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At least 163 records · Page 9Linked to original sources
PubMed1973

Insect juvenile hormones: highly potent synthetic mimics.

The substitution of a 7-alkoxy group for the 6,7-epoxy moiety in aryl terpenoid ethers having high juvenile hormone activity has produced several compounds exceptionally active against Tenebrio molitor. The most potent compound [7-ethoxy-1-(p-ethylphenoxy)-3,7-dimethyl-2-octene, called JH-25] is active at the level of 10 picograms per insect, or about 100 times more active than other promising juvenile hormone mimics so far reported. Compound JH-25 was also active against Tribolium confusum.

Biological Assay↗
PubMed2006

Production of recombinant orange-spotted grouper (Epinephelus coioides) luteinizing hormone in insect cells by the baculovirus expression system and its biological effect.

The cDNA sequence encoding orange-spotted grouper lhb (LHbeta) and cga (GTHalpha) subunits were cocloned into baculovirus transfer vectors and expressed in insect Sf9 cells. The results showed that two bands of 15.6 kDa and 11.4 kDa could be detected by SDS-PAGE and a band of 30 kDa could be detected by native PAGE. The recombinant grouper Lh (rgLh) could stimulate the secretion of testosterone (T) and estradiol-17beta (E2) from the gonad in a static incubation system in a time-dependent, but not a dose-dependent, manner. Using in vivo bioassay, the mRNA levels of two aromatases (cyp19a1a [P450aromA] and cyp19a1b [P450aromB]), gnrh (GnRH), lhb, and cga in the pituitary, gonad, and hypothalamus were determined in different groups of orange-spotted groupers treated respectively with rgLh, human chorionic gonadotropin (hCG), and a culture medium of insect cells transformed with an expression vector without lhb and cga subunits. The mRNA levels of cyp19a1a and cyp19a1b rose dramatically after injecting rgLh intraperitoneally, which was consistent with the secretion of sex steroid hormones. Interestingly, the mRNA levels of gnrh dropped in the pituitary, hypothalamus, and gonad, and the mRNA levels of lhb and cga in the pituitary of the experimental group expressed at a higher level than that of the hCG group. These results are in accord with the long positive feedback loop of Lh on gonad sex steroid hormones and the short negative feedback loop of Lh on gnrh mRNA levels. These results indicate that the rgLh is successfully expressed by the baculovirus-insect expression system and that the rgLh has biological activity.

Animals↗
PubMed2007

Insect gonadotropic peptide hormones: some recent developments.

Gonadotropic peptides are a new generation of peptide hormone regulators of insect reproduction. They have been isolated from ovaries, oviducts, or brains of insects. The subject of this paper is insect peptides that exert stimulatory or inhibitory effects on ovarian development and oocyte maturation. On the basis of the literature data and the results of our investigations, the structure and biological properties of different groups of peptides are presented.

Amino Acid Sequence↗
PubMed1992

Past and present studies with ponasterones, the first insect molting hormones from plants.

The search for antitumor compounds from Southeast Asian plants led to ponasterones, the first phytoecdysteroids, just a year after structure determination of ecdysone and 20-hydroxyecdysone. An independent study of Chinese herb constituents by Takemoto et al. at Tohoku University led to the simultaneous and totally independent discovery of phytoecdysteroids. These findings greatly facilitated research in insect and crustacean physiology. The original structural studies on various phytoecdysteroids have led to interdisciplinary bioorganic studies in the area related to ecdysone receptor, ecdysone biosynthetic precursor (or its storage form), crustacean molt inhibitory factors, and so on.

Animals↗
PubMed1977

Enzymatic and chemical synthesis of 3-dehydroecdysterone, a metabolite of the moulting hormone of insects.

3-Dehydroecdysterone, a less polar metabolite of ecdysterone, was synthesized in vitro using either an enzyme (edcysone oxidase, EC 1.1.3.16) or the chemical catalyst platinum. 3-Dehydroecdysterone was purified and characterized by its chromatographic behaviour, its staining properties and by UV, IR, NMR and mass spectroscopy. The compound is 1/15 as active as ecdysone in the Calliphora moulting hormone bioassay. Its biological relevance is discussed.

Alcohol Oxidoreductases↗
PubMed1975

Translation of mRNA for 3,4-dihydroxyphenylalanine decarboxylase isolated from epidermis tissue of Calliphora vicina R. -D. in a heterologous system. Dependence of mRNA concentration on the insect steroid hormone ecdysone.

RNA was isolated from the epidermis of Calliphora vicina larvae by phenol--chloroform extraction. The RN A sedimenting in sucrose gradients between 5 and 18 S was submitted to chromatography on oligo(dT)-cellulose columns. The fraction binding to the oligo(dT) is able to stimulate protein synthesis in a system consisting of mouse liverribosomal subunits, pH-5 factors from rat liver and initiation factors from rabbit reticulocytes. Optimal Mg2+ concentration for the translation of insect mRNA is 3.5 mM, that of K+ 76 MM. Initiation factors prepared from epidermis of Calliphora larvae are less efficient in the translation of insect mRNA than initiation factors isolated from reticulocytes. The pH-5 fraction from epidermis inhibits protein synthesis independent of the source of the mRNA fraction used. One of the proteins synthesized in the reconstituted system under the direction of insect mRNA has been identified as 3,4-dihydroxyphenylalanine (DOPA) decarboxylase by immunoprecipitation with specific antiserum against DOPA decarboxylase and comigration in dodecylsulphate-acrylamide electrophoresis with pure DOPA decarboxylase. Both mRNA from white prepupae and from 6--7-days-old larvae contain sequences coding for DOPA decarboxylase. However, white prepupae contains 3--4 times more DOPA decarboxylase-mRNA than 6--7-days-old larvae. The content of DOPA decarboxylase mRNA is proportional to the amount of active DOPA decarboxylase molecules present in the animals from which the mRNA was isolated.

Animals↗
PubMed1988

Dietary components modulate yolk protein gene transcription in Drosophila melanogaster.

The three yolk proteins of Drosophila melanogaster begin to be synthesized at eclosion. Transcription of the genes is regulated by the genes tra, tra-2 and dsx and also by the insect hormones, juvenile hormone and 20-hydroxyecdysone. We show that there is yet another level of control which is dependent upon feeding. Females that are starved from eclosion show a basal level of yolk protein gene transcription, which is rapidly increased when a complete diet is supplied. We show that the effect is not due to incorrect development of the fat body and is unlikely to be solely due to a general effect on protein synthesis. Later in development, cessation of feeding leads to selective inhibition of yolk protein synthesis and hence egg production. The effects of starvation can be partially overcome by 20-hydroxyecdysone, juvenile hormone, casein, amino acid mix or sucrose, but only a complete medium or live yeast brings about total recovery. Using yp1-Adh fusions (fusions of the promoter region of yp1 to the structural gene for Adh), the DNA sequence required for this diet-enhanced transcription has been located within an 890 bp fragment upstream of the yp1 gene. The insect hormones do not operate on this same DNA fragment.

Animals↗
PubMed1984

Quantitative structure-activity relationship of insect juvenile hormone mimetic compounds.

Juvenile hormone mimetic activities on Aedes aegypti (yellow-fever mosquito) and Tenebrio molitor (yellow mealworm) of compounds having (2E,4E)-3,7,11-trimethyl-2,4-dodecadienone structures were comparatively and quantitatively analyzed in terms of their physiochemical structural parameters and by regression analysis. They were structurally composed of three classes, ester and thiol ester derivatives, amides, and ketones, depending on the C1 substituents. The results indicated that the steric dimensions and the hydrophobicity of the whole molecule are important factors in governing the activity through these classes as well as through both insect species. The effects of the structure of the C1 and C11 substituents, the two ends of the chain molecule, are specific to the insect. The length along the bond axis of the C1 substituents is significant and the hydroxy and alkoxy functions attached to the C11 atom favor the activity on A. aegypti, whereas with T. molitor the width of the C1 substituents in the direction perpendicular to the bond axis is significant and the position-specific hydrophobicity of the C1 moiety enhances the activity. The activity is also affected differently by the compound types. The amide and ketone series of compounds are more active than the corresponding ester type of compounds on T. molitor, while the favorable types on A. aegypti are the ester and ketone derivatives. Correlation equations formulated for 85 active compounds on A. aegypti and 84 compounds on T. molitor led us to draw a hypothetical "mode of action" model for each species, which visualizes the overall similarity as well as the species differences of the interaction site or the receptor and may show the structural conditions necessary for activity.

Aedes↗