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81.
82.
中国林蛙变态蝌蚪对pH、盐度和碱度的适应性 总被引:4,自引:1,他引:3
在水温16~18℃的野外条件下,采用单因子急性毒性实验法,研究了水环境中pH、盐度和碱度对中国林蛙(Rana chensinensis)变态蝌蚪的毒性效应.结果表明,中国林蛙变态蝌蚪对pH的适应范围为4.3~9.7,最低耐受限3.6,最高耐受限10.7;对盐度的最高耐受限为9.98g·L^-1,适应盐度上限7.14g·L^-1,安全盐度上限1.70g·L^-1;对碱度的最高耐受限为19.96mmol·L^-1,适应碱度上限8.76mmol·L^-1。安全碱度上限2.41mmol·L^-1.野外变态蝌蚪饲养池水体pH应控制在6.5~8.5,盐度控制在2.0g·L^-1以下,碱度不超过4.0mmol·L^-1.中国林蛙变态蝌蚪是一种狭酸碱、低耐盐、低耐碱生物。 相似文献
83.
Liu Jian Yang Xing-Wen Chen Wei-Qiang Tang Jian-Guo 《International journal of peptide research and therapeutics》2002,9(4-5):179-186
Summary Protein engineering techniques were employed to graft the known anticoagulant Arg-Gly-Asp (RGD) motifcontaining sequences
onto the surface of a mutant, inactive insulin framework. To probe the effect of a disulfide bond on the resultant anticoagulant
activity, a native RGD-containing sequence from disintegrin dendroaspin, CFTPRGDMPGPYC, as well as a modified sequence, SFTPRGDMPGPYS
were each examined. The peptide was placed between the C-terminal of the B chain and the N-terminal of the A chain and connected
with B27 and A1 residues of the inactive insulin that lacks the characteristic intramolecular A6–11 disulfide bond within
the A chain. The two RGD-containing insulin genes were over-expressed inE. coli, and purified and designated as RGD-Cys-Ins and RGD-Ser-Ins, respectively. Their amino acid compositions and mass data were
in good agreement with those of expected. The RGD-Cys-Ins showed inhibition of platelet aggregation with an IC50 of 3 μM, while the latter was 3.5-fold less active. Thein vivo assay also indicated that the RGD-Cys-Ins had a higher activity in prolonging the bleeding time in mice than RGD-Ser-Ins.
Both RGD-Cys-Ins and RGD-Ser-Ins retained about 25% of the proinsulin immunoactivity and had almost no insulin receptor binding
activity. The results indicate the necessity for the RGD motif to be conformationally constrained for it to elicit a greater
anticoagulant activity. 相似文献
84.
<正>Liver cirrhosis is the pathologic end stage of multiple liver diseases.The major complications of liver cirrhosis,such as hepatic encephalopathy,spontaneous bacterial peritonitis and esophageal variceal bleeding are characterized by remarkable changes of the gut microbiota,which indicates that enteric dysbiosis might play an important role in the progression of liver cirrhosis[1,2].The human gastrointes- 相似文献
85.
Evaluation of nongenotoxic and genotoxic factors modulating the frequency of micronucleated erythrocytes in the peripheral blood of mice 总被引:3,自引:0,他引:3
The hematological micronucleus test is regarded as an indicator of the clastogenic effect of chemicals and acute cytogenetic damage. The test can be carried out in red blood cells of the bone marrow and of the spleen, as well as in peripheral erythrocytes. We have determined the precise background values of micronucleated red blood cells for the peripheral blood of BALB/c, DBA/2, and NMRI mice. Bleeding, phenylhydrazine-induced hemolysis, and splenectomy generated an increase of micronucleated erythrocytes in the peripheral blood of mice. Our data thus demonstrate that such factors should be taken into consideration when the micronucleus test is used for screening the genotoxic potential of chemicals. Furthermore, the micronucleus-inducing effect of cyclophosphamide was studied in normal and splenectomized mice and, in addition, a comparison of the sensitivity of the micronucleus test was carried out in peripheral blood and bone marrow after cyclophosphamide treatment. Our data demonstrate that the kinetics of micronucleus formation were similar in normal and in splenectomized mice in which the micronucleus levels had returned to normal. The comparison of micronucleus formation in bone marrow and peripheral blood after cyclophosphamide treatment revealed the generation of similar quantities of micronucleated red blood cells in both tissues. The physiological mechanisms of micronucleus formation and removal and the potential role of chemically induced spleen damage during this process are discussed; the usefulness of the peripheral micronucleus test as a simple, rapid, and animal-saving modification of the standard bone marrow test is evaluated.Abbreviations CP
cyclophosphamide
- MN
micronuclei
- MNCE
micronucleated normochromatic erythrocytes
- MNPCE
micronucleated polychromatic erythrocytes
- MNRBC
micronucleated red blood cells
- NCE
normochromatic erythrocytes
- PCE
polychromatic erythrocytes 相似文献
86.
目的:探讨异常黑胆质证肝癌移植模型大鼠Rho/Rock信号通路相关分子的蛋白表达,诠释异常黑胆质肿瘤高发的分子生物学基础。方法:采用足底电击、干寒饲料、铁管制动等多种因素刺激21 d建立异常黑胆质证大鼠模型,在此基础上通过肝内注射walker-256瘤细胞建立异常黑胆质大鼠肝癌移植模型,观察其肝脏组织形态结构变化,并采用Western Blot法检测大鼠肝脏相关蛋白的表达变化。结果:异黑肿瘤组肝脏组织形成明显癌巢,与对照组相比癌旁组织肝索结构紊乱,癌细胞向肝小叶深部迁移;异常黑胆质成熟剂给药组癌细胞崩解、凋亡,胶原纤维增生,癌旁肝索重构。与对照组相比,肿瘤组Cdc42和Rock2蛋白表达均明显增加(P0.05),异黑肿瘤组Cdc42、Rac1、Rock1、Rock2和Myl1蛋白表达明显增加(P0.05);与异黑肿瘤组相比,异常黑胆质成熟剂(ASM)给药组Cdc42、Rac1、Rock1、Rock2和Myl1蛋白表达呈剂量依赖性降低(P0.05),且与对照组无显著差异。结论:异常黑胆质证肝癌移植模型可能与Rho/Rock信号通路分子通过调控肌动蛋白收缩引起的肿瘤细胞侵袭、转移生物学行为等作用有关,异常黑胆质成熟剂可能通过下调Rho/Rock信号通路分子使损伤的组织形态逆转。 相似文献
87.
Omega‐3 fatty acids modulate the lipid profile,membrane architecture,and gene expression of leiomyoma cells 下载免费PDF全文
88.
89.
90.
High-frequency conversion of abnormal peanut somatic embryos 总被引:17,自引:0,他引:17
Peanuts (Arachis hypogaea L.) are widely cultivated as a rich source of protein and oil. Although protocols for the regeneration of peanut via somatic
embryogenesis and organogenesis have been developed, most of them have resulted in low frequencies of plant recovery. In this
report, we describe a protocol for plantlet formation at high frequency from somatic embryos. Morphologically abnormal somatic
embryos germinated and produced roots only in medium devoid of growth regulators. Shoots emerged from the undeveloped plumule
of these rooted embryos in medium containing both 6-benzyladenine (BA) and kinetin (KN), or in medium with thidiazuron (TDZ)
alone. In Murashige and Skoog basal medium supplemented with 8.9 μm BA and 14 μm KN, 86% of the embryos developed shoots. Substitution of BA and KN with 22.7 μm TDZ increased plant recovery from 86% to 92%. Plants grown on TDZ had multiple shoots. Eighty-four percent of these plants
survived in sandy soil and were grown to maturity.
Received: 12 February 1996 / Revision received: 11 July 1996 / Accepted 30 April 1997 相似文献