Sequence Analysis of Mitochondrial Genome of Toxascaris leonina from a South China Tiger

Toxascaris leonina is a common parasitic nematode of wild mammals and has significant impacts on the protection of rare wild animals. To analyze population genetic characteristics of T. leonina from South China tiger, its mitochondrial (mt) genome was sequenced. Its complete circular mt genome was 14,277 bp in length, including 12 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and 2 non-coding regions. The nucleotide composition was biased toward A and T. The most common start codon and stop codon were TTG and TAG, and 4 genes ended with an incomplete stop codon. There were 13 intergenic regions ranging 1 to 10 bp in size. Phylogenetically, T. leonina from a South China tiger was close to canine T. leonina. This study reports for the first time a complete mt genome sequence of T. leonina from the South China tiger, and provides a scientific basis for studying the genetic diversity of nematodes between different hosts.

Effect of primarily cultured human lung cancer-associated fibroblasts on radiosensitivity of lung cancer cells / 中华放射肿瘤学杂志

Objective To investigate the effect of human lung cancer-associated fibroblasts (CAF) on the radiosensitivity of lung cancer cells when CAF is placed in direct contact co-culture with lung cancer cells.Methods Human lung CAF was obtained from fresh human lung adenocarcinoma tissue specimens by primary culture and subculture and was then identified by immunofluorescence staining.The CAF was placed in direct contact co-culture with lung cancer A549 and H1299 cells,and the effects of CAF on the radiosensitivity of A549 and H1299 cells were evaluated by colony-forming assay.Results The human lung CAF obtained by adherent culture could stably grow and proliferate,and it had specific expression of α-smooth muscle actin,vimentin,and fibroblast activation protein,but without expression of cytokeratin-18.The plating efficiency (PE,％) of A549 cells at 0 Gy irradiation was (20.0 ± 3.9) ％ when cultured alone versus (32.3 ± 5.5) ％ when co-cultured with CAF (t =3.16,P ＜ 0.05),and the PE of H1299 cells at 0 Gy irradiation was (20.6 ± 3.1) ％ when cultured alone versus (35.2 ± 2.3) ％ when co-cultured with CAF (t =6.55,P ＜0.05).The cell survival rate at 2 Gy irradiation (SF2) of A549 cells was 0.727 ±0.061 when cultured alone versus 0.782 ± 0.089 when co-cultured with CAF (t =0.88,P ＞ 0.05),and the SF2 of H1299 cells was 0.692 ±0.065 when cultured alone versus 0.782 ± 0.037 when co-cultured with CAF (t =2.08,P ＞0.05).The protection enhancement ratios of human lung CAF for A549 cells and H1299 cells were 1.29 and 1.25,respectively.Conclusions Human lung CAF reduces the radiosensitivity of lung cancer cells when placed in direct contact co-culture with them,and the radioprotective effect may be attributed to CAF promoting the proliferation of lung cancer cells.