Lu Fuping

Purification and characterization of a novel fibrinolytic enzyme from Rhizopus chinensis 12

A novel fibrinolytic enzyme from Rhizopus chinensis 12 was purified through ammonium sulfate precipitation, hydrophobic interaction, ionic exchange, and gel filtration chromatography. The purification protocol resulted in a 893-fold purification of the enzyme, with a final yield of 42.6%. The apparent molecular weight of the enzyme was 18.0 kDa, determined by sodium dodecylsulfate-polyacrylamide gel electrophoresis, and 16.6 kDa by gel filtration chromatography, which revealed a monomeric form of the enzyme. The isoelectric point of the enzyme estimated by isoelectric focusing electrophoresis was 8.5±0.1. The enzyme hydrolyzed fibrin. It cleaved the α, β, and γ chains of fibrinogen simultaneously, and it also hydrolyzed casein and N-succinyl-Ala-Ala-Pro-Phe-pNA. The enzyme had an optimal temperature of 45°C, and an optimal pH of 10.5. EDTA, PCMB, and PMSF inhibited the activity of the enzyme, and SBTI, Lys, TPCK, and Aprotinine had no obvious inhibition, which suggested that the activity center of the enzyme had hydrosulfuryl and metal. The first 12 amino acids of the N-terminal sequence of the enzyme were S-V-S-E-I-Q-L-M-H-N-L-G and had no homology with that of other fibrinolytic enzyme from other microbes.

Potential geographic distribution of the cassava green mite Mononychellus tanajoa in Hainan, China

The cassava green mite, Mononychellus tanajoa, has been recently recorded as a quarantine pest in Hainan, China. It heavily damaged cassava growth and has caused serious economic losses in some main cassava production areas. In order to effectively monitor and manage this pest, it is necessary to investigate its potential geographical distribution worldwide. In this study, we used the ecological niche models, maximum entropy (Maxent), based on the biological data and known distribution of M. tanajoa, and meteorological data from 1950 to 2000 years in WorldClim to predict the potential geographical distribution of M. tanajoa. The results suggested that the suitable areas for cassava green mite infestations were mainly restricted to west Hainan (Danzhou, western Changjiang, western Dongfang, and southeast Ledong), north Hainan (Lingao, eastern Chenmai and northern Haikou), east Hainan (northern Lingshui and southern Wanning) and south Hainan (southern Sanya). In addition, some counties of eastern Hainan were predicted to have low suitability or unsuitable areas (e.g. Wenchang and Qionghai). A jackknife test in Maxent showed that the temperature annual range was the most important environmental variable affecting the distribution of M. tanajoa. Consequently, the study suggests several reasonable regulations and management strategies for avoiding the introduction or invasion of this high-risk cassava pest to these potentially suitable areas.