Genome-wide analysis of MYB family in Nicotiana benthamiana and the functional role of the key members in resistance to Bemisia tabaci.

MYB transcription factors (TFs) play a key role in plant resistance to abiotic and biotical stresses. However, little is currently known about their involvement in the plant defense to piercing-sucking insects. Here, we studied the MYB TFs that responded to and resisted Bemisia tabaci whitefly in the model plant Nicotiana benthamiana. Firstly, a total of 453 NbMYB TFs in N. benthamiana genome were identified and 182 R2R3-MYB TFs were analyzed for molecular characteristics, phylogenetic analysis, genetic structure, motif composition, and cis-elements. Then, six stress-related NbMYB genes were selected for further study. The expression pattern shows they were highly expressed in mature leaves and intensively induced upon whitefly attack. Combined with bioinformatic analysis, overexpression, ß-Glucuronidase (GUS) assay, and virus-induced silencing tests, we determined the transcriptional regulation of these NbMYBs on the genes in lignin biosynthesis and SA-signaling pathways. Meanwhile, we tested the performance of whitefly on plants with increased or silenced NbMYB genes expression and found that NbMYB42, NbMYB107, NbMYB163, and NbMYB423 were resistant to whitefly. Our results contribute to a comprehensive understanding of the MYB TFs in N. benthamiana. Furthermore, our findings will facilitate further studies on the role of MYB TFs in the interaction between plants and piercing-sucking insects.

Small RNA and Degradome Sequencing Reveal Important MicroRNA Function in Nicotiana tabacum Response to Bemisia tabaci.

MicroRNAs (miRNAs), a class of small non-coding regulatory RNAs, are key molecules in many biological and metabolic processes of plant growth, development and stress response via targeting mRNAs. The phloem-feeding insect whitefly Bemisia tabaci (Hemiptera, Aleyrodidae) is a serious pest that causes devastating harm to agricultural production worldwide. However, the function of host miRNAs in the response to whitefly infestation remains unclear. Here, we sequenced the small RNA and degradome of tobacco (Nicotiana tabacum L.), after and before infestation by B. tabaci. We identified 1291 miRNAs belonging to 138 miRNA families including 706 known miRNAs and 585 novel miRNAs. A total of 47 miRNAs were differentially expressed, of which 30 were upregulated and 17 were downregulated by whitefly exposure. Then, computational analysis showed that the target genes of differential miRNAs were involved in R gene regulation, plant innate immunity, plant pathogen defense, the plant hormone signal pathway and abiotic stress tolerance. Furthermore, degradome analysis demonstrated that 253 mRNAs were cleaved by 66 miRNAs. Among them, the targets cleaved by upregulated miR6025, miR160, miR171, miR166 and miR168 are consistent with our prediction, suggesting that pathogen-related miRNAs may function in plant defense against whitefly. Moreover, our results show that plant miRNA response and miRNA-mediated post-transcriptional regulation for phloem-feeding insect infestation are similar to pathogen invasion. Our study provides additional data to further elucidate how host plants respond and defend the phloem-feeding insects.

Effects of Kathon, a Chemical Used Widely as a Microbicide, on the Survival of Two Species of Mosquitoes.

In recent decades, demands for novel insecticides against mosquitoes are soaring, yet candidate chemicals with desirable properties are limited. Kathon is a broad-spectrum isothiazolinone microbicide, but other applications remain uncharacterized. First, we treated larvae of Culex quinquefasciatus and Aedes albopictus, two major mosquito vectors of human viral diseases, with Kathon at 15 mg/L (a concentration considered safe in cosmetic and body care products), and at lower concentrations, and found that Kathon treatment resulted in high mortality of larvae. Second, sublethal concentration of Kathon can cause significantly prolonged larval development of C. quinquefasciatus. Third, we explored the effects of two constituents of Kathon, chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT), on the survival of larvae, and found that CMIT was the major toxic component. Further, we explored the mechanisms of action of Kathon against insect cells and found that Kathon reduces cell viability and adenosine triphosphate production but promotes the release of lactate dehydrogenase in Drosophila melanogaster S2 cells. Our results indicate that Kathon is highly toxic to mosquito larvae, and we highlight its potential in the development of new larvicides for mosquito control.

Functional Analysis of Alkaline Phosphatase in Whitefly Bemisia tabaci (Middle East Asia Minor 1 and Mediterranean) on Different Host Plants.

Alkaline phosphatases (ALPs: EC 3.1.3.1) are ubiquitous enzymes and play crucial roles in the fundamental phosphate uptake and secretory processes. Although insects are regarded as the most diverse group of organisms, the current understanding of ALP roles in insects is limited. As one type of destructive agricultural pest, whitefly Bemisia tabaci, a phloem feeder and invasive species, can cause extensive crop damage through feeding and transmitting plant diseases. In this study, we retrieved five ALP genes in MEAM1 whitefly, nine ALP genes in MED whitefly via comparative genomics approaches. Compared with nine other insects, whiteflies' ALP gene family members did not undergo significant expansion during insect evolution, and whiteflies' ALP genes were dispersed. Moreover, whiteflies' ALP gene family was conserved among insects and emerged before speciation via phylogenetic analysis. Whiteflies' ALP gene expression profiles presented that most ALP genes have different expression patterns after feeding on cotton or tobacco plants. Female/male MED whiteflies possessed higher ALP activities on both cotton and tobacco plants irrespective of sex, relative to MEAM1 whiteflies. Meanwhile, adult MED whiteflies possessed higher ALP activity in both whole insect and salivary samples, relative to MEAM1 whiteflies. We also found that both MED and MEAM1 whiteflies could upregulate ALP activities after feeding on cotton compared with feeding on tobacco plants. These findings demonstrated the functions of whiteflies ALPs and will assist the further study of the genomic evolution of insect ALPs.

The molecular mechanisms that determine different degrees of polyphagy in the Bemisia tabaci species complex.

The whitefly Bemisia tabaci is a closely related group of >35 cryptic species that feed on the phloem sap of a broad range of host plants. Species in the complex differ in their host-range breadth, but the mechanisms involved remain poorly understood. We investigated, therefore, how six different B. tabaci species cope with the environmental unpredictability presented by a set of four common and novel host plants. Behavioral studies indicated large differences in performances on the four hosts and putative specialization of one of the species to cassava plants. Transcriptomic analyses revealed two main insights. First, a large set of genes involved in metabolism (>85%) showed differences in expression between the six species, and each species could be characterized by its own unique expression pattern of metabolic genes. However, within species, these genes were constitutively expressed, with a low level of environmental responsiveness (i.e., to host change). Second, within each species, sets of genes mainly associated with the super-pathways "environmental information processing" and "organismal systems" responded to the host switching events. These included genes encoding for proteins involved in sugar homeostasis, signal transduction, membrane transport, and immune, endocrine, sensory and digestive responses. Our findings suggested that the six B. tabaci species can be divided into four performance/transcriptomic "Types" and that polyphagy can be achieved in multiple ways. However, polyphagy level is determined by the specific identity of the metabolic genes/pathways that are enriched and overexpressed in each species (the species' individual metabolic "tool kit").

Protective effect of antioxidant on renal damage caused by doxorubicin chemotherapy in mice with hepatic cancer.

OBJECTIVES: To investigate the protective effects and mechanism of antioxidant TBHQ on renal damage caused by doxorubicin chemotherapy in mice with hepatic cancer. METHODS: Cell H22 of mice with hepatic cancer which was subcultured for three times was subcutaneously transplanted to the groin of right lower limb of 45 SPF Kunming mice to establish the transplanted tumor model. The doxorubicin chemotherapy group and antioxidant intervention group received intraperitoneal injection of ADM (1 mg/kg·0.2 mL/2 d). The model control group received normal saline (NS) of the same volume at the same time. 1% TBHQ was added into the diet of mice of the antioxidant intervention group. Seven weeks later, morning urines and peripheral blood were randomly collected to detect UAlb, UCr, BUN, Scr and UAlb/Cr levels. All mice were beheaded. The renal tissues were made into homogenate, and SOD, T-AOC and MDA content in tissues were detected followed by cell lysis. All data were processed using SPSS19.0. RESULTS: The UAlb/Cr, BUN, Scr and MDA of doxorubicin chemotherapy group were significantly higher those of model control group and the activities of SOD, T-AOC in doxorubicin chemotherapy group were lower than those of model control group (P < 0.01). The UAlb/Cr, BUN, Scr and MDA of antioxidant intervention group were lower than those of doxorubicin chemotherapy group and the activities of SOD, T-AOC of antioxidant intervention group were higher than those of doxorubicin chemotherapy group doxorubicin chemotherapy group (P < 0.05). The BUN of model control group was higher than that of blank group, and T-AOC was lower than that of blank group, and difference was statistically significant (P < 0.05). CONCLUSIONS: Doxorubicin chemotherapy could lead to abnormal antioxidant capacity and renal function of tumor-bearing mice with hepatic cancer. TBHQ antioxidant intervention could effectively improve the antioxidant capacity of renal tissue and reduce the renal damage caused by doxorubicin to some extent.

[The application of intraoperative ultrasonography in the diagnosis and therapy of insulinoma].

OBJECTIVE: To analyze the value of intraoperative ultrasonography (IOUS) in the diagnosis and therapy of insulinoma. METHODS: From January 2000 to December 2007, the application of intraoperative ultrasonography used in 44 cases with insulinoma who came from department of general surgery, First Affiliated Hospital of Zhengzhou University were retrospectively analyzed. There were 19 males and 25 females in the group. Every case accepted operation and examination of IOUS. RESULTS: Tumor was accurately located and its adjacent structure was also clear by IOUS in 43 cases, the other one was islet cell hyperplasia, the detection rate of tumor was 100%. The complications: one case occurred pancreatic fistula, one occurred pancreatitis, and there was no biliary fistula and hemorrhage. CONCLUSIONS: Presently, IOUS is one simple and effective method to local insulinoma, and it could improve the success rate of operation and reduce complications.