No abstract

BackgroundDouble minute chromosomes (DMs) are the cytogenetic hallmark of extra-chromosomal genomic amplification. They can well represent the advanced stage of malignancy. However, the mechanisms of DM generation are still not fully understood. Here, the sister chromatid exchange (SCE) was used to determine whether the occurrence of DMs was related to the high genomic instability in human carcinoma cells. We analyzed SCE frequencies in two groups of cell lines: the first group contained DM-positive cell lines such as UACC-1598, SK-PN-DW, and NCI-N87 carcinomas, while the second group comprised DM-negative cell lines including HO-8910, U251, and MGC-803.ResultsThe data showed that SCE was significantly increased in the DM-positive cells as compared to the DM-negative cells. In addition, there was a positive correlation between the incidence of DMs and the SCE frequency in the UACC-1598, SK-PN-DW, and NCI-N87 carcinoma cells.ConclusionsBecause SCE can reflect general genome instability, it is suggested that the DMs are likely to be closely associated with genomic instability in carcinoma cells. Meanwhile, SCE may be involved in the malignant progression of DM-positive cancers.

In this study, the whole mitochondrial genome of Elaphe schrenckii (Squamata: Colubridae) is first sequenced. It is a circular molecule of 17,165 bp in size and consists of 13 protein-coding genes, 22 transfer RNA (tRNA) genes, 2 ribosomal RNA (rRNA) genes and 2 control regions (CRI and CRII). Except for eight tRNAs and ND6 gene, all other mitochondrial genes were encoded on the heavy strand (H strand). The gene order and orientation of E. schrenckii mitogenome are basically identical to that of other alethinophidian snakes. Mitochondrial genome analyses based on MP, ML and NJ yielded identical phylogenetic trees, indicating a close phylogenetic affinity of 12 species of Colubridae snakes. This study will facilitate the further research of the population genetics of this species and systematic analyses of the genus Elaphe.

Argopistes tsekooni is a leaf-mining pest on Oleaceae plants in China. The complete mitochondrial genome of A. tsekooni was sequenced and annotated. It had a total length of 16,552 bp, including 13 PCGs, 2 ribosomal RNAs, 22 tRNAs, and a 2020 bp long non-coding AT-rich region. With a total length of 11,140 bp, all 13 PCGs started with ATN, 9 PCGs terminated with TAA, 3 PCGs terminated with TAG, except that COX3 terminated with an incomplete stop codon T. Maximum-likelihood phylogenetic analysis showed that A. tsekooni was closely grouped with seven other Galerucinae species, which did not contradict the previous morphological and molecular classification. ARTICLE HISTORY