Malarial parasites complete sporogony in axenic mosquitoes

Summary To obtain sporogonic stages of malaria free from microbial contaminants for in vitro studies,Anopheles stephensi were reared under sterile conditions using a mosquito cell line as larval food. The adult females, kept in sterile humidified containers and allowed to engorge on parasitemic hamsters, supported the sporogonic development of the rodent malarial parasitePlasmodium berghei. In 10 experiments, the proportion of infected mosquitoes varied from 0 to 92%, and the geometric mean number of oocysts per female mosquito from 2.5 to 58,6, with a range of 1 to 548. The average number of salivary gland sporozoites per infected mosquito was determined by direct sporozoite counts in the pooled homogenate of the thoraces of all female mosquitoes. In five experiments, it varied from 2.7×10³ to 9.0×10³. The sterile sporozoites, harvested on day 19 or 20 after the infective blood meal, were as infective for rodents as nonsterile ones.Supported in part by Public Health Service research grant AI 18345 from the National Institute of Allergy and Infectious Diseases, by a grant from the Agency of International Development DSPE-5542-G-SS-3042-00, and by a Charles and Johanna Busch award.     

NADP-isocitric dehydrogenase of gerbil adrenal mitochondria: support of steroid hydroxylation

In gerbil adrenal cortex the activity of intramitochondrial NADP-linked isocitric dehydrogenase (IDH) is up to 10-fold greater than the NAD-linked IDH. The NADP-IDH, apparent Km 0.58 mM, Vmax 280 nmoles/min/mg mitochondrial protein, appears to be the major source of reducing equivalents to support adrenal mitochondrial steroid 11B- and 19-hydroxylation in this species.     

Beta-adrenergic-stimulated adenylate cyclase activity in normal and EBV-transformed lymphocytes

Summary Beta-adrenergic-associated cyclic AMP accumulation was studied in intact lymphocytes before and after transformation with Epstein-Barr virus into immortal cell lines. Although a marked reduction in isoproterenol-stimulated cyclic AMP synthesis was observed in transformed cells, forskolin-stimulated cyclic AMP accumulation was preserved. A parallel loss of¹²⁵-iodocyanopindolol binding sites suggests that the reduction in beta-adrenergic-stimulated AMP synthesis is due to receptor down regulation.     

IgG purification to measure the level of an iodinated thyroglobulin peptide, the 3,5,3',5' tetraiodo-l-tyrosyl-l-tyrosine in human serum

Antibodies reacting with 3,5,3',5' tetraiodo-l-tyrosyl-l-tyrosine (I2Tyr-I2Tyr) were elicited in rabbits by immunization with an oxidized yeast conjugate coupled with I2Tyr-I2Tyr. Ion-exchange chromatography was used to purify immunoglobulins, in order to improve the specificity in measurement of I2Tyr-I2Tyr level in patient serum. IgG binding capacity versus I2Tyr-I2Tyr was considerably increased after immunoglobulin purification.     

Injection of a soluble sperm fraction into sea-urchin eggs triggers the cortical reaction

Fertilization membranes form around unfertilized sea-urchin eggs after microinjection of a soluble spermatozoa fraction isosmotic with seawater. This demonstrates that the spermatozoon contains a chemical that triggers an increase in cytosolic calcium, leading to exocytosis of cortical granules. It also demonstrates that the triggering mechanism does not require an externally-activated egg-membrane process. Further experiments show that the chemical trigger is not calcium.     

A non-peroxide norsesterterpene from a marine spongeHyrtios erecta

Summary A new norsesterterpene, hyrtial4, and known sesterterpenes,1–3, have been isolated from an anti-inflammatory active crude extract of the spongeHyrtios erecta.This sponge,Hyrtios (Heteronema) erecta Keller 1889, collected in 1980/81, from Tonga was extremely abundant in the Vava'u Is. Group.We thank Prof. R. Jacobs and his research group at UCSB for this data.     

Protein folding: concepts and perspectives

In this review, the main concepts of protein folding, as deduced from both theoretical and experimental in vitro studies, are presented. The thermodynamic aspects from Anfinsen's postulate, Levinthal's paradox to the concept of folding funnel as proposed by Wolynes and coworkers are described. Concerning the folding pathway(s), particular attention is brought to bear on the early steps that initiate the process in the light of the results of the fast and even ultrafast techniques presently being used. The role of structural domains as folding units is discussed. Last, from the recent studies, it can be concluded that the main rules deduced from the in vitro folding studies are valid for the folding of a nascent polypeptide chain in vivo.     

Interpreting animal wall-following behavior

Summary Using computer simulations and behavioral experiments with the American cockroach, we found that active vs passive (barrier-directed) wall-following can be readily distinguished and quantified by incorporating a range of convex curves into test arenas. Although previously considered strongly thigmotactic, more than 50% of running American cockroaches depart convex curves with diameters, less than 1 m. A new framework for evaluating wall-following behaviors is presented.     

The AA and ANA rat lines, selected for differences in voluntary alcohol consumption

The offspring of rats that voluntarily select larger quantities of alcohol are heavier consumers of alcohol than the offspring of rats that tend to avoid it. Such selective breeding, repeated over many generations, was used to develop the AA (Alko, Alcohol) line of rats which prefer 10% alcohol to water, and the ANA (Alko, Non-Alcohol) line of rats which choose water to the virtual exclusion of alcohol. In addition to demonstrating the likely role of genetic factors in alcohol consumption, these lines have been used to find behavioral, metabolic, and neurochemical correlates of differential alcohol intake. Some of the line differences that have been found involve the reinforcing effects of ethanol, the changes in consumption produced by alcohol deprivation and nutritional factors, the behavioral and adrenal monoamine reactions to mild stress, the development of tolerance, the accumulation of acetaldehyde during ethanol metabolism, and the brain levels of serotonin. It is hoped that these studies will lead to a better understanding of the genetically-determined mechanisms that influence the selection of alcohol.     

Ultrastructural localisation of substance P and choline acetyltransferase in endothelial cells of rat coronary artery and release of substance P and acetylcholine during hypoxia

Substance P and choline acetyltransferase have been localised in a small proportion of endothelial cells of rat coronary arteries using electron microscopic immunocytochemistry. During a hypoxic period of 1 min, coronary vasodilatation was produced in the Langendorff heart preparation and increased levels of substance P and acetylcholine were released into the perfusate. The possibility that these substances are released from endothelial cells during hypoxia and contribute to the hyperaemic response is discussed.