Selectional versus mutational mechanism underlying genomic features of bacterial strand asymmetry: a case study in Clostridium acetobutylicum.

Strand biases are widespread in bacterial genomes. In this review, we discuss 5 types of bias, including gene orientation, the number of open reading frames, nucleotide composition, substitution rate, and gene length, between leading and lagging strands during replication. For each type of strand bias, related studies were summarized and Clostridium acetobutylicum ATCC 824 was used as a representative example to illustrate bias. Our results in C. acetobutylicum indicate that there is little asymmetry between 2 replication strands on open reading frame number and gene length, whereas the other 3 features presented significant strand bias. The underlying mechanisms of mutation and/or selection are discussed. It is hoped that this review will improve the understanding of the extent and reasons for various types of strand bias in bacterial genomes.

The effect of aerobic exercise and Macrothele raven venom on tumor-bearing mice.

Liver cancer is one of the most common cancers in the world. Macrothele raven venom, a complicated mixture of neurotoxic peptides, proteins and low molecular weight material, has antitumor properties, but its mechanism of action is unknown. Moderate exercise has been shown to shrink tumors and cause a remarkable reduction in the tumor growth rate. In this study, we examined the antitumor effect of Macrothele raven venom in combination with exercise on tumor-bearing mice. Our results demonstrate that aerobic exercise in combination with venom administered at different doses was much more effective in a mouse H22 hepatoma model compared to separate administration of the 2 treatments. The underlying mechanism of this effect may be related to the expression of various tumor suppressor factors.