蓝藻原生质球研究的现状及存在问题

在原生质体(球)技术方面,蓝藻也许是一种最为困难的材料了。蓝藻原生质球的研究工作起步不算很晚,但进展不快。直到现在,作为一项可以用于遗传操作的基本技术还没有建立起来。这主要表现在,原生质球的再生问题没有解决;此外,在基本分离制备方面也存在不少问题。而对于植物、真菌、细菌、放线菌和绿藻,这些问题都早已     

青霉素对蓝藻细胞的作用

1967年,Biggins首次报道通过溶菌酶处理获得了有生活力的篇藻(Phormidium luridum)原生质球。此后,虽然许多作者在这方面作了不少工作,但原生质球的再生和融合问题至今没有得到解决。再生和融合与分离制备方法密切相关,因此,     

不同季节银木叶精油化学成分的研究

用毛细管气相色谱-质谱-计算机联用技术、毛细管气相色谱双柱保留指数法和双柱标准品叠加法分析了不同季节银木叶精油化学成分。从分离出来的207—250个色谱峰中,初步鉴定出59个成分,被鉴定成分的总量占精油总组成的94.45—98.92%,其主要成分随采油季节不同而有所不同。     

Mobilization of calcium from intracellular stores as one of the mechanisms underlying the antiopioid effect of cholecystokinin octapeptide.

In enzymatically dissociated brain cells prepared from neonatal rats, KCl produced a significant increase in [Ca2+]i and this increase could be prevented by verapamil or nifedipine, known to block voltage-sensitive calcium channels. The opioid receptor agonists ohmefentanyl (OMF, mu agonist), [D-Pen2,D-Pen5]enkephalin (DPDPE, delta agonist), and 66A-078 (kappa agonist) produced a marked suppression of the Ca2+ influx induced by high K+ depolarization. The suppressive effect of OMF, DPDPE, and 66A-078 on the high K(+)-induced increase in [Ca2+]i was markedly reversed by their respective antagonists beta-funaltrexamine (beta-FNA), ICI174864, and nor-binaltorphimine (nor-BNI). Cholecystokinin octapeptide (CCK-8), at concentrations of 0.3, 3.0, and 30 nM, dose-dependently mobilized Ca2+ from intracellular stores. While CCK-8 30 nM did not affect significantly the increase of [Ca2+]i following high K+, it did reverse the suppression of the high K(+)-induced increase in [Ca2+]i by the mu agonist OMF and the kappa agonist 66A-078, but not that by the delta agonist DPDPE. The results suggested that while opioid ligands suppress [Ca2+]i by blocking voltage-operated Ca2+ influx, the antiopioid effect of CCK-8 seems to be operated via mobilization of Ca2+ from intracellular stores.     

Differentiation of the melanotrophic cells of rat pituitary primordium in organotypic culture in defined medium

Summary Organotypic cultures, in defined medium, of pituitary primordia obtained from 15-day-old rat fetuses were performed in order to study the in vitro differentiation of melanotrophic cells. The morphological and ultrastructural features of the transplants resembled those of the gland developing in vivo. In situ hybridization on semi-thin sections, using a ³⁵S-labelled oligonucleotide probe, revealed pro-opiomelanocortin-mRNA-containing cells on the first day of culture in the anterior lobe and after 2–3 days in the intermediate lobe. Immunoperoxidase labelling of adjacent sections showed that the same cells reacted with antibodies against -melanocyte-stimulating hormone (MSH), ₃ and adrenocorticotropic hormone in both lobes. The pro-opiomelanocortin-mRNA-containing cells formed progressively conspicuous areas in the intermediate lobe, which was almost uniformly labelled after 6 days. In the anterior lobe, these cells remained scattered in small cell groups, and colloidal gold immunolabelling showed the progressive disappearance of MSH labelling from the secretory vesicles in cells exhibiting morphological features of adult corticotrophic cells. Both the MSH content of the explants and MSH release into the culture medium increased with time. Treatment with the dopamine agonist bromocriptine induced a strong dose-dependent decrease in MSH secretion, which was significant after 3 days in culture, indicating that dopamine D₂ receptors are able to regulate hormonal release of melanotrophic cells at early stages. This system constitutes a suitable model for further studies of factors controlling cell differentiation and cellular interactions involved in histogenesis.     

头端延髓腹外侧区注射5—羟色胺对应激性高血粘度...

Experiments were carried out on 62 wistar rats. The hyperviscosity and elevation of blood pressure were induced by hanging and restraining the rats with their four limbs tied on a frame. It was found that microinjection of 5-HT (25 micrograms/10 microliters) into the 4th ventricle of the brain or bilateral microinjection of 5-HT (4 micrograms/0.5 microliters/site) into rostral ventrolateral medulla (rVLM) reduced stress-induced hyperviscosity (p < 0.01) and elevation of blood pressure (p < 0.01). The effect of 5-HT injected into the 4th ventricle or rVLM was blocked by bilateral microinjection of cinanserine (4 micrograms/0.5 microliter/site) into rVLM. These results suggest that microinjection of 5-HT into 4th ventricle and rVLM could reduce stress-induced hyperviscosity and elevation of blood pressure and these effects were probably mediated via 5-HT receptors in the rVLM.     

Age and growth of tarpon,Megalops atlanticus,larvae in the eastern Gulf of Mexico,with notes on relative abundance and probable spawning areas

Synopsis Leptocephali were collected in June 1981 and July 1989 over the continental shelf and slope of the Florida west coast. Tarpon larvae ranged 5.5–24.4 mm standard length (SL) and were the second most abundant leptocephalus species. Sagittae examined with compound microscopes and scanning electron microscopy had increments that were presumed to be formed daily. Increment counts made using the two microscopic techniques were not significantly different. Estimated ages ranged 2–25 days with a growth rate (± standard error) of 0.92 ± 0.04 mm d^–1 The least squares linear regression equation SL = 2.78 + 0.92 (age in days) best described the relationship between estimated age and length. Adult tarpon appear to undergo a substantial spawning migration from inshore areas frequented during spring and summer to offshore spawning grounds. Spawning occurs during May, June, and July, although the spawning season may be of greater duration.     

马铃薯Y病毒外壳蛋白基因的克隆及序列分析

本文报道应用聚合酶链式反应(PCR)技术,在体外扩增马铃薯 Y 病毒外壳蛋白基因及其克隆和序列分析的结果。病毒 RNA 从马铃薯 Y 病毒感染的烟草叶片中提取,用合成的PCR 3引物及 AMV 逆转录酶合成了单链的 cDNA。利用 PCR 技术,经30个循玎的扩增。得到了一特异的0.8kb 片段。克隆后对此片段进行了限制性内切酶物理图谱分析,并测定了其全序列。实验结果证明,我们克隆到的是完整的马铃薯 Y 病毒的外壳蛋白基因。与国外报道的马铃薯 Y 病毒 N 株相比,其核苷酸序列及推测的氨基酸序列的同源率分别为97.8%和97%。将该基因导入马铃薯以期获得抗 Y 病毒马铃薯的工作正在进行。本文还对 PCR 技术用于扩增植物 RNA 病毒的方法以及用基因工程方法培育抗病毒作物新品种的可行性等进行了讨论。     

PVA和PEG预处理对大豆种子在低温吸胀过程中胚根线粒体发育和超微结构的影响

电镜观察发现,大豆种子在刚开始萌发时胚根细胞中未能见到线粒体,线粒体是在种子萌发过程中逐渐出现的,由原质体再分化发育而成。对照胚根细胞内原质体在低温吸张过程中明显膨胀,在回温后胚根细胞中原质体仍不能发育成线粒体,甚至网状膜结构破坏,呈空泡化;经聚乙烯醇(PVA)和聚乙二醇(PEG 6000)预处理的大豆种子在同样条件下线粒体能继续发育,在回温后预处理胚根细胞中线粒体发育良好,具有明显的双层膜和管状嵴的结构。这些结果表明,在低温吸胀过程中原质体能够继续再分化发育成线粒体是提高大豆种子活力和抗冷力的重要原因。     

Structure and sequence of the human α- -iduronidase gene

In humans, a deficiency of the lysosomal hydrolase α- -iduronidase (IDUA; EC 3.2.1.76) results in the lysosomal storage of the glycosaminoglycans heparan sulfate and dermatan sulfate, thereby causing the lysosomal storage disorder mucopolysaccharidosis type I. The gene for IDUA is split into 14 exons spanning approximately 19 kb. We report the sequence of two noncontiguous segments of the IDUA gene, one 1.8-kb segment containing exons 1 and 2 and surrounding sequences and a second segment of 4.5 kb containing the last 12 exons. The potential promoter for IDUA has only GC box type consensus sequences consistent with a housekeeping promoter and is bounded by an Alu repeat sequence. The first two exons of IDUA are separated by an intron of 566 bp, then there is a large intron of approximately 13 kb, and the last 12 exons are clustered within 4.5 kb. No consensus polyadenylation signal was found in the 3′ untranslated region, although two variant polyadenylation signals are proposed.