Showing papers on "Chromosome published in 1979"
TL;DR: It is concluded that the genes for human immunoglobulin heavy chains are located on human chromosome 14 in immunoglOBulin-producing human cells.
Abstract: We have studied somatic cell hybrids between P3x63Ag8 mouse myeloma cells deficient in hypoxanthine phosphoribosyltransferase (EC 2.4.2.8) and either human peripheral lymphocytes or human lymphoblastoid or myeloma cells for the production of human immunoglobulin chains and for the expression of enzyme markers assigned to each of the different human chromosomes. Human chromosome 14 was the only human chromosome present in all independent hybrids producing mu, gamma, and alpha human heavy chains. In two of the independent hybrids that produced human heavy chains, human chromosome 14 was the only human chromosome present in the hybrid cells. Loss of human chromosome 14 from these hybrids resulted in the concomitant loss of their ability to produce human immunoglobulin heavy chains. In view of these results, we conclude that the genes for human immunoglobulin heavy chains are located on human chromosome 14 in immunoglobulin-producing human cells.
325 citations
TL;DR: It is reported that in mouse S-180 and L5178Y cell lines unstably amplified dihydrofolate reductase DNA sequences are associated with small, paired chromosomal elements denoted "double minute chromosomes," whereas in stably amplified cells of the same origin, the genes are related with large chromosomes.
Abstract: Selection of mammalian cells in progressively increasing concentrations of methotrexate results in selective amplification of DNA sequences coding for dihydrofolate reductase (tetrahydrofolate dehydrogenase, 5,6,7,8-tetrahydrofolate:NADP+ oxidoreductase, EC 1.5.1.3). In some cell variants the amplified genes are stable with growth in the absence of methotrexate, whereas in other variants the amplified genes are lost from the population. We have previously reported that in a stably amplified variant of Chinese hamster ovary cells, the genes are localized to a single chromosome. Herein we report that in mouse S-180 and L5178Y cell lines unstably amplified dihydrofolate reductase DNA sequences are associated with small, paired chromosomal elements denoted "double minute chromosomes," whereas in stably amplified cells of the same origin, the genes are associated with large chromosomes.
307 citations
TL;DR: Experimental evidence indicates that the repeating ribosomal DNA (rDNA) genes of the yeast Saccharomyces cerevisiae are located on chromosome XII, and establishes that in mitosis most of the rDNA genes in yeast are not extrachromosomal.
Abstract: Two lines of experimental evidence indicate that the repeating ribosomal DNA (rDNA) genes of the yeast Saccharomyces cerevisiae are located on chromosome XII. First, the rDNA genes are linked mitotically to genes that have been previously mapped to chromosome XII. Second, yeast strains that have two copies of the chromosome containing the rDNA genes in every strain examined also have two copies of chromosome XII; this is not true for the other yeast chromosomes. These data also establish that in mitosis most of the rDNA genes in yeast are not extrachromosomal.
222 citations
TL;DR: The karyotypes of pristane-induced mouse plasmacytomas support the theory that the nonrandom chromosomal changes in lymphoproliferative malignancies are associated with the type of the target cell, rather than with the etiological agent.
187 citations
TL;DR: This chapter discusses the genetic control of meiosis, which presents a seemingly paradoxical situation in which universality and uniqueness are harmoniously combined.
Abstract: Publisher Summary This chapter discusses the genetic control of meiosis. Meiosis presents a seemingly paradoxical situation in which universality and uniqueness are harmoniously combined. All organisms, irrespective of their evolved complexity, meiotically reduce the chromosome number on beginning sexual reproduction. Genetic recombination and the associated cytological phenomena—chromosome pairing and formation of the synaptonemal complex (sc) and chiasmata—all occur in meiotically dividing cells. The majority of genes do not turn the meiotic process entirely off; they rather interfere with its distinct steps. These comparisons of meiotic mutants make it possible to distinguish between primary and secondary abnormalities caused by mutations in different genes. Other meiotic mutants can serve as points plotted on a genetic flowchart depicting the sequential switching on of meiotic genes. Chromosome behavior appears to be controlled at two levels. There seems to exist a group of genes controlling the behavior of all the chromosomes in the nucleus and another group that controls the behavior of single chromosomes.
172 citations
TL;DR: It is proposed that the number of elements in each family has been fixed by selection, and the size of each family of repeated sequences remains fairly constant in both strains.
Abstract: Most of the middle repetitive DNA of Drosophila melanogaster appears to be organized into families of 10-100 repeated elements that are found at scattered locations in the chromosome arms and occupy new chromosomal positions as populations of D. melanogaster diverge. These "nomadic" DNA segments can be identified by an analysis of cDm plasmids, hybrids of ColE1 and segments of randomly sheared D. melanogaster DNA. Eighty cDm plasmids were withdrawn, at random, from a library of approximately 17,000 cDm clones. Fifty-seven of these seem to contain either DNA that is not repeated in the D. melanogaster genome or DNA that has a low repetition frequency. The remaining 23 cDm plasmids contain repetitive sequences. Seventeen of these 23 plasmids contain repetitive sequences that are demonstrably scattered to many chromosomal sites that can be mapped in two D. melanogaster strains, g-1 and g-X11. The repeated elements hybridizing with each of the different Dm segments are at quite different chromosomal locations in these two strains. However, the size of each family of repeated sequences remains fairly constant in both strains. It is proposed that the number of elements in each family has been fixed by selection.
151 citations
TL;DR: The 24 human chromosome types of normal diploid fibroblast cell strain were classified into 15 groups by high-resolution flow cytometry on the basis of 33258 Hoechst fluorescence and the average purity for the 12 sorted fractions was 78%.
Abstract: The 24 human chromosome types of normal diploid fibroblast cell strain were classified into 15 groups by high-resolution flow cytometry on the basis of 33258 Hoechst fluorescence. Chromosomes associated with each group were flow sorted onto microscope slides and identified by quinacrine banding analysis. DNA cytophotometry of metaphase chromosomes from the same cell strain supported and extended this identification. Four of the groups purified were due to chromosomes of a single type--namely, chromosomes 5, 6, 13, and 17. Eight additional groups were also separated and found to contain the following chromosomes: 1 and 2; 3 and 4; 7, 8, and X; 9--12; 14 and 15; 16 and 18; 20 and Y; and 19, 21, and 22. The average purity for the 12 sorted fractions was 78%.
128 citations
TL;DR: Instability of the centromeric region of chromosome 1 and multibranched configurations formed by different numbers and combinations of arms of chromosomes 1, 9, and 16 were found in cultured lymphocytes of 12-year-old male with combined IgA and IgE deficiency.
Abstract: Instability of the centromeric region of chromosome 1 and multibranched configurations formed by different numbers and combinations of arms of chromosomes 1, 9, and 16 were found in cultured lymphocytes of 12-year-old male with combined IgA and IgE deficiency. No chromosome abnormalities were found in fibroblast cultures from the patient or in blood cultures from his parents. A possible effect on the frequency of the abnormalities of the almost continuous antibiotic treatment received by the patient was found both in vivo and in vitro, but no abnormalities were found in blood cultures from control subjects who received similar treatment. Interphase association of chromosomes 1, 9, and 16 and a high frequency of interchanges among the centromeric regions of these chromosomes due to the presence of a fragile site is assumed to be the cause of the abnormalities.
96 citations
TL;DR: The human genes for thymidine kinase, galactokinase and procollagen type I, located on chromosome 17, have been transferred to cultured mouse cells and the transferred genetic material is shown to exist independently in unstable cell lines, whereas in stable cell lines the transferred material has become associated with chromosomes of the recipient cell.
Abstract: The human genes for thymidine kinase, galactokinase and procollagen type I, located on chromosome 17, have been transferred to cultured mouse cells. In unstable cell lines the transferred genetic material is shown to exist independently, whereas in stable cell lines the transferred material has become associated with chromosomes of the recipient cell. The size of the transferred genetic material exceeds 1% of the human haploid genome in some of the transformed cell lines. In addition, the data indicate a gene order of: centromere–galactokinase–(thymidine kinase, procollagen type I), on the long arm of human chromosome 17.
92 citations
TL;DR: Eight X-linked recombination-defective meiotic mutants and 12 X- linked mutagen-sensitive mutants of Drosophila melanogaster have been examined cytologically in neuroblast metaphases for their effects on the frequencies and types of spontaneous chromosome aberrations.
Abstract: Eight X-linked recombination-defective meiotic mutants (representing five loci) and 12 X-linked mutagen-sensitive mutants (representing seven loci) of Drosophila melanogaster have been examined cytologically in neuroblast metaphases for their effects on the frequencies and types of spontaneous chromosome aberrations. Twelve mutants, representing five loci, significantly increase the frequency of chromosomal aberrations. The mutants at these five loci, however, differ markedly both in the types of aberrations produced and the localization of their effects along the chromosome. According to these criteria, the mutants can be assigned to four groups: (i) mutants producing almost exclusively chromatid breaks in both euchromatin and heterochromatin; (ii) mutants producing chromatid and isochromatid breaks in both euchromatin and heterochromatin; (iii) mutants producing chromatid mutants producing chromatid and isochromatid breaks clustered in the heterochromatin.
86 citations
TL;DR: Mouse-hamster somatic cell hybrids containing a variable number of mouse chromosomes have been used in experiments to determine which mouse chromosome carries the immunoglobulin kappa light chain genes, and it has been shown by nucleic acid hybridization that the kappa constant gene and the genes for at least one variable region subgroup are on mouse chromosome 6.
Abstract: Mouse-hamster somatic cell hybrids containing a variable number of mouse chromosomes have been used in experiments to determine which mouse chromosome carries the immunoglobulin kappa light chain genes. It has been shown by nucleic acid hybridization that the kappa constant gene and the genes for at least one variable region subgroup are on mouse chromosome 6. This somatic cell genetic mapping procedure appears to be general and can be applied to any expressed or silent gene for which an appropriate nucleic acid probe exists.
TL;DR: It is hypothesized that the distribution and characteristics of recurrent deviations, particularly structural ones, are “programmed” by genic changes related to cell differentiation.
TL;DR: This chapter provides information to the developmental aspects of chromosome control and banding methods advance knowledge of the chromosome, particularly with regard to the way in which it varies.
Abstract: Publisher Summary This chapter provides information to the developmental aspects of chromosome control. Chromosomes can provide important evidence of their own evolution and of that of the plants, which possess them. Chromosomes can be studied in several ways, many of which are complementary to each other. The study of the chromosome phenotype has been and will remain the way in which the chromosome is observed in action during mitosis and meiosis, demonstrating how it carries out its hereditary functions. Banding methods expose more linear differentiation at both divisions and so reveal more detail of the chromosome phenotype. DNA measurement expresses another aspect of it. Both techniques advance knowledge of the chromosome, particularly, with regard to the way in which it varies. Individual chromosomes, just as the DNA of which they are constructed, are capable of changing their linear arrangement without loss of function. They are generally constant in heredity but their inherent mutability produces a small but incessant level of structural change, which provides the variation necessary for chromosome evolution. Some types of chromosome reorganization result in numerical changes but errors of mitosis and meiosis produce larger differences in chromosome number often giving rise to cells, and subsequently individuals, with a doubled number. Alone or in combination these chromosomal and nuclear events are the prime sources of the wide karyotype variation.
TL;DR: Giemsa C-banded idiograms that allow the identification of all chromosomes have been prepared for Allium cepa, Ornithogalum virens, and Secale cereale to discuss the evolutionary conservation and function of repeated DNA sequences.
Abstract: Giemsa C-banded idiograms that allow the identification of all chromosomes have been prepared for Allium cepa, Ornithogalum virens, and Secale cereale. An analysis of A. cepa DNA has determined that: (1) It has the lowest GC content so far reported for an angiosperm (∼32%). (2) It appears to have no satellite DNA detectable by CsCl or Cs2SO4-Ag+ density gradient centrifugation. (3) Aside from fold back DNA and unreactable fragments, a C0t curve indicates that most of the DNA can be adequately described as two major middle repetitive components (Fractions I and II) and a single copy component (Fraction III). And (4) most of the repeated DNA sequences are involved in a “short period” interspersion pattern with single copy and other repetitive sequences. In situ hybridization of tritiated cRNAs to fold back, long repeated, and Fraction I DNA from A. cepa to squash preparations of chromosomes and nuclei from A. cepa, O. virens, and S. cereale root tips indicates: (1) Sequences complementary to fold back DNA are scattered throughout the genome of A. cepa except for telomeric heterochromatin and nucleolus organizers while they are not detectable in the genomes of O. virens or S. cereale. (2) Although long repeated sequences are scattered throughout the genome of A. cepa, they are concentrated to some extent in telomeric heterochromatin and nucleolus organizers (NOs). Sequences complementary to long repeats of A. cepa occur primarily in chromosome three of O. virens while these sequences are more common in the genome of more distantly related S. cereale. (3) Fraction I DNA is scattered throughout the genome of A. cepa while it is hardly detectable in the genomes of O. virens and S. cereale. These results are discussed in regard to the evolutionary conservation and function of repeated DNA sequences.
TL;DR: These experiments confirm the earlier assignment of the endogenous viral sequence related to Rous-associated virus-0 to a separate (and larger) chromosome than the cellular sequencerelated to the transforming gene of avian sarcoma virus (cellular sarc), although it now appears that cellular sarc is on a small macrochromosome, rather than on a micro Chromosome.
Abstract: Chicken metaphase chromosomes were partially purified by rate zonal centrifugation, and DNA was prepared from each of the fractions of the sucrose gradient. The DNA was digested with various restriction enzymes and subjected to electrophoresis in agarose gels. The DNA was transferred to nitrocellulose filters (as described by Southern), and the filters were hybridized with cDNA probes. Four globin genes alpha A, alpha D, beta, and rho or epsilon are located on at least two chromosomes, and three of the estrogen-inducible genes of the hen oviduct--ovalbumin, ovomucoid, and transferrin--are on three different chromosomes. These experiments also confirm our earlier assignment of the endogenous viral sequence related to Rous-associated virus-0 to a separate (and larger) chromosome than the cellular sequence related to the transforming gene of avian sarcoma virus (cellular sarc), although it now appears that cellular sarc is on a small macrochromosome, rather than on a microchromosome.
TL;DR: Using meiotic mapping techniques to locate the position of the repeating ribosomal DNA (rDNA) genes of the yeast Saccharomyces cerevisiae, it is found that the rDNA genes are located on the right arm of chromosome XII, approximately 45 map units centromere distal to the gene gal2.
Abstract: We have used meiotic mapping techniques to locate the position of the repeating ribosomal DNA (rDNA) genes of the yeast Saccharomyces cerevisiae. We found that the rDNA genes are located on the right arm of chromosome XII, approximately 45 map units centromere distal to the gene gal2. Together with mapping data from previous studies, this result suggests that the tandem array of rDNA genes contains at least two junctions with the non-rDNA of the yeast chromosome. In addition, we observed segregation patterns of the rDNA genes consistent with meiotic recombination within the rDNA gene tandem array in 3 of the 59 tetrads examined. Images
TL;DR: The genetic control of major wheat endosperm proteins by homoeologous group 1 chromosomes has been studied by two-dimensional polyacrylamide gel electrophoresis and six protein subunits have been shown to be controlled by chromosome 1C(u) of the related species, Aegilops umbellulata.
Abstract: The genetic control of major wheat endosperm proteins by homoeologous group 1 chromosomes has been studied by two-dimensional polyacrylamide gel electrophoresis. The control of at least 15 distinct protein subunits or groups of protein subunits has been allocated to chromosomes 1A, 1B and 1D of Chinese Spring wheat from the analysis of grains of aneuploid genotypes. In addition, six protein subunits have been shown to be controlled by chromosome 1Cu of the related species, Aegilops umbellulata, from studies of wheat lines carrying disomic substitutions of 1Cu chromosomes. On the basis of protein subunit patterns, chromosome 1Cu is more closely related to chromosome 1D of wheat than to chromosomes 1A or 1B.
TL;DR: Gene Sr21 for resistance to Puccinia graminis tritici in five hexaploid derivatives of the diploid Triticum monococcum was located in chromosome 2A and was placed 2·4±0·9 recombination units from the centromere in 2AL.
Abstract: Gene Sr21 for resistance to Puccinia graminis tritici in five hexaploid derivatives of the diploid Triticum monococcum was located in chromosome 2A. Since only one chromosome was involved in resistance, abnormal ratios found in some diploid wheat crosses and in one hexaploid derivative were attributed to differential transmission of gametes rather than to gene duplication in the diploid wheat sources. By using 2AS and an unknown telocentric presumed to be 2AL in telocentric mapping, Sr21 was placed 2·4±0·9 recombination units from the centromere in 2AL.
01 Jan 1979
TL;DR: DNA contents once more establish the close relationship of the S. nivalis subgroup with the taxa formerly classified under Chionodoxa, viz.
Abstract: The amounts of nuclear DNA and constitutive heterochromatin have been determined in 18 species of the Scilla bifolia group. and in the less closely related. S. messeniaca and S. siberica. Together with morphological criteria these data allow to reconstruct the pathways of chromosome evolution in the S. bifolia group at the diploid level with considerable accuracy. A progressive decrease of the DNA content by a factor of 0.5 occurred during the evolution from primitive yellow-seeded (S. kladnii: 1C = 8.6 pg) to advanced black-seeded species (e.g. S. luciliae: 1C = 4.3 pg). Grey- and brown-seeded species correspond to intermediary evolutionary stages and have intermediate DNA contents. 14 of 18 species have low amounts of heterochromatin (appr. 4%) irrespective of DNA content. However, two separate evolutionary side-branches are characterized by the accumulation of C-band material (3 yellow-seeded and 1 black-seeded species). The data suggest that an incipient DNA increase due to heterochromatin addition occurred in both instances. Further speciation in the yellow-seeded branch was accompanied by a decrease of total DNA despite of an increase in C-band content.—DNA contents once more establish the close relationship of the S. nivalis subgroup with the taxa formerly classified under Chionodoxa, viz. the S. luciliae subgroup.— The systematic position of S. messeniaca (x = 9) next to the S. bifolia group, previously suggested for reasons of morphology and chromosome number, is now supported by the DNA amount (1C = 10.7 pg). S. siberica (x = 6) as a remote relative contains considerably more DNA (1C = 31.7 pg).
TL;DR: Cutting-edge restriction endonuclease digestion studies revealed drastic differences in the organization of the repeats between macro- and micronucleus which may be interpreted as the results of chromosome fragmentation which occurs at every cluster of the repeat during macronuclear development.
Abstract: Synopsis.
The DNA of the macro- and the micronucleus of Tetrahymena thermophila has been compared by various biochemical methods. It became evident from their thermal denaturation temperatures and buoyant densities that the 2 DNAs were very similar in overall composition. Small differences were detected when the sequence complexities of these DNAs were compared by DNA renaturation studies. The studies suggested that ˜ 10% of the micronuclear genome was lost or underrepresented in the macronucleus. Comparison of individual gene levels revealed further differences. By using the technic of gene cloning a micronuclear sequence was isolated which hybridized only with micronuclear, but not with macronuclear DNA. These results indicated the occurrence of elimination or underreplication of this sequence in the macronucleus. Gene amplification was also shown to occur. In the micronucleus only a single copy of rDNA was found integrated into the chromosome. During macro-nuclear development, amplification was observed to occur, and the amount of rDNA to increase, until there were ˜ 200 copies per haploid genome in the mature macronucleus. all of them extrachromosomal and palindromic. The 3rd case of alteration involved a simple repeated sequence, (CCCCAA)n, present in the termini of rDNA and also in many other locations of the genome. Restriction endonuclease digestion studies revealed drastic differences in the organization of the repeats between macro-and micronucleus. These differences may be interpreted as the results of chromosome fragmentation which occurs at every cluster of the repeats during macronuclear development. The relationship between this event and gene amplification and elimination is discussed.
TL;DR: In this article, the authors examined viral and poly(rI):poly(rC) induction of interferon synthesis in several human, mouse and Chinese hamster cells lines, and in hybrids derived from the fusion of such cells.
TL;DR: This work describes how nucleic acid hybridisation and restriction endonuclease mapping of DNA can be combined to test for the presence of human structural gene sequences within hybrid cell DNA.
Abstract: Human–mouse somatic cell hybrids have proved invaluable in assigning human genes to their respective human chromosomes1. To date, the success of this approach has depended on identifying human proteins which are synthesised in hybrid cells containing a small number of human chromosomes. Consequently, chromosome assignment has been limited mainly to human proteins which are expressed in man–mouse somatic cell hybrids and for which a suitable assay, usually electrophoretic or immunological, exists to distinguish between the human and murine homologous proteins. This technique is therefore unsuitable for the assignment of those human genes which are expressed only in differentiated cells and not in hybrid cells. Here, we describe how nucleic acid hybridisation and restriction endonuclease mapping of DNA can be combined to test for the presence of human structural gene sequences within hybrid cell DNA. This method can be used to assign any purified human DNA sequence to a human chromosome, and does not require the DNA sequence to be expressed in man–mouse hybrid cells.
TL;DR: It is suggested that males are heteromorphic for the long homologue due to chromatin diminution, that occurs in the maturation division of mitotic parthenogenesis.
Abstract: Eggs obtained from feces of rabbits infected with Strongyloides papillosus were squashed and the karyotypes were determined. They contained cells with either two long and two medium sized chromosomes (2L2M), or one long, three medium and one short chromosome (L3MS). Two types of parasitic female gonad could be distinguished on the basis of oocyte chromosome morphology at prometaphase of the maturation division. All the oocytes in a gonad contained either two upaired long chromosomes and two unpaired medium sized chromosomes, or two unpaired medium sized chromosomes and two unpaired chromosomes segmented into beads in one region. At the maturation division in mitotic parthenogenesis the beads appear to be lost from one of the chromosomes. This generates a medium sized and a shorter chromosome, which together with the undiminished chromosomes make up the L3MS karyotype. Animals with beaded oocyte chromosomes lay eggs that develop into males. It is suggested that males are heteromorphic for the long homologue due to chromatin diminution, that occurs in the maturation division of mitotic parthenogenesis.
TL;DR: Zein, the storage protein accumulated in maize endosperm, is composed of several polypeptides which can be separated by isoelectric-focusing (IEF) analysis, and three bands were shown to be controlled by factors localised on the analysed chromosome segments.
Abstract: Zein, the storage protein accumulated in maize endosperm, is composed of several polypeptides which can be separated by isoelectric-focusing (IEF) analysis. Much IEF zein variability is found when analysing different inbred lines—the number of bands varies from 8 to 15 and can occupy about 27 positions—and F1 endosperms show an additive parental pattern. Chromosomal location of factors controlling the phenotypic expression of eight IEF bands was studied by means of translocations between A and B chromosomes and trisomic stocks, which allowed a large part of the genome to be explored. Three bands were shown to be controlled by factors localised on the analysed chromosome segments: one close to the R locus on chromosome 10, one on the short arm of chromosome 4 and one on a segment composed of portions from the short arm of chromosome 9 and the long arm of chromosome 4. The band controlled by the factor on chromosome 10 occupies the same IEF position as one which was found to be controlled by a factor on chromosome 7 near the opaque-2 locus. However, on the basis of SDS electrophoresis, these two polypeptides were found to have different molecular weights. The results obtained are discussed in relation to the molecular origin of zein heterogeneity.
TL;DR: The possible role of the partial deletion of the No. 2 chromosome was considered in relation to the development of mouse myeloid leukemias and various chromosomes had structural abnormalities.
Abstract: Chromosomes of mouse myelocytic leukemias that developed in 7 irradiated mice, 3 C3H/He males, 1 RFM female, and 3 RFM males were analyzed with chromosome-banding techniques. Chromosomes No. 2 were partially deleted in 6 of the 7 mice. Although the deleted No. 2 chromosomes varied in size in the 6 mice, one common characteristic was noted in all these deletions: A segment lying between a certain band in the region 2C and a band in the region 2E, including the whole region 2D, was missing. Another consistent abnormality was an addition or a loss of the Y-chromosomes in the fraction of cells in all 6 males. In addition to these consistent abnormalities, various chromosomes had structural abnormalities. The RFM female, which did not have the abnormal No. 2 chromosome, had abnormalities in chromosomes No. 3, 4, 11, 12 and 15 and in the X-chromosome. Of the 20 chromosome pairs, only such chromosomes as No. 1, 5, 8, 14, 17, and 19 and the Y-chromosome did not have the structural abnormalities. The possible role of the partial deletion of the No. 2 chromosome was considered in relation to the development of mouse myeloid leukemias.
TL;DR: Pachytene nuclei were studied in five tertiary trisomic male mice of Ts(113)70H and two ofTs(512)31H, with special attention given to the sex vesicles, and the chromatin structure of the extra chromosome as judged by a fine granular appearance resembled that of the sex chromosomes.
Abstract: Pachytene nuclei were studied in five tertiary trisomic male mice of Ts(113)70H and two of Ts(512)31H, with special attention given to the sex vesicles. Silver stained air dried cells analysed by light microscopy were used mainly, but in addition one sample of surface spread, ethanolic phosphotungstic acid stained nuclei was analysed by electron microscopy. With both techniques and both karyotypes, the extra chromosome (or the greater part of it) almost consistently aggregated with the sex chromosomes. Thereby, the chromatin structure of the extra chromosome as judged by a fine granular appearance resembled that of the sex chromosomes. The animals used ranged from almost azospermic to fertile oligospermic. This variation was not reflected in the position and morphology of the chromosomes 113 and 512. — Using the whole mount spreading EM technique within a Ts(113)70H tertiary trisomic, both 13;13;113 trivalents and 113 univalents were observed. The 13;13;113 trivalents showed a variety of morphologies, ranging from a situation showing classical partner exchange to complete synapsis between the two 13 homologues with the 113 telomeric region adhering. The latter configuration is thought not to lead to chiasma formation.
TL;DR: In this paper, the so-called controlling element (CE), which normally programs the curious behavior of the sex chromosome in this genus, has been localized in the short right arm of the polytene X in S coprophila.
Abstract: The so-called controlling element (CE), which normally programs the curious behavior of the sex chromosome in this genus, has been localized in the short right arm of the polytene X in S coprophila The localization was accomplished by use of five X-autosome translocations whose break points define three blocks of heterochromatin (“heterochromomeres”) extending from the X centromere to the very end (right) of the chromosome The behavior of the translocation chromosomes at the crucial second spermatocyte division was examined and the “precocious” chromosome identified in all five cases Then, knowing the heterochromomere make-up of each chromosome, the position of the CE could be mapped; it is located in heterochromomere H2, the same block of heterochromatin that contains 50% of the ribosomal RNA cistrons — The question of whether the CE can manipulate any centromere in the nucleus has been only partially answered It can manipulate translocation chromosomes which possess the centromere of the metacentric autosome (salivary chromosome IV) or that of the shorter rod (salivary chromosome II); but the longer rod (salivary chromosome III) whose proximal end, as seen in the polytene nucleus, is heavily laden with heterochromatin of its own, has not been brought under CE control — In one of the translocations, T23, the precocious chromosome is a very large metacentric chromosome which resembles the “peculiar” V-shaped X of S pauciseta This peculiarity is not observed in the J-shaped precocious chromosome of T29 These points are discussed
TL;DR: It was found in two separate series of human–mouse somatic cell hybrid cell lines and their diphtheria toxin-resistant subclones that human interferon production segregated from chromosome 5 and, furthermore, did not correlate with the presence of chromosomes 2 and 5 together.
Abstract: HUMAN fibroblast interferon is a single monomeric gly-coprotein1, and presumably a single structural gene codes for the human interferon polypeptide It was originally reported that chromosomes 2 and 5 were necessary together for human interferon production2 More recent evidence suggests that both chromosomes 2 and 5 carry separate human interferon genes3,4 However, we have found, in two separate series of human–mouse somatic cell hybrid cell lines and their diphtheria toxin-resistant subclones5,6, that human interferon production segregated from chromosome 5 and, furthermore, did not correlate with the presence of chromosomes 2 and 5 together7 Furthermore, using 29 hybrid clones (13 independent primary hybrids and 16 subclones) we could exclude chromosomes 1–8, 10–22 and X as candidates for the localisation of a single gene coding for human interferon on the basis of discordance of more than three clones for the segregation of human interferon production and the presence of a particular chromosome However, there was a good correlation between the production of human interferon and the presence of chromosome 9 Here we demonstrate this directly