采用甲基绿—派诺宁染色法和TUNEL法检测大鼠生精细胞凋亡情况。[结果]中剂量组(0.750 mg/kg)和高剂量组(1.500mg/kg)睾丸精子头计数和DSP均低于对照组;与对照组相比,中剂量组和高剂量组生精细胞凋亡指数(AI)均显著升高(P<0.01);生精细胞凋亡指数与每日精子生成量呈负相关(r=-0.563,P<0.01)。[结论]一定剂量的As2O3可通过促进生精细胞凋亡而导致精子生成量的减少,产生生殖毒性。     

锌对小麦幼苗镉胁迫缓解效应的研究

镉胁迫使小麦幼苗膜脂过氧化水平提高,细胞膜透性增大,SOD、POD活性增强。向镉胁迫溶液中加入适量的锌,能使镉毒害引起的膜脂过氧化水平降低,细胞膜透性减小,SOD、POD活性得以恢复。减轻镉对小麦幼苗的毒害作用。     

鼻咽免疫组织化学标记 Ⅱ.神经内分泌性标记

应用神经特异性烯醇化酶和多种激素标记物的免疫组化技术,在鼻咽部发现有两类神经内分泌细胞,即上皮性神经内分泌细胞(存在于披复上皮和陷窝腺体)和小细胞性神经内分泌细胞(弥散分布或灶状聚集于固有膜和陷窝腺体周围)。作者对这两类细胞的来源、生物学特性和病理意义作了探讨。     

Zinc selectively blocks the action of N-methyl-D-aspartate on cortical neurons

Large amounts of zinc are present in synaptic vesicles of mammalian central excitatory boutons and may be released during synaptic activity, but the functional significance of the metal for excitatory neurotransmission is currently unknown. Zinc (10 to 1000 micromolar) was found to have little intrinsic membrane effect on cortical neurons, but invariably produced a zinc concentration-dependent, rapid-onset, reversible, and selective attenuation of the membrane responses to N-methyl-D-aspartate, homocysteate, or quinolinate. In contrast, zinc generally potentiated the membrane responses to quisqualate or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate and often did not affect the response to kainate. Zinc also attenuated N-methyl-D-aspartate receptor-mediated neurotoxicity but not quisqualate or kainate neurotoxicity. The ability of zinc to specifically modulate postsynaptic neuronal responses to excitatory amino acid transmitters, reducing N-methyl-to-aspartate receptor-mediated excitation while often increasing quisqualate receptor-mediated excitation, is proposed to underlie its normal function at central excitatory synapses and furthermore could be relevant to neuronal cell loss in certain disease states.     

SOD对紫外辐射受损的苏云金芽孢杆菌作用的研究

探讨了超氧化物歧化酶 (SOD)等自由基清除剂对苏云金芽孢杆菌紫外辐射的影响。结果表明 ,SOD、绞股蓝皂甙等自由基清除剂能够明显地提高紫外辐射损伤细胞的存活率 ,并且SOD的保护作用表现为防护与恢复两种不同的作用。又通过细胞电泳与琼脂糖凝胶电泳发现紫外辐射后其细胞膜及质粒DNA均受到了明显的损伤 ;SOD对细胞膜损伤有一定的恢复作用 ,而对DNA不表现恢复效应。由此认为 :紫外线对细胞膜及DNA均有损伤 ,SOD恢复作用的主要部位在细胞膜而不是DNA分子。为进一步确定SOD的作用以及利用自由基清除剂制备高效的Bt农药提供了理论基础。     

Structure of the zinc transporter YiiP

YiiP is a membrane transporter that catalyzes Zn2+/H+ exchange across the inner membrane of Escherichia coli. Mammalian homologs of YiiP play critical roles in zinc homeostasis and cell signaling. Here, we report the x-ray structure of YiiP in complex with zinc at 3.8 angstrom resolution. YiiP is a homodimer held together in a parallel orientation through four Zn2+ ions at the interface of the cytoplasmic domains, whereas the two transmembrane domains swing out to yield a Y-shaped structure. In each protomer, the cytoplasmic domain adopts a metallochaperone-like protein fold; the transmembrane domain features a bundle of six transmembrane helices and a tetrahedral Zn2+ binding site located in a cavity that is open to both the membrane outer leaflet and the periplasm.     

Cell cycle-dependent coupling of the calcitonin receptor to different G proteins.

Calcitonin is a calcium regulating peptide hormone with binding sites in kidney and bone as well as in the central nervous system. The mechanisms of signal transduction by calcitonin receptors were studied in a pig kidney cell line where the hormone was found to regulate sodium pumps. Calcitonin receptors activated the cyclic adenosine monophosphate (cAMP) or the protein kinase C (PKC) pathways. The two transduction pathways required guanosine triphosphate (GTP)-binding proteins (G proteins) (the choleratoxin sensitive Gs and the pertussis toxin sensitive Gi, respectively) and led to opposite biological responses. Moreover, selective activation of one or the other pathway was cell cycle-dependent. Therefore, calcitonin may induce different biological responses in target cells depending on their positions in the cell cycle. Such a modulation of ligand-induced responses could be of importance in rapidly growing cell populations such as during embryogenesis, growth, and tumor formation.     

Calcitonin receptors of kidney and bone

Receptors for calcitonin, determined by activation of adenylate cyclase, were found in a distribution among zones of the kidney distinct from that of receptors for parathyroid hormone or vasopressin. Competitive binding studies showed that the receptors for calcitonin are similar in kidney and bone and that their high apparent affinity for salmon calcitonin accounts in part for the high biological potency in vivo of salmon calcitonin.     

Glomerular sialoprotein

The high content of sialic acid in the glomerulus is associated with the cell membrane of epithelial cells lining the basement membrane. Whereas enzyme studies indicate that sialic acid is a determinant of the nephritogenic antigen, the physicochemical properties of this nephritogenic glycoprotein suggest that sialic acid may have an important role in the filtration mechanism.     

水稻和昆虫细胞自噬期间自噬体发生的细胞学机理

【目的】从细胞学角度研究细胞自噬过程中膜结构细胞器的变化及其与自噬体发生的关系。【方法】以基因互作引起细胞调亡现象发生的水稻爪粳杂种F1和天然化合物印楝素、喜树碱、苦参碱诱导凋亡的昆虫细胞Sf9为材料,通过透射电子显微镜和荧光显微镜技术观察细胞自噬凋亡期间自噬体的特征。【结果】水稻杂种F1花粉母细胞在不同发育时期存在不同程度的退化,部分细胞内线粒体形态发生显著变化,形成长哑铃型或线管状,最后两端弯曲形成双层膜结构的细胞器;绒毡层细胞均出现内质网膨大,且逐渐包裹周围其它细胞器,如线粒体,形成双层膜结构的自噬体,最终引发细胞的自噬性凋亡。喜树碱和苦参碱诱发凋亡的细胞胞内线粒体形态发生拉长、弯曲,最后闭合形成包裹其它细胞器的双层膜结构自噬体;印楝素和喜树碱诱发凋亡的细胞胞内核通过分页和出芽的方式形成双层膜结构自噬体。【结论】动植物细胞自噬凋亡过程中,内质网、线粒体和细胞核3种膜结构细胞器均是自噬体膜结构的直接来源,然而3种膜结构细胞器参与自噬体形成的程度和方式因物种、细胞种类以及自噬诱发因素的变化而不同。     

单细胞凝胶电泳技术评价毛鸡骨草的遗传毒性

[目的]应用单细胞凝胶电泳技术评价毛鸡骨草的遗传毒性。[方法]试验分为5组:阳性对照组(环磷酰胺组)、阴性对照组(生理盐水组)、毛鸡骨草高(30 g/kg)、中(20 g/kg)、低(10 g/kg)剂量组,利用单细胞凝胶电泳技术分析小鼠肺、肾、肝、睾丸细胞的尾部DNA率(Tail DNA%)和尾矩(Tail Moment),以观察毛鸡骨草对小鼠DNA的影响。[结果]毛鸡骨草各剂量组对小鼠肺、肾、肝、睾丸细胞的Tail DNA%和Tail Moment影响明显低于阳性对照组,差异极显著(P0.01);毛鸡骨草高剂量组肝细胞Tail DNA%和Tail Moment与阴性对照组相比明显降低,差异极显著(P0.01);其他各剂量组小鼠细胞Tail DNA%和Tail Moment与阴性对照组比,无明显差异(P0.05)。[结论]毛鸡骨草在试验剂量范围内对小鼠肺、肾、肝、睾丸细胞DNA无损伤。     

Regulation of cell fate decision of undifferentiated spermatogonia by GDNF

The molecular control of self-renewal and differentiation of stem cells has remained enigmatic. Transgenic loss-of-function and overexpression models now show that the dosage of glial cell line-derived neurotrophic factor (GDNF), produced by Sertoli cells, regulates cell fate decisions of undifferentiated spermatogonial cells that include the stem cells for spermatogenesis. Gene-targeted mice with one GDNF-null allele show depletion of stem cell reserves, whereas mice overexpressing GDNF show accumulation of undifferentiated spermatogonia. They are unable to respond properly to differentiation signals and undergo apoptosis upon retinoic acid treatment. Nonmetastatic testicular tumors are regularly formed in older GDNF-overexpressing mice. Thus, GDNF contributes to paracrine regulation of spermatogonial self-renewal and differentiation.