Physiognomic-structural characterization of dry- and humid-forest fragments (Atlantic Coastal Forest) in Pernambuco State,NE Brazil

Although both dry- and humid-forests have been intensively studied, their physiognomic and structural differences have not yet been well characterized. The present work seeks to identify the physiognomic and structural differences between fragments of humid- and dry-forests in the state of Pernambuco, Brazil. The humid-forest fragment was located in the municipality of São Vicente Férrer (7°37′ S × 35°28′ W) and the dry-forest fragment in the municipality of Aliança (7°38′ S × 35°14′ W). Fifty 10 × 20 m plots were delimited in each area and all individual living plants with a diameter at breast height (DBH) ≥5 cm were included. It was observed that the total density (1,390 ind ha^?1) and total basal area (29.9 m² ha^?1) were greater in the humid-forest than the dry-forest (649 ind ha^?1 and 18.7 m² ha^?1, respectively). Individual plants in the humid-forest tended to be taller, while those in the dry-forest had generally larger diameters. There were also differences in the most structurally important families as, for example, Clusiaceae, Moraceae, Myristicaceae, and Sapotaceae in the humid-forest and Sterculiaceae, Fabaceae, Bignoniaceae, and Moraceae in the dry-forest. Physiognomic differences were also observed in the different forest layers, as the group of species composing the canopy of the dry-forest are dominated by deciduous species, while many of the species in the understory are evergreen. In the humid-forest, both the understory and canopy are predominantly composed of evergreen species. The examination of the phytosociological parameters of average height and species richness allowed us to identify physiognomic differences between humid and dry forests in Pernambuco State. The present study demonstrated that dry forests are not simply floristic/structural subsets of humid forests, and that there is a great need to establish conservation areas to protect these important but spatially restricted forests within the Atlantic coastal domain.     

Post-translational enzyme modification by the phosphopantetheinyl transferase is required for lysine and penicillin biosynthesis but not for roquefortine or fatty acid formation in Penicillium chrysogenum

NRPSs (non-ribosomal peptide synthetases) and PKSs (polyketide synthases) require post-translational phosphopantetheinylation to become active. This reaction is catalysed by a PPTase (4'-phosphopantetheinyl transferase). The ppt gene of Penicillium chrysogenum, encoding a protein that shares 50% similarity with the stand-alone large PPTases, has been cloned. This gene is present as a single copy in the genome of the wild-type and high-penicillin-producing strains (containing multiple copies of the penicillin gene cluster). Amplification of the ppt gene produced increases in isopenicillin N and benzylpenicillin biosynthesis. A PPTase-defective mutant (Wis54-PPT(-)) was obtained. It required lysine and lacked pigment and penicillin production, but it still synthesized normal levels of roquefortine. The biosynthesis of roquefortine does not appear to involve PPTase-mediated modification of the synthesizing enzymes. The PPT(-) mutant did not require fatty acids, which indicates that activation of the fatty acid synthase is performed by a different PPTase. Complementation of Wis54-PPT(-) with the ppt gene restored lysine biosynthesis, pigmentation and penicillin production, which demonstrates the wide range of processes controlled by this gene.     

Overweight,Waist Circumference,Age, Gender,and Insulin Resistance as Risk Factors for Hyperleptinemia

Objective: To evaluate the influence of overweight, waist circumference, age, gender, and insulin resistance as risk factors for hyperleptinemia. Research Methods and Procedures: A cross‐sectional study was carried out in a population of 197 subjects: 59 men (21 aged <60 years and 38 aged ≥60 years) and 138 women (37 aged <60 years and 101 aged ≥60 years). The groups were stratified by overweight and normal weight. After a 12‐hour fasting period, we measured serum leptin and insulin levels with radioimmunoassay methods. We also measured serum glucose and lipid profile. The data were analyzed by means of comparative tests. A variance‐stabilizing transformation (natural logarithmic) was used to meet multiple linear regression, analysis of covariance, and logistic regression models. Results: The leptin serum levels were higher and statistically significant in young and older women than they were in men. We observed an interaction between gender and body mass index to explain the difference in leptin levels (p < 0.0001). Our study demonstrated an inverse relationship between leptin with age and high‐density lipoprotein cholesterol. In logistic regression analysis, the overweight × gender interaction and waist circumference have a statistically significant influence as independent variables on hyperleptinemia (overweight × gender odds ratio = 6.81; 95% confidence interval, 1.10 to 46.86; p < 0.05 and waist circumference odds ratio = 4.34; 95% confidence interval, 1.47 to 12.83; p = 0.001). Discussion: Women who were overweight or had a higher waist circumference (women ≥ 88 cm and men ≥ 102 cm) have a significantly higher risk of having hyperleptinemia. The increase in age as an isolated variable is not a risk factor for hyperleptinemia.     

Release and effect ofγ-Aminobutyric acid (GABA) on rat pineal melatonin productionin vitro

1. 3H-gamma-Aminobutyric acid (GABA) release elicited by a depolarizing K+ stimulus or by noradrenergic transmitter was examined in rat pineals in vitro. 2. The release of 3H-GABA was detectable at a 20 mM K+ concentration in medium and increased steadily up to 80 mM K+. 3. In a Ca2+-free medium 3H-GABA release elicited by 30 mM K+, but not that elicited by 50 mM K+, became blunted. 4. Norepinephrine (NE; 10(-6)-10(-4) M) stimulated 3H-GABA release from rat pineal explants in a dose-dependent manner. 5. The activity of 10(-5) M NE on pineal GABA release was suppressed by equimolecular amounts of prazosin or phentolamine (alpha 1- and alpha 1/alpha 2-adrenoceptor blockers, respectively) and was unaffected by propranolol (beta-adrenoceptor blocker). 6. The alpha 1-adrenoceptor agonist phenylephrine (10(-7)-10(-5) M) and the beta-adrenoceptor agonist isoproterenol (10(-5) M) mimicked the GABA releasing activity of NE, while 10(-7) M isoproterenol failed to affect it; the alpha 2-adrenoceptor agonist clonidine (10(-7)-10(-5) M) did not modify 3H-GABA release. 7. The addition of 10(-4) M GABA or of the GABA transaminase inhibitor gamma-acetylenic GABA or aminooxyacetic acid inhibited the melatonin content and/or release to the medium in rat pineal organotypic cultures. 8. GABA at concentrations of 10(-5) M or greater partially inhibited the NE-induced increase in melatonin production by pineal explants. 9. The depressant effect of GABA on melatonin production was inhibited by the GABA type A receptor antagonist bicuculline; bicuculline alone increased the pineal melatonin content. Baclofen, a GABA type B receptor agonist, did not affect the pineal melatonin content or release. 10. The decrease in serotonin (5-HT) content of rat pineal explants brought about by NE was not modified by GABA; GABA by itself increased 5-HT levels. 11. These results indicate that (a) GABA is released from rat pineals by a depolarizing stimulus of K+ through a mechanism which is partially Ca2+ dependent; (b) NE releases rat pineal GABA via interaction with alpha 1-adrenoceptors; (c) GABA inhibits melatonin production in vitro via interaction with GABA type A receptor sites; and (d) GABA's effect on NE-induced melatonin release does not correlate with the lack of effect on the NE-induced decrease in pineal 5-HT content.     

Post-Translational Tubulin Modifications in Human Astrocyte Cultures

The cytoskeletal protein tubulin plays an integral role in the functional specialization of many cell types. In the central nervous system, post-translational modifications and the expression of specific tubulin isotypes in neurons have been analyzed in greater detail than in their astrocytic counterparts. In this study, we characterized post-translational specifications of tubulin in human astrocytes using the normal human astrocyte (NHA; Lonza) commercial cell line of fetal origin. Immunocytochemical techniques were implemented in conjunction with confocal microscopy to image class III β-tubulin (βIII-tubulin), acetylated tubulin, and polyglutamylated tubulin using fluorescent antibody probes. Fluorescent probe intensity differences and colocalization were quantitatively assessed with the ‘EBImage’ package for the statistical programming language R. Colocalization analysis revealed that, although both acetylated tubulin and polyglutamylated tubulin showed a high degree of correlation with βIII-tubulin, the correlation with acetylated tubulin was stronger. Quantification and statistical analysis of fluorescence intensity demonstrated that the fluorescence probe intensity ratio for acetylated tubulin/βIII-tubulin was greater than the ratio for polyglutamylated tubulin/βIII-tubulin. The open source GEODATA set GSE819950, comprising RNA sequencing data for the NHA cell line, was mined for the expression of enzymes responsible for tubulin modifications. Our analysis uncovered greater expression at the mRNA level for enzymes reported to function in acetylation and deacetylation as compared to enzymes implicated in glutamylation and deglutamylation. Taken together, the results represent a step toward unraveling the tubulin isotypic expression profile and post-translational modification patterns in astrocytes during human brain development.     

Genetic diversity in a world germplasm collection of tall fescue

Festuca arundinacea Schreb., commonly known as tall fescue, is a major forage crop in temperate regions. Recently, a molecular analysis of different accessions of a world germplasm collection of tall fescue has demonstrated that it contains different species from the genus Festuca and allowed their rapid classification into the three major morphotypes (Continental, Mediterranean and Rhizomatous). In this study, we explored the genetic diversity of 161 accessions of Festuca species from 29 countries, including 28 accessions of INTA (Argentina), by analyzing 15 polymorphic SSR markers by capillary electrophoresis. These molecular markers allowed us to detect a total of 214 alleles. The number of alleles per locus varied between 5 and 24, and the values of polymorphic information content ranged from 0.627 to 0.840. In addition, the accessions analyzed by flow cytometry showed different ploidy levels (diploid, tetraploid, hexaploid and octaploid), placing in evidence that the world germplasm collection consisted of multiple species, as previously suggested. Interestingly, almost all accessions of INTA germplasm collection were true hexaploid tall fescue, belonging to two eco-geographic races (Continental and Mediterranean). Finally, the data presented revealed an ample genetic diversity of tall fescue showing the importance of preserving the INTA collection for future breeding programs.     

RGD-containing peptides and cyclic AMP have antagonistic roles in the morphology of Mucor rouxii

Summary. The tripeptide Arg-Gly-Asp (RGD) (1 mM) as well as the polymer ProNectin F (20 nM) added to culture medium of the fungus Mucor rouxii (defined medium) produced a delay in the switch from isodiametric growth to tip growth; at the time of germination the mother cell had a 4.6 times larger volume with 3.6 times more germ tubes per cell than control germinating sporangiospores. Disruption of the actin network with 2 µg of cytochalasin A per ml blocked the switch to tip growth; the effect was analogous to the one of 150 µM dibutyryl–cyclic AMP (cAMP), which we previously described to promote isodiametric growth via protein kinase A. 150 µM dibutyryl-cAMP antagonises partially the effect of 1 mM RGD; the cells still emit several germ tubes per mother cell but their number is smaller and the volume of the cell at germ tube emission is larger than with RGD alone. At higher concentrations the dibutyryl-cAMP overrides completely the effect of RGD. Our results suggest that M. rouxii has an RGD recognition system and demonstrate that RGD-containing peptides have a profound effect on the isotropic stage of growth and on the establishment of cell polarity and that cAMP analogues can override this effect.Correspondence and reprints: Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Pabell'n 2, Ciudad Universitaria, Universidad de Buenos Aires, 1428 Buenos Aires, ArgentinaReceived January 29, 2003; accepted March 10, 2003; published online September 23, 2003     

Seroprevalence of Hepatitis B virus infection among an Afro-descendant community in Brazil

Furnas dos Dionísios is an Afro-Brazilian black community whose descendants were mainly fugitive slaves that established themselves in the State of Mato Grosso do Sul (MS), Brazil. The population is comprised mainly of low socioeconomic individuals who are engaged in agricultural activities. The objective of this study was to investigate the prevalence of hepatitis B (HB) and its correlation with epidemiological data obtained from the community. The studied population totaled 260 individuals with ages varying from 1 to 79 years (median 20). One hundred thirty-three (51.2%) were females and 127 (48.8%) were males. A high prevalence for anti-HBc was observed (42.7%), with present infection detected in 9.2% of the subjects who were also HB surface antigens (HBs Ag) positive; 27.3% were anti-HBc and anti-HBs reactive, and 6.2% had anti-HBc as only marker. The prevalence for anti-HBc was proportional to age, reaching its highest peak in age categories greater than 50. No serological marker was detected in children under the age of 2 years, however anti-HBc was present in 12 subjects with ages between 2 and 14 years, of these 8 (7.4%) were HBsAg positive. Among individuals over the age of 15 years, 99 were anti-HBc reactive, of these 16 (10.5%) were also HBsAg positive, thus suggesting an increased prevalence of HBV carriers among children and adolescents. The risk factors observed in this community that were significantly associated with anti-HBc positivity were age (over 20 years) and having an anti-HBc positive mother. Both HBeAg and anti-HBe were detected in 44.4% of the samples tested. HBsAg subtypes found in the studied population were adw2 (77.7%) and ayw2 (23.3%). While intrafamilial transmission was most likely responsible for HBV infection among children, other routes such as sexual contact might be considered for individuals with ages over 15 years.     

Are 90K/MAC-2BP serum levels correlated with poor prognosis in HCC patients? Preliminary results

In this study we assessed the prognostic significance of 90K/MAC-2BP serum levels in a group of 40 hepatocellular carcinoma patients. This glycoprotein is a new, interesting serum marker that reflects the immune reaction of the host against certain viral infections and tumors such as breast, ovarian and pancreatic cancer. Hepatocellular carcinoma (HCC) is one of the most widespread tumors in the world. AFP is currently the most useful marker for HCC, in spite of its poor diagnostic sensitivity. In this study 40 cirrhotic HCC patients were enrolled. The prevalence of viral hepatic infections in this group was 73% for HCV, 8% for HBV, and 8% for both viruses. Thirteen percent of the patients showed non-virus-related liver damage. 90K serum levels were assayed by an ELISA kit and AFP levels by a chemiluminescent enzyme immunometric system. The overall survival curves were estimated by the Kaplan-Meier method, taking into account age, sex, 90K and AFP serum levels. Statistical analysis showed a highly significant influence on overall survival of age below 70 years and 90K serum levels below the cutoff of 14 ng/mL. Serum AFP (< or = 20 ng/mL) had positive prognostic value only when it was associated with 90K levels (p < 0.02, log-rank).     

Short-term regulation of excitation-contraction coupling by the beta1a subunit in adult mouse skeletal muscle

The beta1a subunit of the skeletal muscle voltage-gated Ca2+ channel plays a fundamental role in the targeting of the channel to the tubular system as well as in channel function. To determine whether this cytosolic auxiliary subunit is also a regulatory protein of Ca2+ release from the sarcoplasmic reticulum in vivo, we pressure-injected the beta1a subunit into intact adult mouse muscle fibers and recorded, with Fluo-3 AM, the intracellular Ca2+ signal induced by the action potential. We found that the beta1a subunit significantly increased, within minutes, the amplitude of Ca2+ release without major changes in its time course. beta1a subunits with the carboxy-terminus region deleted did not show an effect on Ca2+ release. The possibility that potentiation of Ca2+ release is due to a direct interaction between the beta1a subunit and the ryanodine receptor was ruled out by bilayer experiments of RyR1 single-channel currents and also by Ca2+ flux experiments. Our data suggest that the beta1a subunit is capable of regulating E-C coupling in the short term and that the integrity of the carboxy-terminus region is essential for its modulatory effect.