云南8种树蛙的染色体组型比较研究

本文报道了云南８种树桂的染色体组型,并对目前所已知的树蛙种类的染色体组型进行了比较。锯腿小树蛙Ｐｈｉｌａｕｔｕｓｃａｖｉｒｏｓｔｒｉｓ（Ｇｕｅｎｔｈｅｒ）的２ｎ＝２６,５对大染色体和８对小染色体,９Ｍ＋４ＳＭ,ＮＦ＝５２,Ｎｏ．７长臂近着丝粒处和Ｎｏ．８短臂端部备有一个次缢痕;白颊小树蛙Ｐｈｉ．ｐａｌｐｅｂｒａｌｉｓＳｍｉｔｈ的２ｎ＝２６,５对人染色体和８对小染色体,８Ｍ＋５ＳＭ,ＮＦ＝５２,Ｎｏ．６短臂近着丝粒处有一个次缢痕。白颌大树蛙Ｒｈａ．ｍａｘｉｍｕｓＧｕｅｎｔｈｅｒ的２ｎ＝２６,５对大染色体和８对小染色体,９Ｍ＋４ＳＭ,ＮＦ＝５２;棕褶树蛙Ｒｈａ．ｆｅａｅＢｏｕｌｅｎｇｅｒ的２ｎ＝２６,５对大染色体和８对小染色体,９Ｍ＋４ＳＭ,ＮＦ＝５２;黑蹼树蛙Ｒｈａ．ｒｅｉｎｗａｒｄｔｉｉ（Ｂｏｉｅ）的２ｎ＝２６,５对大染色体和８对小染色体,９Ｍ＋４ＳＭ,ＮＦ＝５２,Ｍｏ．１短臂近着丝粒处有一个次缢痕;红蹼树蛙Ｒｈａ．ｒｈｏｄｏｐｕｓＬｉｕｅｔＨｕ的２ｎ＝２６,５对大染色体,１对中染色体和７对小染色体,９Ｍ＋４ＳＭ,ＮＦ＝５２;斑腿泛树蛙Ｐｏｌｙｐｅｄａｔｅｓｍｅｇａｃｅｐｈａｌｕｓ的２ｎ＝２６,５对大染色体     

银额果蝇自然群体分化过程中的细胞遗传学

对我国大陆银额果蝇的分布及其细胞遗传学进行了广泛的调查,发现了一种值得注意的新核型。该核型结构兼有早已认可的长、短两大类基本核型的特征,即核型中的两条同源４号染色体为１长１短型。含新核型的群体分布于我国大陆东南沿海一带的上海、福州、厦门和深圳。而且,这些自然群体内还出现“１长１短型”、“长型”和“短型”重叠并存的多态现象。跟踪研究表明,新核型具有不稳定的遗传性,能世代传递,它的频率随世代增长而降低,并不是突然消失。但是,在上海、福州群体内出现的“长型”至第十五代之后却全部消失。这种新核型大概是银额果蝇自然演化过程中的中间过渡核型,是该果蝇种群分化中的细胞遗传学变异的过渡表征     

蓟属两种植物的染色体研究

本文对蓟属（Ｃｉｒｓｉｕｍ）的两个形态相似的近缘种大刺儿菜和小刺儿菜进行了染色体研究,其中后者为首次报道。观察结果表明：两个种的染色体数目均为２ｎ＝２ｘ＝３４：它们的核型是：大刺儿菜．２ｎ＝２ｘ＝３４＝２０ｍ＋１２ｓｍ＋２ｓｔ：小刺儿菜．２ｎ＝２ｘ＝３４＝２２ｍ＋１０ｋｍ（２ＳＡＴ）＋２ｓｔ。通过核型比较,认为它们是两个独立的种．而且后者比前者进化。     

The karyotype and ultrastructural characteristics of spontaneous preimplantation mouse parthenotes

Karyotypic and light and electron microscopical analyses were made of spontaneous preimplantation mouse parthenotes from the LT/Sv inbred strain. It was found that the activated oocyte and developing embryos were diploid. We believe that diploidization is achieved by the oogonium undergoing a premeiotic mitosis without cytokinesis followed by two meiotic divisions, thus producing diploid parthenotes. The developmental events with respect to membrane specialization, such as junctional complexes, were similar to those observed in fertilized embryos. A unique feature of the developing parthenote was the failure of the mitochondria to change during the morula stage. The mitochondria retained a few irregularly oriented cristae rather than many transversely oriented ones observed in morulae developing from fertilized eggs. The significance of this observation is discussed.     

How stable are genomes of tropical woody plants? Heterozygosity in C-banded karyotypes ofPorcelia as compared withAnnona (Annonaceae) andDrimys (Winteraceae)

InPorcelia goyazensis (2n = 18) Giemsa C-banding patterns differ from those ofAnnona reticulata (2n = 14) and reveal structural heterozygosity. The amplitude of karyological variation in theAnnonaceae is greater than expected for a primitive woody family. In a comparison with other tropical angiosperm groups, the highly differentiated karyotype ofDrimys brasiliensis (2n = 86) is interpreted as being the end-point of numerous karyological changes.     

The chromosomes ofCunninghamia konishii,C. lanceolata,andTaiwania cryptomerioides (Taxodiaceae)

Karyotype analyses were conducted onCunninghamia konishii, Cunninghamia lanceolata, andTaiwania cryptomerioides, all members ofTaxodiaceae. The somatic chromosome number was found to be 2n = 2x = 22 in all species which concurrs with previous reports. The karyotypes are generally asymmetrical with the smaller chromosomes being more submedian than the larger ones. Chromosomes with unusual or specific structures, thought to be associated with the nucleolar organizing region, were found in each species.Cunninghamia species have a marker chromosome pair with an unusually long secondary constriction.Taiwania has an unusually long kinetochore region present in a submedian chromosome pair.     

Chromosomal variation and zoogeography inAteles

Karyotypes are reported from 21 spider monkeys distributed among five taxa of the genus Ateles.G- and C- banding techniques revealed variations between taxa. Two variants were discovered for chromosome 5, for chromosome 7, and for the Y chromosome. Four forms of chromosome 6 were seen. The variations are all probably pericentric inversions. One individual was heteromorphic at position 6. The data are compared with prebanding reports of Ateleschromosomes and reports of five animals studied with banding techniques. The variation in Ateleschromosomes is similar in degree to that found in other ceboid genera. The variants may be related to forest refugia formed during the Plio-Pleistocene. Karyotyping of many New World primates is required to ensure a homogeneous experimental group.     

Cytological identification of the genomes in pentaploidAllium neapolitanum using Giemsa C-banding

Two homoeologous sets of chromosomes in pentaploidAllium neapolitanum Cyr. (Liliaceae) are recognizable by their C-bands. The banding pattern is the same for one Californian and five Yugoslavian populations, suggesting a common chromosomal origin. Predominant meiotic association of identically banded homologues indicates a genomic formula of AA A_I BB, confirms an allopolyploid origin, and argues against genetically controlled pairing.     

Nutritional and karyotypic characterization of a haploid cell culture ofDaucus carota

Summary The purpose of this study was to optimize growth conditions for a strain of haploid carrot callus and to follow its karyotypic changes in a long span of time. The strain has been maintained in liquid suspension since September 1977. It has remained predominantly haploid in its karyotype since that time. The original explant was initiated and subsequently subcultured in Gamborg's B5 medium. The components of the B5 medium were omitted one at a time and sequentially added back to determine their minimum, optimum, and maximum nontoxic concentrations. These changes were made in the original formula: the addition of an organic buffering agent and an increase in the iron and other micronutrient concentrations. Using this slightly modified B5 medium, we assessed the effect on growth by single additions of amino acids, different carbon sources, growth regulators, and vitamins. No improvement in plating efficiency resulted from addition of any of these compounds. We conclude that there are factors limiting the plating efficiency of the haploid cells other than these tested, or that single additions will not make a discernible difference, or that growth promoting factors cannot be exogenously supplemented to cultured cells.     

反萼银莲花的核型分析

本文报道反萼银莲花的染色体数目及核型。其核型公式为K(2n)=6m+4sm(1SAT)+4st(1SAT)+2t,按照Stebbins的核型对称性分类标准应属于“2A”型。同时对本属的进化等问题也作了初步讨论。