Microarray-based transcriptomic analysis of differences between long-term gregarious and solitarious desert locusts

Abstract

Desert locusts (Schistocerca gregaria) show an extreme form of phenotypic plasticity and can transform between a cryptic solitarious phase and a swarming gregarious phase. The two phases differ extensively in behavior, morphology and physiology but very little is known about the molecular basis of these differences. We used our recently generated Expressed Sequence Tag (EST) database derived from S. gregaria central nervous system (CNS) to design oligonucleotide microarrays and compare the expression of thousands of genes in the CNS of long-term gregarious and solitarious adult desert locusts. This identified 214 differentially expressed genes, of which 40% have been annotated to date. These include genes encoding proteins that are associated with CNS development and modeling, sensory perception, stress response and resistance, and fundamental cellular processes. Our microarray analysis has identified genes whose altered expression may enable locusts of either phase to deal with the different challenges they face. Genes for heat shock proteins and proteins which confer protection from infection were upregulated in gregarious locusts, which may allow them to respond to acute physiological challenges. By contrast the longer-lived solitarious locusts appear to be more strongly protected from the slowly accumulating effects of ageing by an upregulation of genes related to anti-oxidant systems, detoxification and anabolic renewal. Gregarious locusts also had a greater abundance of transcripts for proteins involved in sensory processing and in nervous system development and plasticity. Gregarious locusts live in a more complex sensory environment than solitarious locusts and may require a greater turnover of proteins involved in sensory transduction, and possibly greater neuronal plasticity.

Figure 1. Adult gregarious and solitarious desert locusts.

The upper and lower panels show males (♂) and females (♀) of the gregarious (G) or solitarious (S) phases.

Figure 2. Classification of the annotated differentially expressed genes under GO categories.

The number of transcripts classified under different GO terms that were more abundant in gregarious (red) and solitarious (green) locusts.

Figure 3. Pairwise alignment of the sequences corresponding to LC.4273.C1.Contig4391 and LC.4273.C2.Contig4392.

The alignment was performed in ClustalW2 software ; (input sequences were defined as DNA, other parameters were set at default values). Conserved residues are highlighted in black. Purine transition mutations are shaded.