Showing papers on "Ploidy published in 1982"
TL;DR: One hundred and six triploids were ascertained during a study of 1500 consecutive spontaneous abortions by comparing parental and foetal cytogenetic heteromorphisms and a histopathological examination of each triploid was done in a subsequent blind study.
Abstract: One hundred and six triploids were ascertained during a study of 1500 consecutive spontaneous abortions. The mechanism of origin of the additional haploid complement was investigated by comparing parental and foetal cytogenetic heteromorphisms and a histopathological examination of each triploid was done in a subsequent blind study. The mechanism of origin of the additional haploid complement was found to be highly correlated with the development of partial hydatidiform mole and with gestational age. All 51 paternally derived triploids in which a pathologic diagnosis could be made were partial moles, whereas only 3 of 15 maternally derived triploids on which a diagnosis could be made were molar. The mean gestational age of the paternally derived triploids was 122 days while that of the maternally derived triploids was only 74 days. It was suggested that the development of partial mole was primarily associated with the presence of two paternal haploid chromosome complements, the association with relatively long gestational ages being a secondary one consequent upon retention of the molar placentae for many weeks after foetal demise.
331 citations
TL;DR: The data strongly argue against somatic pairing as a regular event, and suggest a considerable variability of chromosome positions in different nuclei, however, present data do not exclude the possibility of certain non-random chromosomal arrangements in CHL-nuclei.
Abstract: Unsynchronized cells of an essentially diploid strain of female Chinese hamster cells derived from lung tissue (CHL) were laser-UV-microirradiated (λ=257 nm) in the nucleus either at its central part or at its periphery. After 7–9 h postincubation with 0.5 mM caffeine, chromosome preparations were made in situ. Twenty-one and 29 metaphase spreads, respectively, with partial chromosome shattering (PCS) obtained after micro-irradiation at these two nuclear sites, were Q-banded and analyzed in detail. A positive correlation was observed between the frequency of damage of chromosomes and both their DNA content and length at metaphase. No significant difference was observed between the frequencies of damage obtained for individual chromosomes at either site of microirradiation. The frequency of joint damage of homologous chromosomes was low as compared to nonhomologous ones. Considerable variation was noted in different cells in the combinations of jointly shattered chromosomes. Evidence which justifies an interpretation of these data in terms of an interphase arrangement of chromosome territories is discussed. Our data strongly argue against somatic pairing as a regular event, and suggest a considerable variability of chromosome positions in different nuclei. However, present data do not exclude the possibility of certain non-random chromosomal arrangements in CHL-nuclei. The interphase chromosome distribution revealed by these experiments is compared with centromere-centromere, centromere-center and angle analyses of metaphase spreads and the relationship between interphase and metaphase arrangements of chromosomes is discussed.
149 citations
TL;DR: The results demonstrate that gametophytic selection for low temperature tolerance of tomato pollen is determined, at least in part, by genes expressed in the haploid pollen.
Abstract: Pollen grains were harvested from an interspecific F1 hybrid between the cultivated tomato, Lycopersicon esculentum Mill., and its wild relative Lycopersicon hirsutum Humb. & Bonpl., a low temperature tolerant accession originating from an altitude of 3200 m in the Peruvian Andes. The two species differ for electrophoretically-detectable loci that mark six (possibly seven) of the 12 tomato chromosomes. Isozyme analysis of the BC1 populations derived from controlled pollinations at normal and low temperatures indicates a significant skewing of allelic frequencies favoring two independent chromosome segments of L. hirsutum at low temperatures. The results demonstrate that gametophytic selection for low temperature tolerance of tomato pollen is determined, at least in part, by genes expressed in the haploid pollen.
144 citations
TL;DR: The karyotypes of the bivalves Ostrea edulis, Crassostrea gigas, Mytilus galloprovincialis (2 n=28), and M. eduloides were obtained from mitotic metaphases of branchial tissue using a cellular suspension technique.
Abstract: The karyotypes of the bivalves Ostrea edulis (2 n=20), Crassostrea gigas (2 n=20), Mytilus galloprovincialis (2 n=28) and M. edulis (2 n=28) were obtained from mitotic metaphases of branchial tissue by means of a cellular suspension technique. The occurrence of metacentric, submetacentric and telocentric chromosomes in O. edulis as well as differences in size between Pair 1 and Pair 10 emphasize the cytological interest of this species compared to C. gigas which possesses only metacentric and submetacentric chromosomes. The variation in Pair 2, which is telocentric in M. galloprovincialis and metacencentric in M. edulis, has been observed for the first time and may support taxological separation of these two species. The karyotypes of the mesogastropods Rissoa ventricosa (2 n=32) and Littorina neritoides (2 n=34) were obtained from mitotic metaphases of gonadal tissue by the same technique. Sexual chromosomes were identified in the karyotypes of R. ventricosa. At the beginning of spermatogenesis, the gonad of L. neritoides shows both haploid and polyploid meiotic metaphases which correspond to typical (germinal cells) and atypical (nurse cells) forms, respectively.
121 citations
TL;DR: Progeny analysis of androgenetic plants from inbred rape-seed (Brassica napus) shows that selective growth of microspores can occur in cultured anthers and it is demonstrated that recessive mutations can be obtained in a homozygous state in doubled haploid regenerants from mutagenized haploid single cells.
Abstract: Progeny analysis of androgenetic plants from inbred rape-seed (Brassica napus) shows that selective growth of microspores can occur in cultured anthers. The property of privileged growth in culture seems to be linked to such characters as flowering time and seed glucosinolate content which can be analyzed in regenerated plants. This type of selection and the fact that more variability is visible in regenerants from different microspores than in the progeny of the highly inbred anther donor line, demonstrates the higher degree of homozygosity in the doubled amphihaploids of B. napus. Furthermore, it is shown that haploid genomes of rape may be mutable. Thus it is possible to obtain several different homozygous lines from a single microspore. A system of haploid embryoids arising from single cells of the primary microspore regenerant has also been used to produce experimentally induced mutants. It is demonstrated that recessive mutations can be obtained in a homozygous state in doubled haploid regenerants from mutagenized haploid single cells.
105 citations
TL;DR: A technique in which mouse eggs are stimulated to develop parthenogenetically following their brief incubation in 7% ethanol in PBS is described, and very high rates of activation were achieved, and a detailed analysis presented of the class ofparthenogenone which develops a single haploid pronucleus following second polar body extrusion.
Abstract: A technique in which mouse eggs are stimulated to develop parthenogenetically following their brief incubation in 7% ethanol in PBS is described. Very high rates of activation were achieved, and a detailed analysis presented of the class of parthenogenone which develops a single haploid pronucleus following second polar body extrusion. As preliminary studies on presumptive haploid morulae indicated that a proportion of the metaphase spreads examined had an aneuploid chromosome constitution, the incidence of aneuploidy at the first cleavage mitosis was investigated. In the control groups the level of aneuploidy was about 1%, whereas in the ethanol-treated series the incidence ranged from 13 . 6-18 . 8%. Additional pre-treatment of ethanol-activated oocytes in low osmolar medium raised the incidence of aneuploidy to 28 . 3%. Metaphase groups with 18, 19, 21 and 22 chromosomes present were observed in addition to groups with a normal complement of 20 chromosomes. The possible mode of action of ethanol in inducing parthenogenetic activation of mouse oocytes, and a high incidence of aneuploidy, is discussed in relation to previous knowledge of the action of this agent. Preliminary studies using G-banding indicate that the aneuploidy observed appears to arise as a result of non-disjunction which may involve any of the chromosomes of the complement.
100 citations
TL;DR: It is found that the diploid chromosomes 4 are indeed involved in the suppression of malignancy in all the tumours that are examined, which include a carcinoma, a melanomas, a sarcoma and a lymphoma, and in all crosses between these malignant tumour cells and diploids fibroblasts, there is selective pressure in vivo against the chromosomes 4 derived from the dibloid cell and in favour of the chromosome 4derived from the malignant cell.
Abstract: Previous experiments with crosses between malignant and diploid mouse cells had shown that the reappearance of malignancy in hybrids in which it was initially suppressed was associated in some cases with the elimination of the chromosomes 4 derived from the diploid parent cell. In others, however, this did not appear to be so. In the present study, we have re-examined the role of the diploid chromosomes 4 in the suppression of malignancy using natural polymorphisms of the centromeric heterochromatin to identify the parental origin of the chromosomes 4 in the hybrid cells. We now find that the diploid chromosomes 4 are indeed involved in the suppression of malignancy in all the tumours that we have examined, which include a carcinoma, a melanoma, a sarcoma and a lymphoma. In all crosses between these malignant tumour cells and diploid fibroblasts, there is selective pressure in vivo against the chromosomes 4 derived from the diploid cell and in favour of the chromosomes 4 derived from the malignant cell. This indicates that the chromosomes 4 in all these tumours are in some way functionally different from the chromosomes 4 of the diploid fibroblast. Reappearance of malignancy in hybrids in which it was initially suppressed may result from a reduction in the number of diploid chromosomes 4, an increase in the number of malignant chromosomes 4, or both. The gene on the diploid chromosome 4 responsible for the suppression of malignancy acts in a dose-dependent manner.
96 citations
TL;DR: Analysis of electrophoretic variants of a compensated locus revealed that all three alleles are active in trisomies, and it is speculated that there are similar homeostatic mechanisms that modulate gene expression both in euploid and aneuploid genomes.
Abstract: Drosophila melanogaster individuals trisomic for an entire chromosome arm can survive to late stages of pupal development. We have examined the levels of five enzymes whose structural genes are located on the left arm of chromosome 2 both in trisomy 2L and in diploid strains. In trisomies, three distally mapping loci showed compensated levels of expression close to that observed in the diploid strains. Analysis of electrophoretic variants of a compensated locus revealed that all three alleles are active in trisomies. The two proximally located loci displayed dose-dependent levels of expression. Therefore, at the level of the individual gene, autosomal compensation appears to be an all-or-none phenomenon. Furthermore, the compensatory response may be regionally distributed along the chromosome arm. The presence of both autosomal and sex-linked dosage compensation prompts us to speculate that there phenomenon are similar homeostatic mechanisms that modulate gene expression both in euploid and aneuploid genomes.
95 citations
TL;DR: The analysis of the rDNA region provided evidence for rapid “fixation” of new repeated sequences at two levels, namely, among the 130 bp repeated sequences of the spacer and at the level of the repeated arrays of the 9 kb rDNA units.
Abstract: The nature of genome change during polyploid evolution was studied by analysing selected species within the tribe Triticeae. The levels of genome changes examined included structural alterations (translocations, inversions), heterochromatinization, and nucleotide sequence change in the rDNA regions. These analyses provided data for evaluating models of genome evolution in polyploids in the genus Triticum, postulated on the basis of chromosome pairing at metaphase I in interspecies hybrids. The significance of structural chromosome alterations with respect to reduced MI chromosome pairing in interspecific hybrids was assayed by determining the incidence of heterozygosity for translocations and paracentric inversions in the A and B genomes of T. timopheevii ssp. araraticum (referred to as T. araraticum) represented by two lines, 1760 and 2541, and T. aestivum cv. Chinese Spring. Line 1760 differed from Chinese Spring by translocations in chromosomes 1A, 3A, 4A, 6A, 7A, 3B, 4B, 7B and possibly 2B. Line 2541 differed from Chinese Spring by translocations in chromosomes 3A, 6A, 6B and possibly 2B. Line 1760 also differed from Chinese Spring by paracentric inversions in arms 1AL and 4AL whereas line 2541 differed by inversions in 1BL and 4AL (not all chromosomes arms were assayed). The incidence of structural changes in the A and B genomes did not coincide with the more extensive differentiation of the B genomes relative to the A genomes as reflected by chromosome pairing studies. To assay changing degrees of heterochromatinization among species of the genus Triticum, all the diploid and polyploid species were C-banded. No general agreement was observed between the amount of heterochromatin and the ability of the respective chromosomes to pair with chromosomes of the ancestral species. Marked changes in the amount of heterochromatin were found to have occurred during the evolution of some of the polyploids. The analysis of the rDNA region provided evidence for rapid “fixation” of new repeated sequences at two levels, namely, among the 130 bp repeated sequences of the spacer and at the level of the repeated arrays of the 9 kb rDNA units. These occurred both within a given rDNA region and between rDNA regions on nonhomologous chromosomes. The levels of change in the rDNA regions provided good precedent for expecting extensive nucleotide sequence changes associated with differentiation of Triticum genomes and these processes are argued to be the principal cause of genome differentiation as revealed by chromosome pairing studies.
75 citations
TL;DR: Chromosome analysis of G- and C-banded preparations of tumor material from nine primary carcinomas of the cervix with modal chromosome numbers in the range 41-49 showed the nonrandom involvement of certain chromosomes in structural and numerical changes.
74 citations
TL;DR: The hypothesis that 2n pollen produced by plants homozygous recessive for ps have been involved in the origin of cultivated tetraploid potatoes suggests that the importance of meiotic mutants such as ps for the successful evolution of polysomic polyploids is emphasized.
Abstract: A high gene frequency for ps (parallel spindles) is expected in cultivated tetraploid potatoes, S. tuberosum Group Tuberosum, if 2n pollen produced by ancestral diploid plants which were psps was involved in the origin and evolution of the potato. Fifty-six North American cultivars (varieties and advanced selections) were pollinated by diploid clones, either W 5295.7 or W 5337.3 which are homozygous recessive for ps. The segregation ratios in regard to 2n pollen production in derived tetraploid progenies, from 4x×2x crosses, reveal the genotype of ps in the cultivars. Microsporogenesis of 2n pollen producing 4x progeny was observed to avoid an overestimation of the frequency of 2n pollen producing plants due to mechanisms other than parallel spindles. More than 50% of the 56 cultivars are simplex (Pspspsps), since in each of these cultivars about 50% of their progeny produced 2n pollen. The ps gene frequency in the 56 cultivars was estimated as high as 0.69. The high frequency of ps in the tetraploid cultivars clearly supports the hypothesis that 2n pollen produced by plants homozygous recessive for ps have been involved in the origin of cultivated tetraploid potatoes, since a higher frequency of ps in the tetraploid than in the ancestral diploid population can be expected from sexual polyploidization but not from somatic doubling. The importance of meiotic mutants such as ps for the successful evolution of polysomic polyploids is emphasized.
TL;DR: It is concluded that the chromosome 21 gene product determined by IFRC and recognized by antibodies which block interferon action is truly a specific cell surface receptor for human interferons-α.
TL;DR: The dimensions of nucleus-associated organelles (equivalent to spindle pole bodies) in these strains increased as a function of ploidy number.
Abstract: Determination of ploidy was performed on isolates of Candida albicans from clinical sources by measuring nuclear DNA content with fluorescent microscope photometry. By this criterion and UV irradiation survival experiments, haploid, diploid, and tetraploid strains were identified in this organism. The dimensions of nucleus-associated organelles (equivalent to spindle pole bodies) in these strains increased as a function of ploidy number.
TL;DR: The data are consistent with the assumption that HML, MAT andHMR of the S. carlsbergensis chromosome are organized as in S. cerevisiae, and segments X and Z1, which are involved in mating type interconversion, were closely homologous to their S. Cerevisiae counterparts, whereas Y α as well as sequences outside theHML andMAT cassettes were substantially different.
Abstract: Chromosome III in a haploid Saccharomyces cerevisiae strain has been previously substituted for by its homeologue from S. carlsbergensis. With this chromosome substitution line the two homeologous chromosomes were shown to undergo crossing over only in a limited region, and to differ in nucleotide sequence at theHIS4 locus. In the present study the S. carlsbergensis chromosome III was compared to its S. cerevisiae homeologue at several additional loci. Cloned DNA from the S. cerevisiae lociHML, HIS4, LEU2, MAT andSUP-RL1 was used as hybridization probes in the analysis of nucleotide sequence homology at these loci andHMR. Virtually no differences were detected atSUP-RL1 andHMR, located in the region where the two chromosomes recombine, whereas considerable differences were found in the non-recombining part. The data are consistent with the assumption thatHML, MAT andHMR of the S. carlsbergensis chromosome are organized as in S. cerevisiae Segments X and Z1, which are involved in mating type interconversion, were closely homologous to their S. cerevisiae counterparts, whereas Y α as well as sequences outside theHML andMAT cassettes were substantially different.
TL;DR: The chromosomal locations of the 18S + 28S and 5S ribosomal RNA genes have been analyzed by in situ hybridization in ten anuran species of different taxonomic positions and microchromosomes and small chromosomes in primitive karyotypes have been found to carry 5S rDNA sequences.
Abstract: The chromosomal locations of the 18S + 28S and 5S ribosomal RNA genes have been analyzed by in situ hybridization in ten anuran species of different taxonomic positions. The chosen species belong to both primitive and evolved families of the present day Anura. Each examined species has 18S + 28S rRNA genes clustered in one locus per haploid chromosome set: this locus is placed either in an intercalary position or proximal to the centromere, or close to the telomere. The 5S rRNA genes are arranged in clusters which vary in number from one to six per haploid set. The 5S rDNA sites are found in intercalary positions, at the telomeres, and at, or close to, the centromeres. Microchromosomes and small chromosomes in primitive karyotypes have been found to carry 5S rDNA sequences. The results are discussed in relation to ideas on the karyological evolution of Amphibia.
TL;DR: The karyotypes of three human hepatoma cell lines Hep G2, Hep 3B and PLC/PRF/5 were investigated by G‐ and C‐banding techniques and certain markers were found that remained stable throughout passage of these cultures.
Abstract: The karyotypes of three human hepatoma cell lines Hep G2, Hep 3B and PLC/PRF/5 were investigated by G- and C-banding techniques. In addition to ploidy changes, typical for most carcinoma cell lines, certain markers were found that remained stable throughout passage of these cultures. Chromosome I is involved in multiple translocations, resulting in at least three copies of the chromosome I heterochromatin region in each cell line. Inversion in the 9qh region is also seen. In addition, each of the cell lines consistently contains trisomy of 17q. The rearrangements of chromosome I are most striking in the Hep 3B and PLC/PRF/5 cell lines, which are derived from human hepatocellular carcinomas and contain integrated copies of the hepatitis B viral genome. These two cell lines are characterized by the presence of at least five copies of the I (p13 leads to q21) region that result from multiple deletions and/or translocations; by consistent trisomy and polymorphism of the 9qh region; and by trisomy of chromosome 10 (also involved in rearrangements). The Hep G2 and Hep 3B cell lines behave functionally as highly differentiated liver parenchymal cells and are karyologically distinguishable from PLC/PRF/5 both by the presence of trisomy of 6 (pter leads to q14) and by the finding that one of the homologues of chromosome 15 is 15q+.
TL;DR: An investigation of abnormal events in chromosome number that occurred during meiosis and after treatment with MMS, Benomyl and Amphotericin B suggests that this assay system is suitable for screening environmental mutagens for their effects on meiotic segregation.
Abstract: Abnormalities in chromosome number that occurred during meiosis were evaluated with a specially-constructed diploid strain of Saccharomyces cerevisiae. The strain is heterozygous for six markers of the right arm of chromosome V and heterozygous for cyh2 (resistance to cycloheximide) on chromosome VII.—Selection of meiotic spores on a medium containing cycloheximide and required nutrilites—except those for the markers of the right arm of chromosome V—allows the growth of aberrant clones belonging only to two classes: a) diploid clones, caused by failure of the second meiotic division, with a frequency of 0.54 x 10-4 per viable spore; and b) diplo V, aneuploids derived from nondisjunctions in meiosis I or meiosis II, with a total spontaneous frequency of 0.95 x 10-4 per viable spore. About two-thirds of the aneuploids originated during meiosis I, the rest during meiosis II. An investigation of these events in control meioses and after treatment with MMS, Benomyl and Amphotericin B suggests that this assay system is suitable for screening environmental mutagens for their effects on meiotic segregation.
TL;DR: Analysis of chromosome pairing in microspore-derived haploids of broccoli, Brassica oleracea L. Bravo and Green Mountain, revealed a maximum chromosome pairing at MI of 2n = 18 cvs.
Abstract: Analysis of chromosome pairing in microspore-derived haploids of broccoli, Brassica oleracea L. var. italica (2n = 18) cvs. Bravo and Green Mountain, revealed a maximum chromosome pairing at MI of 4 I + 1 II + 1 III. These data disagree with the hypothesis that diploid B. oleracea is tetrasomic for three linkage groups but indicate that it could be tetrasomic for one and hexasomic for another. It is suggested that the aneuploid series in Brassica could also be derived from a combination of modified tertiary and compensating trisomics.
TL;DR: The results further localize the human PFKMlocus to region cen→q32 of chromosome 1, which is related to muscle-type, liver-type and platelet-type subunits of PFK.
Abstract: Human phosphofructokinase (PFK; EC 2.7.1.11) is under the control of three structural loci which encode muscle-type (M), live-type (L), and platelet-type (P) subunits; human diploid fibroblasts and leukocytes express all three loci. In order to assign human PFKM locus to a specific chromosome we have analyzed human x Chinese hamster somatic cell hybrids for the expression of human M subunits, using an anti-human M subunit-specific mouse monoclonal antibody. In 18 of 19 hybrids studied, the expression of the PFKM locus segregated concordantly with the presence of chromosome 1 (discordance rate 0.05) as indicated by chromosome and isozyme marker analysis. The discordance rates for all the other chromosomes were 0.32 or greater, indicating that the PFKM locus is on chromosome 1. For the regional mapping of PFKM, eight hybrids were studied that contained one of five distinct regions of chromosome 1. These results further localize the human PFKM locus to region cen leads to q32 chromosome 1.
TL;DR: Correlations between the expression of an unmapped gene and that of a previously mapped recessive marker indicated chromosomal linkage, and one previously unm mapped gene, nib1, was mapped.
Abstract: Mitotic chromosome loss induced by methyl benzimidazole-2-yl-carbamate has been utilized as a rapid and simple method for assigning genes to individual chromosomes in Saccharomyces cerevisiae. This technique relied on the segregation of heterozygous markers in a diploid strain after methyl benzimidazole-2-yl-carbamate treatment due to loss of whole chromosomes. Correlations between the expression of an unmapped gene and that of a previously mapped recessive marker indicated chromosomal linkage. Depending on whether the unmapped gene and the marker were located in coupling or in repulsion, either positive or negative correlations were seen. The chromosomal location of several previously mapped genes were confirmed as a test of the method, and one previously unmapped gene, nib1, was mapped.
TL;DR: It was concluded that increased cell volume rather than increased cell number per leaf is responsible for the increase in leaf size with ploidy.
Abstract: Photosynthetically-active protoplasts isolated from isogenic sets of diploid-tetraploid and tetraploid-octoploid alfalfa (Medicago sativa L.) leaves were used to investigate the consequences of polyploidization on several aspects related to photosynthesis at the cellular level. Protoplasts from the tetraploid population contained twice the amount of DNA, ribulose-1,5-bisphosphate carboxylase (RuBPCase), chlorophyll (Chl), and chloroplasts per cell compared to protoplasts from the diploid population. Although protoplasts from the octoploid population contained nearly twice the number of chloroplasts and amount of Chl per cell as tetraploid protoplasts, the amount of DNA and RuBPCase per octoploid cell was only 50% higher than in protoplasts from the tetraploid population. The rate of CO(2)-dependent O(2) evolution in protoplasts nearly doubled with an increase in ploidy from the diploid to tetraploid level, but increased only 67% with an increase in ploidy from the tetraploid to octoploid level. Whereas leaves and protoplasts had similar increases in RuBPCase, DNA, and Chl with increase in ploidy level, it was concluded that increased cell volume rather than increased cell number per leaf is responsible for the increase in leaf size with ploidy.
TL;DR: It is concluded that the bias in the frequency of progeny types towards diploidy or tetraploids, depending on the ploidy level of the plant which is crossed with the triploid, is caused by inter-embryo competition.
Abstract: In reciprocal crosses between diploid and triploid Aloineae the progeny are largely diploid or diploid plus one or two chromosomes, but in reciprocal crosses between triploids and tetraploids they are tetraploid or nearly so. Thus the triploids contribute circa haploid gametes to the progeny when crossed with diploids but circa diploid gametes when crossed with tetraploids. These results are compared with those of a number of earlier workers. It is concluded that the bias in the frequency of progeny types towards diploidy or tetraploidy, depending on the ploidy level of the plant which is crossed with the triploid, is caused by inter-embryo competition. Those embryos with an endosperm/embryo factor of 1.5, the value found in normal diploid/diploid crosses having triploid endosperms, are selected in preference to those with factors higher or lower than 1.5. Inter-gamete competition also occurs among the euploid and aneuploid gametes produced by the triploids. This is more pronounced on the male side, because the degree of survival of aneuploid pollen from the triploids into the next generation is much lower than that of aneuploid egg nuclei. Non-reduction in the triploids gives rise to occasional pentaploid progeny in crosses with tetraploids, but it is more probable that in diploid/triploid crosses tetraploid progeny are the products of non-reduction in the diploid.
TL;DR: Four cell lines derived from Nicotiana tissue with 2n=24, 48, or 72 were established and retain stable chromosome number and could be regenerated to recover plants that retained the somatic chromosome number during culture.
Abstract: Cell suspension cultures of Nicotiana were initiated using conditions designed to selectively favor stable chromosome number. These conditions included use of leaf explants to initiate cultures, growth of cells in culture medium containing 2,4-D, and transfer of cells with short subculture intervals. Four cell lines derived from Nicotiana tissue with 2n=24, 48, or 72 were established and retain stable chromosome number. Each line could be regenerated to recover plants that retained the somatic chromosome number during culture. Establishment of haploid and diploid cell lines with stable chromosome number is important for mutant isolation and protoplast fusion.
TL;DR: The somatic karyotype of pearl millet Pennisetum americanum (L.) Leeke has been studied in several cultivars, but few cytological markers have been discovered which could help in the easy identification of the chromosomes.
Abstract: The somatic karyotype of pearl millet Pennisetum americanum (L.) Leeke. (2n = 14) has been studied in several cultivars, but few cytological markers have been discovered which could help in the easy identification of the chromosomes. Analysis of pachytene bivalents permits such identification but is feasible only in a few cultivars. Recently, several lines having telocentric chromosomes have been produced and classified but their potentialities as cytogenetic tools have yet to be explored. Some African populations of pearl millet carry B-chromosomes in their karyotype. Cytogenetics of B-chromosomes has been reported in great detail. Bs undergo spontaneous changes to produce deficient- and iso-chromosomes. The main effect of B-chromosomes is on chiasma frequency which is exerted by the relative amounts of chiasma promoting euchromatin and the chiasma depressing heterochromatin in the Bs. Haploid plants occur occasionally and sometimes show a low degree of seed set, offering a possibility of establishing homozygous inbred lines. Cytogenetics of several spontaneous and induced autotetraploids have been reported. In general quadrivalent formation between the seven sets of four homologues was random. Seed set of the autotetraploids could be improved by selection; improved seed fertility was found to be associated with increased chiasma frequency, increased quadrivalent frequency and regular distribution of chromosomes at anaphase I. Genes controlling morphological characters of plant phenotype segregate independent of those controlling fertility and in pearl millet polyploidy per se is not limiting to plant vigour. Primary trisomics represent the best studied among the aneuploids of pearl millet. All the seven primary trisomics have been identified and described. Some were used in assigning genes to specific chromosomes but in general trisomies have poor vigour and fertility, and show low frequency of transmission. Apart from B-chromosomes, cytogenetics of interchanges has been the best studied aspect of pearl millet. The frequency of co-orientation of an interchange complex at metaphase I, which determines the fertility or sterility of the interchange heterozygote, is influenced by the genetic background and thus is theoretically amenable for selection leading to improved fertility of the heterozygote. Interchange tester-stocks have been assembled which can be used to identify the chromosomes involved in any newly obtained interchange. A complex interchange line involving all the chromosomes of the complement has also been produced, but the ring-of-fourteen produces total male and female sterility.
01 Jan 1982
TL;DR: Most plants were highly sterile because of breeding barriers, which were similar to those in the original intergeneric crosses, and the increase in fertility and chromosomal stability were studied in the first three generations of the populations.
Abstract: About 250 intergeneric hybrids with the genome constitution AR, AARR or ARR were obtained from over 15 000 crosses between Brassica campestris (AA or AAAA, female parent) and Raphanus sativus (RR or RRRR). The poor crossability was shown to be a consequence of various breeding barriers. The diploid and tetraploid hybrids were studied in form, fertility, chromosome association at meiosis and crossability both among the hybrids and in crosses with the parental species and Brassica napus . x Brassicoraphanus (AARR) was backcrossed twice with B . campestris (AA), and was also crossed and backcrossed with B . napus (AACC). Form and chromosome association at meiosis in AAR and AACR hybrids were studied. Two populations of X Brassicoraphanus (AARR) were propagated and studied in more detail, partly for possible suitability as a new crop. Most plants were highly sterile because of breeding barriers, which were similar to those in the original intergeneric crosses. The increase in fertility and chromosomal stability were studied in the first three generations of the populations.
TL;DR: There were differences both in the amount and distribution of heterochromatin and also translocation differences between the species, and the relationship between the genomes of T. timopheevi and T. araraticum was assessed.
Abstract: The chromosomes of the tetraploid wheats Triticum timopheevi (Genome AAGG) and T. araraticum (Genome AAGG) were C-banded at mitosis. The identity of the banded and unbanded chromosomes was then established by firstly making comparisons with the hexaploid species T. zhukovskyi which has the genome formula AAAAGG. Secondly, the meiotic pairing in F1 hybrids between T. timopheevi and diploid wheats was examined by means of C-banding. The results showed that the banded chromosomes belonged to the G genome, while the unbanded chromosomes belonged to the A genome. Only one of the two pairs of satellited chromosomes had strong heterochromatic bands. The relationship between the genomes of T. timopheevi and T. dicoccum (Genome AABB) was then assessed at meiosis in hybrids between these species, using the techniques of C-banding and in situ hybridisation of a cloned ribosomal RNA gene probe. It was concluded that there were differences both in the amount and distribution of heterochromatin and also translocation differences between the species.
TL;DR: A comparison of the isolectin pattern in these wheat species of increasing ploidy level made it possible to determine unequivocally the genome by which the individual lectin subunits in polyploid species are coded for.
Abstract: Wheat (Triticum aestivum) germ agglutinin represents a complex mixture of multiple isolectin forms. Upon ion exchange chromatography at pH 3.8, three isolectins can be separated, each of which is composed of two identical subunits. At pH 5.0, however, three additional isolectins can be distinguished, which are built up of two different subunits (heteromeric lectins). Evidence is presented that these heterodimers are normal constituents of the wheat embryo cells. Analyses of the isolectin patterns in extracts from Triticum monococcum, Triticum turgidum dicoccum and Triticum aestivum, provide evidence that each genome, either in simple or complex (polyploid) genomes, directs the synthesis of a single lectin subunit species. In addition, a comparison of the isolectin pattern in these wheat species of increasing ploidy level, made it possible to determine unequivocally the genome by which the individual lectin subunits in polyploid species are coded for. The possible use of lectins in studies on the origin of individual genoms in polyploid species is discussed.
TL;DR: It is concluded that the long arm of human chromosome 11 carries one or more genes coding for host functions necessary for the production of progeny HSV-1 DNA.
Abstract: Somatic cell hybrids between Chinese hamster (CH) lung cells (V79/380-6), nonpermissive for productive infection by herpes simplex type 1 (HSV-1), and permissive human diploid cells support productive HSV-1 infection as long as they retain human chromosome 11 Human chromosome 3 has been reported to complement nonpermissivity in (CH) Don cells (1) Intraspecies hybrids between Don/a3 and V79/380-6 cells, however, did not support HSV-1 replication, indicating lack of complementation The block in both nonpermissive CH cell lines was determined to involve a step beyond replication of the parental viral DNA In cell hybrids between nonpermissive Don/a23 cells and human fibroblasts containing a t(11;15) (p11;p12) translocation, HSV-1 production was dependent solely on the presence of either human chromosome 11 or the der(11) (p11→qter) translocation product containing the long arm of chromosome 11 Chromosome 3 was excluded by a discordancy rate of 59% We conclude that the long arm of human chromosome 11 carries one or more genes coding for host functions necessary for the production of progeny HSV-1 DNA
TL;DR: It was concluded that diploid-like meiosis in these species is due to genetic regulation.
Abstract: Polyploid species of Triticum sensu lato were crossed with Triticum aestivum L. em. Thell. cv. Chinese Spring monotelodisomics or ditelosomics that were monosomic for chromosome 5B. Progeny from these crosses were either euploid, nullisomic for 5B, monotelosomic for a given Chinese Spring chromosome, or nullisomic for 5B and monotelosomic simultaneously. The Chinese Spring telosome in the hybrids permitted the evaluation of autosyndesis of chromosomes of the tested species. In addition, several Chinese Spring eu- and aneuhaploids were produced. Genotypes of T. cylindricum Ces., T. juvenale Thell., T. triunciale (L.) Raspail, T. ovatum (L.) Raspail, T. columnare (Zhuk.) Morris et Sears, T. triaristatum (Willd.) Godr. et Gren., and T. rectum (Zhuk.) comb. nov. were all shown to have suppressive effects on heterogenetic pairing in hybrids lacking 5B or 3AS, whereas T. kotschyi (Boiss.) Bowden had no effect. It was concluded that diploid-like meiosis in these species is due to genetic regulation. A number of ...
TL;DR: The results of the present study indicate that cytophotometric DNA analysis, as an adjunct to conventional histologic evaluation, offers an objective means of differentiating between classical and paraosteal osteosarcomas.
Abstract: The cellular DNA content was determined in a consecutive series of 26 classical and two paraosteal osteosarcomas by means of single cell cytophotometry. All classical osteosarcomas regardless of histologic type (osteo-, chondro-, fibroblastic) or grade were found to be hyperploid (abnormally increased DNA content) while both paraosteal osteosarcomas proved to be diploid (normal DNA content). Closer analysis of the DNA distribution curves showed that the majority of the classical osteosarcomas exhibited a triploid modal DNA value and more than 90% hyperploid cells. Cytochemical characterization of osteosarcomas may be of prognostic significance in reflecting the degree of malignancy. The results of the present study indicate that cytophotometric DNA analysis, as an adjunct to conventional histologic evaluation, offers an objective means of differentiating between classical and paraosteal osteosarcomas.