Dissertation > Excellent graduate degree dissertation topics show

The Endocrine Mechanism of Wing Morph Determination in Brown Planthopper, Nilaparvata Lugens (St(?)l)

Author: LiuShuHua
Tutor: LiuZeWen
School: Nanjing Agricultural College
Course: Agricultural Entomology and Pest Control
Keywords: Nilaparvata lugens (St(?)l) wing form differentiation endocrine mechanism Juvenile Hormone Esterase farnesoic acid O-methyltransferase CYP303A1
CLC: S435.112.3
Type: Master's thesis
Year: 2009
Downloads: 34
Quote: 0
Read: Download Dissertation

Abstract


Nilaparvata lugens (Stal) (Brown planthopper, BPH) is an important rice pest with the macropterous and brachypterous wing forms. The long wing morph can fly for a long range, and the short wing morph is not flight-capable. Although there are many factors which can affect the wing determination of BPH, JH titer might be a key factor.In order to monitor and manage the BPH, full-length cDNAs encoding JHE (Juvenile hormone esterase). FAMeT (Farnesoic acid O-methyltransferase) and CYP303A1 (Cytochrome P450 303A1) were cloned from BPH. All these three enzymes play important roles in biosynthetic or metabolism pathway of JH. The transcript levels of these three enzymes were detected in different development phases. And the transcript levels were compared between long wing strain and short wing strain. Some valuable breakthroughs had been achieved, which can promote the study of wing form differentiation in insects.1. Molecular cloning and characterization of Juvenile Hormone Esterase gene from BPHWe obtained a full-length cDNA encoding JHE in BPH (NlJHE) by RT-PCR and RACE technology. NlJHE is the first JHE cloned from the hemipteran insects. The deduced protein sequence of NlJHE contains the five conserved regions in JHEs of other insect species. NlJHE showed high amino acid similarities with Athalia rosae JHE (40%) and Apis mellifera JHE (39%). Recombinant NlJHE protein expressed in the baculovirus expression system hydrolyzed [3H] JH III at high activity and yielded the specificity constants (kcat/KM=4.28×106 M-1s-1) close to those of the validated JHEs from other insect species, indicating that NlJHE cDNA encodes a functional JH esterase. The NlJHE transcript was expressed mainly in the fat body and the expression levels reached a peak at 48 h after the molting of the 5th instar nymphs. In 5th instar, the macropterous showed significantly higher NlJHE mRNA levels and JHE activities than the brachypterous at early (just molting) and later (after 48 h from the molting) stages. These data suggest that NlJHE might play important roles in regulation of JH levels and wing form differentiation.2. Molecular cloning and characterization of farnesoic acid O-methyltransferase gene from BPHFarnesoic acid O-methyltransferase (FAMeT) is thought to be an important enzyme in the JH biosynthetic pathway, catalyzing methylation of farnesoic acid (FA) to methyl farnesoate (MF). A full-length cDNA (NlFAMeT) encoding a 299 amino acid putative FAMeT was isolated from BPH. NlFAMeT showed high amino acid identities (52-54%) with other insect FAMeTs. Although NlFAMeT transcript was expressed highly in corpus allatum (CA) and brain (without CA), no correlation was found between NlFAMeT transcript and JH titers. Low level of NlFAMeT transcript was detected in ovary, and NlFAMeT transcript had a positive change during the vitellogenesis in female adults. These data indicated that NlFAMeT might not be a key enzyme in JH synthesis in BPH, but play an important role in the ovary development.3. Molecular cloning and characterization of a corpora allata specific P450 CYP303A1 gene from BPHA new cytochrome P450, CYP303A1, was successfully cloned in BPH. Its full-length cDNA encoded a 497-aa protein that showed high identities with other insect P450 CYP303A1. The deduced protein has all features of a typical microsomal P450. CYP303A1 metabolizes methyl farnesoate to JH III. CYP303A1 gene is expressed selectively in the corpora allata (CA) of BPH. In 3rd-5th instar, the key stages for wing formation differentiation, CYP303A1 transcript levels, as well as JH titers, in brachypterous insects were significantly higher than those in macropterous insects. These data indicate that CYP303A1 is a key factor in regulating JH titer and consequential in regulating wing formation differentiation of BPH.Obviously, the mechanism of wing form differentiation in insects is complex, and JH titer is one of key factors. In this study, we investigate the endocrine mechanism by analyzing key enzymes in biosynthetic or metabolism pathway of JH. We cloned NlJHE cDNA, which is the first one cloned from the hemipteran insects. Moreover, a new cytochrome P450, CYP303A1, was also successfully cloned in BPH. All the research fruits can promote the study of wing form differentiation in insects. It provide some theory basis for monitoring and management of this pest.

Related Dissertations

  1. The Study of Protection and Its Mechanism That SB on Gastric and Intestinal Function from Combined Radiation and Burn Injury in Rat,R641
  2. Study on Host-Searching Behavior and Hosts Hormone Regulation of Trichogramma Spp,S476
  3. VOLATILES MEDIATED INTRA-AND INTERSPECIFIC INTERACTIONS AMONG RICE PLANTHOPPERS AND THEIR NATURAL ENEMIES,S476
  4. Imidacloprid Resistance and Its Mechanisms in Field Populations of Brown Planthopper, Nilaparvata Lugens (St(?)l),S433:3
  5. Characterization of Two Trehalases in Nilaparvata Lugens (St(?)l) and the Inhibitory Effect of Xenobiotics Against Trehalase,S433.3
  6. Case Study: Atmospheric Background for Great Immigration Events of the Brown Planthopper(Nilaparvata Lugens St(?)l),S435.112.3
  7. Studies on Mechanism of Physiology and Biochemistry and Resistance Responses of Different Rice Varieties to Nilaparvata Lugen(St(?)l),S511
  8. Studies on Nilaparvata Lugens (St(?)l) Populations with Different Virulence by Use of EPG and 2d-page Technology,S435.112.3
  9. Analysis of Gut Bacteria Diversity from Rice Planthoppers,S435.112.3
  10. Monitoring of Insecticide Resistance and Resistance Risk Assessment for JS118 in the Rice Stem Borer, Chilo Suppressalis (Walker),S435.112.1
  11. Researches on Developmental Characteristics of the Pink Rice Borer, Sesamia Inferens, on Differernt Host Plants and Insecticides for Controlling the Borer,S435.112.1
  12. Using an F2 Screen to Estimate the Frequency of Resistance Alleles to Cry1Ab in Wenzhou Population of Chilo Suppressalis and Cloning of an Aminopeptidase N Gene CsAPN3,S435.112.1
  13. Monitoring of Insecticide Resistance, Resistance Risk Assessment and Biochemical Mechanism for Buprofezin in Nilaparvata Lugens(St(?)l),S435.112.3
  14. Using an F2 Screen to Estimate the Frequency of Resistance Alleles to Cry1Ab in Wenzhou Population of Chilo Suppressalis and Cloning of an Aminopeptidase N Gene CsAPN3,S435.112.1
  15. Studies on the Differences of Tolerance between Chilo Supperssalis Walker and Sesamia Inferens Walker to Bt Rice,S435.112.1
  16. Study on the Occurrence Regularity and Migratory Biology of White-Baked Planthopper Sogatella Furcifera (Horváth),S435.112.3
  17. The DNA Cloning and RNA Interference of Some Functional Genes in Laodelphax Striatellus (Fallen),S435.112.3
  18. Replace highly toxic pesticides to control rice stem borer technology research,S435.112.1
  19. The Resistance Monitoring of Chilo Supprressalis (Walker) in Different Areas of Hunan Province,S435.112.1
  20. Studies on Control Techniques for First Generation of Chilo Suppressalis in Single Cropping Rice Region,S435.112.1
  21. Studies on Nilaparvata Lugens (St(?)l) Populations with Different Virulence by Use of EPG and 2d-page Technology,S435.112.3

CLC: > Agricultural Sciences > Plant Protection > Pest and Disease Control > Crop pests and diseases and their prevention > Cereal crop pests and diseases > Rice pests and diseases > Insect pest > Planthopper
© 2012 www.DissertationTopic.Net  Mobile