Population genetic characterization of the Japanese oak silkmoth, Antheraea yamamai (Lepidoptera: Saturniidae), using novel microsatellite markers and mitochondrial DNA gene sequences.

The Japanese oak silkmoth, Antheraea yamamai Guérin-Méneville, 1861 (Lepidoptera: Saturniidae), is an important natural resource of industrial value for silk fiber production. Owing to a lack of geographic and population genetic information, systematic domestication of An. yamamai has not been possible yet. In this study, 10 microsatellite markers developed using next-generation sequencing and two mitochondrial DNA (mtDNA) gene sequences (COI and ND4) were used to investigate the genetic variation and geographic structure of An. yamamai populations in South Korea. The two mtDNA gene sequences revealed very low total genetic variation and, consequently, low geographic variation, validating the use of more variable molecular markers. Genotyping of 76 An. yamamai individuals from nine localities in South Korea showed that the observed number of alleles at each locus ranged from 3 to 26, the polymorphism information content was 0.2990-0.9014, the observed and expected heterozygosities were 0.3252-0.9076 and 0.2500-0.9054, respectively, and FIS was -0.654-0.520. The population-based FIS, FST, RST, and global Mantel tests all suggested that the An. yamamai populations were overall well-interconnected, suggesting that any population can be used as a genetic source for domestication. Nevertheless, STRUCTURE analyses using microsatellite data and mtDNA sequences indicated the presence of two genetic pools in many populations, although a plausible explanation for this observation requires further studies.

Usefulness of direct sequencing of pooled DNA for SNP identification and allele-frequency determination compatible with a common disease/common variant hypothesis.

We examined the efficiency of direct sequencing of pooled DNA for developing common single nucleotide polymorphisms (SNPs) and its accuracy for estimating allele frequencies. A pool of 200 control DNAs was established and was used for developing SNPs and estimating minor allele frequencies (MAF). The sensitivity of the pooled DNA method for successfully detecting an SNP with an MAF >0.01 listed in the database was approximately 0.7; it was particularly efficient for detecting SNPs with MAF >0.1, which is compatible with the common disease/common variant hypothesis. The mean difference between the estimated and the observed MAFs was 0.03 +/- 0.023. The pooled DNA method identified four additional SNPs, for which the allele frequency information was not available in the database. The pooled DNA method is a cost- and time-effective tool for both qualifying and quantifying SNPs with considerable accuracy, and it can be particularly useful for dissecting the common disease/common variant hypothesis; this represents a best-case scenario for large-scale association mapping.

Positive and negative life events after counselling and testing: the Voluntary HIV-1 Counselling and Testing Efficacy Study.

INTRODUCTION: The results of the Voluntary HIV-1 Counselling and Testing Efficacy Study support the efficacy and cost-effectiveness of HIV voluntary counselling and testing (VCT) for reducing risk behaviors in three developing countries. METHODS: This report explores the social consequences of HIV VCT by examining the incidence of positive and negative life events at the first follow-up (an average of 7.3 months after recruitment). The incidence of positive and negative life events was compared between: (i) those who were randomly assigned to HIV VCT versus health information (HI); (ii) those who tested seronegative and those who tested seropositive; and (iii) those who disclosed their serostatus and those who did not. RESULTS: The occurrence of most negative life events was rare (0--4%); positive life events were more common (17--39%). With few exceptions, those assigned to HIV VCT were no more likely to experience negative life events than those who were assigned to HI. For individuals, positive serostatus was associated with increased support from health professionals, the break-up of a marriage and being neglected or disowned by their family. Serodiscordant couples with an HIV-positive woman were most likely to report the break-up of a marriage (20 versus 0--7% for other groups) and the break-up of a sexual relationship (45 versus 22--38% for other groups). Disclosure was associated with strengthening of a sexual relationship except for HIV-seropositive women. CONCLUSION: These findings, in combination with findings supporting the efficacy and cost-effectiveness of HIV VCT, support the dissemination of HIV VCT with appropriate support services in developing countries.

Response of Bacillus subtilis to cerulenin and acquisition of resistance.

Cerulenin is a fungal mycotoxin that potently inhibits fatty acid synthesis by covalent modification of the active site thiol of the chain-elongation subtypes of beta-ketoacyl-acyl carrier protein (ACP) synthases. The Bacillus subtilis fabF (yjaY) gene (fabF(b)) encodes an enzyme that catalyzes the condensation of malonyl-ACP with acyl-ACP to extend the growing acyl chain by two carbons. There were two mechanisms by which B. subtilis adapted to exposure to this antibiotic. First, reporter gene analysis demonstrated that transcription of the operon containing the fabF gene increased eightfold in response to a cerulenin challenge. This response was selective for the inhibition of fatty acid synthesis, since triclosan, an inhibitor of enoyl-ACP reductase, triggered an increase in fabF reporter gene expression while nalidixic acid did not. Second, spontaneous mutants arose that exhibited a 10-fold increase in the MIC of cerulenin. The mutation mapped at the B. subtilis fabF locus, and sequence analysis of the mutant fabF allele showed that a single base change resulted in the synthesis of FabF(b)[I108F]. The purified FabF(b) and FabF(b)[I108F] proteins had similar specific activities with myristoyl-ACP as the substrate. FabF(b) exhibited a 50% inhibitory concentration (IC(50)) of cerulenin of 0.1 microM, whereas the IC(50) for FabF(b)[I108] was 50-fold higher (5 microM). These biochemical data explain the absence of an overt growth defect coupled with the cerulenin resistance phenotype of the mutant strain.

Methotrexate bioavailability after oral and intramuscular administration in children.

Although methotrexate is one of the most commonly used drugs for maintenance therapy in childhood acute lymphocytic leukemia (ALL), its oral absorption is highly variable and its intramuscular bioavailability at dosages used for ALL therapy has not been assessed in children. We therefore determined the absolute bioavailability of orally and intramuscularly administered methotrexate in 12 pediatric patients receiving 13 to 120 mg/m2 methotrexate every week as maintenance therapy for ALL. Mean bioavailability, as determined by comparing the area under the concentration-time curve after oral or intramuscular administration with that produced by the same dosage given intravenously, was 33% (range 13% to 76%) for oral (n = 11) and 76% (54% to 112%) for intramuscular (n = 7) administration (P less than 0.01). Median bioavailability (with orally administered dosages less than or equal to 40 mg/m2 (range 13 to 40 mg/m2) was 42% (19% to 76%); at dosages greater than 40 mg/m2 (43 to 76 mg/m2), bioavailability was significantly lower, 17.5% (12.7% to 22.3%, p less than 0.02). Conversely, there was no significant relationship between dosage and bioavailability with intramuscularly administered drug. The substantially higher bioavailability for intramuscularly injected methotrexate may warrant its consideration as an alternative to oral administration, especially for dosages greater than 40 mg/m2.

Chromosome aberrations among the Yanomamma Indians.

The chromosomes of leucocytes cultured from the peripheral blood of 49 primitive Yanomama Indians of Venezuela were studied to determine the types and frequencies of aberrations in a human population not exposed to the same exogenous agents as civilized man. In all but one instance, 100 cells per individual were scored. In 13 cases, we found one or more cells with multiple complex breaks and rearrangements, represented by tetracentric, tricentric, and numerous dicentric chromosomes. From the standpoint of chromosomal damage, these cells are among the most abnormal cells yet described in vivo in man, and were not seen in the controls. There was also a higher than expected frequency of cells with an isolated structural aberration in both Indians and controls. This may be the result of a 24- to 48-hour delay in the initiation of culture. The cause of the more extensive damage to some cells remains to be determined.