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Instituto de Biologia Unicamp






ABSTRACTA IB (2) - 1999


P011-99 Isolation and partial characterization of an extracellular low-molecular mass component with high phenoloxidase activity from Thermoascus aurantiacus

Machuca A, Aoyama H*, Duran N

An extracellular low-molecular mass (530 kDa) component (LMMC) was isolated from liquid cultures containing wheat bran of ascomycete thermophilic Thermoascus aurantiacus. LMMC contained hydroxamic acid moiety and showed very high activity with typical phenoloxidase substrates. At the pH optimum (2.8), the phenoloxidase (PO) activity was quickly lost; a high optimum temperature (80 oC) and an elevated thermostability were observed. The presence of iron in the structure of LMMC may be the responsible for the ability to catalyze oxidation reactions, such as o-dianisidine oxidation. The existence of a hydroxamate-type metal-binding component, most likely hydroxamate siderophore is suggested. Biochemical and Biophysical Research Communications 256: 20-26, 1999 IF= 2.671

P012-99 Glycolytic intermediates as substrates of soybean acid phosphatase isoforms

Ferreira CV, Taga EM, Aoyama H*

Four acid phosphatase isoforms were detected in soybean (Glycine max) seeds, AP1, AP2, AP3A and AP3B. The following apparent Km values were obtained: AP1 (p-nitrophenylphosphate (pNPP): 0.49, phosphoenol pyruvate (PEP): 0.23 mM); AP2 (pNPP: 0.38, PEP: 0.47 mM); AP3A (pNPP: 0.20, PEP: 0.10, glucose-6-P (G6P): 0.30, fructose-6-P (F6P): 0.16 mM) and AP3B (pNPP: 0.086, PEP: 0.078, G6P: 0.31, F6P: 0.33 mM). The enzyme reactions were potently inhibited by molybdate (with pNPP); fluoride (with PEP), and by Cu2+, and p-chloromercuribenzoate (with G6P and F6P). The four acid phosphatase forms are suggested to play important roles in plant metabolism, acting on key glycolytic intermediates. Plant Science 147: 49-54, 1999 IF= 1.274

P013-99 Crystallization and preliminary diffraction data of neurotoxin Ts-gamma from the venom of the scorpion Tityus serrulatus

Golubev AM, Lee WH, Marangoni S, Novello JC*, Oliveira B, Toyama MH, Polikarpov I

Crystals of scorpion neurotoxin Ts-gamma isolated from Tityus serrulatus venom and purified to apparent homogeneity by ion-exchange HPLC were grown using polyethylene glycol 6000 as precipitant and were found to belong to the monoclinic space group P2(1) with cell parameters a = 22.20, b=36.90, c=31.57 Angstrom , beta=100.85 degrees. The crystals diffract beyond 1.73 Angstrom resoltuion at a synchrotrob beamline, being notably stable during X-ray exposure. The structure has been solved by molecular replacement using the very high resolution structure of Sahara scorpion Androctonus australis Hector (PDB code 1 AHO) as a search model. Acta Crystallographica Section D-Biological Crystallography 54: 1440-1441, 1999 IF= 2.118

P014-99 Cytotoxicity of trans-dehydrocrotonin from Croton cajucara on V79 cells and rat hepatocytes

Rodriguez JA, Haun M*

The cytotoxicity of trans-dehydrocrotonin (DHC), an antiulcerogenic diterpene from Croton cajucara, was assessed on a V79 fibroblast cell line and on rat hepatocytes.DNA content, MTT reduction and neutral red uptake (NRU) were evaluated. For the V79 cells IC50 values of 253 and 360 um M were obtained for the NRU and MTT tests. The cytotoxic effect of DHC was time exposure dependent and no ability to recover after treatment was observed. For the rat hepatocytes IC50 values of 8,300 and 400 um M for the MTT, DNA and NRU assays were obtained. The treatment of V79 cells with the conditioned medium resulting after hepatocyte incubation with DHC showed na enhacement of MTT reduction without any evident toxic effects on fibroblasts. These results suggest that DHC has basal cytotoxic effects as observed on V79 fibroblasts and expresses a selective cytotoxicity after is metabolization by the hepatocytes. Planta Medica 65(6): 522-526, 1999 IF= 1.430

P015-99 Survival and molting incidence after heat and cold shocks in Panstrongylus megistus Burmeister

Garcia SL, Rodrigues VLCC, Garcia NL, Ferraz Filho AN, Mello MLS*

Survival and molting incidence were studied after heat and cold shocks in P. megistus with the aim of establishing its response to temperature stress under laboratory rearing conditions and in comparison to T. infestans in order to understand occasional changes in the biological characteristics of specimens captured in nature. The results indicate that no generalization should be made for different reduviid species in terms of the effects of temperature shocks. Memórias do Instituto Oswaldo Cruz 94: 131-137, 1999 IF= 0.440

P016-99 Critical electrolyte concentration of chicken erythrocyte chromatin

Falco JRP, Mello MLS*, Maria SS, Grazziotin NA

This study examined whether chicken erythrocyte chromatin, whose great physicochemical stability is promoted by histone H5, has a critical electrolyte concentration (CEC) value comparable to that of other chromatin types with special condensed paking states but devoid of H5. The affinity for toluidine blue molecules under Mg2+ comparative binding action (CEC) was thus investigated. The CEC value was found to be close to that of heterochromatin from mouse liver cells and to sperm chromatin with histone H1 variants. The phenomenon of programmed cell death was considered to contribute to high CEC values by inducing special states of chromatin condensation. Acta Histochemica et Cytochemica 32: 73-76, 1999 IF= 0.508

P017-99 Critical electrolyte concentration of spermatozoal chromatin containing histone H1 variants

Falco JRP, Mello MLS*

The critical electrolyte concentrations (CEC) of sperm chromatin from species known or suspected to contain histone H1 variants were compared by examining the affinity of their DNA-protein complexes for toluidine blue in presence of Mg2+. Bullfrog, sea urchin, bee and bumblebee spermatozoa were studied. The CEC for Rana catesbeiana and two sea urchin species were similar to that of histone H5-containing chromatin from chicken erythrocytes, thus confirming the biochemical and structural similarities of their DNA-protein complexes. The CEC for bees and the bumblebee, Bombus atratus, showed no particular phylogenetic relationship. We concluded that the CEC of histone H1-containing sperm cell chromatin is a useful indicator of variability in DNA-protein complexes but is of little phylogenetic value. Genetics and Molecular Biology 22: 197-200, 1999 IF= 0.291

P018-99 Morphological dimorphism in the Y chromosome of "pé-duro" cattle in the Brazilian state of Piauí

Britto CMC, Mello MLS*

Y chromosome morphology, outer genital elements and other phenotypic characteristics were examined in 75 "pé-duro" bulls from the Embrapa herd in the Brazilian state of Piauí. The purpose was to investigate possible racial contamination with Zebu animals (Bos taurus indicus) in a cattle that has been considered closest to its European origin (B. t. taurus). The presence of both submetacentric and acrocentric Y chromosomes, typical of B. t. taurus and B. t. indicus, respectively, and the larger preputial sheath in bulls with an acrocentric Y chromosome indicated racial contamination of the "pé-duro" herd with Zebu cattle. Phenotypical parameters involving horn, dewlap, ear, chamfer, and coat color characteristics, indicative of apparent racial contamination, were not associated with acrocentric Y chromosome. Genetics and Molecular Biology 22: 369-393, 1999 IF=0.291

P019-99 Identification of a bisegmented double-stranded RNA virus (Picobirnavirus) in faeces of giant anteaters (Myrmecophaga tridactyla)

Haga IR, Martins SS, Hosomi ST, Vicentini F, Tanaka H, Gatti MSV*

The picobirnavirus (PBV) virions are non-enveloped and have a diameter of 35 nm, with a buoyant density in caesium cloride gradients of 1.38-1.42g/ml. The genome consist of two segments of double-stranded RNA (dsRNA), ranging from 2.2-2.6 to 1.2-1.9 kpb. PBV was identified in epidemiological studies by polyacrylamide gel electrophoresis or by immune electron microscopy in the faeces of human, pigs, rats, chickens and rabbits, with or without diarrhoea. Faecal samples of giant anteater maintained in captivity were collected weekly, during 4 months. The PBV was identified in all samples examined by both above-cited methods. The animals had not clinical signs of diarrhoea or other evidence of enteric disease. A prolonged PBV excretion was also detected in humans with immunosupression. This is the first report of PBV in faeces of a wild animal in captivity, suggesting a wilder range of PBV hosts in nature. The Veterinary Journal 158: 234-236, 1999.
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