Infectivity,viability and effects of Paranosema locustae (Microsporidia) on juveniles of Dichroplus maculipennis (Orthoptera: Acrididae: Melanoplinae) under laboratory conditions

Infectivity and effects on host of a long-term stored aqueous suspension of Paranosema locustae on juveniles of Dichroplus maculipennis, a pest grasshopper in parts of the Pampas and Patagonia, were evaluated. Infections developed in 90–97.8% of treated individuals. Mortality increased with time, reaching highest values at 30–40 days post-inoculation (79.5–100%). Infected nymphs showed significantly slower development.     

Transformation of Nicotiana tabacum,N. debneyi,and N. rustica: Inheritance and protoplast expression of antibiotic resistance

Agrobacterium tumefaciens strains harbouring plasmid vectors pBCAT1, pVU1011 or pMON806 were used to transform leaf explants of Nicotiana tabacum cultivars Delgold and Candel, N. debneyi, and N. rustica var. NRT. Transgenic plants resistant to the selective agents kanamycin, hygromycin or methotrexate were regenerated and used as sources of leaf mesophyll protoplasts. Protoplasts divided and regenerated plants in the presence of selective agents at levels inhibitory to protoplasts of non-transformed plants. Cross-resistance of protoplasts to more than one selective agent was not observed in this study which suggests that this approach may lead to an efficient interspecific somatic hybrid selection system.     

Deactivation of the Photosystem II oxidation (S) states by 2-(3-chloro-4-trifluoromethyl)anilino-3,5-dinitrothiophene (ANT2p) and the putative role of carotenoid

Addition of 2-(3-chloro-4-trifluoromethyl)anilino-3,5-dinitrothiophene (ANT2p) to detergent-solubilised Photosystem II (PS II) particles results in the photo-oxidation of carotenoid and inhibition of the steady-state oxygen-evolution rate. It has been proposed that ANT2p may modify the water-splitting reactions by mediating the transfer of reducing equivalents from endogenous electron donors, such as carotenoid, to the S₂ and S₃ oxidation states of PS II. In this paper we present evidence indicating that ANT2p can interact with PS II at two separate loci. The water-splitting complex is shown to be the primary site of attack by ANT2p, since artificial electron donors, such as 1,5-diphenylcarbazide (DPC), can restore PS II photochemical activity by feeding reducing equivalents directly to the reaction centre. The ANT2p interaction at this site is light-intensity dependent. A second inhibitory site close to the reaction centre P-680 chlorophyll is detected at slightly higher ANT2p concentrations. The inhibition at this site is unaffected either by changes in the actinic light intensity or by the addition of electron donors. The flash-induced oxidation of carotenoid has an ANT2p concentration dependence and an insensitivity to DPC which suggests that it results from the inhibition of the reaction centre and not with that of the water-splitting complex.     

Effects of piretanide on plasma fibrinolytic activity,platelet aggregation and platelet factor-4 release in man

Piretanide, 4-phenoxy-3-(pyrrolidinyl)-5-sulphamoyl benzoic acid, apart from being an efficient diuretic, enhances endogenous plasma fibrinolytic activity after a single dose of 6 mg administered by oral route. After ingestion of the drug, acceleration of fibrinolytic acitivity became manifest within 1 h, reached its peak in 3 h and was associated with a fall in fibrinogen and diminished urokinase excretion. Piretanide did not cause lysis of fibrinin vitro. Primary platelet aggregation, induced by adenosine-diphosphate, was inhibited by piretanide. Inin vitro experiments piretanide led to effective inhibition of adenosine-diphosphate-induced platelet aggregation with complete inhibition at 5 mM concentration. Piretanide led to a highly significant decrease of platelet factor-4 release.     

Effect of Gossypol on Trypomastigotes and Amastigotes of Trypanosoma cruzi

Bloodstream Trypanosoma cruzi trypomastigotes isolated from infected mice undergo reduction of motility and structural damages after 5 to 45 min exposure to gossypol at concentrations ranging from 5 to 50 μM. When 1% serum albumin is added to the incubation medium, no alterations of parasites are observed, even with 100 μM gossypol. Intracellular T. cruzi amastigotes in infected Vero cell cultures exposed to 5 μM gossypol for 2 h do not show changes. Incubation with 5 μM gossypol for 48 h produces complete disruption of host cells; however, the amastigotes they contain show only mineor alterations. The observations indicate that, in protein-rich media, gossypol is complexed into associations which have no activity on the different forms of the T. cruzi biological cycle.     

Redox conditions for stimulation of in vitro folding and assembly of the glycoprotein hormone chorionic gonadotropin

The formation of native disulfide bonds during in vitro protein folding can be limiting in obtaining biologically active proteins. Thus, optimization of redox conditions can be critical in maximizing the yield of renatured, recombinant proteins. We have employed a folding model, that of the beta subunit of human chorionic gonadotropin (hCG- beta), to investigate in vitro oxidation conditions that facilitate the folding of this protein, and have compared the in vitro rates obtained with the rate of folding that has been observed in intact cells. Two steps in the folding pathway of hCG-beta were investigated: the rate-limiting events in the folding of this protein, and the assembly of hCG-beta with, hCG-alpha. The rates of these folding events were determined with and without protein disulfide isomerase (PDI) using two different types of redox reagents: cysteamine and its oxidized equivalent, cystamine, and reduced and oxidized glutathione. Rates of the rate-limiting folding events were twofold faster in cysteamine/cystamine redox buffers than in glutathione buffers in the absence of PDI. Optimal conditions for hCG-beta folding were attained in a 2 mM glutathione buffer, pH 7.4, that contained 1 mg/mL PDI and in 10muM cysteamine/cystamine, pH 8.7, without PDI. Under these conditions, the half-time of the ratelimiting folding event was 16 to 20 min and approached the rate observed in intact cells (4 to 5 min). Moreover, folding of the beta subunit under these conditions yields a functional protein, based on its ability to assemble with the alpha subunit. The rates of assembly of hCG-beta with hCG-alpha in the cysteamine/cystamine or glutathione/PDI redox buffers were comparable (t(1/2/sb> = 9 to 12 min)). These studies show that rates of folding and assembly events that involve disulfide bond formation can be optimized by a simple buffer system composed of cysteamine and cystamine. (c) 1994 John Wiley & Sons, Inc.     

Role of Liv-52 in protection against beryllium intoxication

An ayurvedic medicine, Liv-52, was studied as a prophylactic agent against beryllium-induced toxicity in rats. Administration of berylliumper se caused severe degenerative and necrotic changes in kidneys, liver, and uterus. Beryllium exposure also reduced glycogen content, activities of alkaline phosphatase, succinate-dehydrogenase, and adenosine-triphosphatase in these organs. On the contrary, activities of acid phosphatase and glucose-6-phosphatase showed marginal increase. Liv-52-primed rats exhibited comparatively less marked toxic effects.     

Influence of endotoxin on the stereoselective pharmacokinetics of oxprenolol,propranolol, and verapamil in the rat

The influence of endotoxin-induced inflammation on the enantioselective pharmacokinetics of propranolol, oxprenolol, and verapamil, which bind to α₁-acid glycoprotein, was studied in the rat. The racemic mixtures were given orally. In the control animals, for propranolol and oxprenolol, the plasma concentrations of the (R)-enantiomer were higher than those of the (S)-enantiomer, while for verapamil the reverse was true. Protein binding and intrinsic clearance are the main factors responsible for this enantioselectivity. After endotoxin treatment, for the three drugs tested the plasma concentrations and the plasma binding of both enantiomers were significantly increased. This effect was more pronounced for (R)-propranolol, (R)-oxprenolol, and (S)-verapamil than for their respective antipodes. The enantioselective effect of endotoxin on the plasma concentrations of the drugs studied seems mainly due to the enantioselective increase in binding to α₁-acid glycoprotein. © 1994 Wiley-Liss, Inc.     

Interactions between size and temperature influence fecundity and longevity of a tortricid moth,Zeiraphera canadensis

Females of Zeiraphera canadensis Mut. & Free., the spruce bud moth, were reared in the laboratory at constant and alternating temperatures, and in an outdoor insectary, to (1) determine the effects of temperature, age and size on several reproductive parameters and, (2) to test the hypothesis that body size-temperature interactions influence longevity and realized fecundity. Egg maturation was linearly related to age and large moths developed eggs at a higher rate than small ones. Mcan lifetime oviposition rate reached a maximum and remained stable at temperatures 20° C while the mean lifetime rate of egg maturation increased linearly with temperature, indicating that higher temperatures adversely affect oviposition. The production of nonviable eggs increased with age but also with temperature, suggesting high temperature (25° C) reduces egg quality and/or hinders fertilization. The realized fecundity and longevity of females reared under an alternating temperature regime (mean 20° C) was significantly less than that of females reared at constant 20° C. Similar realized fecundity, longevity and mean lifetime oviposition rates for females reared at temperatures alternating between 10 and 25° C (mean 20° C) and those at constant 25° C reflected the inability of females to recover from elevated diurnal temperatures. Longevity was positively related to female body size at constant 15 and 20° C but the relationships were negative for moths exposed to diurnal temperatures equal to or exceeding 25° C. Due to the reduced longevity of large moths at high temperatures, linear regressions between size and realized fecundity were only significant at constant temperatures 20° C. At higher temperatures, the size-fecundity relationship became curvilinear as a result of the diminished reproductive output of large individuals. Reduced fecundity and longevity of large females at high temperatures may have been due to elevated internal temperatures of large-bodied moths. Large females in a controlled-environment chamber maintained at 25° C developed an internal temperature excess (i.e. temperature above ambient) of nearly 2° C while small-bodied females exceeded ambient by only 0.3° C. However, when held at 20° C, the temperature excess of large-bodied moths was much less than 1° C and small-bodied females did not differ from ambient. Such interactions between temperature and body size suggest that there should be stabilizing selection toward moderate-sized individuals and may explain the absence of size-related effects on fecundity and longevity previously reported for several other lepidopterans.     

Piper longum Constituents Induce PANC-1 Human Pancreatic Cancer Cell Death under Nutrition Starvation

Pancreatic cancer is a highly aggressive form of cancer with a poor prognosis, partly due to ‘austerity’, a phenomenon of tolerance to nutrient deprivation and survival in its hypovascular tumor microenvironment. Anti-austerity agents which preferentially diminish the survival of cancer cells under nutrition starvation is regarded as new generation anti-cancer agents. This study investigated the potential of Piper longum constituents as anti-austerity agents. The ethanolic extract of Piper longum was found to have preferential cytotoxicity towards PANC-1 human pancreatic cancer cells in a nutrient-deprived medium (NDM). Further investigation led to the identification of pipernonaline ( 3 ) as the lead compound with the strongest anti-austerity activity, inducing cell death and inhibiting migration in a normal nutrient medium, as well as strongly inhibiting the Akt/mTOR/autophagy pathway. Therefore, pipernonaline ( 3 ) holds promise as a novel antiausterity agent for the treatment of pancreatic cancer.