Chromosome studies of a fertile mammalian hybrid: the offspring of the cross bongo × sitatunga (Bovoidea)

The offspring of the cross bongo (Boocercus euryceros), 2n = 33 x sitatunga (Tragelaphus spekei), 2n = 30, has proved to be fertile. This fertility shows that the relationship between the karyotypes of the parental species is a simple one, despite the different diploid numbers and a different sex chromosome determinism, XX/XY in the sitatunga, XX/Y-to-autosome translocation in the bongo:meiotic processes and gametogenesis are not impaired in the hybrid.     

Chromosome studies in the mammalian subfamily Antilopinae

The karyology was studied in nine species of Antilopinae and evaluated with regard to cytotaxonomic relations within the subfamily. Karyotypes of three of these species were previously undescribed. Chromosomes were examined by conventional staining methods, G-, C-, and T-banding techniques, and by autoradiography. Evolutionary differentiation of karyotypes in this group is characterized by extensive Robertsonian fusions and a particular translocation between the X chromosome and an autosome. With comparison of Giemsa-banding patterns a taxonomy has been constructed which differs most markedly from the classical taxonomy in two aspects: the blackbuck, Antilope cervicapra, shows a strong karyotypic affinity to gazelles of the subgenus Nanger; Thomson's gazelle, Gazella thomsoni, lacks the numerous Robertsonian fusions and the X-autosome translocation common to other members of Gazella studied to date. Cases of intraspecific polymorphism of chromosome morphology and number are presented.     

Chromosome studies in plutonium workers

Chromosome analyses have been performed on peripheral blood lymphocytes from 54 men with estimates of plutonium body burdens in excess of 296 Bq. Both stable and unstable aberrations were scored using a banding technique and breakpoints noted. In discussing the significance of aberration frequencies the relative proportions of the different types of aberration and their distribution have been considered and account has been taken of external radiation exposure. It is suggested that significant depositions of plutonium do cause an increase in chromosome aberrations. The distribution of the breakpoints in the controls showed an excess in chromosomes 7 and 14. The formation and survival of radiation-induced breakpoints was randomly distributed amongst the chromosomes according to length. The distribution of the breakpoints within the chromosomes showed an excess in the centromeres and telomeres. Possible hot spots occurred in some of these regions and also in certain bands of the intermediate regions of the chromosomes.     

Chromosome studies in Alouatta belzebul

The chromosome constitution of Alouatta belzebul was studied with G-, C-, and silver staining. In ten specimens identified as Alouatta belzebul, the chromosome constitution of males (2n = 49) differed from that of females (2n = 50) owing to a Y-autosome translocation. In another single female specimen, probably Alouatta belzebul nigerrima, the diploid chromosome number was also 50, though its karyotype was drastically different from that of Alouatta belzebul belzebul. Chromosome studies, taken together with phenotypic and field observations, suggest that Alouatta belzebul belzebul is phenotypically variable in respect to pelage coloration. This attribute is therefore unreliable for the precise identification of Alouatta belzebul subspecies. Conversely, relatively minor phenotypic differences, allowing for the characterization of subspecies within a same species, coexist with unparalleled, drastic karyotypic divergence. These findings clearly question gross morphological attributes as discriminative characteristics of Alouatta belzebul subspecies.     

Chromosome studies in myelomatosis.

Cytogenetic studies of patients with multiple myeloma and plasma cell leukemia have shown that chromosome abnormalities occur in the bone marrow and/or the PHA-stimulated blood of at least half the patients. The abnormalities include numerical and structural aberrations and are highly variable. Hypodiploid modes occur fairly frequently. Addition of material to the long arm of the No. 14 chromosome (14q+ marker) occurs in about 17% of the small series of patients that have been studied with banding so far.     

Chromosome studies in bovine quintuplets

Chromosome analysis has been carried out on the four surviving calves of a bovine quintuplet set. Blood samples from all calves exhibited lymphocyte chimerism with greater percentages of male cells. Chromatid breaks and the presence of a hypodiploid cell carrying a metacentric marker were noted in varying proportions in all four calves. The possible relationship between chromosome abnormalities and immunological diversity between the calves have been discussed.     

Chromosome studies in a neonatal population

The results of chromosome studies on 6809 consecutive newborn infants are presented. One hundred and one (1.48%) were heterozygous for a marker chromosome, the significance of which is not at present clear. Twenty-two infants (0.32%) had a major chromosome abnormality. Only six of these infants (0.09%) had a clinically recognizable abnormal phenotype (Down''s syndrome). The occult chromosome abnormalities included five sex chromosome abnormalities (one 47,XYY; two 47,XXY; two 47,XXX) and 11 balanced translocations. Seven of these were t(DqDq) and four were reciprocal translocations. The results of the present survey are combined with four other similar neonatal surveys in which a total of 23,328 newborns have been screened. Of these, 117 (0.5%; range 0.65-0.32%) had major chromosome abnormalities. The majority of these (72.7%) would not have been detected at birth without chromosome studies, an important fact in the context of prenatal diagnosis of chromosome disease and the early ascertainment of high-risk families.     

Chromosome studies in some British bryophytes

Abstract

The chromosomes of one moss and thirty liverworts are described and discussed taxonomically. Those of Lepidozia pearsonii (n = 8 + 1m), Telaranea murphyae (n = 9), Leioeolea badensis (n = 8 + 1m), Pleetoeolea paroiea (n = 9), Nardia compressa (n = 8 + 1m), N. geoscyphus (n = 9), Lophoeolea bispinosa (n = 8 + 1m), L. semiteres (n = 8 + 1m), Saccogyna viticulosa (n = 8 + 1m), Scapania curta (n = 16 + 2m), S. compacta (n = 8 + 1m), Porella laevigata (n = 8 + 1m) and P. cordaeana (n = 8 + 1m) are believed not to have been reported previously and, despite references in the literature to the cytology of Riccia crystallina and Gymnocolea inflata, reasons are given for suggesting that the present counts of n = 7 + 1m and n = 8 + 1m, respectively, may also be the first. The remaining species have been recorded cytologically in other parts of the world but not previously for Great Britain, or not with the present karyotype.     

Chromosome studies in polycythemia vera.

Polycythemia vera (PV) represents an apparent monoclonal stem cell proliferation with a frequent transition to full neoplastic behavior. Up to 26% of untreated PV patients can be expected to have some chromosome abnormalities in the marrow at the time of diagnosis, and 10--15% have an abnormal cell line or clone. Both structural and numerical aberrations occur. Aneuploidy is the most common type of chromosome abnormality, however, with hyperdiploid clones occurring more frequently than hypodiploid clones. Chromosomes 1, 8, 9 and 20 are involved in a non-random pattern, and aberrations of all the F group, or at least the No. 20 chromosome seem to be associated to some extent with diseases involving erythroid hyperplasia. Leukemia develops in a certain percentage of patients regardless of the type of treatment they have received, but the relationship, if any, between the chromosome abnormalities and the development of leukemia is still uncertain. The abnormal clones that occur in PV appear to be quite stable and there is no indication at this time that they correlate with a prognosis of leukemic transformation.     

Chromosome studies in Orchidaceae from Argentina

The center of diversity of Argentinean orchids is in the northeast region of the country. Chromosome numbers and karyotype features of 43 species belonging to 28 genera are presented here. Five chromosome records are the first ones at the genus level; these taxa are Aspidogyne kuckzinskii (2n = 42), Eurystyles actinosophila (2n = 56), Skeptrostachys paraguayensis (2n = 46), Stigmatosema polyaden (2n = 40) and Zygostates alleniana (2n = 54). In addition, a chromosome number is presented for the first time for 15 species: Corymborkis flava (2n = 56), Cyclopogon callophyllus (2n = 28), C. oliganthus (2n = 64), Cyrtopodium hatschbachii (2n = 46), C. palmifrons (2n = 46), Galeandra beyrichii (2n = 54), Habenaria bractescens (2n = 44), Oncidium edwallii (2n = 42), O. fimbriatum (2n = 56), O. pubes (2n = 84), O. riograndense (2n = 56), Pelexia ekmanii (2n = 46), P. lindmanii (2n = 46) and Warrea warreana (2n = 48). For Oncidium longicornu (2n = 42), O. divaricatum (2n = 56) and Sarcoglottis fasciculata (2n = 46+1B?, 46+3B?), a new cytotype was found. Chromosome data support phylogenetic relationships proposed by previous cytological, morphologic and molecular analyses, and in all the cases cover some gaps in the South American literature on orchid chromosomes.     

Chromosome studies in a thymoma in vitro

Summary Chromosome studies were made in a tissue culture of a thymoma. The stemline was pseudodiploid with hypodiploid sidelines. A great variation of the chromosome numbers in the E group (losses) and G froup (gains) was observed.