bluuebunny/crossref_metadata_2025 huggingface dataset:
A Mouse Translocation Suppressing Sex-Linked Variegation
Authors: Lyon Mary F. , Searle A.G. , Ford C.E. , Ohno S.
Published: April 2008

Female mice heterozygous for the sex-linked gene tabby (To) normally show a striped or variegated coat pattern resulting from random inactivation of one or other X-chromosome. In a stock descended from an irradiated female this variegation did not occur and heterozygotes for tabby looked wild-type. This led to the hypothesis that the wild-type allele of Ta had been translocated to an autosome and so was remaining active in all cells; the presence of a reciprocal X-autosome translocation was then demonstrated cytologically. A similar suppression of variegation was found for two other sex-linked genes, bent-tail (Bn) and blotchy {Bld), and also for both tabby and blotchy in crossover animals which had the mutant alleles on their translocated X-chromosomes. In these animals the mutant allele was fully expressed and the wild-type allele not at all. This showed that, in addition to the translocated X being active, the normal X was inactive in all cells, and demonstrated that the variegated effect in normal heterozygous females depended on the randomness of X-inactivation. Linkage tests suggested that the order of loci in the X chromosome was Bn-bteak-Ta-Blo, but this was not firmly established. The autosome involved in the translocation has not yet been identified.
Role of Fetal Follicular Cells in Meiosis of Mammalian Oöcytes
Authors: Ohno S. , Smith J.B.
Published: April 2008

Cytological and histological studies on ovaries from cattle fetuses of various stages indicate that the factor leading oöcytes in first meiotic prophase to enter dictyotene is contact with follicular cells. Early in embryonic development, each ovigerous cord in the upper layer of the ovarian cortex appears to contain a disproportionately greater number of germ cells than potential follicular cells. Many of these oöcytes enter meiosis and proceed beyond diplotene to diakinesis, only to degenerate. As the fetal ovary develops, the correct ratio of germ cells to potential follicular cells is gradually established, from deep in the cortex upward. An individual oöcyte in first meiotic prophase is now surrounded by a single dense layer of follicular cells; only these oöcytes are capable of entering dictyotene and forming primordial follicles. Precocious oöcyte maturation appears to be forestalled by the intimate contact of the follicular cells, which seems to force the oöcyte nucleus to maintain the non-homologous association of its bivalents.
Successive Non-Disjunction at First and Second Meiotic Division of Spermatogenesis: Evidence of Chromosomes and Xg
Authors: de la Chapelle A. , Hortling H. , Sanger Ruth , Race R.R.
Published: April 2008

An Xg(a+) male with XXYY sex chromosomes was the son of an Xg(a+) father and an Xg(a—) mother with normal chromosomes. This seems to be the first example in which there is good evidence of non-disjunction at the first and second meiotic division of paternal spermatogenesis, giving rise to an XYY sperm which fertilized a normal ovum. Other explanations are discussed.
Somatic Chromosomes of the Indian Five Striped Squirrel Funambulus Pennanti Wroughton
Authors: Rao Venkatasubba , Sharda
Published: April 2008

The diploid chromosome number of the Indian five striped squirrel {Funambulus pennanti, Wroughton) is 54 with a preponderance of acrocentric chromosomes. On the basis of chromosome number and morphology the interrelationships of the different species of squirrel are discussed.
Chromosomal Autoradiography in the Cri du Chat Syndrome
Authors: German J. , Lejeune J. , Macintyre M.N. , De Grouchy J.
Published: April 2008

The pattern of DNA synthesis in the chromosomes of Group 4–5 has been analysed in cells from individuals with the cri du chat syndrome. The abnormal chromosome, a No. 5, is one of the pair characterized by relatively early completion of synthesis in the long arms. The two remaining members of this group, characterized by extensive late replication throughout their lengths, therefore may now be recognized as the Nos. 4.
Anatomical and Cytological Sex of a Saanen Goat
Authors: Basrur Parvathi K. , Coubrough R.I.
Published: April 2008

A Saanen goat registered as female was found to have a pair of abdominal testes, a well developed uterus and a prominent clitoris. The chromosome features of peripheral leukocytes and the nuclear sex chromatin pattern of lymphocytes and testicular cells conformed to those of a cytological female. The testicular tissue showed all stages of meiosis and fully formed sperm indicating normal spermatogenesis. The anatomical and cytological features of this goat are compared with those of human intersexes and hermaphrodites previously reported and the disparity between the gonadal and cytological sex in this goat is discussed.
Endoreduplication in Human Fibroblast Cultures
Authors: Schwarzacher H.G. , Schnedl W.
Published: April 2008

Chromosome preparations using hypotonic pretreatment and air drying have been examined from 5 different human euploid fibroblast cultures. Between 0.1 and 4.1% of mitoses are found to be tetraploid with the chromosomes arranged as diplochromosomes. 0.5–5.8% of the mitoses are tetraploid with randomly positioned chromosomes. Differences in the frequency of polyploid mitoses between two cultures set up from one biopsy may be greater than between cultures from different individuals. The structure of the chromosomes forming diplochromosomes is identical to that of the chromosomes in diploid mitosis. In prophase the two chromosomes of a diplochromosome lie close together but are not linked at the centromere. In late prophase and metaphase the two chromosomes of a diplochromosome usually remain together but sometimes lie apart. In late anaphase and telophase no pairing of daughter chromosomes can be found. In prophases of cells from females, one of the chromosome pairs, presumably an X-diplochromosome, may show heteropyknosis. It is assumed that diplochromosomes originate mainly through endoreduplication. The mitosis following a mitosis with diplochromosomes will presumably show the chromosomes in random position. Autoradiographic studies using 3H-thymidine show that diplochromosomes originate from two successive chromosome duplications. The cycle leading to diplochromosomes has approximately the same duration as two cycles of a diploid cell. The late labelling pattern, especially the late labelling X-chromosome in cells of females, is found in diplochromosomes in the same order as in chromosomes of diploid cells. The grain pattern of diplochromosomes labelled during first chromosome duplication indicates a semi-conservative mode of segregation.
The Induction of Chromatid Lesions by Cytosine Arabinoside in Post-DNA-Synthetic Human Leukocytes
Authors: Brewen J.G.
Published: April 2008

When cultures of human leukocytes are treated with tritiated thymidine and cytosine arabinoside, it is observed that all of the aberrations induced by the cytosine arabinoside are induced in unlabeled (G2) cells. Furthermore, very few labeled cells reach metaphase, indicating that the cells in S at the time of treatment are either slowed or stopped in their progression to metaphase. The time from the end of S to metaphase is estimated to be 2 ½ to 3 ½ h in normal cultures.
Meiotic and Mitotic Studies of a Familial Reciprocal Translocation Between Two Autosomes of Group 6–12
Authors: Lindsten J. , Fraccaro M. , Klinger H.P. , Zetterqvist P.
Published: April 2008

A reciprocal translocation between two autosomes of the 6–12 group was found in a balanced state in four phenotypically normal members of a family. Ascertainment was through a severely affected girl with an unbalanced state of the translocation. Meiotic studies in one carrier of the balanced state confirmed the nature of the reciprocal translocation and made it possible to exclude the involvement of an X chromosome.
Differential Contraction of Large and Small Chromosomes in Cultured Leucocytes of Man
Authors: Fitzgerald P.H.
Published: April 2008

The summed lengths of chromosomes Nos. 1 and 2 (x) were compared with the summed lengths of the small acrocentric chromosomes, Nos. 21, 22 and in males the Y chromosome (z), in 10 cells from each of 10 males and 5 females. Both chromosome groups varied in length together, but the changes were proportionally less in the small acrocentric chromosomes than in the large chromosomes. This was the case in both sexes. The relative changes in chromosome length were expressed by the regression coefficients z = 0.1461 x + 5.55 in males and z = 0.1077x + 4.32 in females. It was considered that this differential contraction might be peculiar to the stage of chromosome contraction examined and that compensatory contraction occurred at other stages, or, on the other hand, that the greater degree of contraction of the large chromosomes involved an additional order of chromosome coiling.
Sex Chromatin Body Size and its Relation to X Chromosome Structure
Authors: Taft P.D. , Dalal K.P. , McArthur J.W. , Worcester J.
Published: April 2008

Sex-chromatin body size was estimated in seven normal women and in four patients with known X chromosome abnormalities by multiplying the length and breadth of 50 bodies in a buccal smear, as measured by a micrometer ocular. The area of the sex-chromatin body proved to be directly proportional to the size of the X chromosome as noted in the karyotype; in cases with an iso-X chromosome the sex-chromatin bodies were significantly larger than in the pooled normal controls; in cases of presumptive deletions they were significantly smaller. Measurements obtained by this simple technique agree closely with those obtained planimetrically. They are more trustworthy than visual impressions by observers lacking wide experience in cytologic interpretation and, in borderline cases, may have value in pointing to a need for determination of the karyotype.
DNA Content and Area of Sex Chromatin in Subjects with Structural and Numerical Aberrations of the X Chromosome
Authors: Klinger H.P. , Lindsten J. , Fraccaro M. , Barrai I. , Dolinar Z.J.
Published: April 2008

Sex chromatin deoxyribonucleic acid (SC/DNA) content (determined by Feulgen-photometry) was higher in cultured cell nuclei derived from five women with presumptive iso-chromosomes for the long arm of the X than from five normal women. The mean SC/DNA values from subjects with deleted long arm or short arm iso-chromosome X; deletion of the short arm of X and from lymph node cultures of a subject with a ring X were significantly lower than the control values. SC/DNA from subjects with XY/XXY, XXXY and XXXXY sex chromosome constitutions did not differ from control values. In oral mucosa nuclei the mean SC/DNA and sex chromatin area from the subjects with structurally abnormal X’s also showed a correlation between X chromosome size and SC/DNA or SC/area but in this technically less suitable tissue variability was greater and the differences not statistically significant. These findings indicate that: 1. Only one X chromosome forms sex chromatin. 2. When a structural abnormality of the X is present it is always the abnormal one which becomes positively heteropycnotic. 3. It is probably all, or at least the major portion of the X which forms sex chromatin. 4. The multiple sex chromatin bodies formed in cells with supernumerary X’s contain average amounts of DNA. 5. Visual impression of sex chromatin “size” (staining intensity and area integrated) can be confirmed objectively.
Chromosome Changes in Rat Embryos Following X-Irradiation
Authors: Soukup Shirley W. , Takacs Eva , Warkany J.
Published: April 2008

A study was made of chromosome changes in rat embryos after exposure to teratogenic doses of x-rays. Two methods were used for chromosome analysis: a direct method permitting analysis of chromosomes soon after removal of the embryos from the uterus, and a method in which the embryonic cells were first grown in tissue culture for several days after removal, before they were processed. The direct method proved superior to the tissue culture method for demonstrating early chromosome changes. A half day after irradiation a high incidence of chromosomal aberrations was found which dropped rapidly and returned to almost normal values after several days.
Cytogenetics of Down’s Syndrome (Mongolism) II. The Frequency of Interchange Trisomy in Patients Born at a Maternal Age of less than 30 Years
Authors: Giannelli F. , Hamerton J.L. , Carter C.O.
Published: April 2008

A survey of 96 consecutive families whose Down’s syndrome index patients were born at a maternal age of less than 30 years, is reported. Seven cases of interchange trisomic Down’s syndrome were found, four of the D/G21 and three of the G21/G types; in two of the D/G21 and one of the G21/G cases, the interchange was inherited from a parent. In the remaining 89 families, the index patients proved to be examples of primary G21 trisomic Down’s syndrome. The mother of one of these carried a D/D interchange. The importance of chromosome studies for the genetic counselling of parents of Down’s syndrome children, is summarised.
Multiple Clones with Increase in Number of Chromosomes in the G Group in a Case of Myelomonocytic Leukemia
Authors: Atkins L. , Goulian M.
Published: April 2008

A 71-year-old man with myelomonocytic leukemia was found to have multiple cell lines in the peripheral blood and bone marrow. One line was apparently normal and the other lines showed increases to as many as 8 chromosomes in the G group. Many of these supernumerary chromosomes appeared to be Y chromosomes. Additional findings included scattered gains and losses of chromosomes in Groups C, D, E and F.
Abnormal Sex Chromosomes in a Rare Case of Intersexuality Lacking Internal Genitalia
Authors: Köbberling J. , Hinrichsen K. , Ristedt T.
Published: April 2008

In a female patient, aged 24, neither gonads nor internal genitalia could be found, only a penis-like formation of 3–4 cm in her pubic region. A peripheral blood culture revealed 46 chromosomes with a normal X but deleted Y. Although no rudimentary gonads could be found at laparotomy, one can conclude by comparison with other forms of intersexuality that the defective Y must have induced an incomplete testisanlage. This primitive testis was able to suppress formation of female genitalia but unable to complete masculinisation. As a result an intersexual state developed with rudimentary Wolffchen and Müllerian ducts.
A Method for Culturing Leucocytes of Rats and Rabbits
Authors: Williams T.W. , Ray M.
Published: April 2008

Rats and rabbits were immunized with human AB serum or albumen. Leucocyte cultures were set up three to four weeks later. Numerous mitotic figures were obtained in cultures to which both phytohemagglutinin and human serum were added. No mitotic divisions were observed in non-immunized controls.
The Chromosome Complement of the Howler Monkey (Alouatta caraya, HUMBOLDT 1812)
Authors: Egozcue J. , De Egozcue Vilarasau
Published: April 2008

The chromosome complement of the howler monkey (Alouatta caraya) has been studied in blood cultures cultivated in vitro for four days. The chromosome number is 52. The Y chromosome is acrocentric and ranks 19 in decreasing order of size. The X chromosome is submetacentric and ranks seventh in the same order. The autosomes, 4–14 µm long in metaphase, with arm ratios from 1.2 to 8.8, are arranged and numbered in order of decreasing size. Chromosomes 12, 18, 20, 22 and 24 are satellited, pairs 18 and 20 being the first metacentric satellited chromosomes to be described as a regular feature in higher animals.Chromosomes 21 and 22, and occasionally 23, carry a deep secondary constriction in the proximal third of the long arm. An idiogram of the haploíd chromosome set is presented incorporating measurements of 35 analyzed nuclei.
Investigation with Tritiated Thymidine of the Relationship Between the Sex Chromosomes, Sex Chromatin, and the Drumstick in the Cells of the Female Nine-Banded Armadillo, Dasypus novemcinctus
Authors: Grinberg M.A. , Sullivan M.M. , Benirschke K.
Published: April 2008

The functional analogies between the sex chromosomes, sex chromatin, and the drumstick in the cells of the female nine-banded armadillo (Dasypus noυemcinctus) were investigated utilizing tritium labelled thymidine both in vitro and in vivo. Tissue culture studies demonstrated that one of the female X chromosomes is asynchronous and synthesizes DNA later than the other X and most of the autosomal complement. In interphase nuclei a peripheral focus of heavier labelling was found overlying the Barr body, indicating that the sex chromatin is formed by a great part or all of the late replicating X chromosome. Localized labelling was also observed over several drumsticks in studies performed in vivo supporting the view that a relationship exists between the drumstick and the asynchronous X chromosome.
Chromosome Analysis of Four Species of Marmosets (Callithrix jacchus, Tamarinus mystax, Tamarinus nigricollis, Cebuella pygmaea)
Authors: Wohnus J.F. , Benirschke K.
Published: April 2008

A composite idiogram is presented for four species of marmosets (Callithricidae): Callithrix jacchus, Tamarinus mystax, Tamarinus nigricollis and Cebuella pygmaea. Similarities and differences are indicated where they exist in the idiograms. Analysis of the chromosome complement of C. pygmaea indicates that centric fusion between two chromosomes may have occurred during the evolution of this species.
Computer-Oriented Analysis of Human Chromosomes. I. Photometric Estimation of DNA Content
Authors: Mendelsohn M.L. , Conway T.J. , Hungerford D.A. , Kolman W.A. , Perry B.H. , Prewitt J.M.S.
Published: April 2008

The potential value of DNA content as a parameter for karyotype analysis is presented, and a method is developed based on optical density measurements of gallocyanin-chrome alum stained chromosomes. The optical information is obtained automatically in digital form by CYDAC, a special purpose cytophotometer. A partly automated computer analysis of the data then provides the relative stain content of individual chromosomes and chromosome arms. Experience with three metaphases from the same human female indicates stable clustering of the results, with sufficient discrimination among clusters to identify eleven discrete chromosome classes. It would appear from the values obtained that gallocyanin-chrome alum stain content of individual chromosome arms correlates closely with length and ultraviolet absorbance values given in the literature. It is not yet clear whether stain content represents DNA content alone, or includes other constituents of the chromosome that tend to be proportional to DNA content. Judging from the analysis of errors, improvement in the resolution of the photometric method can be expected. This approach has promising applications in the automation of karyotype analysis and as an additional and powerful parameter in cytogenetic study.
Chromosomes of Testicular Teratomas
Authors: Galton M. , Benirschke K. , Baker M.C. , Atkin N.B.
Published: April 2008

Eight testicular teratomas arising in proven males were examined for nuclear sex chromatin. Nuclear DNA content was measured in seven of the tumors and attempts were made to study the karyotype in seven and the chromosome late-replication pattern in five. Sex-chromatin-positive stromal, endothelial and epithelial cells possessing near-diploid or near-triploid DNA values were present in five of the eight tumors. Aneuploid DNA values of chromatin-negative regions corresponded with the aneuploid karyotype found in six tumors. The modal chromosome numbers ranged from 53 to 111 Not only was there marked karyotypic instability within each tumor but there was no overall similarity between different tumors. The terminal sequence of chromosome replication, successfully studied in two cases, one of which possessed sex-chromatin-positive cells, failed to reveal a late-replicating X-chromosome. Unfortunately, it was impossible to prove that the chromatin-positive teratoma did not contain a second X-chromosome: the failure to demonstrate an unequivocal XX sex chromosome constitution might be connected with special cultural requirements of the sex-chromatin-positive cells. However, other varieties of embryonic and undifferentiated cell tumors in males have been reported to display nuclear sex chromatin, and even certain normal testicular elements are sex-chromatin-positive. It is concluded that the existence of sex-chromatin-positive teratomas in males does not necessarily imply production from haploid gametes. The present observations do not rule out gametal origin. However, they provide more support for the idea that teratomas arise from diploid cells, possibly misplaced blastomere or primordial germ cells.
DNA Replication Patterns of the Sex Chromosomes of the Pigeon (Columba livia domestica)
Authors: Galton M. , Bredbury Patricia R.
Published: April 2008

The late replication pattern of the pigeon chromosomes was studied by means of the technique of terminal uptake of tritiated thymidine and autoradiography. The W-chromosome in the female completed replication after the other macrochromosomes. The Z-chromosome in the female and both Z-chromosomes in the male terminated DNA synthesis at the same time as the remaining macrochromosomes. The microchromosomes were later replicating than the macrochromosomes. It is inferred that late replication, at least in the case of the W-chromosome, signifies genetic inactivation in somatic cells. The absence of asynchronous replication of a Z-chromosome in the homogametic sex suggests that sex determination in the pigeon might depend on a gene dosage mechanism similar to that responsible for the ‘autosexing’ phenomenon.
Centric Fusion of Chromosomes in a Set of Bovine Triplets
Authors: Herschler M.S. , Fechheimer N.S.
Published: April 2008

A centric fusion of two acrocentric autosomes, forming a ‘new’ sub-mediocentric autosome, was observed in the leukocytes of female origin of a set of bovine triplets with chorionic vascular anastomosis in utero. No abnormal condition, associated with the chromosomal anomaly was discovered. It is suggested that the centric fusion is of the classical type that has in some cases been associated with species differences among the Chordata and Arthropoda.
Intraindividual Chromosomal Polymorphism in Green Sunfish (Lepomis cyanellus) as Evidence of Somatic Segregation
Authors: Beçak W. , Beçak M.L. , Ohno S.
Published: April 2008

Of 30 adult specimens of green sunfish, Lepomis cyanellus, obtained from a fish farm in southern California, 16 were heterozygous for a single Robertsonian translocation while 12 carried no translocation; the remaining two were homozygous for a translocation. In each heterozygote, the three cell types coexisted: the original heterozygous set (2n = 47, one metacentric) and the two homozygous sets (2n = 48, no metacentric, and 2n = 46, two metacentrics). No intraindividual chromosomal polymorphism was evident in those specimens which carried no translocation as well as in those which were homozygous for a translocation.
Autosomal Translocations Causing Male Sterility and Viable Aneuploidy in the Mouse
Authors: Lyon Mary F. , Meredith R.
Published: April 2008

In previous experiments on the induction of translocations in the mouse tests were usually confined to the sons of treated animals. In the present experiment daughters of irradiated males were studied, with a view to finding the frequency of X-linked translocations and of autosomal aberrations causing male sterility. The treated males were given 600 rad X-rays to the hind part of the body and offspring were obtained in the pre-sterile period. Forty-six of the 168 daughters studied were semi-sterile, and, of these, 26 carried translocations causing semi-sterility in both sexes, five carried translocations causing semi-sterility in females and full sterility in males and five had translocations giving some semi-sterile and some sterile males. All the translocations were autosomal. The five translocations causing male sterility were studied more fully. All gave chain quadrivalents and some univalents at male meiosis, and three out of four showed recognisably abnormal chromosomes at mitosis. An unexpected finding in two of the translocations was the occurrence of live adult mice with 41 or 39 chromosomes. The extra or absent chromosome was thought to be one of the translocation products. Two of the aneuploid types were associated with mild phenotypic abnormality, and in all cases the males were sterile and the females had reduced fertility. This is the first report of autosomal translocations causing male sterility and of inherited autosomal aneuploidy in the mouse.
Intrasubspecific and Intersubspecific Chromosomal Polymorphism in Peromyscus maniculatus (Deer Mouse)
Authors: Sparkes R.S. , Arakaki D.T.
Published: April 2008

Cytogenetic studies of three subspecies of the deer mouse, Peromyscus maniculatus rubidus, P.m. gracilis and P.m. bairdii have demonstrated an intra- and intersubspecific chromosomal polymorphism in which the karyotypic patterns vary among individuals of the same and different subspecies while maintaining a diploid number of 48 and a constant karyotype in each animal. Present information suggests that pericentric inversion seems the best explanation for this polymorphism.
A B-Group Ring Chromosome with Mosaicism in a Newborn with Cri du Chat Syndrome
Authors: Steele M.W. , Breg W.R. , Eidelman A.I. , Lion D.T. , Terzakis T.A.
Published: April 2008

An instance of a B-group ring chromosome with a unique mosaic pattern occurring in a newborn with cri du chat syndrome is described in detail. The patient initially demonstrated mosaicism with 98% of cells having 45 chromosomes and one ring and 2% having 46 chromosomes and no ring. Reasons for this mosaic pattern are discussed. The ring chromosome seemed stable in size but decreased in frequency as the patient aged. Autoradiographic studies on this ring chromosome, as reported by Miller et al. (1966), did not clearly indicate whether it was one of the late or early replicating B chromosomes. Dermatoglyphic and blood grouping studies are presented.
DNA Content and Size of Sex Chromatin Positive Female Nuclei During the Cell Cycle
Authors: Klinger H.P. , Schwarzacher H.G. , Weiss Jane
Published: April 2008

Relative nuclear DNA content and nuclear area were determined in fast growing, karyotypically normal, fibroblastic cell cultures derived from five human females. In two cultures H3 thymidine autoradiographic and photometric determinations were combined on the same nuclei. This allowed the separation of nuclei into three groups: those with the lowest mean DNA values which did not take up H3 thymidine are in the G1 period (2d group); those with intermediate DNA values which did take up thymidine are presumably synthesizing DNA and are in the S period; those which have double the mean 2d group DNA value and did not take up thymidine are a mixture of nuclei in the G2 period with some true tetraploids 4d group). The overall frequency of sex chromatin positive nuclei in the cultures studied ranges from 64 to 78%. Sex chromatin positive nuclei occur with about the same frequency in 2d and S nuclei but are somewhat more frequent in 4d nuclei. In three cultures the relative DNA content of sex chromatin was determined. Sex chromatin of 4d nuclei contain about twice as much DNA as those of 2d nuclei; the DNA content of sex chromatin of S nuclei is between that of 2d and 4a nuclei but closer to the mean 2d value. Sex chromatin can be identified in labelled S nuclei. These observations clearly indicate that the condensed, sex chromatin forming X chromosome does not despiralize completely during DNA replication as some authors have suggested. The DNA content of sex chromatin positive and negative nuclei is identical within each nuclear group. The areas of sex chromatin positive 2d group nuclei are larger than for negative nuclei, but this difference is only significant in one of the cultures where a large number of nuclei were measured. It is concluded that failure of the X chromosome to condense in some nuclei of females is not related to DNA
Barr Bodies in Relation to DNA Values and Nuclear Size in Cultured Human Cells
Authors: Mittwoch Ursula
Published: April 2008

The DNA values, in arbitrary units, have been measured in human fibroblast-like cells grown in tissue culture. Three cultures were available. Each cell nucleus was further classified according to the presence or absence of Barr bodies, or the presence of multiple chromocentres. Nuclear areas were also measured. The DNA values of all cultures fell into two main classes, which were interpreted to represent nuclei before and after DNA synthesis respectively. A smaller number of cells with intermediate DNA values were presumed to be in the process of DNA synthesis. It was found that the incidence of Barr bodies was higher in cells which had completed DNA synthesis than in those with the basic DNA value. In cells with intermediate DNA values, the incidence of Barr bodies was higher than in cells with the basic DNA values but lower than in cells which had completed DNA synthesis. These results are in agreement with those of other workers who found that the Barr body is not absent throughout DNA synthesis. In all DNA classes, nuclei with multiple chromocentres were the smallest, and cells with a single Barr body were smaller than those lacking a Barr body. The mean nuclear areas rose stepwise with each DNA class, although there was considerable intra-class variation.
A Test of Distributive Pairing Between Two Specific Non-Homologous Chromosomes in the Mouse
Authors: Cattanach B.M.
Published: April 2008

The possibility that the distributive pairing mechanism which operates in Drosophila melanogaster meiosis may also operate in mammals and be a causal factor in the production of aneuploidy was tested in the mouse. This was done by determining the segregation of the single maternal X-chromosome and the T6 translocation among the offspring of XO females heterozygous for the translocation. Although the appearance of animals partially trisomic for the chromosomal material of the T6 marker chromosome substantiated existing cytological evidence that the T6 marker chromosome is frequently present as a univalent in the meiotic divisions of translocation heterozygotes, no evidence for the distributive pairing of the univalent X with the univalent marker was obtained. The results do not, therefore, support the concept that distributive pairing may occur between non-homologous chromosomes in the mouse.
Three Cases of Triploidy in Man
Authors: Edwards J.H. , Yuncken Catherine , Rushton D.I. , Richards Susan , Mittwoch Ursula
Published: April 2008

A premature baby of 32 weeks gestation and weighing 1.7 kg (3 lb 12 oz), with a defect in each iris and anomalous genitalia, showed XXY triploidy on chromosome analysis. Extensive blood grouping was consistent with both digyny and diandry, but the former was more likely. Two abortuses, received as part of a survey of spontaneous abortions, revealed XXX triploidy on tissue culture. One showed a fusion defect of the neural tube; both showed late or defective fusion of the embryonic cleft of the iris. In both a small proportion of nuclei in the amnion showed two Barr bodies. In two cases in which measurements of nuclear volume were made this was about 50% greater than in diploid controls.
Sex Chromatin, Nuclear Size and the Cell Cycle
Authors: Comings D.E.
Published: April 2008

The duration of the periods of the cell cycle in a culture of human female fibroblasts was determined by tritiated thymidine autoradiography. The S period was 7.5 h, the G2 period was 5 h and the Gt period was 8.5 h. In all the monolayer cultures studied, only about one fourth of the cells were actively proliferating. The remaining cells were in a resting, or G₀, stage. If a cell culture was exposed to tritiated thymidine for 30 min, labeled cells were in the S period and unlabeled cells were in the G2, G1 or G₀ period. If exposed for 5 h, labeled cells were in the S or G2 period and unlabeled cells were in the G: or G₀ period. If exposed for 13.5 h, labeled cells were in the S, G2 or G: period and unlabeled cells were in the G₀ period. When the autoradiograms were exposed for only one to three days, the presence or absence of a sex chromatin body or condensed nuclear chromatin in both labeled and unlabeled cells could be determined. In this manner the status of the nuclear chromatin and the nuclear size of cells could be assessed during the various portions of the cell cycle. The following observations are based on the study of more than 12,000 XX, XXXXY and XY fibroblasts. (1) The percentage of sex chromatin positive cells did not vary significantly during any of the periods of the cell cycle. This indicated that the sex chromatin body underwent DNA replication without loss of its heterochromatic coiling and suggested that the inactive X chromosome did not become active during any specific portion of the cell cycle. (2) Non-specific condensed coiling of nuclear chromatin occurred most often in actively proliferating fibroblasts and least often in resting cells. The distinction between non-specific condensed coiling of chromatin and heterochromatin is emphasized. (3) The most significant factors which appeared to affect nuclear size were: (a) following cell division, nuclei tended to be small and have condensed chromatin; and (b) resting cells, which were presumably metabolically hypoactive, tended to have a larger nuclear size. The latter may have been the result of greater distention during fixation. When these two factors were excluded, there was no significant difference in the size of sex chromatin positive and sex chromatin negative nuclei. (4) The area of the sex chromatin body increased significantly following DNA replication, while the area of the nucleus did not. This suggested that the area of the tightly coiled sex chromatin body was closely related to its DNA content, while the area of the nucleus containing loosely coiled chromatin was more closely related to the tertiary folding of the chromatin than its DNA content. The nature of sex chromatin negative cells is discussed. It is proposed that they represent the loss of heterochromatic coiling without the loss of genetic inactivation.
A Malformed Boy with Double Aneuploidy and Diploid-Triploid Mosaicism 48, XXYY/71, XXXYY
Authors: Schmid W. , Vischer D.
Published: April 2008

An 11-month-old boy is described with severe developmental retardation, colobomata of both eyes, peculiar facies, syndactylies of the fingers and multiple minor malformations. Lymphocyte cultures showed the karyotype 48, XXYY, whereas, a skin fibroblast culture gave a mixture of diploid and triploid cells with the karyotypes 48, XXYY and 71,XXXYY respectively. In the triploid cell line only one of the three X chromosomes is allocyclic, as demonstrated by H3-TdR labeling and by sex chromatin studies.
Two Heterozygous Females of Mus (Leggada) minutoides musculoides Temm. with a Partially Deleted X Chromosome Arm
Authors: Matthey R.
Published: April 2008

In his previous publications (Matthey, 1963–1966), the author has studied 26 individuals of the pigmy-mouse, Mus (Leggada) minutoides musculoides Temm., from different countries of Africa. This subspecies appears as a polymorphic Robertsonian system: the diploid numbers are equal to 22, 31, 32, 33, 34, while the number of major arms (N.F. = fundamental number) is constant, i.e., 36. The X chromosome is large and nearly metacentric, the Y large and submetacentric. It is demonstrated that these sex chromosomes are formed of an acrocentric X and Y (like those of the domestic mouse) translocated onto two homologous autosomes, which, at meiosis, furnish the pairing segments associated through a true chiasma. No variation of this pattern has been detected. In another species, Mus (Leggada) triton Th., the X chromosome is submetacentric (centromeric index, approximately 0.33), the Y short and acrocentric. In a sample from Bukavu (Congo), 11 females out of 21 show only one typical X, the other X is acrocentric and its length is equal to the length of the long arm of a normal X. The deletion of the short arm is also total or subtotal. No deletion occurs in the 18 males. Recently, five musculoides were obtained from the Ivory Coast. The three males, with diploid numbers of 34, 32, 32, are very similar to seven other specimens of the same country. Both females (2N =32) show only one normal metacentric X chromosome. The other X is submetacentric (I.C. = approximately 0.26) and appears to have lost the major part of one arm. Because of insufficient material, it is not possible to establish whether females homozygous for this deletion and males with the sex chromosome constitution Xd-Y occur in the population.
The Somatic Chromosomes of Five Crocodilian Species
Authors: Cohen M.M. , Clark H.F.
Published: April 2008

The somatic karyotypes of five crocodilian species are described. These species include Caiman sclerops (spectacled caiman or South American alligator, 2N = 42), Alligator mississippiensis (North American alligator, 2N == 32), Crocoa¦ylus porosus (salt-water crocodile, 2N = 34), Crocodylus niloticus (Nile crocodile, 2N = 32), and Tomistoma schlegeli (false gavial, 2N = 32). Metacentric, submetacentric and telocentric chromosomes were observed in all species tested. Satellites were observed on a submetacentric element of A. mississippiensis, and the apparently identical chromosome with an obvious secondary constriction was found in both C. porosus and C. niloticus. No microchromosomes were found. Possible pathways of chromosomal evolution to explain the observed karyotypic relationships are suggested.
The Length of the Human Y Chromosome
Authors: Unnérus Viveca , Fellman J. , de la Chapelle A.
Published: April 2008

The length of the human Y chromosome was measured and compared with the mean length of the group E (16–18) chromosomes in ten cells from each individual in the following groups of subjects: 30 control individuals; nine members of three randomly chosen families; ten members of four families with extremely long Y chromosomes; and ten members of three families with extremely long Y chromosomes and a G-trisomic index patient. Measurements were performed a second time on three individuals from the control sample. The results obtained were treated statistically and the following conclusions could be drawn: (1) Analysis of variance indicated good reliability of the method. The mean value of the standard deviations for the variation of the duplicated measurements was 0.027. (2) Although there was a slight intercell variation within the individual, the coefficient of variation was below 5% in all 59 individuals involved in the study. Thus, the length of the Y chromosome was constant within the individual. (3) In the control population there were highly significant interindividual differences, the mean values ranging from 0.55 to 0.88 (Y/E ratio). Although a mean value for the population can be calculated (0.7306 ± 0.012), this mean has little significance because of the wide variability in the length of the Y chromosome. The distribution is of a Gaussian type without step formation. (4) No family showed any statistically significant interindividual variation. It thus could be concluded that the Y chromosome is inherited at a constant length. This applies to randomly chosen families, families with extremely long Y chromosomes and families with long Y chromosomes in which there is an index patient with G-trisomy as well. That such a wide variation in the length of the human Y chromosome is possible can be ascribed to its heterochromatic condition, its presumed paucity of genes and that the greater part of it remains unpaired at meiosis.
XX/XY Chimerism in a Tricolored Male Cat
Authors: Malouf Najla , Benirschke K. , Hoefnagel D.
Published: April 2008

A male calico cat was studied cytogenetically and found to have a 43%/57% XY/XX cellular admixture that is thought to have arisen by chimerism. The percentage of XY cells varied in the tissues examined (testes, blood and kidney). Normally descended testes were found which were composed of sterile and fertile seminiferous tubules. The latter had active spermatogenesis and spermatozoa were present in the epididymis, thus accounting for the possibility of ‘fertile calico males’. No female genital structures were present.
Chromosome Studies in 14 Cases of Intersex in Domestic Mammals
Authors: McFeely R.A. , Hare W.C.D. , Biggers J.D.
Published: April 2008

The anatomic and cytogenetic findings on 14 intersex animals, including four dogs, four cattle, three goats, two pigs and one cat, are described. Possible explanations of the observed differences between the genetic, gonadal and phenotypic sexes, including a new hypothesis, are discussed.
Autoradiographic Investigations of Centric Fragments and Rings in Patients with Stigmata of Gonadal Dysgenesis
Authors: Cohen M.M. , Sandberg A.A. , Takagi N. , MacGillivray Margaret H.
Published: April 2008

Four patients with various phenotypic stigmata of gonadal dysgenesis are presented. Cytogenetic investigation revealed each to be mosaic for 45 XO and 46 XO+ minute element stemlines. In two patients the additional element proved to be a small ring, and in the remaining two the supernumerary chromosome was a minute centric fragment. Autoradiographic studies indicated that the ring chromosomes were late replicating, while the metacentric fragments were not. The correlation of the autoradiographic behavior of these abnormal chromosomes with their possible origin is discussed, and a new hypothesis concerning the evolution of the XO karyotype is proposed.
The Chromosomes of the Field Mouse Akodon azarae (Cricetidae, Rodentia) with Special Reference to Sex Chromosome Anomalies
Authors: Bianchi N.O. , Contreras J.R.
Published: April 2008

The chromosomes of the field mouse Akodon azarae have been investigated. In males the diploid chromosome number is 38, with XY sex chromosomes. The four types of chromosome constitution in females are as follows: (a) 38 chromosomes with XX sex chromosomes; (b) 38 chromosomes Xx, the x being a grossly deleted X chromosome; (c) 38/37 Xx/XO sex chromosome mosaic; and (d) 37 chromosomes with an XO sex chromosome complement. This variability in females is believed to result from a dosage compensation mechanism ranging from X chromosome inactivation to total elimination of the X chromosome.
Leucocyte Cultures in Five Strains of Mice
Authors: Ray M. , Birnie W.A.
Published: April 2008

Leucocytes of five inbred strains of mice (LG, Swiss, SM, C3H and C57) were separated from whole blood by using 6% dextran and then grown in tissue culture medium in the presence of PHA and fetal calf serum. Transformation occurred in all strains, but mitotic divisions were observed only in the LG and Swiss strains at a maximum on the second day of culturing. The maximum mitotic index was 3.4% in both strains. The addition of human AB serum to the cultures increased the death rate of the cells and there was no mitosis.
Heterozygous Chromosomal Aberrations in the Viable Offspring of X-Irradiated Male Newts (Pleurodeles Waltlii Michah)
Authors: Jaylet A. , Bacquier Colette
Published: April 2008

The offspring of irradiated male newts were studied with a view to finding chromosomal aberrations. Several male newts (Pleurodeles waltlii) were given from 250 to 500 r X-rays to the hind part of the body and immediately placed with an unirradiated female. The proportion of abnormal embryos obtained from these matings was very significant. It was decided to investigate the viable offspring of irradiated males and to determine the types of chromosomal aberrations that they carried. This paper describes the first results obtained on 80 viable metamorphosed animals. Six animals with chromosome aberrations were studied in detail. They had translocations and deletions.
The Cytological Sex of a Bovine Anidian (Amorphous) Twin Monster
Authors: Dunn H.O. , Lein D.H. , Kenney R.M.
Published: April 2008

Two types of tissues from a bovine anidian monster were cultured for karyotyping. Only the female sex chromosome complement was observed in 162 metaphases. The modal number of chromosomes in 38 photographed metaphases was 61. There was a large unpaired acrocentric chromosome in 60, XX and 61, XX cells. Two explanations for the presence of this unpaired autosome are given. In 373 metaphases from a leukocyte culture of the monster’s normal male twin, only the XY complement was observed and the modal chromosome number was 60. The monster and its twin were dizygotic twins of unlike sex without blood cell chimerism. The possible origin of the monster is discussed.
Debut and Accumulation of Centric Fusion Products: An Index to Age of Certain Cell Lines
Authors: Nelson-Rees W.A. , Kniazeff A.J. , Darby, Jr. N.B.
Published: April 2008

Fourteen cell lines derived from cattle (Bos taurus), sheep (Ovis arks), goat (Capra hircus) and dog (Canis familiaris) were studied at various passage levels and compared chromosomally. Of these lines, those derived from the three species of Bovidae showed a similar pattern in acquisition, maintenance and increase in numbers of unusual atelocentric chromosomes with passages in vitro, while the dog cell line appeared to follow a different pattern.
Uniformity of karyotypes in the Camelidae
Authors: Taylor K.M. , Hungerford D.A. , Snyder R.L. , Ulmer, Jr. F.A.
Published: April 2008

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 examined.
The control of sex chromatin
Authors: Miller O.J. , Warburton Dorothy
Published: April 2008

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.