Mitochondrial analysis of oribatid mites provides insights into their atypical tRNA annotation, genome rearrangement and evolution.

BACKGROUND: The mitochondrial (mt) genomes of Sarcoptiformes mites typically contain 37 genes. Although the loss of genes is rare in Sarcoptiformes mite mitogenomes, two of the six previously reported oribatid mites (Acariforms: Sarcoptiformes) are reported to have lost parts of their tRNA genes. To confirm whether the tRNA genes were indeed lost and whether the loss is universal, we re-annotated the available oribatid mite sequences and sequenced the mitogenome of Oribatula sakamorii. METHODS: The mitogenome of O. sakamorii was sequenced using an Illumina HiSeq sequencer. The mt tRNA gene was annotated using multi-software combined with a manual annotation approach. Phylogenetic analyses were performed using the maximum likelihood and Bayesian inference methods with concatenated nucleotide and amino acid sequences. RESULTS: The mitogenomes of O. sakamorii contained 37 genes, including 22 tRNA genes. We identified all mt tRNA genes that were reported as "lost" in Steganacarus magnus and Paraleius leontonychus and revealed certain atypical tRNA annotation errors in oribatid mite sequences. Oribatid mite mitogenomes are characterized by low rates of genetic rearrangement, with six or seven gene blocks conserved between the mitogenome of all species and that of ancestral arthropods. Considering the relative order of the major genes (protein-coding genes and rRNAs), only one or two genes were rearranged with respect to their positions in the ancestral genome. We explored the phylogenetic relationships among the available oribatid mites, and the results confirmed the systematic position of Hermannia in the Crotonioidea superfamily. This was also supported by the synapomorphic gene-derived boundaries. CONCLUSIONS: The tRNA "lost" phenomenon is not universal in oribatid mites. Rather, highly atypical secondary structure of the inferred mt tRNA genes made them unidentifiable using a single type of tRNA search program. The use of multi-software combined with a manual annotation approach can improve the accuracy of tRNA gene annotation. In addition, we identified the precise systematic position of Hermannia and validated that Astigmata is nested in Oribatida.

[Effect of exercise on adiponectin in aged obese rats].

OBJECTIVE: To explore effects of exercise on the expression of adiponectin mRNA and protein in visceral adipose tissue, plasma adiponectin concentration, and insulin resistance of aged obese rats. METHODS: Male SD rats age to 21 days old were fed with high-fat diet (fat percentage was 36.3% to 40.0%) for three stages of adolescence, maturity and old age to establish elderly obesity rats model. When the rats aged to 60 weeks old, natural growing elderly rats were randomly divided into control group (C) and aged exercise group (AE), n=6; elderly obesity rats were randomly divided into obesity control group (OC) and obesity exercise group (OE), n=6. The treadmill grade was 0°, the exercise speed and time were 15 m/min×15 min, 4 groups each time, between consecutive groups the rats had 5 minutes rest, the rats were exercised for 60 minutes every day, five days a week, continuous exercise for 8 weeks. Then, the expressions of adiponectin mRNA and protein in visceral adipose tissue were determined. The concentrations of blood glucose, plasma adiponectin and insulin were measured. Insulin resistance was calculated. RESULTS: Comparison with control group, the expressions of adiponectin mRNA and protein were obviously decreased, the concentration of blood glucose and insulin resistance were significantly increased in obesity control group, while the expressions of adiponectin mRNA and protein were obviously increased. Comparison with obesity control group, the expressions of adiponectin mRNA and protein, the concentration of plasma adiponectin were obviously increased, the concentration of blood glucose and insulin resistance were significantly decreased in obesity exercise group. CONCLUSIONS: Adiponectin mRNA and protein expression in visceral adipose tissue is decreased and accompanied by high blood glucose and insulin resistance in elderly obesity rats. Exercise can increase the adiponectin mRNA and protein expression in visceral adipose tissue, elevate levels of plasma adiponectin, and decrease the level of blood glucose and insulin resistance in elderly obesity rats.