The contemporary methodology for growth models of organisms is based on continuous trajectories and thus it hinders us from modelling stepwise growth in crustacean populations. Growth models for fish are normally assumed to follow a continuous function, but a different type of model is needed for crustacean growth. Crustaceans must moult in order for them to grow. The growth of crustaceans is a...

IN three earlier papers (Wigglesworth, 1933, 1945, 1947a) the structure and deposition of the cuticle of Rhodnius proltxus have been described. The main conclusions reached were as follows. The epicuticle is a composite structure made up of four layers: (i) a 'cuticulin' layer composed of a condensed lipoprotein subsequently tanned by quinones; (ii) a layer of material rich in dihydroxyphenols;...

Ecdysteroids are steroid hormones involved in moulting and development of arthropods. Blood samples 32 individual bats eight insectivorous species were analysed for the presence ecdysteroids, using liquid chromatography mass spectrometry. Nine ecdysteroids detected. The spectrum these was similar bat which take their preferred food items from same insect order. blood-borne broader autumn than s...

Imaginal leg and wing discs obtained from late-third-instar Drosophila larvae were cultured in vitro in various concentrations of ecdysterone ranging from 10(-10) to 10(-5) M in order to test the effect of hormone concentration on evagination and cell differentiation. At the optimal concentration of 8 x 10(-8) M discs evaginated normally, secreted the pupal cuticle, underwent apolysis, differen...

Approximately 30 different closely related compounds possessing moulting hormone activity (ecdysones) have been isolated from plants, but such compounds are by no means universally distributed within the plant kingdom (Hikino & Hikino, 1970; Rees, 1971 ; Horn, 1971). They include compounds possessing C2,, CZ8 or CZ9 steroid skeletons, ecdysterone (Cz7) being probably the most widespread insect-...

Three cattle, which had been experimentally infected with Theileria parva lawrencei and maintained as carriers of the infection, were each infested simultaneously with clean nymphal Rhipicephalus appendiculatus and Rhipicephalus zambeziensis in ear bags on separate ears. After moulting, the ensuing adult ticks were fed on rabbits for 4 days and their salivary glands were examined for infective ...

The two brassinosteroids, 22 S,23 S-homobrassinolide and 22 S,23 S-homocastasterone are weak competitors of the binding of [3H]ponasterone A to the intracellular ecdysteroid receptor from the epithelial cell line from Chironomus tentans. The relative affinities to the ecdysteroid receptor are 0.001 for both brassinosteroids as compared to 20-OH-ecdysone and 0.1 in comparison to ecdysone. Both s...