扬子鳄消化系统组织学和细胞学研究概况

综述了扬子鳄消化系统的组织结构、超微结构、内分泌细胞种类与密度分布等,得出3个方面的结论①从消化系统组织和细胞的演化程度看,扬子鳄尚属较原始的类群;②扬子鳄消化系统组织结构、细胞的超微结构和内分泌细胞的种类与分布有较大的特异性;③扬子鳄消化系统组织和细胞的结构与功能同其取食习性是适应的.还对今后的研究工作提出了建议.     

扬子鳄消化系统组织学和细胞学研究概况

综述了扬子鳄消化系统的组织结构、超微结构、内分泌细胞种类与密度分布等,得出3个方面的结论：①从消化系统组织和细胞的演化程度看,扬子鳄尚属较原始的类群;⑦扬子鳄消化系统组织结构、细胞的超微结构和内分泌细胞的种类与分布有较大的特异性;②扬子鳄消化系统组织和细胞的结构与功能间其取食习性是适应的。还对今后的研究工作提出了建议。     

扬子鳄消化道Ghrelin免疫活性细胞的分布及其在冬眠期的密度变化

目的 研究扬子鳄（Alligator sinensis）消化道中生长素释放肽ghrelin免疫活性（IR）细胞的分布、组织定位及其在冬眠期的变化.方法 应用链霉亲和素-生物素-过氧化物酶复合物（SABC）免疫组织化学方法结合生物统计学分析.结果 Ghrelin-IR细胞在扬子鳄的小胃密度最高,在胃贲门部、胃体和胃幽门部有少量分布,主要位于胃腺上皮细胞之间.在食管、十二指肠、空肠、回肠和直肠中均未检测出ghrelin-IR细胞.冬眠期小胃ghrelin-IR细胞显著性减少（P〈0.01）,其它部位无显著性变化（P〉0.05）.结论扬子鳄消化道ghrelin-IR细胞的分布同其它动物有相似之处,也有其一定的特异性.Ghrelin在扬子鳄冬眠期的代谢变化和能量稳态的调节中起重要作用.     

扬子鳄角膜超微结构研究

用航向电镜研究了扬子鳄角膜的超微结构。结果表明：扬子鳄角膜由皮细胞层、Ｂｏｗｍａｎ膜、角膜基质、后弹力膜和内皮细胞层组成；与Ｕｎｄｅｒｗｏｏｄ在爬行类视觉器官综述中认为鳄类无Ｂｏｗｍａｎ膜的结果不相符。本文还描述了角膜各层的超微结构的特点。     

基于BDNF和NT-3基因部分序列探讨爬行动物系统发生中的若干问题及扬子鳄分类地位

通过两个核基因NT-3基因(约740 bp)和BDNF基因部分序列(约720 bp)的分析,对爬行动物的系统发生关系中鳄类与鸟类和哺乳类系统发生关系、龟类在爬行动物系统发生中的位置以及扬子鳄属的划分等问题进行探讨.结果表明,在NT-3基因序列中,有307个位点存在变异(约为总位点数的47.3%),BDNF基因序列有256个变异位点(约为38.79%);构建的分子系统树显示,NT-3和BDNF基因以及两序列合并数据后所得系统树的拓扑结构均支持鳄类和鸟类聚为一支构成姐妹群,鳄类与蜥蜴类尽管在形态上非常相似,但它们的亲缘关系仍然较远;同时支持把龟鳖类作为鳄类和鸟类支系的姐妹群,支持把蜥蜴类(有鳞类)放在爬行类系统发生树的基部,而不是龟鳖类作为现代爬行类中最基部的1支.对扬子鳄分类地位的研究结果支持在现存的鳄类中扬子鳄与密西西比鳄的亲缘关系较近的结论.     

扬子鳄小胃黏膜的组织化学和细胞学

扬子鳄（Alligator sinensis）的小胃是在胃幽门部与十二指肠的交接处由胃幽门括约肌和十二指肠括约肌突入管腔形成的一个小腔,其生理功能一直不清楚。本文采用组织化学、电子显微镜和免疫组织化学技术对扬子鳄小胃黏膜的组织化学成分、细胞超微结构及细胞类型进行了较全面的研究。小胃黏膜上皮PAS反应呈强阳性,AB染色呈弱阳性,主要分泌中性糖蛋白和少量的含硫酸性糖蛋白。电子显微镜下,扬子鳄小胃黏膜上皮主要由表面黏液细胞组成,偶见内分泌细胞。小胃腺部则70％-90％为内分泌细胞,其余为少量的腺黏液细胞和泌酸胃酶细胞。应用7种胃肠激素的抗血清在小胃黏膜中检测出了5-羟色胺（5-HT）、胃泌素（Gas）、胰高血糖素（Glu）、生长抑素（SS）、P-物质（SP）和血管活性肠肽（VIP）细胞,以Glu细胞密度最高,VIP细胞密度最低。未检测到胰多肽（PP）细胞。本研究结果表明,从组织化学成分和细胞类型看,扬子鳄的小胃与胃同源;从细胞超微结构和内分泌细胞所占百分比例看,扬子鳄的小胃已出现了明显的特化,泌酸胃酶细胞中未见泌酸小管,可能没有泌酸功能。内分泌细胞含量丰富,可能在调节胃肠道功能中发挥重要作用[动物学报54（6）：1044—1050,2008]。     

Present Status of Protection on Chinese Alligator' s Population and Habitat

扬子鳄(Alligator sinensis)是我国特有的古老而珍稀的爬行动物,现阶段野生扬子鳄的分布区域进一步萎缩,成为彼此孤立的点状,残存栖息地的生态环境趋于恶化,野生鳄数量估计为120 ～150条,老年化程度高.扬子鳄的保护管理依据现实状况及时加以调整,加大了野外保护力度,逐步改善野生鳄的栖息生境,实施野外放归工程,初步遏制了野生鳄数量迅速下滑的局面.人工饲养种群数量已逾10 000条,当前人工饲养繁殖的重点是管理好有限的遗传多样性资源.扬子鳄的研究主要涉及形态学、解剖学、组织胚胎学、生态学、生理生化、细胞及分子生物学,人工饲养繁殖技术等方面.营养生理和保护遗传学的应用研究有待加强.     

评介《扬子鳄》一书

由安徽师范大学陈璧辉等同志编著的《扬子鳄》专著,最近已由安徽科学技术出版社出版,它是作者对我国特产濒危物种扬子鳄进行近十年研究工作的总结。全书约26万字,附有插图159幅、生态彩色照片4版,包括绪论、形态学、生态学和人工饲养与繁殖等四章。绪论一章对扬子鳄的分类地位和系统进化作了简介;概述了从三千多年前至1984年国内外对扬子鳄的研究历史、分布、数量及历史变迁;介绍了有关鳄类形态学、染色体、某些蛋白质和抗体差异性的研究进展,并综合各家观点对世界上现存的21种鳄类的亲缘关系进行了讨论,提出有关系谱图解。     

鳄类起源进化研究有新突破

中国科学院发育生物学研究所莫鑫泉采用DNA复性动力学方法和DNA分子钟技术在扬子鳄起源和鳄类分子进化研究中,从分子水平上证实扬子鳄与密西鳄之间确曾有亲缘关系。他们从两者基因组结构的比较研究中,发现两者虽然在DNA序列种类复杂性的拷贝数上有较大差异,但总复杂性还是相似的。他们采用自己建立的DNA分子钟技术,测定了各物种从一个共同的祖先那里分枝以后的时间跨度,证明扬子鳄在3500万年前与泰国鳄有一个共同的祖先,在4500万年前与湾     

扬子鳄的起源

介绍了现存鳄彼此间的亲缘关系、扬子鳄起源的时间和地点。主要结论可归纳如下：①现存鳄类在科、属、种分类上都存在不同意见;②扬子鳄与密河鳄被分在同一属内,但两者之间的亲缘关系存在争议,两者在形态、生化、细胞、分子生物学上差异很大;③Stell认为扬子鳄在中新世开始出现,作者认为它可能起源于渐新世或中新世早期;④Stell认为分布于北美的汤氏鳄（A.thomsoni)可能是扬子鳄的祖先类型,而另一些学者认为扬子鳄起源于亚洲的可能性更大些。     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

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.     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

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     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

鸡传染性法氏囊病病毒研究进展

传染性法氏囊病(Infection bursal disease, IBD)是由鸡传染性法氏囊病毒(Infectious bursal disease virus, IBDV)引起的鸡和火鸡的一种高度接触性传染病,给世界各国的禽养殖业带来了巨大损失.自IBDV发现至今新的变异株不断出现,分子结构的改变导致病毒致病力的改变及宿主对疫苗应答的改变,使得传统的疫苗已不能控制其流行,因此各国学者对其基因组结构和功能进行了广泛深入的研究,并积极研制新型有效的疫苗以达到防治的目的.     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).