The effect of X-rays and EMS on the behavior of the transposing element,TE98, inDrosophila melanogaster

Summary The sensitivity of TE98 (carryingw ^+R andrst ⁺) to X-rays does not differ significantly from the mutability ofcurled andkarmoisin loci. In addition no spontaneous mutants of TE98 were recovered, indicating its extreme stability. On the effect of EMS nowhite mutants were found supporting the view that thew ⁺ gene of TE98 is duplicated.     

Effects of the virulence plasmid ColV, I-K94 on the sensitivity of Escherichia coli to putative environmental inhibitory agents

Derivatives of Escherichia coli carrying the virulence plasmid, ColV, I-K94 were more resistant than the ColV- parents to phage Mel but were more sensitive to the hydrophobic inhibitors deoxycholate, erythromycin and lysozyme. The basis for these changes in sensitivity has been examined in ColV+ mutants with altered colicin or VmpA protein levels and in ColV+ strains with repressed transfer properties.     

Transduction of the chemotactic cAMP signal across the plasma membrane ofDictyostelium cells

AggregatingDictyostelium cells secrete cAMP during cell aggregation. cAMP induces two fast responses, the production of more cAMP (relay) and directed cell locomotion (chemotaxis). Extracellular cAMP binds to G-protein-coupled receptors leading to the activation of second messenger pathways, including the activation of adenylyl cyclase, guanylyl cyclase, phospholipase C and the opening of plasma membrane Ca²⁺ channels. Many genes encoding these sensory transduction proteins have been cloned and null mutants of nearly all components have been characterized in detail. Undoubtedly, activation of adenylyl cyclase is the most complex, involving G-proteins, a soluble protein called CRAC and components of the MAP kinase pathway. Null mutants in this pathway do not aggregate, but can exhibit chemotaxis and develop normally when supplied with exogenous cAMP. The pathways leading to the activation of phospholipase C were identified, but unexpectedly, deletion of the phospholipase C gene has no effect on chemotaxis and development, nor on intracellular Ins(1,4,5)P₃ levels; the metabolism of this second messenger will be discussed in some detail. Activation of guanylyl cyclase is G-protein-dependent and essential for chemotaxis. Analysis of a collection of chemotactic mutants reveals that most mutants are defective in either the production or intracellular detection of cGMP, thereby placing this second messenger at the center of chemotactic signal transduction. Analysis of the cAMP-mediated opening of plasma membrane calcium channels in signal transduction mutants suggests that it has two components, one that depends on G-proteins and intracellular cGMP and one that is G-protein-independent.     

Calcium binding, structural stability and guanylate cyclase activation in GCAP1 variants associated with human cone dystrophy

Guanylate cyclase activating protein 1 (GCAP1) is a neuronal Ca²⁺ sensor (NCS) that regulates the activation of rod outer segment guanylate cyclases (ROS-GCs) in photoreceptors. In this study, we investigated the Ca²⁺-induced effects on the conformation and the thermal stability of four GCAP1 variants associated with hereditary human cone dystrophies. Ca²⁺ binding stabilized the conformation of all the GCAP1 variants independent of myristoylation. The myristoylated wild-type GCAP1 was found to have the highest Ca²⁺ affinity and thermal stability, whereas all the mutants showed decreased Ca²⁺ affinity and significantly lower thermal stability in both apo and Ca²⁺-loaded forms. No apparent cooperativity of Ca²⁺ binding was detected for any variant. Finally, the nonmyristoylated mutants were still capable of activating ROS-GC1, but the measured cyclase activity was shifted toward high, nonphysiological Ca²⁺ concentrations. Thus, we conclude that distorted Ca²⁺-sensor properties could lead to cone dysfunction.     

Comparative study of the effect of thymosin and supernatant from epithelial thymic cells on antibody production (author's transl)]

A thymic extract (TE) was prepared from supernatant of mice thymic epithelial cultures according to the purification of thymosin. TE and thymosin stimulated, in vitro, the immune response of mouse against deep red blood cells.     

Die Carbohydrasen der SpinnmilbeTetranychus urticae Koch (Acari,Tromb{ie307-1}diformes,Tetranychidae)diformes,Tetranychidae)

Summary In preparations of crushed whole spider mites (Tetranychus urticae Koch), the enzymes capable of hydrolyzing carbohydrates were identified. The products of the enzymic hydrolysis were detected by paper chromatography. The following substrates were hydrolyzed: Starch, maltose, sucrose, trehalose, melibiose, lactose, melezitose and raffinose. Not attacked were: Cellobiose, cellulose, pectin and pectic acid. In the homogenates there must be present an amylase, an -glucosidase, a -h-fructosidase, an - and -galactosidase. There is no indication for the presence of a -glucosidase, a cellulase, a pectinase and polygalacturonase.     

Symbiotic efficiency in spontaneous mutants of Rhizobium legumino-sarum resistant to streptomyocin, spectinomycin, or kanamycin]

Symbiotic effectiveness of 45 mutant strains selected from four wild effective strains of Rhizobium leguminosarum for resistance to streptomycin, spectinomycin or kanamycin was determined on Vicia faba. Loss of effectiveness occurred in twenty of these mutants; distribution of ineffective mutants was uniform among the three types of antibiotic resistant mutants but varied with the parent strain from which mutants have been derived.     

Larval necrophagy and photopigment phenocopying inMusca domestica (L.)

Summary The intensity of photopigment modification in green-eyed house flies increased with increasing larval density and the relative frequency of +-type larvae. Phenocopying in these precursor deficient mutants resulted from the consumption of their dead 3rd instar +-type sibs.Supported by C.U.N.Y., Faculty Research Award Program Grant 1103 and N.I.H. Biomedical Research Support Program 5-SO5-RR07064.We thank Alice Chabora and B. Wallace for their discussions and Sandra Smolin for her technical assistance. I.C. McDonald of the USDA Metabolism and Radiation Research Laboratory, Fargo, N.D., kindly supplied marker strains of house fly eye color mutants.     

基于热电制冷的液冷源系统设计

本文介绍了一种热电制冷的液冷源系统组成及其设计过程,阐述了应用热电制冷在小功率液冷源系统的设计思路。其控制精度高、可靠性高、体积小、重量轻等优点,使其具有一定的实用价值和推广意义。     

Changes in the activities of protein kinase modulators in the cerebellum of mice due to ethanol,caffeine, or phenobarbital administration

Summary Decreased activities of both the inhibitory modulator of adenosine 35-monophosphate (cAMP)-dependent protein kinase (A-PK) as well as the stimulatory modulator of guanosine 35-monophosphate (cGMP)-dependent protein kinase (G-PK) from the mouse cerebellum were noted due to the administration of excessive doses of ethanol, caffeine, and phenobarbital for up to 28 days. The dose-dependence of the inhibition of A-PK or the stimulation of G-PK was observed as a function of the amount of protein kinase modulators in the cerebellum of mice receiving different doses of ethanol.Acknowledgments. This work was supported by a grant (RR 08119-06-PK modulator project) from NIH, USA. J.L. Williams, T. Floyd-Jones, C.F. Duggans, D.L. Boone, and S.O. Smith were prebaccalaureate trainees of MBS program. Authors thank Dr J.F. Kuo of Emory University for encouragement in this project.     

On the genesis of the soil mantle of the region of Manaus,Central Amazonia,Brazil

Summary The dynamics of the forest to the north of Manaus is tightly linked to that of the soil. The latosol that covers the plateau, which supports a dense forest, consists from top to bottom of: (a) a brown, clayey organic horizon (0.3 m), (b) a yellow horizon, very rich in clay but permeable (from 0.3 to 4 m), (c) a nodular horizon rich in Al and Fe oxides (from 4 to 9 m), and (d) a horizon which still preserves the sedimentary structures of the parent sandstone, where quartz is intensely dissolved and kaolinite crystallizes in pores. In perfectly flat areas, the clay of the organic horizon is destroyed by acidocomplexolysis, and the dissolved Al is transported vertically by the drainage water. A part of this Al is used to make the gibbsite nodules of horizon (c), and the rest is used to make kaolinite in horizon (d). Because aluminum is thus conserved within any vertical prism, the rate of destruction of horizon (a) is equivalent to the rate of advance of the kaolinization zone into the sediment: the latosol is said to be in equilibrium, the surface remains perfectly flat as it slowly sinks, the quantity of kaolinite increases with time, and the silica released by quartz dissolution in the whole profile is exported by drainage water to the water table. In contrast, near drainage axes, however small initially, the drainage becomes inclined toward the axis. Part of the Al released by acidocomplexolysis of horizon (a) is now exported to rivers, and Al is no longer conserved within any given prism. The rate of advance of the kaolinization zone (d) into the sediment now becomes less than the rate of destruction of horizon (a) and the surface sinks faster than that of the surrounding plateau. After this differential podzolization has gone on long enough, it creates a network of geochemical valleys characterized by convex slopes and bounded by sandy soils (campinas). The vegetation becomes sparser and sparser. At the end, only some bushes and lichens survive on the white sand.Acknowledgments. The authors are indebted to Dr E. Merino (Dept. of Geology, Indiana University) for helpful criticisms and suggestions. This research was carried out in I.N.P.A. (Instituto Nacional de Pesquisas da Amazonia) and was financially supported by the CNPq-CNRS/ORSTOM conv.     

Sr2+ can become incorporated into an agonist-sensitive,cytoplasmic Ca2+ store in a cell line derived from the equine sweat gland epithelium

We have explored the properties of a Ca²⁺-dependent cell-signalling pathway that becomes active when cultured equine sweat gland cells are stimulated with ATP. The ATP-regulated, Ca²⁺-influx pathway allowed Sr²⁺ to enter the cytoplasm but permitted only a minimal influx of Ba²⁺. Experiments in which cells were repeatedly stimulated with ATP suggested that Sr²⁺, but not Ba²⁺, could become incorporated into the agonist-sensitive, cytoplasmic Ca²⁺ store. Further evidence for this was provided by experiments using ionomycin, a Ca²⁺ ionophore which has no affinity for Sr²⁺.     

Deciduogenic effects of mediators of the polyphosphatidylinositol pathway in pseudopregnant mice

Intraluminal injections (15 l) of either concanavalin A (125 g) or ionophore A 23187 (0.01 mol) induced a decidual cell reaction (DCR) in the uterus of day 4.5 pseudopregnant mice. However, when these agents were administered in different combinations with each other or with CaCl₂ (15 mol) and phorbol-12-myristate-13-acetate (1.6 nmol), interacting effects occurred to either enhance or inhibit each of the others' independent deciduogenic capacities. The results suggest that the polyphosphatidylinositol pathway and Ca²⁺ are involved in the induction of the DCR in mice with complex interactions occurring between the active components of the pathway to modulate the outcome of the transformation process.     

Partial pancreatectomy in rats causes an impairment of the glucose-induced stimulation of pancreatic islet blood flow

Summary Adult rats were subjected to either a sham operation (S-rats) or a 60% partial pancreatectomy (P-rats). Both P- and S-rats were normoglycemic and normoinsulinemic after surgery. Four weeks later, the animals were injected i.v. with 1 ml of either 0.9% (w/v) saline or 30% (w/v) D-glucose, and after 5 min whole pancreatic blood flow (PBF) and islet blood flow (IBF) were measured, using a microsphere technique. In the saline-injected P-rats both PBF and IBF values were, higher than in S-rats (p<0.001 for both values). Administration of glucose had no effects on PBF in either S- or P-rats when compared to saline-injected animals. IBF was, however, markedly increased (p<0.01) by glucose in S-rats in comparison with saline-injected S-rats, whilst no difference in IBF was observed between glucose- and saline-injected P-rats. The fraction of PBF diverted through the islets (fIBF) was approximately 10% in S-rats and 20% in P-rats. Glucose increased fIBF in S-rats, but had no effect in P-rats. In conclusion, in S-rats a glucose-stimulated insulin release is accompanied by an increase in IBF, but this is not observed in P-rats.     

Etude comparative de l'effet de la thymosine et d'un extrait de cultures cellulaires épithéliales thymiques sur la production d'anticorps

Summary A thymic extract (TE) was preparated from supernatant of mice thymic epithelial cultures according to the purification of thymosin. TE and thymosin stimulated, in vitro, the immune response of mouse against sheep red blood cells.

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Les auteurs remercient Mademoiselle Condemine Florence pour son aide technique durant ce travail.     

Partial pancreatectomy in rats causes an impairment of the glucose-induced stimulation of pancreatic islet blood flow

Adult rats were subjected to either a sham operation (S-rats) or a 60% partial pancreatectomy (P-rats). Both P- and S-rats were normoglycemic and normoinsulinemic after surgery. Four weeks later, the animals were injected i.v. with 1 ml of either 0.9% (w/v) saline or 30% (w/v) D-glucose, and after 5 min whole pancreatic blood flow (PBF) and islet blood flow (IBF) were measured, using a microsphere technique. In the saline-injected P-rats both PBF and IBF values were higher than in S-rats (p less than 0.001 for both values). Administration of glucose had no effects on PBF in either S- or P-rats when compared to saline-injected animals. IBF was, however, markedly increased (p less than 0.01) by glucose in S-rats in comparison with saline-injected S-rats, whilst no difference in IBF was observed between glucose- and saline-injected P-rats. The fraction of PBF diverted through the islets (fIBF) was approximately 10% in S-rats and 20% in P-rats. Glucose increased fIBF in S-rats, but had no effect in P-rats. In conclusion, in S-rats a glucose-stimulated insulin release is accompanied by an increase in IBF, but this is not observed in P-rats.     

Sexual dimorphism in the defensive secretion of a carabid beetle

Summary The defensive secretions of male and femaleOodes americanus display striking qualitative differences. Altogether 13 carboxylic acids were identified in the secretions of the two sexes. Methacrylic, crotonic, and tiglic acids are produced exclusively by the female; the male lacks these unsaturated components, but produces their saturated analogs. 2-Methylbutyric acid is a major component produced by both sexes. Shared components also include hexanoic, (E)-2-hexenoic, benzoic, and (E)-2-octenoic acid, of which the latter two had not previously been reported from carabid beetles.Paper no. 98 in the series Defense Mechanisms of Arthropods; no. 97 is by Smedley et al., J. Lepid. Soc., in press.     

Homeostatic and innate immune responses: role of the transmembrane glycoprotein CD98

The transmembrane glycoprotein CD98 is a potential regulator of multiple functions, including integrin signaling and amino acid transport. Abnormal expression or function of CD98 and disruption of the interactions between CD98 and its binding partners result in defects in cell homeostasis and immune responses. Indeed, expression of CD98 has been correlated with diseases such as inflammation and tumor metastasis. Modulation of CD98 expression and/or function therefore represents a promising therapeutic strategy for the treatment and prevention of such pathologies. Herein, we review the role of CD98 with focus on its functional importance in homeostasis and immune responses, which could help to better understand the pathogenesis of CD98-associated diseases.