利用碳氮稳定同位素技术分析东海银鲳食性

利用稳定同位素技术分析了东海银鲳(Pampus argenteus)及其可能摄食饵料的碳、氮稳定同位素比值,以期探讨东海银鲳可能的食物来源.结果表明:东海区银鲳平均碳(813C)和氮(δ15N)稳定同位素比值分别为-18.22‰、8.16‰,其可能摄食饵料的δ13C值变化范围为-17.33‰～-21.58‰,差值为4.25‰,δ15N值变化范围为3.89‰～7.96‰,差值为4.07‰;东海银鲳可能的食物来源主要为箭虫、虾类、水母类、头足类、仔稚鱼和浮游动物等,其中箭虫为主要可能的食物来源,其贡献率为24%～78%,平均贡献率为57%;银鲳可能摄食的其他饵料中,贡献率从大到小依次为虾类、水母类、头足类、仔稚鱼、＞1000 μm浮游动物、500～1000 μm浮游动物和100～500 μm浮游动物,其平均贡献率分别为11.8%、8.4%、7.1%、5.0%、4.9%、3.2%和2.6%.由以上结果可知,银鲳是一种广食性鱼类,其饵料种类较多,碳和氮的来源均较为复杂.     

狭额绒螯蟹的幼体发育

在水温18—20℃、盐度18‰—20‰、光照度200～600Ix的条件下,狭颚绒鳌蟹幼体发育经5个溞状幼体和1个大眼幼体期。从幼体出膜到大眼幼体出现历时15d、到仔蟹出现需23d。狭颚绒鳌蟹和中华绒鳌蟹的第一期溞状幼体可从第2触角的外肢、腹部侧刺数加以区别;两大眼幼体可从额角形状、第2—4胸足指节、腹肢外肢刚毛数及尾节刚毛着生情况进行区分。     

盐度对军曹鱼胚胎和仔鱼发育的影响

观察比较了不同盐度梯度(20、23、26、29、32、35、38、41和44)下军曹鱼受精卵的沉浮性、孵化率和畸形率以及测定了不同盐度梯度(10、14、18、22、26、30、34、38、42和44)下仔鱼不投饵存活系数SAI值。结果表明,受精卵在海水盐度32以上为完全浮性,26以下为完全沉性。军曹鱼受精卵孵化的最适盐度范围为29～38,适宜盐度范围为26～41,其中23～26和41～44分别视为受精卵孵化在低盐区和高盐区的两个临界区域,在此盐度上下,军曹鱼受精卵孵化率大幅度下降而仔鱼畸形率大幅度上升。试验盐度范围内军曹鱼仔鱼SAI值为2.32～16.24,仔鱼生长和存活的最适盐度范围为26～34,适宜盐度范围为22～38,而盐度18～22及38～42可分别视为军曹鱼仔鱼存活率在低盐区和高盐区的两个临界区域。     

象山港蓝点马鲛(Scomberomorus niphonius)摄食习性

2015年4月3日—6月10日利用方形网采集象山港水域仔稚鱼,分析蓝点马鲛(Scomberomorus niphonius)摄食习性及其与饵料生物的相关性。期间共进行10个航次的调查,采集蓝点马鲛仔稚鱼1108尾,体长范围4.0~41.1 mm,其中587尾个体用于摄食分析。结果表明:象山港蓝点马鲛仔稚鱼的饵料生物有11种,其中鱼类仔鱼个体占98.6%,以斑鰶(Konosirus punctatu)、鰕虎鱼(Gobiidae)、鮻(Chelon haematocheilus)等为主要种类;摄食率随生长发育逐渐升高,卵黄囊仔鱼摄食率最低(为20.4%),弯曲期及之后的个体摄食率均在60%以上;蓝点马鲛仔稚鱼口裂较大,占体长的16.4%~25.1%,且与体长呈极显著正相关(P0.01);随个体生长发育,饵料体长逐渐增大且范围变广,与蓝点马鲛仔稚鱼的体长和口裂长均呈极显著正相关(P0.01);调查期间饵料生物丰度出现3个波峰,蓝点马鲛仔稚鱼主要出现在饵料生物丰度的第二波峰期间,经Pearson相关分析表明蓝点马鲛仔稚鱼与饵料生物丰度呈显著相关(P0.05)。     

池养条件下似刺鳊(鱼句)早期发育阶段的摄食与生长特性

对人工培育的似刺鳊(鱼句)(Paracanthobrama guichenoti)仔鱼、稚鱼和幼鱼的生长与摄食节律进行了研究.结果显示,在1~70日龄间,似刺鳊(鱼句)全长平均日增长率为3.55%,体重平均日增长率为11.26%,头长/全长值随着13龄的增长而变小.全长(L,mm)与体重(M,mg)的关系式为M=0.001 2 L2-0.056 4L+0.650 4;体重(M,mg)与日龄(D,d)的关系式为M=0.004 3 e0.0936D;全长(L,mm)和日龄(D,d)的关系式为L=0.015 4 D2-0.012 8 D+8.196 5.在饵料充足的条件下,20日龄晚期仔鱼全天均有很高的摄食发生率,小高峰出现在8:00时;40日龄稚鱼则表现出明显的昼夜摄食节律,属于典型的白天摄食类型,日摄食率2.337 6%.20 13龄仔鱼和40日龄稚鱼饱食后分别经6 h、5 h整个消化道排空.在水温25℃及饥饿空胃状态下,10日龄仔鱼只经3 d即开始出现死亡个体,经5 d全部死亡;20日龄仔鱼经6 d开始出现死亡个体,经9 d全部死亡;40 13龄稚鱼经7 d才开始出现死亡个体,10 d后全部个体均死亡.     

池养条件下似刺鳊鮈早期发育阶段的摄食与生长特性

对人工培育的似刺鳊鮈（Paracanthobrama guichenoti）仔鱼、稚鱼和幼鱼的生长与摄食节律进行了研究。结果显示,在1～70日龄间,似刺鳊鮈全长平均日增长率为3．55％,体重平均日增长率为11．26％,头长／全长值随着日龄的增长而变小。全长（L,mm）与体重（M,mg）的关系式为M=O．0012L^2-0．0564L＋0．6504;体重（M,mg）与日龄（D,d）的关系式为M=O．0043e^0.0936D;全长（L,mm）和日龄（D,d）的关系式为L=0．0154D^2-0．0128D＋8．1965。在饵料充足的条件下,20日龄晚期仔鱼全天均有很高的摄食发生率,小高峰出现在8：00时;40日龄稚鱼则表现出明显的昼夜摄食节律,属于典型的白天摄食类型,日摄食率2．3376％。20日龄仔鱼和4013龄稚鱼饱食后分别经6h、5h整个消化道排空。在水温25℃及饥饿空胃状态下,10日龄仔鱼只经3d即开始出现死亡个体,经5d全部死亡;20日龄仔鱼经6d开始出现死亡个体,经9d全部死亡;40日龄稚鱼经7d才开始出现死亡个体,10d后全部个体均死亡。     

燕鳐受精卵的孵化与仔幼鱼培育的初步研究

燕鳐是黄海沿岸重要鱼种之一。本文描述了燕鳐受精卵与仔幼鱼发育的形态特点和培育条件。 烟台崆蛔岛沿岸的燕鳐,5月底开始产卵,7月结束。人工受精在船上进行。受精卵和仔幼鱼在室内用静止水进行培育。 仔幼鱼的主要饵料是皱褶臂尾轮虫和卤虫幼体。幼体在室内水泥池(0.8立方米)进行培育。 受精卵和幼体在水温20.0—27.2℃,盐度31.28—31.74‰,pH8.32—8.52,溶氧(DO)1.52—8.32毫克/升的条件下进行培育。共育成幼鱼4801尾,到1981年9月20日,幼鱼最大全长92毫米。 1982年又进行了重复试验,共育出幼体6万余尾。     

日本鬼鲉胚胎发育及仔、稚鱼形态学观察

对日本鬼鲉的胚胎及仔稚鱼形态发育进行观察,描述了各发育时期的发育时序和形态特征。日本鬼鲉的受精卵呈正圆球形,无色透明,无油球,平均卵径为(1.42±0.04)mm,呈浮性。在水温(22±0.5)℃,盐度31‰的条件下,历时约52h10min完成孵化。初孵仔鱼全长(3.04±0.13)mm,卵黄囊长(2.23±0.08)mm,卵黄囊高为(1.65±0.06)mm,在(21±0.5)℃水温下,仔鱼孵化后3d内营内源性营养(卵黄囊仔鱼),第4天卵黄囊完全消失,开口摄食轮虫。13d全长(7.12±0.35)mm,背鳍鳍条出现进入稚鱼早期,15d全长(7.92±0.61)mm鱼体及各鳍开始出现金黄色斑纹,25d全长(13.66±0.55)mm,整个鱼体呈黄褐色,完成变态进入幼鱼期,开始营底栖生活。同时观察了自胚胎发育至幼鱼期鱼苗体表色素分布的变化及其器官发育的形态变化。     

怀头鲇早期发育阶段消化酶及碱性磷酸酶活性变化(英文)

采用动物性饵料和人工饲料培育1～10日龄怀头鲇(Silurus soldatovi)仔稚鱼,分析测定了全鱼酸性、碱性蛋白酶、淀粉酶、脂肪酶以及碱性磷酸酶的活性。结果表明:孵化后3天开口期仔鱼已具有较高的碱性蛋白酶活性,5日龄时碱性蛋白酶比活力达到较高值,8日龄时出现低值,总体变化呈波动上升趋势;酸性蛋白酶活性在1～8日龄处于较低水平,8日龄后开始迅速升高;淀粉酶活性在5日龄左右达到最高值,随后酶活性开始下降至较低水平;脂肪酶活性变化波动较大,表现为双峰型,两个峰值分别出现在3～4日龄和6～8日龄。摄食动物性饵料仔稚鱼消化酶活性和碱性磷酸酶活性均高于摄食人工饲料。在整个早期发育过程中,碱性蛋白酶比酸性蛋白酶活性高,碱性蛋白酶、淀粉酶比活力在约8日龄仔稚鱼转变期明显下降,而酸性蛋白酶活性开始迅速升高,这说明消化酶活性的变化与仔稚鱼发育过程中消化机能转换具有相关性。怀头鲇在10日龄内碱性磷酸酶活性呈上升趋势,表明怀头鲇胃肠道功能的逐步发育完善。     

东海竹筴鱼的食性

以2008年5月、8月、11月和2009年2月东海灯光围网采集到的453条东海竹筴鱼为研究对象,对其胃含物进行分析,应用K-W非参数检验、卡方检验、聚类分析等方法,对不同季节和发育阶段条件下东海竹筴鱼的食性进行研究.结果表明: 东海竹筴鱼的饵料生物有124种(包括未鉴定种),浮游甲壳类和小型鱼类为其主要饵料类群.优势饵料生物依次是麦氏犀鳕(IRI%=39.2%)、长尾类糠虾幼体(IRI%=18.4%)、短尾类大眼幼体(IRI%=7.6%)和太平洋磷虾(IRI%=6.6%)等.季节和叉长对东海竹筴鱼的摄食强度均有显著影响(P<0.01),东海竹筴鱼春季摄食强度最高,而冬季最低;叉长140～159 mm的竹筴鱼摄食强度最高,叉长45~99 mm的幼鱼的摄食强度较高,其余叉长的鱼摄食强度相对较低.聚类分析结果表明,叉长100 mm是东海竹筴鱼摄食取向的拐点.东海竹筴鱼四季的平均营养级为3.51,属于低级肉食性鱼类.     

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.