摘要:

Lymphocytes obtained from cardiac blood and thoracic duct lymph of the opossum (Didelphis virginiana) were incubated in short-term culture with phytohemagglutinin. Relatively pure inocula of lymphocytes were prepared through elimination of erythrocytes and granulocytes. A critical condition for successful culture growth was found to be the use of heat-inactivated rat serum in place of autologous or isologous sera. Because of rapidly occurring bursts of DNA synthesis, cellular transformation and mitotic activity, cultures were harvested at one half the incubation time common to human blood cultures and those of other laboratory animals. Opossum lymphocytes provide excellent material for cytogenetic investigations because of this short incubation requirement and because their chromosomes are large and few in number. Particularly significant is the ease with which the sex chromosomes may be identified.

ISSN:1424-8581    

DOI:10.1159/000129966

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

The Old World camels of the genus Camelus have diverged from the New World camels of the genera Lama and Vicugna over a period of more than a million years of their evolution. The two groups of modern camelids have evolved numerous different adaptations, but they retain a number of phenotypic similarities. Chromosome preparations made in this laboratory from cultured cells of various tissues demonstrate notable similarity of the karyotypes of two Old World camelids and one of the New World forms. Comparison with the work done by Benirschke’s group indicates that current methods of preparation present a remarkable uniformity of the karyotypes among all of the camelids. One female guanaco possessed a negatively heteropycnotic X in all cells examine

ISSN:1424-8581    

DOI:10.1159/000129967

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

Cell cultures derived from the heart (GH-1) and lung (GL-1) of an adult male Tokay gekko (Gekko gecko) have been serially propogated for more than two years. Cytogenetic examination of primary cultures as well as various subcultures from different passage levels of both lines was undertaken. The diploid karyotype possesses 38 chromosomes with no evident heteromorphic pair in either sex nor presence of microchromosomes. In the cultured cells, a bimodal distribution of chromosome numbers (38 and 40) was evident in both the GH-1 and GL-1 lines. The same subtelocentric chromosome was affected in both lines. In the GH-1 line, this element appeared tetrasomic, but one member of the group appeared to have undergone a pericentric inversion. The GL-1 line also showed tetrasomy for this chromosome. Attempts to repeat this karyotypic alteration by thawing cells frozen at low passage levels were unsuccessful, although cells from these cultures possessing 39 chromosomes were trisomic for the subtelocentric chromosome.

ISSN:1424-8581    

DOI:10.1159/000129968

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

Karyological examination of 26 species of bats from the family Phyllostomidae revealed two Y chromosomes (XY1Y2) in six species involving three genera. All females are of the XX constitution. Meiotic studies demonstrate the origin of the additional Y in Carollia to be the homolog of an autosome translocated to the X element. The origin of an additional Y in Artibeus is best explained as a separate event. In one species of Artibeus (A. turpis) a centric fusion of the two Y elements is emphatically suggested.

ISSN:1424-8581    

DOI:10.1159/000129969

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

The aim of this study is to determine why, in contrast to expectations based on the Lyon hypothesis, a variable number of nuclei of cells from mammalian females are sex chromatin negative. The frequency of sex chromatin positive nuclei was determined in cell cultures of varying cell densities. The cells were derived from seven chromosomally normal human female embryos, one newborn female with an extra E group chromosome and two normal male embryos. In all cultures of females the frequency of sex chromatin positive nuclei increased linearly from about 35% to 60% at cell densities of less than one cell per 0.01 mm2 of culture surface to 90% to 100% at densities of 20 to 125 cells per 0.01 mm2. This frequency-to-density relationship was independent of the mitotic rate and the rate at which cell density increased. When large variations in cell density were produced intentionally on the same glass coverslip, sex chromatin frequency was related to the density of cells in any one area of a coverslip and seemed to be largely independent of the cell density in other parts of the coverslip. The frequency of sex-chromatin-like bodies of male cultures remained very low at all cell densities. These and other preliminary observations described suggest that, in the nucleus of the female, sex chromatin formation resulting from the condensation of an X chromosome at interphase is not directly related to the mitotic cycle but may be related to the metabolic state of the cell.

ISSN:1424-8581    

DOI:10.1159/000129970

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

Sex chromatin counts for more than 50 individuals with three or more X chromosomes in their complement were analyzed. The observed distribution of cells with 0, 1, 2,...n sex chromatin bodies in polysomic-X individuals was compared with the binomial distribution expected on the assumption of a constant probability that an X chromosome will form a visible sex chromatin body. The sex chromatin count distribution deviated significantly from a binomial distribution in approximately half of the cases, usually in the direction of an excess of cells in the extreme classes (with 0 or n sex chromatin bodies, where n is usually 2 or 3). This indicates that the probability that an inactive X chromosome will form a visible sex chromatin body is not constant but varies, perhaps in relation to the cell cycle. The existence of cells with less than the maximum number of sex chromatin bodies therefore cannot be due solely to technical factors acting at random on all inactive X chromosomes. The sex chromatin count distribution appears to be different in newborn and postmenopausal XXX females, especially the latter, where nearly half had a deficiency of cells in the extreme classes. Most of this subgroup had sexual abnormalities, and many were schizophrenic. The types of deviation from the binomial distribution which would be produced by between-cell and within-cell variation in the probability of sex chromatin body formation, by mosaicism and by activation of an X chromosome are outlined. Various biological interpretations of the observed deviations are discussed, including the role of the cell cycle, hormones and other environmental factors.

ISSN:1424-8581    

DOI:10.1159/000129971

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

Karyotypes and a composite idiogram are presented for the parent species. Viable hybrids obtained by fertilizing eggs of Bufo americanus with Rana pipiens sperm were obtained. Chromosomal analysis of these hybrids demonstrated that they had a diploid number of 24 chromosomes, intermediate between 22 for B. americanus and 26 for R. pipiens. Fourteen of the chromosomes of the hybrids could be identified on the basis of structural characteristics or measurements as to their parental origin. The remaining ten chromosomes could not be identified with certainty because of similarities of these in the parents.

ISSN:1424-8581    

DOI:10.1159/000129972

出版商:S. Karger AG    

年代:1968

数据来源: Karger

ISSN:1424-8581    

DOI:10.1159/000129973

出版商:S. Karger AG    

年代:1968

数据来源: Karger