bluuebunny/crossref_metadata_2025 huggingface dataset:
Karyologic and autoradiographic studies of the chromosomes of Rattus (Mastomys) natalensis
Authors: Huang C.C.
Published: April 2008

The chromosomes of Rattus (Mastomys) nataknsis (2n = 36) can be classified into four groups. On the basis of the location of centromeres, the 17 pairs of autosomes include three morphological groups: six pairs subterminal, five pairs submedian to median and six pairs terminal. The sex chromosomes C3nstitute the fourth group. The X chromosome is the largest and the Y is one of the largest in the entire complement. Chromosome replication patterns in R. nataknsis were studied using autoradiography after 3H-thymidine incorporation in cultured embryonic and bone marrow cells and in vivo bone marrow cells. In female cells, replication is later for one whole X chromosome, the long arm of the other X, one pair of small metacentrics and one pair of small telocentrics than for the other parts of the complement. In male cells, replication is late for the long arm of the X, the presumptive Y, and the same two pairs of autosomes as in female cells. There is no obvious difference between the replication patterns of cells in vivo and in vitro. Cell generation time, however, is shorter in vivo. The asynchronous replication patterns of the sex chromosomes in R. natalensis are similar in general but different in detail in relation to those in cultured cells of the Chinese and Syrian hamsters.
The karyotype of the Australian long-nosed bandicoot (Perameles nasuta)
Authors: Jackson L.G. , Ellem Kay A.O.
Published: April 2008

Tissue cultures were established from Australian long-nosed bandicoot pouch young. Chromosome preparations from these cultures showed a karyotype with 12 autosomes and a XX/XY sex chromosome constitution. The six auto-some pairs are individually identifiable. The morphology of each pair is described, and further uses of this interesting karyotype are discussed.
Intrafollicular overripeness and teratologic development
Authors: Mikamo K.
Published: April 2008

Intrafollicular overripeness was studied in eggs of Xenopus which had been prevented from ovulating for extended periods. When ovulation was artificially induced, a number of eggs at various degrees were released. High mortality and malformation rates were recorded. Range and types of abnormalities were much like those in other amphibians developed from eggs affected by intrauterine overripeness. This suggests that the pathological change of the ovarian eggs is very similar to that of the uterine eggs. Effects on the meiotic spindle were studied in 353 externally normal eggs that were collected from various portions of the reproductive tract. In 179 eggs which were sectioned to show the maturation spindle in side view, 3 cases in first meiotic metaphase and 20 in second metaphase exhibited abnormal chromosomal behavior. This included precocious movement of one or two undivided tetrads and dyads to the outer or the inner spindle poles and loss of polarization of the displaced chromosomes. It was suggested that these might be caused by disintegration of the spindle fibers and related to the nondisjunction of the meiotic chromosomes. In obviously degenerating uterine eggs, disintegration of the spindle fibers was evidenced by the loss of connection of spindle fibers with the central body. Degeneration of chromosomes and hypertrophy of the spindle were also characteristic in these eggs. The importance of intrafollicular overripeness of ovocytes in the etiology of human spontaneous abortion and of congenital malformation is discussed.
48, XXXX/49, XXXXX mosaic: asynchronies among the late-replicating X chromosomes
Authors: Ricci N. , Dallapiccola B. , Ventimiglia Bernarda , Tiepolo L. , Fraccaro M.
Published: April 2008

A 13-year-old girl selected for chromosome investigations because of mental deficiency and multiple malformations was found to be a 48, XXXX/ 49, XXXXX mosaic. Multiple sex chromatin bodies, up to four, were found in oral mucosa smears and in cultured fibroblasts. Two cells with drumsticks were found in scoring 1,000 granulocytes. Autoradiography revealed cells with three and with four late-replicating X chromosomes. Analysis of the patterns of replication along the individual late-replicating X chromosomes in each cell revealed a certain degree of asynchrony among them. In both types of cells, with four and five X’s, the long arms of the X were the last to terminate synthesis. In the occasional cell there was marked internal asynchrony in this respect.
Robertsonian translocations in man: evidence for prezygotic selection
Authors: Hamerton J.L.
Published: April 2008

In the present paper, additional data on the segregation of the three types of Robertsonian translocations which occur in man are considered. In both t(DqGq) and t(DqDq) there is a significant excess of balanced heterozygotes over chromosomally normal progeny among the offspring of male heterozygotes, and this is considered to provide further evidence for some form of prezygotic selection or meiotic drive (defined as the preferential recovery of one or more of the classes of gametes resulting from meiosis in a structural heterozygote) in man, the most likely mechanism being the preferential recovery of certain classes of spermatozoa. There is also a deficiency of unbalanced progeny, and the reasons for this are discussed. The frequency of spontaneous abortions among the progeny of all three translocations is not apparently increased over the frequency generally accepted for the population as a whole.
The incidence of sex chromosomal abnormalities in mentally subnormal males
Authors: Close H.G. , Goonetilleke A.S.R. , Jacobs Patricia A. , Price W.H.
Published: April 2008

The study deals with the results of a sex chromatin survey of all adult males and a chromosome survey of males selected because they were either 6 ft (183 cm) or more in height or were between 5 ft 10 in (178 cm) and 6 ft in height at an English hospital for mentally subnormal and psychiatric cases, in which a high proportion of patients are detained because of behavioural disturbances. In particular, the survey paid attention to the manner of admission and distinguished between men admitted via the Courts under the relevant sections of the British Mental Health Act of 1959 and those admitted informally. Sex chromatin of oral mucosa cells was examined in 917 men, and in 68 men chromosome analysis was conducted. Of the latter 19 were 6 ft or more in height and 49 were between 5 ft 10 in and 6 ft in height. Four of 82 men (4.7%) detained under the Mental Health Act were sex chromatin positive, by comparison with 7 of 824 (0.9%) informally admitted. Chromosome studies showed sex-chromosome aneuploidy in 5 of 19 men of 6 ft or more and in 2 of 49 between 5 ft 10 in and 6 ft. These findings are discussed in the light of other recent information on sex-chromosome aneuploidy, mental subnormality and aberrant behaviour.
Chronology and pattern of human chromosome replication
Authors: Sandberg A.A. , Takagi N. , Schmidt Mary Lou , Bross I.D.J
Published: April 2008

The chronology of DNA synthesis in homologous chromosomes was investigated autoradiographically and statistically. The statistical approach addressed itself toward establishing rigorously the occurrence of synchrony or antisynchrony in the autosomal pairs of groups A and E. In order to evaluate DNA synthesis more intimately, chromosome No. 2, whose short and long arms can be readily identified morphologically, was divided into five arbitrarily defined segments, and the autoradiographic behavior of these was determined. Neither consistent synchrony nor antisynchrony was found to characterize the group A homologs and the segments of No. 2. In contrast to the above findings, chromosomal pair 16 apparently replicated much of its DNA antisynchronously, and a suggestion of similar behavior was obtained for pairs 17 and 18. Nevertheless, exceptions for certain chromosomes at certain times in the S period were found, indicating synchrony or antisynchrony to be present under the conditions of the experiments. Even though no one simple and universal explanation appears to be compatible with the complex data presented, the results are compatible with metasynchronous replication of DNA in homologous chromosomes. This method of replication postulates a time gap of varying length between two homologous DNA loci on chromosomes, this time gap varying from locus to locus, from chromosome to chromosome and from time to time in the S period. Thus, the time length of exposure of cells to labeled thymidine plays a crucial and all-important factor in the type of data obtained autoradiographically and accounts for the diverse statements made in the literature regarding homolog replication.
Replication of human chromosomes in primary cultures of embryonic fibroblasts
Authors: Prokofieva-Belgovskaya Alexandra A. , Slezinger S.I.
Published: April 2008

The pattern of DNA synthesis in human chromosomes at the beginning and termination of the S period has been analyzed in a primary culture of embryonic fibroblasts. 3H-thymidine pulse labeling and autoradiography have been used. For analysis of intrachromosomal asynchrony of DNA replication, each chromosome was subdivided, depending on its length, into five to nine equal regions, for which the number of silver grains was determined at the beginning and termination of the S period. Four types of replication sequences of regions along the chromosome were found: (1) replication begins from both telomere regions of the chromosome and terminates in the centromere and adjoining regions (chromosomes Nos. 1 and 3); (2) replication begins in the telomere region of the long arm and terminates in the centromere region and in the short arm (Nos. 13–15, 17–18 and 21–22); (3) replication begins from the telomere regions of both arms and terminates simultaneously in all regions along the chromosome (No. 2); (4) there are two types of regions in chromosomes – telomeric and centromeric – from which duplication begins and in which it terminates, i.e., the process of DNA replication in them continues throughout the whole S period (centromere region of Nos. 4–5, 16, 17 and 19–20; telomere regions in Nos. 4–5, 17 and 18). The possible factors which control the sequence of DNA replication in regions along the chromosome are discussed.
Oogenesis in the golden hamster (Mesocricetus auratus)
Authors: Lemon J.G. , Morton W.R.M.
Published: April 2008

A study was made of the first meiotic prophase in the female germ cells of the golden hamster (Mesocricetus auratus). It was found to commence immediately after birth, and all the germ cells had entered the diplotene stage by day 9 postpartum. The period during which the germ cells synthesised DNA was determined using an autoradiographic technique, and was found to be restricted to the first four days after birth.
The pattern of protein synthesis in late S and G2 of bovine sex chromosomes
Authors: Herzog Rita , Steffensen Dale M.
Published: April 2008

The temporal relation and correlation between the syntheses of DNA and protein of bovine female sex chromosomes were studied. Significant differences were found between the patterns of protein and DNA synthesis as studied by 3H-lysine and 3H-arginine incorporation into protein and 3H-thymidine incorporation into DNA. In contrast to the late-labeling X chromosome for DNA, no X chromosome was found to be late labeling with respect to protein containing either 3H-lysine or 3H-arginine. No distinct differences were found between the patterns of incorporation of the two tritiated amino acids into the chromosome protein.
Chromosome studies of the Ainu population of Hokkaido
Authors: Hungerford D.A. , Makino S. , Sasaki M. , Awa A.A. , Balaban Gloria B.
Published: April 2008

Chromosome studies were carried out on metaphases from leukocyte cultures of 25 Ainu from Hokkaido and three Ainu, three Oroks and one Gilyak from Sakhalin. The chromosomes of four additional Hokkaido Ainu were studied in cells from skin cultures. No significant departures from the chromosome complement characterizing other human populations were detected.
Detection of minute deletions in human karyotypes
Authors: Warburton Dorothy , Miller D.A. , Miller O.J. , Allderdice P.W. , De Capoa A.
Published: April 2008

Minute deletions of the B-group short arm have been demonstrated in five of six cases with clinical features suggestive of a deletion of chromosome 4 or 5, but with grossly normal chromosomes. A deletion as small as 8% of the short arm was detectable by each of five observers when randomly arranged cells from controls, cases with large deletions and the cases with suspected minute deletions were scored blindly for the presence of a deletion. Another two cases were shown to have deletions of only 4% of the short arm by measurement studies, although the deletion in these cases could not be detected visually in the blind study. The presence of the deletion was confirmed in one case by DNA-labelling studies showing that the putative deleted chromosome consistently had the replication pattern of chromosome 4. In another two cases measurement of the long arm confirmed that the deleted chromosome was a chromosome 5.
Clustering in deleted short-arm length among 25 cases with a Bp– chromosome
Authors: Miller D.A. , Warburton Dorothy , Miller O.J.
Published: April 2008

Measurement of the B-group short arms from 25 cases and five balanced carriers with a Bp– chromosome showed a significant clustering of the size of the deleted short arm between 0.45 and 0.65 of the normal short-arm length. No differences in length were apparent among family members when the deletion was familial. The distribution of deletion size appeared similar for chromosome 4 and chromosome 5. No correlation was found between any clinical feature and the length of the deleted short arm. The results are discussed in relation to the origin of deletions – simple terminal or interstitial deletions or reciprocal translocations.
Mouse germ cells and LSD-25
Authors: Jagiello Georgiana , Polani P.E.
Published: April 2008

Acute and chronic studies of male and female meiosis in an Imperial-Chemical-Industries-derived strain of mice were carried out with LSD-25. Over a wide range of doses claimed to be effective in teratogenesis and male meiosis in the mouse and in the production of chromosome damage in leucocyte cultures of human blood, no convincing effect was detected on the chromosomes of first or second meiotic divisions, nor in those of the bone-marrow or of the few spermatogonial metaphases that were studied.
Cytotaxonomy and chromosomal evolution in Serpentes
Authors: Beçak W. , Beçak Maria Luiza
Published: April 2008

The karyotypes of 15 species of snakes are described: Lachesis muta noctivaga, Micrurus lemniscatus carvalhoi, Philodryas aestivus aestivus, P. patagoniensis, P. serra, Thamnodynastes pallidus nattereri, T. strigatus, Tomodon dorsatus, Xenodon neuiviedii, Liophis miliaris, Erythrolamprus aesculapii venustissimus, Hydrodynastes bicinctus schultzi, H. gigas, Pseustes sulphureus sulphureus and Oxyrhopus petolarius. The diploid number varied from 24 to 46 between species of the family Colubridae. During evolution, variation of the chromosome number in the suborder Serpentes occurred mostly by rearrangements of genetic material rather than by alterations of the DNA amount. Different stages of heteromorphic sex-chromosome differentiation were detected in the species analyzed; these ranged from absence of heteromorphism in either sex to striking differences in form and size of the sex heterochromosomes in the female.
DNA replication studies of human D-group chromosomes in satellite associations
Authors: Nakagome Y.
Published: April 2008

DNA replication studies were carried out on metaphase plates showing satellite associations to determine the association of individual D chromosomes. In a total of 279 D chromosomes involved in satellite associations and identified by autoradiography, it was found that the association of the three members of the D chromosomes was random. In D/D associations no prevalence of homologous combination was observed. In addition, a case of D trisomy and three cases with t(GqDq) (from two unrelated families) were studied. The extra D chromosome in the first case was identified as a No. 13 by the labelling pattern. In the other three cases, the D chromosome involved in the translocation was identified as a No. 14. Studies of satellite associations in these cases are also described.
Human chromosome analysis as computed from arm lengths measurements
Authors: Neurath P.W. , Enslein K.
Published: April 2008

Computer programs of both a statistical and logical nature were applied to the problem of human karyotyping. A linear discriminant function was calculated based on karyotyping and measurements made by an experienced cytogeneticist on 50 spreads, the design set, and this function was tested on a further 50 spreads, the test set. All the spreads used were from normal human females, but the procedure could easily be extended to male karyotyping, providing the appropriate ‘male’ or ‘female’ program is used in a given case. The only input measurements required and used in the design and test sets were the four arm lengths of each chromosome, measured and supplied to us as four single straightline segments from the centromere to the ends of the arms to simulate contemplated computer measurements. The analysis was done in two stages; the first assigned each chromosome into one of eight groups by its individual characteristics. The second reassigned the 46 chromosomes of each spread so that each group in each spread had its correct number corresponding to a normal human karyotype. The results of the first stage of the computer analysis disagreed with the cytogeneticist 8% of the time in the design set and 9% of the time in the test set. The second stage proved successful in decreasing this disagreement to 6% and 7% respectively. The discriminant function found and the reassignment algorithm can serve as a karyotyping system which is both quantitative and objective. It requires only arm-length measurements to be made. With computer assistance in making these and possible additional independent measurements, such a system appears promising as a basis for automating chromosome analysis.
Chromosomal aberrations in cultured leukocytes from pigs derived from X-irradiated semen
Authors: Zartman D.L. , Fechheimer N.S. , Baker L.N.
Published: April 2008

Fresh semen from swine was exposed to 600 r of X-irradiation and used to inseminate sows. The chromosomes of the resultant liveborn progeny were studied through the use of leukocyte cultures. Of the 31 pigs studied, 4 had consistent large aberrations in all of the 30 cells studied per animal. Three of these aberrations were translocations; the other was a pericentric inversion. These were thought to be attributable to immediate effects of X rays. An interesting mosaic condition was seen in three of the pigs studied. It was apparently inherited, at least in two of them. All of the pigs had a breakage-deletion condition for the same chromosome. Among the delayed effects of X-irradiation were chromosome alterations including aneuploidy, fragments, chromosome breaks, chromatid breaks and chromosome gaps. Other traits studied were chromatid gaps, secondary constrictions, pericentric inversions and sister chromatid fusions. The independent variables included in the analyses of variance were X-irradiation, breed, sex, irradiation × sex interaction and breed × sex interaction. The effects of these independent variables were not lucid, but there were some conclusions drawn. X-irradiation had a threshold effect, with the effect being a suppression of aberrations. Females, when interacting with the irradiation or breed effects, had higher frequencies of aberrations than males. Breed effects were not consistent, and no trend was apparent. Of the nine dependent variables studied, only fragments and chromosome breaks were noticeably correlated.
Cytogenetic and endocrine studies of a freemartin heifer and its bull co-twin
Authors: Short R.V. , Smith Janet , Mann T. , Evans E.P. , Hallett Janet , Fryer Anthea , Hamerton J.L.
Published: April 2008

The study of a bovine freemartin and its male co-twin has shown that the sex-reversed gonads of the female are secreting testosterone. Therefore, we suggest that the masculinisation of the freemartin’s reproductive tract may be due to sex hormones secreted by its own gonads, rather than by those from its male co-twin. On the evidence at present available, we favour the view that the female gonad is sex-reversed by a humoral inductor substance coming from the male co-twin that causes retention of the medullary sex cords. A study of the male co-twin suggests that its gonads may also be abnormal in that they secrete reduced amounts of androgen. Both twins showed extensive 60, XX/60, XY chimaerism, with a metacentric marker chromosome associated with the XY cell line only. This was derived from the dam. The proportion of XY cells varied markedly between tissues in both the twins. We were unable to find any germ cells in the female gonad, and, with the exception of one possible female pachytene, all the germ cells examined in the male’s testes were XY.
The length of secondary chromosomal constrictions in normal individuals and in a nucleolar mutant of Xenopus laevis
Authors: Rafferty, Jr. K.A. , Sherwin R.W.
Published: April 2008

Secondary chromosomal constrictions are thought to be the loci of the genome which code for ribosomal RNA synthesis. Their metaphase length could depend on nucleolar size or level of functional activity in interphase or on gene content. Wild-type frogs and a frog heterozygous for the Oxford nucleolar mutation were studied to determine which possibility is more probable. The mutant was studied because its single nucleolus is larger than wild-type nucleoli, it has only one constriction, half as many ribosomal genes, but produces the same amount of ribosomal RNA. The results indicate (1) that constriction length depends on the amount of genome (whereas others have shown nucleolar size to be related to level of activity) and (2) that the deletion is limited to the constricted segment, supporting the view that the constriction is the nucleolar organizer. Also, metaphase constrictions are longer than expected from their DNA content.
Differential transmission of translocations induced in spermatogonia of mice by irradiation
Authors: Ford C.E. , Searle A.G. , Evans E.P. , West Jean
Published: April 2008

The hindquarters of two batches each of five young adult male mice were exposed to an acute dose of 1,200 R of 250-kV X-rays in two fractions of 600 R, separated by a period of eight weeks. Means of 41.2% and 32.6% spermatocytes with one or more multivalent configuration were found when the mice were killed 13 to 18 and 59 weeks, respectively, after the second dose. The multivalent configurations were attributed to reciprocal transloeations induced in spermatogonia. Other types of chromosomal abnormality were rare. 150 sons were tested for semi-sterility and subsequently examined cytologically. Five were found to be translocation heterozygotes. One other was cytologically normal but nevertheless exhibited semi-sterility and transmitted this character to some of its descendents. The frequencies of spermatocytes with various numbers and types of multivalents were used to estimate the proportions of sperm with normal, balanced translocated and unbalanced haploid genomes, and hence the expected frequencies of zygotes with abnormal karyo types. The expected frequency of semi-steriles (or translocation heterozygotes) in the progeny proved to be about twice as great as that observed in parallel genetic experiments (Lyon et al., 1964; Searle, 1964) and in the sons of the irradiated males. Expected dominant lethals were also about twice as frequent as observed by Lyon et al. Whatever assumptions are made regarding the distribution of chiasmata in the multivalents and their manner of disjunction, the observed frequencies of translocation heterozygotes or dominant lethals or both are much less than the expected frequencies. The evidence is considered to favour a selective process operating on diploid rather than haploid genomes but perhaps taking effect on the haploid spermatids or sperm.
Chromosomes of the tree shrews (Tupaiidae)
Authors: Arrighi Frances E. , Sorenson M.W. , Shirley Linda R.
Published: April 2008

Chromosomes from seven species of Tupaiidae, including Tupaia glis, T. chinensis, T. longipes, T. montana, T. minor, T. palawanensis and Urogale everetti, were analyzed. The diploid number varied from 68 for T. montana to 44 for U. everetti. T. glis and longipes had identical karyotypes and diploid numbers (2n = 60). T. minor had a diploid number of 66, and palaivanensis had one of 52. The number of biarmed chromosomes per cell varied considerably among the species studied.
Male sterility and an autosomal translocation in Romney sheep
Authors: Bruère A.N.
Published: April 2008

Five closely related Romney sheep are described. All showed centric fusion of two acrocentric chromosomes, forming a submetacentric chromosome. One sheep, a ram, had abnormally shaped testicles, was sterile and showed persistent aspermatogenesis. Meiotic chromosome studies on primary spermatocytes from this sheep showed 24 or 25 bivalents and a trivalent instead of the 27 bivalents seen in normal rams. The sex bivalent was not involved in the trivalent, which confirmed this to be an autosomal translocation. It is suggested that the sterility of this sheep was possibly genetically determined in the same way as in male mice with a similar chromosome translocation.
The temporal appearance of sex chromatin and of the late-replicating X chromosome in blastocysts of the domestic rabbit
Authors: Issa M. , Blank C.E. , Atherton G.W.
Published: April 2008

It is demonstrated that sex chromatin appears in cells of pre-implantation blastocysts of the domestic rabbit over a period from approximately 96 to 120 hours after mating of the parent animals. We are unable to confirm the observation of Melander (1962) that chromatin bridges between separating masses of daughter chromosomes at anaphase (‘anaphase bridges’) are present only in those blastocysts in which sex chromatin begins to appear. The interrelationships between nuclear size, mitotic index and the appearance of sex chromatin were studied. The sequence of DN A replication of the sex chromosomes was investigated in adult rabbit tissues and in rabbit morulae and blastocysts after, during and before the period during which sex chromatin appears for the first time. It is apparent that a late-replicating X chromosome is present in morulae before sex chromatin can be identified. Although the frequency of ceils showing a late-replicating X chromosome is correlated with stage of development, the rate of change of frequency with stage of development differs from that observed for the frequency of sex chromatin. It is suggested that the phenomena of late replication and of X-chromosome condensation in interphase are not as closely related as has previously been thought; that neither produces the other but, rather, that each is an independent effect of some physiological activity of the cell which is at present little understood.
The chromosome complement of human endometrium
Authors: Rask-Madsen J. , Philip J.
Published: April 2008

So as to clarify the conflicting data on the chromosome number of human endometrium, endometrial cells from six normal women and four patients with uterine bleeding were cultured in vitro in serial tissue culture, omitting trypsin, CO2 incubation and human serum. Based on chromosome studies of 5,301 dividing cells, including determinations of exact chromosome numbers of 2,242 metaphases and estimations of ploidy levels and complete karyotype analysis of 332 cells, normal human endometrium was shown to have the same chromosome number as other human tissues. Furthermore, the chromosomal constancy was the same as in normal skin tissue. Polyploidy incidence was higher in three patients with bleeding, and one of them had a higher degree of aneuploid variation. One patient with fibroma had only near-tetraploid cells in the sample of endometrium studied. A statistical analysis of aneuploid cells with 45 chromosomes suggested that the losses were nonrandom.
An XXY sex-chromosome constitution in a dog with testicular hypoplasia and congenital heart disease
Authors: Clough E. , Pyle R.L. , Hare W.C.D. , Kelly D.F. , Patterson D.F.
Published: April 2008

A sterile male German shorthair pointer with testicular hypoplasia and a ventricular septal defect was found to have a 79, XXY chromosome constitution in peripheral-blood leukocytes, bone marrow and fascia lata fibroblasts. The presence of a late-labeling X chromosome in peripheral-blood leukocytes was demonstrated by autoradiographic studies. This is the first report of the occurrence of the XXY condition in a dog.
The chromosomes of the order Crocodilia
Authors: Cohen M.M. , Gans C.
Published: April 2008

The somatic karyotypes of the 21 surviving species of the order Crocodilia are presented. The population surveyed totals 71 animals, with representatives of both sexes in 13 species. No karyotypic differences were observed among the multiple specimens within a given species or subspecies. There was no evidence for consistent heteromorphism that might be indicative of a sex-chromosome pair. All chromosomes possessed distinct morphology and were classified as macrochromosomes in the absence of an absolute distinction between macro- and microcbromosomes. The diploid number in this order ranges from 30 to 42; however, the fundamental number (N.F.) shows only 10% variation (56 to 62). Two obvious marker chromosomes were evident – a satellited submetacentric characteristic of alligators and a telocentric with a marked secondary constriction observed in nine species of crocodiles. Evolutionary pathways of karyotype development are discussed from the consideration of both centromeric ‘fusion’ and ‘fission’.
Maturation of the mouse oocyte in vitro
Authors: Donahue R.P.
Published: April 2008

In the course of examining about 5000 mouse oocytes maturing in vitro, three types of errors of first polar body formation, presumably spontaneous in origin, were observed: (1) twenty (0.4%) oocytes with a very large polar body possessing an organized metaphase II spindle instead of the usual scattered and degenerate polar body chromatin; (2) four (0.08%) oocytes in which two normal-sized polar bodies shared equally all the egg chromatin; and (3) one (0.02%) oocyte with all the chromatin in one group, probably representing failure of polar body formation. Large polar body formation provides a cytologic basis for those cases in man where fertilization of two egg nuclei by two spermatozoa has been postulated as the origin of certain mosaic individuals. The other two types of anomalies would presumably lead to death of the embryo.
Further studies on the sex-chromosome systems of the American leaf-nosed bats (Chiroptera, Phyllostomatidae)
Authors: Baker R.J. , Hsu T.C.
Published: April 2008

Two additional genera, Ametrida and Enchisthenes, and another species of Λrtibeus were found to have an XX/XYjY2 sex-chromosome system, bringing the total number of species possessing this system in the family Phyllostomatidae to nine. Another species (Mesophylla macconnellï) of this family has somatic chromosomes suggesting an XX/XO sex-chromosome system; however, the Y may be present in the genome but is probably translocated to an autosome. The incidence of either the XX/XY1Y2 or XX/XO? system is rare in mammals, and the presence of both types in one group of closely related forms is without precedent. Involvement of an autosome with sex chromosomes is suggested as a common factor for the two systems.
Chromosome studies of pocket gophers, genus Thomomys
Authors: Patton J.L. , Dingman R.E.
Published: April 2008

C-metaphase karyotypes from bone-marrow cells from 117 individuals representing 24 populations of the pocket gopher, Thomomys bottae (Eydoux and Gervais), were studied. The geographic range of the populations sampled was California, Arizona, New Mexico and the Mexican states of Sonora and Sinaloa. No evidence of intrapopulation variation was recorded, but extensive inter-population variation in chromosome complement was observed. All individuals, excepting one, had a diploid number of 76, so that variation rested in the relative numbers of each morphological type of chromosome in the respective complements. Existing evidence suggests interfertility between adjacent populations despite degrees of karyotypic disparity.
Polyploidy and mechanisms of karyotypic diversification in Amphibia
Authors: Beçak Maria Luiza , Denaro L. , Beçak W.
Published: April 2008

Polyploid species were described in amphibians of the family Ceratophrydidae (Procoela). Tetraploid (4N = 44) and octoploid (8N = 104) karyotypes resulted apparently by duplication of ancestral genomes with N = 11 and N = 13 respectively. The meiosis of the polyploid species was regular, producing euploid gametes. Comparative cytophotometric measurements confirmed a DNA increase in a 1:2:4 ratio, as expected from cytological observations. Fourteen species and one subspecies of the families Ceratophrydidae, Leptodactylidae, Hylidae, Brachycephalidae and Bufonidae were cytogenetically studied. New evidence for the occurrence of the polyploid process in anurans was found. Besides the polyploid Ceratophrydidae, a new polyploid species was identified in the family Hylidae, Phyllomedusa burmeisteri, a tetraploid with 4N = 52 chromosomes. Although some polyploid species were easily detected cytologically, some apparently diploid anurans exhibited DNA values suggesting previous duplications of the whole genome.
Cytogenetic study of Lemur catta
Authors: Rumpler Y.
Published: April 2008

A cytogenetic study has been made from leukocyte cultures of the peripheral blood of 10 males and 16 females of L·emur catta, an endemic species of Madagascar. The animals had been provided from different parts of Madagascar. All the animals have been found to possess 56 chromosomes; yet females have four metacentric chromosomes and males only three. This suggests that the X chromosome of L·emur catta is a metacentric chromosome. The result is compared with previous studies.
Etiology of nondisjunction: lack of evidence for genetic control
Authors: Juberg R.C. , Davis Louise M.
Published: April 2008

Evidence for genetic control of meiotic nondisjunction was not found in a religious isolate of Amish in northern Indiana. Sixteen mongols were ascertained, and each had 47 chromosomes without evidence of mosaicism. Through the use of detailed family records, pedigrees were assembled for the propositi. The 16 comparison sibships were matched for maternal age and sibship size and selected at random from the same population. Mean inbreeding coefficients for the parents, grandparents, and great-grandparents were not significantly different between the two groups.
Pericentric inversion of a number 15 chromosome in nine members of one family
Authors: Crandall Barbara F. , Sparkes R.S.
Published: April 2008

A pericentric inversion of a group D chromosome was found in a phenotypically normal nine-year-old boy in the course of a chromosome survey of children with behavioral disorders. Family studies demonstrated its presence in eight other individuals, all of whom were also phenotypically normal. Autoradiographic studies suggested that the inversion involved the No. 15 chromosome. Evaluation of 17 gene markers failed to establish linkage of their genetic loci to the inverted No. 15 chromosome.
Autoradiographic identification of a 13/21 translocation
Authors: De Capoa Adriana , Rocchi Angela
Published: April 2008

We have studied by means of autoradiography a case of D/G translocation after terminal labelling of leukocyte cultures with 3H-thymidine. The D-group chromosome involved in the translocation has been identified as a No. 13 and the G-group chromosome as a No. 21. This is the first case of a 13/21 translocation over a published total of 40 cases.
Combined interactive computer measurement and automatic classification of human chromosomes
Authors: Neurath P.W. , Ampola Mary G. , Low D.A. , Selles W.D.
Published: April 2008

A computer system to both measure and classify human chromosomes with good accuracy compared to manual methods is described. Using a 35-mm photomicrographic negative, the system, while measuring the chromosomes automatically, requires a human operator’s interaction for about 15% of the chromosomes. Results for an initial 45 spreads are given. Using the interactively measured arm lengths and arm areas, the system classified over 99% of the chromosomes correctly into 10 classes without any assistance; two chromosomes, or 0.1% of the initial sample, were misclassified (from group D to E). For the remaining 1%, interaction after classification was requested by the computer, and, with the information available to the operator, a correct classification can be made in these cases by him. The system uses a computer-controlled flying spot scanner connected to a medium-size general purpose computer, an IBM 360 Series, Model 30, and takes 25 min per spread. An annual capacity of 7500 analyzed spreads will be available in 1971 after installation of an RCA Spectra 70/46, operating under a multi-programmed system, in October 1970. Applications for the system may depend on cytogeneticists exploiting its advantages and avoiding the drawbacks described.
The chromosomes of 14 species of amphisbaenians (Amphisbaenia, Reptilia)
Authors: Huang C.C. , Gans C.
Published: April 2008

The chromosomes of 14 species belonging to eight amphisbaenian genera are here reported. The karyotypes of nine species all comprise 6 pairs of metacentric macrochromosomes (M) and 7 to 12 pairs of microchromosomes (m). The M in these species are similar to one another in morphology. One species, Geocalamus acutus, has 7 pairs of M and 12 pairs of m; two of the M are telocentric, perhaps as a result of centric fission of one pair of metacentric M. The remaining four species, Bipes biporus, Amphisbaena alba, A. fuliginosa, and A. innocens, had higher diploid numbers and wide variations in morphology. B. biporus had 10 pairs of biarmed M and 11 pairs of m. A. alba had 11 pairs of M, 7 biarmed and 4 telocentric, and 8 pairs of m. A. fuliginosa had 11 pairs of M, only 3 biarmed and 8 telocentric, and 13 pairs of m. A. innocens also had 11 pairs of M, 4 biarmed and 7 telocentric, and 14 pairs of m. The karyotypes of these four species are so different from one another and from those of the remainder of the group that it was not possible to assess their cytogenetic relationships. A distinct and independent sequence of chromosomal evolution was presumably involved in each case. No heteromorphic pair or monosomy was observed in either male or female amphisbaenians.
Chromosome structure and function in man
Authors: Hungerford D.A. , LaBadie Gundula U. , Balaban Gloria B.
Published: April 2008

Provisional maps are given for the two smallest autosomes (chromosomes 21 and 22) at pachytene in the human male. The longer of the two consists of 10 chromomeres in a standard sequence of various sizes, and the shorter one of 6 such chromomeres, including in each case the large terminal chromomere within which the centromere is located. With increasing compaction many of the details of these chromomere patterns disappear. Nevertheless, the two bivalents remain distinguishable from each other by their having, in addition to the large terminal chromomere, three and two major markers, respectively. Maps are given both at the extended and compacted stages.
Localization of heterochromatin in human chromosomes
Authors: Arrighi Frances E. , Hsu T.C.
Published: April 2008

Heterochromatic regions in chromosomes of man, mainly at the centromeric areas, can be demonstrated with consistency using a special staining procedure. This procedure includes treatments of cytological preparations with HCl, RNase, NaOH (denaturing DNA), and renaturing DNA in a saline citrate solution at 65°C. The heterochromatic regions can be observed after staining with Giemsa. These regions are believed to be composed of constitutive heterochromatin. Facultative heterochromatin regions, e.g., the repressed X in female cells, do not respond to this series of treatments.
Autoradiographic studies on an X-autosomal translocation in man: 45, X,15–, tan(15qXq+)+
Authors: Engel W. , Vogel W. , Reinwein H.
Published: April 2008

In a female infant exhibiting cleft palate, hydrocephalus communicans, vitium cordis congenitum, and other anomalies, chromosome analysis revealed a C/D translocation. According to its replication pattern, the translocation chromosome comprised almost a whole X and the long arm of a chromosome 15. In accordance with the Lyon-hypothesis, in a number of the cells the translocated X, Xt, or the normal X, Xn, was the late-replicating chromosome. In a few cells both Xt and Xn were late labeled, which was interpreted as perhaps the result of somatic segregation. In some of the cells showing a late-replicating Xt, the autosomal segment, which is normally early replicating, was labeled; this observation was interpreted as a position effect. The genetic material lost comprised the product of the reciprocal translocation, consisting of the centromeric region of chromosome 15 and the telomeric region of the long arm of the X. The severe clinical anomalies of the patient were ascribed to the inactivation of the translocated autosomal segment observed in a part of the examined cells.
Sex-chromosome mosaicism in pouch young of marsupials Perameles and Isoodon
Authors: Walton Shirley M.
Published: April 2008

In 0- to 2-day-old bandicoots (Perameles nasuta and Isoodon obesulus) both sex chromosomes were retained in all skin and gut cells examined. Elimination of one X chromosome had occurred in some spleen cells and in all liver cells examined in a 10-day-old female P. nasuta. In a 24-day-old male I. macrourus the Y chromosome was absent in all (three only) spleen cells examined and in more than half of the liver cells. Both X chromosomes were present in all corneal cells of a 55-day-old female I. macrourus, but in the same animal only one X was present in all spleen and bone-marrow cells examined. Sex-chromosome elimination in bandicoot tissues occurred at much later stages of morphogenesis than does the appearance of sex-chromatin bodies in the cells of eutherian mammal embryos. Thus sex-chromosome inactivation probably occurs much later in bandicoots than it does in eutherian mammals.
Unusually large sex chromosomes: new methods of measuring and description of karyotypes of six rodents (Myomorpha and Hystricomorpha) and one lagomorph (Ochotonidae)
Authors: Wurster Doris H. , Snapper J.R. , Benirschke K.
Published: April 2008

Chromosome studies of six rodents, of which three have unusually large X chromosomes, and one lagomorph have been made. Two new methods of measuring unusually large sex chromosomes are presented. Compound sex elements are more often discovered as more species are studied, but the phenomenon in species without an X-to-autosome translocation is thus far restricted to the Artiodactyla, Rodentia, and Marsupialia, a point discussed in the text. Eutherian mammals known to have X chromosomes of more than 6 % of the haploid complement and all members of the Hystricomorpha that have been studied karyologically have been summarized.
Human chromosome identification by differential staining: G group (21-22-Y)
Authors: Chernay Patrice R. , Hsu Lillian Y.F. , Streicher H. , Hirschhorn K.
Published: April 2008

Arrighi and Hsu (1971) have described a method of differential staining of chromosomes based on the localization of repetitive DNA associated with heterochromatin. We have employed this method in an attempt to identify human chromosomes, especially the G group, Nos. 21 and 22 and the Y. Metaphases from a patient with 47,XY,21+ were examined. In addition to the Y chromosome, which shows dense staining in its long arm, three of the five G-group chromosomes show centromeric regions that stain much more densely than those of the other two. This indicates that it is possible to differentiate chromosome 21 from 22 and the Y. The possibility of identifying other chromosomes by similar differences is a likely one.
Observations on the incidence of Robertsonian translocations and associated testicular changes in a flock of New Zealand Romney sheep
Authors: Bruère A.N. , Mills Robyn A.
Published: April 2008

In the present paper preliminary observations are described on the incidence of the Massey I Robertsonian translocation in Romney sheep. In the established “M” pedigree flock an incidence of 4.6% of translocation heterozygotes was found in 152 animals examined randomly, compared with no such translocation in 246 sheep of varying breed from several countries. From pedigree follow-up a total of 25 translocation animals were found in an overall total of 180 animals studied. The origin of the translocation can be traced to two other popular pedigree flocks, “BH” and “MDW”, so that it could be distributed extensively in the Romney breed in New Zealand. Five rams with the translocation found in the “M” pedigree flock also had testicular abnormalities. Only three rams with the translocation from the same flock had normal testes. It is suggested that a “sterility” gene, which manifests itself by incomplete testicular development, may be associated in some cases with the translocation chromosome or its homologues and be present in either translocation heterozygotes or nontranslocation-carrying animals. Ewes heterozygous for the translocation appeared phenotypically normal. From leukocyte cultures one translocation heterozygote ewe was shown to be a normal translocation mosaic. A phenotypically normal ewe was found also from the present survey with a second type of Robertsonian translocation (Massey II), involving two of the larger acrocentric chromsomes and distinct from the Massey I translocation.
Comparison of chromosomal behavior in cultured lymphocytes and fibroblasts from patients with chromosomal disorders and controls
Authors: Higurashi M. , Conen P.E.
Published: April 2008

The occurrence of satellite association, breaks, tetraploidy or endoreduplication, and structural rearrangements was studied and compared in 600 lymphocyte and 600 skin-fibroblast metaphases from 30 karyotypically normal individuals and in 820 lymphocyte and 820 skin-fibroblast metaphases from 41 patients with various chromosomal disorders. The frequency of satellite association was less (0.02 < P < 0.05) in fibroblast than lymphocyte cultures of both the control and abnormal groups. The incidence of breaks in the controls was 2.5 % in lymphocytes and 4.2% in cultured fibroblasts. In patients with chromosomal disorders, the incidence was 5.5% in cultured lymphocytes and significantly greater (P < 0.01), 15.2%, in cultured fibroblasts. The incidence of tetraploid cells (including endoreduplication) in lymphocyte cultures was 0.2% of 3000 cells in the controls and 0.3% of 4100 cells in the abnormal group; this was significantly less (P < 0.01) than the incidence in fibroblast cultures, 3.9% of 3000 control cells and 3.7% of 4100 cells in the abnormal group. The excess of breaks and tetraploid cells in cultured fibroblasts compared to cultured lymphocytes may be due to the longer duration in culture, with increased risk of chromosomal damage, of the fibroblast cultures.
Tetraploidy and 18-trisomy in a six-year-old triple mosaic boy
Authors: Atnip R.L. , Summitt R.L.
Published: April 2008

Clinical and cytogenetic studies of a six-year-old boy with multiple anomalies, including growth retardation, mild mental retardation, diffusely scattered minute areas of skin hypopigmentation, and skeletal abnormalities, are presented. Chromosomal analysis of lymphocytes, skin fibroblasts, and marrow cells showed a significant proportion of cells to have a tetraploid number of chromosomes. An extra 18 chromosome was present in approximately 10% of the cells from peripheral blood.