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JLT



Posts: 740
Joined: Jan. 2008

(Permalink) Posted: Feb. 17 2009,09:06   

Polydnaviruses of Braconid Wasps Derive from an Ancestral Nudivirus
Science 13 February 2009: Vol. 323. no. 5916, pp. 926 - 930. DOI: 10.1126/science.1166788 Link

For some background: Not merely bioweaponized, but mutualistic bioweaponized wasps (Mystery rays from outer space)

The abstract:
 
Quote
Many species of parasitoid wasps inject polydnavirus particles in order to manipulate host defenses and development. Because the DNA packaged in these particles encodes almost no viral structural proteins, their relation to viruses has been debated. Characterization of complementary DNAs derived from braconid wasp ovaries identified genes encoding subunits of a viral RNA polymerase and structural components of polydnavirus particles related most closely to those of nudiviruses—a sister group of baculoviruses. The conservation of this viral machinery in different braconid wasp lineages sharing polydnaviruses suggests that parasitoid wasps incorporated a nudivirus-related genome into their own genetic material. We found that the nudiviral genes themselves are no longer packaged but are actively transcribed and produce particles used to deliver genes essential for successful parasitism in lepidopteran hosts.

And a bit from the article itself:
 
Quote
Comparative genomic studies have highlighted the role of symbiotic associations in evolution (1). Polydnaviruses (PDVs) are virus-like particles associated with wasp species that parasitize lepidopteran larvae. PDV particles are injected along with the eggs of the wasp into the lepidopteran larvae (or eggs) and express proteins that interfere with host immune defenses, development, and physiology; this interference enables wasp larvae to survive and develop within the host (2). Viral particle production occurs exclusively in a specialized region of the wasp ovaries (the calyx), and the vertically transmitted virus does not initiate particle production in the infected host tissues (3). The viral genome packaged in the particles is composed of multiple double-stranded DNA (dsDNA) circles, and it is surprising that it encodes almost no viral structural proteins, although it harbors immunosuppressive genes that are expressed in the host and are essential for successful parasitism (4, 5) (see PDV description at www.ictvonline.org). Because of this lack of genes coding for structural proteins, it has been debated whether PDVs are of viral origin or a "genetic secretion" of the wasp (6, 7).
PDVs are classified as either bracoviruses or ichnoviruses, when associated with braconid or ichneumonid wasps, respectively. Detailed phylogenetic studies have shown that the bracovirus-associated wasps form a monophyletic group known as the microgastroid complex (8), and it has been hypothesized that there has been a single integration event of a viral genome, as a provirus, in the microgastroid lineage. This predicts that vertically transmitted viral DNA may have been maintained because of its contribution to successful parasitism and that PDVs have contributed to the diversification of the microgastroid complex of at least 17,500 species (8).


And finally accompanying commentary.

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"Random mutations, if they are truly random, will affect, and potentially damage, any aspect of the organism, [...]
Thus, a realistic [computer] simulation [of evolution] would allow the program, OS, and hardware to be affected in a random fashion." GilDodgen, Frilly shirt owner

  
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