褶纹冠蚌()和三角帆蚌(■)人工杂交试验

1.要求通过杂交种能培育大型珍珠。目前较好的育珠河蚌是三角帆蚌(Hyriopsis cumingii)和褶纹冠蚌(Cristaria plicata),但它们的育珠性状还不理想。三角帆蚌所产珍珠,质量虽佳,但插核植片部位的壳间距离小,不能育成大珠;褶纹冠蚌体型大,插核植片部位的壳间距离也大,外套膜厚实,能插大核植大片育成大型     

畸形珍珠和污珠产生的原因分析

珍珠质量表现在“圆”、“光”、“大”、“彩”上,也就是说,珍珠形状要圆,颗粒要大,其全身呈闪烁珠光且具宜人的色彩。但是一般生产上会产生污珠、无光泽的珠以及大量不规则的畸形珍珠,造成大量废珠和质量低劣的珍珠。     

褶纹冠蚌光珠与骨珠珍珠囊差异的研究

运用多种组织化学方法和电镜技术研究了褶纹冠蚌光珠和骨珠珍珠囊表皮细胞的形态结构、分泌物性质和功能等方面的差异。结果表明：骨珠珍珠囊表皮细胞合成和分泌珍珠前体物质的能力较光珠的强,故骨珠的形成速度比光珠快;光珠和骨珠珍珠囊表皮细胞合成和分泌的蛋白质的差异决定了光珠和骨珠的形成;光珠和骨珠珍珠囊表皮细胞的形态结构特征差异可作为检验和预测人工培育珍珠质量的细胞学标准。     

背角无齿蚌珍珠囊形成过程的组织学和酶组织化学研究

本文采用Ｈ．Ｅ染色法和酶组织化学方法,对背角无齿蚌珍珠囊形成过程的组织学和酶组织化学的变化情况进行了研究,证实了“初生珍珠囊”的形成和溶解及“次生珍珠囊”的形成,并推没“次生珍珠囊”表皮细胞是由育珠蚌结缔组织转化而来的;观察了育珠手术后九种酶在珍珠囊形成的各个阶段和在珍珠囊和育珠蚌不同部位的变化情况,说明了珍珠囊珙成过程是与复杂的能量代谢,物质代谢及物质转运等有关的生理生化过程。     

盐度对企鹅珍珠贝足丝分泌的影响

企鹅珍珠贝（Pteria penguin）是生产附壳珍珠的大型海水经济贝类,其依靠强壮的足丝将自身固定在硬质基底上,抵抗水流的冲击和抵御被捕食等。足丝分泌和足丝的形状很容易受到环境的影响,本实验采用盐度30为低盐度组、盐度35为中盐度组和盐度40为高盐度组,研究这3种盐度对企鹅珍珠贝足丝分泌、足丝直径和足丝拉力的影响,通过单因素方差分析法（LSD法）分析这三个足丝相关指标在3种盐度组间是否存在显著性差异。结果显示,3种盐度下企鹅珍珠贝足丝附着率无显著差异,但在整个实验周期72 h内,中盐度组的足丝分泌总数为（48.7 ± 15.1）根,显著高于低盐度组的（24.7 ± 5.0）根和高盐度组的（13.3 ± 1.5）根。在实验的前6 h内,中盐度组的足丝首次附着率显著高于低盐度组和高盐度组（P < 0.05）,但在后续的12 h、18 h、30 h、42 h、54 h和66 h这6个时间点,3个盐度组的足丝首次附着率均无显著性差异。足丝直径未受盐度变化的影响,但盐度对足丝拉力具有显著影响,中盐度组的足丝拉力显著高于低盐度组和高盐度组（P < 0.05）。上述结果表明,企鹅珍珠贝为适应一定范围内盐度的改变,会在短时间内通过抑制足丝分泌来减少能量消耗,随着对环境的适应足丝分泌会恢复。盐度影响足丝分泌且对足丝拉力影响显著,但对足丝直径无明显影响。本研究可以为企鹅珍珠贝养殖及珍珠插核培育提供理论基础。     

熊果苷和丙戊酸影响企鹅珍珠贝(Pteria penguin)贝壳色泽

企鹅珍珠贝(Pteria penguin)是我国最具潜力培育大型海水珍珠的优质母贝,其贝壳色泽及珍珠层颜色与黑色素(melanin)的合成水平有关。为了筛选安全有效的企鹅珍珠贝黑色素抑制剂和增强剂,探讨其有效使用浓度和作用时间,分析其毒副作用,实验分别采用不同浓度的熊果苷(arbutin)和丙戊酸(valproic acid)浸泡1月龄稚贝不同时间,观察3月龄,5月龄和7月龄幼贝壳色,并统计熊果苷和丙戊酸的使用对幼贝变色率、存活率、壳长、壳高、壳宽的影响。结果显示,2 mmol/L熊果苷处理稚贝1h或5 mmol/L丙戊酸处理1h即可显著提高壳色变异的比率(p0.05),且幼贝变色率随熊果苷和丙戊酸的浓度和作用时间的增加而增加。对熊果苷和丙戊酸的毒性检测发现,熊果苷达到10 mmol/L处理8h时,仍不会影响幼贝的存活率、壳长、壳高、壳宽(p0.05);但丙戊酸在浓度为5 mmol/L处理4h时,幼贝的存活率即显著下降,壳长、壳高和壳宽亦显著低于对照(p0.05)。研究表明,熊果苷和丙戊酸对企鹅珍珠贝幼贝而言分别是有效的黑色素抑制剂和增强剂,熊果苷在10 mmol/L处理8h以下都未检测到毒副作用,丙戊酸在5 mmol/L处理4h时即存在一定毒性。     

珍珠颜色和贝壳珍珠层颜色研究进展

颜色及其色度均一性是衡量珍珠价值的重要指标之一。珍珠颜色及贝壳珍珠层颜色的研究涉及多个学科领域,研究表明,珍珠的颜色与制片蚌外套膜对应的珍珠层颜色相一致,而蚌的珍珠层颜色主要由遗传因素决定。现有的研究资料对珍珠层颜色形成的机理虽然还不能给出一个系统、合理的诠释,但金属元素、卟啉、类胡萝卜素和物理结构等因素可能和珍珠层颜色形成密切相关,珍珠层中含有少量以蛋白质为主的有机基质,这些蛋白调控珍珠层的结构和颜色的形成,可能是解释珍珠层颜色形成机理的关键。本文对珍珠颜色和贝壳珍珠层颜色研究进展进行系统综述,探讨珍珠颜色的影响因素及相互关联,旨在为进一步研究珍珠和贝壳珍珠层颜色提供借鉴与思路。     

河蚌育珠的饲养管理

我县地处江南水乡,河池密布,有利于发展河蚌育珠生产。遵照毛主席关于“以粮为纲,全面发展”的教导,我县不少生产队生产珍珠已成为一项主要副业收入,对支援国家建设,供应药用,壮大集体经济起了一定的作用。 河蚌育珠生产饲养管理是不可忽视的经常性工作,对提高珍珠产量、质量及减少手术蚌的死亡率,都     

育珠蚌的生物学特性及其繁殖技术

育珠蚌的繁殖比较特别,发生中的钩介幼虫一定要寄生在鱼的鳃和鳍条上,赖以生存而变态成稚蚌。由于大部分的钩介幼虫遇不到中间宿主而夭折,所以,靠天然增殖育珠蚌资源是十分有限的,不能满足育珠生产发展的需要。为了改变这一状况,适应育珠生产发展的需要,人们开展了人工繁殖育珠蚌的技术研究。现将其生物学特性及繁殖要点介绍于下:一、育珠蚌的生物学特性育珠蚌是软体动物,体外有两片对称的蚌壳包被,蚌壳呈墨色或黄褐色,由三层组成。最外层为角质层,中间为棱柱层,内层为珍珠层。上述     

三种不同因子对三角帆蚌外套膜细胞Ca~(2+)流动性的影响

<正>三角帆蚌(Hyriopsis cumingii)是我国主要的育珠母蚌,其所培育出的珍珠色泽鲜艳、细腻光滑,因而成为目前淡水育珠生产中首选的育珠母蚌之一。蚌的外套膜是贝壳和珍珠形成的重要组织器官,有内外两层表皮细胞及其间的结缔组织构成。它对钙具有高度通透性,其上皮细胞具有通过细胞膜主动吸收Ca~(2+)和贮存Ca~(2+)的功能,并通过胞吐作用排出钙至外套膜外腔中,这些钙就是形成珍珠的基础。维     

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     

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.     

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.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

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).     

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.