Competitive interactions between four foliose lichens on north and south facing rock surfaces

Competition between four foliose lichen species which have distinct aspect distributions on slate rock in South Gwynedd, Wales, U.K. was studied in the field using a factorial experimental design. The lichens were grown as fragments glued to pieces of slate in monoculture and in two-, three- and four-species mixtures. The pieces of slate were placed to face a northerly or southerly direction. Growth in area (mm2) was used as a measure of performance in the experiment. The growth in area of Parmelia conspersa in south facing plots was not reduced in the presence of any of its competitors but its growth was reduced in the presence of Parmelia saxatilis in north facing plots. The growth of Parmelia glabratula ssp. fuliginosa was reduced in the presence of P. conspersa and P. saxatilis in south and north facing plots. Physcia orbicularis was reduced by P. conspersa in south facing plots and by both P. glabratula ssp. fuliginosa and P. saxatilis in north facing plots. The growth of P. saxatilis was increased by P. glabratula ssp. fuliginosa in south facing plots but was not reduced by any of its competitors in north facing plots. Significant two and three factor interactions suggested that the results from the three- and four-species mixtures were not always predictable from the results of the two-species mixtures. The results of the experiment may help to explain the existing aspect distribution of the four species on slate rock in South Gwynedd.

The postantibiotic effect of the carbapenem antibiotics on gram-negative bacteria

Postantibiotic effect (PAE) describes the suppression of microbial growth occurring after a short exposure to an antimicrobial agent. PAE appears to be a property of the majority of antimicrobial agents and is demonstrated by a wide variety of microorganisms. At present, carbapenems and penems are the only members of the -lactam group of antimicrobial agents that exhibit a significant PAE on Gram-negative bacilli. A standardised method was developed to evaluate the in vitro PAE of three carbapenems; imipenem, meropenem and biapenem on Gram-negative bacteria under reproducible laboratory conditions that partially mimicked those occurring in vivo. The effects on carbapenem PAE of the method of antimicrobial removal, concentration, exposure duration, inoculum size, inoculum growth phase, multiple exposures and pooled human serum were determined. Additionally, the reproducibility, susceptibility prior to and after PAE determination and inter-strain variation of carbapenem PAE were evaluated. The method developed determined PAE by utilising viable counts and demonstrated carbapenem PAE to be reproducible, constant over successive exposures, dependent on genera, concentration, duration of exposure, inoculum size and growth phase. In addition, carbapenem PAE was not significantly effected either by agitation, the antimicrobial removal method or the viable count diluent. At present, the mechanism underlying PAE is undetermined. It is thought to be due to either the prolonged persistence of the antimicrobial at the cellular site of action or the true recovery period from non-lethal damage. Increasing the L-lysine concentration and salinity at recovery decreased and increased the carbapenem and imipenem PAE of Pseudomonas aeruginosa, respectively. In addition, no apparent change was observed in the production of virulence factors by P.aeruginosa in PAE phase. However, alterations in cell morphology were observed throughout PAE phase, and the reappearance of normal cell morphology corresponded to the duration of PAE determined by viable count. Thus, the recovery of the penicillin binding protein target enzymes appears to be the mechanism behind carbapenem PAE in P. aeruginosa.

The surface of Pseudomonas aeruginosa in cystic fibrosis lung infection

Chronic experimental lung infection in rats was induced by intratracheal inoculation of agar beads containing Pseudomonas aeruginosa. Bacteria were recovered directly without subculture from the lungs of rats at 14 days post-infection and the outer membrane (OM) antigens were studied. The results indicated that bacteria grew under iron-restricted conditions as revealed by the expression of several iron-regulated membrane proteins (IRMPs) which could also be observed when the isolate was grown under iron-depleted conditions in laboratory media. The antibody response to P. aeruginosa OM protein antigens was investigated by immunoblotting with serum and lung fluid from infected rats. These fluids contained antibodies to all the major OM proteins, including the IRMPs, and protein H1. Results obtained using immunoblotting and enzyme-linked immunosorbent assay indicated that lipopolysaccharide (LPS) was the major antigen recognised by antibodies in sera from infected rats. The animal model was used to follow the development of the immune response to P. aeruginosa protein and LPS antigens. Immunoblotting was used to investigate the antigens recognised by antibodies in sequential serum samples. An antibody response to the IRMPs and OM proteins D, E, G and H1 and alao to rough LPS was detected as early as 4 days post-infection. Results obtained using immunoblotting and crossed immunoelectrophoresis techniques indicated that there was a progressive increase in the number of P. aeruginosa antigens recognised by antibodies in these sera. Both iron and magnesium depletion influenced protein H1 production. Antibodies in sera from patients with infections due to P. aeruginosa reacted with this antigen. Results obtained using quantitative gas-liquid chromatographic analysis indicated that growth phase and magnesium and iron depletion also affected the amount of LPS fatty acids, produced by P. aeruginosa. The silver stained SDS-polyacrylamide gels of proteinase K digested whole cell lysates of P. aeruginosa indicated that the O-antigen and core LPS were both affected by growth phase and specific nutrient depletion.

The Perturbed Generalized Tikhonov's Algorithm

We work on the research of a zero of a maximal monotone operator on a real Hilbert space. Following the recent progress made in the context of the proximal point algorithm devoted to this problem, we introduce simultaneously a variable metric and a kind of relaxation in the perturbed Tikhonov’s algorithm studied by P. Tossings. So, we are led to work in the context of the variational convergence theory.

Polynomial Expansions for Solutions of Higher-Order Bessel Heat Equation in Quantum Calculus

Mathematics Subject Class.: 33C10,33D60,26D15,33D05,33D15,33D90

Large Distinct Part Sizes in a Random Integer Partition

A partition of a positive integer n is a way of writing it as the sum of positive integers without regard to order; the summands are called parts. The number of partitions of n, usually denoted by p(n), is determined asymptotically by the famous partition formula of Hardy and Ramanujan [5]. We shall introduce the uniform probability measure P on the set of all partitions of n assuming that the probability 1/p(n) is assigned to each n-partition. The symbols E and V ar will be further used to denote the expectation and variance with respect to the measure P . Thus, each conceivable numerical characteristic of the parts in a partition can be regarded as a random variable.

The effect of climate change on the potential distribution of the European Phlebotomus species

Our study intended to explore the potential distributionshif of Phlebotomusariasi, P. neglectus, P. perfiliewi, P. perniciosus, and P. tobbi, and some other sandfly species: P. papatasi, P. sergenti, and P. similis. We used climate envelope modeling (CEM) method to determine the ecological requirements of the species and to model the potential distribution for three periods (1961-1990, 2011-2040, and 2041- 2070). We found that by the end of the 2060’s the Southern UK, Germany, entire France and also the western part of Poland can be colonized by sandfly species, mostly by P. ariasi and P. pernicosus. P. ariasishowe the greatest potential northward expansion, from 49°N to 59°N. For all of the studied sand fly species the entire Mediterranean Basin, the Balkan Peninsula, the Carpathian Basin, and northern coastline of the Black Sea are potentially suitable. The length of the predicted active period of the vectors will increase with one or two months.

The effect of climate change on the potential distribution of the European Phlebotomus species and the parasite Leishmania infantum in 2011-2070. A climate envelope modeling approach

Aims: In the Mediterranean areas of Europe, leishmanisasis is one of the most emerging vector-borne diseases. Members of genus Phlebotomus are the primary vectors of the genus Leishmania. To track the human health effect of climate change it is a very important interdisciplinary question to study whether the climatic requirements and geographical distribution of the vectors of human pathogen organisms correlate with each other. Our study intended to explore the potential effects of ongoing climate change, in particular through a potential upward altitudinal and latitudinal shift of the distribution of the parasite Leishmania infantum, its vectors Phlebotomus ariasi, P. neglectus, P. perfiliewi, P. perniciosus, and P. tobbi, and some other sandfly species: P. papatasi, P. sergenti, and P. similis. Methods: By using a climate envelope modelling (CEM) method we modelled the current and future (2011-2070) potential distribution of 8 European sandfly species and L. infantum based on the current distribution using the REMO regional climate model. Results: We found that by the end of the 2060’s most parts of Western Europe can be colonized by sandfly species, mostly by P. ariasi and P. pernicosus. P. ariasi showed the greatest potential northward expansion. For all the studied vectors of L. infantum the entire Mediterranean Basin and South-Eastern Europe seemed to be suitable. L. infantum can affect the Eastern Mediterranean, without notable northward expansion. Our model resulted 1 to 2 months prolongation of the potentially active period of P. neglectus P. papatasi and P. perniciosus for the 2060’s in Southern Hungary. Conclusion: Our findings confirm the concerns that leishmanisais can become a real hazard for the major part of the European population to the end of the 21th century and the Carpathian Basin is a particularly vulnerable area.

Európai lepkeszúnyog fajok potenciális elterjedése a 21. században

Leishmaniasis is a typical vectorial disease transmitted by Psycodidae vectors (Lutzomyans, Phlebotomus species). The worldwide observed 1,5-2 million new cases and 60,000 death caused by Leishmania parasites per year make leishmaniasis is one of the most important vectorial disease in the tropicals and warm temperate areas of the World. In the human environment dogs and cats are the most important hosts of the different leishmania agents. The different leishmania species cause symptomatically cutan or visceral disease forms, but many other type of the disease has recognised. Phlebotomus species are sensitive to climatic patterns, they require hight relative air humidity, mild winters and long and warm vegetation period, but the environmental requirements of the species naturally is not the same. Due to climate change in the near future the climate of Western and Central Europe could allow the colonisation of these highly populated areas with also the vectors and the parasites. Our aim was to analyse the environmental patterns of the current distribution area of 8 important sand flies (P. ariasi, P. perniciosus, P. perfiliewi, P. papatasi, P. tobbi, P. neglectus, P. similis and P. sergenti) using the 1960-1990 period’s climate as reference. Using climate envelope modeling we determined these climatic characters and using the REMO climate projection we created the recent and the near-future (2011-2040 and 2041-2070) potential distribution area of the sand flies. The current known area of many Phlebotomus species restricted either to the western or to the eastern Mediterranean Basin. We found that their climatic requirements are could not explain their segregation, it is maybe the consequence of their evolutionary history (geographical barriers and paleoclimatic history). By the end of the 2060’s most parts of Western Europe can be colonized by sand flies, mostly by P. ariasi and P. pernicosus. P. ariasi showed the greatest potential northward expansion. Our model resulted 1 to 2 months prolongation of the potentially active period of P. neglectus P. papatasi and P. perniciosus for the 2070’s in Southern Hungary. As the climate becomes drier and warmer, sand flies will occupy more and more parts of Hungary. Our findings confirm the concerns that leishmanisais can become a real hazard for the major part of the European population to the end of the 21th century and the Carpathian Basin is a particularly vulnerable area.

Experimental nutrient enrichment causes complex changes in seagrass, microalgae, and macroalgae community structure in Florida Bay

We evaluated how changes in nutrient supply altered the composition of epiphytic and benthic microalgal communities in a Thalassia testudinum (turtle grass) bed in Florida Bay. We established study plots at four sites in the bay and added nitrogen (N) and phosphorus (P) to the sediments in a factorial design. After 18, 24, and 30 months of fertilization we measured the pigment concentrations in the epiphytic and benthic microalgal assemblages using high performance liquid chromatography. Overall, the epiphytic assemblage was P-limited in the eastern portion of the bay, but each phototrophic group displayed unique spatial and temporal responses to N and P addition. Epiphytic chlorophyll a, an indicator of total microalgal load, and epiphytic fucoxanthin, an indicator of diatoms, increased in response to P addition at one eastern bay site, decreased at another eastern bay site, and were not affected by P or N addition at two western bay sites. Epiphytic zeaxanthin, an indicator of the cyanobacteria/coralline red algae complex, and epiphytic chlorophyll b, an indicator of green algae, generally increased in response to P addition at both eastern bay sites but did not respond to P or N addition in the western bay. Benthic chlorophyll a, chlorophyll b, fucoxanthin, and zeaxanthin showed complex responses to N and P addition in the eastern bay, suggesting that the benthic assemblage is limited by both N and P. Benthic assemblages in the western bay were variable over time and displayed few responses to N or P addition. The contrasting nutrient limitation patterns between the epiphytic and benthic communities in the eastern bay suggest that altering nutrient input to the bay, as might occur during Everglades restoration, can shift microalgal community structure, which may subsequently alter food web support for upper trophic levels.

Crayfish assemblage shifts in a large drought-prone wetland: the roles of hydrology and competition

1. Faster growing, larger and/or more aggressive crayfish species are predicted to dominate permanent waterbodies. We tested this prediction using a 9 year dataset for two species of crayfish (Procambarus alleni and Procambarus fallax) co-existing in a sub-tropical flowing slough in southern Florida. Using a series of laboratory and mesocosm experiments we also compared life history traits and performance of the respective species to test mechanisms that could explain dominance shifts in the local crayfish assemblages. 2. Over the 9-year period, P. alleni densities were the greatest in shallower, shorterhydroperiod areas bordering the slough, while P. fallax densities were higher in deeper, longer-hydroperiod central areas. These areas were separated by 0.8–2 km of continuous wetland with no apparent barriers to movement between them. 3. Density of P. fallax was not strongly affected by any measures of hydrological variation, while P. alleni density increased with more severe drought conditions. Following the strongest droughts, P. alleni colonized areas in the centre of the slough where they had been absent or scarce in wetter years. 4. We conducted experiments to compare growth rates, drought tolerance, and competitive dominance of these species. P. alleni survived drought conditions better, had higher growth rates, and was the dominant competitor for space and food. While drought probably limits P. fallax in the drier slough habitats, neither drought sensitivity nor interspecific competition with P. fallax can explain decreases of P. alleni with wetter conditions. 5. Our results indicate that a competition-colonization tradeoff cannot explain the crayfish compositional dynamics in this wetland because P. alleni is both the best competitor and the best at surviving in and colonizing areas with the strongest droughts. Future attention should focus on the potential for selective effects of predators that co-vary with hydrology. 6. The traits (large size, fast growth, competitive dominance) exhibited by P. alleni, which is absent in long-hydroperiod wetlands, are those exhibited by dominant crayfish in permanent lakes and streams containing fish. Although these traits make crayfish less vulnerable to fish in some lakes and streams, life-history models of community structure across permanence gradients suggest the opposite traits should be favoured for co-existence with fish.

Ecosystem Structure and Function Still Altered Two Decades After Short-Term Fertilization of a Seagrass Meadow

An oligotrophic phosphorus (P) limited seagrass ecosystem in Florida Bay was experimentally fertilized in a unique way. Perches were installed to encourage seabirds to roost and deliver an external source of nutrients via defecation. Two treatments were examined: (1) a chronic 23-year fertilization and (2) an earlier 28-month fertilization that was discontinued when the chronic treatment was initiated. Because of the low mobility of P in carbonate sediments, we hypothesized long-term changes to ecosystem structure and function in both treatments. Structural changes in the chronic treatment included a shift in the dominant seagrass species from Thalassia testudinum to Halodule wrightii, large increases in epiphytic biomass and sediment chlorophyll-a, and a decline in species richness. Functional changes included increased benthic metabolism and quantum efficiency. Initial changes in the 28-month fertilization were similar, but after 23 years of nutrient depuration T. testudinum has reestablished itself as the dominant species. However, P remains elevated in the sediment and H. wrightii has maintained a presence. Functionally the discontinued treatment remains altered. Biomass exceeds that in the chronic treatment and indices of productivity, elevated relative to control, are not different from the chronic fertilization. Cessation of nutrient loading has resulted in a superficial return to the pre-disturbance character of the community, but due to the nature of P cycles functional changes persist.

Interactions between nutrient availability and hydroperiod shape macroinvertebrate communities in Florida Everglades marshes

Hydroperiod and nutrient status are known to influence aquatic communities in wetlands, but their joint effects are not well explored. I sampled floating periphyton mat and flocculent detritus (floc) infaunal communities using 6-cm diameter cores at short- and long-hydroperiod and constantly inundated sites across a range of phosphorus (P) availability (total phosphorus in soil, floc and periphyton). Differences in community structure between periphyton and floc microhabitats were greater than any variation attributable to hydroperiod, P availability, or other spatial factors. Multivariate analyses indicated community structure of benthic-floc infauna was driven by hydroperiod, although crowding (no. g−1 AFDM) of individual taxa showed no consistent responses to hydroperiod or P availability. In contrast, community structure of periphyton mat infauna was driven by P availability, while densities of mat infauna (no. m−2) were most influenced by hydroperiod (+correlations). Crowding of mat infauna increased significantly with P availability in short-hydroperiod marshes, but was constant across the P gradient in long-hydroperiod marshes. Increased abundance of floating-periphyton mat infauna with P availability at short-hydroperiod sites may result from a release from predation by small fish. Community structure and density were not different between long-hydroperiod and constantly inundated sites. These results have implications for the use of macroinvertebrates as indicators of water quality in wetlands and suggest the substrate sampled can influence interpretation of ecological responses observed in these communities.

Segregation of Palaemonid Shrimp Along an Everglades Estuarine Gradient: Do Multiple Species Have Similar Trophic Function?

Variation in physical gradients and production along estuaries can alter species compositions. Spatiotemporal variation in abundance and distribution of palaemonid shrimp species was investigated in relation to seasonal freshwater inputs and salinity in the Shark River Estuary, Everglades National Park, Florida, USA. Using trapping techniques, multiple sites were sampled repeatedly extending from the headwaters to the Gulf of Mexico. Stable isotope analyses were also performed on a subset of samples. Five palaemonid species occurred in the samples: Palaemonetes paludosus (Gibbes, 1850), Palaemonetes pugio (Holthuis, 1949), Palaemonetes intermedius (Holthuis, 1949), Palaemon floridanus (Chace, 1942), and Leander paulensis(Ortmann, 1897). Overall, shrimp catches in traps doubled in the dry season. Catches in the upper estuary were dominated by P.paludosus, particularly in the wet season, while catch per unit effort at the most downstream and highest salinity sites were dominated by P. floridanus. At mid-estuary, several species co-occurred. δ15n analyses revealed that most species filled similar roles in the community, with the exception of P. paludosus, which shifted from enrichment in the dry season to depletion in the wet season as it expanded downstream in the estuary. Palaemonid δ13C values varied between sites and seasons, with shrimp in upstream sites being more depleted. These data suggest that changes in salinity regimes resulting from Everglades restoration efforts may result in species replacement, with potential implications for trophic dynamics.

Avaliação do potencial da fibra e casca de coco maduro, casca de coco verde e cacto pré-tratados visando à produção de etanol

The present work investigated the potential of different residual lignocellulosic materials generated in rural and urban areas (coconut fibre mature, green coconut shell and mature coconut shell), and vegetable cultivated in inhospitable environments (cactus) aimed at the production of ethanol, being all materials abundant in the Northeast region of Brazil. These materials were submitted to pretreatments with alkaline hydrogen peroxide followed by sodium hydroxide (AHP-SHP), autohydrolysis (AP), hydrothermal catalyzed with sodium hydroxide (HCSHP) and alkali ethanol organosolv (AEOP). These materials pretreated were submitted to enzymatic hydrolysis and strategies of simultaneous saccharification and fermentation (SSF) and saccharification and fermentation semi-simultaneous (SSSF) by Saccharomyces cerevisiae, Zymomonas mobilis and Pichia stipitis. It was also evaluated the presence of inhibitory compounds (hydroxymethylfurfural, furfural, acetic acid, formic acid and levulinic acid) and seawater during the fermentative process. Materials pretreated with AHP-SHP have resulted in delignification of the materials in a range between 54 and 71%, containing between 51.80 and 54.91% of cellulose, between 17.65 and 28.36% of hemicellulose, between 7.99 and 10.12% of lignin. Enzymatic hydrolysis resulted in the conversions in glucose between 68 and 76%. Conversion yields in ethanol using SSF and SSSF for coconut fibre mature pretreated ranged from 0.40 and 0.43 g/g, 0.43 and 0.45 g/g, respectively. Materials pretreated by AP showed yields of solids between 42.92 and 92.74%, containing between 30.65 and 51.61% of cellulose, 21.34 and 41.28% of lignin. Enzymatic hydrolysis resulted in glucose conversions between 84.10 and 92.52%. Proceeds from conversion into ethanol using green coconut shell pretreated, in strategy SSF and SSSF, were between 0.43 and 0.45 g/g. Coconut fibre mature pretreated by HCSHP presented solids yields between 21.64 and 60.52%, with increased in cellulose between 28.40 and 131.20%, reduction of hemicellulose between 43.22 and 69.04% and reduction in lignin between 8.27 and 89.13%. Enzymatic hydrolysis resulted in the conversion in glucose of 90.72%. Ethanol yields using the SSF and SSSF were 0.43 and 0.46 g/g, respectively. Materials pretreated by AEOP showed solid reductions between 10.75 and 43.18%, cellulose increase up to 121.67%, hemicellulose reduction up to 77.09% and lignin reduced up to 78.22%. Enzymatic hydrolysis resulted in the conversion of glucose between 77.54 and 84.27%. Yields conversion into ethanol using the SSF and SSSF with cactus pretreated ranged from 0.41 and 0.44 g/g, 0.43 and 0.46 g/g, respectively. Fermentations carried out in bioreactors resulted in yields and ethanol production form 0.42 and 0.46 g/g and 7.62 and 12.42 g/L, respectively. The inhibitory compounds showed negative synergistic effects in fermentations performed by P. stipitis, Z. mobilis and S. cerevisiae. Formic acid and acetic acid showed most significant effects among the inhibitory compounds, followed by hydroxymethylfurfural, furfural and levulinic acid. Fermentations carried out in culture medium diluted with seawater showed promising results, especially for S. cerevisiae (0.50 g/g) and Z. mobilis (0.49 g/g). The different results obtained in this study indicate that lignocellulosic materials, pretreatments, fermentative processes strategies and the microorganisms studied deserve attention because they are promising and capable of being used in the context of biorefinery, aiming the ethanol production.