Expression and localization of storage protein 1 (SP1) in differentiated fat body tissues of red hairy caterpillar,Amsacta albistrigaWalker

Abstract

The accumulation and utilization of storage proteins are prominent events linked to the metamorphosis of holometabolous insects. The female-specific storage protein 1 (SP1) is the major storage protein found in the hemolymph and fat body of female larvae of the groundnut pest, Amsacta albistriga. Here we show SP1 expression and localization in differentiated fat body tissues using biochemical and immunohistochemistry scrutiny. Comparison of A. albistriga SP1 with that of other species with respect to amino acid composition and N-terminal sequences show that SP1 is a methonine-rich protein and its identity was confirmed by means of immunoblot analysis. Northern blot studies revealed that the SP1 gene demonstrates stage- and tissue-specific expression in the peripheral fat body cells during the mid-larval period of fifth instar of A. albistriga. During the larval pupal transformation, SP1 are sequestered mainly by the perivisceral fat body tissues, until they serve the purpose of supplying amino acids for the production of egg yolk proteins. Further, electron microscopic studies using immunogold tracer techniques confirmed the localization of crystalline SP1 reserves, stored in the perivisceral fat body tissues. Hence, the peripheral fat body is responsible for biosynthesis of storage proteins, whereas the perivisceral fat body is a specialized storage organ.

Two storage hexamerins from the beet armyworm Spodoptera exigua: Cloning, characterization and the effect of gene silencing on survival

“…AalSP1 expression gradually increased from day-1 to day-7 final instar larvae [30]. It has been reported that expression levels of insect storage proteins (including Hex1, Hex2, SP1 and SP2) reach a maximum in the last stage of final instar larvae [31,54]. SeHex and SeSP1 mRNA expression also reached a maximum in the final stage (pre-pupae) of last instar larvae (Figure 3B).…”

“…We found that SeHex was expressed not only in fat body and midgut, but also in cuticle and Malpighian tubules (Figure 3A). SP1 in Amsacta albistriga was detected in fat body and pupal ovary [31]. However, the results for SeSP1 reveal that it is expressed in fat body, Malpighian tubules and tracheae (Figure 3A).…”

“…So far, SPs and hexamerins have been cloned and studied in Musca domestica [21], Apriona germari [22,23], Apis mellifera [5], Drosophila melanogaster [24] and Reticulitermes flavipes [25]. In Lepidoptera, SPs and hexamerins have been cloned and studied in Spodoptera litura [26], Plodia interpunctella [2], Corcyra cephalonica [27], Manduca sexta [28], Amsacta albistriga [29-31], Plutella xylostella [32], Helicoverpa zea [33], Omphisa fuscidentalis [34], and Sesamia nonagrioides [35,36]. …”

Expression profile of cuticular genes of silkworm, Bombyx mori

“…In contrast to numerous up-regulated genes, only two down-regulated genes were detected. SP1 is considered as a storage protein in hemolymph and ovary associated with the development of Lepidoptera insects [34,35]. Another down-regulated gene, chitinase-related protein 1 showed high identity to chitinase.…”

Parasitoid venom induces metabolic cascades in fly hosts

“…It is known that insects sequester FAAs into storage proteins in fat bodies and re-release them during metamorphosis to synthesize other proteins (Chandrasekar et al, 2008; Hunt et al, 2003; Wang and Haunerland, 1993; Wheeler et al, 2000), which likely explain this pattern. Tyrosine and tryptophan metabolism increase in Control hosts and are known to play key roles in cuticular sclerotization (Andersen, 2010) and development of the eye (Linzen and Schartau, 1974; Han et al, 2007).…”