RESUMO
Sphingolipids and their metabolites have been implicated in viral infection and replication in mammal cells but how their metabolizing enzymes in the host are regulated by viruses remains largely unknown. Here we report the identification of 12 sphingolipid genes and their regulation by Rice stripe virus in the small brown planthopper (Laodelphax striatellus Fallén), a serious pest of rice throughout eastern Asia. According to protein sequence similarity, we identified 12 sphingolipid enzyme genes in L. striatellus. By comparing their mRNA levels in viruliferous versus nonviruliferous L. striatellus at different life stages by qPCR, we found that RSV infection upregulated six genes (LsCGT1, LsNAGA1, LsSGPP, LsSMPD4, LsSMS, and LsSPT) in most stages of L. striatellus Especially, four genes (LsCGT1, LsSMPD2, LsNAGA1, and LsSMS) and another three genes (LsNAGA1, LsSGPP, and LsSMS) were significantly upregulated in viruliferous third-instar and fourth-instar nymphs, respectively. HPLC-MS/MS results showed that RSV infection increased the levels of various ceramides, such as Cer18:0, Cer20:0, and Cer22:0 species, in third and fourth instar L. striatellus nymphs. Together, these results demonstrate that RSV infection alters the transcript levels of various sphingolipid enzymes and the contents of sphingolipids in L. striatellus, indicating that sphingolipids may be important for RSV infection or replication in L. striatellus.
Assuntos
Regulação da Expressão Gênica , Hemípteros/genética , Hemípteros/virologia , Proteínas de Insetos/genética , Esfingolipídeos/genética , Tenuivirus/fisiologia , Animais , Cromatografia Líquida de Alta Pressão , Feminino , Hemípteros/enzimologia , Hemípteros/metabolismo , Proteínas de Insetos/metabolismo , Masculino , Ninfa/enzimologia , Ninfa/genética , Ninfa/metabolismo , Ninfa/virologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Análise de Sequência de RNA , Esfingolipídeos/metabolismo , Espectrometria de Massas em TandemRESUMO
Three polysaccharide fractions were obtained from Citrus aurantium L. (CAL) by sequential extraction with cold water, hot water, and 1.0M NaOH, respectively. The fractions were denoted CALA, CALB, and CALC. Structural characterization was conducted by physicochemical property, FTIR, and SEM analyses. Antioxidant activities in vivo and in vitro were also evaluated. CALB, which showed the highest activity, was further isolated to afford four purified polysaccharides (CALB-1-4) by various ion exchange and gel-filtration chromatography. Meanwhile, the purified polysaccharides were subjected to composition analysis and screened by antioxidant activity in vitro. Among the four purified polysaccharides, CALB-3 had the highest antioxidant activity and its structure was analyzed by FTIR, SEM and AFM microscopy. Overall, these results indicated that polysaccharides from CAL had potential therapeutic applications in the medical and food industries because of their antioxidant activities.