Nurper Güz

Next Generation Sequencing Based Transcriptome Analysis of Septic-Injury Responsive Genes in the Beetle Tribolium castaneum

Beetles (Coleoptera) are the most diverse animal group on earth and interact with numerous symbiotic or pathogenic microbes in their environments. The red flour beetle Tribolium castaneum is a genetically tractable model beetle species and its whole genome sequence has recently been determined. To advance our understanding of the molecular basis of beetle immunity here we analyzed the whole transcriptome of T. castaneum by high-throughput next generation sequencing technology. Here, we demonstrate that the Illumina/Solexa sequencing approach of cDNA samples from T. castaneum including over 9.7 million reads with 72 base pairs (bp) length (approximately 700 million bp sequence information with about 30× transcriptome coverage) confirms the expression of most predicted genes and enabled subsequent qualitative and quantitative transcriptome analysis. This approach recapitulates our recent quantitative real-time PCR studies of immune-challenged and naïve T. castaneum beetles, validating our approach. Furthermore, this sequencing analysis resulted in the identification of 73 differentially expressed genes upon immune-challenge with statistical significance by comparing expression data to calculated values derived by fitting to generalized linear models. We identified up regulation of diverse immune-related genes (e.g. Toll receptor, serine proteinases, DOPA decarboxylase and thaumatin) and of numerous genes encoding proteins with yet unknown functions. Of note, septic-injury resulted also in the elevated expression of genes encoding heat-shock proteins or cytochrome P450s supporting the view that there is crosstalk between immune and stress responses in T. castaneum. The present study provides a first comprehensive overview of septic-injury responsive genes in T. castaneum beetles. Identified genes advance our understanding of T. castaneum specific gene expression alteration upon immune-challenge in particular and may help to understand beetle immunity in general.

Molecular characterization of Ephestia kuehniella (Lepidoptera: Pyralidae) transferrin and its response to parasitoid Venturia canescens (Hymenoptera: Ichneumonidae Gravenhorst)

In the present study, we characterized a full‐length cDNA encoding a putative iron‐binding protein transferrin from the lepidopteran Mediterranean flour moth (EkTrf, 2397 bp). The putative EkTrf is 683 amino acids with a molecular mass of approximately 76u2003kDa. The deduced amino acid sequence showed significant homology with other insect transferrins from Chilo suppressalis (76%), Galleria mellonella (75%), Plutella xylostella (72%), Manduca sexta (74%), Bombyx mori (73%), Spodoptera litura and (72%), Choristoneura fumiferana (71%). Northern blot analysis indicated that Ephestia transferrin mRNA was expressed in the last larval instars of both males and females and in the pupal developmental stages. EkTrf is expressed predominantly in the fat body and ovary tissues. Analysis of parasitized larva by the endoparasitoid Venturia canescens suggests that transferrin expression is induced following parasitoid challenge. Expression of EkTrf levels also increased upon bacterial infection at 6u2003h post treatment and remained high until 24u2003h. Similarly to other insect transferrins, EkTrf may play a role in immunity through its iron‐binding capacity.

Identification and coordinated expression of perilipin genes in the biological cycle of sunn pest, Eurygaster maura (Hemiptera: Scutelleridae): Implications for lipolysis and lipogenesis

The sunn pest, Eurygaster spp., is one of the most destructive pests of grains in Asia, Europe and Africa. The nymphs and adults feed voraciously in the field by late-spring, followed by migration of adults into mountains for diapause, which includes estivation by late summer and hibernation during winter. Adults migrate back to the field by the end of diapause in mid-spring, where they mate and lay eggs. To understand how sunn pest survives and maintains basic metabolic functions without feeding for 7 months during diapause, this study focused on lipid metabolism as the major source of energy production, and the primary organ of lipid metabolism, the fat body. Studies on lipid metabolism revealed two major factors referred to perilipin protein family, Lipid Storage Droplet Protein 1 (LSD1) and Lipid Storage Droplet Protein 2 (LSD2), which are involved in hydrolysis and accumulation of lipids, respectively. In this study, two LSD (EmLSD1-2) orthologues in the hemimetabolous Eurygaster maura were identified. EmLSD1 and EmLSD2 genes were expressed in multiple tissues, but primarily in fat body. Both genes were continuously expressed throughout the insects life cycle but peaked in the 4th nymphal stage. Their expression patterns were in accordance with the biological roles of LSDs. EmLSD1 expression peaked in non-feeding stages supporting its lipolytic role, while the highest level of EmLSD2 expression was in feeding stages supporting its lipogenetic role. Expression patterns of both genes differed in females and males. Overall, expression patterns of EmLSDs provide clues to understanding the interesting life cycle of sunn pest.

Aphid parasitoids (Hymenoptera: Braconidae: Aphidiinae) on weeds from Ankara, Turkey

Studies were conducted during the years 2001–2003 to determine the parasitoids of Aphidoidea (Homoptera) species on weeds in Ankara province. Six genera and ten species of aphid parasitoids belonging to Braconidae were determined. The tritrophic associations of plant/aphid/parasitoid were analyzed. Forty-four associations of aphidiinae wasps, host aphids and host plants new to the Mediterranean region and 71 new associations for Turkish fauna were reported.

Usage of molecular markers in insect systematics

Insect systematics is based on morphological characters. However, molecular marker systems have been developed in recent years especially in order to discriminate closely related species and in order to identify the species which couldn’t be distinguished by systematic methods currently employed. Molecular markers can be divided into DNA markers and protein markers. DNA markers have been widely used due to the disadvantages of allozymes and isozymes which can be referred as protein markers. In this review preservation of samples for DNA analysis are summarized and widely used molecular techniques are described. The current techniques are compared to each other as well as the advantages and disadvantages of these techniques are discussed. Furthermore target genes used in DNA sequence analysis and their potentials in systematic research have been overviewed.