一种简便的蚤状溞观察方法

蚤状溞(Daphnia pulex)为节肢动物门(Arthropoda)鳃足亚纲(Branchiopoda)动物。分布广泛,常为湖泊池沼的优势种,是鱼类优良的天然饵料。同时,蚤状溞也是一种很好的实验材料。     

温度对透明溞和隆线溞——亚种发育及生长的影响

透明溞（Daphnia hyalina）和隆线溞——亚种（D.carinata ssp.）的发育、生长与温度的关系极为密切。胚胎发育时间随温度升高而缩短。低温培养的个体普遍大于高温。龄期、寿命也随温度升高而变短。     

武汉东湖透明溞和隆线溞一亚种的种群变动和生产量

本文报道了1980—1982年东湖二种优势枝角类:透明溞(Daphnia hyalina)和隆线溞一亚种(Daphnia carinata ssp.)的种群变动和生产量的研究结果。分析了影响种群变动和生产量的生态因子。尽管这二种枝角类在一年中有一段共存时间,但高峰期从来是错开的。一般来说,透明溞的高峰期出现在春季或冬季;而隆线溞一亚种则出现在夏季或秋季源沓ㄋ蘑蛘纠此?1980—1982年透明溞的种群密度的年平均值为28.43(17.59—38.50)个/升;隆线溞一亚种为4.64(3.79—5.31)个/升。种群的瞬时出生率(b),;通常大于瞬时增长率(r);瞬时死亡率(d)与b的季节变动在大多数情况下是一致的。透明溞的年平均生物量为0.218(0.163—0.315)毫克干重/升,生产量为9.181(4.877—13.428)毫克干重/升·年,P/B系数为42.38(27.76—56.70)。隆线溞一亚种的年平均生物量为0.046(0.039—0.060)毫克干重/升,生产量为3.417(2.752—3.829)毫克干重/升·年,P/B系数为77.04(61.24—99.74)。       

基于16S rDNA和COⅠ基因序列探讨四种溞类的系统关系和分类地位

为了检验已记录的4个溞属种类（(隆线溞Daphnia carinata、透明溞D. hyalina、蚤状溞D. pulex和大型溞D. magna）的系统分类, 用试剂盒法分别提取4种溞类的基因组DNA。利用特异性引物, 通过PCR扩增了4种溞属种类的16S rDNA和COⅠ基因部分序列, 并与来自GenBank中每个种类相似度较高的同种序列进行分析。结果表明, 基于16S rDNA和COⅠ基因, 4个溞属种类的平均种间相似度分别为85.56%和80.67%, 碱基中A+T含量均明显高于G+C含量。基于COⅠ基因, 巢湖隆线溞与来自GenBank上的拟同形溞（(Daphnia similoides AB549199）)相似度为99%, 分歧度为0.4%0.9%。就16S rDNA和COⅠ基因而言, 巢湖透明溞更接近于盔形溞（Daphnia galeata）。基于16S rDNA和COⅠ基因构建的NJ树和贝叶斯树, 两者的主要分枝基本一致。结果暗示, 巢湖隆线溞与拟同形溞为一个种, 透明溞应属于盔形溞。由于缺乏核基因的研究, 有关巢湖溞属的分类地位还需进行更深入的探讨。       

富营养水体大型溞(Daphnia magna)的种群数量对浮游植物的控制效应

“非经典生物操纵”治理水体富营养化的手段在我国大量尝试, 结果有成有败, 原因聚焦于水溞作为关键种在水体中的种群数量问题。为研究不同密度溞类对包括水华蓝藻在内的浮游植物群落及其生物多样性的影响, 以蓝藻占优势的富营养型水体作为研究对象, 在实验室可控条件下进行了大型溞的种群密度操纵实验, 设置三个处理组: 对照组 0 个·L–1, 低密度溞 37.5 个·L–1, 高密度溞 125 个·L–1。结果显示, 与对照组相比, 低密度溞和高密度溞添加对浮游植物丰度和生物量具有显著的抑制效应, 表明大型溞对浮游植物的直接滤食效力高于营养盐再循环所产生的间接促进效力,这暗示着Daphnia 的添加对保持水体的清水态具有较好的效果。此外, 高密度溞添加组同时降低了浮游植物群落中蓝藻的比例, 并显著降低了浮游植物生物多样性, 使一些可以逃避Daphnia 捕食的大个体藻类(针杆藻)得以发展, 这暗示着Daphnia 对水华蓝藻的发生具有一定的抑制效应的同时, 过高密度的Daphnia 对浮游植物生物多样性的保持不利。     

武汉东湖透明溞和隆线溞——亚种体长-体重回归方程式

透明溞(Daphnia hyalina)和隆线溞-亚种(Oaphnia carinata ssp.)是东湖优势枝角类。作者采用直接称重法,测定了这两种枝角类不同体长组的鲜重、干重,和保存于4％福马林溶液中的标本的湿重、干重,并应用统计方法获得了相应的体长-体重回归方程式。并与前人发表的公式作了比较;同时对干重和湿重的百分比作了扼要的讨论。     

太湖梅梁湾沉积物中溞属卵鞍的垂直分布及其与总氮、总磷间的关系

本研究调查了太湖梅梁湾沉积物(25~1 cm)中溞属种类卵鞍(或休眠卵)的垂直分布及其与总氮、总磷的关系。结果表明:在梅梁湾的沉积物中,共鉴定出3种溞属种类(盔形溞(Daphnia galeata)、蚤状溞(Daphnia pulex)和中华拟同形溞(Daphnia similoides sinensis))的卵鞍,其中以盔形溞为优势种;溞属种类平均卵鞍密度及含休眠卵卵鞍密度分别为0.03~2.01和0~0.33 ind·g-1dw;T1和T2采样点的3种溞属种类的含休眠卵卵鞍密度明显高于T3采样点;在16~1 cm的沉积层中,T1采样点的总氮和T2采样点的总磷均呈明显增加的趋势,而T3采样点中的总氮和总磷变化幅度均较小;T1采样点中蚤状溞的卵鞍密度与总磷(TP)含量呈显著的相关性(P0.05),而T3采样点中中华拟同形溞的卵鞍密度和T2采样点中盔形溞的含休眠卵卵鞍密度与总氮(TN)总磷(TP)含量均呈显著的相关性(P0.05);湖泊沉积物中溞属种类的卵鞍(或休眠卵)密度的垂直分布能够再现湖泊溞属种类的历史演替过程,且与总氮、总磷含量之间存在一定的相关性。     

温度及pH对隆线溞生长和生殖的影响

研究了隆线溞(Daphnia carinata)在不同温度(15、20、25、30℃)和pH(6、7、8、9、10)影响下的内禀增长率(rm)、周限增长率(λ)、平均世代周期(T)、净生殖率(R0)、平均寿命、第一怀卵日、平均生殖间隔期和总生殖量.结果表明,温度对隆线溞的生命参数有显著影响,30℃组的内禀增长率(rm)...     

温度对透明溞和隆线溞一亚种发育及生长的影响

透明溞(Daphnia hyalina)和隆线溞一亚种(D. carinata ssp.)的发育、生长与温度的关系极为密切。胚胎发育时间随温度升高而缩短。低温培养的个体普遍大于高温。龄期、寿命也随温度升高而变短。在15—30℃温度范围内,实验种群的内禀增长力(rm)随温度升高而增加。透明溞的产卵率以20℃为最高,达1.4936;而隆线溞一亚种则在15℃为最高,达1.490。不同种类在各种温度下,卵一胚胎,幼体,成体3个发育阶段所需时间的百分比变化甚小。卵一胚胎占总发育时间(从卵进入孵育囊起至成体死亡止)的(5.08±0.42)%,幼体为(10.76±1.53)%,成体为(84.16+1.72)%。根据不同温度下总胚胎发育时间,并参考了文献中记载的资料,获得了溞属温度与总胚胎发育时间的曲线迥归方程: Ln D=3.5748+0.0769 LnT-0.3122(Ln T)2对隆线溞一亚种的形态、生态进行了描述,对它的分类地位进行了讨论。       

六六六对大型溞生态学的影响

在实验室条件下,测定了六六六对大型溞(Daphnia magna Straus)存活、生长和生殖的影响。在25℃时,以心跳停止为死亡标准,六六六(以丙体计)对大型溞48小时LC50及其95%可信限为1.32±0.30ppm。以存活、生长和生殖为毒性标准,未觉察反应浓度(NOEC)为150ppb,最低觉察反应浓度(LOEC)为200ppb,其应用因子在0.11-0.15之间。内禀增长能力(rm)是更为敏感的指标,六六六浓度要降低至50ppb才无明显影响。       

Ester production in E. coli and C. acetobutylicum

Genetic engineering has improved the product yield of a variety of compounds by overexpressing, inactivating, or introducing new genes in microbial systems. The production of flavor-enhancing ester compounds is an emerging area of heterologous gene expression for desired product yield in Escherichia coli. Isoamyl acetate, butyl acetate, ethyl acetate, and butyl butyrate are reported here to be produced by expressing Saccharomyces cerevisiae genes ATF1 or ATF2 and the strawberry gene SAAT in E. coli when the appropriate substrates are provided. Increasing the concentration of alcohol added to the reaction generally resulted in increased ester production. ATF1 expression was found to produce more isoamyl acetate and butyl acetate than ATF2 expression or SAAT expression in the strains and culture conditions examined. Additionally, SAAT expression resulted in greater isoamyl acetate and butyl acetate production than ATF2 expression. Butyl butyrate is produced by cell-free extracts of E. coli harboring SAAT but not ATF1 or ATF2.     

豹纹鳃棘鲈体色变异的色素细胞差异分析

为了揭示豹纹鳃棘鲈(Plectropomus leopardus)体色变异机制, 研究选取了不同体色个体的样本, 利用石蜡切片、冰冻切片及体视显微镜观察等方法揭示不同皮肤部位色素细胞的类型、分布和数量的差异, 并对应激和非应激状态下色素细胞的变化进行了研究。结果显示, 黑色素细胞在背部和尾部分布比较密集, 在腹部较为稀疏, 黑色个体的黑色素细胞数量较红色个体多; 在应激状态下个体能迅速发生体色变化, 主要由于色素细胞快速扩张和收缩导致。研究为进一步揭示豹纹鳃棘鲈体色变异的分子机制和优良品种选育奠定了基础。     

Quinua and Relatives (Chenopodium sect.Chenopodium subsect.Celluloid)

Traditionally viewed as an Andean grain crop,Chenopodium quinoa Willd. includes domesticated populations that are not Andean, and Andean populations that are not domesticated. Comparative analysis of leaf morphology and allozyme frequencies have demonstrated that Andean populations, both domesticated(quinua) and free-living(ajara), represent an exceptionally homogeneous unit that is well differentiated from allied domesticates of coastal Chile(quingua) and freeliving populations of the Argentine lowlands(C. hircinum). This pattern of relationships indicates that Andean populations represent a monophyletic crop/weed system that has possibly developed through cyclic differentiation (natural vs. human selection) and introgressive hybridization. Relative levels of variation suggest that this complex originated in the southern Andes, possibly from wild types allied withC. hircinum, with subsequent dispersal north to Colombia and south to the Chilean coast. Coastal populations were apparently isolated from post-dispersal differentiation and homogenization that occurred in the Andes. Other data point toward a center of origin in the northern Andes with secondary centers of genetic diversity subsequently developing in the southern Andes and the plains of Argentina. Comparative linkage of South American taxa, all tetraploid, with North American tetraploids of the subsection will eventually clarify this problem. While the possibility of a direct phyletic connection betweenC. quinoa and the Mexican domesticate(C. berlandieri subsp. nuttalliae,) cannot be excluded, available evidence indicates that the latter represents an autonomous lineage that is associated with the basal tetraploid, C. b. subsp.berlandieri, through var.sinuatum, whereas South American taxa show possible affinities to either var. zschackei or var.berlandieri. An extinct domesticate of eastern North America,C. b. subsp.jonesianum, represents either another instance of independent domestication, possibly from subsp. b. var.zschackei, or a northeastern outlier of subsp.nuttalliae.     

两种广西特有报春苣苔属(苦苣苔科)植物传粉生物学研究

通过野外观察和室内试验,对两种广西特有的桂林小花苣苔和阳朔小花苣苔的传粉生物学进行比较研究。结果表明:两种报春苣苔属植物花期从7月底至8月初;单花花期内花粉具有较高的活性,最高可达92.6%和94.5%;柱头可授性最高时可达90%和95%;花粉/胚珠比率(P/O)分别为110.28±17.45和229.65±18.00;柱头与花药之间存在着空间隔离,可防止自花授粉;在单花花冠裂片张开后第3天,花药开始散粉,但雌蕊在花朵刚开始开放时已伸长,待第3天时柱头已伸长到位于花冠筒口部,高于花药,便于接受异花花粉;该两种植物均不存在无融合生殖现象;两种报春巨苔属植物均高度自交亲和,但很难发生自发的自花授粉,必须依靠外力,因此传粉媒介对于结实率有重要影响,自然条件下基本不发生自花授粉;在自然状态下结实率明显低于两种人工授粉的结实率;小蜂和淡脉隧蜂是目前已知仅见的两种传粉者。     

Presence of Rhizobium Etli bv . Phaseoli and Rhizobium Gallicum bv . Gallicum in Egyptian Soils

Seven bean rhizobial strains EBRI 2, 3, 21, 24, 26, 27 and 29 identified as Rhizobium etli, and EBRI 32 identified as Rhizobium gallicum, isolated from Egyptian soils and which nodulated Phaseolus vulgaris efficiently, were subjected to hybridization with a nifH probe in order to estimate the copy number of this gene. Seven strains (EBRI 2, 3, 21, 24, 26, 27 and 29) which were only able to nodulate Phaseolus vulgaris, contained three copies of the nifH gene, consistent with their identification as Rhizobium etli bv. phaseoli. Only one strain (EBRI 32) which nodulated both Phaseolus vulgaris and Leucaena leucocephala, had one copy of nifH gene. This confirmed the classification of this strain as Rhizobium gallicum bv. gallicum.     

阿根廷滑柔鱼年间生长及体征变化

阿根廷滑柔鱼(Illex argentinus)的生长发育及体征变化, 可表征其能量积累和生殖投入方面的生活史策略, 并随之影响繁殖成效和资源补充量。为此, 研究根据2012—2014年在西南大西洋索饵育肥场采集的阿根廷滑柔鱼样本, 采用残差指标分析方法和广义线性混合效应模型, 分析了阿根廷滑柔鱼个体的体质量-胴长关系和体征变化的差异性。结果显示, 阿根廷滑柔鱼样本的总体雌雄比例为1.25﹕1; 雌性和雄性个体体型均以2014年的为最大, 分别为(271.7±28.3)和(244.7±17.3) mm; 2012年和2013年样本的胴长差异性不显著, 前者雌性和雄性胴长分别为(207.9±31.0)和(201.1±28.9) mm, 后者雌性和雄性胴长分别为(213.6±18.0)和(203.5±19.0) mm。每个年份雌性和雄性个体的体质量与胴长呈显著的幂函数关系, 且每个年份幂函数关系式的b值与匀速生长b=3存在差异。雌性和雄性个体体征的年间差异明显, 同年度不同月份之间的体征亦存在显著差异(2012年雌性除外)。雌性和雄性个体的体征与胴长密切相关, 胴长×月份作用对不同月份个体体征的影响效应具有一致性, 即个体越大体征较差。以上结果表明, 阿根廷滑柔鱼的生长为异速生长, 体征存在年间和月份差异性, 体征与胴长呈显著的负相关关系。     

Genome constitutions of Pseudoroegneriageniculata, P. geniculata ssp. scythica and P. geniculata ssp. pruinifera (Poaceae: Triticeae) revealed by genomic in situ hybridization

Genomic constitutions of three taxa of Pseudoroegneria á. L?ve, P. geniculata, P. geniculata ssp. scythica, and P. geniculata ssp. pruinifera, were characterized using genomic in situ hybridization (GISH). The results indicated that ploidy level and genomic constitution in the three Pseudoroegneria taxa studied were as follows: P. geniculata (2n = 4x = 28; genomic formula StSt ^g ), P. geniculata ssp. scythica (2n = 4x = 28; genomic formula ESt), and P. geniculata ssp. pruinifera (2n = 6x = 42; genomic formula EESt). P. geniculata ssp. scythica and P. geniculata ssp. pruinifera should be transferred to Trichopyrum á. L?ve following L?ve’s principles and treated as T. scythicum and T. pruiniferum, respectively.     

Cardenolides from Asclepias asperula subsp. Capricornu and A. Viridis

6′-O-(E-4-hydroxycinnamoyl) Desglucouzarin, the first cardenolide containing a cinnamoyl ester moiety, has been isolated from the ethanolic extract of the milkweed, Asclepias asperula. In addition, five known cardenolides were isolated and identified from A. asperula and A. viridis.     

应恢复赤车属头序赤车组和头序赤车

头序赤车的特征在于其具花序托和总苞的雌头状花序,根据此一特征即可将它与赤车属的其它所有种区别开.因此,在2002年被错误归并为异名的此赤车属进化种,以及根据其建立的单种进化组头序赤车组在该文中予以恢复.