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31.
Immature rats (aged 28 days) were injected with 4, 20, or 40 IU pregnant mare serum gonadotropin (PMSG) and sacrificed every 6 or 12 hr. Control rats (4 IU) ovulated between 60 and 72 hr, whereas rats given superovulatory doses of PMSG (20 and 40 IU) ovulated between 24 and 72 hr. The oocyte count from the superovulated rats increased slightly between 24 and 36 hr and markedly between 48 and 72 hr. Degenerated oocytes were recovered 48 and 36 hr after administration of 20 and 40 IU PMSG, respectively. Thereafter, the proportion of degenerated oocytes was dose dependent and reached a maximum at 72 (30.9%, 20 IU) and 60 hr (61.0%, 40 IU). 17β-estradiol content of the superovulated ovaries increased significantly (P < 0.01) from 36 hr and was maximal at 60 (20 IU) or 54 hr (40 IU), when compared to the control regimen. Administration of 40 IU PMSG resulted in a biphasic increase of progesterone content with the peaks at 36 and 60 hr. Androgen content of the superovulated ovaries was lower than control levels during the first 36 hr but was significantly (P < 0.01) higher thereafter. The results suggest that these alterations in the steroid response (particularly androgens) from 36 hr onward following superovulation may be responsible for the coincidental occurrence of abnormal oocytes, possibly by disturbing the specific intrafollicular steroid environment essential for complete maturation. In addition, oocyte aging that is due to earlier activation by the exogenous luteinizing hormone activity may be a contributing factor. 相似文献
32.
家兔脑桥臂旁内侧核区微量注射吗啡对中缝大核区单位放电的影响 总被引:1,自引:1,他引:0
实验在62只家兔上进行。结果观察到,中缝大核(NRM)区562个单位中,有118个单位的自发放电频率低,放电比较规则,动作电位时程长,易被微电泳5-羟色胺所阻遏,称为A 组单位。其余444个单位的自发放电频率高,动作电位时程短,称为B 组单位。大多数 B组单位对微电泳5-羟色胺不起反应。脑桥臂旁内侧核(NPBM)区微量注射吗啡(200μg/2μl)或静脉注射吗啡(3mg/kg)后,20个A 组单位中有19个发生兴奋效应,而49个B 组单位中仅有29个发生兴奋效应,而且A组单位发生兴奋的程度也比B组单位的高。这些结果提示,NRM区的A 组单位可能是5-羟色胺神经元,吗啡对这些神经元有相对选择性的兴奋作用。 在另外11只家兔上,应用辣根过氧化物酶(HRP)逆行追踪技术观察到,NPBM 区与NRM 区有纤维联系。 本实验结果提示,静脉注射吗啡所致的呼吸抑制,可能与吗啡作用于 NPBM,通过纤维联系,引起NRM 5-羟色胺神经元兴奋有关。 相似文献
33.
刀豆氨酸对亚洲玉米螟生长发育的影响 总被引:2,自引:0,他引:2
以不同浓度刀豆氨酸注射和饲喂亚洲玉米螟`Ostrinia furnacalis`` 5龄幼虫,影响其以后各虫态的生长发育,有引起畸蛹和畸蛾的明显作用,发育成的雌蛾性腺发育受到抑制,卵管变短,卵细胞数减少。不同交配实验表明对发育成的雄蛾影响更为严重,能使其不育。供试幼虫48小时后取血样,表明血淋巴蛋白质区带与对照组不同,认为刀豆氨酸对亚洲玉米螟的上述作用可能与刀豆氨酸取代精氨酸参入蛋白质的结果有关。 相似文献
34.
35.
Enzymic methods of micro assay have been described for four neutral sugars commonly present in glycoproteins and glycolipids. These assays can be applied to glycoprotein hydrolyzates without prior purification of individual sugars.d-Mannose is assayed by first phosphorylating the sugar in the presence of hexokinase and then measuring the formation of ADP by the use of pyruvate kinase and lactic dehydrogenase. This assay is not specific for d-mannose since both d-glucose and d-glucosamine can be phosphorylated by hexokinase. It is possible to remove d-glucosamine prior to hexokinase treatment by passage through a Dowex 50-X8 (H+) column. The effect of d-glucose in the sample can be corrected for by measuring d-glucose with d-glucose-6-phosphate dehydrogenase, an assay which is highly specific for d-glucose.d-Galactose and l-fucose are measured by their respective dehydrogenases. Neither of these dehydrogenases is affected by sugars commonly found in glycoproteins or glycolipids, nor by the presence of a partial acid hydrolyzate of bovine serum albumin. The methods described enable detection of 0.025 μmole of d-mannose, d-glucose, d-galactose, or l-fucose in a glycoprotein digest. The methods can theoretically be made even more sensitive by the use of fluorometric techniques. 相似文献
36.
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38.
中国拟盘多毛孢属真菌的七个新组合 总被引:4,自引:4,他引:0
作者按照Steyaert(1949)和Sutton(1980)的分类观点,对1987—1988年从我国广西、江西、浙江等地采集的Pestalotiopsis属真菌进行了研究,确认了拟盘多毛孢属真菌的7个新组合种,即Pestalotiopsis carveri(Guba)comb nov.,Pestalotiopsis elasticae(Koord.)comb.nov.,Pestalotiopsis langloisii(Guba)comb.nov.,Pestalotiopsis oleandri(Guba)comb.nov.,Pestalotiopsis sinensis(shen)comb.nov.,Pestalotiopsis sydowiana(Bres.)comb.nov.和Pestalotiopsis zahlbruckneriana(Bres.)comb.nov. 相似文献
39.
Guanylyl cyclase is a heat-stable enterotoxin receptor. 总被引:50,自引:0,他引:50
Plasma membrane forms of guanylyl cyclase have been shown to function as natriuretic peptide receptors. We describe a new clone (GC-C) encoding a guanylyl cyclase receptor for heat-stable enterotoxin. GC-C encodes a protein containing an extracellular amino acid sequence divergent from that of previously cloned guanylyl cyclases; however, the protein retains the intracellular protein kinase-like and cyclase catalytic domains. Expression of GC-C in COS-7 cells results in high guanylyl cyclase activity. In addition, heat-stable enterotoxin from E. coli, but not natriuretic peptides, causes marked elevations of cyclic GMP and is specifically bound by cells transfected with GC-C. The enterotoxin fails to elevate cyclic GMP in nontransfected cells or in cells transfected with the natriuretic peptide/guanylyl cyclase receptors. These results show that a heat-stable enterotoxin receptor responsible for acute diarrhea is a plasma membrane form of guanylyl cyclase. 相似文献
40.
鲫鱼视网膜谷氨酸受体和GABA受体在爪蟾卵母细胞中的表达 总被引:1,自引:1,他引:0
我们以两栖类卵母细胞为功能表达系统,通过注射鲫鱼(Carassiuscarassius)视网膜mRNA,利用电压箝及药物灌流手段,系统地研究了鲫鱼视网膜内氨基酸受体的类型和特征,结果如下:(1)Glu受体:KA可以诱发明显的去极化电流,而且Diazoxide能增强KA诱导的反应,这提示鲫鱼视网膜内某些Clu受体是AMPA选择性亚型(AMPA-preferringsubtype)。(2)CABA受体:GABA能诱发一个快速、光滑的内向电流,绝大部分对GABA的反应可被bicuculline所压抑,而GABA_B受体的激动剂baclofen则无任何作用,这提示,鲫鱼视网膜内大部分是GABA_A受体。 相似文献