寄主型和迁飞型棉蚜的交配行为

棉蚜Aphis gossypii Glover种群存在寄主利用和迁飞能力上的明显分化,有棉花型和瓜型、迁飞型和滞留型之分。但是,棉花型与瓜型之间,以及迁飞型与滞留型之间是否能发生交配行为,尚无研究报道。本文在低温和短光照条件下分别诱导棉花型、瓜型、迁飞型和滞留型棉蚜的性蚜,并进行性蚜间的交配行为观察。结果表明,迁飞型和滞留型性蚜间可以发生交配行为,杂交时发生交配行为的个体比率与自交时无显著差异,但是杂交时雄蚜寻找配偶所花的时间要显著长于自交时,并且迁飞型雌蚜(M♀)与滞留型雄蚜(S♂)杂交时的交配持续时间也显著长于自交时。迁飞型和滞留型棉蚜同型交配容易完成,棉蚜的迁飞型和滞留型已在交配行为上产生了一定的分化。棉花型和瓜型棉蚜的性蚜间可以发生交配行为,并且两品系在正交和反交时雄蚜的寻偶时间与交配持续时间均无显著差异。     

戊型肝炎病毒基因1型和基因4型中和表位区域分子差异研究

戊型肝炎病毒(HEV)根据易感宿主的差别可以分为两大类:一类只分离自人的H(Human)类,包括HEV-1和HEV-2;一类为人畜共患的Z(Zoonosis)类,包括HEV-3和HEV-4。本研究通过比较这两类HEV的ORF2aa368~606区段,发现存在4个类保守的差异位点,均位于HEV的主要中和表位区域aa459~606,分别是aa483、aa492、aa497和aa599;对这四个位点进行定点替换突变,以一组能够捕获HEV-1和/或HEV-4的单克隆抗体比较各种突变体的免疫反应性,结果表明仅aa497的差异造成了这两类HEV中和表位构象的部分差异,提示aa497及其相关的病毒表面结构差异在H类和Z类HEV宿主选择中可能扮演重要角色。     

天然型与非天然型脱落酸的生物活性比较

采用新方法精制脱落酸（ＡＢＡ）异构体试样,提高了（Ｓ）－（＋）－ＡＢＡ与（Ｒ）－（－）－ＡＢＡ两对映体纯度。抑制生长试验和残留量分析以及气孔闭合试验表明：天然型（Ｓ）－（＋）－ＡＢＡ活性显著高于非天然型（Ｒ）－（－）－ＡＢＡ或（ＳＲ）－（±）－ＡＢＡ。抑制莴苣种子发芽５０％的活性强度,（Ｓ）－（＋）－ＡＢＡ约是（Ｒ）－（－）－ＡＢＡ的５倍,（ＳＲ）－（±）－ＡＢＡ介于两者之间。抑制萝卜下胚轴生长试验,最显著有效期为２～６ｄ,生理作用期约为一周,（Ｓ）－（＋）－ＡＢＡ活性是（Ｒ）－（一）－ＡＢＡ的３．５倍。鸭跖革气孔闭合试验,（Ｓ）－（＋）－ＡＢＡ活性比（Ｒ）－（－）－ＡＢＡ高１倍。     

C型凝集素

C型凝集素（C-type lectin）代表一个识别碳水化合物配体依赖于钙离子（Ca2＋）参与的糖原结合蛋白家族,含有一个或多个一级结构和二级结构同源的碳水化合物识别结构域。随着研究的深入,越来越多的C型凝集素能够识别体内的非糖类的配体,包括蛋白质和脂类等。这些C型凝集素在维持机体稳态、免疫防御以及免疫监视等重要生理病理过程中发挥着重要作用。就C型凝集素的结构、分类和在免疫系统中的功能作一介绍。     

小麦D^2型与K型,V型,T型细胞质雄性不育系线粒体DNA的RAPD比较分析

采用ＲＡＰＤ方法比较新育成的小麦（ＴｒｉｔｉｃｕｍａｅｓｔｉｖｕｍＬ．）Ｄ２型不育系ｍｓＤ２ＣＡ８０５７与Ｋ型、Ｖ型和Ｔ型细胞质雄性不育系的线粒体ＤＮＡ（ｍｔＤＮＡ）。结果表明,ｍｓＤ２ＣＡ８０５７的ｍｔＤＮＡ不同于其它３种类型不育系,而其它类型不育系的ｍｔＤＮＡ彼此也各不相同。这一结果从分子水平上为鉴定该Ｄ２不育系的不育类型提供了证据。实验还发现在胞质来源相同而核背景不同的Ｔ型不育系间存在线粒体基因组多态性,这是关于小麦中Ｔ型不育系ｍｔＤＮＡ在常规回交转育过程中发生变异的直接证据。这种变异在很大程度上可能是受不同核背景影响的结果。     

沙田柚染色体组型及Giemsa带型分析

本文以沙田柚为材料,对其染色体组型及带型进行了观察分析。组型分析:染色体数目2n=18,根据染色体的相对长度分成大小染色体两种类型,前者包括1、2、3、4和5对,后者为6、7、8和9对,根据臂比,9对染色体能够被分成中部着丝点和近中着丝点染色体两种类型。即第5、7,9对为亚中部着丝点,其余为中部着丝点,第6对染色体上有随体;Giemsa带型:除第二对染色体只显中间带外,其余都显着丝点带,并在3、4、8对染色体短臂上和2、3、1对染色体长臂上均显端带,第2、3,6对同源染色体之间的C带显示杂合性。     

洄游型、淡水型和陆封型刀鲚的寄生蠕虫群落结构

由于对淡水环境的适应和江湖阻隔,部分洄游型刀鲚(Coilia nasus)分化成淡水型和陆封型,为寻找区分洄游型、淡水型和陆封型这3种生态型刀鲚的寄生虫标志,并分析其寄生蠕虫群落结构特征,本文调查了3种生态型刀鲚鳃部、胃、肠和幽门盲囊中寄生蠕虫的种类和感染情况。共发现10种寄生虫,包括鳃上3种单殖吸虫:林氏异钩铗虫(Heteromazocraes lingmueni)、细长嗜鳀虫(Helciferus tenuis)和长江中华钩铗虫(Sinomazocraes changjiangensis);胃部1种复殖吸虫:鲚套茎吸虫(Elytrophallus coiliae);肠道3种线虫:简单异尖线虫(Anisakis simplex)、对盲囊线虫(Contracaecum sp.)和胃瘤线虫(Eustrongylides sp.),以及肠和幽门盲囊的3种棘头虫:陈氏刺棘虫(Acanthosentis cheni)、鲇异吻钩棘头虫(Arhythmacanthus parasiluri)、长江傲刺棘头虫(Brentisentis yangtzensis)。林氏异钩铗虫和陈氏刺棘虫在3种生态型的刀鲚中都有较高的感染率和平均丰度;海水性寄生虫细长嗜鳀虫、鲚套茎吸虫和对盲囊线虫只感染洄游型刀鲚,可作为区分洄游型刀鲚的寄生虫标志;淡水性寄生虫长江中华钩铗虫、鲇异吻钩棘头虫和长江傲刺棘头虫只在淡水型刀鲚中发现,可作为淡水型刀鲚的寄生虫标志。洄游型刀鲚的物种丰富度和Brillouin多样性最高,分别在1.25和0.19以上,淡水型刀鲚的较低,分别为0.79~1.12和0.10~0.12,陆封型刀鲚的最低,分别在0.66和0.02以下,这主要是由于淡水型和陆封型刀鲚中海水性寄生虫大部分丢失,以及淡水性寄生虫感染率和平均丰度都较低造成的。盐度降低和中间宿主缺乏是导致淡水型和陆封型刀鲚中海水性寄生虫丢失的主要原因;而淡水性寄生虫较低的感染水平可能是由于其对新宿主的适应时间较短;地理隔离可能是陆封型刀鲚中寄生虫群落多样性最低的另一重要原因。     

Eltor型霍乱弧菌L型的诱导及形态学观察

本文主要介绍Eltor型霍乱弧菌在液体和固相的青霉素诱导下形成L型的过程及其菌落和菌体的形态学改变。Eltor型霍乱弧菌在被诱导3—5次即可出现典型的L型菌落。本试验共诱导10次,获得稳定的L型菌株,菌落形态除油煎蛋样外,还可见到双重心样菌落、靶环样菌落、纤维型菌落。菌体的正常状态为徽弧状,经青霉素作用后,微弧状消失,膨大变直,继尔变成杆状和杆状长链。菌落中心多为相互盘绕、交织成网状的丝状体。     

两性型天然雌核发育彭泽鲫染色体组型的研究

彭泽鲫是一种两性型天然雌核发育群体。染色体组型分析结果表明：雌、雄鱼的染色体数目均为１６６。它们的核型组成是：３２条中部着丝点染色体、４０条亚中部着丝点染色体、１８条亚端部着丝点染色体和７６条端部着丝点染色体。臂数（ＮＦ）为２３８。本研究结果与其它雌核发育类型的鲫鱼有明显的差别。     

日本鳗鲡的C-型和G-型溶菌酶研究

研究以日本鳗鲡(Anguilla japonica Temminck et Schlegel)为研究对象, 根据其基因组数据库, 预测并扩增出2类, 共5个溶菌酶基因, 包括1个C-型溶菌酶和4个G-型溶菌酶, 分别命名为AJLysC、AJLysG1、AJLysG2、AJLysG3和AJLysG4。它们的cDNA全长分别为811、749、1352、1175和733 bp, 编码143、193、185、185和187个氨基酸。SignalP预测表明, AJLysC和AJLysG1的N-端分别包括15和19氨基酸的信号肽, 另外3种溶菌酶没有信号肽。基因组分析显示, AJLysC、AJLysG2、AJLysG3和AJLysG4的基因结构与其他鱼类的同类溶菌酶的基因结构相似, C-型溶菌酶具有4个外显子, G-型则具有5个。但是, AJLysG1的基因结构与其他鱼类G-型溶菌酶不同, 具有6个外显子, 与其他鱼类溶菌酶的蛋白序列比较, 发现AJLysG1缺失其他G-型溶菌酶存在的第2个酶活性位点氨基酸, 即天冬氨酸Asp。AJLysC与其他很多物种的C-型溶菌酶具有较高的同一性, 如与牙鲆的同一性为72.7%。G-型溶菌酶中AJLysG2、AJLysG3、AJLysG4彼此之间以及与其他物种G-型溶菌酶的同一性相对较高; 而AJLysG1与其他物种以及与其他3种G-型溶菌酶的同一性均不高, 且都在50%以下。组织表达分析显示, 所有5个溶菌酶基因在12种检测的组织中均有表达。C-型溶菌酶在胃及免疫相关组织的表达量较高; G-型溶菌酶在各组织/器官中的表达则差异较大, AJLysG1在皮肤和肌肉中的表达量最高, AJLysG2在免疫组织/器官如血液、头肾、体肾和鳃中表达量较高。经迟缓爱德华氏菌(Edwardsiella tarda)刺激48h后, 这5个溶菌酶基因在组织/器官中的表达量均有上调, 其中在血液、肠道和头肾等的上调较为显著。此外, 研究尝试重组表达这些抗菌肽, 获得了AJLysG2、AJLysG3和AJLysG4基因在鲤上皮瘤细胞(Epithelioma papulosum cyprinid, EPC)细胞中的表达, 重组蛋白表现出对溶壁微球菌(Micrococcus lyso-deikticus)生长的明显抑制作用。文章较全面地研究了日本鳗鲡溶菌酶基因的组成和类型及其表达变化, 并重组表达了部分基因, 这为进一步研究这些溶菌酶的功能, 特别是对病原微生物的作用奠定了基础。     

玉斑锦蛇的染色体组型与Ag—NORs

本文研究的玉斑锦蛇２ｎ＝３８（６Ｍ＋２ＳＭ＋２ＳＴ＋４Ｔ＋２２ｍ＋ＺＷ）,ＮＦ＝５０,Ｎｏ,４为性染色体。ＮＯＲｓ位于Ｎｏ．２长臂末端区,呈现异态。     

不同地理区域鲫鱼染色体银染核仁组织者的比较研究

本文对不同地理区域的鲫鱼(Carassius auratus)—滇池高背鲫、低背鲫、方正银鲫(C.auratusgibelio)的核型及核仁组织者NORs进行了比较研究,并对高背鲫来源作些初步探讨,结果如下: 1.低背鲫Carassius auratus (back low type):2n=100,22m+30sm+48t.st,NORs=4,出现于第5—6对亚中着丝粒染色体短臂。 2.滇池高背鲫Carassius auratus(back high type):2n=156,30m+46sm+80t.st,NORs=6,出现于第5—7对亚中着丝粒染色体短臂。 3.方正银鲫C.auratus gibelio:2n=162,32m+52sm+78t.st NORs=4,出现于第5—6对亚中着粒染色体短臂。     

棕黑锦蛇赤峰亚种染色体组型、C带和Ag-NORs研究

以骨髓细胞为材料研究了棕黑锦蛇赤峰亚种的染色体, 结果表明,该物种的2n=36,由8对大型的和10对微小的染色体组成,AF=50。No.4为性染色体(ZW型);所有大型染色体均显示端粒深染C带,但仅NO.2、3、5和Z染色体显示着丝粒浅染C带。W染色体为整条C带阳性;该物种一对NOR分布于微小染色体。锦蛇属核型可能经历过染色体间的着丝粒融合的罗伯逊易位。 Abstract:This paper reports the karyotype,C-bands and Ag-NORs of Elaphe schrenckii anomala(Boulenger).The diploid number,2n=36,comprising 8 pairs of macro- and 10 pairs of microchromosomes in the E.s.anomala.AF=50.The No.4 is sex chromosome,which belong to ZW type.The C-banding technique revealed telomeric constitutive heterochromatin in the whole macrochromosome.But the centromeric C band was only observed in No.2,3,5 and Z chromosome,while a whole W chromosome is constitutive heterochromatinization.Two NORs was observed in group of microchromosome.     

Occurrence of ZZ/ZW sex chromosomes in <Emphasis Type="Italic">Thoracocharax stellatus</Emphasis> fish (Characiformes,Gasteropelecidae) from the Araguaia River,South America

The karyotypic and chromosomal characteristics of the hatchetfish Thoracocharax stellatus from the Araguaia River, Brazil (Araguaia-Tocantins basin) were analyzed using Giemsa, AgNO(3), and CMA(3) fluorescent staining, and C-banding. The diploid chromosome number was 54 and the karyotypes of females and males were composed of six metacentrics, six submetacentrics, six subtelocentrics and 36 acrocentrics. Two unpaired acrocentric chromosomes were detected in the female karyotype. C-banding showed heterochromatic blocks at several chromosomes and an entirely heterochromatic acrocentric chromosome in females that was lacking in the male karyotype. This discovery indicated a heteromorphic sex chromosome system of the ZZ/ZW type. Ag-staining and CMA(3) fluorescence revealed one major chromosome pair bearing the NORs with the presence of additional signals in some metaphases. Both heterochromatic segments associated with Ag-NORs and the W chromosome were positively stained by CMA(3). Considering the present data and previous findings it is hypothesized that the occurrence of ZW sex chromosome system is widespread in the genus Thoracocharax.     

Mapping of the nucleolus organizer region on chromosome 4 inArabidopsis thaliana

InArabidopsis thaliana the ribosomal RNA genes (rRNA genes or rDNA) are clustered in tandemly repeated blocks in two nucleolus organizer regions (NORs). Cytogenetic analysis has shown that the NORs are localized on chromosome 2 (NOR 2) and 4 (NOR 4). Recently the map position of NOR 2 was determined using a RFLP which was larger than 100 kb. In the course of a fingerprint analysis of differentArabidopsis ecotypes we have detected four rDNA polymorphisms between the ecotypes Landsberg (La) and Niederzenz (Nd). Mapping of these polymorphisms using established segregating F₂ populations reveals that all polymorphisms detected are dominant. Three of them map to the locus on the second chromosome that has been shown to harbour the NOR 2. The fourth polymorphism can be unambigously assigned to the upper arm of the fourth chromosome. This is the first polymorphism found which originates in the second rDNA cluster ofArabidopsis thaliana. It enables localization of NOR 4 and thus completes the mapping of rDNA genes in the NORs ofArabidopsis.     

Mapping of the nucleolus organizer region on chromosome 4 inArabidopsis thaliana

InArabidopsis thaliana the ribosomal RNA genes (rRNA genes or rDNA) are clustered in tandemly repeated blocks in two nucleolus organizer regions (NORs). Cytogenetic analysis has shown that the NORs are localized on chromosome 2 (NOR 2) and 4 (NOR 4). Recently the map position of NOR 2 was determined using a RFLP which was larger than 100 kb. In the course of a fingerprint analysis of differentArabidopsis ecotypes we have detected four rDNA polymorphisms between the ecotypes Landsberg (La) and Niederzenz (Nd). Mapping of these polymorphisms using established segregating F₂ populations reveals that all polymorphisms detected are dominant. Three of them map to the locus on the second chromosome that has been shown to harbour the NOR 2. The fourth polymorphism can be unambigously assigned to the upper arm of the fourth chromosome. This is the first polymorphism found which originates in the second rDNA cluster ofArabidopsis thaliana. It enables localization of NOR 4 and thus completes the mapping of rDNA genes in the NORs ofArabidopsis.     

Chromosomal characterization of two species of genus <Emphasis Type="Italic">Steatogenys</Emphasis> (Gymnotiformes: Rhamphichthyoidea: Steatogenini) from the Amazon basin: sex chromosomes and correlations with Gymnotiformes phylogeny

Gymnotiformes are an important component of the Neotropical ichthyofauna and they are known for their ability to generate and detect electrical discharges. Phylogenetic relationships of Gymnotiformes are still not well understood. However, the monophyly of the superfamily Rhamphichthyoidea is well accepted, despite the position of tribe Steatogenini (Steatogenys, Hypopygus and Stegostenopos) within this superfamily is unclear. The genus Steatogenys includes three species that, together with Hypopygus and Stegostenopos, form tribe Steatogenini. Cytogenetic information is currently only available for Hypopygus lepturus. Here, we describe the karyotypes of Steatogenys elegans from four localities and S. duidae from two localities. S. elegans was found to have 2n = 50, ZZ/ZW (12m-sm/38st-a), while S. duidae had 2n = 50 (50m-sm). In S. elegans, constitutive heterochromatin (CH) was observed in the centromeric regions of all chromosomes, in the interstitial region of 1q, and in two blocks of Wq. In S. duidae, CH was observed in the centromeric and pericentromeric regions of all chromosomes, and in the interstitial regions of 2q, 3q, 5q, and 7q. Nucleolar organizer regions (NORs) were identified in the distal regions of one chromosome pair in each species. The CMA₃ fluorochrome (specific to G-C rich regions) coincided with the NORs in both species, and with the HC of S. elegans except on chromosome pair 5 and the W. The DAPI fluorochrome (specific to A-T rich regions) coincided with the CH of both species, and was very intense for chromosome pair 5 and the W of S. elegans. Our observations suggest that the ZZ/ZW system observed in S. elegans likely evolved through CH addition followed by a paracentric inversion. The chromosomal data described herein are consistent with the phylogenetic hypothesis that tribe Steatogenini should be positioned within family Ramphychthyidae.     

Sex chromosome system ZZ/ZW in Apareiodon hasemani Eigenmann, 1916 (Characiformes,Parodontidae) and a derived chromosomal region

Parodontidae fish show few morphological characteristics for the identification of their representatives and chromosomal analyses have provided reliable features for determining the interrelationships in this family. In this study, the chromosomes of Apareiodon hasemani from the São Francisco River basin, Brazil, were analyzed and showed a karyotype with 2n = 54 meta/submetacentric chromosomes, and a ZZ/ZW sex chromosome system. The study revealed active NORs located on pair 11 and additional 18S rDNA sites on pairs 7 and 22. The 5S rDNA locus was found in pair 14. It showed a pericentric inversion regarding the ancestral condition. The satellite DNA pPh2004 was absent in the chromosomes of A. hasemani, a shared condition with most members of Apareiodon. The WAp probe was able to detect the amplification region of the W chromosome, corroborating the common origin of the system within Parodontidae. These chromosomal data corroborate an origin for the ZW system of Parodontidae and aid in the understanding of the differentiation of sex chromosome systems in Neotropical fishes.     

Chromosome banding study of European catfish,Silurus glanis (Pisces,Siluridae)

The karyotype of European catfish (Silurus glanis L.) was analyzed sequentially by means of silver staining and the chromomycin A₃ (CMA₃)/distamycin A (DA)/DAPI fluorescence technique and by C-banding, respectively. The nucleolus organizer regions (NORs) were localized on the submetacentric pair No. 14. Brilliant CMA₃ fluorescent heterochromatin blocks corresponded to the NORs visualized by silver staining. No DA/DAPI-bright positive fluorescent patterns were detected while C-banding led to the detection of specific banding patterns on several chromosome pairs.—Using these banding data, the karyotype of S. glanis was redescribed.     

Cytological evidence for population-specific sex chromosome heteromorphism in Palaearctic green toads (Amphibia,Anura)

A chromosome study was carried out on a number of European and Central Asiatic diploid green toad populations by means of standard and various other chromosome banding and staining methods (Ag-NOR-, Q-, CMA₃-, late replicating [LR] banding pattern, C- and sequential C-banding + CMA₃ + DAPI). This study revealed the remarkable karyological uniformity of specimens from all populations, with the only exception being specimens from a Moldavian population, where one chromosome pair was heteromorphic. Though similar in shape, size and with an identical heterochromatin distribution, the difference in the heteromorphic pair was due to a large inverted segment on its long arms. This heteromorphism was restricted to females, suggesting a female heterogametic sex chromosome system of ZZ/ZW type at a very early step of differentiation.