EST-based profiling and comparison of gene expression in the silkworm fat body during metamorphosis

Abstract

The fat body plays key roles in metabolism and sustenance of growth throughout the life of a silkworm, and thus represents a model tissue for studying development and metamorphosis. Analysis of 18,480 ESTs derived from larval and pupal fat body cDNA libraries allowed characterization of gene expression patterns in the fat body during metamorphosis. By Phrap assembling, 6,814 estimated transcription units (TUs) were generated, 2,673 of which contained 60% of the total ESTs and represented 1,366 distinctive known genes. These genes were classified into 14 categories based on their known or putative functions, and most were found to be involved in metabolism and cell defense. Further comparative analysis of the expression profiles revealed that the gene expression patterns in the larval fat body strikingly differed from those in the pupal fat body. From this, we identified a subset of genes potentially associated with metamorphic events such as the formation or destruction of specific tissues, and simultaneously confirmed the stage-specific expression patterns of several identified genes using RT-PCR examination. This work will provide a valuable resource for studying regulatory mechanisms associated with fat body developmental changes and silkworm metamorphosis. Abbreviations used: cDNA = DNA complementary to RNA; bp = base pair; PCD = programmed cell death; EST = expressed sequence tag; GOC = gene ontology consortium; RT-PCR = reverse transcription polymerase chain reaction; TU = transcription unit; EB = ethidium bromide; LSP = larva storage protein; AKH = adipokinetic hormone; BBP = bilin binding protein; WGS = whole genome sequence.

Insect Fat Body: Energy, Metabolism, and Regulation

“…Clearly, the fat body is a multifunctional organ, as reflected by the transcriptome pattern observed from D. melanogaster and Bombyx mori (32, 70). …”

Differentially expressed genes in the fat body of Bombyx mori in response to phoxim insecticide

“…At the same time, the fat body is the target tissue of several hormones, produces several antimicrobial peptides, and participates in detoxification of nitrogen metabolism [1][2][3]. Clearly, the fat body is a multifunctional tissue, as reflected by the transcriptome pattern observed from Drosophila melanogaster and B. mori [4,5].…”

Energetics of pupal-adult metamorphosis in the silkworm, Bombyx mori : An analysis of transdeamination parameters in the fat body and haemolymph

“…Further, it synthesizes a variety of haemolymph proteins, metabolites and antimicrobial peptides apart from detoxifying harmful products of nitrogen metabolism (Keeley, 1985).Biochemical studies on fruit fly and mosquitoes have shown that the fat body specifically expresses amino acid transporters that function as nutrient sensors (Attardo et al, 2005). The silkworm fat body displays morphological distinctions and works as a region-specific multifunctional organ and mobilizes cellular proteins, amino acids, carbohydrates and lipids as energy reservoirs by integrating signals from neighbouring tissues (Haunerl and Shirk, 1995;Gade, 2004;Seong et.al, 2005;Yaginuma and Ushizima, 2005;Cheng et al, 2006). In this energy-intensive process, some reserve proteins are degraded to individual amino acids, each one of which has its own metabolic destination that generates energy This work is licensed under Attribution-Non Commercial 4.0 International (CC BY-NC 4.0).…”