scholarly journals Effect of Tetra-nortriterpenoid on the Fourth and Fifth Larval Instar of Spodoptera littoralis

2020 ◽  
Vol 03 (01) ◽  
Author(s):  
Ebrahim Eissa ◽  
Salama Ahmed Salama ◽  
Khaled Hashem Radwan ◽  
Eman Hashem Radwan
Keyword(s):  
Spodoptera Littoralis ◽  
Larval Instar

scholarly journals Characterization of a sterol carrier protein 2/3-oxoacyl-CoA thiolase from the cotton leafworm (Spodoptera littoralis): a lepidopteran mechanism closer to that in mammals than that in dipterans

2004 ◽  
Vol 382 (1) ◽  
pp. 93-100 ◽  
Author(s):  
Hajime TAKEUCHI ◽  
Jian-Hua CHEN ◽  
John R. JENKINS ◽  
Masanori BUN-YA ◽  
Philip C. TURNER ◽  
...  
Keyword(s):  
Spodoptera Littoralis ◽  
De Novo ◽  
Larval Instar ◽  
Constitutive Expression ◽  
Northern Blotting ◽  
Malpighian Tubules ◽  
Carrier Protein ◽  
Sterol Carrier Protein ◽  
Cotton Leafworm ◽  
Sterol Carrier Protein 2

Numerous invertebrate species belonging to several phyla cannot synthesize sterols de novo and rely on a dietary source of the compound. SCPx (sterol carrier protein 2/3-oxoacyl-CoA thiolase) is a protein involved in the trafficking of sterols and oxidation of branched-chain fatty acids. We have isolated SCPx protein from Spodoptera littoralis (cotton leafworm) and have subjected it to limited amino acid sequencing. A reverse-transcriptase PCR-based approach has been used to clone the cDNA (1.9 kb), which encodes a 57 kDa protein. Northern blotting detected two mRNA transcripts, one of 1.9 kb, encoding SCPx, and one of 0.95 kb, presumably encoding SCP2 (sterol carrier protein 2). The former mRNA was highly expressed in midgut and Malpighian tubules during the last larval instar. Furthermore, constitutive expression of the gene was detected in the prothoracic glands, which are the main tissue producing the insect moulting hormone. There was no significant change in the 1.9 kb mRNA in midgut throughout development, but slightly higher expression in the early stages. Conceptual translation of the cDNA and a database search revealed that the gene includes the SCP2 sequence and a putative peroxisomal targeting signal in the C-terminal region. Also a cysteine residue at the putative active site for the 3-oxoacyl-CoA thiolase is conserved. Southern blotting showed that SCPx is likely to be encoded by a single-copy gene. The mRNA expression pattern and the gene structure suggest that SCPx from S. littoralis (a lepidopteran) is evolutionarily closer to that of mammals than to that of dipterans.

scholarly journals Enzymes of ecdysteroid transformation and inactivation in the midgut of the cotton leafworm, Spodoptera littoralis: properties and developmental profiles

1995 ◽  
Vol 312 (2) ◽  
pp. 561-568 ◽  
Author(s):  
T J Webb ◽  
R Powls ◽  
H H Rees
Keyword(s):  
Spodoptera Littoralis ◽  
Larval Instar ◽  
Physiological Significance ◽  
Peak Activity ◽  
Cotton Leafworm ◽  
Clear Preference ◽  
Prothoracic Glands ◽  
Developmental Profiles

In the midgut cytosol of Lepidoptera, ecdysteroids undergo inactivation by transformation via the 3-dehydro derivative to the corresponding 3-epiecdysteroid (3 alpha-hydroxy) and by phosphate conjugation. The oxygen-dependent oxidase catalyses formation of 3-dehydroecdysteroid, which can be reduced either irreversibly by 3-dehydroecdysone 3 alpha-reductase to 3-epiecdysteroid, or by 3-dehydroecdysone 3 beta-reductase back to the initial ecdysteroid. Furthermore, these ecdysteroids undergo further inactivation by phosphorylation. These ecdysteroid transformations have been investigated in last instar larvae of the cotton leafworm, Spodoptera littoralis. The products of the phosphorylation have been characterized as predominantly ecdysteroid 2-phosphate accompanied by smaller amounts of the corresponding 22-phosphate. The phosphotransferases require Mg2+ and ATP. Whereas the 3-dehydroecdysone 3 alpha-reductase has a clear preference for NADPH rather than NADH, the corresponding 3 beta-reductase markedly favours NADH. The physiological significance of the latter enzyme is unclear. The profiles of the various enzymic activities in dialysed midgut cytosol supplemented with appropriate cofactors were determined throughout the last larval instar. All activities were detectable throughout the instar, but the respective enzymes exhibited maxima at different times. Ecdysone oxidase showed a peak early in the instar, with 3-dehydroecdysone 3 alpha-reductase increasing to a peak as the former activity declined. The 3-dehydroecdysone 3 beta-reductase exhibited peak activity late in the instar, a profile similar to that observed for the corresponding haemolymph enzyme involved in reduction of the 3-dehydroecdysone product of the prothoracic glands to ecdysone. Thus, the significance of the midgut 3 beta-reductase may be related to production of active hormone. Both ecydsteroid 22- and 2-phosphotransferases showed high activities early in the instar and then declined. The physiological significance of the profiles for the ecdysone oxidase, the 3-dehydroecdysone 3 alpha-reductase and phosphotransferases is unclear.

scholarly journals Characterization of two genes of the polydnavirus of Chelonus inanitus and their stage-specific expression in the host Spodoptera littoralis

2002 ◽  
Vol 83 (5) ◽  
pp. 1075-1085 ◽  
Author(s):  
Andrea Johner ◽  
Beatrice Lanzrein
Keyword(s):  
Amino Acids ◽  
Spodoptera Littoralis ◽  
Larval Instar ◽  
Cell Formation ◽  
Prepupal Stage ◽  
Specific Expression ◽  
Female Wasp ◽  
Larval Parasitoid ◽  
Parasitoid Development

Chelonus inanitus (Braconidae, Hymenoptera) is a solitary egg-larval parasitoid of Spodoptera littoralis. Along with the egg the female wasp injects polydnaviruses, which are prerequisites for successful parasitoid development. The polydnavirus genome is segmented and consists of double-stranded circular DNA. Proviral DNA is integrated in the wasp’s genome; virus replication is restricted to the wasp’s ovary and does not occur in the parasitized host. The polydnavirus of C. inanitus (CiV) protects the parasitoid larva from encapsulation by the host’s immune system and causes a developmental arrest of the host in the prepupal stage. Here we report on the first two cloned CiV genes, which are named CiV14g1 and CiV14g2 because of their localization on segment CiV14. The cDNA of CiV14g1 has a size of 2036 bp; the gene contains seven exons interrupted by six introns of similar size and encodes a putative polypeptide of 548 amino acids. The cDNA of CiV14g2 has a size of 618 bp; the gene consists of three exons and encodes a putative peptide of 77 amino acids. Transcript quantities of both genes are very low up to the penultimate larval instar of the host. In the last instar, at the stage of pupal cell formation, CiV14g1 expression increases about 5-fold and CiV14g2 expression about a 1000-fold. These are the first data to show strong upregulation of polydnavirus genes towards the end of parasitization. These two genes might be involved in the reduction of host ecdysteroids observed at this stage.

scholarly journals Immunological analysis of developmental changes in ecdysone 20-mono-oxygenase expression in the cotton leafworm, Spodoptera littoralis

1994 ◽  
Vol 299 (3) ◽  
pp. 711-717 ◽  
Author(s):  
J H Chen ◽  
T Hara ◽  
M J Fisher ◽  
H H Rees
Keyword(s):  
Spodoptera Littoralis ◽  
Fat Body ◽  
Specific Activity ◽  
Larval Instar ◽  
Close Correlation ◽  
Developmental Changes ◽  
Cotton Leafworm ◽  
Oxygenase Activity ◽  
Adrenodoxin Reductase ◽  
Cytochrome P 450

The developmental changes in ecdysone 20-mono-oxygenase during the sixth larval instar of the cotton leafworm, Spodoptera littoralis, were investigated. The specific activity of mitochondrial ecdysone 20-mono-oxygenase in the fat-body exhibited a distinct peak at 72 h, at which time the larvae stop feeding. Immunoblot analyses, using antibodies raised against components of vertebrate mitochondrial steroidogenic enzyme systems [anti-(cytochrome P-450scc), anti-(cytochrome P-450(11) beta), anti-adrenodoxin and anti-(adrenodoxin reductase) antibodies], revealed the presence of specific immunoreactive polypeptides in fat-body mitochondrial extracts. In addition, these antibodies effectively inhibited fat-body mitochondrial ecdysone 20-mono-oxygenase activity. This suggests that the S. littoralis steroid-hydroxylating system(s) may contain polypeptide components analogous to those present in vertebrates. A close correlation between developmental changes in mitochondrial ecdysone 20-mono-oxygenase activity and the abundance of polypeptides (approx. 66 kDa and 50 kDa) recognized by the anti-(cytochrome P-450(11) beta) antibody and a polypeptide (approx. 52 kDa) recognized by the anti-(adrenodoxin reductase) antibody were observed in both fat-body and midgut. These results suggest that developmental changes in the abundance of components of the ecdysone 20-mono-oxygenase system may play an important role in the developmental regulation of the enzyme expression and, hence, of 20-hydroxyecdysone titre.

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