Whole genome scan identifies several chromosomal regions linked to equine sarcoids.

Despite the evidence for a genetic predisposition to develop equine sarcoids (ES), no whole genome scan for ES has been performed to date. The objective of this explorative study was to identify chromosome regions associated with ES. The studied population was comprised of two half-sibling sire families, involving a total of 222 horses. Twenty-six of these horses were affected with ES. All horses had been previously genotyped with 315 microsatellite markers. Quantitative trait locus (QTL) signals were suggested where the F statistic exceeded chromosome-wide significance at P < 0.05. The QTL analyses revealed significant signals reaching P < 0.05 on equine chromosome (ECA) 20, 23 and 25, suggesting a polygenic character for this trait. The candidate regions identified on ECA 20, 23 and 25 include genes regulating virus replication and host immune response. Further investigation of the chromosome regions associated with ES and of genes potentially responsible for the development of ES could form the basis for early identification of susceptible animals, breeding selection or the development of new therapeutic targets.

Map positions of third chromosomal female sterile and lethal mutations of Drosophila melanogaster

Chromosomal mutations induced by ethyl methanesulfonate (EMS) treatment can cause female sterility or maternal-effect lethality in Drosophila. EMS is particularly useful to researchers because it creates mutations independent of position effects. However, because researchers have little control over the chromosomal site of mutation, post-mutagenic genetic mapping is required to determine the cytological location of the mutation. To make a valuable set of mutants more useful to the research community, we have mapped the uncharacterized part of the female-sterile – maternal-effect lethal Tübingen collection. We mapped 49 female-sterile – maternal-effect lethal alleles and 72 lethal alleles to individual deficiency intervals on the third chromosome. In addition, we analyzed the phenotype of ovaries resulting from female sterile mutations. The observed phenotypes range from tumorous ovaries and early blocks in oogenesis, to later blocks, slow growth, blocks in stage 10, to apparently full development of the ovary. The mapping and phenotypic characterization of these 121 mutations provide the necessary information for the researcher to consider a specific mutant as a candidate for their gene of interest.Key words: Drosophila melanogaster, oogenesis, female sterile, maternal-effect lethal, EMS-induced mutations.

Melanotic tumors of the nervous system are characterized by distinct mutational, chromosomal and epigenomic profiles.

Melanotic tumors of the nervous system show overlapping histological characteristics but differ substantially in their biological behavior. In order to achieve a better delineation of such tumors, we performed an in-depth molecular characterization. Eighteen melanocytomas, 12 melanomas, and 14 melanotic and 14 conventional schwannomas (control group) were investigated for methylome patterns (450k array), gene mutations associated with melanotic tumors and copy number variants (CNVs). The methylome fingerprints assigned tumors to entity-specific groups. Methylation groups also showed a substantial overlap with histology-based diagnosis suggesting that they represent true biological entities. On the molecular level, melanotic schwannomas were characterized by a complex karyotype with recurrent monosomy of chromosome 22q and variable whole chromosomal gains and recurrent losses commonly involving chromosomes 1, 17p and 21. Melanocytomas carried GNAQ/11 mutations and presented with CNV involving chromosomes 3 and 6. Melanomas were frequently mutated in the TERT promoter, harbored additional oncogene mutations and showed recurrent chromosomal losses involving chromosomes 9, 10 and 6q, as well as gains of 22q. Together, melanotic nervous system tumors have several distinct mutational and chromosomal alterations and can reliably be distinguished by methylome profiling.

Chromosomal assignment of the canine melanophilin gene (MLPH): a candidate gene for coat color dilution in Pinschers

Pinschers affected by coat color dilution show a specific pigmentation phenotype. The dilute pigmentation phenotype leads to a silver-blue appearance of the eumelanin-containing fur and a pale sandy color of pheomelanin-containing fur. In Pinscher breeding, dilute black-and-tan dogs are called "blue," and dilute red or brown animals are termed "fawn" or "Isabella fawn." Coat color dilution in Pinschers is sometimes accompanied by hair loss and a recurrent infection of the hair follicles. In human and mice, several well-characterized genes are responsible for similar pigment variations. To investigate the genetic cause of the coat color dilution in Pinschers, we isolated BAC clones containing the canine ortholog of the known murine color dilution gene Mlph. RH mapping of the canine MLPH gene was performed using an STS marker derived from BAC sequences. Additionally, one MLPH BAC clone was used as probe for FISH mapping, and the canine MLPH gene was assigned to CFA25q24.

Molecular characterization and chromosomal assignment of the bovine glycinamide ribonucleotide formyltransferase (GART) gene on cattle chromosome 1q12.1-q12.2

The mammalian glycinamide ribonucleotide formyltransferase (GART) genes encode a trifunctional polypeptide involved in the de novo purine biosynthesis. We isolated a bacterial artificial chromosome (BAC) clone containing the bovine GART gene and determined the complete DNA sequence of the BAC clone. Cloning and characterization of the bovine GART gene revealed that the bovine gene consists of 23 exons spanning approximately 27 kb. RT-PCR amplification of bovine GART in different organs showed the expression of two GART transcripts in cattle similar to human and mouse. The GART transcripts encode two proteins of 1010 and 433 amino acids, respectively. Eleven single nucleotide polymorphisms (SNPs) were detected in a mutation scan of 24 unrelated animals of three different cattle breeds, including one SNP that affects the amino acid sequence of GART. The chromosomal localization of the gene was determined by fluorescence in situ hybridization. Comparative genome analysis between cattle, human and mouse indicates that the chromosomal location of the bovine GART gene is in agreement with a previously published mapping report.

37,X/38,XY Mosaicism in a Cryptorchid Bengal Cat with Müllerian Duct Remnants

A 23-month-old tomcat was referred to our clinic because of male behavioral problems, cryptorchidism, and an undefined intra-abdominal organ resembling a uterus. Ultrasonography and computed tomography showed 2 fluid-filled tubular structures dorsolaterally to the bladder and connected to the pelvic urethra. The cat was castrated, and the tubular structures were surgically removed. Histology identified them as Müllerian duct remnants. The testes were hypoplastic, the epididymes and deferent ducts were normal. Cytogenetic analyses revealed the presence of a mosaic 37,X/38,XY karyotype which explains the clinical findings.

ETIOLOGIC AND CLINICAL FACTORS WHICH DIFFERENTIATE PATIENTS WITH CHROMOSOMAL ABNORMALITIES FROM DIPLOID PATIENTS IN ACUTE NONLYMPHOCYTIC LEUKEMIA

Tumor-specific chromosomal abnormalities have been demonstrated in bone marrow of approximately 50% of newly diagnosed acute nonlymphocytic (ANLL) patients. This study examined two hypotheses: (1) Aneuploid (AA) patients are diagnosed later in the course of their disease than diploid (NN) patients; and (2) AA patients are more likely to have been exposed to environmental agents. Of 324 patients eligible for study, environmental exposure data were obtained for 236 (73%) of them. No evidence was found to suggest that AA patients had more advanced disease than NN patients. Aneuploid patients were more likely than NN patients to: (a) report treatment with cytotoxic drugs for a prior medical condition (odds ratio, adjusted for age, sex and other exposures (OR) = 4.25, 95% confidence intervals, 1.38 to 13.17); (b) smoke cigarettes, OR = 1.82 (1.02, 3.26) and (c) drink alcoholic beverages, OR = 1.91 (1.05, 3.48). No statistically significant associations between aneuploidy and occupational exposures were present, OR = 3.59 (0.76, 17.13). Problems in interpreting these ORs are discussed. ^

Human carbonic anhydrase XII: cDNA cloning, expression, and chromosomal localization of a carbonic anhydrase gene that is overexpressed in some renal cell cancers

We report the cloning and characterization of a tumor-associated carbonic anhydrase (CA) that was identified in a human renal cell carcinoma (RCC) by serological expression screening with autologous antibodies. The cDNA sequence predicts a 354-amino acid polypeptide with a molecular mass of 39,448 Da that has features of a type I membrane protein. The predicted sequence includes a 29-amino acid signal sequence, a 261-amino acid CA domain, an additional short extracellular segment, a 26-amino acid hydrophobic transmembrane domain, and a hydrophilic C-terminal cytoplasmic tail of 29 amino acids that contains two potential phosphorylation sites. The extracellular CA domain shows 30–42% homology with known human CAs, contains all three Zn-binding histidine residues found in active CAs, and contains two potential sites for asparagine glycosylation. When expressed in COS cells, the cDNA produced a 43- to 44-kDa protein in membranes that had around one-sixth the CA activity of membranes from COS cells transfected with the same vector expressing bovine CA IV. We have designated this human protein CA XII. Northern blot analysis of normal tissues demonstrated a 4.5-kb transcript only in kidney and intestine. However, in 10% of patients with RCC, the CA XII transcript was expressed at much higher levels in the RCC than in surrounding normal kidney tissue. The CA XII gene was mapped by using fluorescence in situ hybridization to 15q22. CA XII is the second catalytically active membrane CA reported to be overexpressed in certain cancers. Its relationship to oncogenesis and its potential as a clinically useful tumor marker clearly merit further investigation.

Loss of heterozygosity induced by a chromosomal double-strand break

The repair of chromosomal double-strand breaks (DSBs) is necessary for genomic integrity in all organisms. Genetic consequences of misrepair include chromosomal loss, deletion, and duplication resulting in loss of heterozygosity (LOH), a common finding in human solid tumors. Although work with radiation-sensitive cell lines suggests that mammalian cells primarily rejoin DSBs by nonhomologous mechanisms, alternative mechanisms that are implicated in chromosomal LOH, such as allelic recombination, may also occur. We have examined chromosomal DSB repair between homologs in a gene targeted mammalian cell line at the retinoblastoma (Rb) locus. We have found that allelic recombinational repair occurs in mammalian cells and is increased at least two orders of magnitude by the induction of a chromosomal DSB. One consequence of allelic recombination is LOH at the Rb locus. Some of the repair events also resulted in other types of genetic instability, including deletions and duplications. We speculate that mammalian cells may have developed efficient nonhomologous DSB repair processes to bypass allelic recombination and the potential for reduction to homozygosity.

The human XRCC9 gene corrects chromosomal instability and mutagen sensitivities in CHO UV40 cells

The Chinese hamster ovary (CHO) mutant UV40 cell line is hypersensitive to UV and ionizing radiation, simple alkylating agents, and DNA cross-linking agents. The mutant cells also have a high level of spontaneous chromosomal aberrations and 3-fold elevated sister chromatid exchange. We cloned and sequenced a human cDNA, designated XRCC9, that partially corrected the hypersensitivity of UV40 to mitomycin C, cisplatin, ethyl methanesulfonate, UV, and γ-radiation. The spontaneous chromosomal aberrations in XRCC9 cDNA transformants were almost fully corrected whereas sister chromatid exchanges were unchanged. The XRCC9 genomic sequence was cloned and mapped to chromosome 9p13. The translated XRCC9 sequence of 622 amino acids has no similarity with known proteins. The 2.5-kb XRCC9 mRNA seen in the parental cells was undetectable in UV40 cells. The mRNA levels in testis were up to 10-fold higher compared with other human tissues and up to 100-fold higher compared with other baboon tissues. XRCC9 is a candidate tumor suppressor gene that might operate in a postreplication repair or a cell cycle checkpoint function.

Macrophage inflammatory protein-2: Chromosomal regulation in rat small intestinal epithelial cells

Nonpathogenic, resident bacteria participate in the pathogenesis of inflammation in the small intestine, but the molecular messages produced by such bacteria are unknown. Inflammatory responses involve the recruitment of specific leukocyte subsets. We, therefore, hypothesized that butyrate, a normal bacterial metabolite, may modulate chemokine secretion by epithelial cells, by amplifying their response to proinflammatory signals. We studied the expression of the chemokine, macrophage inflammatory protein-2 (MIP-2) by the rat small intestinal epithelial cell line, IEC-6. Cells were stimulated with lipopolysaccharide or with interleukin 1β (IL-1β) and incubated with sodium butyrate. Acetylation of histones was examined in Triton X acetic acid–urea gels by PAGE. Unstimulated IEC-6 cells did not secrete MIP-2. However, lipopolysaccharide and IL-1β induced MIP-2 expression. Butyrate enhanced MIP-2 secretion both in lipopolysaccharide-stimulated and IL-1β-stimulated enterocytes; but butyrate alone did not induce MIP-2 expression. Butyrate increased the acetylation of histones extracted from the nuclei of IEC-6 cells. Furthermore, acetylation of histones (induced by trichostatin A, a specific inhibitor of histone deacetylase) enhanced MIP-2 expression by cells stimulated with IL-1β. In conclusion, trichostatin A reproduced the effects of butyrate on MIP-2 secretion. Butyrate, therefore, increases MIP-2 secretion in stimulated cells by increasing histone acetylation. We speculate that butyrate carries information from bacteria to epithelial cells. Epithelial cells transduce this signal through histone deacetylase, modulating the secretion of chemokines.

The ARS309 chromosomal replicator of Saccharomyces cerevisiae depends on an exceptional ARS consensus sequence

Autonomously replicating sequence (ARS) elements, which function as the cis-acting chromosomal replicators in the yeast Saccharomyces cerevisiae, depend upon an essential copy of the 11-bp ARS consensus sequence (ACS) for activity. Analysis of the chromosome III replicator ARS309 unexpectedly revealed that its essential ACS differs from the canonical ACS at two positions. One of the changes observed in ARS309 inactivates other ARS elements. This atypical ACS binds the origin recognition complex efficiently and is required for chromosomal replication origin activity. Comparison of the essential ACS of ARS309 with the essential regions of other ARS elements revealed an expanded 17-bp conserved sequence that efficiently predicts the essential core of ARS elements.