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。     

线纹尖塘鳢仔、稚鱼的形态发育

对池养条件下线纹尖塘鳢(Oxyeleotris lineolatus)的胚后发育进行定期观察,胚后发育大致可分为前期仔鱼、后期仔鱼、稚鱼和幼成鱼期。观察发现,线纹尖塘鳢的初孵仔鱼个体较小,仅2.875mm,前期仔鱼,包括混合营养仔鱼期,时间短,仅为5d,属较早建立起外源性营养摄食机制的鱼类;器官发育主要在后期仔鱼阶段完成;鳞的出现和鳞被形成在稚鱼发育阶段完成;在池塘自然水温26~30℃条件下,从初孵仔鱼到稚鱼发育期完成历时43~44d。     

拟赤梢鱼的胚胎发育和仔稚鱼生长特性观察

为阐明拟赤梢鱼(Pseudaspius leptocephalus)胚胎发育和仔稚鱼发育特点, 采用人工催产的方式获得受精卵, 观察分析了拟赤梢鱼胚胎发育和仔稚发育的时序特征。结果表明: 拟赤梢鱼成熟卵粒为黄色圆球形, 平均卵径为(1.77±0.20) mm, 遇水具微黏性; 在水温23℃条件下, 胚胎发育经历合子期、卵裂期、囊胚期、原肠胚期、神经胚期、器官形成期和孵化出膜期7个阶段26个时期, 共历时47h 55min完成孵化过程。初孵仔鱼在(23±1)℃水温条件下, 经历卵黄囊期仔鱼(0—7d)、晚期仔鱼(8—26d)和稚鱼期(27—31d), 进入幼鱼期; 卵黄囊期仔鱼游泳能力差, 随着卵黄囊逐渐消耗, 体表色素斑、胸鳍和尾鳍等逐渐形成, 消化道贯通, 鳔充气; 晚期仔鱼卵黄囊完全消失, 仔鱼游泳能力增强, 开口摄食, 腹鳍形成, 皮肤透明; 稚鱼期鳞片形成并覆盖全身, 鱼体形态已逐渐与成鱼无异。拟赤梢鱼仔稚鱼阶段全长生长特性公式为TL=0.0125x2+0.3579x+6.2058 (R2=0.9953), 出膜15d内, 仔鱼生长速度缓慢, 全长日生长率仅为(0.38±0.02) mm/d, 15d后, 仔鱼生长速度变快, 全长日生长率可达(1.24±0.09) mm/d。研究初步阐明了拟赤梢鱼的胚胎发育和仔稚鱼发育的时序特征, 为拟赤梢鱼的苗种规模化繁育提供了理论基础。     

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)。       

宽口光唇鱼胚胎发育的研究

在涪江下游宽口光唇鱼的产卵时间为4—5月,自然产卵水温为17℃—23℃。产卵场位于底质为卵石和砾石的浅水滩,分散产卵,卵弱粘性,金黄色,沉性,卵径1.55—2.11mm,卵膜外径2.27-2.55mm。在水温19.5—21.2℃条件下,胚胎从受精到孵化出膜共历时56h30min,初孵仔鱼全长6.0-6.2mm,肛后长/全长=24.14％,卵黄囊前部为膨大的球形,后部为均匀的棒状。     

大渡软刺裸裂尻鱼仔鱼形态发育及生长

通过人工干法授精获得大渡软刺裸裂尻鱼的受精卵,观察了实验室孵化培育条件下的仔鱼形态变化过程。结果表明:在平均水温为11.86℃(9.0~16.0℃)下胚胎历时9 d出膜。初孵仔鱼全长11.65 mm±0.27 mm,鳃弓、口凹和肛门原基明显,眼色素和胸鳍原基出现,肌节43对(12+20+11),心跳140~160次/min。出膜9 d,仔鱼肠道贯通,鳔雏形和背鳍原基出现。臀鳍原基出现和尾鳍分叉分别于出膜后13 d和16 d发生。出膜19 d,腹鳍原基出现,此时背鳍鳍条4~6枚,臀鳍鳍条2~4枚。出膜32 d,鱼体全长22.99 mm±0.65 mm,除存在少量鳍褶外,基本具备成鱼的形态特征。仔鱼卵黄于出膜第12天吸收完全,卵黄囊体积与出膜后天数呈显著的多项式相关(P0.01)。体长、全长、头长和肛后长的生长均呈明显的二项式关系。研究结果丰富了大渡软刺裸裂尻鱼早期发育生物学资料,为人工养殖研究等提供参考。     

西江鲤仔稚鱼生长及消化酶活性变化

为了探究了鲤(Cyprinus carpio)仔稚鱼的生长过程中主要消化酶活性变化规律, 实验测定了鲤从孵化出膜到40 日龄(日龄, Day after hatching)仔稚鱼期间的生长、可溶性蛋白含量和几种消化酶活性变化。结果显示: 仔稚鱼全长以及体重在15 日龄后增速加快, 特定生长率为14.81%。淀粉酶、脂肪酶、胰蛋白酶, 糜乳蛋白酶、碱性磷酸酶以及氨基肽酶在1 日龄仔鱼体内均能检测到活性。在仔稚鱼发育过程中, 其可溶性蛋白含量先下降后上升。仔鱼摄食前消化酶的活性出现一定的上升, 随着仔稚鱼消化系统发育以及营养方式的转变, 其消化酶活性从3到25 日龄处于不断的变化状态, 而25 日龄到实验结束鲤仔稚鱼的消化酶处于一种相对稳定的状态, 标志着其消化功能趋于完善。根据不同发育时期鲤消化酶活性的变化, 设计有机可腐化的材料制备人工鱼巢以提高人工鱼巢的生态修复功能, 降低饥饿对仔稚鱼成活率的影响。     

松潘裸鲤仔稚鱼耳石生长轮日周期确证及其孵化期推算

以2015年和2016年在孟屯河上游捕获的仔稚鱼为研究对象, 对其种属进行了鉴定, 观察了耳石形态特征、确证了耳石轮纹沉积规律, 并基于耳石日轮技术对其孵化期进行了推算。结果表明: 基于线粒体细胞色素氧化酶亚单位Ⅰ(Cytochrome oxidase subunit Ⅰ, COⅠ)序列构建的系统进化树显示, 采集仔稚鱼为松潘裸鲤(Gymnocypris potanini)。在松潘裸鲤仔稚鱼生长过程中, 微耳石由近圆形发育成贻贝形, 矢耳石由锲形发育为箭矢状。采用温度标记处理松潘裸鲤仔稚鱼, 确定耳石轮纹沉积具有日周期性, 生长轮为日轮。依据耳石日轮数, 结合采样时间及耳石轮纹沉积规律, 并采用大多数裂腹鱼类日龄为日轮数N+1的关系, 推算出2015年松潘裸鲤样本的孵化时间为6月29日至7月15日, 2016年样本孵化时间为7月13日至8月18日, 这些结果为研究松潘裸鲤野生种群繁殖期及其资源保护等提供了基础数据。     

裸项栉鰕虎鱼的全人工繁殖及其胚胎发育

目的研究裸项栉鰕虎鱼全人工繁殖及胚胎发育,为该鱼的实验动物化研究奠定基础。方法对胚胎和仔稚幼鱼各个发育期的连续取样,系统地观察了裸项栉鰕虎鱼各发育期的形态变化及生长特征。结果水温25．8℃～26．5℃,裸项栉鰕虎鱼受精后约82h仔鱼开始出膜,初孵仔鱼全长1．42～1．73mm,1d开口摄食,3d卵黄囊消失,23d第一背鳍形成,鳞片出现;33d全身被鳞;初孵仔鱼经97d发育成熟,繁殖周期约为36d;雌鱼性腺成熟系数可达40％,个体相对生殖力达每克8193．5粒。结论裸项栉鰕虎鱼具有个体小、性成熟早、生殖季节长、繁殖周期短、繁殖力强等特点,可进行室内规模化人工繁殖和培育。     

河鲈胚胎及卵黄囊期仔鱼发育

为探究河鲈(Perca fluviatilis)早期生活史和发育生物学,采用体视解剖镜、显微镜仔细观察、测量、描述、绘图的方法,连续观察了6个批次河鲈胚胎及卵黄囊期仔鱼发育状况,进行比较分析。结果显示:(1)在水温8~13℃时,胚胎期约需265h,有效积温2540~2880℃.h;水温11~13℃时,卵黄囊期约需6d,有效积温1750~2120℃.h;(2)辐射状次级卵膜将受精卵连成长带形单层网片状,每个胚胎周围有6个胚胎,排列很有规则。胚胎卵黄囊表面有一个大圆形油球。出膜前期可见眼球色素、胸鳍突起;(3)胚胎出膜的不同步主要是由于出膜前期长短不一和孵化水温较低所致。     

壳聚糖酶的克隆表达与壳寡糖的制备分析

目的:克隆壳聚糖酶基因于大肠杆菌中实现高表达,制备壳寡糖。方法:以枯草芽孢杆菌总DNA为模板扩增壳聚糖酶基因(CSN),克隆至载体pET23a(+)上,转化菌株BL21(DE3)。重组子经0.5 mmol/L IPTG诱导后,SDS-PAGE和质谱检测与鉴定重组酶。酶纯化后水解壳聚糖,薄层色谱分析其水解产物。结果:质谱证明壳聚糖酶(31.5kDa)成功表达,表达量占菌体总蛋白的45%左右。纯化后重组酶浓度为900 mg/L,纯度95%、回收率85%,酶活力为10 000 U/mg。壳聚糖降解产物为壳二糖至壳四糖。结论:原核表达载体pET23a(+)-CSN构建正确,壳聚糖酶表达量与活性高,适用于水解壳聚糖制备壳寡糖。     

国内外蝗害治理技术现状与展望

本文首先概述了国内外蝗虫发生与为害的态势,总结了现阶段我国蝗虫发生与为害的主要特点:即农田飞蝗暴发频繁而且严重,草原土蝗的发生时常造成严重的经济损失,而且侵入城市干扰市民生活,我国与周边国家之间蝗虫过境迁移频繁,使用化学农药污染环境和农产品;分析了国内外蝗虫防治对策与技术的发展现状,重点介绍了应急防治和可持续治理对策、...     

Coiled-coil nanomechanics and uncoiling and unfolding of the superhelix and alpha-helices of myosin

The nanomechanical properties of the coiled-coils of myosin are fundamentally important in understanding muscle assembly and contraction. Force spectra of single molecules of double-headed myosin, single-headed myosin, and coiled-coil tail fragments were acquired with an atomic force microscope and displayed characteristic triphasic force-distance responses to stretch: a rise phase (R) and a plateau phase (P) and an exponential phase (E). The R and P phases arise mainly from the stretching of the coiled-coils, with the hinge region being the main contributor to the rise phase at low force. Only the E phase was analyzable by the worm-like chain model of polymer elasticity. Restrained molecular mechanics simulations on an existing x-ray structure of scallop S2 yielded force spectra with either two or three phases, depending on the mode of stretch. It revealed that coiled-coil chains separate completely near the end of the P phase and the stretching of the unfolded chains gives rise to the E phase. Extensive conformational searching yielded a P phase force near 40 pN that agreed well with the experimental value. We suggest that the flexible and elastic S2 region, particularly the hinge region, may undergo force-induced unfolding and extend reversibly during actomyosin powerstroke.     

放牧对牧草光合作用、呼吸作用和氮、碳吸收与转运的影响

研究放牧对草地植物生理活动的影响,对于揭示草地放牧演替的生理机制有重要意义.大量研究表明,家畜放牧对牧草光合作用、呼吸作用以及C和N吸收与转运的影响,可以分为生理伤害和生理恢复2个阶段.放牧通过改变草地冠层结构影响牧草光合作用,净光合作用速率短期内迅速下降,随着叶面积指数增加又逐渐上升,呼吸作用有相似的变化趋势.牧草放牧后再生长所需的C和N最初主要来自根系和留茬中的贮藏物质,此后随着牧草生长恢复逐渐由同化作用供给,C代谢与土壤N水平负相关.放牧后牧草生理活动变化与牧草遗传特性、种间竞争、家畜放牧特征、非生物环境等因素密切相关.     

Synthesis of hapten and conjugates of coumestrol and development of immunoassay

3-O-Carboxymethylcoumestrol was prepared as the hapten for immunoassay by a partial alkylation of coumestrol with ethyl chloroacetate in acetone alkalized with potassium carbonate. 3-O-Ethoxycarbonylmethylcoumestrol was separated by column chromatography and finally was hydrolyzed with formic acid. 1H and 13C NMR data (APT, COSY, HMQC, and HMBC) revealed that the reaction was regioselective, as 3-O-ethoxycarboxymethylcoumestrol was the only monosubstituted derivative. The hapten was then conjugated to bovine serum albumin and used for immunization of rabbits. A radioimmunoassay (RIA) system was established based on the polyclonal antiserum and a 125I-labeled hapten-tyrosine methyl ester conjugate as the radioligand. Parameters of the RIA: sensitivity: 12 pg per tube, 50% intercept: 140 pg per tube, working range: 20-4000 pg per tube. The cross-reactivity of a panel isoflavonoid and lignan phytoestrogens was either negligible (e.g. formononetin 0.07%; biochanin A 0.06%) or not detectable at all. The major immunoreactive peak in HPLC fractions from an alfalfa extract had the same retention time as coumestrol standard and represented 94.8% of the signal. The remaining 5.2% of immunoreactivity was distributed between five minor peaks. We conclude that after the validation for particular matrices, the method will be a useful tool for analysis of coumestrol, especially in low volume and low concentration samples.     

Kinetics and thermodynamics of peroxidase- and laccase-catalyzed oxidation of N-substituted phenothiazines and phenoxazines

N -substituted phenothiazines (PTs) and phenoxazines (POs) catalyzed by fungal Coprinus cinereus peroxidase and Polyporus pinsitus laccase were investigated at pH 4–10. In the case of peroxidase, an apparent bimolecular rate constant (expressed as k _cat/K _m) varied from 1 ×10⁷M⁻¹s⁻¹to 2.6×10⁸M⁻¹s⁻¹ at pH 7.0. The constants for PO oxidation were higher in comparison to PT. pH dependence revealed two or three ionizable groups with pK _a values of 4.9–5.7 and 7.7–9.7 that significantly affected the activity of peroxidase. Single-turnover experiments showed that the limiting step of PT oxidation was reduction of compound II and second-order rate constants were obtained which were consistent with the constants at steady-state conditions. Laccase-catalyzed PT and PO oxidation rates were lower; apparent bimolecular rate constants varied from 1.8×10⁵M⁻¹s⁻¹ to 2.0×10⁷M⁻¹s⁻¹ at pH 5.3. PO constants were higher in comparison to PT, as was the case with peroxidase. The dependence of the apparent bimolecular constants of compound II or copper type 1 reduction, in the case of peroxidase or laccase, respectively, was analyzed in the framework of the Marcus outer-sphere electron-transfer theory. Peroxidase-catalyzed reactions with PT, as well as PO, fitted the same hyperbolic dependence with a maximal oxidation rate of 1.6×10⁸M⁻¹s⁻¹ and a reorganization energy of 0.30 eV. The respective parameters for laccase were 5.0×10⁷M⁻¹s⁻¹ and 0.29 eV. Received: 20 September 1999 / Accepted: 24 February 2000     

白术同源四倍体的诱导和鉴定及其与二倍体过氧化物酶的比较

以白术（Atractylodes macrooephala Koidz.）二倍体组培苗为材料,对其四倍体诱导方法进行研究,共获得45个白术同源四倍体株系,为优良株系的选育提供了材料。此外,还分析比较了其中8个白术四倍体株系与二倍体的过氧化物酶同工酶（POD）的酶谱差异,发现四倍体各株系过氧化物酶同工酶谱比二倍体的均多了Rf0.310的谱带,且总过氧化物酶比活力也发生了很大改变,对探讨白术四倍体优良株系的生理生化机理具有一定的参考价值。     

Morphology and putative function of the colon and cloaca of marine and freshwater snakes

Among tetrapods, evidence for postrenal modification of the urine by the distal digestive tract (including the colon and cloaca) is highly variable. Birds and bladderless reptiles are of interest because the colon and cloaca represent the only sites from which water and ions can be reclaimed from the urine secreted by the kidney. For animals occupying desiccating environments (e.g., deserts and marine environments), postrenal modification of the urine may directly contribute to the maintenance of hypo‐osmotic body fluids. We compared the morphology and distribution of key proteins in the colon, cloaca, and urogenital ducts of watersnakes from marine (Nerodia clarkii clarkii) and freshwater (Nerodia fasciata) habitats. Specifically, we examined the epithelia of each tissue for evidence of mucus production by examining the distribution of mucopolysaccharides, and for evidence of water/ion regulation by examining the distribution of Na⁺/K⁺‐ATPase (NKA), Na⁺/K⁺/Cl^? cotransporter (NKCC), and aquaporin 3 (AQP3). NKCC localized to the basolateral epithelium of the colon, urodeal sphincter, and proctodeum, consistent with a role in secretion of Na⁺, Cl^?, and K⁺ from the tissue, but NKA was not detected in the colon or any compartment of the cloaca. Interestingly, NKA was detected in the basolateral epithelium of the ureters, suggesting the urothelium may play a role in active ion transport. AQP3 was detected in the ureters and coprodeal complex, consistent with a role in urinary and fecal dehydration or, potentially, in the production of the watery component of the mucus secreted by the coprodeal complex. Since no differences in general cloacal morphology, production of mucus, or the distribution of ion transporters/water channels were detected between the two species, cloacal osmoregulation may either be regulated by proteins not examined in this study or may not be responsible for the differential success of N. c. clarkii and N. fasciata in marine habitats. J. Morphol. 2011. © 2011 Wiley Periodicals, Inc.