Lysine Acetyltransferase p300/CBP Plays an Important Role in Reproduction, Embryogenesis and Longevity of the Pea Aphid Acyrthosiphon pisum

CREB-binding protein (p300/CBP) is a universal transcriptional co-regulator with lysine acetyltransferase activity. Drosophila melanogaster p300/CBP is a well-known regulator of embryogenesis, and recent studies in beetles and cockroaches have revealed the importance of this protein during post-embryonic development and endocrine signaling. In pest insects, p300/CBP may therefore offer a useful target for control methods based on RNA interference (RNAi). We investigated the role of p300/CBP in the pea aphid (Acyrthosiphon pisum), a notorious pest insect used as a laboratory model for the analysis of complex life-history traits. The RNAi-based attenuation of A. pisum p300/CBP significantly reduced the aphid lifespan and number of offspring, as well as shortening the reproductive phase, suggesting the manipulation of this gene contributes to accelerated senescence. Furthermore, injection of p300/CBP dsRNA also reduced the number of viable offspring and increased the number of premature nymphs, which developed in abnormally structured ovaries. Our data confirm the evolutionarily conserved function of p300/CBP during insect embryogenesis and show that the protein has a critical effect on longevity, reproduction and development in A. pisum. The potent effect of p300/CBP silencing indicates that this regulatory protein is an ideal target for RNAi-based aphid control.

Insect embryogenesis – what is ancestral and what is derived?

The systematic genetic analysis of Drosophila development has provided us with a deep insight into the molecular pathways of early embryogenesis. The question arises now whether these insights can serve as a more general paradigm of early development, or whether they apply only to advanced insect orders. Though it is too early to give a definitive answer to this question, we suggest that there is currently no firm reason to believe that the molecular mechanisms that were elucidated in Drosophila may not also apply to other forms of insect embryogenesis. Thus, many of the Drosophila genes involved in early pattern formation may have comparable functions in other insects and possibly throughout the arthropods.

Pair-rule expression of a cell surface molecule during gastrulation of the moth embryo

The TN1 monoclonal antibody recognizes a cell surface epitope that is present on subsets of growing axons in the developing nervous system of moth embryos. This antigen is also found in a variety of other developing tissues: in all cases its expression is cell-specific and transient. Here we show that the first expression of the TN1 epitope in moth embryos occurs specifically on the surfaces of mesodermal cells during gastrulation, and that it is limited to alternate segments. Creation of this pair-rule pattern of expression includes indications of an initial 4-segment periodicity, and transient immunoreactivity in ‘off’ segments. The alternating pattern is most dramatic at the end of gastrulation. It changes rapidly such that, during organogenesis, the TN1 antigen(s) is expressed in many developing tissues of all segments, with little segment-specific variation. Immunolabelling of living embryos under culture conditions demonstrated that the TN1 epitope(s) is associated with cell surfaces, both during neurogenesis and during the earlier period of gastrulation. These observations indicate that pair-rule gene functions operate in insects other than Diptera and suggest that cell surface molecules may be utilized early in insect embryogenesis in the initial establishment of large body regions.