Naturally acquired CD8+ cytotoxic T lymphocytes against the Plasmodium falciparum circumsporozoite protein.

In rodent malaria model systems, protective immunity induced by immunization with irradiated sporozoites is eliminated by in vivo depletion of CD8+ T cells, and adoptive transfer of CTL clones against the circumsporozoite protein protects against malaria. We recently demonstrated that volunteers immunized with irradiated Plasmodium falciparum sporozoites produce CTL against peptide 368-390 of the P. falciparum circumsporozoite protein. To determine whether natural exposure to malaria induced similar CTL, we studied 11 adult, male, life-long residents of a highly malarious area of Kenya, who were selected because their lymphocytes had been shown to proliferate after stimulation with peptides 361-380, 371-390, or 368-390 and because nine had been resistant to malaria in previous studies. In four of the 11 individuals there was peptide-specific, genetically restricted, CTL activity. In all four individuals, this activity was unaffected by depletion of CD4+ T cells. In three volunteers the activity was eliminated or reduced by depletion of CD8+ T cells; in the fourth volunteer the CD8+ T cell depletion was uninterpretable. This first demonstration of CD8+ T cell, genetically restricted, Ag-specific CTL against a malaria protein among individuals exposed to endemic malaria provides a foundation for studying the relationship between circulating CTL and resistance to malaria infection.     

Potato Virus X—a New Report from Turnip (Brassica rapa L.) in India

A virus isolated from turnip in Aligarh, India, which caused mild mosaic, mottling and curling of leaves followed by overall stunting of plants, was characterized as potato virus X (PVX) on the basis of its host range, biological and physical properties, particle morphology, ultrastructural studies, and serological relationship.     

Effect of acetazolamide on cerebral blood flow and capillary patency.

This study investigated the effects 2 h after administration of acetazolamide on cerebral blood flow and the pattern of cerebral capillary perfusion. Arterial blood pressure, heart rate, arterial blood gases, and pH were recorded in two groups of rats along with either regional cerebral blood flow or the percentage of capillary volume per cubic millimeter and number per square millimeter perfused as determined in cortical, thalamic, pontine, and medullary regions of the brain. Blood pressure, heart rate, and arterial PCO2 were not significantly different between the rats receiving acetazolamide (100 mg/kg) and the controls. Arterial blood pH was significantly lower in the acetazolamide rats. Blood flow increased significantly in the cortical (+ 102%), thalamic (+ 89%), and pontine (+ 88%) regions receiving acetazolamide. In control rats, approximately 60% of the capillaries were perfused in all of the examined regions. The percentage of capillaries per square millimeter perfused was significantly greater in the cortical (+ 52%), thalamic (+ 49%), and pontine (+ 47%) regions of acetazolamide rats compared with controls. In the medulla the increases in blood flow and percentage of capillaries perfused were not significant. Thus in the regions that acetazolamide increased cerebral blood flow, it also increased the percentage of capillaries perfused.     

Calcium activated proteolysis of fibrous proteins in central nervous system

A Ca²⁺ activated protease(s) capable of hydrolyzing several polypeptides at neutral pH including cytoskeletal proteins, actin, myosin, tubulin and neurofilament triplet was identified in calf brain cortex. The enzyme activity precipitates at 75 mM KCl, pH 6.5 – 7.0 and is inhibited by the sulfhydryl inhibitors, N-ethylmaleimide and para-chloromercuribenzoate and the protease inhibitors, antipain, pepstatin and leupeptin, leupeptin being the most effective.     

Prostaglandins do not modulate the positive chronotropic and inotropic effects of sympathetic nerve stimulation and injected norepinephrine in the isolated blood perfused canine atrium

In isolated canine atrium, perfused with blood from a donor dog, the infusions of both prostaglandins (PG)I₂ and E₂ (0.1–1 μg/min) into the sinus node arterial cannula neither altered the sinus rate and developed tension nor the positive chronotropic and inotropic responses elicited by either electrical stimulation or by injected norepinephrine. Infusion of arachidonic acid (10–100 μg/min), a precursor of PGs, or indomethacin (15–20 μg/min), an inhibitor of PG synthesis, into the sinus node arterial cannula also failed to alter the increase in sinus rate or developed tension produced by either adrenergic stimulus in the isolated atria. When arachidonic acid, 100–300 μg/kg or PGI₂, 1 μg/kg, were injected into the jugular vein of the donor dog, they produced a fall in systemic blood pressure; this effect of arachidonic acid but not of PGI₂ was abolished by indomethacin, 1 mg/kg. During administration of either arachidonic acid or indomethacin to the donor dog, the positive chronotripic and inotropic responses to adrenergic stimuli in the isolated atria also remained unaltered. These data indicate that PGs do not modulate adrenergic transmission in the blood perfused canine atrium.     

Peptidohydrolases of Soybean Root Nodules : IDENTIFICATION, SEPARATION, AND PARTIAL CHARACTERIZATION OF ENZYMES FROM BACTEROID-FREE EXTRACTS

Nodule extracts prepared from Glycine max var Woodworth possessed endopeptidase, aminopeptidase, and carboxypeptidase activities. Three distinct endopeptidase activities could be resolved by disc-gel electrophoresis at pH 8.8. According to their order of increasing electrophoretic mobility, the first of these enzymes hydrolyzed azocasein and n-benzoyl-l-Leu-beta-naphthylamide, while the second hydrolyzed n-benzoyl-l-Arg-beta-naphthylamine (Bz-l-Arg-betaNA), n-benzoyl-l-Arg-p-nitroanilide (Bz-l-Arg-pNA), and azocasein. The third endopeptidase hydrolyzed Bz-l-Arg-betaNA, Bz-l-Arg-pNA, and hemoglobin. Fractions of these enzymes extracted from electrophoresis gels were shown to have pH optima from 7.5 to 9.8. All of the endopeptidases were completely inhibited by diisopropylphosphorofluoridate, demonstrating that they were serine proteases.Aminopeptidase activity was measured using amino acyl-beta-naphthylamides. Electrophoresis of nodule extracts at pH 6.8 resolved the aminopeptidase activity of nodule extracts into at least four fractions based on mobility and on activities toward amino acyl-beta-naphthylamides. The major activity of two of the aminopeptidases was directed toward l-Leu- and l-Met-beta-naphthylamide, while the other two aminopeptidases exhibited broader specificity and were capable of hydrolyzing a large number of amino acyl-beta-naphthylamides. Two of the aminopeptidases extracted from electrophoresis gels were classified as thiol type enzymes, and all four aminopeptidases had neutral to basic pH optima.     

Sodium chloride resistant cell line from haploidDatura innoxia mill

Summary A cell line resistant to sodium chloride was selected from callus cultures of haploidDatura innoxia by cloning under selective pressure. Cells of the resistant cell line retained their resistance even after subculture in absence of NaCl. Plantlets could be regenerated from resistant cells in the presence as well as absence of NaCl. In contrast, regeneration of plantlets was not possible from normal cells in the presence of NaCl, although regeneration readily occurred in the absence of NaCl.To examine the stability of the resistance in the long-term, callus cultures were initiated in presence of NaCl from stem expiants of the differentiated plantlets. All expiants of plantlets derived from resistant cells showed callus formation. This callus, derived from resistant explants, retained the trait of resistance upon subculture.     

Transfer of genes to Chinese hamster ovary cells by DNA-mediated transformation

We have transferred DNa to Chinese hamster ovary (CHO) cells by DNA-mediated transformation. CHO tk- cells were transformed with the clones gene for herpes simplex virus thymidine kinase (HSV-tk) and were found to have a 50-fold lower frequency of transformation than mouse Ltk- cells at the same DNA dosage. By altering the amount of tk gene and carrier DNA present, frequencies of up to 5 x 10(-5) were obtained. CHO HSV-tk+ transformants were very stable, and in several clones the HSV-tk gene copies integrated in higher-molecular-weight DNA. These cells also exhibited cotransformation for unselected markers. CHO lines were also transformed at a frequency of 10(-4) with the bacterial gene Ecogpt in a SV40-pBR322 vector. CHO tk-cells could be transformed at a frequency of 10(-7) with cellular DNA isolated from CHO tk+ cells. CHO cells offer a well-defined genetic system within which to transfer either cloned or whole cellular DNAs.     

Batch and multistage continuous ethanol fermentation of cellulose hydrolysate and optimum design of fermentor by graphical analysis

Batch and single-flow four-stage continuous ethanol fermentations of bagasse hydrolysate have been investigated at pH 4.0 and 30°C with a strain of the yeast Saccharomyces cerevisiae. The studies were carried out in the laboratory four-stage cascade continuous stirred-tank fermentors at varying feed glucose concentrations (10, 14, 18, and 22%). The range of dilution rates employed varied from 0.05 to 0.2 hr^?1. The hydrolysate was supplemented with a cheap nitrogen source (CNS), CaCl₂·H₂O and MgSO₄·7H₂O. A 2% (v/v) CNS concentration was found to be sufficient to avoid growth limitation at a glucose concentration of 116 g/liter. The conditions of continuous culture in a multistage system are predicted by a graphical method based on batch-culture data. The results thus obtained are compared with those predicted by kinetic models and with the experimental results. The variations between the results obtained experimentally and those computed either by a kinetic model or by graphical analyses were found to be within the limits of experimental error. The solutions based on the concept of minimum residence time necessary to achieve the desired biomass or product concentrations are also discussed.     

Increased production of cellulase of Trichoderma sp. by pH cycling and temperature profiling

Cultivation of Trichoderma reesei QM 9414 on 3% (w/v) cellulose medium (C/N ratio = 8.5) produced 4.5 IU/ml celulase 180 hr at a cell growth of 8.0 g/liter (0.266 g cell/g cellulose). It corresponded to an average cellulase productivity 25.0 IU/liter/hr (3.5 IU/g cell/hr). In the same medium 9.5 g/liter cell mass (0.316 g cell/g cellulose), 6.2 IU/ml cellulase, and 38.75 IU/liter/hr (4.0 IU/g cell/hr) cellulase productivity could be obtained using pH cycling condition during cultivation. Cell mass, cellulase yield, and productivity were further increased to 10.0 g/liter, 7.2 IU/ml, and 44.0 IU/liter/hr (4.5 IU/g cell/hr), respectively, by simultaneous pH cycling and temperature profiling strategy. Results are described.