中国多斑按蚊类群小记（双翅目：蚊科）

多斑按蚊Anopheles maculatus(Theobald)(s.l.)广布于我国北纬34°以南地区,过去都视作单一蚊种。根据近年的研究,它实际是包含若干亲缘种的种团。为此,我们检视了本单位收藏的标名为多斑按蚊的标本,发现有本种团的以下5种,多斑按蚊(s.s.)伪威氏按蚊pseudowillmori、塞沃按蚊sawadwonaporni、达罗毗按蚊dravidicus和威氏按蚊willmori,后两种为我国的新记录。 本文附有上述5种雌蚊的检索表。     

应用PCR—SSCP鉴别我国多斑按蚊复合体成员种（双翅目：蚊科）

测定并分析了我国多斑按蚊复合体5个成员种(多斑按蚊、威氏按蚊、伪威氏按蚊、达罗毗按蚊和塞沃按蚊)核糖体DNA 28S-D3序列,应用PCR-SSCP技术对该复合体成员种进行分子鉴别。结果显示：我国多斑按蚊复合体5个成员种的D3序列长度范围为388-394bp,GC含量为58．12％—59．79％,D3序列在种内保守,在种间存在差异,种间差异最大的是达罗毗按蚊与伪威氏按蚊为6．55％,最小的是达罗毗按蚊与多斑按蚊为2．58％,平均差异率为4．59％。用SSCP分析多斑按蚊复合体5个成员种的28S-D3扩增产物,结果显示电泳条带具种特异性,可用于鉴别各蚊种。     

云南省库态按蚊复合体的亲缘种型研究(双翅目,蚊科)(英文)

库态按蚊是1个由5种亲缘种型组成的按蚊复合体,这些种型分别被命名为A、B、C、D 和 E 型。在使用PCR 检测还没有条件的地区,鉴定库态按蚊亲缘种型的一个重要方法是作染色体组型分析。使用库态按蚊幼虫作染色体涂片,对云南地区的库态按蚊种型作了初步研究,并首次报道了该地区存在的亲缘种型成员,认为在云南省库态按蚊 A型和 B 型在同一个地区并存。同时,还展示了库态按蚊复合体的染色体组型、核型模式图及种型在中国毗邻国家的分布地图。     

赫坎按蚊与中华按蚊染色体的比较研究

细胞遗传学是蚊类、特别是按蚊复合种团分类和系统发育研究十分有用的方法之一(White,1984;Green等,1984)。采用细胞遗传学方法,结合生化、生活习性、生态和形态分类等技术,已经发现了许多按蚊近似物种的存在(Kitzmiller,1976;Coluzzi等,1979;Stegniy,1981),明确鉴别各按蚊近似种,对于制定有效的媒介控制措施有着重要意义。本文比较同属赫坎按蚊种团(Anopheles hyrcanusgroup)的两种近似种——赫坎按蚊(An.hyrcanus)和中华按蚊(An.sinensis)的唾腺多线染色体、有丝分裂染色体,确定它们在遗传学上的亲缘关系,为赫坎按蚊种团的分类和系统发育的研究提供资料。     

番鸭、连城鸭及其属间杂种的体细胞染色体比较

采用胚胎组织细胞和外周血白细胞短期培养法,分析了番鸭、连城鸭及其属间杂种F_1的体细胞染色体核型。番鸭的染色体2n=78,连城鸭2n=78±。它们的第1、2对常染色体分别为亚中或中间着丝点,其余均为近端着丝点;性染色体ZZ—ZW按大小顺序排列,Z为4,W为7—8。番鸭的Z和W染色体均属近端着丝点;连城鸭的Z染色体具明显短臂,属亚端着丝点,W染色体不具短臂,属近端着丝点,杂种F_1与亲本比较,染色体数目相同,但总臂数不同;第1、2对常染色体着丝点指数和臂比介于两亲本之间,其两个同源姐妹染色体的臂比分别偏向于父本和母本;性染色体着丝点位置具备两亲本的特点,可作为鉴定属间杂种真实性的依据。     

我国按蚊新纪录——雪足按蚊形态记述

雪足按蚊Anopheles nivipes(Theobald),1903隶属于环斑按蚊种团,曾被视为菲律宾按蚊的问种异名。Reid(1967,1968)和Klein等(1984)研究证明是两个独立种。作者从海南岛的成蚊和幼虫标本中发现有雪足按蚊,该蚊种为我国新记录。雪足按蚊成蚊和幼虫与近缘种非律宾按蚊和An.pallidus形态特征很近似,其主要鉴别特征如下表:表雪足按蚊与近缘种主要鉴别特征特征雪足按蚊菲律宾按蚊An.pallidus成蚊Ⅴ1分脉前黑斑较长,伸达或超过前缘脉的肩黑斑末端短,与前缘脉的等长或稍长常有变异Ⅴ3端部黑斑较长,为其附近缘缨长的2倍较长,约为附近缘缨长的2倍较…     

黑龙江省产两种草蜥染色体组型研究

采用常规骨髓细胞制片法,对黑龙江省产黑龙江草蜥和白条草蜥的染色体组型进行分析.结果表明,两种草蜥二倍体染色体的数目均是38,由18对常染色体和1对性染色体组成.常染色体中17对为端部着丝点染色体,1对为点状染色体;性染色体为ZW 型,从核型特征看来,二者都为蜥蜴目较原始的类型.     

国产毛茛科银莲花族十七种植物的细胞学研究

研究了国产毛茛科银莲花族Trib．Anemoneae 17种植物的染色体数目和核型。10种银莲花属 Anemone L．植物中,1种(西南银莲花A．davidii)为x=8的四倍体(2n=4x=32),5种(匍枝银莲花A． stolonifera、草玉梅 A．rivularis、卵叶银莲花A ．begoniifolia、水棉花A．hupehensis f. alba、大火草A．tomen- tosa)为x=8的二倍体(2n=2x=16),4种(鹅掌草A．flaccida、湿地银莲花A．rupestris、蓝匙叶银莲花 A．trullifolia var．colestina、拟条叶银莲花A．trullifolia var．holophylla、展毛银莲花A．demissa)为x=7的 二倍体(2n=2x=14)。罂粟莲花Anemoclema glaucifolium 为x=8的二倍体。6种铁线莲属Clematis L.植 物(滇川铁线莲C．kockiana、长花铁线莲C．rehderiana、毛茛铁线莲C．ranunculoides、扬子铁线莲C． puberula var．ganpiniana、短尾铁线莲C．brevicaudata、金毛铁线莲A．chrysocoma)均为x=8的二倍体。银 莲花属中x=7的种类的核型彼此十分相似,均由6对大型具中部着丝点的染色体和1对具端部着丝点 的染色体组成;x=8的二倍体种类的核型与罂粟莲花属和铁线莲属植物的核型十分相似,均由5对大型 具中部着丝点和3对具端部或近端部着丝点的染色体组成。     

桓仁林蛙和桓仁产东北林蛙的染色体组型

用骨髓细胞制片法对桓仁林蛙（Rana huanrenesis）和桓仁产东北林蛙（R．dybowskii）的染色体组型进行了报道,两种林蛙的染色体数均为2n=24,都可配成12对,按照相对长度可分为3组,A组包括第1～5对,为大型染色体（相对长度〉9．0）;B组是第6对,为中型染色体（相对长度在7．0～9．0之间）;C组包括第7～12对,这一组为小型染色体（相对长度〈7．0）。在两种林蛙的染色体组型中未发现有异型性染色体。桓仁林蛙的第1、3、4、5对为中部着丝点染色体,第9对为端部着丝点染色体,其余各对为亚中部着丝点染色体。东北林蛙的第1、2、3、4、5、6、8对为中部着丝点染色体,第9对为端部着丝点染色体,其余各对为业中部着丝点染色体。两种林蛙的第11对染色体长臂有明显的次缢痕。     

三种姬鼠的染色体比较研究

本文采用染色体分带技术（Ｇ－,Ｃ－带和银染色）,对中华姬鼠（Ａｐｏｄｅｍｕｓｄｒａｃｏ）、大林姬鼠（Ａ．ｐｅｎｉｎｓｕｌａｅ）和大耳姬鼠（Ａ．ｌａｔｒｏｎｕｍ）的核型进行了观察分析。结果表明：３种姬鼠的２ｎ均为４８。中华姬鼠的染色体均为端着丝点染色体。大林姬鼠的常规核型中,除１对中着丝点染色体（Ｎｏ．２３）外,其余均为端着丝点染色体。大耳姬鼠的核型中,有１３对端着丝点染色体,２对亚端着丝点染色体,１对亚中着丝点染色体和７对中着丝点染色体。中华姬鼠Ｃ－带核型中,所有染色体着丝点Ｃ－带都呈强阳性,异染色质非常丰富,Ｙ染色体整条深染。在大林姬鼠Ｃ－带核型中,Ｎｏｓ．７,１１,１５,２１,２２着丝点Ｃ－带弱化甚至近阴性,其余染色体着丝点异染色质Ｃ－带都呈现程度不同的阳性。且Ｎｏｓ．２,４,７有强弱不同的端位异染色质带。Ｘ染色体着丝点区有大块的异染色质斑带出现,Ｙ染色体整条深染。大耳姬鼠除Ｎｏｓ．３,４,１０,１２,１３染色体着丝点Ｃ－带很弱外,其余染色体着丝点Ｃ－带均呈阳性,并有８对（Ｎｏｓ．１６－２３）染色体出现异染色质短臂。从总体上看,大林姬鼠和大耳姬鼠的着丝点异染色质明显比中华姬鼠的少。中华姬鼠的Ａｇ－ＮＯＲ     

Intraspecific variation in sex heterochromatin of species B of the Anopheles dirus complex in Thailand

Cytological examination of F1 larval mitotic chromosomes from a total of 126 families of Anopheles dirus species B from southern Thailand populations has revealed a pronounced quantitative variation of constitutive heterochromatin in the two sex chromosomes. Five types of X chromosomes and four types of Y chromosomes have been identified in this study. Such gross variation in sex chromosomes is most likely due to a gradual acquisition of extra heterochromatin.     

An early stage of ZW/ZZ sex chromosome differentiation in Poecilia sphenops var. melanistica (Poeciliidae,Cyprinodontiformes)

The mitotic and meiotic chromosomes of the American cyprinodont fish Poecilia sphenops var. melanistica were analysed. All 46 chromosomes are telocentric. By specific staining of the constitutive heterochromatin with C-banding and various AT-specific fluorochromes, the homomorphic chromosome pair 1 could be identified as sex chromosomes of the ZW/ZZ type. All female animals exhibit a W chromosome with a large region of telomeric heterochromatin that is not present in the Z chromosome. These sex chromosomes cannot be distinguished by conventional staining; they represent the first demonstration of sex chromosomes in fishes in an early stage of morphological differentiation. The W heterochromatin and the telomeric heterochromatin in the two autosomes 18 show a very bright fluorescence when stained with AT-specific fluorochromes. This allows the direct identification of the chromosomal sex by examining the interphase nuclei: females exhibit three, males only two brightly fluorescent heterochromatic chromocenters in their nuclei. The significance of these ZW/ ZZ sex chromosomes and their specific DNA sequences, the dose compensation of the Z-linked genes, and the experimental possibilities using sex-reversed ZW males are discussed.     

Polymorphic patterns of heterochromatin distribution in guinea pig chromosomes

The chromosome complement and patterns of heterochromatin distribution (as demonstrated by the DNA d-r method) were studied from three different guinea pigs. Karyotype analyses showed that one of the females had a heteromorphic sex pair formed by a submetacentric X chromosome and a subterminal X chromosome originated by a shortening of the short arm (x-chromosome). The heterochromatin was mainly found in the pericentromeric areas of the autosomes and X chromosomes and in the short arm of pair 7. The Y chromosome exhibited a degree of heterochromatinization different from that of pericentromeric areas.—The analysis of the heterochromatin distribution in the X chromosomes showed that the smaller size of the heteromorphic x-chromosoine was probably due to a lack of heterochromatin in its short arm. Moreover, two out of the three animals studied had a heteromorphic pattern of heterochromatinization in the pair 21 characterized by heterochromatinization of the pericentromeric area in one chromosome and almost complete heterochromatinization of the other homologue.—It is suggested that most of the heterochromatin disclosed by the DNA d-r method is formed by repetitious DNA; and that the Y chromosome and perhaps some autosome regions in guinea pigs are formed by a type of heterochromatin with properties different from those of the constitutive and facultative heterochromatin (intermediate heterochromatin).Supported in part by NIH Grant 5-501-RR05672-02 and by NIH contract 70-2299.     

The contrasting role of heterochromatin in the differentiation of sex chromosomes: an overview from Neotropical fishes

During the evolutionary process of the sex chromosomes, a general principle that arises is that cessation or a partial restriction of recombination between the sex chromosome pair is necessary. Data from phylogenetically distinct organisms reveal that this phenomenon is frequently associated with the accumulation of heterochromatin in the sex chromosomes. Fish species emerge as excellent models to study this phenomenon because they have much younger sex chromosomes compared to higher vertebrates and many other organisms making it possible to follow their steps of differentiation. In several Neotropical fish species, the heterochromatinization, accompanied by amplification of tandem repeats, represents an important step in the morphological differentiation of simple sex chromosome systems, especially in the ZZ/ZW sex systems. In contrast, multiple sex chromosome systems have no additional increase of heterochromatin in the chromosomes. Thus, the initial stage of differentiation of the multiple sex chromosome systems seems to be associated with proper chromosomal rearrangements, whereas the simple sex chromosome systems have an accumulation of heterochromatin. In this review, attention has been drawn to this contrasting role of heterochromatin in the differentiation of simple and multiple sex chromosomes of Neotropical fishes, highlighting their surprising evolutionary dynamism.     

Evidence for male XO sex-chromosome system in Pentodon bidens punctatum (Coleoptera Scarabaeoidea: Scarabaeidae) with X-linked 18S-28S rDNA clusters

In scarab beetle species of the genus Pentodon, the lack of analysis of sex chromosomes in females along with the poor characterization of sex chromosomes in the males, prevented all previous investigations from conclusively stating sex determination system. In this study, somatic chromosomes from females and spermatogonial chromosomes from males of Pentodon bidens punctatum (Coleoptera: Scarabaeoidea: Scarabaeidae) from Sicily have been analyzed using non-differential Giemsa staining. Two modal numbers of chromosomes were obtained: 2n = 20 and 19 in females and males, respectively. This finding along with other karyological characteristics such as the occurrence of one unpaired, heterotypic chromosome at metaphase-I and two types of metaphase-II spreads in spermatocytes demonstrate that a XO male/XX female sex determining mechanism - quite unusual among Scarabaeoidea - operates in the species investigated here. Spermatocyte chromosomes have also been examined after a number of banding techniques and fluorescent in situ hybridization with ribosomal sequences as a probe (rDNA FISH). The results obtained showed that silver and CMA(3) staining were inadequate to localize the chromosome sites of nucleolus organizer regions (NORs) due to the over-all stainability of both constitutive heterochromatin and heterochromatin associated to the NORs. This suggests that heterochromatic DNA of P. b. punctatum is peculiar as compared with other types of heterochromatin studied so far in other invertebrate taxa. By rDNA FISH major ribosomal genes were mapped on the X chromosome.     

Arrangement of centromeres in mouse cells

Applying a staining procedure which reveals constitutive heterochromatin to cytological preparations of the mouse (Mus musculus), one detects heterochromatin pieces at the centromeric areas of all chromosomes except the Y. The Y chromosome is somewhat heteropyenotic in general but possesses no intensely stained centromeric heterochromatin. The arrangement of the centromeric heterochromatin in interphase cells is apparently specific for a given cell type. In meiotic prophase, centromeric heterochromatin may form clusters among bivalents. From the location of the centromeric heterochromatin of the X chromosome in the sex bivalent, it is concluded that the association between the X and Y (common end) in meiosis is limited to the distal portions of the sex elements.     

XX:XY sex chromosome system with X heterochromatinization: an early stage of sex chromosome differentiation in the Neotropic electric eel Eigenmannia virescens

An early stage of sex chromosome differentiation is reported to occur in the electric eel Eigenmannia virescens (Pisces, Sternopygidae) from populations of two tributaries of the Paraná river system (Brazil). Cytogenetic studies carried out in the two populations showed that the Mogi-Gua?u population is characterized by 2n = 38 chromosomes and undifferentiated sex chromosomes and the Tietê population presents 2n = 38 both for males and females and an XX:XY sex chromosome system. The X-chromosome is acrocentric, easily recognized by the presence of a conspicuous heterochromatin block in its distal portion; the Y-chromosome is probably one of the medium sized acrocentrics present in the male karyotype. BrdU induced R-bands of the two populations did not reveal any difference in the euchromatic regions of the chromosomes. AluI and HaeIII restriction enzyme digestion patterns and chromomycin A3 staining of the X-chromosome are presented. The possible role of heterochromatinization in the evolution of sex chromosomes in fish is discussed.     

Heterochromatin (C-bands) in somatic and male germ cells in three species ofMicrotinae

The C-banding patterns in the chromosomes ofMicrotus oeconomus, M. arvalis andM. ochrogaster demonstrate differences in the amount and distribution of heterochromatin. Autosomal centromeric heterochromatin appears as conspicuous blocks or as small dots, and in several chromosomes no heterochromatin was detected; interstitial heterochromatin was observed in one autosome pair ofM. ochrogaster. The sex chromosomes also demonstrate differences in the C-banding pattern. InM. oeconomus, the X chromosome exhibits a block of centromeric heterochromatin which is larger than that of the autosomes; this characteristic helps to recognize the X chromosomes in the karyotype. InM. arvalis no heterochromatin was appreciated in the sex chromosomes. The Y chromosomes ofM. ochrogaster andM. oeconomus are entirely heterochromatic. During male meiosis heterochromatin shows condensation, association and chiasma prevention; the sex chromosomes pair end to end in the three species. At pairing, the Y chromosome ofM. arvalis is despiralized, but it appears condensed again shortly before separation of the bivalent.     

Expression of heterochromatin by restriction endonuclease treatment and distamycin A/DAPI staining of Indian muntjac (Muntiacus muntjak) chromosomes

The constitutive heterochromatin of the Indian muntjac (Muntiacus muntjak) was examined following digestion with various restriction endonucleases (AluI, HaeIII, HinfI, and MboI), as well as by selective fluorescence staining with distamycin A plus 4'-6-diamidino-2-phenylindole. Distinct areas within the C-bands were found to have characteristic staining patterns which were more conspicuous in the sex chromosomes. Two dot-like structures resistant to AluI were found in the X and Y1 chromosomes in the same position as the nucleolus organizer regions.