Identification and characterization of circadian clock genes in the pea aphid Acyrthosiphon pisum

The molecular basis of circadian clocks is highly evolutionarily conserved and has been best characterized in Drosophila and mouse. Analysis of the Acyrthosiphon pisum genome revealed the presence of orthologs of the following genes constituting the core of the circadian clock in Drosophila: period (per), timeless (tim), Clock, cycle, vrille, and Pdp1. However, the presence in A. pisum of orthologs of a mammal-type in addition to a Drosophila-type cryptochrome places the putative aphid clockwork closer to the ancestral insect system than to the Drosophila one. Most notably, five of these putative aphid core clock genes are highly divergent and exhibit accelerated rates of change (especially…

Sex versus parthenogenesis: A transcriptomic approach of photoperiod response in the model aphid Acyrthosiphon pisum (Hemiptera: Aphididae)

International audience; Most aphids develop a cyclic parthenogenesis life-cycle. After several generations of viviparous parthenogenetic females, it follows a single annual generation of sexual individuals, usually in autumn, that mate and lay the sexual eggs. Shortening of photoperiod at the end of the summer is a key factor inducing the sexual response. With the survey here reported we aimed at identifying a collection of candidate genes to participate at some point in the cascade of events that lead to the sexual phenotypes. Following a suppression subtractive hybridization methodology (SSH) on the model aphid Acyrthosiphon pisum, we built and characterised two reciprocal cDNA libraries …

Identification, characterization and analysis of expression of genes encoding arylalkylamine N-acetyltransferases in the pea aphidAcyrthosiphon pisum

Most organisms exhibit some kind of rhythmicity in their behaviour and/or physiology as an adaptation to the cyclical movements of the Earth. In addition to circadian rhythms, many organisms have an annual rhythmicity in certain activities, such as reproduction, migration or induction of diapause. Current knowledge of the molecular basis controlling seasonal rhythmicity, especially in insects, is scarce. One element that seems to play an essential role in the maintenance of both circadian and seasonal rhythms in vertebrates is the hormone melatonin. In vertebrates, the limiting enzyme in its synthesis is the arylalkylamine N-acetyltransferase (AANAT). Melatonin is also present in insects bu…

Aphids are the leading pests in agricultural crops. A large-scale sequencing of 40,904 ESTs from the pea aphid Acyrthosiphon pisum was carried out to define a catalog of 12,082 unique transcripts. A strong AT bias was found, indicating a compositional shift between Drosophila melanogaster and A. pisum. An in silico profiling analysis characterized 135 transcripts specific to pea-aphid tissues (relating to bacteriocytes and parthenogenetic embryos). This project is the first to address the genetics of the Hemiptera and of a hemimetabolous insect.