微流水培养条件下斑鳜仔鱼的摄食与生长

在孵化环道连续微流水培养、水温(24±2)℃条件下,斑鳜(Siniperca scherzeri Steindachner)初孵仔鱼全长为(4.87±0.10)mm(n=50),卵黄囊体积为(1.461±0.172)mm3(n=50),油球直径为(0.47±0.04)mm(n=50).仔鱼孵出12h,胸鳍增大,具有一定阵发性水平游动能力,1日龄巡游模式建立;2日龄口膜消失,开始主动摄食,进入混合营养期,3 日龄外源性摄食关系完全建立.5日龄仔鱼的卵黄和油球全部消失.进入外源营养期;15日龄全长达到(13.72±0.76)mm(n=12).仔鱼发育过程中,其全长生长存在内源性营养阶段的较快速生长,混合营养阶段的慢速生长以及外源性营养阶段的快速生长三个生长期相,平均增长率为0.59 mm/d,对仔鱼全长TL(mm)与日龄D(d)进行同归,其生长模型为:TL=-0.0004D3+0.0283D2+0.2159D + 4.9335(R2=0.985,n=261).2-15 日龄,口宽与全长呈正比关系.仔鱼从初孵到PNR仅为5-6d,具有摄食能力的时间4d,仔鱼依赖外源性营养开始时间较早,对饥饿的耐受力较差.     

太平洋鳕仔鱼饥饿实验及不可逆生长点的确定

通过研究饥饿胁迫对太平洋鳕仔鱼生长、形态和行为的影响,确定太平洋鳕仔鱼最佳投饵时间及不可逆点,以期为太平洋鳕人工育苗提供科学参考。实验设饥饿组和摄食组进行研究。结果表明,在水温10.0—11.0℃时,太平洋鳕仔鱼在孵化后第5天开始摄食,此时卵黄囊容量约从初孵时的0.2402mm3降至0.0062mm3,卵黄囊体积随仔鱼生长逐渐变小。从第8日龄开始,饥饿仔鱼的全长、体长、肛前长、体高等指标与摄食组差异极显著(P0.01),多项生长指标出现负增长,饥饿组与摄食组仔鱼开鳔率及鳔体积差异明显,表明饥饿对仔鱼生长发育起延迟作用。太平洋鳕仔鱼初次摄食率为30%,第7天初次摄食率达90%,仅保持1d。太平洋鳕仔鱼的耐饥饿能力较差,PNR为9日龄。最佳投饵时间为5—7日龄。     

美洲鲥胚胎及仔稚鱼的发育

对美洲鲥(Alosa sapidissima)早期生活史阶段的生长发育特征进行了观察和测量, 描述了胚胎和仔、稚鱼的生长发育特征。美洲鲥受精卵球形、无油球, 为沉性卵, 卵径2.85-3.28 mm。在水温20.3℃-21.9℃孵化条件下, 经过82h 孵化出膜, 根据其胚胎发育过程的形态特征, 胚胎发育分为受精卵、卵裂期、囊胚期、原肠胚期、神经胚期、器官形成期和出膜期7 个发育阶段。美洲鲥初孵仔鱼全长为(8.56±0.36) mm, 其卵黄囊体积为(4.57±0.77) mm3。1 日龄仔鱼脑部发育明显, 口张开, 肛门开通, 胸鳍形成。2 日龄仔鱼卵黄囊体积(0.71±0.23)mm3, 只有刚孵化的15.54%。3 日龄仔鱼经过1d 的混合营养期, 卵黄被完全吸收, 4 日龄仔鱼完全营外源性营养, 卵黄囊的体积(V)随孵化时间(h)的变化方程为V=4.1583e?0.0356h(R2=0.9901)。此后, 背鳍鳍条、尾鳍鳍条、臀鳍鳍条和腹鳍鳍条相继在晚期仔鱼出现, 9 日龄仔鱼尾椎开始弯曲, 21 日龄仔鱼尾椎弯曲完成。27 日龄鱼鳞开始形成, 到33 日龄稚鱼全身披鳞, 个体发育进入幼鱼期, 仔稚鱼期间的生长模型方程为: TL=0.0049D2+0.5091D+9.2578 (R2=0.9885, TL 为全长, D 为日龄)。       

延迟投饵对厚颌鲂仔鱼的影响

在室内养殖条件下,研究厚颌鲂仔鱼的摄食、耐饥饿和恢复生长能力.试验结果表明:(1)仔鱼在孵出后2～3 d开口摄食,卵黄囊在之后的2 d耗尽,饥饿仔鱼在12～13日龄达到不可逆点(PNR);(2)饥饿仔鱼的初次摄食率在卵黄囊耗尽时达到最高,保持在80%以上的时间为7 d;(3)仔鱼在PNR后死亡率急剧增加,PNR后第3 d仔鱼全部死亡;(4)经恢复生长试验,延迟3 d投饵对仔鱼的存活率影响不大,延迟3～6 d投饵对仔鱼全长生长影响不大.     

哲罗鱼仔鱼饥饿实验及不可逆生长点的确定

在水温10-12℃条件下,研究了哲罗鱼Hucho taimen仔鱼饥饿对其生长、形态和行为的影响,确定其初次摄食饥饿不可逆点(PNR)和最佳初次摄食时间.结果表明:饥饿状况下哲罗鱼仔鱼全长基本维持恒定,但肥满度不断降低,在第24日龄后体重出现负增长,其卵黄囊吸收与生长变化密切相关;饥饿后的仔鱼身体发黑、头大身瘦、后脑部下陷;集群性、初次摄食力与饥饿时间呈负相关;25日龄出现自残现象,30日龄自残率达到最大值14.5%.哲罗鱼仔鱼初次摄食时间在21日龄,当29日龄摄食率达到最高值100%,PNR期为39-40日龄;初次摄食仔鱼最佳投喂时间在25日龄,也就是仔鱼上浮后第4天.     

施氏鲟仔鱼发育及异速生长模型

施氏鲟仔鱼的生长发育可分为两个时期:卵黄囊期(或称为自由胚期),即从刚出膜(0日龄,10.17±0.63 mm)到初次开口(9日龄,18.93±0.74 mm);晚期,从开口摄食至器官发育基本完全(38日龄,41.89±5.09 mm).卵黄囊期仔鱼的感觉、摄食、呼吸、游泳等器官快速分化;晚期仔鱼各骨板分化并发育,在形态上逐渐完成向成鱼的转变.对施氏鲟仔鱼异速生长进行的研究表明,仔鱼许多关键器官均存在异速生长现象,如眼径、口宽、尾鳍长、胸鳍长分别在2日龄、8～9日龄、10日龄、11日龄出现生长拐点,拐点之前器官快速生长,拐点之后生长速度减慢甚至近似等速生长.施氏鲟仔鱼各器官呈现出协调和快速发育的特征,随着重要的感觉、摄食、呼吸、游泳等器官的发育和完善,仔鱼快速地具备了躲避敌害和摄食的能力,其生存能力大大提高.     

施氏鲟仔鱼发育圾异速生长模型

施氏鲟仔鱼的生长发育可分为两个时期:卵黄囊期(或称为自由胚期),即从刚出膜(0日龄,10.17±0.63 mm)到初次开口(9日龄,18.93±0.74 mm);晚期,从开口摄食至器官发育基本完全(38日龄,41.89±5.09 mm).卵黄囊期仔鱼的感觉、摄食、呼吸、游泳等器官快速分化;晚期仔鱼各骨板分化并发育,在形态上逐渐完成向成鱼的转变.对施氏鲟仔鱼异速生长进行的研究表明,仔鱼许多关键器官均存在异速生长现象,如眼径、口宽、尾鳍长、胸鳍长分别在2日龄、8~9日龄、10日龄、11日龄出现生长拐点,拐点之前器官快速生长,拐点之后生长速度减慢甚至近似等速生长.施氏鲟仔鱼各器官呈现出协调和快速发育的特征,随着重要的感觉、摄食、呼吸、游泳等器官的发育和完善,仔鱼快速地具备了躲避敌害和摄食的能力,其生存能力大大提高.     

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.     

鸭绿江唇仔、稚鱼形态发育与早期生长

通过观察、拍照和测量的方法对鸭绿江唇(Hemibarbus labeo)仔、稚鱼的形态发育和早期生长进行了研究。结果表明:在19.6—25.8℃的试验条件下,唇初孵化仔鱼全长为(7.92±0.29)mm,2日龄头部两侧出现感觉芽;3日龄鳔一室原基形成,5日龄红色的脾出现,且仔鱼开口;7日龄卵黄囊吸收完毕,9日龄脊索末端开始向上弯曲;10日龄鳔二室形成,14日龄脊索弯曲完成,尾鳍边缘开始内凹;32日龄鳞片开始出现在鳃盖后缘的体表,同时各鳍发育完全,个体发育进入稚鱼期,43日龄全身被鳞,个体发育进入幼鱼期。根据卵黄囊、脊索和鳞片的变化,唇胚后发育可细分为卵黄囊期(0—6日龄)、弯曲前期(7—9日龄)、弯曲期(10—14日龄)、弯曲后期(15—32日龄)和稚鱼期(33—43日龄)。试验期间,全长和体质量的特定生长率分别为3.32%和12.16%;卵黄囊体积(V)与日龄(d)的关系为V=0.0048d3–0.0309d2–0.1240d+0.8453(R2=0.8933);全长(LT)、体质量(W)与日龄均为指数函数关系,相关方程分别为:LT=8.3821e0.0329d(R2=0.9586),W=0.0048e0.0969d(R2=0.9463);头长(LH)、体高(HB)的生长方程分别为:LH=–6E–05d3+0.002d2+0.1733d+0.7862(R2=0.9577),HB=–5E–05d3+0.0039d2+0.017d+0.9389(R2=0.9621)。     

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。     

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.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

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.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

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.     

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.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细