Genetic mapping and developmental timing of transmission ratio distortion in a mouse interspecific backcross

Background

Sheep carcasses with yellow fat are sporadically observed at Norwegian slaughter houses. This phenomenon is known to be inherited as a recessive trait, and is caused by accumulation of carotenoids in adipose tissue. Two enzymes are known to be important in carotenoid degradation in mammals, and are therefore potential candidate genes for this trait. These are beta-carotene 15,15'-monooxygenase 1 (BCMO1) and the beta-carotene oxygenase 2 (BCO2).

Results

In the present study the coding region of the BCMO1 and the BCO2 gene were sequenced in yellow fat individuals and compared to the corresponding sequences from control animals with white fat. In the yellow fat individuals a nonsense mutation was found in BCO2 nucleotide position 196 (c.196C>T), introducing a stop codon in amino acid position 66. The full length protein consists of 575 amino acids. In spite of a very low frequency of this mutation in the Norwegian AI-ram population, 16 out of 18 yellow fat lambs were found to be homozygous for this mutation.

Conclusion

In the present study a nonsense mutation (c.196C>T) in the beta-carotene oxygenase 2 (BCO2) gene is found to strongly associate with the yellow fat phenotype in sheep. The existence of individuals lacking this mutation, but still demonstrating yellow fat, suggests that additional mutations may cause a similar phenotype in this population. The results demonstrate a quantitatively important role for BCO2 in carotenoid degradation, which might indicate a broad enzyme specificity for carotenoids. Animals homozygous for the mutation are not reported to suffer from any negative health or development traits, pointing towards a minor role of BCO2 in vitamin A formation. Genotyping AI rams for c.196C>T can now be actively used in selection against the yellow fat trait.     

Localization of the murine methylmalonyl CoA mutase (Mut) locus on chromosome 17 by in situ hybridization

Murine methylmalonyl CoA mutase (Mut) has been localized to chromosome 17C-D by in situ hybridization in cell line containing a 2.17 Robertsonian translocation. This locus, which was mapped with the help of a murine methylmalonyl CoA mutase cDNA probe, and others on murine chromosome 17 are syntenic, though not necessarily colinear, with loci on human chromosome 6.     

DORMANCY IN SEEDS OF FRASERA CAROLINIENSIS (GENTIAN ACEAE)

In freshly matured seeds of the long-lived monocarpic perennial, Frasera caroliniensis Walt., the embryos are underdeveloped and physiologically dormant. Dormancy was broken by a long period of stratification (chilling) at 5 C. Seventy six percent of the seeds germinated at 20 C (day)/10 C (night) after 98 days of chilling at 5 C, while seeds kept at 5 C germinated to 87% after 205 days. A warm, moist pretreatment was not required for subsequent breaking of dormancy at 5 C. Embryos in fresh seeds averaged 1.3 mm long, but after 12 weeks of chilling they averaged 4.1 mm. Thus, the embryos require a period of chilling to become fully developed, after which seeds can germinate at the afterripening temperatures (5 C) or at some higher temperature. Seeds of F. caroliniensis fit Nikolaeva's (1977) morpho-physiological complex dormancy type.     

Metabolism of the anticancer agent 1-(4-acetylphenyl)-3,3-dimethyltriazene

High pressure liquid chromatography was used in combination with mass spectrometry to confirm that the main products of in vitro metabolism of 1-(4-acetylphenyl)-3,3-dimethyltriazene are 1-(4-acetylphenyl-3-methyltriazene and 4-aminoacetophenone. In addition a novel metabolite, 1-[4-(1-hydroxyethyl)-phenyl]-3,3-dimethyltriazene, possessing antitumour activity similar to the parent drug, was identified.     

The nonhistone proteins of developing mammalian erythroid cells

Anaemic rabbit bone marrow cells, labelled with [35S]methionine, were separated at unit gravity. Chromatin was isolated from these cells and proteins were separated from DNA, using urea/salt extraction. Two-dimensional gel electrophoresis of the nonhistone proteins showed that these proteins appeared to change quantitatively but not qualitatively, with one important exception, as cell development proceeded. The one protein that did change had a molecular weight of approximately 20,000 and was very basic. This protein was synthesised at low levels in the early cells, but its synthesis was seen to increase at the polychromatic stage of cell development, just prior to nuclear condensation. Treatment of bone marrow cells with sodium butyrate was shown to increase the synthesis of this protein in the early cells.     

PARP10 Influences the Proliferation of Colorectal Carcinoma Cells,a Preliminary Study

PARP10 is an intracellular mono-ADP ribosyltransferase and recent reports suggest that it regulates proliferation of some cell types. However, its effect on the proliferation of colorectal carcinoma cells has not yet been systematically reported. We explored the influence of PARP10 on the proliferation of several colorectal carcinoma cell types and carried out initial studies on the underlying mechanisms. Inhibition of the enzymatic activity of PARP10 led to significantly decreases in proliferative ability in LoVo cells and CT26 cells in vitro and suppressed growth of CT26 tumours in the subaxilliary region in Balb/c mice in vivo. Cell-cycle arrest accompanied these observations. Expression of the nuclear transfer factor β-catenin and it translocation to the nucleus were also affected and the expression of its associated signal proteins Axin2 and c-Myb were increased and decreased, respectively. We demonstrate that PARP10 promotes proliferation of those colorectal carcinoma cells which express significant levels of PARP10. This promotion is suppressed when the enzymatic activity is inhibited. β-Catenin is likely to be the mediator of the antiproliferative effect.     

Identification and Characterization of an Invasion Antigen B Gene from the Oral Pathogen Campylobacter rectus

The oral bacterium, Campylobacter rectus, is an etiological agent of periodontitis. The virulence genes of C. rectus are largely unknown. The aim of this study was to query C. rectus for the presence of an invasion antigen B (ciaB) gene, which is needed for cell invasion by the related species Campylobacter jejuni. PCR and PCR-walking identified a ciaB from C. rectus. In silico analyses of C. rectus 314 ciaB (Cr-ciaB) revealed an ORF of 1,830 base pairs. The Cr-CiaB protein shared significant sequence identity (BLASTx and phylogeny) with CiaB from related campylobacters. Cr-CiaB is predicted to lack membrane helices, signal peptides, and localizes to the cytoplasm; which are consistent with CiaB proteins. Expression of Cr-ciaB was confirmed with RT-PCR; and potential ciaB genes were detected in eight additional strains of C. rectus. Cr-ciaB is the first CiaB identified from the oral campylobacters.     

Syntenic Assignment of Human Chromosome 1 Homologous Loci in the Bovine

Three mouse chromosomes (MMU 1, 3, and 4) carry homologs of human chromosome 1 (HSA 1) genes. A similar situation is found in the bovine, where five bovine chromosomes (BTA 2, 3, 5, 16, and unassigued syntenic group U25) contain homologs of HSA 1 loci. To evaluate further the syntenic relationship of HSA 1 homologs in cattle, 10 loci have been physically mapped through segregation analysis in bovine-rodent hybrid somatic cells. These loci, chosen for their location on HSA 1, are antithrombin 3 (AT3), renin (REN), complement component receptor 2 (CR2), phosphofructokinase muscle type (PFKM), Gardner-Rasheed feline sarcoma viral (v-fgr) oncogene homolog (FGR), α fucosidase (FUCA1), G-protein β1 subunit (GNB1), α 1A amylase, (AMY1), the neuroblastoma RAS viral (v-ras) oncogene homolog (NRAS), and α skeletal actin (ACTA1). AT3, REN, CR2, and GNB1 mapped to BTA 16, PFKM to BTA 5, AMY1A and NRAS to BTA 3, FGR and FUCA1 to BTA 2, and ACTA1 to BTA 28.