Dissociation of Lipid Components and Reconstitution at – 75° C of Mg<Superscript>2+</Superscript> Dependent,Na<Superscript>+</Superscript> and K<Superscript>+</Superscript> Stimulated,Adenosine Triphosphatase in Rat Brain

MEMBRANE enzymes, because of their lipid content, are insoluble in water and usually solubilized as micelles in aqueous solution by detergents for biochemical study. Direct study of lipid components by means of organic liquids in which they dissolve leads at once to the denaturation of the enzyme. At temperatures appreciably colder than 0° C, however, organic solvents may leave enzymatic activity intact^1–3, making it possible to study enzyme reactions.     

INDUCTIVE CAPACITIES OF GLOMERULAR BASEMENT MEMBRANES AND DENTINE MATRIX

The inductive capacities of the basement membranes of calf kidney glomeruli and the dentine matrix of the incisors of 23-day rabbit fetuses were examined on the presumptive ectoderm of Triturus gastrulae. The basement membranes caused almost entirely neural induction and the dentine matrix caused mesodermal induction. These findings suggest that intercellular substances play an important role in the inductive effects of heterologous tissues.     

Pattern Regulation of the Leg Disc of the Fleshfly, Sarcophaga peregeina

A fate map of the hind leg disc of Sarcophaga peregrina was constructed by examining the adult structures of implanted disc fragments. The locations of presumptive adult structures in the disc were similar to those of fore leg disc of Drosophila and Sarcophaga ruficornis . However, the concentric borderlines of the segments could not be ascertained in the present case.
Pattern regulation of disc fragments was studied by culturing them either in adult females for several days or for 3 days in mature larvae placed on wet condition. Cultured disc fragments regenerated or duplicated as in Drosophila , with some exceptions. For instance, the region with a high density of positional values, the upper medial quarter, of the fore leg disc of Drosophila was not found. A characteristic difference in the rate of regeneration or duplication was observed in the implanted fragments, when cultured in larvae or adult hosts. This variable pattern regulation in larval and adult hosts could be due to different compositions of the hemolymph in which would healing of the implanted disc fragments takes place.     

Ecdysteroid Metabolism in Insects

SYNOPSIS. Remarkable development in ecdysone research has beenachieved during this decade in terms of organic chemistry, biochemistryand physiology, although the problems concerning the actionand behavior of ecdysteroids in target cells still remain tobe solved. To elucidate the dynamics of secretion, action andinactivation of ecdysone, the metabolic pathways for ecdysteroidshave been examined in several insect species and are summarizedhere. There may be at least three major inactivation processesfor ecdysone, namely, (i) catabolic degradation, (ii) conjugateformation and (iii) epimerization to 3-epi-ecdysteroids through3-dehydro compounds. Two means of regulation of the ecdysonetiter to ensure normal development of insects are seen in Sarcophaga:(1) Enhanced epimerization of 20-hydroxyecdysone at the prepupalstage resulting in a decreasing titer of biologically activeecdysteroids. (2) Reactivation of a conjugate at the onset ofadult development (a stage with an increasing titer of biologicallyactive ecdysteroids).     

Geographic variation in the incidence of pupal diapause in Asian and Oceanian species of the flesh fly Boettcherisca (Diptera: Sarcophagidae)

ABSTRACT. The incidence of pupal diapause was examined in nine species of the genus Boettcherisca Rohdendorf ( B.peregrina, B.javanica, B.nathani, B.septentrionalis, B. karnyi, B. koimani, B. timorensis, B. formosensis and B.invaria ) collected from various localities in East Asia and Oceanian islands.
Colonies of B.septenrionalis, B. nathani and B.peregrina obtained from temperate regions of Asia and those of B. formosensis and B.peregrina from the continental subtropics entered pupal diapause in response to photoperiod at 20C.
The incidence of pupal diapause showed a geographic gradient in B.peregrina. No photoperiodically induced diapause was observed in the other five species which are indigenous to the tropical or subtropical habitats.
Different species of Boettcherisca seem to have evolved their pupal diapause independently of one another as an ecophysiological mechanism which enabled those species to expand from the tropical to temperate region.