The Genetic Diversity of Bactrocera dorsalis (Diptera: Tephritidae) in China and Neighboring Countries: A Review From Published Studies

For more than a decade, various research groups have tracked the population genetics of the oriental fruit fly, Bactrocera dorsalis (Hendel) in China and neighboring countries using mitochondrial cytochrome c oxidase subunit I (COI) DNA. Although most research has reported high levels of mtDNA variation, to date no efforts have been made to integrate and compare the results from these studies simultaneously. Here, we show that: 1) despite the fact that a large portion of the sampling effort has focused on the Yunnan province beginning in 2005, each subsequent study recovers only a small number of previously sampled haplotypes; 2) new haplotypes of B. dorsalis remain to be found, a projection of new haplotypes versus the number of individuals sampled suggest that sampling the species mtDNA diversity is far from reaching an asymptote; 3) it is unlikely that the observed genetic variation is the result of NUMTs (nuclear mitochondrial DNA), as most differences between haplotypes are silent substitutions; and 4) although all studies employed the 3′ end of COI, the length of COI fragment sequenced differs among studies, making comparisons challenging. Therefore, we offer these results with the caveat that mtDNA diversity might be underestimated in China.

Absence of Somatically Acquired JAK1 Mutations in Adult T-Cell Leukemia/Lymphoma.

Abstract 1921 Poster Board I-944 Background: Janus kinase 1 (JAK1) plays a critical role in lymphocyte proliferation and differentiation. Somatic JAK1 mutations are found in 18% of adult precursor T acute lymphoblastic leukemias (T-ALL). Some of the mutations were shown to induce the phosphorylation of JAK1 and STAT5 and lead to cytokine-independent proliferation. These data suggest that dysregulation of JAK1 can be involved in the development or progression of T-ALL (Flex et al. J Exp Med. 2008;205:751-758). Adult T-cell leukemia/lymphoma (ATLL) is a type of T-cell neoplasm, and the activation of JAK/STAT is sometimes observed in the tumor cells. Therefore, we investigated JAK1 mutations in ATLL patients. Patients and methods: Twenty Japanese ATLL patients whose percentage of peripheral abnormal lymphocytes was greater than 30% total cell count were sequentially enrolled into the study from 2000 to 2007. Diagnosis of ATLL was made on the basis of clinical features and laboratory characteristics. All cases tested positive for the serum anti-HTLV-1 antibody. The diagnosis was confirmed by observing monoclonal insertion of the HTLV-1 viral genome into leukemia cells by Southern blot hybridization. Peripheral blood mononuclear cells (PBMCs) were isolated and cryopreserved at -80°C. These PBMCs were thawed and genomic DNA was isolated using standard protocol. The entire coding sequence of the JAK1 gene (exons 2 through 25) was amplified by the polymerase chain reaction (PCR) method. The sequence of PCR primers were kindly provided by Dr. Marco Tartaglia (Istituto Superiore di Sanità, Roma, PhD). The nucleotide sequences were determined by fluorescent dye chemistry sequencing and analyzed by sequencing analysis software. By referencing the assembled sequence in the Ensembl genome database, the presence of homozygous mutations was first checked and then candidates for heterozygous mutations or single nucleotide polypeptides (SNPs) on each allele were screened by comparing the ratio of different bases calculated with the height of the peaks seen from sequencing to the reference genome when the ratio was between 0.15 and 1.0. Result: The percentage of abnormal lymphocytes ranged from 30-90%, and the mean value was 55.4%. The mean value of WBC and lymphocyte number was 40.5×109/L and 33.4×109/L, respectively. The mean value of LDH, Ca2+ or sIL-2R was 609 IU/L, 11.4 mg/dL, or 54748 U/mL, respectively. According to Shimoyama criteria (Shimoyama et al. Br J Haematol. 1991;79:428-437), 19 cases were diagnosed as acute-type ATLL, and one case was diagnosed as chronic-type ATLL. The surface markers of all but one abnormal PBMC were CD3+CD4+CD8-CD25+. In that one exception, loss of CD4 expression was observed. We examined the entire coding sequence of the JAK1 gene in 20 ATLL patients and identified no nonsynonymous or nonsense mutations and five types of silent substitutions in 12 cases. All silent substitutions were synonymous SNPs, as determined from referencing the base sequence in the Ensembl genome database. In the ATLL patients examined, the genotype frequency (%) is c546-AA/AG/GG, 97.5/2.5/0; c1590-CC/CT/TT, 97.5/2.5/0; c2049-CC/CT/TT, 50/50/0; c2097-CC/CG/GG, 95/5/0; c2199-AA/AG/GG, 60/40/0. There is no statistical difference in genotype frequency pattern of these SNPs, between the Japanese ATLL patients examined and the general Asian population on the Ensembl database. Conclusion: Mutations in the coding region of JAK1 do not associate with either activation of the JAK/STAT pathway or leukemogenesis in ATLL. We only examined the coding region of JAK1, and the regulatory region of JAK1 remains to be investigated. Further investigation including downstream signaling molecules and inhibitory molecules in the JAK/STAT signaling pathway is necessary to clarify the mechanism contributing to the leukemogenesis of ATLL. Disclosures: No relevant conflicts of interest to declare.

Nucleotide and Amino Acid Polymorphisms at Drug Resistance Sites in Non-B-Subtype Variants of Human Immunodeficiency Virus Type 1

ABSTRACT We have compared nucleotide substitutions and polymorphisms at codons known to confer drug resistance in subtype B strains of human immunodeficiency virus type 1 (HIV-1) with similar substitutions in viruses of other subtypes. Genotypic analysis was performed on viruses from untreated individuals. Nucleotide and amino acid diversity at resistance sites was compared with a consensus subtype B reference virus. Among patients with non-subtype B infections, polymorphisms relative to subtype B were observed at codon 10 in protease (PR). These included silent substitutions (CTC→CTT, CTA, TTA) and an amino acid mutation, L10I. Subtype A viruses possessed a V179I substitution in reverse transcriptase (RT). Subtype G viruses were identified by silent substitutions at codon 181 in RT (TAT→TAC). Similarly, subtype A/G viruses were identified by a substitution at position 67 in RT (GAC→GAT). Subtype C was distinguished by silent substitutions at codons 106 (GTA→GTG) and 219 (AAA→AAG) in RT and codon 48 (GGG→GGA) in PR. Variations relative to subtype B were seen at RT position 215 (ACC→ACT) for subtypes A and A/E. These substitutions and polymorphisms reflect different patterns of codon usage among viruses of different subtypes. However, the existence of different subtypes may only rarely affect patterns of drug resistance-associated mutations.