Dominant cataract and recessive specific locus mutations in offspring of X-irradiated male mice

Male mice were X-irradiated with 3.0 + 3.0 Gy or 5.1 + 5.1 Gy (fractionation interval 24 h). The offspring were screened for dominant cataract and recessive specific locus mutations. In the 3.0 + 3.0-Gy spermatogonial treatment group, 3 dominant cataract mutations were confirmed in 15 551 offspring examined and 29 specific locus mutations were recovered in 18 139 offspring. In the post-spermatogonial treatment group, 1 dominant cataract mutation was obtained in 1120 offspring and 1 recessive specific locus mutation was recovered in 1127 offspring. The induced mutation rate per locus, per gamete, per Gy calculated for recessive specific locus mutations is 2.0 X 10(-5) in post-spermatogonial stages and 3.7 X 10(-5) in spermatogonia. For dominant cataract mutations, assuming 30 loci, the induced mutation rate is 5.0 X 10(-6) in the post-spermatogonial stages and 1.1 X 10(-6) in spermatogonia. In the 5.1 + 5.1-Gy spermatogonial treatment group, 3 dominant cataract mutations were obtained in 11 205 offspring, whereas in 13 201 offspring 27 recessive specific locus mutations were detected in the spermatogonial group. In the post-spermatogonial treatment group no dominant cataract mutation was observed in 425 offspring and 2 recessive specific locus mutations were detected in 445 offspring. The induced mutation rate per locus, gamete and Gy in spermatogonia for recessive specific locus mutations is 2.8 X 10(-5) and for dominant cataract mutations 0.9 X 10(-6). In post-spermatogonial stages, the mutation rate for recessive specific locus alleles is 6.2 X 10(-5). In the concurrent untreated control group, in 11 036 offspring no dominant cataract mutation and in 23 518 offspring no recessive specific locus mutation was observed. Litter size and the number of carriers at weaning have been determined in the confirmation crosses of the obtained dominant cataract mutants as indicators of viability and penetrance effects. Two mutants had a statistically significantly reduced litter size and one mutant had a statistically significantly reduced penetrance.     

Microsomal and cytosolic cytochrome P450 mediated benzo(a)pyrene hydroxylation in Pleurotus pulmonarius

Summary Microsomal and soluble fractions of Pleurotus pulmonarius exhibited a reduced carbon monoxide difference spectrum with P450 maxima at 448nm and 450–452nm respectively. Substrate induced Type I spectra were observed on addition of benzo(a)pyrene to both fractions. Benzo(a)pyrene hydroxylation was measured using the aryl hydrocarbon hydroxylase assay and was observed to be P450 dependent as indicated by carbon monoxide inhibition together with the substrate binding characteristics. The activity of the fractions were observed to give K_m of 200mM and 660mM and V_max of 1.25 nmol/min/nmol P450 and 0.57 nmol/min/nmol P450 for the microsomal and cytosolic fractions respectively.     

Hereditary Lactate Dehydrogenase a-Subunit Deficiency as Cause of Early Postimplantation Death of Homozygotes in Mus Musculus

Two ethylnitrosourea-induced heterozygous mouse mutants with approximately 58 and 50% of wild-type lactate dehydrogenase (LDH) activity and a gamma-ray-induced heterozygous mutant with 50% of wild-type LDH activity in blood, liver and spleen (expressing predominantly the Ldh-1 gene) were recovered in mutagenicity experiments following spermatogonial treatment. Physiological and genetic studies revealed no indications for differences in fertility as well as hematological or other physiological traits between heterozygotes of each mutant line and wild types. This suggests that neither the mutations in the heterozygous state per se nor the resulting approximate 42 to 50% LDH deficiency affect metabolism and fitness. Physicochemical and immunological studies clearly demonstrated that the two mutations with 50% deficiency in heterozygotes result from null alleles of the Ldh-1 structural locus, generating neither enzyme activity nor immunological cross-reacting material. In contrast, the heterozygous mutant with approximately 58% of normal blood LDH activity was shown to be due to a Ldh-1 allele creating protein subunits, which in random assortment with wild-type subunits in vivo exhibit a reduced specific activity and further alterations of kinetic and physicochemical characteristics. All the mutations in the homozygous state were found to be lethal at an early postimplantation stage of embryonic development, probably due to a block of glycolysis with the corresponding loss of the main source of metabolic energy during this ontogenetic stage. The distinct physiological consequences of the total absence of a functioning LDH-A subunit in mice and humans are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pathology of modified graft-versus-host disease in bone marrow allografted monkeys treated with antilymphocyte serum.

Lethally irradiated rhesus monkeys were used for bone marrow allografting and autografting. Monkeys receiving allogeneic bone marrow developed acute graft-versus-host reaction (GVHR) and had a mean survival time of 9.1 days as compared to autografted monkeys which survived above 500 days. Treatment with antilymphocyte sera (ALS) before allografting modified the GVHR and extended the survival time to an average of 43 days. Histologically, such animals showed evidence of "chronic" GVHR and septicemia secondary to a lack in lymphoreticular recovery. Subsequently, severe GI-tract infections followed which usually served as portal of entry for septicemia.     

Revisiting estimates of CTL killing rates in vivo

Recent experimental advances have allowed the estimation of the in vivo rates of killing of infected target cells by cytotoxic T lymphocytes (CTL). We present several refinements to a method applied previously to quantify killing of targets in the spleen using a dynamical model. We reanalyse data previously used to estimate killing rates of CTL specific for two epitopes of lymphocytic choriomeningitis virus (LCMV) in mice and show that, contrary to previous estimates the "killing rate" of effector CTL is approximately twice that of memory CTL. Further, our method allows the fits to be visualized, and reveals one potentially interesting discrepancy between fits and data. We discuss extensions to the basic CTL killing model to explain this discrepancy and propose experimental tests to distinguish between them.     

Aphidicolin induces 6-thioguanine resistant mutants in human diploid fibroblasts

Cytotoxic and mutagenic effects of aphidicolin (APC), an inhibitor of DNA polymerases alpha and delta, were studied in human diploid VH-10 fibroblasts. The cells were treated (2 or 4h) with APC at concentration ranges of 10-40 microM. The effect of APC on cell survival after 4 h treatment was significantly higher than after 2 h treatment. The mutagenicity of APC was investigated at the HPRT locus, and the frequency of HPRT mutants was estimated by selection in medium containing 6-thioguanine (6-TG). Treatment of fibroblast cells with 20 microM of APC for 2 or 4 h resulted approximately in 5 or 10 times increase of 6-TG resistant mutant frequencies, respectively, compared to untreated control cells.The cell cycle analyses performed during the expression time (9-12 days) have shown that after 2 and 4h treatment with APC the cells were blocked in G2 phase during the majority of the expression period, compared to control cells. Four days after the treatment, the amount of cells in G2 phase increased about two-fold (28.6-31.8% compared to 13.5% in the untreated cells). The mode of cell death during the expression time was via necrosis, rather than apoptosis, which was demonstrated by fluorescein-diacetate (FDA)-staining and terminal dUTP nick end labeling (TUNEL)-method.     

Out of Africa and back again: nested cladistic analysis of human Y chromosome variation

We surveyed nine diallelic polymorphic sites on the Y chromosomes of 1,544 individuals from Africa, Asia, Europe, Oceania, and the New World. Phylogenetic analyses of these nine sites resulted in a tree for 10 distinct Y haplotypes with a coalescence time of approximately 150,000 years. The 10 haplotypes were unevenly distributed among human populations: 5 were restricted to a particular continent, 2 were shared between Africa and Europe, 1 was present only in the Old World, and 2 were found in all geographic regions surveyed. The ancestral haplotype was limited to African populations. Random permutation procedures revealed statistically significant patterns of geographical structuring of this paternal genetic variation. The results of a nested cladistic analysis indicated that these geographical associations arose through a combination of processes, including restricted, recurrent gene flow (isolation by distance) and range expansions. We inferred that one of the oldest events in the nested cladistic analysis was a range expansion out of Africa which resulted in the complete replacement of Y chromosomes throughout the Old World, a finding consistent with many versions of the Out of Africa Replacement Model. A second and more recent range expansion brought Asian Y chromosomes back to Africa without replacing the indigenous African male gene pool. Thus, the previously observed high levels of Y chromosomal genetic diversity in Africa may be due in part to bidirectional population movements. Finally, a comparison of our results with those from nested cladistic analyses of human mtDNA and beta-globin data revealed different patterns of inferences for males and females concerning the relative roles of population history (range expansions) and population structure (recurrent gene flow), thereby adding a new sex-specific component to models of human evolution.      

Association of 25-Hydroxyvitamin D status and genetic variation in the vitamin D metabolic pathway with FEV1 in the Framingham Heart Study

Background

Vitamin D is associated with lung function in cross-sectional studies, and vitamin D inadequacy is hypothesized to play a role in the pathogenesis of chronic obstructive pulmonary disease. Further data are needed to clarify the relation between vitamin D status, genetic variation in vitamin D metabolic genes, and cross-sectional and longitudinal changes in lung function in healthy adults.

Methods

We estimated the association between serum 25-hydroxyvitamin D [25(OH)D] and cross-sectional forced expiratory volume in the first second (FEV₁) in Framingham Heart Study (FHS) Offspring and Third Generation participants and the association between serum 25(OH)D and longitudinal change in FEV₁ in Third Generation participants using linear mixed-effects models. Using a gene-based approach, we investigated the association between 241 SNPs in 6 select vitamin D metabolic genes in relation to longitudinal change in FEV₁ in Offspring participants and pursued replication of these findings in a meta-analyzed set of 4 independent cohorts.

Results

We found a positive cross-sectional association between 25(OH)D and FEV₁ in FHS Offspring and Third Generation participants (P = 0.004). There was little or no association between 25(OH)D and longitudinal change in FEV₁ in Third Generation participants (P = 0.97). In Offspring participants, the CYP2R1 gene, hypothesized to influence usual serum 25(OH)D status, was associated with longitudinal change in FEV₁ (gene-based P < 0.05). The most significantly associated SNP from CYP2R1 had a consistent direction of association with FEV₁ in the meta-analyzed set of replication cohorts, but the association did not reach statistical significance thresholds (P = 0.09).

Conclusions

Serum 25(OH)D status was associated with cross-sectional FEV₁, but not longitudinal change in FEV₁. The inconsistent associations may be driven by differences in the groups studied. CYP2R1 demonstrated a gene-based association with longitudinal change in FEV₁ and is a promising candidate gene for further studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0238-y) contains supplementary material, which is available to authorized users.