Ornamentation of achene silica walls and its contribution to the systematics of <Emphasis Type="Italic">Eleocharis</Emphasis> (Cyperaceae)

Micromorphology of the achene surface of 26 Brazilian species of Eleocharis was studied by scanning electron microscopy in order to evaluate its usefulness in the taxonomy of the genus. The results point out two patterns of cell organization according to silica structures of achenes. The first corresponds to a group of species (group A) that have small to medium cells arranged vertically. The second is found in those species (group B) with medium to large cells arranged horizontally. These data were useful in separating species of Eleocharis subgenus Scirpidium and E. subgenus Limnochloa (group B) from E. subgenus Eleocharis (group A). However, group A shows considerable variation in silica wall arrangement. Eleocharis squamigera, previously considered as part of E. subgenus Eleocharis, shows features rather similar to those of Scirpidium, confirming recent phylogenies. The subgenus Limnochloa was clearly distinguished from others by achenes with large cells (over 55 μm width), presence of crenate or repand anticlinal walls, and some orifices near the wall in some species. The silica wall ornamentation seems to be a useful morphological tool for studying relationships between subgenera and distinguishes Limnochloa from the other subgenera.     

Fungal Diversity Associated to the Olive Moth, Prays Oleae Bernard: A Survey for Potential Entomopathogenic Fungi

Olive production is one of the main agricultural activities in Portugal. In the region of Trás-os-Montes, this crop has been considerably affected by Prays oleae. In order to evaluate the diversity of fungi on Prays oleae population of Trás-os-Montes olive orchards, larvae and pupae of the three annual generations (phyllophagous, antophagous and carpophagous) were collected and evaluated for fungal growth on their surface. From the 3,828 larvae and pupae, a high percentage of individuals exhibited growth of a fungal agent (40.6%), particularly those from the phyllophagous generation. From all the moth generations, a total of 43 species from 24 genera were identified, but the diversity and abundance of fungal species differed between the three generations. Higher diversity was found in the carpophagous generation, followed by the antophagous and phyllophagous generations. The presence of fungi displaying entomopathogenic features was highest in the phyllophagous larvae and pupae, with Beauveria bassiana as the most abundant taxa. The first report of Beauveria bassiana presence on Prays oleae could open new strategies for the biocontrol of this major pest in olive groves since the use of an already adapted species increases the guarantee of success of a biocontrol approach. The identification of antagonistic fungi able to control agents that cause major olive diseases, such as Verticillium dahliae, will benefit future biological control approaches for limiting this increasingly spreading pathogen.     

Effect of insecticide resistance on development, longevity and reproduction of field or laboratory selected Aedes aegypti populations

Aedes aegypti dispersion is the major reason for the increase in dengue transmission in South America. In Brazil, control of this mosquito strongly relies on the use of pyrethroids and organophosphates against adults and larvae, respectively. In consequence, many Ae. aegypti field populations are resistant to these compounds. Resistance has a significant adaptive value in the presence of insecticide treatment. However some selected mechanisms can influence important biological processes, leading to a high fitness cost in the absence of insecticide pressure. We investigated the dynamics of insecticide resistance and its potential fitness cost in five field populations and in a lineage selected for deltamethrin resistance in the laboratory, for nine generations. For all populations the life-trait parameters investigated were larval development, sex ratio, adult longevity, relative amount of ingested blood, rate of ovipositing females, size of egglaying and eggs viability. In the five natural populations, the effects on the life-trait parameters were discrete but directly proportional to resistance level. In addition, several viability parameters were strongly affected in the laboratory selected population compared to its unselected control. Our results suggest that mechanisms selected for organophosphate and pyrethroid resistance caused the accumulation of alleles with negative effects on different life-traits and corroborate the hypothesis that insecticide resistance is associated with a high fitness cost.     

Morphological,biochemical, physiological and molecular aspects of the response of Fusobacterium nucleatum exposed to subinhibitory concentrations of antimicrobials

Subinhibitory concentrations (SICs) of antimicrobials may result in alterations in bacterial biology with implications for its potential aggression. This has considerable importance for the resident microbiota. Our aim was to analyze the effects of SICs of antimicrobials on the morphological, biochemical, physiological and molecular characteristics of the resident anaerobic Fusobacterium nucleatum. Fourteen strains were obtained from F. nucleatum ATCC 25586, selected by culturing on SICs of ampicillin, ampicillin/sulbactam, clindamycin, chloramphenicol, levofloxacin, metronidazole and piperacillin/tazobactam and subsequent culturing in the absence of drugs. Antimicrobial susceptibility, bacterial morphology, biochemical profiles and biofilm formation were evaluated. Genotyping and analysis of protein profiles were also performed. The antimicrobial susceptibility patterns showed that most of the derived strains were less sensitive to the antimicrobials, even after culturing them without drugs. Morphological and cell complexity alterations were observed, mainly in strains grown in SICs of β-lactam; these strains also expressed a reduced ability for biofilm formation. The other strains showed an increase in biofilm formation but no apparent morphological changes. Alterations were observed in the carbohydrate metabolism patterns and in the activity of microbial enzymes. Several proteins were positively or negatively regulated and there was polymorphism in the DNA from all derived strains. Therefore, SICs of antimicrobials induce alterations in F. nucleatum, which directly impact its biology. These results emphasize the risk of inadequate antibioticotherapy, which may have serious implications for clinical microbiology and infectious diseases and also may interfere with the host–bacteria relationship.     

Polyploidization as a retraction force in plant genome evolution: sequence rearrangements in triticale

Background

Polyploidization is a major evolutionary process in plants where hybridization and chromosome doubling induce enormous genomic stress and can generate genetic and epigenetic modifications. However, proper evaluation of DNA sequence restructuring events and the precise characterization of sequences involved are still sparse.

Methodology/Principal Findings

Inter Retrotransposons Amplified Polymorphism (IRAP), Retrotransposons Microsatellite Amplified Polymorphism (REMAP) and Inter Simple Sequence Repeat (ISSR) largely confirmed the absence of any intraspecific variation in wheat, rye and triticale. The comparative analysis of banding profiles between wheat and rye inbred lines revealed 34% of monomorphic (common to both parental species) bands for the ten different primer combinations used. The analysis of triticale plants uncovered nearly 51% of rearranged bands in the polyploid, being the majority of these modifications, due to the loss of rye bands (83%). Sequence analysis of rye fragments absent in triticale revealed for instance homology with hydroxyproline-rich glycoproteins (HRGP), a protein that belongs to a major family of inducible defence response proteins. Conversely, a wheat-specific band absent in triticale comprises a nested structure of copia-like retrotransposons elements, namely Claudia and Barbara. Sequencing of a polyploid-specific band (absent in both parents) revealed a microsatellite related sequence. Cytological studies using Fluorescent In Situ Hybridization (FISH) with REMAP products revealed a widespread distribution of retrotransposon and/or microsatellite flanking sequences on rye chromosomes, with a preferential accumulation in heterochromatic sub-telomeric domains.

Conclusions/Significance

Here, we used PCR-based molecular marker techniques involving retrotransposons and microsatellites to uncover polyploidization induced genetic restructuring in triticale. Sequence analysis of rearranged genomic fragments either from rye or wheat origin showed these to be retrotransposon-related as well as coding sequences. Further FISH analysis revealed possible chromosome hotspots for sequence rearrangements. The role of chromatin condensation on the origin of genomic rearrangements mediated by polyploidization in triticale is also discussed.     

Immunoprophylaxis of respiratory syncytial virus: global experience

In sarcoidosis, host genetic factors are discussed as contributing to disease susceptibility and course. Since tumor necrosis factor (TNF)-α is a central mediator of granuloma formation and since elevated TNF-α levels are found during active phases of sarcoidosis, genetic polymorphisms correlating with influences on TNF-α levels are of special interest. The complete sequencing of the MHC region and the increase in the number of identified gene polymorphisms in this locus associated with TNF-α production offer the opportunity of detecting new genes associated with sarcoidosis and perhaps of defining disease-associated haplotypes that bear the potential of serving as predictive markers for this disease.     

Expression of the selectable marker gene bsrm in BALB/MK cells induces apoptosis by overproduction of hydrogen peroxide.

Transduction of the retroviral vector LBmSN, which expresses the blasticidin S resistance gene bsrm in the murine keratinocyte cell line BALB/MK, induces death in these cells. Cell death is caused by a factor called DOKEB (death factor obtained from keratinocytes expressing bsrm), which is released before the cells' death. In this report we describe and discuss the purification and characterization of DOKEB. Our results were as follows. (i) The 5-day-old medium from the modified BALB/MK cells with LBmSN was used for purification and characterization by filtration and chromatography: DOKEB was a stable and highly hydrophilic compound, with a molecular mass less than that of 1 amino acid. (ii) The conditioned medium containing DOKEB was reactive against thiobarbituric acid and dichlorofluorescein diacetate. (iii) DOKEB activity was neutralized by the incubation of the conditioned medium with catalase. Therefore, our conclusion is that the BALB/MK cells expressing bsrm produce a large amount of hydrogen peroxide, which catalyzes the process of apoptosis of those cells.