Sclerotization of mosquito cuticle

Summary The mode of sclerotization ofAedes aegypti pupal and adult cuticle was examined by employing biochemical and radioactive techniques. During larval-pupal metamorphosis, tyrosine is converted to tanning precursors and is incorporated into aryl-amino adducts and -crosslinks. The major hydrolysis product of -crosslinks in pupal cases is identified to be arterenone. Examination of tanning modes in five different mosquito species shows that the ratio of quinone to -sclerotization not only differs within the life stages of the insects, but also differs between species.Study supported by N.I.H. Grant ROI-AI-14753.     

Flavonoid profiles of certain species ofRhynchosia of the family Leguminosae (Fabaceae)

Summary A survey of seventy naturally occurring populations ofRhynchosia representing seven species of different subgenera revealed the occurrence of C-glycosides, O-glycosides, prenylated flavonoids and aglycones.Rhynchosia albiflora (R. cyanosperma) differs in gross morphological features and seed coat color and in its flavonoid composition from the other representative species ofRhynchosia.Acknowledgments. P. Ramachandraiah is grateful to U.G.C., New Delhi, for financial assistance.     

Ein spezieller Rhabdomerentyp im Fliegenauge

Summary The central rhabdomere in certain marginal ommatidia of the compound eyes of 20 species, representing 7 families of the flies, differs in its organization from the central rhabdomere of the neighbouring non-marginal ommatidia. Moreover, at least in the Tabanidae, Rhagionidae, and Syrphidae, this rhabdomere complex is composed of the interdigitating segments of the rhabdomere 7 and 8. The morphology and topography of this new type are described.     

Changes in the free amino acid pattern of haemolymph of the common indian scorpionPalamnaeus bengalensis during moulting

Summary Haemolymph ofPalamnaeus bengalensis contains normally 12 and during moulting up to 15 free amino acids, being in maximal number at the end of ecdysis. Aminoacidaemia is most pronounced during the pharate stage. Tyrosine appeared for tanning of the cuticle. Taurine and methionine were not present.Acknowledgment. The author is thankful to Dr.S. C. Shrivastava for valuable guidance and State C.S.I.R. (U.P.) for funds.     

Stabilisation of collagen by betel nut polyphenols as a mechanism in oral submucous fibrosis

Treatment of reconstituted collagen fibrils and pieces of rat dermis with the crude extract, purified tannins or (+)-catechin from betel nut (Areca catechu) increases their resistance to both human and bacterial collagenases in a concentration-dependent manner. These tanning agents may stabilise collagen in vivo following damage to the oral epithelium, and promote the sub-epithelial fibrosis which occurs in betel nut chewers.     

Stabilisation of collagen by betel nut polyphenols as a mechanism in oral submucous fibrosis

Summary Treatment of reconstituted collagen fibrils and pieces of rat dermis with the crude extract, purified tannins or (+)-catechin from betel nut (Areca catechu) increases their resistance to both human and bacterial collagenases in a concentration-dependent manner. These tanning agents may stabilise collagen in vivo following damage to the oral epithelium and promote the sub-epithelial fibrosis which occurs in betel nut chewers.     

3-OH-Kynurenine content and ommochrome formation in the developing compound eye ofEphestia kühniella

Summary The eye color ofEphestia kühniella is primarily determined by the ommochromes xanthommatin and ommin. The pigmentation, an important part of eye differentiation, occurs mainly during the pupal stage. Comparative studies on eye colour mutants indicate that a first step in ommochrome synthesis is the binding of the precursor 3-OH-kynurenine to developing pigment granules. Both xanthommatin and ommin are present from the early beginning of eye differentiation, and exhibit different developmental profiles.     

Reactivation of juvenile hormone synthesis in adult drones of the honey bee,Apis mellifera carnica

Juvenile hormone synthesis was measured by the corpora allata radiochemical assay in vitro. No hormone was produced during pupal stages, but soon after adult eclosion the corpora allata were reactived. The rate of juvenile hormone III synthesis increased until day 10 after emergence. Possible functions of juvenile hormone in adult drones are discussed.     

Suppression of pupal esterase activity in Aedes aegypti (Diptera: Culicidae) by an insect growth regulator.

Changes in non-specific esterases of Aedes aegypti were noted during pupal development. One esterase band was found to increase markedly within 3 h of pupation and this increase in activity was suppressed by prior treatment of larvae with an insect growth regulator, ZR 515. It is suggested that the esterase activity may help to reduce endogenous levels of juvenile hormone during metamorphosis and that the growth regulator may prevent this normal regulation.     

Ecdysteroids in vitro promote differentiation in the accessory glands of male mealworm beetles

Physiological peak doses of 20-hydroxyecdysone were added to organ cultures of young pupal accessory glands of male Tenebrio molitor. During subsequent culture in vitro or in vivo, the glands accumulated adult-specific antigens. Control organ cultures showed no such antigen accumulation. In this system, ecdysteroid controls not only cell cycles but also differentiation.     

Laboratory observations on pupae on the medflyCeratitis capitata (Wied.)

Summary Laboratory observations on pupae ofCeratitis capitata showed that most adult emergence took place in the morning between 06.00 and 09.00 h. Pupae succeeded to emerge when covered with sand up to a depth of 30 cm. It was not possible to differentiate between sexes by pupal weight.     

Karyotypes and nuclear DNA contents of Polypteridae (Osteichthyes)

Summary Calamoichthys calabaricus, Polypterus palmas, P. weeksii, P. delhezi andP. ornatipinnis have the same amount of DNA per erythrocyte nucleus. The karyotype ofP. weeksii has 38 chromosomes and differs from the karyotypes of the other species, all with 36 chromosomes, by a Robertsonian chromosomal rearrangement. The karyotype condition is regarded as derived for vertebrates.Research supported by the Division of Human Genetics, K.U. Leuven, Belgium and the UNAZA, campus Kinshasa, Zaire. The Department of Human Genetics, University of Amsterdam, Netherlands, provided facilities for cytophotometry.     

Two mechanisms in the biological clock ofPieris brassicae L.: an oscillator for diapause induction; an hour-glass for diapause termination

Summary Resonance experiments for photoperiodic termination of pupal diapause demonstrated thatPieris brassicae uses a night-measuring hour-glass mechanism. In previous work the same resonance technique for diapause induction revealed that photoperiodic time-measurement is a function of the circadian system. For the first time in a living organism it has been shown that the biological clock operates by means of an oscillator for photoperiodic onset of a phenomenon and according to an hour-glass system for photoperiodic termination.     

The influence of different host plants on some biological aspects ofHeliothis armigera (Hub.)

Summary The suitability of 6 different plants as natural food forHeliothis armigera was tested. The different biological aspects ofH. armigera were taken in consideration. Kidney bean pods and cotton plant leaves were the most successful host plants tested as they increased the pupal weight and the reproductive potential of the resulting moths, followed by lettuce, which decreased the larval duration remarkably.     

Amino acid composition and sequence of crinia-angiotensin,an angiotensin II-like endecapeptide from the skin of the Australian frogCrinia georgiana

Summary Methanol extracts of the skin of the Australian amphibianCrinia georgiana contain large amounts of crinia-angiotensin II, a new angiotensin II-like peptide. This differs sharply from the conventional octapeptide angiotensins II in having attached the tripeptide Ala-Pro-Gly- to the N-terminus, and having an Ile residue substituted for the Val residue at position 6 from the C-terminus. Small amounts of angiotensin-like peptides have been traced, by radioimmunoassay, in skin extracts of some otherCrinia species.Supported by grants from the Consiglio Nazionale delle Ricerche, Italy, and from the Ministry of Education, Japan.     

Temporal storage of kynurenine and 3-OH-kynurenine in the fat body of metamorphosingEphestia kühniella

Summary During the pharate pupal stage a massive accumulation of kynurenine and 3-OH-kynurenine is observed in the fat body ofEphestia kühniella. By injection it can be demonstrated that this organ is capable of sequestering at least 3-OH-kynurenine, the dominating tryptophan metabolite inEphestia. It is suggested that the fat body reduces a possibly harmfull excess of tryptophan metabolites at the beginning of metamorphosis. These sequestered metabolites provide a precursor depot for ommochrome synthesis in later development.     

Cholinergic control of extracardiac pulsations in insects

Summary The autonomic nerve system which controls extracardiac pulsations of hemolymph pressure appears to be quite susceptible to cholinesterase inhibitors (physostigmine, organophosphorus insecticides). In pupae ofTenebrio molitor L. andGalleria mellonella L., the treatment induced large peaks in hemolymph pressure (over 4 kPa). The peaks were repeated at more-or-less constant, 30-s intervals for several hours or days. Removal of the pupal brain neither affected extracardiac pulsations nor influenced the specific responses to the investigated drugs or insecticides.     

Growth and development of the American bollwormHeliothis armigera Hubn. under laboratory mass rearing conditions

Summary A kidney bean meal diet was the most satisfactory laboratory diet for the larvae of the American bollwormHeliothis armigera Hubn. Optimum rates of survival (63.5%) occurred and the larval growth was better than that of larvae reared on castor oil plant leaves. The pupal weight and the fecundity of the resulting adults were also much better than those on the control host plant.     

Tyrosine hydroxylase activity and tyrosine titers during cockroach metamorphosis

Summary Tyrosine hydroxylation (TH) to dopa in vivo in nymphs and pharate adults ofPeriplaneta americana was very low, but increased over 30-fold beginning at ecdysis. Free tyrosine increased in pharate, adults and peaked at ecdysis, whereas TH activity peaked 6 h later. Both TH activity and tyrosine titers declined the next 24 h as the cuticle tanned. TH appears to regulate tanning substrate biosynthesis in cockroaches.Contribution No. 81-294-j, Department of Entomology, Kansas Agricultural Experiment Station, Manhattan KS. Research supported in part by National Science Foundation grant No. PCM-8003859. I wish to thank Dr. M.A.J. Al-Izzi for assistance with the enzyme analyses.     

The alteration of juvenile hormone titre inSpodoptera litura (F.) due to a baculovirus infection

Summary The haemolymph juvenile hormone levels ofSpodoptera litura were remarkably low (540 Galleria units (GU)/ml) at the last larval moult as well as prior to pupation (194 GU/ml). During the last intermoult period this was 2600 GU/ml for a 24 h-period. On the other hand, the JH level in the haemolymph of NPV-infected last instar larvae was initially 1740 GU/ml but was maintained at 2400–2600 GU/ml during the next 48 h. Finally, the JH titre fell to 1393 GU/ml, but only prior to death. The failure of the diseased larvae to undergo the larval pupal moult is ascribed to the alteration of the JH titre in the haemolymph.