| Xuepeng Cai | 5 Articles |
Chitinase AO-801 is a hydrolase secreted by Arthrobotrys oligospora during nematode feeding, while its role remained elusive. This study analyzed the molecular characteristics of recombinant chitinase of Arthrobotrys oligospora (reAO-801). AO-801 belongs to the typical glycoside hydrolase 18 family with conserved chitinase sequence and tertiary structure of (α/β)8 triose-phosphate isomerase (TIM) barrel. The molecular weight of reAO-801 was 42 kDa. reAO-801 effectively degraded colloidal and powdered chitin, egg lysate, and stage I larval lysate of Caenorhabditis elegans. The activity of reAO-801 reached its peak at 40˚C and pH values between 4-7. Enzyme activity was inhibited by Zn2+, Ca2+, and Fe3+, whereas Mg2+ and K+ potentiated its activity. In addition, urea, sodium dodecyl sulfate, and 2-mercaptoethanol significantly inhibited enzyme activity. reAO-801 showed complete nematicidal activity against C. elegans stage I larvae. reAO-801 broke down the C. elegans egg shells, causing them to die or die prematurely by hatching the eggs. It also invoked degradation of Haemonchus contortus eggs, resulting in apparent changes in the morphological structure. This study demonstrated the cytotoxic effect of reAO-801, which laid the foundation for further dissecting the mechanism of nematode infestation by A. oligospora.
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Cystatin, a cysteine protease inhibitor found in many parasites, plays important roles in immune evasion. This study analyzed the molecular characteristics of a cystatin from Fasciola hepatica (FhCystatin) and expressed recombinant FhCystatin (rFhcystatin) to investigate the immune modulatory effects on lipopolysaccharide-induced proliferation, migration, cytokine secretion, nitric oxide (NO) production, and apoptosis in mouse macrophages. The FhCystatin gene encoded 116 amino acids and contained a conserved cystatin-like domain. rFhCystatin significantly inhibited the activity of cathepsin B. rFhCystatin bound to the surface of mouse RAW264.7 cells, significantly inhibited cell proliferation and promoted apoptosis. Moreover, rFhCystatin inhibited the expression of cellular nitric oxide, interleukin-6, and tumor necrosis factor-α, and promoted the expression of transforming growth factor-β and interleukin-10. These results showed that FhCystatin played an important role in regulating the activity of mouse macrophages. Our findings provide new insights into mechanisms underlying the immune evasion and contribute to the exploration of potential targets for the development of new drug to control F. hepatica infection.
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We report here a human case of Taenia asiatica infection which was confirmed by genetic analyses in Dali, China. A patient was found to have symptoms of taeniasis with discharge of tapeworm proglottids. By sequencing of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene, we observed nucleotide sequence identity of 99% with T. asiatica and 96% with T. saginata. Using the cytochrome b (cytb) gene, 99% identity with T. asiatica and 96% identity with T. saginata were found. Our findings suggest that taeniasis of people in Dali, China may be mainly caused by T. asiatica.
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The tapeworm Taenia solium is an important human zoonotic parasite that causes great economic loss and also endangers public health. At present, an effective vaccine that will prevent infection and chemotherapy without any side effect remains to be developed. In this study, codon usage patterns in the T. solium genome were examined through 8,484 protein-coding genes. Neutrality analysis showed that T. solium had a narrow GC distribution, and a significant correlation was observed between GC12 and GC3. Examination of an NC (ENC vs GC3s)-plot showed a few genes on or close to the expected curve, but the majority of points with low-ENC (the effective number of codons) values were detected below the expected curve, suggesting that mutational bias plays a major role in shaping codon usage. The Parity Rule 2 plot (PR2) analysis showed that GC and AT were not used proportionally. We also identified 26 optimal codons in the T. solium genome, all of which ended with either a G or C residue. These optimal codons in the T. solium genome are likely consistent with tRNAs that are highly expressed in the cell, suggesting that mutational and translational selection forces are probably driving factors of codon usage bias in the T. solium genome.
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Wnt proteins are a family of secreted glycoproteins that are evolutionarily conserved and considered to be involved in extensive developmental processes in metazoan organisms. The characterization of Citations Citations to this article as recorded by
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