Esterase D polymorphism in a French-Canadian population

Summary Red blood cell esterase D (ESD) polymorphism was studied in a French-Canadian population from Quebec city, Canada, by means of high voltage electrophoresis on agarose gel followed, in heterozygotes for ESD1, by IEF to reveal the possible allele ESD^*5. Frequencies of the ESD alleles in 904 unrelated individuals were ESD^*1: 0.888, EDS^*2: 0.095 and ESD^*5: 0.017. The segregation pattern observed in 275 families confirmed a Mendelian inheritance of three autosomal alleles.     

Production and secretion of C-19 steroids by rat and guinea pig adrenals

The concentrations of C-19 steroids were measured in guinea pig and rat adrenals before and after castration as well as after stimulation with adrenocorticotropin hormone (ACTH). Characterization of adrenal C-19 steroids was also carried out by isolation with high-performance liquid chromatography and gas chromatography/mass spectrometry (GC/MS). From radioimmunoassay (RIA) data, androstenedione (4-DIONE) and 11 beta hydroxyandrostenedione (11 beta-DIONE) were the major C-19 steroids found in guinea pig adrenals, and castration induced a decrease of 4-DIONE levels only while all other C-19 steroids remained unchanged. In rat adrenals, the major C-19 steroids were 4-DIONE and testosterone, and they were also markedly inhibited after castration. With the exception of 11 beta-DIONE, all other C-19 steroids in circulation were eliminated after castration in both animals species. After ACTH administration in the guinea pig, adrenal 4-DIONE and 11 beta-DIONE levels were markedly stimulated, while an increase of only 11 beta-DIONE was observed in plasma. In the rat, ACTH had a small stimulatory effect on adrenal 52-androstane-3 alpha, 17 beta-diol (3 alpha-DIOL) and plasma 11 beta-DIONE levels. Analysis of guinea pig adrenal steroids by GC/MS confirmed the presence of C-19 steroids in adrenals (namely, 4-DIONE and 11 beta-DIONE) while, in the rat, this could not be confirmed. Our data indicate that production of C-19 steroids occurs in guinea pig adrenals, and 11 beta-DIONE is the major C-19 steroid as well as the only C-19 steroid secreted into the circulation. In the rat, the production of C-19 steroids detected by RIA is not supported by GC/MS data.     

Localization of mating behavior of releasedBactrocera dorsalis flies on host fruit in an orchard

Oriental fruit flies,Bactrocera dorsalis, cultured in the laboratory for six generations, were released when 12–14 days old in an orchard of nonfruiting host trees that were furnished with either food and water, nonpunctured host fruit, punctured host fruit, or no resources. Nearly all flies of both sexes, all sexual behavior of males, and all mating pairs were observed on trees with fruit. Moreover, on trees with fruit, nearly all flies of both sexes, nearly all sexual behavior of males, and nearly all mating pairs occurred on the fruit itself rather than on the foliage or branches. In a subsequent test, both sexes were found to be strongly attracted to the odor of host fruit. For a polyphagous species of a tropical tephritid, these findings are the first to show a high level of male aggregation and a high amount of male sexual behavior on the fruit of host trees. Findings are discussed in relation to current knowledge of tephritid mating behavior. An additional quality-control test for laboratory cultured males used in the sterile insect technique of fly management is recommended.     

Membrane fatty acid composition of tissues is related to body mass of mammals

Phospholipids were extracted from tissues (heart, skeletal muscle, kidney cortex, liver and brain) of mammals representing a 9,000-fold range in body mass (mouse, rat, rabbit, sheep and cattle) and their fatty acid composition was determined. In heart, skeletal muscle and kidney cortex, there were significant allometric decreases in the Unsaturation Index (UI; average number of double bonds per 100 fatty acid molecules) with increasing body mass. There were significant inverse allometric relationships between body mass and the proportion of docosahexaenoic acid (2263) in heart and skeletal muscle. In heart, skeletal muscle and kidney cortex, larger mammals also had shorter fatty acid chains in their phospholipids and a higher proportion of monounsaturates. In liver, smaller mammals had a higher UI than larger mammals (except the rabbit, which had the lowest UI and very low proportions of 3 fatty acids). The brain of all mammals maintained a high UI with similar levels of polyunsaturated fatty acids, especially 2263. Our results suggest that in heart, skeletal muscle and kidney cortex the activity of the elongases and desaturases are reduced in large mammals compared to small mammals. The allometric trends in membrane composition may be involved in modifying membrane permeability. It is proposed that the elevated degree of polyunsaturation in the membranes of several tissues from small mammals is related to their higher metabolic activity.This work was supported by an Australian Commonwealth Postgraduate Research Scholarship from the University of Wollongong to P. Couture and by a grant from the Australian Research Council to A.J. Hulbert. We wish to thank Voytek Mantaj for technical assistance.     

Steroid glucuronides: Human circulatory levels and formation by LNCaP cells

We studied the relationship between circulating androsterone glucuronide, androstane-3,17β-diol glucuronide and androstane-3β,17β-diol glucuronide concentrations and adrenal as well as testicular C-19 steroids in men. Among the three 5-reduced steroid glucuronides, androsterone glucuronide is the predominant C-19 steroid measured in plasma and its levels are markedly elevated compared to those of the non-conjugated steroid. The marked rise in testosterone during puberty was strongly correlated with the increase in both androsterone glucuronide and androstane-3,17β-diol glucuronide, thus suggesting that testicular C-19 steroids are the main precursors of the steroid glucuronides. We also found that the presence of testicular androgen in plasma contributes to approx. 70% of plasma androsterone glucuronide and androstane-3,17β-diol glucuronide. Our data suggest that the adrenal C-19 steroids remaining in circulation after castration in men are converted into potent androgen which are then glucuronidated by UDP-glucuronyltransferase. We also demonstrated that the human prostate cell line LNCaP is capable of converting to a large extent androstenedione into androsterone glucuronide. Our data further confirm that glucuronidation is a major pathway of steroid metabolism in steroid target tissues.     

K+/H+ exchange in yeast mitochondria: sensitivity to inhibitors, solubilization and reconstitution of the activity in proteoliposomes.

The K+/H+ exchange activity of the inner mitochondrial membrane was investigated in the yeast Saccharomyces cerevisiae. Swelling experiments in potassium acetate indicated that the K+/H+ exchange was active without any additional treatment after the mitochondria isolation, such as a Mg2+ depletion. As in mammalian mitochondria, the activity of yeast mitochondria was stimulated by increasing pH and was inhibited by the amphiphilic amines quinine and propranolol and by the carboxyl reagent dicyclohexylcarbodiimide. However, the activity was poorly inhibited by Mg2+ and consequently was only slightly stimulated by the Mg2+/H+ exchanger A23187. On the other hand, Zn2+ was very efficient for inhibiting the exchange and consequently the activity was strongly stimulated by the permeant metal-chelator o-phenanthroline. The [86Rb]Rb+ accumulation in mitochondria and mitoplasts was only partially inhibited by quinine and propranolol suggesting that part of the accumulation monitored under these conditions was due to cation leak through the inner membrane together with adsorption on the membrane. The DCCD-sensitive activity could be reconstituted from mitochondria and from mitoplasts solubilized with Triton X-100; this activity, measured by [86Rb]Rb+ accumulation, was quinine- and propranolol-sensitive. A spectrophotometric method, based on the capacity of negatively charged proteoliposomes to swell, was then developed in order to continuously follow the reconstituted activity.     

A microfluorometric method for alkaline phosphatase: Application to the various segments of the nephron

A microtechnique has been developed for the measurement of alkaline phosphatase in minute amounts of renal tissue. This microtechnique utilizes the known fluorescent property of 4-methylumbelliferyl phosphate following enzymatic hydrolysis. The reaction is sensitive and reproducible and is inhibited by l-bromotetramisole, a specific alkaline phosphatase inhibitor. The microdetermination of alkaline phosphatase activity in the various segments of the mouse nephron allowed the localization of the enzyme in the glomeruli, and in the proximal convoluted tubule where the activity progressively decreases from the capsule of Bowman to the more distal segments. The enzyme was absent from the pars recta or S3 and from the rest of the nephron. This technique is applicable to very small amounts (0.1 μg of protein) of any tissue containing alkaline phosphatase.     

Structure of T4 polyheads: II. A pathway of polyhead transformations as a model for T4 capsid maturation

We have studied the aberrant tubular polyheads of bacteriophages T4D and T2L as a model system for capsid maturation. Six different types of polyhead surface lattice morphology, and the corresponding protein compositions are reported and discussed. Using in vitro systems to induce transformations between particular polyhead types, we have deduced that the structural classes represent successive points in a transitional pathway. In the first step, coarse polyheads (analogous to the prohead τ-particle) are proteolytically cleaved by a phagecoded protease, a fragment of the gene 21 product. This cleavage of P23 to P23¹ induces a co-operative lattice transformation in the protein of the surface shell, to a conformation equivalent to that of T2L giant phage capsids. These polyheads (derived either from T4 or T2L lysates) can accept further T4-coded proteins. In doing so, they pass through intermediate structural states, eventually reaching an end point whose unit cell morphology is indistinguishable from that of the giant T4 capsids. At least one protein (called soc (Ishii & Yanagida, 1975)) is bound stoichiometrically to P23¹ in the end-state conformation. The simulation of several aspects of capsid maturation (cleavage of P23 to P23¹, stabilization, and lattice expansion) in the polyhead pathway suggest that it parallels the major events of phage T-even capsid maturation, decoupled from any involvement of DNA packaging.