Identification of crossbred buffalo genotypes and their chromosome segregation patterns

Chromosome analysis on different breed types of water buffaloes (Bubalus bubalis) was undertaken to identify their karyotypes and to determine the pattern of chromosome segregation in crossbred water buffaloes. Altogether, 75 purebred and 198 crossbred buffaloes including 118 from Malaysia and 80 from the Philippines, were analyzed in this study. The diploid chromosome number of the swamp buffalo from both countries was 48 and that of the river buffalo was 50, while all F1 hybrids exhibited 49 chromosomes. The F2 hybrids consisted of three different karyotype categories (2n = 48, 2n = 49, and 2n = 50), whereas the backcrosses included two different karyotype categories each, with 2n = 48 and 2n = 49 in the three quarters swamp types and 2n = 49 and 2n = 50 in the three quarters river types. Chi-square tests on pooled data from Malaysia and the Philippines indicated that the distribution of different karyotype categories of F2 animals did not deviate significantly from the 1:2:1 ratio expected if only balanced gametes with 24 and 25 chromosomes were produced by the F1 hybrids. In the three quarters swamp and three quarters river types, the respective karyotypic categories were in ratios approximating 1:1. The distribution of chromosome categories among the F2 hybrids and backcrosses suggests that only genetically balanced gametes of the F1 hybrids are capable of producing viable F2 and backcross generations.     

Karyotypic evolution of ribosomal sites in buffalo subspecies and their crossbreed

Domestic buffaloes are divided into two group based on cytogenetic characteristics and habitats: the “river buffaloes” with 2n = 50 and the “swamp buffaloes”, 2n = 48. Nevertheless, their hybrids are viable, fertile and identified by a 2n = 49. In order to have a better characterization of these different cytotypes of buffaloes, and considering that NOR-bearing chromosomes are involved in the rearrangements responsible for the karyotypic differences, we applied silver staining (Ag-NOR) and performed fluorescent in situ hybridization (FISH) experiments using 18S rDNA as probe. Metaphases were obtained through blood lymphocyte culture of 21 individuals, including river, swamp and hybrid cytotypes. Ag-NOR staining revealed active NORs on six chromosome pairs (3p, 4p, 6, 21, 23, 24) in the river buffaloes, whereas the swamp buffaloes presented only five NOR-bearing pairs (4p, 6, 20, 22, 23). The F1 cross-breed had 11 chromosomes with active NORs, indicating expression of both parental chromosomes. FISH analysis confirmed the numerical divergence identified with Ag-NOR. This result is explained by the loss of the NOR located on chromosome 4p in the river buffalo, which is involved in the tandem fusion with chromosome 9 in this subspecies. A comparison with the ancestral cattle karyotype suggests that the NOR found on the 3p of the river buffalo may have originated from a duplication of ribosomal genes, resulting in the formation of new NOR sites in this subspecies.     

Meiotic peculiarities in hybrid buffalo

The two varieties of the Water buffalo (Bubalis bubalis var. bubalis and Bubalis bubalis var. carabao) have 2n = 50 and 2n = 48 karyotypes, respectively. The F1 hybrids are thought to exhibit a karyotype of 2n = 49 and are known to be fertile. Meiosis was studied in 10 hybrid water buffalo bulls. Karyotypes of the bulls were prepared from leukocyte cultures and testicular biopsy samples in a routine manner and examined. Phenotypically the bulls showed characteristics of the hybrid buffalo. Five of the bulls carried 2n = 50 and 5 had 2n = 49. Multivalent chromosomes were found in diakinesis (metaphase I) cells of bulls with 2n = 49 karyotypes. Synapses were found in bulls of both karyotypes.     

Cytogenetic characterization of two species of Frieseomelitta Ihering, 1912 (Hymenoptera, Apidae, Meliponini)

The cytogenetic analysis of Frieseomelitta dispar and F. francoi revealed the chromosome numbers 2n = 30 and n = 15 and a karyotypic formula 2K = 4M+2M(t)+4A+20A(M). The number of chromosomes observed was consistent with those reported for other Frieseomelitta species. The occurrence of the M(t) chromosome and other features of the karyotype formulae suggest a close relationship between F. dispar, F. francoi and F. varia. Nevertheless, it was possible to differentiate the karyotypes of the species by DAPI/CMA(3) staining, which revealed GC-rich regions on two chromosome pairs of F. dispar: one acrocentric and one pseudoacrocentric. In F. francoi, the same kinds of regions were observed on a pair of metacentrics and on a pair of acrocentrics. Our analysis also confirmed the chromosome number conservation in Frieseomelitta and suggests that infrequent pericentric inversion could constitute a synapomorphy for the group including F. dispar, F. francoi, and F. varia.     

Karyotype of Saguinus labiatus labiatus (red-bellied marmosets)

The karyotype of Saguinus labiatus labiatus was determined by the Giemsa-banding technique on leukocytes cultured from 10 marmosets. The diploid chromosome number (2n = 46) was the same and the chromosome complement similar to other marmosets of genus Saguinus. Small karyotypic differences were found between S. l. labiatus and white-lipped marmosets (Saguinus fuscicollis) in the size of the X chromosome and in the banding pattern of one pair of metacentric chromosomes. A karyotypic variant was detected in 1 S. l. labiatus, characterized by a diploid chromosome number of 45 with balanced autosomal translocation involving two pairs of acrocentric chromosomes (T 16/19).     

Cytogenetic analysis of the tamaraw (Bubalus mindorensis): a comparison of R-banded karyotype and chromosomal distribution of centromeric satellite DNAs, telomeric sequence, and 18S-28S rRNA genes with domestic water buffaloes

The karyotype of the tamaraw (Bubalus mindorensis, 2n = 46) was investigated by RBG-banding technique and compared with those of the river and the swamp cytotypes of domestic water buffalo (B. bubalis). The tamaraw karyotype consisted of 6 submetacentric and 16 acrocentric autosome pairs (NAA = 56), and X and Y chromosomes. The RBG-banded karyotype of the three taxa had a high degree of homology, and the tamaraw karyotype could be explained by a Robertsonian translocation between chromosomes 7 and 15 and by a telomere-centromere tandem fusion between chromosomes 4p and 12 of the standardized river buffalo cytotype (2n = 50, NAA = 58). The buffalo satellite I and II DNAs were localized to the centromeric regions of all the tamaraw chromosomes. The biarmed chromosome 2 of the tamaraw resulting from the fusion between chromosomes 7 and 15 of the standard contained much larger amounts of the satellite I DNA than the other biarmed chromosomes, suggesting that this chromosome was formed by a relatively recent Robertsonian fusion. The (TTAGGG)n telomeric sequence was specifically localized to the telomeric region of all the buffalo chromosomes. The 18S + 28S rDNA was localized to the telomeric regions of the chromosomes 5p, 7, 19, 21, and 22 of the tamaraw and of their homologous chromosomes in the river and swamp buffalo cytotypes.     

Allozyme differentiation of various chromosomal forms of the spotted suslik (Spermophilus suslicus Guld, 1770, Rodentia)]

Eleven enzyme and four nonenzyme protein systems controlled by 25 loci were electrophoretically analyzed in the allopatric karyotypic forms (2n = 34 and 2n = 36) of the spotted souslik Spermophilus suslicus. Genetic variability and differentiation for the forms with different chromosome sets were estimated. Two discriminative loci (Alb and Tf) for the studied chromosome forms were found. The UPGMA dendrogram was constructed, which summarizes genetic (allozyme) relationships found for the forms of the spotted souslik with different chromosome sets. Subdividing the species into two karyotypic forms was shown to be followed by differentiating these forms at the allozyme level.     

从细胞学资料看金松属的系统位置

本文比较了金松(属)和杉科其他各属植物的核型,它的染色体数目(2n=20)和基数(x=10)较低,其核型最为对称。细胞学资料支持金松属从杉科分出另立金松科SciadopityaceaeHayata,它的系统位置则很可能比杉科来得原始。这也得到古植物学的支持。     

Chromosome banding in three species of <Emphasis Type="Italic">Hypsiboas</Emphasis> (Hylidae,Hylinae), with special reference to a new case of B-chromosome in anuran frogs and to the reduction of the diploid number of 2n = 24 to 2n = 22 in the genus

The chromosomes of hylids Hypsiboas albopunctatus, H. raniceps, and H. crepitans from Brazil were analyzed with standard and differential staining techniques. The former species presented 2n = 22 and 2n = 23 karyotypes, the odd diploid number is due to the presence of an extra element interpreted as B chromosome. Although morphologically very similar to the small-sized chromosomes of the A complement, the B was promptly recognized, even under standard staining, on the basis of some characteristics that are usually attributed to this particular class of chromosomes. The two other species have 2n = 24, which is the chromosome number usually found in the species of Hypsiboas karyotyped so far. This means that 2n = 22 is a deviant diploid number, resulted from a structural rearrangement, altering the chromosome number of 2n = 24 to 2n = 22. Based on new chromosome data, some possibilities were evaluated for the origin of B chromosome in Hypsiboas albopunctatus, as well as the karyotypic evolution in the genus, leading to the reduction in the diploid number of 2n = 24 to 2n = 22.     

Chromosome evolution in kangaroos (Marsupialia: Macropodidae): cross species chromosome painting between the tammar wallaby and rock wallaby spp. with the 2n = 22 ancestral macropodid karyotype.

Marsupial mammals show extraordinary karyotype stability, with 2n = 14 considered ancestral. However, macropodid marsupials (kangaroos and wallabies) exhibit a considerable variety of karyotypes, with a hypothesised ancestral karyotype of 2n = 22. Speciation and karyotypic diversity in rock wallabies (Petrogale) is exceptional. We used cross species chromosome painting to examine the chromosome evolution between the tammar wallaby (2n = 16) and three 2n = 22 rock wallaby species groups with the putative ancestral karyotype. Hybridization of chromosome paints prepared from flow sorted chromosomes of the tammar wallaby to Petrogale spp., showed that this ancestral karyotype is largely conserved among 2n = 22 rock wallaby species, and confirmed the identity of ancestral chromosomes which fused to produce the bi-armed chromosomes of the 2n = 16 tammar wallaby. These results illustrate the fission-fusion process of karyotype evolution characteristic of the kangaroo group.     

瓜尔豆和跌打豆的核型分析

本文报道了豆科瓜尔豆和旋花科跌打豆的染色体数目及核型．结果表明：瓜尔豆的染色体数目为２ｎ＝１６。核型公式Ｋ（２ｎ）＝１４ｍ＋２８ｍ,有７对具中部着丝点染色体和１对具近中部着丝点染色体。跌打豆的核型公式Ｋ（２ｎ）＝３０ｍ（２ＳＡＴ）,全部由具中部着丝点染色体组成。按Ｓｔｅｂｂｉｎｓ的分类标准,二者均属１Ａ类型。     

Characterization of yellow grouper Epinephelus awoara (Serranidae) karyotype by chromosome bandings and fluorescence in situ hybridization

The cytogenetics of yellow grouper Epinephelus awoara was studied using multiple cytogenetic markers [Giemsa staining, C-banding, Ag-NORs and fluorescence in situ hybridization (FISH)]. Giemsa staining results showed that the karyotypic formula of E. awoara was 2n = 48a, FN (fundamental number) = 48. Faint C-bandings were only detected at the centromeric regions of chromosome pair number 24, being almost indiscernible on the other chromosome pairs. After Ag-NOR staining, one pair of nucleolar organizer regions (NOR) was observed in the subcentromeric region of pair number 24. FISH results showed that 5S rDNA was located at a pair of medium-sized chromosomes, while 18S rDNA appeared at the same location in the subcentromeric region of pair number 24 where Ag-NORs were detected. The telomeric sequence (TTAGGG)(n) detected by FISH was located at both ends of each chromosome. The results suggested that E. awoara has retained general karyotypic structure stability during the evolutionary diversification process.     

角堇与大花三色堇染色体核型分析

以2份角堇与4份大花三色堇自交系为试验材料,采用染色体常规压片方法,观察和分析了它们的细胞染色体数目、相对长度、平均臂比等核型指标,以明确两种植物细胞学特点,为分类以及育种提供理论依据。结果表明:(1)2份角堇自交系染色体数目均为2n=2x=26,染色体基数为x=13,染色体核型公式分别为2n=2x=26=8m+12sm+6st、2n=2x=26=4m+16sm+6st,核型不对称系数为67.20%~70.10%,核型分类均属于3B。(2)4份大花三色堇自交系均为四倍体,其中2份(EYO-1-2-1-4、DSRFY-1-1-2)染色体数目为44,核型公式为2n=4x=44=4m+16sm+6st、2n=4x=44=16m+24sm+4st;2份(G10-1-3-1-4、XXL-YB-1-1-1-1)染色体数目为48,核型公式分别为2n=4x=48=8m+20sm+20st、2n=4x=48=4m+36sm+8st,核型不对称系数为66.74%~71.77%,核型分类属于2B、3B。     

广东四个墨兰品种的核型研究

研究了广东四个墨兰品种金嘴墨兰、银边墨兰、企剑黑墨和企剑白墨的染色体数目和核型。结果表明,企剑黑墨和企剑白墨的染色体数目为2n=40,为二倍体,核型公式分别为：2n=2x=40=30m＋10sm和2n=2x=40=2M＋36m＋2st;金嘴墨兰和银边睾兰的染色体数目为2n=41,为非整倍体。4个墨兰品种的染色体结构主要由中部着丝粒染色体组成,除银边墨兰为1B型外,其它均为2B型。     

Karyotype analysis in Brachiaria (Poaceae) species

This is the first karyotype characterization of Brachiaria species. Twelve accessions belonging to five species were analysed. The basic chromosome number was x = 9 and 7, the same reported for the tribe Paniceae. Variations in the chromosome number were observed in B. decumbens (2n = 18; 36) and B. humidicola (2n = 36; 42; 54). Chromosome numbers of 2n = 18 in B. ruziziensis and 2n = 36 in B. brizantha and B. jubata were recorded. Inter- and intraspecific karyotype differentiation of the accessions analysed was facilitated by variations in karyotypic symmetry. The karyotypes were generally considered symmetrical, with a tendency to asymmetry in the direction of the polyploids. It is suggested that addition, deletions and mainly polyploidy have been the most direct causes involved in the chromosome evolution of this genus.     

Chromosome Numbers and Karyotypes of Six Oxytropis Species (Fabaceae) from the Qinghai Tibetan Plateau,China

Chromosome numbers and karyotypes of 13 populations of six Oxytropis species (Fabaceae) from the Qinghai Tibetan Plateau, China, were presented. The chromosome numbers and karyotypes in O.ochrocephala, O.tatarica, O.kansuensis and O.humifusa (2n=16) were reported for the first time. B chromosomes were found from O.stracheyana (2n=48). The basic chromosome number of x=8 is confirmed for the genus. The available chromosomal data indicate that polyploidy may have played an important role in the evolution of the genus, with the incidence of polyploidy in the genus reaching 58%. However, our results indicated that among the populations here examined only one was a hexaploid with 2n=48. Such a chromosomal pattern indicates that the karyotypic repatterning at the diploid level seems to be the predominant feature of chromosomal evolution in the Oxytropis species from the Qinghai Tibetan Plateau, and that sympatric speciation via hybridization and polyploidization has played a minor role in the species diversification of the genus from this area.     

广西广义山蚂蝗属部分种类的核型及染色体数目报道

本文分析了广义山蚂蝗属６种１变种的核型,并报道了９种１亚种的染色体数目。假地豆Ｄｅｓｍｏｄｉｕｍｈｅｔｅｒｏｃａｒｐｏｎ（Ｌ．）ＤＣ．,伏毛假地豆Ｄ．ｈｅｔｅｒｏｃｏｒｐｏ。（Ｌ．）ＤＣ．ｖａｒ．ｓｔｒｉｇｏｓｕｍｖａｎＭｅｅｕｗｅｎ,单叶假地豆Ｄ．ｒｕｂｒｕｍ（Ｌｏｕｒ．）ＤＣ．．金钱草Ｄ．ｓｔｙｒａｃｉｆｏｌｉｕｍ（Ｏｓｂｅｃｋ．）Ｍｅｒｒ．及假木豆Ｄｅｎｄｒｏｌｏｂｉｕｍｔｒｉａｎｇｕｌａｒｅ（Ｒｅｔｚ．）Ｓｃｈｉｎｄｌ．的核型均为Ｋ（２ｎ）＝２２＝２２ｍ,属１Ａ类型．但它们的染色体相对长度变化范围有一定的差异,假木豆的较大,假地豆的较小。舞草Ｃｏｄｏｒｉｏｃａｌｙｘｍｏｔｏｒｉｕｓ（Ｈｏｕｔｔ．）Ｏｈａｓｈｉ和圆叶舞草Ｃ．ｇｙｒｏｉｄｅｓ（Ｒｏｘｂ．ｅｘＬｉｎｋ．）Ｈａｓｓｋ．的核型为Ｋ（２ｎ）＝２２＝２２ｍ,有的细胞可见随体染色体,属１Ｂ类型．根据核型资料比较．作者发现狭义的舞草属比狭义的山蚂螟属和假木豆属较为进化。本文还报道大叶山蚂蝗ＤｅｓｍｏｄｉｕｍｌａｘｉｆｌｏｒｕｍＤＣ,波叶山蚂蝗Ｄ．ｓｅｑｕａｘＷａｌｌ．绒毛山蚂蝗Ｄ．ｖｅｌｕｔｉｎｕｍ（Ｗｉｌｌｄ．）ＤＣ,异叶山绿豆Ｄ．ｈｅｔｅｒｏｐｈ?     

Chromosome number variation and evolution in Neotropical Leguminoseae (Mimosoideae) from northeastern Brazil

Most members of the subfamily Mimosoideae have pantropical distributions, variable habits, and a basic chromosome number x = 13. We examined karyotypic evolution of 27 species of this subfamily occurring principally in northeastern Brazil by examining chromosomes stained with Giemsa. All of the species had semi-reticulated interphase nuclei and early condensing segments in the proximal region of both chromosome arms. The basic number x = 13 was the most frequent, with 2n = 2x = 26 in 19 of the species, followed by 2n = 4x = 52 and 2n = 6x = 78. However, the three species of the genus Calliandra had the basic number x = 8, with 2n = 2x = 16, while Mimosa cordistipula had 2n = 4x = 32. The karyotypes were relatively symmetrical, although bimodality was accentuated in some species, some with one or two acrocentric pairs. As a whole, our data support earlier hypotheses that the Mimosoideae subfamily has a basic number of x = 13 and underwent karyotypic evolution by polyploidy. However, x = 13 seems to be a secondary basic number that originated from an ancestral stock with x(1) = 7, in which polyploidy followed by descending disploidy gave rise to the current lineages with x = 13. Another lineage, including current representatives of Calliandra with x = 8, may have arisen by ascending disploidy directly from an ancestral monoploid stock with x(1) = 7.     

广义烙铁头属三种烙铁头的核型及分类地位初步探讨

报道３种烙铁头蛇的核型。其中,烙铁头２ｎ＝３６＝１６Ｍ（１４Ｖ＋２ＳＶ／Ｖ）＋２０ｍ,ＺＷ型性决定,Ｚ为Ｖ型,Ｗ为ＳＩ／ＳＶ型,Ｚ明显大于Ｗ;菜花烙铁头２居群２ｎ＝３６＝１６Ｍ（１４Ｖ＋２ＳＩ）＋２０ｍ,ＺＷ型性决定,Ｚ为Ｖ型,Ｗ为ＳＩ型,Ｚ明显大于Ｗ;云南竹叶青２ｎ＝３６＝１６Ｍ（１２Ｖ／ＳＶ＋２ＳＶ／ＳＩ＋２ＳＩ）＋２ｍ,无异型性染本,对３种的核型及烙铁头属已知核型进行了比较分析,并对云南竹叶     

黑眶蟾蜍、黑斑蛙、中国雨蛙不同地理居群的染色体多样性

本文研究温州地区的黑眶蟾蜍、黑斑蛙、中国雨蛙的核型,分析了三个地理居群的黑星期五蟾蜍、四个地理居群的黑斑蛙、三个地理居群的中国雨蛙核型。结果表明不同地理居群的同种蛙有相同的染色体数和核型模式。黑星期五蟾蜍为2n＝22,NF＝44,核模式6＋5;黑斑蛙为2n=26,NF=52,核模式5＋8;中国雨蛙为2n＝24,NF＝48,核模式6＋6。但同一种蛙的不同地理居群之间在SM数目和顺序、次缢痕或随体的位置等有所不同。说明不同地理居群的同种蛙的染色体具有丰富的多样性。