scholarly journals The influence of substrate concentrations on the rate of insect juvenile hormone biosynthesis by corpora allata of the desert locust in vitro

1974 ◽  
Vol 144 (1) ◽  
pp. 107-113 ◽  
Author(s):  
Stephen S. Tobe ◽  
Grahame E. Pratt
Keyword(s):  
Juvenile Hormone ◽  
Schistocerca Gregaria ◽  
Corpora Allata ◽  
Synthetic Activity ◽  
Methyl Farnesoate ◽  
Physiological Concentration ◽  
Juvenile Hormone Biosynthesis ◽  
Hormone Biosynthesis ◽  
Influence Of Substrate

The rate at which isolated corpora allata of adult female Schistocerca gregaria incorporate [3H]farnesenic acid and [14C]methionine into C16juvenile hormone in vitro was examined at different concentrations of farnesenic acid, methionine, O2 and H+ ions. Maximum juvenile hormone biosynthesis is obtained at a farnesenic acid concentration of 20μm. The range of optimum l-methionine concentrations (0.1–0.4mm) encompasses the physiological concentration of this substrate in the haemolymph. Hormone biosynthesis is dependent on O2, but is not stimulated by hyperbaric oxygen tension. The glands had a maximum synthetic activity at pH8.0, but their activity was more reproducible in the the physiological range pH7.0–7.5. At pH6.5 and less, the synthetic ability was considerably decreased. The relative incorporations of the labelled substrates into methyl farnesoate and C16 juvenile hormone indicate that [3H]farnesenic acid comes into isotopic equilibrium within the gland more rapidly than [14C]methionine. The incorporations into methyl farnesoate become stoicheiometric after 20min incubation and into C16 juvenile hormone after a further 10min. Labelled juvenile hormone is detectable after 10min incubation and the rate of incorporation is constant for up to 4h. It is proposed that the described method may be usefully employed to assess the physiological changes in the enzymic competence of the glands to effect the last two stages in C16 juvenile hormone biosynthesis.

Juvenile hormone biosynthesis by the corpora allata of the male desert locust, Schistocerca gregaria, during sexual maturation

1978 ◽  
Vol 56 (10) ◽  
pp. 2097-2102 ◽  
Author(s):  
L. I. Avruch ◽  
S. S. Tobe
Keyword(s):  
Juvenile Hormone ◽  
Sexual Maturation ◽  
Time Course ◽  
Schistocerca Gregaria ◽  
Dry Weight ◽  
Corpora Allata ◽  
Gas Liquid Chromatography ◽  
Juvenile Hormone Biosynthesis ◽  
Hormone Biosynthesis

The time course of release of C16 juvenile hormone (JH III) from isolated corpora allata (CA) of male Schistocerca gregaria was followed at selected times during sexual maturation. The rates of JH release over an 8-h incubation period were observed to be directly related to the age of the animals: CA from younger animals showed low rates of release (days 5 and 8) whereas CA from older animals showed intermediate to high rates of release (days 12–13). The mean rate of JH release is linear for at least 4 h. The only biosynthesized JH which could be detected in the incubation medium by radio gas–liquid chromatography was C16JH.The dry weight of the accessory reproductive glands (ARG) was also followed during the period of sexual maturation. This increased rapidly between days 10 and 15 and leveled off thereafter. The biosynthesis of C16JH, as determined by a radiochemical assay in vitro, also increased during this period, suggesting a functional relationship between synthesis of ARG secretion and JH.

Increased juvenile hormone synthesis and decreased fertility in aging Schistocerca gregaria

1981 ◽  
Vol 59 (9) ◽  
pp. 1744-1748 ◽  
Author(s):  
H. S. Injeyan ◽  
J. F. Dale ◽  
S. S. Tobe
Keyword(s):  
Juvenile Hormone ◽  
Schistocerca Gregaria ◽  
Corpora Allata ◽  
Synthetic Activity ◽  
Hormone Synthesis ◽  
Young Females ◽  
Old Females

The fertility of aging Schistocerca gregaria females of both solitary and gregarious phases is markedly reduced in comparison with that of young females. Examination of eggs (from both young and aging females) maintained in vitro revealed that the decreased fertility of aging females of both phases could be attributed to a decrease in viability of eggs. This, in turn, was found to be in large part due to an increase in the proportion of embryos showing inhibited development. The proportion of inhibited embryos, in pods from young and old females, respectively, increased from 5 to 42% for gregarious animals and from 3 to 38% for solitary animals. Inhibition was found to occur at all stages from blastokinesis to ecdysis of the provisional cuticle. These morphogenetic aberrations were very similar to those obtained after treatment of S. gregaria eggs with exogenous juvenile hormone (JH). Investigation of the JH synthetic activity of corpora allata from aging females of each phase revealed a marked increase in the rates of JH synthesis in comparison with those of young females of the same phase. Furthermore, injection of JH into young females increased the proportion of embryos showing inhibited development from 7% (in control females) to 30% (in JH-treated females). These results suggest a possible correlation between reduced viability of eggs and high rates of JH synthesis in aging S. gregaria of both phases.

Stimulation of Juvenile Hormone Biosynthesis in vitro by Locust Allatotropin

1983 ◽  
Vol 38 (9-10) ◽  
pp. 856-858 ◽  
Author(s):  
Hans-Joerg Ferenz ◽  
Ingrid Diehl
Keyword(s):  
Juvenile Hormone ◽  
Locusta Migratoria ◽  
Corpus Allatum ◽  
Corpora Allata ◽  
Biosynthetic Activity ◽  
Hormone Synthesis ◽  
Heat Stable ◽  
Juvenile Hormone Biosynthesis ◽  
Hormone Biosynthesis

Abstract In Locusta migratoria the gonotrophic cycles are regulated by juvenile hormone. The cyclical changes of juvenile hormone synthesis in locust corpora allata seem to be regulated by a neuro-hormonal factor. Such an allatotropin could be extracted from corpora cardiaca and brains of Locusta migratoria. It is a small pronase-sensitive and heat-stable peptide. Extract of one corpus cardiacum stimulates corpus allatum biosynthetic activity in vitro 5 to 20-fold.

On the Specificity of Juvenile Hormone Biosynthesis in the Male Cecropia Moth

1981 ◽  
Vol 36 (7-8) ◽  
pp. 579-585 ◽  
Author(s):  
Martin G. Peter ◽  
Paul D. Shirk ◽  
Karl H. Dahm ◽  
Herbert Roller
Keyword(s):  
Juvenile Hormone ◽  
Enzyme System ◽  
Reaction Rates ◽  
Corpora Allata ◽  
Low Molecular Weight ◽  
Methyltransferase Activity ◽  
Accessory Sex Glands ◽  
Juvenile Hormone Biosynthesis ◽  
Hormone Biosynthesis ◽  
Natural Enantiomer

Abstract The accessory sex glands (ASG) of adult male Cecropia contain an enzyme that methylates juvenile hormone acids (JH-acids) in the presence of S-adenosyl-L-methionine (SAM). The methyltransferase is highly specific. The reaction rates decrease in the order JH-I-acid, JH-II-acid and JH-III-acid; in each case the natural enantiomer is esterified predominantly. Methyltrans­ ferase activity with the same substrate specificity was also demonstrated in adult female corpora allata (CA). Male CA have only marginal methyltransferase activity. The CA of male H. cecropia contain substantial amounts of JH-I-acid and JH-II-acid (minimum: 5 pmol/pair). When kept in organ culture, they release JH-acids into the medium. Radiolabeled propionate and mevalonate are incorporated efficiently into the carbon skeletons of the JH-acids. The enzyme system performing these transformations cannot be forced to produce JH-III-acid even in the presence of high mevalonate concentrations, though homomevalonate may enhance biosynthesis of JH-I-acid and JH-II-acid more than tenfold. It becomes evident that the regulation of JH titer balances with regard to the homologous structures during insect development is not merely a question of the availability of low molecular weight precursors, but in addition that of highly specific enzymes acting as regulatory entities in the later steps of the biosynthetic sequence.

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