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星型胶质细胞虽然没有动作电位,但是可以表达多种受体和离子通道,并且以细胞内钙波传递的方式来响应各类刺激。星型胶质细胞同样可以释放多种信号分子来介导细胞间的通讯。尤为特别的是,星型胶质细胞的钙波传播和突触功能的反馈调节都需要其释放ATP才得以完成。然而,星型胶质细胞释放ATP的途径和机理还有待研究。尽管人们已经在星型胶质细胞中发现了小囊泡和大致密核心囊泡的标记物,可是用以胞吐的囊泡究竟是什么还并不清楚。作者等近期的研究成果表明,FM染料——一种被成功应用于研究神经元和其他分泌型细胞囊泡循环的染料,可以特异地标记星型胶质细胞的溶酶体,并依不同程度的刺激表现出两种不同模式的钙离子依赖性胞吐:在较低强度刺激下(ATP,谷氨酸)发生部分胞吐,而在高强度刺激下(氰化钾)则发生完全胞吐。进一步研究表明,溶酶体中含有大量ATP,并且在部分胞吐时少量释放ATP,完全胞吐时大量释放ATP,同时释放溶酶体酶。选择性地裂解星型胶质细胞的溶酶体,发现ATP释放和钙波传播都消失了。总之,星型胶质细胞的溶酶体可以通过调节性胞吐对生理和病理条件下的细胞间信号传递产生重要意义。 相似文献
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在个体的正常发育和异常分化中,细胞间相互关系起着很重要的作用。间叶细胞影响上皮细胞的分化,真皮决定着表皮的分化,间叶细胞影响内胚层细胞,骨髓基质细胞影响血细胞的生长分化,都说明细胞-细胞的相互作用在正常细胞分化中的影响。细胞间正常平衡关系破坏是导致异常分化或肿瘤发生的原因之一。如多瘤病毒诱发上皮癌要有间质参与,癌变发生中上皮细胞和基质细胞都发生变化,并相互影响,癌侵润和结缔组织的关系,以及一些细胞分泌的生长调节因子影响另一些细胞的分化或恶性转化,都分别进行论述。 相似文献
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各学科互相渗透形成众多的边缘学科,这是当代科学发展的重要特点。细胞学和细胞遗传学同分类学之间的渗透,出现了细胞水平的分类学——细胞分类学。形态-地理学标准是传统分类学的主要方法。本世纪以来,由于实验生物学的蓬勃发展,分类学曾一度遭到冷落。然而,实验对象必须正确鉴定,实验所得信息需要记录和储存在确切的信息库内;自然界又发现不少兄弟种(sibling species)它们在形态上不能或难以区别,但却有被保护的独立的基因库。因此形态-地理学的物种概念被生物学物种概念所替代。与此同时,实验生物学,特别是 相似文献
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应用酶细胞化学方法对基因转导前后的P815小鼠肥大细胞瘤细胞进行酸性磷酸酶、非特异性酯酶及多糖的定位。研究结果显示,空载体转导的P815/neo细胞与其亲本细胞相比无显著改变,而IL2基因修饰的P815细胞的酸性磷酸酶及多糖反应明显增强,可能提示细胞内某些细胞器的形成以及细胞内多糖类合成功能的增强。 相似文献
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众多研究表明,胰岛移植的短期效果较显著,但长期效果仍不尽人意。在胰岛移植的早期,绝大多数病人可以获得明显的治疗效果,而后大多数的病人发生进行性的胰岛功能丧失,产生这种现象的原因至今仍不甚明了。如何解决移植胰岛的长期存活问题对于胰岛移植的临床应用至关重要。近年来人们对胰岛移植失败的原因进行了不断探索,发现胰岛移植后期的失败不仅与免疫反应有关,而且与移植物的细胞组成有密切关系,即胰岛细胞间的相互作用对移植物的功能维持可能有重要影响。因此,本文就胰岛α细胞及其分泌的胰高血糖素对β细胞功能的影响作一综述。 相似文献
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Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis
It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis. 相似文献
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正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases 相似文献
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Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme
responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare
the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show
that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by
distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of
demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least
one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of
the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable
potent antiproliferative synthetic drugs. 相似文献
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RICHARD E. NORRIS 《Botanical journal of the Linnean Society. Linnean Society of London》1991,106(1):1-40
Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera. 相似文献
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JOAN VALUÈS MONTSERRAT TORRELL NÚRIA GARCIA JACAS 《Botanical journal of the Linnean Society. Linnean Society of London》2001,137(4):399-407
Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted. 相似文献