Heinz Rembold

Biologically active substances in royal jelly.

Publisher Summary This chapter discusses biologically active substances in royal jelly. The composition of royal jelly must be compared with that of worker jelly to determine whether there are qualitative and quantitative differences in these foods. Such analyses would serve as a basis for the development of partial or complete synthetic larval foods. Worker jelly is higher in protein but lower in sugar than royal jelly. The values for royal jelly are practically unchanged in the 72–96 hour age group, while the sugar content of worker jelly is substantially higher, and the protein portion is lower, obviously because of the addition of honey. An interesting structural similarity of the royal jelly acid is found in the case of the so-called queen substance, a pheromone secreted by the queen, which inhibits queen cell construction. The remarkable specific biological activity limited to biopterin, and its increased concentration in royal jelly, seems to indicate that this pterin is of importance in the development of honey bee larvae. Ion-exchange chromatography on Dowex 1-X8, with the additional purification of the resulting fractions on cellulose exchangers, permits the isolation of even small traces of pterin from biological material.

Catabolism of pteridine cofactors: I. Properties and metabolism in rat liver homogenates of tetrahydrobioterin and tetrahydroneopterin

Abstract The stability of tetrahydropterins to oxidation has been investigated. Oxidation products, pterin and dihydroxanthopterin, of tetrahydrobiopterin were separated and identified. The cleavage of the side chain of tetrahydroneopterin is shown to be an irreversible reaction coupled to an oxidative process. The side chain is split off as glyceraldehyde. Incubation mixtures of labeled tetrahydrobiopterin in rat liver homogenates have been analyzed using chromatographic procedures, whic allow the balances of all pteridine metabolites to be established. Formation of the acidic products, lumazine, 6-hydroxylumazine and 6,7-dihydroxylumazine, from tetrahydrobiopterin in these homogenates is ascribed to enzymatic reactions which are characterized under various conditions. The occurrence of some pteridines usually present in biological extracts is discussed in the light of these findings.

Catabolism of pteridine cofactors. II. A specific pterin deaminase in rat liver.

A specific pterin deaminase has been detected in rat liver. The enzyme was purified 23-fold. During its purification, guanine deaminase (EC 3.5.4.3) activity of the protein was increased 39-fold. Evidence is given which establishes the nonidentity of pterin deaminase and guanine deaminase: changes in the ratio of their activities during preparation; differences in stability during storage and inhibition by CN− and by azaguanine and guanine; differences in the pH maxima and in the distribution of enzyme activities in various organisms. The reaction maximum is at pH 6.5 and Km is 30 μM. The enzyme specifically deaminates pterin, isoxanthopterin and tetrahydropterin. Xanthopterin, biopterin, neopterin, pterin-6-carboxylic acid, and 6-hydroxymethylpterin are not deaminated. In the honeybee (Apis mellifica), pterin deaminase activity has also been detected. The highest activity has been found in 4-day-old larvae.

Catabolism of pteridine cofactors III. On the introduction of an oxygen function into position 6 of the pteridine ring

Abstract The formation of 6-hydroxylumazine from tetrahydrolumazine in rat liver homogenates shows the same characteristics as already described for tetrahydrobiopterin and tetrahydroneopterin. By spectrophotometric methods, 7,8-dihydrolumazine is shown to be an intermediate in the aerobic oxidation of tetrahydrolumazine, 7,8-Dihydrolumazine is the substrate for xanthine oxidase. The kinetics of the enzyme-catalyzed formation of 7,8-dihydro-6-hydroxylumazine was measured. If the reaction is started with tetrahydrolumazine, xanthine oxidase catalysis is the rate-limiting step in the reaction sequence. The enzymic reaction shows maximal activity at pH 7.9 and a Km = 4.4·10−4 M for dihydrolumazine. The conversion of 7,8-dihydrolumazine to 7,8-dihydro-6-hydroxylumazine is also effected by a nonenzymic reaction which can be distinguished clearly from the enzymic one. In the pterin series an analogous reaction sequence is followed which results in the formation of 7,8-dihydroxanthopterin and xanthopterin from tetrahydroneopterin and tetrahydrofolic acid. The catabolism of pteridine cofactors is discussed and summarized in a reaction scheme.

Influence of the braconid Glyptapanteles liparidis on the juvenile hormone titer of its larval host, the gypsy moth, Lymantria dispar

The increase in the juvenile hormone (JH) III titer in the hemolymph of Lymantria dispar larvae that were parasitized by the endoparasitoid braconid, Glyptapanteles liparidis, during the hosts premolt to third instar, coincided with the molt of the parasitoid larvae to the second instar between day 5 and 7 of the fourth host instar. It reached a maximum mean value of 89 pmol/ml on day 7 of the fifth instar while it remained below 1 pmol/ml in unparasitized larvae. Only newly molted fifth instar hosts showed a low JH III titer similar to that of the unparasitized larvae. JH II, which is the predominant JH homologue in unparasitized gypsy moth larvae, also increased relative to controls in the last two samples (days 7 and 9) from parasitized fourth and fifth instars. Compared to unparasitized larvae, a generally reduced activity of JH esterase (JHE) was found in parasitized larvae throughout both larval stages. The reduction in enzyme activity at the beginning and at the end of each instar, when the JHE activity in unparasitized larvae was high, may be in part responsible for the increased JH II and JH III titers in parasitized larvae. Ester hydrolysis was the only pathway of JH metabolism in the hemolymph of unparasitized and parasitized gypsy moth larvae as detected by chromatographic assays.

Entwicklungsabhängige mitochondriale enzymaktivitäten bei den kasten der honigbiene

Abstract Development-dependent mitochondrial enzyme activities in castes of the honey bee Mitochondria of queen and worker honey bees were isolated and purified in various developmental stages as follows. The mitochondrial preparation free of sarcosomes, lysosomes and microsomes, was obtained by centrifugation of a crude mitochondrial fraction in a slight gradient of sucrose containing a steep gradient of stractan AF/2 (Meyhall). The fractionated cell particles were characterized by their contents of protein and RNA, and their activities of acid phosphatase, acid ribonuclease, uricase and succinate dehydrogenase, respectively. After gradient centrifugation, three bands corresponding to the maxima of the protein content were observed in the sedimentation pattern. The middle band contained mitochondria. In the larvae and white-eyed pupae the band was separated further into lighter and heavier fractions. The quantity of the mitochondria in the queen is more than 2-fold higher than that of the worker throughout the developmental stages. When succinic acid, α-glycerophosphoric acid and butyric acid were used as substrates of the oxidation systems, the mitochondria of both castes demonstrated the maximal activity in the 5-day-old larva. The activities of the oxidation systems in the queen were substantially higher than those in the worker, particularly in the larval stages. It was further shown by the difference spectra of mitochondria, that both castes were deficient in cytochrome c in the early developmental stages. The worker larva contained quantitatively less cytochrome c and cytochrome oxidase than the queen larva. It was concluded from these results, that the production of mitochondria in the queen is quantitatively and qualitatively stimulated and the cytochrome system is sufficiently built up by the influence of the determining substance contained in royal jelly. Because of the low content of mitochondria in addition to the diminished activity of the respiratory chain, the worker larva showed an oxygen consumption half as large as that of the queen larva.

Catabolism of pteridine cofactors: IV. In vivo catabolism of reduced pterins in rats

By measuring excreted radioactivity the retention of 14C-labeled tetrahydropterins (biopterin, d-erythro- and l-erythro-nepterin, 6-hydroxymethylpterin) and of 7,8-dihydro-6-hydroxymethylpterin has been followed after intraperitoneal injection into rats, given at a concentration of 10 mg/kg. More than 70% of the reduced 6-polyhydroxyalkylpterins are retained. In the urine 6-hydroxylumazine and xanthopterin are found as the main degradation products of all the reduced pterins. No radioactivity was incorporated into biopterin, isolated from the urine after injection of either tetrahydroneopterin, 7,8-dihydro- or tetrahydro-6-hydroxymethylpterin.

Analytische und histologische Untersuchungen der Kopf- und Thoraxdrüsen bei der Honigbiene Apis mellifica

Bei Ammenbienen tritt eine Veränderung des Biopterin- und Pantothensäuregehaltes durch äußere Einflüsse nur in den Mandibulardrüsen auf. Die für Weisel- und Arbeiterfuttersaft charakteristischen heterocyclischen Verbindungen werden nur in den Pharyngealdrüsen gefunden. Dieser Befund und der histo-autoradiographische Nachweis des gerichteten Einbaus von [2-14C] Biopterin sprechen für eine Sekretion des Arbeiterfuttersaftes als Grundfutter aus den Pharyngealdrüsen. Vergleichend histologische Untersuchungen zeigen bei Ammenbienen des Weiselzuchtvolkes eine Vergrößerung der Hinterkopfdrüsen und Vermehrung der profunden Postgenaldrüsen-Zellen. Das Zusammenwirken der verschiedenen Drüsen bei der Futtersaftbildung wird diskutiert.

Über die gerichtete Aufnahme des Biopterins im Organismus I.

C14 labelled Biopterin and Neopterin, when fed to larval stages of Queen and Worker bees, behave similarly and are incorporated into different organs. During metamorphosis and imaginal development, the accumulation of the radioactive pterins is found in places of high metabolic activity such as the eyes, wings, legs. They are also found in the tracheal epithelium, in the wing muscles and the ovaries. In tissues of high cellular activity the radioactivity is found in the nuclei. The concentration of the administered labelled Biopterin and Neopterin into the imaginal cuticle at the time of sclerotization and pigmentation, as well as their directed uptake by the peripheral ganglion sheath of the central nervous system points to the functional importance of these pterins as cofactors of phenylalanine hydroxylase and respectively of tryptophane hydroxylase in insects.