Herbert Röller

Purification and isolation of juvenile hormone and its action in lepidopteran larvae

Abstract : Conclusions: (1) The JH-active compound extracted from abdomina of adult male Cecropia is identical with the juvenile hormone produced by corpora allata. (2) The JHactive compound which we have isolated is the juvenile hormone. (3) Juvenile hormone is not farnesol, farnesal, farnesyl methyl ether, or any other compound previously tested for JH activity.

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

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.

On the biosynthesis of juvenile hormone in the adult Cecropia moth.

In adult males of the giant silk moth Hyalophora cecropia (L.) the amount of juvenile hormone (JH) extractable from the abdomens increases sharply between the first and fourth day of adult life; 4-8 day-old moths contain up to 6 μg. During the biosynthesis, L-methionine provides the ester methyl group of both JH and its lower homologue JH-II. It does not contribute to the formation of the carbon skeleton. Farnesol, farnesyl pyrophosphate, and propionate are not utilized. Mevalonate is extensively incorporated into trans,trans-farnesol, but not into the sesquiterpene-like hormone. This result indicates that JH is not synthesized via mevalonate in the adult moths. Label of 2-14C-acetate was recovered in both JH and farnesol; the incorporation rate, however, was very small. The label of JH was located in the carbon skeleton.

The Juvenile Hormones in Blood of Larvae and Adults of Manduca sexta (Joh.)

Abstract Juvenile Hormone, Manduca sexta The juvenile hormones (JH) in extracts of M anduca sexta blood were converted to 10-(2,4-di-chlorobenzoyloxy)-11-methoxy derivatives and quantitatively determined by gas chromatography with electron capture detection. Early IVth instar larvae contained 0.62 ng JH-I, 1.1 ng JH-II and 0.07 ng JH -III per ml blood. Early Vth instar larvae, and adult of both sexes contained the hormones in concentrations from 0 to 0.24 ng/ml blood. No hormone was detected in late Vth instar (wandering) larvae. The detection limit in our experiments was ≦ 0.003 ng/ml blood.

Isolation of Juvenile Hormone in Different Species

Following isolation (Roller et al., 1965; Roller et al., 1969), identification (Roller et al., 1967; Dahm et al., 1968), and the first synthesis (racemic form) of the juvenile hormone [JH (Dahm et al., 1967)] of the giant silk moth, Hyalophora cecropia, we started investigating the biosynthesis of the hormone. In order to [study this question successfully, our original purification procedure for JH has been refined, and the new method has been tested for the first time in Hyalophora gloveri [(Dahm and Roller, 1970) and Table 1]. Its efficiency was determined through addition of synthetic 2-14C JH to the crude oil, and the recovery of JH in all cases was found to be 50–60 per cent. The major loss of hormone occurs during the cold precipitation, when 30 per cent of the JH remains as part of the precipitate. The hormone can be recovered, only at the cost of a substantially decreased purification factor, by a change of the ratio of solvent and its amount. Precipitation at low temperature is an essential step in the process for isolation since this procedure eliminates lipoidal material that would interfere with the final separation of JH by gas chromatography.

Propionate as a Precursor of Juvenile Hormone in the Cecropia Moth

Abstract Juvenile Hormone, Biosynthesis, Cecropia Moth Adult 3-4 day old males of the giant silk moth H yalophora cecropia incorporate the label of [1-14C] propionate and [1-14C]butyrate in JH-I and JH-II. [1-14C]propionate is used for the bio synthesis of the hormones as an intact C3-unit. Three possible intermediates in the biosynthesis of JH-I-(E,E,Z)-7-ethyl-3,11-dimethyl-2,6,10-tridecatrienoic acid, its methyl ester, and the cor responding alcohol - were converted in low yields to the hormone. Methyl 7-ethyl-3,11-dimethyl-tridecanoate was not incorporated. Mevalonate applied to larvae before pupation was not used for the synthesis of a hypothetical JH-I precursor.

Biosynthesis and Degradation of Juvenile Hormone

The juvenile hormone [JH, Figure 1; (Roller et al., 1967; Dahm et al., 1968, 1967; Roller and Dahm, 1968)] and its lower homologue JH-II [Figure 2; (Meyer et al., 1968)] have basic structures typical of acyclic sesquiterpenes, for example, farnesol (Figure 3). The most significant differences, however, are the ethyl groups at C7 and C11 or C11, respectively. This substitution poses an intriguing biochemical problem because no natural mevalonate-derived compound of this kind has been found before. Consequently, investigations of the biosynthesis of the hormone cannot be based on precedence.