Sequestration of storage protein 1 (SP1) in differentiated fat body tissues of the female groundnut pest Amsacta albistriga (Lepidoptera: Arctiidae)

Abstract

The transformation from larval caterpillar to non-feeding pupa and adult moth involves a complete remodelling and restructuring of an insect and its organs. In the groundnut pest Amsacta albistriga Walker, the female sex-specific storage protein 1 (SP1) was monitored from last larval instars, during pupal development to the adult stage. Staining intensity of SP1 (which resolved at 82 kDa) in the peripheral fat body (PF) tissues subjected to 10% SDS-PAGE was maximum at mid-stage last larval instars and declined subsequently. However, in perivisceral fat body (PVF) tissues, the staining intensity of SP1 increased significantly from mid-stage final instar. The presence of SP1 during pupal ovary and adult ovariole development and its availability during egg development was confirmed by immunoblot analysis. Electron microscopy data revealed that the decline of biosynthesis of SP1 in PF tissues and its disintegration were associated with the appearance of irregular nucleus and autophagic vacuoles during transformation of larva to pupa. In vitro and in vivo studies using [ 35 S]-methionine-labelled storage proteins showed that, unlike PF tissues, PVF tissue sequestered a significant amount of labelled SP1. During this transformation, SP1 was mainly sequestered as storage protein granules until they served as sources of amino acids for the production of egg yolk proteins. Localization of clathrin-coated pits and crystalline storage proteins was confirmed by immunogold tracer techniques.

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

“…This HcSP1 antibody strongly cross-reacts with storage protein 1 from red hairy caterpillar (Chandrasekar, 2006;Chandrasekar et al, 2007).…”

“…length) in an environmental chamber and were maintained on leaves of Arachis hypogea at laboratory temperature (26.19°C ± 0.38°C), humidity (>60%), and a photo-period of 12L:12D (Chandrasekar, 2006).…”

“…SP1 is designated as female SP; however, SP2 can be seen in both sexes (Telfer and Kunkel, 1991;Silhacek et al, 1994;Vanishree, et al, 2005;Chandrasekar, 2006;Chandrasekar et al, 2007). In all insects, some hexamers are rich in aromatic amino acids, especially phenylalanine and tyrosine (up to 25% Phe+Tyr) (Wyatt and Pan, 1978), called arylphorin (SP2) (Telfer et al, 1983).…”

“…It has been utilized for the non-feeding pupal stage; mainly for cuticle development (Scheller et al, 1980;Kaliafas et al, 1984;Konig et al, 1986;Peter and Scheller 1991). In contrast to all other classes of SPs, methoinine-rich proteins (SP1, 82 kDa) are more abundant in female than in male larvae (Ryan et al, 1985;Tojo et al, 1980;Chandrasekar, 2006). Generally, Met-rich SP exhibits sexual dimorphism; in some species, only traces of it occur in males (Telfer and Kunkel, 1991).…”

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

“…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 ].…”