Inter‐specific competition and competition‐free space in the tephritid parasitoids Utetes anastrephae and Doryctobracon areolatus (Hymenoptera: Braconidae: Opiinae)

相似文献   

The Straits of Gibraltar: barrier or bridge to Ibero‐Moroccan bat diversity?

Genetic divergence in bat communities was assessed on both sides of the Straits of Gibraltar and cryptic diversity was examined. Screening was carried out using partial sequences of the mitochondrial (mt)DNA cytochrome b gene on 399 individual bats belonging to the 18 species found on both sides of the Straits of Gibraltar. For those bats that showed important genetic discontinuities, molecular markers (ND1 and nuclear RAG2 genes) were added to expand the sampling process. Phylogenetic reconstructions were obtained using maximum parsinomy, genetic distances, maximum likelihood, and Bayesian criteria. As an estimate of bats' flight performance, we measured for each species the wing aspect ratio and wing loading indexes, and correlated them with the maximum pairwise genetic distances obtained between southern Iberian and northern Moroccan populations. Genetic mtDNA distances between populations on both continents exceed 5% in seven out of 18 bat species analysed and unknown lineages were uncovered within the species complexes Myotis nattereri and Myotis mystacinus . We did not find a general pattern in the degree of permeability of the Straits of Gibraltar for bats. Genetic distances were not correlated with the ability to cross the Straits. Our study shows that the cryptic diversity uncovered among bats continues to increase as more regions are studied.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 434–450.     

Removal of silver nanoparticles using live and heat shock Aspergillus niger cultures

Silver nanoparticles (SNPs) are extensively used in many industrial and medical applications; however, the impact of their release in the environment is still considered an understudied field. In the present work, SNPs present in aqueous lab waste water (average size of 30 nm) were used to determine their impact on microflora if released in soil rhizosphere and sewage waste water. The results showed that 24 h incubation with different SNP concentrations resulted in a 2.6-fold decrease for soil rhizosphere microflora and 7.45-fold decrease for sewage waste water microflora, both at 24 ppm. Live and heat shock (50 and 70 °C) Aspergillus niger cultures were used to remove SNP waste, the results show 76.6, 81.74 and 90.8 % SNP removal, respectively after 3 h incubation. There was an increase in the log total bacterial count again after SNP removal by A. niger in the following order: live A. niger < 50 °C heat shock A. niger < 70 °C heat shock A. niger. The pH value decreased from 5.8 to 3.8 in the same order suggesting the production of an acid in the culture media. Scanning electron microscopy images showed agglomeration and/or complexation of SNP particles, in a micron size, in between the fungal mycelia, hence settling on and in between the mycelial network. The results suggest that silver was reduced again and agglomerated and/or chelated together in its oxidized form by an acid in A. niger media. More studies are recommended to determine the acid and the heat shock proteins to confirm the exact mode of action.     

Soil seed bank in different habitats of the Eastern Desert of Egypt

The floristic composition and species diversity of the germinable soil seed bank were studied in three different habitats (desert salinized land, desert wadi, and reclaimed land) in the Eastern Desert of Egypt. Moreover, the degree of similarity between the seed bank and the above-ground vegetation was determined. The seed bank was studied in 40 stands representing the three habitats. Ten soil samples (each 25 × 20 cm and 5 cm depth) were randomly taken per stand. The seed bank was investigated by the seedling emergence method. Some 61 species belonging to 21 families and 54 genera were identified in the germinable seed bank. The recorded species include 43 annuals and 18 perennials. Ordination of stands by Detrended Correspondence Analysis (DCA) indicates that the stands of the three habitats are markedly distinguishable and show a clear pattern of segregation on the ordination planes. This indicates variations in the species composition among habitats. The results also demonstrate significant associations between the floristic composition of the seed bank and edaphic factors such as CaCO₃, electrical conductivity, organic carbon and soil texture. The reclaimed land has the highest values of species richness, Shannon-index of diversity and the density of the germinable seed bank followed by the habitats of desert wadi and desert salinized land. Motyka’s similarity index between the seed bank and the above-ground vegetation is significantly higher in reclaimed land (75.1%) compared to desert wadi (38.4%) and desert salinized land (36.5%).     

The involvement of acetic acid in programmed cell death for the elimination of Bacillus sp. used in bioremediation

A bacterium capable of tolerating some textile effluent conditions such as salinity and high temperature was used to decolorize methyl red (MR). Bacillus sp. isolated from Dead Sea salt was identified by 16S rRNA phylogenetic identification as Bacillus ST (accession number: HQ013327). The bacterium showed 98% color removal under microaerophilic conditions in 24 h at 30 °C and 78% at 80 °C in the presence of mannitol and NaCl. After decolorization an induced programmed cell death (PCD) was proposed to eliminate all living Bacillus ST cells. Acetic acid, which was linked to programmed cell death in yeast, was used in this study to examine its ability to induce PCD in bacteria as well. The acetic acid concentration used was enough to shift the culture pH from alkalinity to neutral. The formation of cytosolic caspase-3 suggested that the programmed cell death occurs through an extrinsic pathway by which mitochondria are by passed and caspases are directly activated. Comet assay which proved death upon the addition of 80 mM acetic acid in 120 min as compared to gamma radiation killed cells. Transmission electron microscopy (TEM) showed cell shrinking, chromatin condensation and membrane blebbing which are all signs of PCD. The mode by which this bacterium follows in programmed cell death is very similar to those in mammalian and yeast cells. The process is proposed to be safe, efficient and cheap for getting rid of cells after bioremediation of colored effluent.     

A NEW PIPINE FROG FROM AN EOCENE CRATER LAKE IN NORTH-CENTRAL TANZANIA

Abstract:  The fossiliferous site of Mahenge, Tanzania, interpreted as a small lake that formed in a kimberlite intrusion, has yielded a vertebrate assemblage that includes scarce frog remains. Radiometric dating of the pipe indicates that the volcanic activity took place at 45·83 ± 0·17 Ma, whereas infilling of the crater was completed in 0·2–1·0 myr after emplacement. The frogs, described herein, are preserved as partially articulated skeletons that represent a new pipine taxon, Singidella latecostata gen. et sp. nov. A parsimony analysis of fossil and extant pipoid frogs indicates that Singidella is more closely related to African Hymenochirus and Pseudhymenochirus than to South American Pipa . It also provides weak support for the sister-group relationship of Singidella and the bizarre Late Cretaceous Pachycentrata taqueti (replacement name for Pachybatrachus taqueti ) from Niger, although the incomplete preservation of Pachycentrata precludes thorough comparisons. This record indicates that prior to the rifting in the Miocene the distribution of pipines extended into eastern Africa where they do not occur today.     

Novel azolyl-(phenylmethyl)]aryl/heteroarylamines: potent CYP26 inhibitors and enhancers of all-trans retinoic acid activity in neuroblastoma cells

The synthesis and potent inhibitory activity of novel 4-[(imidazol-1-yl and triazol-1-yl)(phenyl)methyl]aryl-and heteroaryl amines versus a MCF-7 CYP26A1 cell assay is described. Biaryl imidazole ([4-(imidazol-1-yl-phenyl-methyl)-phenyl]-naphthalen-2-yl-amine (8), IC(50)=0.5 microM; [4-(imidazol-1-yl-phenyl-methyl)-phenyl]-indan-5-yl-amine (9), IC(50)=1.0 microM) and heteroaryl imidazole derivatives ((1H-benzoimidazol-2-yl)-{4-[(5H-imidazol-1-yl)-phenyl-methyl]-phenyl}-amine (15), IC(50)=2.5 microM; benzooxazol-2-yl-{4-[(5H-imidazol-1-yl)-phenyl-methyl]-phenyl}-amine (16), IC(50)=0.9 microM; benzothiazol-2-yl-{4-[(5H-imidazol-1-yl)-phenyl-methyl]-phenyl}-amine (17), IC(50)=1.5 microM) were the most potent CYP26 inhibitors. Using a CYP26A1 homology model differences in activity were investigated. Incubation of SH-SY5Y human neuroblastoma cells with the imidazole aryl derivative 8, and the imidazole heteroaryl derivatives 16 and 17 potentiated the atRA-induced expression of CYP26B1. These data suggest that further structure-function studies leading to clinical development are warranted.     

The role of riboflavin in decolourisation of Congo red and bioelectricity production using <Emphasis Type="Italic">Shewanella oneidensis</Emphasis>-MR1 under MFC and non-MFC conditions

Dissimilatory metal reducing bacteria can exchange electrons extracellularly and hold great promise for their use in simultaneous wastewater treatment and electricity production. This study investigated the role of riboflavin, an electron carrier, in the decolourisation of Congo red in microbial fuel cells (MFCs) using Shewanella oneidensis MR-1 as a model organism. The contribution of the membrane-bound protein MtrC to the decolourisation process was also investigated. Within the range of riboflavin concentrations tested, 20 µM was found to be the best with >95% of the dye (initial concentration 200 mg/L) decolourised in MFCs within 50 h compared to 90% in the case where no riboflavin was added. The corresponding maximum power density was 45 mW/m². There was no significant difference in the overall decolourisation efficiencies of Shewanela oneidensis MR-1 ΔMtrC mutants compared to the wild type. However, in terms of power production the mutant produced more power (P_max 76 mW/m²) compared to the wild type (P_max 46 mW/m²) which was attributed to higher levels of riboflavin secreted in solution. Decolourisation efficiencies in non-MFC systems (anaerobic bottles) were similar to those under MFC systems indicating that electricity generation in MFCs does not impair dye decolourisation efficiencies. The results suggest that riboflavin enhances both decolourisation of dyes and simultaneous electricity production in MFCs.     

Statistical Optimization of Culture Variables for Enhancing Agarase Production by <Emphasis Type="Italic">Dendryphiella arenaria</Emphasis> Utilizing <Emphasis Type="Italic">Palisada perforata</Emphasis> (Rhodophyta) and Enzymatic Saccharification of the Macroalgal Biomass

Agarase is a promising biocatalyst for several industrial applications. Agarase production was evaluated by the marine fungus Dendryphiella arenaria utilizing Palisada perforata as a basal substrate in semi-solid state fermentation. Seaweed biomass, glucose, and sucrose were the most significant parameters affecting agarase production, and their levels were further optimized using Box-Behnken design. The maximum agarase activity was 7.69 U/mL. Agarase showed a degree of thermostability with half-life of 99 min at 40 °C, and declining to 44.72 min at 80 °C. Thermodynamics suggested an important process of protein aggregation during thermal inactivation. Additionally, the enzymatic saccharification of the seaweed biomass using crude agarase was optimized with respect to biomass particle size, solid/liquid ratio, and enzyme loadings. The amount of biosugars obtained after optimization was 26.15 ± 1.43 mg/g. To the best of our knowledge, this is the first report on optimization of agarase in D. arenaria.