A Paecilomyces fumosoroseus mutant over-producing chitinase displays enhanced virulence against Bemisia tabaci

A Paecilomyces fumosoroseus strain was mutagenized by u.v. Among 200 colonies, one mutant (M84), showed a large and stable chitin hydrolysis-halo. Glucose consumption and biomass production were similar for M84 and the parental strain. Chitinase was inducible by chitin and repressed by glucose in both strains but, when they were grown on minimal medium plus colloidal chitin as sole carbon source, the parental and M84 strains yielded 198 and 690 mol N-acetylglucosamine, respectively. This results indicate that the mutant strain synthesized a chitinase with a higher activity. Bioassays against Bemisia tabaci nymph, showed that M84 incited a 2-fold higher incidence of disease compared to the parental strain.     

Effectiveness of a reserve network for the conservation of the endemic marsupial Micoureus travassosi in Atlantic Forest remnants in southeastern Brazil

Habitat loss and fragmentation are serious threats to biodiversity conservation in the Atlantic Forest. A network of protected reserves is essential to the protection of native fauna and flora. However, internal and external factors may threaten the preservation of biota, thus population viability analyses (PVA) are important tools in reserve design and management planning. A PVA was carried out, using the computer package VORTEX, to assess the effectiveness of the reserve network of Rio de Janeiro State in Brazil in retaining viable populations of the endemic marsupial Micoureus travassosi. The PVA takes into account demographic, genetic and environmental stochastic events and catastrophes (fire). Rio de Janeiro state has 31 reserves, and 20 of those were considered to retain viable populations for 100 years, whereas eight were predicted to suffer from genetic decay, two from both genetic decay and demographic stochasticity, and one of them probably has an extinct population. The minimum area of suitable habitat needed to maintain a minimum viable population of M. travassosi is estimated at 3600ha. Sensitivity analysis was run for mortality, sex ratio, percentage of reproductive females, inbreeding depression and probability of catastrophes, and suggests that inbreeding depression is important in small population sizes, whereas the effects of catastrophes were significant only for large populations. Although the model indicates that some populations will suffer from demographic and/or genetic stochasticity, the reserve network of Rio de Janeiro state will likely keep M. travassosi's populations for the next 100 years.     

Characterization of the First VanB Vancomycin-Resistant <Emphasis Type="Italic">Enterococcus faecium</Emphasis> Isolated in a Spanish Hospital

We report the detection and characterization of the first vancomycin-resistant VanB-type Enterococcus faecium to be isolated in a Spanish hospital. Sequence analysis of the vanB gene showed that this isolate belonged to subtype vanB2. Moreover, PCR amplification analysis indicated that the vanB gene cluster was linked to a Tn5382-like transposon.     

The Oligopeptide Permease (Opp) of the Plant Pathogen <Emphasis Type="Italic">Xanthomonas axonopodis</Emphasis> pv. <Emphasis Type="Italic">citri</Emphasis>

The oligopeptide permease (Opp), a protein-dependent ABC transporter, has been found in the genome of Xanthomonas axonopodis pv. citri (Xac), but not in Xanthomonas campestris pv. campestris (Xcc). Sequence analysis indicated that 4 opp genes (oppA, oppB, oppC, oppD/F), located in a 33.8-kbp DNA fragment present only in the Xac genome, are arranged in an operon-like structure and share highest sequence similarities with Streptomyces roseofulvus orthologs. Nonetheless, analyses of the GC content, codon usage, and transposon positioning suggested that the Xac opp operon does not have an exogenous origin. The presence of a stop codon at one of the ATP-binding domains of OppD/F would render the uptake system nonfunctional, but detection of a single polycistronic mRNA and periplasmic OppA in actively growing bacteria suggests that the Opp permease is active and could contribute to the distinct nutritional requirements and host specificities of the two Xanthomonas species.     

Preoptic alpha 1- and alpha 2-noradrenergic agonists induce, respectively, PGE2-independent and PGE2-dependent hyperthermic responses in guinea pigs

We have shown previously that norepinephrine (NE) microdialyzed into the preoptic area (POA) of conscious guinea pigs stimulates local PGE(2) release. To identify the cyclooxygenase (COX) isozyme that catalyzes the production of this PGE(2) and the adrenoceptor (AR) subtype that mediates this effect, we microdialyzed for 6 h NE, cirazoline (alpha(1)-AR agonist), and clonidine (alpha(2)-AR agonist) into the POA of conscious guinea pigs pretreated intrapreoptically (intra-POA) with SC-560 (COX-1 inhibitor) or nimesulide or MK-0663 (COX-2 inhibitors) and measured the animals' core temperature (T(c)) and intra-POA PGE(2) responses. Cirazoline induced T(c) rises promptly after the onset of its dialysis without altering PGE(2) levels. NE and clonidine caused early falls followed by late rises of T(c); intra-POA PGE(2) levels were closely correlated with this thermal course. COX-1 inhibition attenuated the clonidine-induced T(c) and PGE(2) falls but not the NE-elicited hyperthermia, but COX-2 inhibition suppressed both the clonidine- and NE-induced T(c) and PGE(2) rises. Coinfused cirazoline and clonidine reproduced the late T(c) rise of clonidine but not its early fall and also not the early rise produced by cirazoline; on the other hand, the PGE(2) responses were similar to those to NE. Prazosin (alpha(1)-AR antagonist) and yohimbine (alpha(2)-AR antagonist) blocked the effects of their respective agonists. These results indicate that alpha(1)- and alpha(2)-AR agonists microdialyzed into the POA of conscious guinea pigs evoke distinct T(c) responses: alpha(1)-AR activation produces quick, PGE(2)-independent T(c) rises, and alpha(2)-AR stimulation causes an early T(c) fall and a late, COX-2/PGE(2)-dependent T(c) rise.     

Tumor-induced endothelial cell activation: role of vascular endothelial growth factor

Proangiogenic, proliferative effects of tumors have been extensively characterized in subconfluent endothelial cells (EC), but results in confluent, contact-inhibited EC are critically lacking. The present study examined the effect of tumor-conditioned medium (CM) of the malignant osteoblastic cell line MG63 on monolayer, quiescent bovine aorta EC. MG63-CM and MG63-CM + CoCl₂ significantly increased EC survival in serum-starved conditions, without inducing EC proliferation. Furthermore, MG63-CM and MG63-CM + CoCl₂, both containing high amounts of vascular endothelial growth factor (VEGF), induced relevant phenotypic changes in EC (all P < 0.01) involving increase of nucleoli/chromatin condensations, nucleus-to-cytosol ratio, capillary-like vacuolated structures, vessel-like acellular areas, migration through Matrigel, growth advantage in reseeding, and factor VIII content. All these actions were significantly inhibited by VEGF and VEGF receptor (VEGFR2) blockade. Of particular importance, a set of similar effects were detected in a human microvascular endothelial cell line (HMEC). With regard to gene expression, incubation with MG63-CM abolished endogenous VEGF mRNA and protein but induced a clear-cut increase in VEGFR2 mRNA expression in EC. In terms of mechanism, MG63-CM activates protein kinase B (PKB)/Akt, p44/p42-mitogen-activated protein kinase (MAPK)-mediated pathways, as suggested by both inhibition and phosphorylation experiments. In conclusion, tumor cells activate confluent, quiescent EC, promoting survival, phenotypic, and gene expression changes. Of importance, VEGF antagonism converts MG63-CM from protective to EC-damaging effects. vascular endothelial growth factor receptor 2; MG63-conditioned medium     

Dimethyl Sulfoxide and Ebselen Prevent Convulsions Induced by 5-Aminolevulinic Acid

We investigated whether intrastriatal (i.s.) administration of 5-aminolevulinic acid (ALA) induces oxidative damage and whether behavioral alterations induced by i.s. administration of ALA could be affected by antioxidants. Unilateral injection of ALA (6 micromol/striatum) increased (approximately 30%) thiobarbituric acid-reactive substances (TBARS), but did not affect striatal content of total thiol groups. ALA-induced body asymmetry was not prevented by pretreatment with ascorbic acid (100 mg/kg, s.c.), dimethyl sulfoxide (DMSO, 0.5 microl/striatum, i.s.) or ebselen (10 nmol/striatum, i.s.). ALA-induced convulsions were not prevented by ascorbic acid, but were partially prevented by DMSO and completely prevented by ebselen. Ebselen completely prevented the increase of striatal TBARS induced by ALA. Results obtained suggest the involvement of reactive species in ALA-induced convulsions and may be of value in understanding the physiopathology of neurological dysfunctions associated to ALA overload.     

Impact of the training program on lipid profile and cardiac health

The aim of this study was to investigate the effects of training programs on serum lipid profile and myocardial oxidative stress. Male Wistar rats (2 mo-old) were divided into three groups (n = 8): sedentary (S), loadless trained (T) and trained-overload 2% body weight (TL). T and TL were trained through swimming for 9 weeks. T and TL rats had increased myocardial lipoperoxide (TBA) and lipid hydroperoxide (HP), whereas HP was higher in TL than in T animals. Superoxide dismutase (SOD) activities were lowest in TL. Myocardial glutathione peroxidase (GSH-Px) was lower in TL than in T and S rats. TL decreased HDL-cholesterol and increased LDL-cholesterol. The serum lactate dehydrogenase and TBA were increased, while SOD and GSH-Px activities were decreased in TL rats. Loadless training was able to improve HDL-cholesterol and to reduce LDL-cholesterol. In conclusion, the loadless training program induced beneficial effects on lipid profile, while overload training induced dyslipidemic profile that was associated with serum oxidative stress. The overload training program was deleterious relative to loadless training program, increasing myocardial oxidative stress.     

Resource pulses,species interactions,and diversity maintenance in arid and semi-arid environments

Arid environments are characterized by limited and variable rainfall that supplies resources in pulses. Resource pulsing is a special form of environmental variation, and the general theory of coexistence in variable environments suggests specific mechanisms by which rainfall variability might contribute to the maintenance of high species diversity in arid ecosystems. In this review, we discuss physiological, morphological, and life-history traits that facilitate plant survival and growth in strongly water-limited variable environments, outlining how species differences in these traits may promote diversity. Our analysis emphasizes that the variability of pulsed environments does not reduce the importance of species interactions in structuring communities, but instead provides axes of ecological differentiation between species that facilitate their coexistence. Pulses of rainfall also influence higher trophic levels and entire food webs. Better understanding of how rainfall affects the diversity, species composition, and dynamics of arid environments can contribute to solving environmental problems stemming from land use and global climate change.