The structure of the 5' domain of yeast 18S rRNA has been probed by dimethyl sulfate (DMS), either in "native" deproteinized molecules or in the 4OS ribosomal subunits. DMS-reacted RNA has been used ...as a template for reverse transcription and a large number of reactive sites, corresponding to all types of bases have been mapped by a primer extension procedure, taking advantage of blocks in cDNA elongation inmediately upstream from bases methylated at atom position involved in the base-pair recognition of the template. Since the same atom positions are protected from DMS in base-paired nucleotides, the secondary structure status of each nucleotide can be directly assessed in this procedure, thus allowing to evaluate the potential contribution of proteins in modulating subunit rRNA conformation.
Anticardiolipin antibodies (ACL) are associated with the presence of several clinical conditions. To determine the clinical interest of their evaluation, we reviewed all the results of ACL ...determinations performed in our laboratory during 1990 and 1991. 266 analyses (232 patients) were carried out. Determinations of IgG and IgM type ACL were performed by ELISA. ACL values were positive or slightly positive in 40% of the analyzed samples. Diagnosis was mentioned as the grounds for 212 requests (186 patients). ACL were positive (> m + 3SD) in about 40% of patients with autoimmune disease or with at least two of the following pathologies: autoimmune disease, venous or arterial thromboembolism, recurrent abortion.
Response of Cucumis sativus L. seedlings to Pb exposure Gonçalves, Jamile F.(Universidade Federal do Rio Grande do Sul Centro de Ciências da Saúde Departamento de Fisiologia e Farmacologia,Universidade Federal de Santa Maria Centro de Ciências Naturais e Exatas Departamento de Química); Becker, Alexssandro G.(Universidade Federal de Santa Maria Centro de Ciências da Saúde Departamento de Fisiologia e Farmacologia); Pereira, Luciane B.(Universidade Federal de Santa Maria Centro de Ciências Naturais e Exatas Departamento de Química) ...
Brazilian Journal of Plant Physiology,
2009, Letnik:
21, Številka:
3
Journal Article
In this study, the effects of lead (Pb) on growth, photosynthetic pigments concentration, lipid peroxidation, electrolyte leakage percentage (ELP), protein oxidation, aminolevulinate dehydratase ...(ALA-D; E.C. 4.2.1.24), ascorbate peroxidase (APX; E.C. 1.11.1.11), catalase (CAT; E.C. 1.11.1.6) and superoxide dismutase (SOD; E.C. 1.15.1.1) activities, and ascorbic acid (AsA), non-protein thiol groups (NPSH) and total soluble protein concentrations in cucumber seedlings (Cucumis sativus L.) were investigated. Seedlings were grown in vitro in an agar-solidified substrate containing three Pb levels as (C2H3O2)Pb.3H2O (0, 100, 400, and 1000 µmol L-1) for 10 d. Increasing Pb concentrations in substrate enhanced Pb concentration in both roots and shoot. Pb accumulated at a higher amount in roots. Root length and total fresh weight were decreased at the two highest Pb concentrations. Cucumber showed no reduction in shoot length and total dry weight at any Pb level. The highest Pb concentration decreased water content and ALA-D activity as well as increased malondialdehyde, carbonyls and total soluble protein concentrations. Carotenoids concentration enhanced at 100 and 400 µmol Pb L-1, while chlorophyll concentration and ELP were not affected by Pb stress. Activity of APX was inhibited while the activities of CAT and SOD were increased at all Pb concentrations. AsA was enhanced at 400 and 1000 µmol Pb L-1 whereas NPSH were increased only at the highest Pb concentration. Therefore, high Pb-exposure caused oxidative stress, and the antioxidant system of the cucumber seedlings was not sufficient to revert it, contributing for growth reduction.
No presente estudo, os efeitos do chumbo (Pb) sobre o crescimento, a concentração de pigmentos fotossintéticos, a peroxidação lipídica, a percentagem de extravazamento de eletrólitos (ELP), a oxidação protéica, a atividade das enzimas aminolevulinato desidratase (ALA-D; E.C. 4.2.1.24), peroxidase do ascorbato (APX; E.C. 1.11.1.11), catalase (CAT; E.C. 1.11.1.6) e dismutase do superóxido (SOD; E.C. 1.15.1.1) e as concentrações de ácido ascórbico (AsA), de grupos tióis não-protéicos (NPSH) e de proteínas solúveis totais foram investigados em plântulas de pepino (Cucumis sativus L.). As plântulas foram cultivadas in vitro em um substrato solidificado com ágar contendo três concentrações de Pb na forma de (C2H3O2)Pb.3H2O (0, 100, 400 e 1000 µmol L-1), durante 10 dias. O aumento da concentração de Pb no substrato ocasionou um aumento da concentração de Pb tanto nas raízes quanto na parte aérea. O Pb foi acumulado em maior quantidade nas raízes. O comprimento radicular e a matéria fresca total foram diminuídos nas duas maiores concentrações de Pb. O pepino não apresentou redução no comprimento da parte aérea e na matéria seca total nos tratamento de Pb. A maior concentração de Pb diminuiu o conteúdo de água e a atividade da ALA-D bem como aumentou as concentrações de aldeído malônico, de grupos carbonil e de proteínas solúveis totais. A concentração de carotenóides aumentou em 100 e 400 µmol Pb L-1, enquanto a concentração de clorofila e a ELP não foram afetadas pelo estresse com Pb. A atividade da APX foi inibida, enquanto as atividades da CAT e SOD foram aumentadas em todas as concentrações de Pb. A concentração de AsA aumentou sob 400 e 1000 µmol Pb L-1, enquanto a de NPSH aumentou somente na maior concentração de Pb. Portanto, a exposição a altas concentrações de Pb causou estresse oxidativo e o sistema antioxidante das plântulas de pepino não foi capaz de reverter esta situação, contribuindo para a redução no crescimento.
Thirty asymptomatic patients with acute lymphoblastic leukemia who had received prophylactic cranial irradiation (16 pts had 2400 cGy, 14 pts 1800 cGy) and intrathecal methotrexate were studied by ...computed tomography of the brain 60 to 148 months after initiation of prophylaxis. Three of 30 (10%) patients presented abnormal findings: widening of frontal subarachnoid space (1 patient), little area of decreased attenuation coefficient (1 patient), and intracerebral calcifications (1 patient Tomography abnormalities could be detected either in patients treated with 2400 cGy and in those treated with 1800 cGy. None of our patients showed central nervous system dysfunctions on physical examination. The results of our study suggest that tomography findings have a poor clinical significance.
A stepwise physico‐chemical dissection of nucleoli isolated from Chinese hamster ovary cells has allowed the isolation of actively transcribed regions of chromatin, highly enriched in ribosomal ...genes. Nucleolar chromatin could be separated into its various topographical components. This separation should improve our knowledge of the structure/function relationships in chromatin as the fine structure of the nucleolus is very sensitive to changes in ribosomal RNA synthesis.
The spatial distribution of ribosomal genes among the various chromatin areas of the nucleolus was assayed by hybridization with rRNA. In exponentially growing Chinese hamster ovary cells ribosomal genes are predominantly located in the intranucleolar stretches of nucleolus‐associated chromatin. However, ribosomal sequences represent but a very minor part (less than 1 %) of intranucleolar DNA. In an attempt to improve the analysis of the actively transcribed chromatin areas, intranucleolar chromatin was submitted to additional fractionation steps involving, among others, isopycnic separation in metrizamide gradients. In these latter conditions a small subset of intranucleolar chromatin banded with preribosomal ribonucleoprotein. In this subfraction, about one‐third of the DNA sequences corresponded to preribosomal RNA matrix units. The yield of recovery of this intranucleolar chromatin subfraction being closely related to the level of transcriptional activity of ribosomal genes, it appears likely that this separating procedure depends on the presence of ribosomal RNA transcription complexes and could, therefore, represent a general procedure for the isolation of actively transcribed areas from chromatin.
A radio-tracking study on 12 roe deers showed, during spring, displacements, toward lower elevation meadows, of animals living for the rest of the year at upper elevations, in areas almost without ...meadows. In another study, two adult female roe deer, in conditions of controlled grazing from May to September, showed a very low grass consumption and a strong selection both of species and of browsed botanical fractions (flower, leaves, stem). The first study indicated that pasture can be an important resource for roe deer in mountain areas in early spring, while the second one confirms the high feeding selectivity of the species and its preference for browse. The productivity of meadows is much less important than their early offer of new grass in spring, when shrub re-growth is still poor
Uno studio di radio-tracking su 12 caprioli adulti ha evidenziato in primavera sensibili spostamenti, verso prati a bassa quota, degli animali residenti per il resto dell'anno a quote superiori, in zone quasi prive di prati. In un altro studio due capriole adulte in condizioni di pascolo controllato da maggio a settembre hanno mostrato un consumo di erba molto basso e una forte selezione sia delle specie, sia delle frazioni botaniche (fiore, foglie, stelo) brucate. Il primo studio indica che in zone montane il prato e' una risorsa ricercata al momento della ripresa vegetativa primaverile, mentre il secondo conferma la forte selettivita' alimentare della specie e la sua preferenza per il pascolo arbustivo. La produttivita' dei prati appare quindi poco importante rispetto all'offerta precoce di nuova vegetazione, quando la ricrescita arbustiva primaverile e' ancora scarsa
Early steps of ribosomal maturation have been studied by analysis of nucleolar extracts using different extraction procedures. Early 45‐S nucleolar RNA is found to be associated with slowly ...sedimenting elements, distinct from previously described 80‐S and 55‐S nucleolar preribosomes.
This early 45‐S RNA has been shown to be of preribosomal type according to the following criteria. (a) When hybridized with nucleolar DNA, competition with rRNA can be observed; (b) its biosynthesis is sensitive to low doses of actinomycin D; (c) it is methylated at an early stage; (d) it contains no linked poly(A) segments.
This early 45‐S RNA seems to be specifically linked with proteins. The protein content of these early RNA‐protein complexes is significantly lower than that for 80‐S preribosomes. 45‐S RNA sensitivity to nucleolytic activities that can take place in the course of preribosome extraction has been found to be higher in these RNA‐protein complexes than in 80‐S preribosomes.
Identical results were obtained when different mammalian cell species were studied (rat, hamster, or HeLa cells).
More than 100 AFLP markers were utilized for the analysis of genetic variation in 52 genotypes belonging to four goat breeds (Bionda dell'Adamello, Frisa, Orobica, Verzaschese) reared in Lombardy ...Alps. The average estimated heterozigosity at AFLP loci was similar in the four breeds (0.26-0.29).Dice genetic similarity values (GS) across pairs of individuals of the same breed (0.50-0.86) largely overlapped with values for pairs of genotypes of different breeds (0.33-0.82). Analysis of principal coordinates highlighted two groups, one comprising the individuals belonging to Orobica breed, the other comprising those of the other breeds
Piu' di cento marcatori AFLP sono stati utilizzati per studiare la variabilita' genetica presente in 52 genotipi appartenenti a quattro razze di capre (Bionda dell'Adamello, Frisa, Orobica e Verzaschese) allevate sulle Alpi Lombarde. L'eterozigosi media stimata ai loci AFLP e' risultata simile nelle quattro razze (0,26-0,29). I valori di similarita' genetica di Dice (GS) tra coppie di individui appartenenti alla stessa razza (0,50-0,86) sono risultati ampiamente sovrapposti a quelli calcolati tra coppie di genotipi di razze diverse (0,33-0,82). L'analisi delle coordinate principali ha messo in evidenza due gruppi, uno formato da individui di razza Orobica e l'altro da quelli delle altre tre razze
PDF
