Identifying QTL and genetic correlations between fur quality traits in mink (Neovison vison)

Mapping of QTL affecting fur quality traits (guard hair length, guard hair thickness, density of wool, surface of the fur and quality) and skin length was performed in a three‐generation mink population (F₂ design). In the parental generation, Nordic Brown mink were crossed reciprocally with American Black short nap mink. In all, 1082 mink encompassing three generations were used for the analyses. The mink were genotyped for 104 microsatellites covering all 14 autosomes. The QTL analyses were performed by least‐square regression implemented in gridqtl software. Genetic and phenotypic correlations and heritabilities were estimated using the average information‐restricted maximum‐likelihood method. Evidence was found for QTL affecting fur quality traits on nine autosomes. QTL were detected for guard hair thickness on chromosomes 1, 2, 3, 6 and 13; for guard hair length on chromosomes 2, 3 and 6; for wool density on chromosomes 6 and 13; for surface on chromosomes 7, 12 and 13; for quality on chromosomes 6, 7, 11 and 13; and for skin length on chromosomes 7 and 9. Proximity of locations of QTL for guard hair length, guard hair thickness and for wool density and quality suggests that some of the traits are in part under the influence of the same genes. Traits under the influence of QTL at close or identical positions also were traits that were strongly genotypically correlated. Based on the results of correlation analyses, the most important single traits influencing the quality were found to be density of wool, guard hair thickness and appearance of the surface.     

Hygrophiloside,an iridoid glucoside from Hygrophila difformis (Acanthaceae)

A new iridoid glucoside, hygrophiloside, has been isolated from Hygrophila difformis. Hygrophiloside is apparently identical to the so-called ‘Cardanthera-Pseudoindican’. Its structure has been established by spectroscopic means and by reduction to isoaucubin.     

Coordination of growth and differentiation in the fetal lung

The male fetal lung begins to synthesize surfactant later in gestation than the female. This delay appears to be caused by androgens. We hypothesized that male fetal lung differentiation is delayed as a consequence of an extended phase of growth which is elicited by androgens. We observed that in vivo fetal lung protein synthesis relative to DNA synthesis peaked earlier in gestation in the female fetal lung and that this event was synchronous with the onset of differentiation. Pregnant rats were treated with dihydrotestosterone (DHT) during pregnancy, and fetal lung growth parameters were measured. Lung wet weight, dry weight, and DNA and protein concentrations were significantly elevated by DHT treatment. Type II cells and fibroblasts were isolated from lungs of DHT-treated fetuses. The number of total cells recovered was increased by 30%; the number of type II cells recovered was increased by 87%; and the number of fibroblasts recovered was increased by 42%. The type II cells which were recovered exhibited increased incorporation of [3H]thymidine into DNA and a reduced ratio of radiolabeled protein to radiolabeled DNA compared to that of cells from control lungs. Further studies were done in vitro with fibroblasts and type II cells isolated from untreated fetal rat lungs. Treatment of the fibroblasts with DHT during culture caused an increase in thymidine incorporation into DNA. This effect was not blocked by simultaneous treatment with cortisol, which normally causes reduced DNA synthesis and induces fibroblast differentiation. Treatment of the type II cells with DHT in culture caused a dose-dependent increase in cell number but a decrease in synthesis of disaturated phosphatidylcholine. These studies provide more direct evidence of the interrelationships between the control of growth and the control of differentiation in the fetal lung. DHT, a signal which delays the onset of expression of differentiation, also induces growth. We conclude that the controls of growth and of differentiation of the fetal lung are reciprocally linked.     

The mutagenic effect of gamma rays on leaf protoplasts of haploid and dihaploid Nicotiana plumbaginifolia,estimated by valine resistance mutation frequencies

Summary Leaf protoplasts isolated from haploid and dihaploid Nicotiana plumbaginifolia plantlets were treated with different doses of gamma-rays and their survival was determined by scoring for plating efficiency at each irradiation dose. A fixed number of surviving protoplast-derived colonies was then plated in the presence of inhibitory concentrations of L-valine and incubated until growing resistant calli could be scored and mutation rates calculated. Though haploid protoplasts were found to be a little more sensitive than dihaploids to the lethal effect of radiation, the two dose-response curves of gamma-rays that induced mutagenesis were very similar. The irradiation dose capable of causing a ten-fold increase of spontaneous mutation frequencies was about 500 rads with both haploid and dihaploid protoplasts.Contribution No. 2173 of the Biology Radiation Protection and Medical Research Programme, Directorate General XII of the Commission of the European Communities     

Structural similarity between legumin and vicilin storage proteins from legumes.

The primary structures for several members of both the vicilin and legumin families of storage proteins were examined using a computer routine based on amino acid physical characteristics. The comparison algorithm revealed that sequences from the two families could be aligned and share a number of predicted secondary structural features. The COOH-terminal half of the subunits in both families displayed a highly conserved core region that was largely hydrophobic and in which a high proportion of the residues were predicted to be in beta-sheet conformations. The central region of the molecules which contained mixed areas of predicted helical and sheet conformations showed more variability in residue selection than the COOH-terminal regions. The NH2-terminal segments of subunits from the two different families could not be aligned though they characteristically had a high proportion of residues predicted to be in helical conformations. The feature which most clearly distinguished subunits between the two families was an inserted span in the legumin group with a high proportion of acidic amino acids located between the central and COOH-terminal domains. Residues in this insertion were predicted to exist mainly in helical conformation. Since considerable size variation occurs in this area amongst the legumin subunits, alterations in this region may have a minimal detrimental effect on the structure of the proteins.     

Gene probes to detect cross-culture contamination in hormone producing cell lines

Summary Cross-culture contamination of cell lines propagated in continuous culture is a frequent event and particularly difficult to resolve in cells expressing similar phenotypes. We demonstrate that DNA-DNA hybridization to blotted endonuclease-digested cell DNA effectively detects cross-culture contamination to monitor inter-species as well as intra-species cross contamination. An insulin-producing cell-line, Clone-16, originally cloned from a human fetal endocrine pancreatic cell line did not produce human c-peptide as anticipated. DNA from these cells showed no hybridization to the human ALU sequence probe, BLUR, and lacked restriction fragment length polymorphism typical for the human HLA-DQ β-chain gene. Although a human insulin gene probe showed a weak, nonhuman hybridization pattern, a cDNA probe for the Syrian hamster insulin gene hybridized strongly consistent with a single copy hamster insulin gene. Karyotyping confirmed the absence of human chromosomes in the Clone-16 cells while sizes, centromere indices, and banding patterns were identical to Syrian hamster fibroblasts. We conclude that the insulin-producing Clone-16 cells are of Syrian hamster origin and demonstrate the effective use of gene probes to control the origin of cell cultures. This paper is dedicated to the late Lis Lyngsie in much appreciation of her contributions to this study. This work was supported in part by the National Institutes of Health, Bethesda, MD (grants DK 26190 and 33873). I. Matsuba and B. Michelsen were supported by research fellowships from the Juvenile Diabetes Foundation International, and J. Scholler from the Danish Medical Research Council (J.no. 12-5758).     

Thymidylate Synthase in Plant Cells: Kinetic and Molecular Properties of the Enzyme from Daucus carota L. Cell Cultures

Thymidylate synthase activity was assayed in cell homogenatesfrom wild or domestic carrot (Daucus carota L.) suspension culturesusing the tritium-release method. The specific activity measuredwas lower than that previously reported for bacterial extracts,and its level did not change a great deal during a 14 day growthcycle. The enzyme was partially purified (about 9 fold) by ammoniumsulfate fractionation and ion-exchange chromatography. Kineticparameters such as pH optimum, K_m values for substrate and cofactor,and degree of inhibition by 5-fluoro-2'-deoxyuridine monophosphatewere characterized. The apparent mol wt, evaluated by gel-filtration chromatography,was 185 kDa, which was much higher than that reported for enzymesof bacterial and vertebrate origins and somewhat higher thanthat reported for the thymidylate synthase-dihydrofolate reductasebifunctional polypeptide of some protozoa. (Received April 20, 1987; Accepted February 15, 1988)     

Testosterone regulation of sex differences in fetal lung development.

Fetal lung development, in particular surfactant synthesis, exhibits a sexual dimorphism. Dihydrotestosterone (DHT) has been shown to delay fetal pulmonary surfactant production, but the potential role for testosterone is unknown. Both testosterone and DHT are potent masculinizing hormones, yet in some instances, an end organ specificity for DHT is present. We hypothesized that the delay in fetal lung surfactant production is dependent upon DHT such that inhibition of the synthesis of DHT from the precursor hormone testosterone would eliminate the sex difference by allowing the male fetus to produce surfactant at the female level. We tested this hypothesis using 17 beta-N,N-diethylcarbamoyl-4-aza-4-methyl-5-alpha-androstane-3-one (4-MA), a potent inhibitor of the enzyme 5 alpha-reductase, which converts testosterone into DHT. First, studies were performed in vivo. 4-MA (20 mg/kg/day) or an equivalent volume of vehicle was injected into pregnant rabbits from Day 12 through Day 26 of gestation. On Day 26, the fetuses were delivered, the lungs were lavaged, and fetal sex was noted. Treatment with 4-MA resulted in a lack of any male-female difference in the anogenital distance and no DHT was detected in the serum of any treated fetus. Phosphatidylcholine (PC), saturated phosphatidylcholine (SPC), and sphingomyelin (S) were measured in the lung lavage, and were expressed as the ratios of PC to sphingomyelin (PC:S) and SPC to sphingomyelin (SPC:S). Sex differences in the PC to sphingomyelin ratio of 4-MA-treated fetuses (female PC:S ratio, 1.43 +/- 0.14; male PC:S ratio, 1.00 +/- 0.13 [mean +/- SE]; P = 0.04) and in the SPC:S ratio of the 4-MA-treated group (female SPC:S ratio, 0.68 +/- 0.10; male SPC:S ratio, 0.35 +/- 0.10; P = 0.03) were present after treatment with 4-MA. The effect of testosterone and of 4-MA on fibroblast pneumonocyte factor (FPF) production was studied in vitro. Fetal rat lung fibroblasts were cultured to confluence with either no added androgen, DHT, testosterone, or testosterone plus 4-MA, and conditioned media for FPF were prepared. Conditioned media were added to fetal Type II cell cultures and FPF activity was measured as the degree of stimulation of the incorporation of [3H] choline into SPC. The conversion of radiolabeled testosterone to DHT by the fibroblasts was inhibited by 4-MA (10(-5) M). Conditioned media from untreated female fibroblasts stimulated with cortisol exhibited significant FPF activity ([3H]choline incorporation into SPC, 140 +/- 17% of control).(ABSTRACT TRUNCATED AT 400 WORDS)