Differential vitellin polypeptide processing in insect embryos

Giorgi, Franco; Bradley, James T.; Nordin, John H.

doi:10.1016/s0968-4328(99)00054-2

Cited by 71 publications

(52 citation statements)

References 136 publications

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“…During embryogenesis, VTDCE is observed in a low MW form corresponding to a free enzyme, and several high molecular weight forms, which are also recognized by anti-Vt antibodies and correspond to VTDCE associated with different Vt subunits and/or Vt partial digestion products. This kind of association that alters the apparent molecular weight was previously described for other arthropod enzymes and could be related to Vt-degradation control (Giorgi et al 1999).…”

Section: Discussionsupporting

confidence: 60%

Localization and function ofRhipicephalus (Boophilus) microplusvitellin-degrading cysteine endopeptidase

et al. 2010

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S U M M A R YThe tick Rhipicephalus (Boophilus) microplus is an important parasite of cattle in many areas of the tropics. Characterization of molecules involved in mechanisms such as vitellogenesis and embryo development may contribute to a better understanding of this parasite's physiology. The vitellin-degrading cysteine endopeptidase (VTDCE) is the most active enzyme involved in vitellin hydrolysis in R. microplus eggs. Here we show an association between VTDCE and vitellin in an additional site, apart from the active site. Our data also demonstrate cysteine endopeptidase activity in different tissues such as ovary, gut, fat body, salivary gland and female haemolymph, where it is controlled by a physiological inhibitor. In R. microplus female gut, VTDCE is localized in areas of protein synthesis and trafficking with the underlying haemolymph. VTDCE is also localized in the ovary basal region, in vesicle membranes of ovary pedicel cells and in oocyte cytosol. These results suggest that VTDCE plays a role in vitellin digestion during tick development.

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Section: Discussionsupporting

confidence: 60%

Localization and function ofRhipicephalus (Boophilus) microplusvitellin-degrading cysteine endopeptidase

et al. 2010

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“…Insect vitellogenins are proteins synthesized mainly in the female fat body and released into the haemolymph (Tufail and Takeda, 2008;Azevedo et al, 2011), and are later transferred to oocytes via receptor-mediated endocytosis (Tufail and Takeda, 2009) and stored as vitellins in yolk granules Giorgi et al, 1999). The vitellins are the major egg yolk proteins in insects and are important for embryo nourishment Giorgi et al, 1999;Tufail and Takeda, 2008).…”

Section: Introductionmentioning

confidence: 99%

Juvenile hormone downregulates vitellogenin production in Ectatomma tuberculatum (Hymenoptera: Formicidae) sterile workers

Azevedo

Paula

Zanúncio

et al. 2015

Journal of Experimental Biology

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In the ant Ectatomma tuberculatum (Olivier 1792), workers have active ovaries and lay trophic eggs that are eaten by the queen and larvae. Vitellogenins are the main proteins found in the eggs of insects and are the source of nutrients for the embryo in the fertilized eggs and for adults in the trophic eggs. In social insects, vitellogenin titres vary between castes and affect reproductive social status, nursing, foraging, longevity, somatic maintenance, and immunity. In most insects, vitellogenin synthesis is mainly regulated by juvenile hormone. However, in non-reproductive worker ants, this relationship is poorly characterized. This study determined the effects of juvenile hormone on vitellogenin synthesis in non-reproductive E. tuberculatum workers. Juvenile hormone was topically applied onto workers, and the effect on vitellogenin synthesis in the fat body and vitellogenin titres in the haemolymph were analysed by ELISA and qPCR. Juvenile hormone downregulated protein synthesis and reduced vitellogenin titres in the haemolymph, suggesting that in workers of E. tuberculatum, juvenile hormone loses its gonadotrophic function.

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“…These presumably would include Golgi, tubules, exocytotic vesicles, coated vesicles, early and late endosomes, and lysosomes, all of which are likely to have functional roles during such events as production of the embryonic cuticle (cf. Criel, 1991), formation of yolk platelets (Giorgi et al, 1999;Warner et al, 2002) and yolk degradation (Komazaki and Hiruma, 1999;Perona et al, 1988;Vallejo, 1985, 1989). Indeed, membrane-bound yolk platelets themselves should be considered, as they are acidified to varying degrees for both maintenance and degradation in other species (Abreu et al, 2004;Fagotto, 1995;Fausto et al, 2001) and contain very little P i in A. franciscana (Warner and Huang, 1979).…”

mentioning

confidence: 99%

V-ATPase expression during development ofArtemia franciscanaembryos: potential role for proton gradients in anoxia signaling

Covi

Hand

2005

Journal of Experimental Biology

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Underanoxia, Artemia franciscana embryos downregulate metabolic processes and approach an ametabolic state. Entrance into this quiescent state is accompanied by a profound acidification of the intracellular space, and more than two decades of research now clearly demonstrates that this acidification is critical to metabolic downregulation in anoxic embryos. However, the proximal mechanisms responsible for the pH shift remain largely unidentified. Here, we report evidence demonstrating expression of the V-ATPase in encysted embryos and present an argument for its involvement in the intracellular acidification induced by anoxia. We identified a single B-subunit cDNA sharing the greatest degree of sequence similarity with 'generalisttype' homologues from mammals (brain-type) and invertebrates. Quantitative analysis of B-subunit mRNA demonstrates differential expression throughout early development, and western blot analyses confirm the expression of at least six V-ATPase subunits in both heavy membranes and microsomal vesicles. The critical need for proton pumping during the anoxia-tolerant stage of development is demonstrated by incubation with the VATPase inhibitor bafilomycin A 1 , which halts embryonic development. Importantly, net proton flux from VATPase-acidified compartments to the surrounding cytoplasm is likely under anoxia and may significantly contribute to the enigmatic acidification critical to quiescence.

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Differential vitellin polypeptide processing in insect embryos

Cited by 71 publications

References 136 publications

Localization and function ofRhipicephalus (Boophilus) microplusvitellin-degrading cysteine endopeptidase

Localization and function ofRhipicephalus (Boophilus) microplusvitellin-degrading cysteine endopeptidase

Juvenile hormone downregulates vitellogenin production in Ectatomma tuberculatum (Hymenoptera: Formicidae) sterile workers

V-ATPase expression during development ofArtemia franciscanaembryos: potential role for proton gradients in anoxia signaling

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