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PubMedDate not supplied

Mixed gonadal dysgenesis: case reports and a review of 65 Japanese cases.

Four cases of mixed gonadal dysgenesis encountered in our institute are described here, and 65 cases of mixed gonadal dysgenesis in the Japanese literature, including our cases, are reviewed. Of the four cases reported here, three had a chromosomal structure of 46,XY and one of 45,XO/46,XYq-. A chromosomal structure of 45,XO/46,XY accounts for 35% of all cases of mixed gonadal dysgenesis reported in the Japanese literature, 46,XY for 31%, and other types for 24%. Two of our cases (50%) also had a gonadal tumor. The overall incidence of gonadal tumor occurring after onset of puberty and reported in the Japanese literature is 17%.

Adolescent↗
PubMed2000

Assessment of in vivo chromosomal aberrations--potency of zinc mercapto benzo thiazole.

Chromosomal aberrations are microscopically visible changes in the chromosome structure. The double-stranded breaks are the ultimate DNA lesions for chromosomal aberrations. The purpose of the present study was to evaluate the induction of chromosomal aberrations by the rubber accelerator zinc mercapto benzo thiazole (ZMBT). The experiment was designed with five groups, each composed of four Swiss albino mice. The first three groups received ZMBT at 1920, 960, and 480 microg/20 g animal. The remaining two groups were the vehicle (cotton seed oil) and positive (methyl methane sulphonate) controls. Animals were given a single dose of test and control samples by IP injection. Colchicine (20 microg/animal) was administered 90 minutes before sacrificing the animals. All the animals were sacrificed at the end of 36 h by cervical dislocation. Bone marrow preparations were made, stained with Giemsa stain, and examined for chromosomal abnormalities. The results indicated a lack of incidence of chromosomal abnormalities in the test and control groups. However, significant chromosomal abnormalities such as gaps, breaks, and translocations were observed in the positive control group. Hence, the study concluded that ZMBT at different concentrations fails to induce structural chromosomal aberrations in bone marrow cells.

Animals↗
PubMed1999

Human placental Na+-dependent multivitamin transporter. Cloning, functional expression, gene structure, and chromosomal localization.

We have cloned the human Na+-dependent multivitamin transporter (SMVT), which transports the water-soluble vitamins pantothenate, biotin, and lipoate, from a placental choriocarcinoma cell line (JAR). The cDNA codes for a protein of 635 amino acids with 12 transmembrane domains and 4 putative sites for N-linked glycosylation. The human SMVT exhibits a high degree of homology (84% identity and 89% similarity) to the rat counterpart. When expressed in HRPE cells, the cDNA-induced transport process is obligatorily dependent on Na+ and accepts pantothenate, biotin, and lipoate as substrates. The relationship between the cDNA-specific uptake rate of pantothenate or biotin and Na+ concentration is sigmoidal with a Na+:vitamin stoichiometry of 2:1. The human SMVT, when expressed in Xenopus laevis oocytes, induces inward currents in the presence of pantothenate, biotin, and lipoate in a Na+-, concentration-, and potential-dependent manner. We also report here on the structural organization and chromosomal localization of the human SMVT gene. The SMVT gene is approximately 14 kilobase pairs in length and consists of 17 exons. The SMVT gene is located on chromosome 2p23 as evidenced by somatic cell hybrid analysis and fluorescence in situ hybridization.

Amino Acid Sequence↗
PubMed2005

Decoding the nucleoid organisation of Bacillus subtilis and Escherichia coli through gene expression data.

BACKGROUND: Although the organisation of the bacterial chromosome is an area of active research, little is known yet on that subject. The difficulty lies in the fact that the system is dynamic and difficult to observe directly. The advent of massive hybridisation techniques opens the way to further studies of the chromosomal structure because the genes that are co-expressed, as identified by microarray experiments, probably share some spatial relationship. The use of several independent sets of gene expression data should make it possible to obtain an exhaustive view of the genes co-expression and thus a more accurate image of the structure of the chromosome. RESULTS: For both Bacillus subtilis and Escherichia coli the co-expression of genes varies as a function of the distance between the genes along the chromosome. The long-range correlations are surprising: the changes in the level of expression of any gene are correlated (positively or negatively) to the changes in the expression level of other genes located at well-defined long-range distances. This property is true for all the genes, regardless of their localisation on the chromosome. We also found short-range correlations, which suggest that the location of these co-expressed genes corresponds to DNA turns on the nucleoid surface (14-16 genes). CONCLUSION: The long-range correlations do not correspond to the domains so far identified in the nucleoid. We explain our results by a model of the nucleoid solenoid structure based on two types of spirals (short and long). The long spirals are uncoiled expressed DNA while the short ones correspond to coiled unexpressed DNA.

Bacillus subtilis↗
PubMed1989

Chromosome studies in thyroid neoplasia.

Cytogenetic studies in thyroid neoplasia were performed by G-banding of chromosome preparations obtained from the in vitro cultures of nine adenomas, one follicular carcinoma, five papillary carcinomas, and two medullary carcinomas. Complex structural chromosome aberrations were found in one adenoma. Two more adenomas, both composed of Hürthle cells, showed multiple numerical chromosome deviations with trisomy 4 and tetrasomy 7 in common. Six metastasizing carcinomas were characterized by normal stemlines, which indicates that malignancy in thyroid neoplasia cannot be excluded by cytogenetic techniques used currently. Comparisons between cytogenetic findings and cytophotometric DNA measurements in the material studied illustrate that euploid tumors represent a heterogenous group including cases with various gross structural chromosome aberrations of yet unknown clinical significance. Further studies of additional material with long-term follow-up are called for by our findings of structural and numerical chromosome aberrations in follicular neoplasms that are benign according to histologic criteria.

Adenoma↗
PubMed1987

[G-banded chromosome analysis of bone marrow and peripheral blood cells from small cell lung cancer (SCLC) patients].

Detailed G-banded chromosome analysis was carried out on the bone marrow and/or PHA-stimulated peripheral blood cells from 17 SCLC patients (14 males and 3 females), who were diagnosed cytologically or pathologically or both. Twelve of them had no prior treatment and 16 had a heavy smoking history. High chromosome aberration rates were found in the bone marrow (31% for average structural aberration rate and 63% for numerical aberration rate) and peripheral blood cells (37% for average structural aberration rate and 49% for numerical aberration rate). The smoking index, as a whole, was positively correlated to the structural chromosome aberration rate, indicating that smoking is one of the most important environmental factors in causing chromosome aberrations. But some patients gave a high aberration rate dis-proportional to their smoking index, suggesting that genetically determined susceptibility to smoking or even other factors also play an important role. The structural chromosome aberrations in the bone marrow and peripheral blood cells were mainly clustered on chromosome 3 and chromosomes 1, 9 and 11, respectively. The aberration types were manifold and complicated. No consistent or specific aberration as del 3p14-23 for SCLC was found in this study.

Bone Marrow↗
PubMed2001

Gene structure and chromosomal location of a human bHLH transcriptional factor DEC1 x Stra13 x SHARP-2/BHLHB2.

DEC1/BHLHB2 is a novel cAMP-inducible basic helix-loop-helix (bHLH) transcriptional factor isolated from human chondrocyte cultures by the subtraction method [Shen et al. (1997) Biochem. Biophys. Res. Commun. 236, 294--298]. DEC1 seems to be involved in controlling the proliferation/differentiation of some cell lineages. We determined the structure of the human DEC1 gene and its chromosomal locus. Phylogenetic analysis and comparison of the gene structure showed that the DEC1 protein is a member of a new subgroup of the proline bHLH protein family that diverged earlier than other proline bHLH proteins including HES, hairy and E(spl). The human DEC1 gene spans approximately 5.7 kb and contains 5 exons. The putative promoter region contains multiple GC boxes but no TATA box. A primer extension study showed multiple transcriptional initiation sites. In the 5'-flanking region of the DEC1 gene, several transcriptional factor binding sites, including a cAMP-responsive element (CRE), were found using the transcription factor database. The DEC1 gene locates at Chromosome 3p25.3--26 by the FISH method. This is the first study to determine the genomic structure of the DEC1 gene subgroup.

Amino Acid Sequence↗
PubMed1984

Structure and chromosomal arrangement of leghemoglobin genes in kidney bean suggest divergence in soybean leghemoglobin gene loci following tetraploidization.

We have determined the structure of one of the leghemoglobin (Lb) genes of Phaseolus vulgaris (kidney bean) and deduced the chromosomal arrangement of leghemoglobin genes by genomic hybridizations with Lb and two other sequences, each specific to the 5' or 3' region of the soybean leghemoglobin loci. By comparing this organization with two other species of legumes, Glycine max (soybean) and G. soja (wild soybean), a phylogeny of leghemoglobin gene loci was traced. The intragenic structure of the kidney bean leghemoglobin gene shows the same intron/exon arrangement as that of soybean leghemoglobin genes and extensive sequence homologies in both coding as well as 5' and 3' non-coding regions. The presence in the kidney bean genome of four leghemoglobin genes suggests that tandem duplications of a single primordial plant globin gene had occurred to generate four leghemoglobin genes in an ;Lb-locus' before Glycine and Phaseolus species diverged. Chromosome duplication by tetraploidization in Glycine generated two loci containing four genes each. A large deletion in one of the two four-gene loci in soybean resulted in the generation of the Lbc(2) locus containing two leghemoglobin genes, one functional and another pseudo (LbPsi(2)). This pseudogene, unlike that present on the main locus, is represented by only two and a half exons and appears to be truncated. The two other truncated genes (LbT(1) and LbT(2)) were probably generated similarly in the genome of Glycine spp. following tetraploidization before the divergence of G. max and G. soja.

Journal Article↗
PubMed1999

Molecular structure and chromosomal localization of major repetitive DNA families in the chickpea (Cicer arietinum L.) genome.

Three major repetitive DNA sequences were isolated from a genomic library of chickpea (Cicer arietinum L.) and characterized with respect to their genomic organization and chromosomal localization. All repetitive elements are genus-specific and mostly located in the AT-rich pericentric heterochromatin. Two families are organized as satellite DNAs with repeat lengths of 162-168 bp (CaSat1) and 100 bp (CaSat2). CaSat1 is mainly located adjacent to the 18S rDNA clusters on chromosomes A and B, whereas CaSat2 is a major component of the pericentric heterochromatin on all chromosomes. The high abundance of these sequences in closely related species of the genus Cicer as well as their variation in structure and copy number among the annual species provide useful tools for taxonomic studies. The retrotransposon-like sequences of the third family (CaRep) display a more complex organization and are represented by two independent sets of clones (CaRep1 and CaRep2) with homology to different regions of Ty3-gypsy-like retrotransposons. They are distributed over the pericentric heterochromatin block on all chromosomes with extensions into euchromatic regions. Conserved structures within different crossability groups of related Cicer species suggest independent amplification or transposition events during the evolution of the annual species of the genus.

Amino Acid Sequence↗
PubMed1997

Gene structure and chromosome localization of the G gamma c subunit of human cone G-protein (GNGT2).

Phototransduction in the vertebrate rod and cone photoreceptors is regulated by structurally homologous and yet distinct groups of signaling proteins. We have previously identified in bovine retinas a cone-specific G-protein gamma subunit (G gamma c, previously named G gamma b), which may play a key role in coupling the cone visual pigment to phosphodiesterase (O. C. Ong et al., 1995, J. Biol. Chem. 270:8495-8500). We report here the characterization of human G gamma c and its gene structure. Human G gamma c subunit shares a high degree of sequence identity with the corresponding bovine G gamma c isoform (85%) and human rod G gamma 1 (63%). The protein is specifically localized in cones, as indicated by immunohistochemical staining using anti-G gamma c antibodies. Nucleotide sequence analysis of the G gamma c gene (GNGT2) reveals a structure consisting of three exons and two introns, with the intron splice sites similar to that of the rod G gamma 1 gene (GNGT1). By using fluorescence in situ hybridization, we have further localized the human GNGT2 gene to chromosome 17q21. The elucidation of the G gamma c gene structure would facilitate the identification of genetic defects associated with cone degeneration.

Amino Acid Sequence↗
PubMed1996

Genomic structure and chromosomal localization of the mouse CDEI-binding protein CDEBP (APLP2) gene and promoter sequences.

The genomic structure of the mouse gene encoding the CDEBP protein has been established. The protein was initially identified on the basis of its ability to bind the CDEI motif (GTCACATG). The same locus has been independently described under the name APLP2, on the basis of sequence similarities with the Amyloid Precursor Protein (APP). The exon-intron distribution of Cdebp appears strikingly similar to that of the App gene in the regions encoding the conserved domains, with a divergent structure in the other parts. The transcription start site has been localized, and sequences with promoter activity have been identified immediately upstream of it by their ability to direct the expression of a reporter luciferase gene in transfected cells. This region is devoid of either TATA or CAAT boxes. The gene has been mapped to mouse chromosome 9 by in situ hybridization on metaphase chromosomes.

Animals↗
PubMed1996

Molecular cloning, structure, and chromosomal localization of the mouse LIM/homeobox gene Lhx5.

Lhx5, the mouse ortholog of the Xenopus Xlim-5, is a LIM/homeobox gene expressed in the central nervous system during both embryonic development and adulthood. During development its domain of expression is mainly localized at the most anterior portion of the neural tube, and it precedes the morphological differentiation of the forebrain; for this reason we believe that Lhx5 could play an important role in forebrain patterning. Here we present the structural organization and the chromosomal localization of the Lhx5 gene. The gene is composed of five exons spanning more than 10 kb of genomic sequence. The first and second LIM domains are encoded by the first and second exon, while the codons of the homeobox are split between the third and the fourth exons. The structure of Lhx5 is similar to that of other LIM/homeodomain proteins, Lhx1/lim1 and Lhx3/lim3, but differs from that of other LIM genes, such as mec3 and LMO1/Rbtn1, in which the codons for the LIM domains are interrupted by introns. We have mapped Lhx5 to the central region of mouse chromosome 5.

Animals↗
PubMedDate not supplied

[Streptomycetes--producers of polyketide antibiotics].

The review is dedicated to biosynthesis of polyketides compounds by streptomycetes. It contains new data about structure of streptomycete chromosome, structure and action mechanism of polyketidesynthases of I and II types and gene clusters determining the biosynthesis of polyketides. A new promising approach is considered--the combinatorial biosynthesis of hybrid "unnatural" antibiotics by means of gene engineering construction of recombinant strains bearing the biosynthetic genes of bacterial aromatic polyketidesynthases.

Anti-Bacterial Agents↗
PubMed1999

Chromatin remodeling and transcriptional regulation.

Extensive studies in the past few years have begun to demonstrate that chromosome structure plays a critical role in transcriptional regulation. Two highly conserved mechanisms for altering chromosome structure have been identified: 1) post-translational modification of histones and 2) adenosine triphosphate (ATP)-dependent chromosome remodeling. Acetylation of histone lysine residues has been known for three decades to be associated with transcriptional activation. Recent discoveries, however, show that a number of transcriptional regulators are histone acetylases or histone deacetylases. Specific DNA-binding transcription factors recruit histone acetylases and deacetylases to promoters to activate or repress transcription. These results strongly support the notion that histone acetylation and deacetylation play an important role in transcriptional regulation. Recent findings have also provided insight into the molecular mechanisms by which ATP-dependent chromosome-remodeling activities participate in transcriptional regulation. Furthermore, some ATP-dependent chromosome-remodeling activities have been shown to complex with histone deacetylases. In the complexes studied to date, the ATP-dependent chromosome-remodeling activity enhances the histone deacetylase activity. Therefore, the two mechanisms appear to work in concert to achieve precise control of transcription. Disruption of chromosome remodeling has been linked to a number of diseases, and a complete understanding of the complex chromosome-remodeling machinery may lead to the development of new therapies.

Acetylation↗
PubMed1998

Evolution of the structure and chromosomal distribution of histidine biosynthetic genes.

A database of more than 100 histidine biosynthetic genes from different organisms belonging to the three primary domains has been analyzed, including those found in the now completely sequenced genomes of Haemophilus influenzae, Mycoplasma genitalium, Synechocystis sp., Methanococcus jannaschii, and Saccharomyces cerevisiae. The ubiquity of his genes suggests that it is a highly conserved pathway that was probably already present in the last common ancestor of all extant life. The chromosomal distribution of the his genes shows that the enterobacterial histidine operon structure is not the only possible organization, and that there is a diversity of gene arrays for the his pathway. Analysis of the available sequences shows that gene fusions (like those involved in the origin of the Escherichia coli and Salmonella typhimurium hisIE and hisB gene structures) are not universal. In contrast, the elongation event that led to the extant hisA gene from two homologous ancestral modules, as well as the subsequent paralogous duplication that originated hisF, appear to be irreversible and are conserved in all known organisms. The available evidence supports the hypothesis that histidine biosynthesis was assembled by a gene recruitment process.

Archaea↗
PubMed1999

Synthetic lethal phenotypes caused by mutations affecting chromosome partitioning in Bacillus subtilis.

We investigated the genetic interactions between mutations affecting chromosome structure and partitioning in Bacillus subtilis. Loss-of-function mutations in spoIIIE (encoding a putative DNA translocase) and smc (involved in chromosome structure and partitioning) caused a synthetic lethal phenotype. We constructed a conditional mutation in smc and found that many of the spoIIIE smc double-mutant cells had a chromosome bisected by a division septum. The growth defect of the double mutant was exacerbated by a null mutation in the chromosome partitioning gene spo0J. These results suggest that mutants defective in nucleoid structure are unable to move chromosomes out of the way of the invaginating septum and that SpoIIIE is involved in repositioning these bisected chromosomes during vegetative growth.

Bacillus subtilis↗
PubMed2005

Chromosome-level homeology in paleopolyploid soybean (Glycine max) revealed through integration of genetic and chromosome maps.

Soybean has 20 chromosome pairs that are derived from at least two rounds of genomewide duplication or polyploidy events although, cytogenetically, soybean behaves like a diploid and has disomic inheritance for most loci. Genetically anchored genomic clones were used as probes for fluorescence in situ hybridization (FISH) to determine the level of postpolyploid chromosomal rearrangements and to integrate the genetic and physical maps to (1) assign linkage groups to specific chromosomes, (2) assess chromosomal structure, and (3) determine the distribution of recombination along the length of a chromosome. FISH mapping of seven putatively gene-rich BACs from linkage group L (chromosome 19) revealed that most of the genetic map correlates to the highly euchromatic long arm and that there is extensive homeology with another chromosome pair, although colinearity of some loci does appear to be disrupted. Moreover, mapping of BACs containing high-copy sequences revealed sequestration of high-copy repeats to the pericentromeric regions of this chromosome. Taken together, these data present a model of chromosome structure in a highly duplicated but diploidized eukaryote, soybean.

Chromosomes, Artificial, Bacterial↗
PubMed1990

A case of malignant mastocytosis with near-haploid, near-diploid, and polyploid cells in the bone marrow.

Chromosome analysis in bone marrow cells of a 41-year-old woman with malignant mastocytosis (MM) revealed near-haploid (59%), near-diploid (36%), and polyploid (5%) cells. Near-haploid cells had a mode of 25 chromosomes with variable disomy and nullisomy of particular chromosomes. Disomy for chromosome 19 and chromosome 20 were most common. A 17p+ marker was observed in all cells. Other structural chromosomal changes were dicentrics, ring chromosomes, translocations, and double minutes. The modal chromosome number in near-diploid cells was 46 with a range of 41-52. The majority of cells with 46 chromosomes were pseudodiploid and only a few had a normal female karyotype. As in near-haploid cells, various structural chromosomal changes were found. The 17p+ marker was also present in occasional cells suggesting a relationship between the two tumor cell populations. Chromosome numbers in polyploid cells ranged from 70 to about 600. Identical copies of dicentrics or markers were identified in some cells.

Adult↗