Wolbachia are maternally inherited endosymbiotic bacteria infecting a wide range of arthropods and filarial nematodes. They can induce various reproduction alterations in their hosts, including thelytokous parthenogen...Wolbachia are maternally inherited endosymbiotic bacteria infecting a wide range of arthropods and filarial nematodes. They can induce various reproduction alterations in their hosts, including thelytokous parthenogenesis, cytoplasmic incompatibility （CI）, feminization of genetic males and male killing. Here we investigated diversity and prevalence patterns of Wolbachia infection in 43 geographical populations of the Asian corn borer, Ostriniafurnacalis, in China and one population in North Korea. Based on Wolbachia surface protein gene （wsp） sequences, nine strains of Wolbachia （wFurl-wFur9）, belonging to supergroups A and B, were identified in populations of O. furnacalis with an average infection rate of 10.5%. Superinfection commonly appeared in individuals of O. furnacalis and coinfection patterns were very complex. There was no specific pattern for the prevalence and distribution of the nine Wolbachia strains suggesting an intricate evolutionary history of Wolbachia infection in this species. The genetic similarity of the wFurl-wFur9 strains with those detected in two parasitoids of O. furnacalis, Macrocentrus cingulum and Lydella grisescens, strongly suggests host-parasitoid horizontal transmission.展开更多
Chitinase catalyzes β,4-glycosidic linkages in chitin and has attracted re- search interest due to it being a potential pesticide target and an enzymatic tool for preparation of N-acetyl-β D-glucosamine. An individu...Chitinase catalyzes β,4-glycosidic linkages in chitin and has attracted re- search interest due to it being a potential pesticide target and an enzymatic tool for preparation of N-acetyl-β D-glucosamine. An individual insect contains multiple genes encoding chitinases, which vary in domain architectures, expression patterns, physiological roles and biochemical properties. Herein, Of ChtS, the glycoside hydrolase family 18 chiti- nase from the widespread lepidopteran pest Ostrinia furnacalis, was cloned, expressed in the yeast Pichia pastoris and biochemically characterized in an attempt to facilitate both pest control and biomaterial preparation. Complementary DNA sequence analysis indicated that Of CHT5 consisted of an open reading frame of 1 665-bp nucleotides. Phy- logenic analysis suggested Of Cht5 belongs to the Group I insect chitinases. Expression of Of Cht5 in Pichia pastoris resulted in highest specific activity after 120 h of induction with methanol. Through two steps of purification, consisting of ammonium sulfate pre- cipitation and metal chelating chromatography, about 7 mg of the recombinant Of Cht5 was purified to homogeneity from 1 L culture supernatant. Of Cht5 effectively converted colloidal chitin into chitobiose, but had relatively low activity toward a-chitin. When chi- tooligosaccharides [（GlcNAc）n, n = 3-6] were used as substrates, Of Cht5 was observed to possess the highest catalytic efficiency parameter toward （GlcNAc）4 and predominan- tely hydrolyzed the second glycosidic bond from the non-reducing end. Together with fl-N-acetyl-D-hexosaminidase OfHexl, Of Cht5 achieved its highest efficiency in chitin degradation that yielded N-acetyl-β D-glucosamine, a valuable pharmacological reagent and food supplement, within a molar concentration ratio of Of Cht5 versus Of Hexl in the range of 9 ： 1-15 ： 1. This work provides an alternative to existing preparation of chitinase for pesticides and other applications.展开更多
Asian corn borer, Ostrinia furnacalis （Guenee）, is a key corn pest in the Asian-Western Pacific countries. It overwinters as flail-grown larvae in plant stalks or in a spun-silk covering located in the plant debris ...Asian corn borer, Ostrinia furnacalis （Guenee）, is a key corn pest in the Asian-Western Pacific countries. It overwinters as flail-grown larvae in plant stalks or in a spun-silk covering located in the plant debris in the temperate regions of China. Supercooling point （SCP） and survival rate after low sub-zero temperature treatment were assessed for field-collected populations in the laboratory using a cool bath with a 1 ℃/min cooling rate until -40℃. Mean SCPs were varied among geographical populations, with a significant decline from -22.7℃ of Haikou, the multivoltine tropical population in the south, to -28.5℃ of Gongzhuling, the univoltine temperate population in the northeast of China. In addition, there was more than 1℃ difference in SCP between Gongzhuling univoltine and bivoltine populations that were from the same geographic origin. Mean SCPs of the Guangzhou population fluctuated over the year, with significantly lower SCPs in winter than in other seasons, which correlated with a significantly higher proportion of diapausing larvae in winter than in other seasons. Over 41% of overwintering larvae from the northeast population could withstand to be supercooled for a few minutes to the low sub-zero temperature of-40℃, but only 6.7% of their southern counterparts did so. The findings from this study suggest that O. furnacalis mostly takes advantage of freeze avoidance as diapausing larvae for overwintering in the southern region, whereas it exhibits freeze tolerance in diapause in the northeastern region.展开更多
基金funded by China Agriculture Research System(CARS-02)
文摘Wolbachia are maternally inherited endosymbiotic bacteria infecting a wide range of arthropods and filarial nematodes. They can induce various reproduction alterations in their hosts, including thelytokous parthenogenesis, cytoplasmic incompatibility （CI）, feminization of genetic males and male killing. Here we investigated diversity and prevalence patterns of Wolbachia infection in 43 geographical populations of the Asian corn borer, Ostriniafurnacalis, in China and one population in North Korea. Based on Wolbachia surface protein gene （wsp） sequences, nine strains of Wolbachia （wFurl-wFur9）, belonging to supergroups A and B, were identified in populations of O. furnacalis with an average infection rate of 10.5%. Superinfection commonly appeared in individuals of O. furnacalis and coinfection patterns were very complex. There was no specific pattern for the prevalence and distribution of the nine Wolbachia strains suggesting an intricate evolutionary history of Wolbachia infection in this species. The genetic similarity of the wFurl-wFur9 strains with those detected in two parasitoids of O. furnacalis, Macrocentrus cingulum and Lydella grisescens, strongly suggests host-parasitoid horizontal transmission.
文摘Chitinase catalyzes β,4-glycosidic linkages in chitin and has attracted re- search interest due to it being a potential pesticide target and an enzymatic tool for preparation of N-acetyl-β D-glucosamine. An individual insect contains multiple genes encoding chitinases, which vary in domain architectures, expression patterns, physiological roles and biochemical properties. Herein, Of ChtS, the glycoside hydrolase family 18 chiti- nase from the widespread lepidopteran pest Ostrinia furnacalis, was cloned, expressed in the yeast Pichia pastoris and biochemically characterized in an attempt to facilitate both pest control and biomaterial preparation. Complementary DNA sequence analysis indicated that Of CHT5 consisted of an open reading frame of 1 665-bp nucleotides. Phy- logenic analysis suggested Of Cht5 belongs to the Group I insect chitinases. Expression of Of Cht5 in Pichia pastoris resulted in highest specific activity after 120 h of induction with methanol. Through two steps of purification, consisting of ammonium sulfate pre- cipitation and metal chelating chromatography, about 7 mg of the recombinant Of Cht5 was purified to homogeneity from 1 L culture supernatant. Of Cht5 effectively converted colloidal chitin into chitobiose, but had relatively low activity toward a-chitin. When chi- tooligosaccharides [（GlcNAc）n, n = 3-6] were used as substrates, Of Cht5 was observed to possess the highest catalytic efficiency parameter toward （GlcNAc）4 and predominan- tely hydrolyzed the second glycosidic bond from the non-reducing end. Together with fl-N-acetyl-D-hexosaminidase OfHexl, Of Cht5 achieved its highest efficiency in chitin degradation that yielded N-acetyl-β D-glucosamine, a valuable pharmacological reagent and food supplement, within a molar concentration ratio of Of Cht5 versus Of Hexl in the range of 9 ： 1-15 ： 1. This work provides an alternative to existing preparation of chitinase for pesticides and other applications.
文摘Asian corn borer, Ostrinia furnacalis （Guenee）, is a key corn pest in the Asian-Western Pacific countries. It overwinters as flail-grown larvae in plant stalks or in a spun-silk covering located in the plant debris in the temperate regions of China. Supercooling point （SCP） and survival rate after low sub-zero temperature treatment were assessed for field-collected populations in the laboratory using a cool bath with a 1 ℃/min cooling rate until -40℃. Mean SCPs were varied among geographical populations, with a significant decline from -22.7℃ of Haikou, the multivoltine tropical population in the south, to -28.5℃ of Gongzhuling, the univoltine temperate population in the northeast of China. In addition, there was more than 1℃ difference in SCP between Gongzhuling univoltine and bivoltine populations that were from the same geographic origin. Mean SCPs of the Guangzhou population fluctuated over the year, with significantly lower SCPs in winter than in other seasons, which correlated with a significantly higher proportion of diapausing larvae in winter than in other seasons. Over 41% of overwintering larvae from the northeast population could withstand to be supercooled for a few minutes to the low sub-zero temperature of-40℃, but only 6.7% of their southern counterparts did so. The findings from this study suggest that O. furnacalis mostly takes advantage of freeze avoidance as diapausing larvae for overwintering in the southern region, whereas it exhibits freeze tolerance in diapause in the northeastern region.
