蜘蛛的B染色体研究：I.武汉地区粽管巢蛛的B染色体（蜘蛛目：管巢蛛科）

首次发现武汉地区粽管巢蛛胚胎细胞中存在的Ｂ染色体,观察数目为１～２８条,Ｂ染色体数目从有丝分裂晚前到中期逐渐减少,在非整倍体细胞中,随着Ａ染色体的减少逐渐增多,Ｂ染色体形态稳定,大多数为等臂染色体,少数具有亚端着丝点和端着丝点,外观上明显小于Ａ染色体。     

金鱼(Carassius auratus)染色体组型的研究Ⅰ.鲫鱼和红龙睛金鱼染色体组型的比较

本研究利用血细胞培养的方法,分析比较了鲫鱼和红龙睛金鱼的染色体组型。研究结果表明,鲫鱼的染色体数目2n=100,由A组(中部着丝点)12对、B组(亚中着丝点)15对和C组(亚端和端部着丝点)23对染色体组成。A、B组为双臂染色体,C组为单臂染色体。染色体的总臂数为154。红龙睛金鱼二倍体的染色体数目也为100,同样分为A、B、C三组。红龙睛金鱼和鲫鱼二者不论在染色体数目上还是在染色体组型上都完全相同,很难找出它们之间明显的形态差异。鲫鱼和红龙睛金鱼雌雄个体之间,并未发现有异型的性染色体存在。     

蒙古长爪沙鼠染色体组型研究

目的　建立蒙古长爪沙鼠标准G带染色体的核型 ,提供可靠的细胞遗传学的背景数据。方法　雌、雄各 3只成熟长爪沙鼠 ,外周血淋巴细胞培养 ,制片、镜下观察分裂中期的淋巴细胞。随机计数 10 0个分裂细胞中的染色体数目 ,确立长爪沙鼠体细胞染色体数目。选择 10个典型细胞测量染色体基本数据 ,建立标准G带核型。结果　长爪沙鼠染色体数为二倍体 ,4 4条染色体 ,可划分A、B、C、D、E、F六组。中着丝点区域的 11对 ,主要分布A、C、E三组中 ;近中着丝点区域的染色体 5对 ,主要分布B组中 ;端着丝点区域的染色体 5对 ,主要分布D、F组中 ;x为第 6号中着丝点染色体 ,y为端着丝点的区域染色体大小在 14号与 15号染色体之间。结论　长爪沙鼠染色体为 2n =4 4 =2× 11m +2× 5sm +2× 5t+(x)m +(y)t     

大林姬鼠的核型与B染色体研究

采用骨髓染色体制片法 ,对分布于吉林长白山、山东泰山和陕西秦岭的大林姬鼠的染色体组型、C -带、G -带和减数分裂的染色体行为进行了观察分析。发现 3个地区标本的染色体数目存在着显著差异。东北标本的 2n =48～ 51 ,A组染色体为 48条 ,均由端着丝粒染色体组成 ,同时具有 1～ 3条B染色体 ,其形态为中着丝粒染色体 ;山东标本的 2n =53～ 62 ,A染色体同样为 48条端着丝粒染色体组成 ,具 5～ 1 4条B染色体 ,其中 1条为较大的中着丝粒染色体 ,其余为小的中着丝粒和点状染色体。秦岭标本 2n =48～ 49,A染色体为 48条端着丝粒染色体 ,具 1条形态很小的端着丝粒B染色体。3地标本的B染色体均存在个体间和个体内变异。长白山标本B染色体的细胞克隆数目为 1～ 2 ,泰山标本为 1～ 3。在 3地标本中 ,中着丝粒B染色体呈现C -带阴性 ,点状B染色体呈中度深染。通过对减数分裂的观察 ,多数B染色体是以单价体的形式存在。中国长白山种群的B染色体数目和形态与朝鲜种群相似。与欧洲种群存在着显著差异。泰山种群的B染色体数目和形态与朝鲜种群及欧洲种群均存在显著差异。泰山种群与秦岭标本同属华北亚种 ,但它们的B染色体形态和数目差别很大。     

温室希蛛染色体的观察(蜘蛛目:球蛛科)

报道了温室希蛛的染色体数目、形态结构和性染色体组成。从目前的结果可见,温室希蛛的染色体数目是:雄性体细胞染色体数为2n=22,雌性为2n=24。其性决定机制属于X_1X_2O型。所有染色体似乎均为端或亚端着丝粒染色体,这个结论被对其C-带标本的分析所证实。两个(对)X-染色体是最短的和次最短的,温室希蛛染色体C-带标本的分析没有观察到染色体间有明显的结构差异。在染色体G-带标本中,获得了稳定的带纹。     

温室希蛛染色体的观察（蜘蛛目：珠蛛科）

报道了温室希蛛的染色体数目,形态结构和性染色体组成,从目前的结果可见,温室希蛛的染色体数目是,雄性体细胞染色体数为２ｎ＝２２,雌性为２ｎ＝２４其性决定机制属于Ｘ１Ｘ２Ｏ型,所有染色体似乎均为端或亚端着丝粒染色体,这个结论被其对Ｃ－带标本的分析所证实,两个（对）Ｘ－染色体是最短的和次最短的,温室希蛛染色体Ｃ－带标本的分析没有观察到染色体间有明显的结构差异,在染色体Ｇ－带标本中,获得了稳定的带纹。     

家隅蛛的染色体（蜘蛛目：漏斗蛛科）

报告家隅蛛的染色体数目、形态结构和性染色体组成。实验结果表明:家隅蛛的染色体数目是:雄性体细胞为43,雌体为46。性别决定机制是X_1X_2X_3O型。3个(对)X染色体是全部染色体中最小的和次最小的。所有染色体几乎都是端或亚端着丝粒染色体,这一结论被对其C-显带标本的分析所证实。6~＃～14~＃染色体长臂末端有明显的结构异染色质。G-显带标本中,获得了清晰的带纹。     

太平洋鳕染色体核型及银染分析

以野生太平洋鳕为材料,采用植物血球凝集素（PHA）及秋水仙素体内注射法,取头肾细胞经低渗、固定后,常规空气干燥法制备染色体标本,并对其染色体核型进行了分析。结果表明,太平洋鳕的二倍体染色体数目为2n=46,核型公式为:2n=8m+6sm+20st+12t,NF=60,即有4对中部着丝点染色体、3对亚中部着丝点染色体、10对亚端部着丝点染色体和6对端位着丝点染色体,染色体臂数为NF=60;染色体经银染后,Ag-NORs在不同间期细胞中表现出多态性,数目为13,其中2个Ag-NORs的频率最高（82%）;在分裂相中,具有1个Ag-NORs的频率最高（87.1%）,且在第12对亚端部着丝点染色体的一条带有明显的次缢痕,为Ag-NORs所在区域,并未发现Ag-NORs联合现象及性别相关的异型染色体。       

迷宫漏斗蛛Agelena labyrinthica的染色体(蜘蛛目:漏斗蛛科)

报告迷宫漏斗蛛的染色体数目、形态结构和性染色体组成。结果表明,迷宫漏斗蛛体细胞染色体数目是:雄性2n=42,雌性2n=44,性别决定机制属X_1X_2O型。X染色体是全部染色体中最长的和最短的2个(对)。染色体似乎均为端或亚端着丝粒染色体,这由C-显带标本分析所证实,没有亚中着丝粒染色体的证据。C-带标本分析表明,常染色体中,各条染色体的C-带纹,其大小和染色深浅无明显差异,但X_2染色体上有明显宽的C-带纹。C-显带处理没有得到稳定的有重复性的带纹。     

迷宫漏斗蛛Aglena labyrinthica的染色体（蜘蛛目：漏斗蛛科）

报告迷宫漏斗蛛的染色体数目,形态结构和性染色体组成,结果表明,迷宫漏斗蛛体细胞染色体数目是：雄性２ｎ＝４２,雌性２ｎ＝４４,性别决定机制属Ｘ１Ｘ２Ｏ型,Ｘ染色体是全部染色体中最长的和最短的２个（对）,染色体似乎均为端或亚端着丝粒染色体,这由Ｃ－显带标本分析所证实,没有亚中着丝粒染色体的证据,Ｃ－带标本分析表明,常染色体中,各条染色全的Ｃ－带纹,其大小和染色深浅无明显差异,但Ｘ２染色体上有明显宽的Ｃ     

TRANSMISSION AND SIGNIFICANCE OF B CHROMOSOMES IN ANTHURIUM WAROCQUEANUM

Somatic and meiotic chromosomes of one plant of Anthurium warocqueanum J. Moore and its selfed offspring were analyzed. The parent showed 2n = 30 + 3B in both somatic cells and pollen mother cells. The B chromosomes divided normally in somatic cells, but meiotic associations of Bs varied. Three configurations of three B chromosomes were observed at metaphase I of parent meiosis: one trivalent, one bivalent and one univalent, or three univalents. The number of B chromosomes in offspring ranged from 0 to 6, indicating their transmission from both male and female gametes. Offspring with two B chromosomes appeared in greatest frequency. It was hypothesized that both male and female gametes of the 3 B parent frequently contained one B chromosome through the normal distribution of the bivalent Bs at meiosis and the elimination of the univalent B chromosome due to lagging. Examination of pollen mother cells of offspring also revealed irregular behavior of B chromosomes. With a high number of B chromosomes, normal A chromosome bivalent formation seemed to be reduced. No phenotypic effects of B chromosomes were observed.     

银额果蝇的B染色体研究 2.昆明群体的生活力和B染色体的关系

本文分析了钮额果蝇的生活力和B染色体的关系。结果表明,银额果蝇的B染色体在其生长和发育过程中具双重性调节作用。一方面,B染色体以单一的形式存在于单雌系核型中,即1B或2Bs,可刺激生长、发育,增强生活力。另一方面,在单雌系的细胞中存在多条B染色体,并形成核型多态性,这似乎对生长和发育又有一定的抑制作用而减弱其生活力。     

云南乌头属一新种及其B染色体的初步观察

本文描述了云南乌头属一个新种,即土官村乌头Aconitum tuguancunense Q．E．Yang,并对其B染色体进行了观察,发现其B染色体数目不但在同一居群的不同植株间有变化,即使在同一植株中也不稳定。     

中华大蟾蜍和花背蟾蜍间移核胚胎早期发育中染色体变化的研究

本研究以中华大蟾蜍和花背蟾蜍间正反核、质组合的移核胚胎为材料,对其三个不同发育阶段(囊胚晚期、原肠早期、原肠晚期)的移核胚胎染色体进行了组型分析。结果表明,无论以中华大蟾蜍囊胚细胞核作供体,花背蟾蜍去核未受精卵作受体的移核胚胎,还是相反组合的移核胚胎,在三个不同发育阶段,其染色体数目和形态均有变化,即:(1)表现出数目上有规律性的减少,一般减少2条、3条和4条;(2)出现异型染色体,如染色体断裂和双缢痕染色体;(3)表现出比较恒定的异常组型,即缺失第3染色体,多第4、5、6另染色体。在三个发育时期的分裂中期象中,具有2n=22者,中核组占40.3％-41.3％,花核组占52.3-53.1％。     

THE INTERSPECIFIC ORIGIN OF B CHROMOSOMES: EXPERIMENTAL EVIDENCE

Abstract.— A centric fragment was generated during the introgression of a chromosome region from Nasonia giraulti into N. vitripennis. This neo B chromosome carries the N. giraulti or 123⁺ gene for wild‐type eye color. Using this phenotypic effect, the transmission of this chromosome was analyzed. The supernumerary chromosome showed less than Mendelian segregation rate in meiosis and some mitotic instability manifested as mosaic phenotype for eye color. However, transmission rate and mitotic stability increased over successive generations. The transmission rate through male gametogenesis was nearly 100%. These results support the interspecific hybridization model for B chromosome origin and reveal that problems in chromosome stability can persist for several generations after “foreign chromosomes” are introduced into a different species. We suggest that hybrid zones should be investigated as possible sites for neo‐B chromosome generation.     

FINE STRUCTURE OF CHROMOSOMES

Electron micrographs of staminate hair cells of Tradescantia reflexa indicate that early prophase chromosomes are composed of a number of helically arranged chromonemata. Favorable preparations reveal as many as 64 identifiable subsidiary strands, assumedly arranged as intertwined pairs to form a hierarchy of pairs of pairs. The helices of the smallest discernible units have a diameter of about 125 A, with highly electron-scattering material disposed peripherally around a less dense "core." The wall of this peripheral ring has a thickness of about 40 A, and apparently represents another pair of coiled threads surrounding a 40 A central axis. The implications of the findings are discussed briefly.     

THE STRANDEDNESS OF MEIOTIC CHROMOSOMES FROM ONCOPELTUS

Meiotic chromosomes were isolated from male Oncopeltus fasciatus by dissecting the testes under insect Ringer's solution and spreading the living cells on the Langmuir trough. After being dried by the critical point method, preparations were examined under the electron microscope. Chromosomes at all stages of prophase prove to be multistranded. A significant increase in the number of parallel 250 A fibers in the chromosomes occurs between zygotene and diakinesis. Parallel folding, rather than true multistrandedness, is interpreted as the mechanism responsible for this observed increase in multistrandedness. It has not been possible to determine whether the multistrandedness observed at leptotene represents true multistrandedness or is the result of parallel folding. Apparent multistrandedness is lost at metaphase when the 250 A fibers of the chromosomes become coiled more tightly. In preparations isolated by these methods, no structures other than the 250 A chromosome fibers are visible in the chromomeres, which appear as regionally coiled or folded areas of the fibers along the arm of the chromosome.     

GEOGRAPHICAL DISTRIBUTION OF B CHROMOSOMES OF XANTHISMA TEXANUM (COMPOSITAE: ASTEREAE). II. LOCAL VARIATION WITHIN AND BETWEEN POPULATIONS AND FREQUENCY VARIATION THROUGH TIME

Variation in the frequency of individuals of Xanthisma texanum with B chromosomes among populations at the local level and variation in the frequency and distribution through time of individuals with B chromosomes within populations was investigated in a small area of southwestern Oklahoma and adjacent Texas between 1974 and 1987. The chromosome numbers of 1,224 individuals were determined from meiotic material; 15.8% of these had B chromosomes, less than 1% had three or four B chromosomes; none had more than four B chromosomes. The frequency of plants with B chromosomes among all sites sampled ranged from 0 to 33% and from 0 to 25% in sites separated by only a hundred meters; large differences in sample size occurred. Even at the subsite level large differences in frequencies in plants with B chromosomes were found. Within single sites, B chromosome frequency was not constant through time: the pattern of change differed among subsites within populations. In some cases the frequency went to zero. No correlations between environmental parameters and B chromosome frequency were documented.