温度对矩形龟甲轮虫生命表统计学参数和形态特征的影响

应用单个体培养方法研究了温度(10℃、15℃、20℃和25℃)对双后棘刺、单后棘刺和无后棘刺矩形龟甲轮虫的净生殖率、内禀增长率、世代时间、平均寿命和后代混交率等生命表统计学参数以及后代体长、体宽、前中棘刺长、左右两前侧棘刺长、左右两后棘刺长、后棘刺数目等形态参数的影响.结果表明,各生命表统计学参数和后代形态参数在3种形态型轮虫间的差异因温度的不同而异,它们对温度升高的反应也因轮虫形态型的不同而异.温度显著影响轮虫的内禀增长率、世代时间、平均寿命和后代所有的形态参数(P＜0.05);形态型显著影响轮虫后代的体长、前中棘刺长和左右两后棘刺长(P＜0.05),但对轮虫的生命表统计学参数均无显著影响(P＞0.05);而温度和形态型的交互作用显著影响轮虫的世代时间和后代的形态参数(P＜0.05).3种形态型轮虫间,双后棘刺轮虫后代的体长(122.1±0.6μm)显著短于无后棘刺和单后棘刺轮虫后代的体长(分别为126.3±0.7μm和125.1±0.7 μm),前中棘刺长(32.5±0.3 μm)显著长于无后棘刺和单后棘刺轮虫后代的前中棘刺长(分别为31.l±0.3μm和30.8±0.3μm),左后棘刺长(31.2±1.0μm)和右后棘刺长(32.3±0.9 μm)均与单后棘刺轮虫后代的(分别为29.5±0.8 μm和31.5±0.6 μm)相似,但显著短于无后棘刺轮虫后代(分别为36.7±1.5 μm和37.3±1.6μm).矩形龟甲轮虫后代的棘刺长、体宽和体长之间的关系也受温度和形态型的影响.     

萼花臂尾轮虫多态性及形态型转化

在实验室条件下研究了萼花臂尾轮虫3种形态型(双短侧棘刺、单短侧棘刺和无侧棘刺)个体之间的关系。从轮虫的培养水体中随机挑出若干3种形态型雌体的幼轮虫(龄长<24 h)，分别培养在正常培养液和晶囊轮虫培养液过滤液中。将实验轮虫的后代(F1代)置于200倍显微镜下检查其个体的形态型。实验结果表明，在正常培养液中，每种形态型轮虫个体都可以产生3种形态型的后代。当培养在晶囊轮虫培养液过滤液中时，这3种形态型轮虫的后代都具有2个显著增长的侧棘刺。此外，这3种形态型个体的轮虫能够共存于同一培养环境中，而且每种形态型个体的轮虫都具有3种生殖类型的雌体。由此推测萼花臂尾轮虫是一个由3种基础形态型个体组成的形态型轮虫复合体。     

萼花臂尾轮虫多态性及形态型转化

在实验室条件下研究了萼花臂尾轮虫3种形态型(双短侧棘刺、单短侧棘刺和无侧棘刺)个体之间的关系。从轮虫的培养水体中随机挑出若干3种形态型雌体的幼轮虫(龄长<24h),分别培养在正常培养液和晶囊轮虫培养液过滤液中。将实验轮虫的后代(F1代)置于200倍显微镜下检查其个体的形态型。实验结果表明,在正常培养液中,每种形态型轮虫个体都可以产生3种形态型的后代。当培养在晶囊轮虫培养液过滤液中时,这3种形态型轮虫的后代都具有2个显著增长的侧棘刺。此外,这3种形态型个体的轮虫能够共存于同一培养环境中,而且每种形态型个体的轮虫都具有3种生殖类型的雌体。由此推测萼花臂尾轮虫是一个由3种基础形态型个体组成的形态型轮虫复合体。     

汀棠湖轮虫主要食性功能群及其优势种群的周年动态对水环境变化的响应

为探讨轻度富营养湖泊中轮虫主要食性功能群及其优势种群的动态对水环境响应的生态机理,于2011年7月至2012年6月每月4次采集了芜湖市汀棠湖水体中的浮游动物样品,同步测定了水温、水体透明度、p H值、水体叶绿素a含量和氮磷含量,利用相关分析和多元线性回归分析方法分析了轮虫主要食性功能群及其优势种群的密度与非生物因子(如水温等)、食物资源(以粒径大小不同的藻类中的叶绿素a含量作为指标)及生物因子(枝角类、桡足类和晶囊轮虫等轮虫潜在竞争者和捕食者的密度)间的关系。结果显示:(1)汀棠湖中,掠食性轮虫的优势轮虫为针簇多肢轮虫(Polyarthra trigla);滤食性轮虫的优势种包括裂足臂尾轮虫(Brachionus diversicornis)、长三肢轮虫(Filinia longiseta)和裂痕龟纹轮虫(Anuraeopsis fissa);(2)主成分分析表明,水温、叶绿素a含量、枝角类、桡足类及其无节幼体和晶囊轮虫的密度是影响与汀塘湖轮虫群落结构有关的变动最大的水环境因子。水温和藻类叶绿素a总含量分别对滤食性轮虫和掠食性轮虫总密度的周年变动的影响最大,而轮虫的潜在竞争者和捕食者对它们的负面影响均不大;(3)轮虫的潜在竞争者和捕食者对于轮虫优势种群密度动态的负面影响也不大。水温、藻类叶绿素a总含量及小型藻类叶绿素a含量(经孔径为25μm的筛绢过滤后水样中的叶绿素a含量(Chl-a25μm))均与滤食性裂足臂尾轮虫和长三肢轮虫的密度间呈现显著或极显著的正相关关系。仅小型藻类的叶绿素a含量对裂足臂尾轮虫和长三肢轮虫密度的周年变动的影响最大。水温是影响滤食性裂痕龟纹轮虫密度动态的主要因子;(4)两食性功能群中的优势轮虫种群的卵率均未与其潜在竞争者和捕食者密度间呈现显著的负相关性。裂足臂尾轮虫、长三肢轮虫和针簇多肢轮虫种群卵率的变动受水温的影响最大,且它们之间均分别呈现显著的负相关性。研究结果表明,水温和食物资源可能是影响汀塘湖中滤食性轮虫和掠食性轮虫密度变动的重要的生态因子。     

镜湖夏秋季节裂足臂尾轮虫卵率变化及影响因素

调查了安徽省芜湖市镜湖中裂足臂尾轮虫的卵率,分析了卵率与种群密度、食物资源、潜在捕食者和竞争者、水温、水体透明度、溶氧、pH以及氨氮浓度等之间的关系。结果表明,大湖区中,裂足臂尾轮虫的卵率在0.095-1.073间变动,均值为0.293;卵率与种群密度和透明度呈显著的负相关(r值分别为-0.346和-0.329),与总叶绿素a含量和直径小于25μm的藻类叶绿素a含量均呈显著的正相关(r值分别为0.457和0.417);异尾轮虫密度对裂足臂尾轮虫卵率的影响具有明显的时滞效应(r=0.382);在晶囊轮虫密度高峰期,其密度是影响卵率的最主要因素(R2=0.5074)。小湖区中,裂足臂尾轮虫的卵率在0.0471-0.5455间变动,均值为0.194;卵率只与总叶绿素a含量呈显著的正相关(r=0.356)。研究结果提示影响裂足臂尾轮虫卵率的因素具有时空异质性。     

镜湖常见臂尾轮虫(Brachionus)种群周年动态及生活史对策

对镜湖臂尾轮虫种群的周年动态进行了研究,测量和分析了它们的个体大小、卵大小和相对卵大小及其与水温和叶绿素a浓度等生态因子间的关系。结果表明,镜湖常见的7种臂尾轮虫中,仅萼花臂尾轮虫(Brachionus calyciflorus)、角突臂尾轮虫(B.angularis)、裂足臂尾轮虫(B.diversicornis)和剪形臂尾轮虫(B.forficula)的种群密度和出现频率较高;前两者种群密度高峰期均出现在2~3月份,4月份后均较低;后两者种群密度在6~9月份较高,而在10月份后很快下降。除剪形臂尾轮虫外,其它3种臂尾轮虫的个体体积均与水温间具有显著的相关性,平均卵体积均与各自的平均被甲长度呈显著的正相关关系。角突臂尾轮虫和萼花臂尾轮虫个体大小与水体叶绿素a浓度间呈显著的负相关关系,它们的卵体积分别与水温和叶绿素a浓度之间具有显著的负相关性,且水温是影响它们卵体积的主要因子。4种臂尾轮虫中,仅角突臂尾轮虫的相对卵体积与水温间表现出显著的正相关关系。     

芜湖市镜湖轮虫群落结构分析及水质的生态学评价

2003年1—12月,对芜湖市镜湖轮虫群落结构的周年动态进行了研究,并分析了轮虫密度与有关生态因子间的关系。经鉴定,共发现轮虫55种,隶属于15科21属。密度优势种为裂痕龟纹轮虫(Anuraeopsis fissa)、暗小异尾轮虫(Trichocerca pusilla)、前额犀轮虫(Rhinoglena frontalis)、红多肢轮虫(Polyarthra remata)、长三肢轮虫(Filinia longise-ta)、广布多肢轮虫(Polyarthra vulgaris)和多须伪前翼轮虫(Proalides tentaculates),而生物量优势种为前节晶囊轮虫(Asplanchna priodonta)、多须伪前翼轮虫和暗小异尾轮虫。全年轮虫的总密度与水温、叶绿素a浓度及小型纤毛虫密度具有显著的相关性;温度对全年轮虫总密度的影响最大,叶绿素a浓度对春、冬季轮虫总密度影响最大,小型纤毛虫密度对夏季轮虫总密度影响最大,而水温是影响秋季轮虫总密度的主要因素。根据污染指示生物、物种多样性指数和Q值并结合水理化性质对治理后的镜湖水质所进行的初步评价表明,经清淤、截流和换水等措施治理后,小湖区应偏属寡污-β中污至β中污型水体,大湖区属于β中污型水体;目前镜湖水体处于中营养后期—富营养化初期阶段。       

两湖泊轮虫群落结构的时空动态对水体氮磷含量及“下行效应”的响应

为探讨氮和磷、"上行效应"和"下行效应"在轮虫群落结构时空变动调控中的相对重要性,于2011年7月至2012年6月每月两次采集了芜湖市九莲塘和汀棠湖中的轮虫样品,利用相关分析法和典范对应分析法(CCA)分析了轮虫群落结构的时空变动与水体理化因子及其潜在捕食者密度间的关系。卡尔森营养状态指数表明,两湖均处在富营养化初期。除了总氮和硝态氮的年均浓度、晶囊轮虫(Asplanchna)和剑水蚤(Cyclopoidea)无节幼体的年均密度存在显著差异外(P0.05),两湖泊的其他水环境因子间并未表现出明显的差异(P0.05)。实验室鉴定发现九莲塘中共有轮虫48种,隶属于15科21属;汀棠湖中共有轮虫55种,隶属于15科24属。两湖泊中,疣毛轮虫(Synchaeta)、臂尾轮虫(Brachionus)和异尾轮虫(Trichocerca)均是主要轮虫类群,而密度优势种分别有7种和4种。相关分析结果显示,P含量与九莲塘轮虫群落的均匀度和物种多样性指数间均呈现显著的负相关(P0.05),而N含量却与汀棠湖轮虫群落的物种多样性指数呈现显著的正相关(P0.05);两湖泊中的轮虫物种多样性指数均与水体中的TN∶TP(质量比)间呈现显著的正相关(P0.05)。CCA分析结果显示,九莲塘中桡足类和其无节幼体密度显著高于其他采样批次时的轮虫群落聚成Ⅰ类,汀棠湖中晶囊轮虫密度显著高于其他批次时的轮虫群落聚成Ⅱ类,而其他的轮虫潜在捕食者密度很低或未出现时的轮虫群落聚成Ⅲ类。研究结果表明,湖泊中的TN∶TP(质量比)可能是反映N和P含量对轮虫群落物种多样性影响程度的较为合适的指标。当水体中的轮虫潜在捕食者密度较高时,两湖泊轮虫群落结构的变动均主要取决于"下行效应";而当轮虫潜在捕食者密度很低时,"上行效应"可能是调控两湖泊轮虫群落结构变动的主要因素。     

汀棠湖冬季出现的萼花臂尾轮虫对水温的适应

为了解汀棠湖冬季出现的萼花臂尾轮虫对水温的适应,探讨其在春季的种群消长机制,运用生命表统计学方法研究了温度(12℃、16℃、20℃和24℃)和斜生栅藻(Scenedesmus obliquus)密度(1.0×106、3.0×106和5.0×106个/mL)对冬季采自芜湖市汀棠湖水体中的萼花臂尾轮虫(Brachionus calyciflorus)出生时的生命期望、世代时间、平均寿命、总生殖率、净生殖率和种群内禀增长率等生活史参数的影响。结果表明,温度对轮虫出生时的生命期望、世代时间、平均寿命、净生殖率和种群内禀增长率均有显著性影响(P0.05),但对总生殖率无显著性影响(P0.05);食物密度以及食物密度与温度之间的交互作用对轮虫所有生命表统计学参数均无显著性影响(P0.05)。轮虫出生时的生命期望和平均寿命在12℃下较长,16、20℃和24℃下较短且三者间无显著性差异;轮虫的世代时间在12℃下最长,16℃和24℃下最短且两者间无显著性差异;轮虫的净生殖率在16℃下较高,12、20℃和24℃下较低且三者间无显著性差异;轮虫的种群内禀增长率在12℃下最低,16℃下最高,20℃和24℃间无显著性差异。汀棠湖冬季出现的萼花臂尾轮虫在16℃下的适合度最高,这或许是该水体中萼花臂尾轮虫种群密度在3月中旬(此时水温为17℃)达到春季最高峰的重要原因之一。     

萼花臂尾轮虫种复合体内三个姐妹种的形态差异

应用单因子方差分析和判别分析方法,分别比较了采自芜湖市3个自然水体的萼花臂尾轮虫种复合体内3个姐妹种(分别以克隆HE1和HE5、克隆HE3和SE1、克隆LE9为代表)的成体和幼体的形态差异。结果表明,克隆HE3成体的各形态参数均最小,而克隆HE1和LE9成体的各形态参数间无显著的差异;克隆HE1和HE3幼体的前中棘刺间距离和后侧棘刺长度、克隆LE9和HE1幼体的前侧棘刺间距离以及前中棘刺和侧棘刺间距离均无显著性差异,轮虫幼体的其它形态参数均以克隆LE9最长,克隆HE1次之,克隆HE3最短。对克隆HE1、HE3和LE9幼体有明显差异的形态参数所作的分布图显示,它们的分布区有很高程度的重叠。以判别分析建立的判别函数对3姐妹种成体的综合判别率中形态分析Ⅰ为47.8%,形态分析Ⅱ为55.6%;对3姐妹种幼体的综合判别率中形态分析Ⅰ和Ⅱ均为71.1%;两种形态分析对克隆HE1判别准确率均较低,分别为0-76.7%和0-74.2%;依据形态特征无法准确甄别萼花臂尾轮虫姐妹种。     

基于 rDNA ITS 1序列探讨臂尾轮属轮虫的系统发生关系

本文通过对剪形臂尾轮虫、矩形臂尾轮虫、十指臂尾轮虫、红臂尾轮虫、角突臂尾轮虫、双棘臂尾轮虫、裂足臂尾轮虫和萼花臂尾轮虫等八种臂尾轮虫rDNAITS 1序列分析,并以西氏晶囊轮虫为外群,使用PAUP和贝叶斯软件分别构建臂尾轮属轮虫系统发生树( MP树、NJ树、ML树和贝叶斯树) ,以探讨臂尾轮属的系统发生关系,并解决其中的一些分类问题。结果表明:本研究所涉及的轮虫rDNAITS 1平均序列差异百分比较高,为29 %;海水和淡水臂尾轮虫被明显分为不同的进化枝;除双棘臂尾轮虫外,在淡水臂尾轮虫中具有三对前棘刺且营附着生活的种类与前棘刺少于三对且营浮游生活的种类聚在不同支系中,这与以形态特征为主所进行的系统发生研究结果基本一致;所有的系统树均支持将十指臂尾轮虫作为一个独立的支系分离出来,裂足臂尾轮虫应归入臂尾轮属。     

Induction and inhibition of spine development in the rotifer Keratella tropica

1. We analysed the effect of several variables on the morphology of the rotifer Keratella tropica with the aim of accounting for its morphological variability in nature. We used field data from (i) an extensive survey of Argentine lakes, (ii) a 1.5 yr, monthly sampling of Salto Grande Reservoir, and (iii) a 3-month, outdoor experiment in fish culture tanks. In addition, we performed a series of laboratory experiments aimed at isolating the effects of different variables. 2. The increase in crustacean biomass and the amelioration of their nutritional status (measured as the reciprocal of the starvation time) caused spine enlargement. In contrast, the presence of decomposers caused reduction of the spines. These results support the idea that a major proportion of the phenotypic expression of K. tropica depends on the concentration of an inducing factor, which in turn depends on the balance between release and decomposition rates of the chemical. 3. Food concentration was identified as a secondary factor affecting morphology. In agreement with records for other rotifers, food concentration and spine length were inversely related. Both factors, crustacean chemicals and food availability, seemed to act independently, at different developmental stages. Our experiments suggest, however, that the most exuberant individuals can only be induced through chemicals released by predators and competitors. 4. The presence of backswimmers (Notonectidae) resulted in individuals with very short or non-existing posterior spines. Filtrates of backswimmer-conditioned medium also produced a significant, although less striking, spine inhibition. Thus, different chemical factors seem to have opposite effects on K. tropica morphology. Those released by crustaceans induce spine elongation, while those released by backswimmers inhibit spine development. 5. Genetic differences were also identified as a source of morphological variability. Under identical laboratory conditions, different clones had spines of different length. Our experiments also suggest an inverse relationship between spine length and growth rate. The latter result, however, is based upon only three clones of K. tropica and is thus preliminary.     

Morphological variation of <Emphasis Type="Italic">Keratella cochlearis</Emphasis> (Gosse) in Myanmar (Burma) in relation to zooplankton community structure

Keratella cochlearis was present in 27 of 35 water bodies sampled in Myanmar, and was the most abundant rotifer in 10. Measurements of lorica length and posterior spine length from 20 localities showed that posterior spine length varied both with lorica length and with the composition of the crustacean zooplankton. Long spines were associated with dominance by Heliodiaptomus. The shortest spines were found in samples dominated by cladocerans or cyclopoid copepods. Posterior spine length was positively correlated with the number of diaptomid copepods. Forms without posterior spines were found in 17 localities. The lorica lengths of these spineless forms were generally similar to those of co-occurring spined forms (r = 0.68), but in a few samples the loricas of the spineless forms were significantly larger. These larger forms are similar to the ‘aspina’ forms recently recognised in the River Thames in England. These samples were dominated by cladocerans or cyclopoid copepods. In one locality spineless forms were found without spined forms. The crustacean zooplankton in this locality was also dominated by cladocerans. Guest editors: S. S. S. Sarma, R. D. Gulati, R. L. Wallace, S. Nandini, H. J. Dumont & R. Rico-Martínez Advances in Rotifer Research     

Cyclomorphosis in Keratella tropica (Apstein) of Lake Asejire,Nigeria

Of one thousand, one hundred and four (1104), Keratella tropica collected with a 55 m mesh plankton net from the surface of Lake Asejire from February 1974 to February 1976 lorica length and width, and the lengths of the posterior spines were measured.Lake Asejire K. tropica are among the smallest in Africa. Variations in the patterns of spine length development were independent of season as individuals without left posterior spines and with relatively long left and right posterior spines occurred as commonly in the rainy as in the dry season months.Correlations between K. tropica dimensions and thirty environmental factors underscore the importance of physical environmental factors and point to biological and genetic factors as determinants of the patterns of cyclomorphosis in K. tropica.     

Effect of Temperature on Fecundity,Life Span and Morphology of Long‐ and Short‐Spined Clones of Brachionus caudatus f. apsteini (Rotifera)

We investigated the effect of temperature (20, 25 and 30 °C) on fecundity, life span and morphology of the rotifer Brachionus caudatus f. apsteini. For each temperature, short posterior‐spined and long posterior‐spined clones of B. caudatus f. apsteini were individually cultured for up to six generations. The rotifers were fed Chlorella sp. at a density of 1 × 10⁶ cells ml^–1. Morphometric data (body size and spine length) were collected. Total number of offspring producing by a single female per life cycle at high temperature was higher than at low temperature. The duration of juvenile period, reproductive period, post‐reproductive period and life span of both clones of B. caudatus f. apsteini decreased with increasing temperature. All offspring of short posterior‐spined clone produce posterior spines at 20 and 25 °C, with an average length of 19.8 ± 6.6 and 11.9 ± 2.6 μm, respectively. In contrast, they cannot develop posterior spines at 30 °C, at which the average length of the posterior spine remnant was 6.4 ± 1.3 μm. On the other hand, all offspring of long posterior‐spined clone have long posterior spines with average lengths of 36.8 ± 6.1, 36.3 ± 5.2 and 36.6 ± 6.2 μm at 20, 25 and 30 °C, respectively. This study indicated that the production of posterior spines can be induced by low temperature and that short posterior‐spined and long posterior‐spined clones are genetically different. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

镜湖长三肢轮虫的有性生殖

2004年5—11月,对芜湖市镜湖大、小湖区水体中长三肢轮虫(Filinia longiseta)的有性生殖及其与种群密度、水温、水体透明度、水体叶绿素a含量和轮虫总密度等环境因子间的关系进行了研究.结果表明:当水温低于22℃或水体透明度大于一定值(小湖区SD>95cm,大湖区SD>100cm)时,长三肢轮虫不进行有性生殖;而当其本身的种群密度达到一定值(小湖区种群密度>122ind·L-1,大湖区种群密度>113ind·L-1)时才进行有性生殖.长三肢轮虫的混交雌体密度仅与其本身的种群密度以及水体中轮虫总密度之间呈正相关关系(P<0·01),而与水温、叶绿素a含量、水体透明度之间均无明显的相关关系;长三肢轮虫种群的混交率和受精率与水温、水体透明度、叶绿素a含量、轮虫总密度和长三肢轮虫种群密度之间也无明显的相关性.长三肢轮虫的有性生殖发生在种群增长的早期阶段,混交雌体以间断的、多循环的方式产生;最大混交率与最大种群密度同时出现,但最大受精率出现在种群即将消失时.     

Morphological constraints on calcium dependent glutamate receptor trafficking into individual dendritic spine

Glutamate receptor trafficking into dendritic spines is a pivotal step in synaptic plasticity, yet the relevance of plasticity-producing rise of [Ca2+]i and of spine morphology to subsequent delivery of glutamate receptors into dendritic spine heads are still not well understood. Following chemical induction of LTP, an increase in eGFP-GluR1 fluorescence in short but not long dendritic spines of cultured hippocampal neurons was found. Repeated flash photolysis of caged calcium, which produced a transient rise of [Ca2+]i inside spine heads caused a selective, actin and protein synthesis dependent increase of eGFP-GluR1 in these spines. Strikingly, GluR1 increase was correlated with the ability of a calcium transient generated in the spine head to diffuse into the parent dendrite, and inversely correlated with the length of the spine: short spines were more likely to raise GluR1 than long ones. These observations link, for the first time, calcium transients in dendritic spines with spine morphology and its ability to undergo synaptic plasticity.