Studies on filariasis VII : Histological observation on the encapsulated Brugia malayi larvae in the abdominal haemocoel of the mosquitoes, Armigeres subalbatus

Kobayashi, Mutsuo; Ogura, Nobuo; Tsuruoka, Hitomi; Chigusa, Yuichi; Mishima, Shogi

doi:10.7601/mez.37.59

Cited by 12 publications

(5 citation statements)

References 3 publications

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“…Three‐day‐old adult female Armigeres subalbatus were used because Kobayashi et al . (1986) demonstrated that nearly 95% of Dirofilaria immitis microfilariae (mf) inoculated into this mosquito species are melanized.…”

Section: Methodsmentioning

confidence: 99%

“…Mosquitoes Three-day-old adult female Armigeres subalbatus were used because Kobayashi et al (1986) demonstrated that nearly 95% of Dirofilaria immitis microfilariae (mf) inoculated into this mosquito species are melanized. Furthermore, Christensen et al (1986) demonstrated that parasite melanization by mosquitoes is related to age, and younger mosquitoes have a better parasite melanization ability.…”

Section: Methodsmentioning

confidence: 99%

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The use of a double subgenomic Sindbis virus expression system to study mosquito gene function: effects of antisense nucleotide number and duration of viral infection on gene silencing efficiency

Tamang¹,

Tseng²,

Huang³

et al. 2004

Insect Molecular Biology

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Recently we established a simple, effective antisense strategy using a double subgenomic Sindbis (dsSIN) virus expression system to study gene function in mosquitoes. In this study, we further elucidate the effects of antisense nucleotide number and duration of viral infection on mosquito gene silencing efficiency by the dsSIN virus expression system. Over 15 days post virus infection, the degree of parasite melanization was progressively reduced by more than 95%, 75% and 55% in the mosquito Armigeres subalbatus transduced with 600, 147 or 36 bases antisense RNA, targeted to the highly conserved copper binding region of the Ar. subalbatus prophenoloxidase I gene (As-pro-POI), respectively. As the duration of viral infection increased from day 3-15, the degree of parasite melanization progressively decreased in all mosquitoes transduced with antisense RNA, irrespective of the lengths of antisense RNA. Progressive loss of parasite melanization function was found to correlate with down regulation of As-pro-PO expression at both the mRNA and protein activity levels, and reductions in virus titres in mosquitoes transduced with antisense RNA. A small pro-PO RNA (c. twenty-five nucleotides) was identified in mosquitoes transduced with antisense RNA. These data suggest that As-pro-POI gene expression is knocked down by degrading the As-pro-POI mRNA through the RNAi pathway. In conclusion, our study demonstrates that even a short antisense RNA (thirty-six bases) can cause silencing of the As-pro-POI gene, and the effects of endogenous gene silencing by dsSIN expression system on mosquito gene functions can be accumulative.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

The use of a double subgenomic Sindbis virus expression system to study mosquito gene function: effects of antisense nucleotide number and duration of viral infection on gene silencing efficiency

Tamang¹,

Tseng²,

Huang³

et al. 2004

Insect Molecular Biology

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“…Armigeres subalbatus were obtained from the Center of Disease Control, Taipei, Taiwan, and have been kept in the insectary there since 1992. Microfilariae were obtained from dogs experimentally infected with Dirofilaria immitis, isolated from the blood by membrane filtration, and intrathoracically inoculated as previously described (Kobayashi et al, 1986;Liu et al, 1997).…”

Section: Mosquitoes and Filarial Wormsmentioning

confidence: 99%

Role of dopachrome conversion enzyme in the melanization of filarial worms in mosquitoes

Huang¹,

Christensen

Chen³

2005

Insect Molecular Biology

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Melanization is an effective defence reaction of mosquito hosts against invading parasites. In mosquitoes, the biosynthesis of melanin is initiated by the hydroxylation of tyrosine to DOPA by phenoloxidase (PO). DOPA is a branch point of the melanization reaction; it may be oxidized to dopaquinone by PO or be decarboxylated to dopamine by dopa decarboxylase. Further oxidation of dopaquinone by PO produces dopachrome. Dopachrome is then converted to 5, 6-dihydroxyindole by dopachrome conversion enzyme (DCE) to produce melanin. The conversion of dopachrome is a rate-limiting step of the melanization reaction, and the presence of PO and DCE significantly accelerates melanization reactions. In this study, a cDNA encoding DCE was cloned from the mosquito Armigeres subalbatus. Real-time PCR analysis revealed increased transcripts from haemocytes in microfilariae (mf)-inoculated mosquitoes. Gene silencing using double-stranded RNA was used to elucidate the role of DCE in the melanization reaction of parasites in Ar. subalbatus. The levels of both DCE transcripts and protein in gene knockdown mosquitoes were dramatically reduced. Compared with controls, the degree of melanization of mf in DCE-knockdown mosquitoes was significantly decreased. These results suggest that DCE is a critical enzyme that is required for effective melanization immune responses.

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“…subalbatus rapidly induces a melanization defense response and destroys naturally invading Brugia malayi microfilariae, but is permissive to the complete development of the closely related parasite, Brugia pahangi (Kobayashi et al, 1986;Beerntsen et al, 1989;Zhao et al, 1995). This mosquito species also kills, by melanotic encapsulation, 95% of Dirofilaria immitis microfilariae by melanotic encapsulation within 2 days following intrathoracic inoculation (Christensen et al, 1984).…”

Section: Introductionmentioning

confidence: 96%

The dual roles of Armigeres subalbatus prophenoloxidase V in parasite melanization and egg chorion melanization in the mosquito Ar. subalbatus

Tsao¹,

Chen²,

Li³

et al. 2015

Insect Biochemistry and Molecular Biology

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Studies on filariasis VII : Histological observation on the encapsulated Brugia malayi larvae in the abdominal haemocoel of the mosquitoes, Armigeres subalbatus

Abstract: The JapanSociety

Cited by 12 publications

References 3 publications

The use of a double subgenomic Sindbis virus expression system to study mosquito gene function: effects of antisense nucleotide number and duration of viral infection on gene silencing efficiency

The use of a double subgenomic Sindbis virus expression system to study mosquito gene function: effects of antisense nucleotide number and duration of viral infection on gene silencing efficiency

Role of dopachrome conversion enzyme in the melanization of filarial worms in mosquitoes

The dual roles of Armigeres subalbatus prophenoloxidase V in parasite melanization and egg chorion melanization in the mosquito Ar. subalbatus

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