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The evolutionary importance of hybridization and introgression has long been debated. Hybrids are usually rare and unfit, but even infrequent hybridization can aid adaptation by transferring beneficial traits between species. Here we use genomic tools to investigate introgression in Heliconius, a rapidly radiating genus of neotropical butterflies widely(More)
BACKGROUND Post-transcriptional regulation in eukaryotes can be operated through microRNA (miRNAs) mediated gene silencing. MiRNAs are small (18-25 nucleotides) non-coding RNAs that play crucial role in regulation of gene expression in eukaryotes. In insects, miRNAs have been shown to be involved in multiple mechanisms such as embryonic development, tissue(More)
This paper presents evidence that Thosea asigna virus (TaV) has a unique capsid expression strategy and is a member of the Nudaurelia beta-like genus of the Tetraviridae. Electron microscopy of TaV particles indicated a 38 nm, T = 4 icosahedral capsid similar in structure to that of Nudaurelia beta virus (NbetaV). TaV particles have a buoyant density of(More)
The pathways that allow short noncoding RNAs such as the microRNAs (miRNAs) to mediate gene regulation and control critical cellular and developmental processes involve a limited number of key protein components. These proteins are the Dicer-like RNases, double-stranded RNA (dsRNA)-binding proteins, and the Argonaute (AGO) proteins that process stem-loop(More)
The use of conventional chemical insecticides and bacterial toxins to control lepidopteran pests of global agriculture has imposed significant selection pressure leading to the rapid evolution of insecticide resistance. Transgenic crops (e.g., cotton) expressing the Bt Cry toxins are now used world wide to control these pests, including the highly(More)
We have chemically characterized a preparation of halitoxins, (1,3 alkyl-pyridinium salts) isolated from the marine sponge Callyspongia ridleyi. At concentrations of 50 and 5 microg/ml the halitoxin preparation caused irreversible membrane potential depolarization, decreased input resistance and inhibited evoked action potentials when applied to cultured(More)
Piwi-interacting RNAs (piRNAs) are known to regulate transposon activity in germ cells of several animal models that propagate sexually. However, the role of piRNAs during asexual reproduction remains almost unknown. Aphids that can alternate sexual and asexual reproduction cycles in response to seasonal changes of photoperiod provide a unique opportunity(More)
The Tetraviridae are a family of small, non-enveloped, insect RNA viruses consisting of one or two single-stranded, positive-sense genomic RNAs encapsidated in an icosahedral capsid with T=4 symmetry. Tetravirus procapsids undergo maturation when exposed to a low pH environment in vitro. While the structural biology of the conformational changes that(More)
A small RNA virus with novel characteristics has been isolated from laboratory-bred larvae of Helicoverpa armigera. Infection by the H. armigera stunt virus causes severe retardation of larval development and subsequent death. Its particles are isometric, 38 nm in diameter, and have a buoyant density of 1.296 g/ml in caesium chloride. The viral capsid has(More)
Drosophila possesses the core gene silencing machinery but, like all insects, lacks the canonical RNA-dependent RNA polymerases (RdRps) that in C. elegans either trigger or enhance two major small RNA-dependent gene silencing pathways. Introduction of two different nematode RdRps into Drosophila showed them to be functional, resulting in differing silencing(More)