Candidemia by Species of the Candida parapsilosis Complex in Children’s Hospital: Prevalence, Biofilm Production and Antifungal Susceptibility

Opportunistic infections are an increasingly common problem in hospitals, and the yeast Candida parapsilosis has emerged as an important nosocomial pathogen. The aims of this study were to determine and compare (i) the prevalence rate among C. parapsilosis complex organisms isolated from blood in a public children’s hospital in São Paulo state, (ii) the ability of the complex C. parapsilosis species identified to produce biofilm and (iii) the antifungal susceptibility profiles. Forty-nine (49) specimens of isolated blood yeast were analyzed, previously identified as C. parapsilosis by conventional methods. After the molecular analysis, the isolates were characterized as C. parapsilosis sensu stricto (83.7 %), C. orthopsilosis (10.2 %) and C. metapsilosis (6.1 %). All species were able to form biofilm. The species with the highest biofilm production was C. parapsilosis sensu stricto, followed by C. orthopsilosis and further by C. metapsilosis. All of the strains have demonstrated similar susceptibility to fluconazole, caspofungin, voriconazole, cetoconazole and 5-flucytosine. Only one strain of C. parapsilosis was resistant to amphotericin B. Regarding itraconazole, 66.6 and 43.9 % isolates of C. metapsilosis and C. parapsilosis, respectively, have demonstrated to be susceptible dose-dependent, with one isolate of the latter species resistant to the drug. Candida parapsilosis sensu stricto has demonstrated to be the less susceptible, mainly to amphotericin B, caspofungin and “azoles” such as fluconazole. Therefore, C. metapsilosis and C. orthopsilosis are still involved in a restricted number of infections, but these data have become essential for there are very few studies of these species in Latin America.     

Female preference for blue in Japan blue guppies (Poecilia reticulata)

Guppies (Poecilia reticulata) are widely used as a model species in mate choice studies. Although native to South America, guppies have been introduced to natural water bodies in disparate regions of the globe. Here, for the first time, we examine guppies from one such introduced population in Japan where males have evolved a predominantly blue color pattern. Previous studies of wild-type guppies have shown blue to play a relatively minor role in the mate choice decisions of females compared to other traits, such as orange, and the importance of blue is not universally supported by all studies. The Japanese population therefore presents an ideal opportunity to re-examine the potential significance of blue as a mate choice cue in guppies. Mate choice experiments, in which female Japan blue guppies were given a choice between pairs of males that differed in their area of blue coloration but were matched for other traits, revealed that females prefer males with proportionately larger amounts of blue in their color patterns. We discuss possible factors, including sexual and ecological selection, which may have led to the evolution of unusually large areas of blue at the expense of other colors in Japan blue guppies. However, further studies are needed to distinguish between these scenarios.     

Subsurface behavior of bottlenose dolphins (Tursiops truncatus) interacting with fish trawl nets in northwestern Australia: Implications for bycatch mitigation

Most studies of delphinid‐trawler interactions have documented the surface behavior of dolphins feeding on discarded bycatch, but not their subsurface behavior around demersal trawl gear. Using video cameras mounted inside trawl nets, we recorded the subsurface behavior of common bottlenose dolphins (Tursiops truncatus) in a demersal fish trawl fishery in northwestern Australia. Footage from 36 trawls across the fishery was analyzed to determine the extent of dolphin‐gear interactions and the behavior of dolphins inside the nets. Interaction rates were high, with dolphins present inside and outside the nets during 29 and 34 trawls, respectively, and for up to 99% of the trawl duration. The proportion of foraging behaviors exhibited inside the nets was higher than the proportions of traveling and socializing behaviors. Twenty‐nine individuals were identified inside the net, seven of which returned repeatedly within and between trawls and fishing trips, but were observed primarily in the same localized areas in which they were first recorded. Our results suggest that entering trawl nets may be a frequently occurring, yet specialized behavior exhibited by a small subset of trawler‐associated dolphins. We propose that gear modifications, not spatial or temporal adjustments to fishing effort, have the greatest potential to reduce dolphin bycatch.     

Dynamics of a biofouling community in finfish aquaculture: a case study from the South Adriatic Sea

Biofouling is one of the challenges that can strongly affect the finfish farm economy. Although several studies on biofouling in aquaculture have been conducted in the Mediterranean Sea, they focused on specific taxa or were limited to a particular period of sampling. The present study investigated for the first time the development, composition and variation in a biofouling community in a finfish farm with immersion time, season and depth. The results indicate that all these factors influence biofouling succession and recruitment. Moreover, the species that had a crucial role in structuring the community and in the farm cleaning activities were the ascidian Styela plicata and the bivalve Mytilus galloprovincialis. Compared with the literature data, the results highlight the heterogeneity in the composition of the biofouling present in the Mediterranean Sea. Moreover, such knowledge of the biofouling community could provide important information about management efforts and the costs that farmers will face when siting new fish farms.     

Evaluation of DNA extraction methods from complex phototrophic biofilms

Phototrophic biofilms are used in a variety of biotechnological and industrial processes. Understanding their structure, ie microbial composition, is a necessary step for understanding their function and, ultimately, for the success of their application. DNA analysis methods can be used to obtain information on the taxonomic composition and relative abundance of the biofilm members. The potential bias introduced by DNA extraction methods in the study of the diversity of a complex phototrophic sulfide-oxidizing biofilm was examined. The efficiency of eight different DNA extraction methods combining physical, mechanical and chemical procedures was assessed. Methods were compared in terms of extraction efficiency, measured by DNA quantification, and detectable diversity (16S rRNA genes recovered), evaluated by denaturing gradient gel electrophoresis (DGGE). Significant differences were found in DNA yields ranging from 116 ± 12 to 1893 ± 96 ng of DNA. The different DGGE fingerprints ranged from 7 to 12 bands. Methods including phenol–chloroform extraction after enzymatic lysis resulted in the greatest DNA yields and detectable diversity. Additionally, two methods showing similar yields and retrieved diversity were compared by cloning and sequencing. Clones belonging to members of the Alpha-, Beta- and Gamma- proteobacteria, Bacteroidetes, Cyanobacteria and to the Firmicutes were recovered from both libraries. However, when bead-beating was applied, clones belonging to the Deltaproteobacteria were also recovered, as well as plastid signatures. Phenol–chloroform extraction after bead-beating and enzymatic lysis was therefore considered to be the most suitable method for DNA extraction from such highly diverse phototrophic biofilms.     

Modelling root plasticity and response of narrow-leafed lupin to heterogeneous phosphorus supply

Background & Aims

Searching for root traits underpinning efficient nutrient acquisition has received increased attention in modern breeding programs aimed at improved crop productivity. Root models provide an opportunity to investigate root-soil interactions through representing the relationships between rooting traits and the non-uniform supply of soil resources. This study used simulation modelling to predict and identify phenotypic plasticity, root growth responses and phosphorus (P) use efficiency of contrasting Lupinus angustifolius genotypes to localised soil P in a glasshouse.

Methods

Two L. angustifolius genotypes with contrasting root systems were grown in cylindrical columns containing uniform soil with three P treatments (nil and 20 mg P kg^?1 either top-dressed or banded) in the glasshouse. Computer simulations were carried out with root architecture model ROOTMAP which was parameterized with root architectural data from an earlier published hydroponic phenotyping study.

Results

The experimental and simulated results showed that plants supplied with banded P had the largest root system and the greatest P-uptake efficiency. The P addition significantly stimulated root branching in the topsoil, whereas plants with nil P had relatively deeper roots. Genotype-dependent root growth plasticity in response to P supply was shown, with the greatest response to banded P.

Conclusions

Both experimental and simulation outcomes demonstrated that 1) root hairs and root proliferation increased plant P acquisition and were more beneficial in the localised P fertilisation scenario, 2) placing P deeper in the soil might be a more effective fertilisation method with greater P uptake than top dressing, and 3) the combination of P foraging strategies (including root architecture, root hairs and root growth plasticity) is important for efficient P acquisition from a localised source of fertiliser P.     

Historical climate‐human‐ecosystem interaction in East Africa: a review

The palaeoecological visibility of historical human impact on natural ecosystems in tropical East Africa is strongly impeded by an overriding dominant signature of climate change at decadal‐to‐millennial time scales. Better knowledge of the relative magnitude and timing of present and past human impact and climate variability is, however, instrumental to properly assess the resilience, and recovery potential, of East Africa's natural ecosystems. Here, we briefly review comprehensive previous attempts to assess past ecosystem responses to climate change and human impact. We further discuss some key issues of climate‐human‐ecosystem relationships in a multidisciplinary framework and address some future challenges and outcomes, which may pave the way to a better understanding of past climate‐human‐ecosystem interaction‐ in tropical Africa.     

Bivariate and Multivariate Analyses of the Influence of Blood Variables of Patients Submitted to Roux-en-Y Gastric Bypass on the Stability of Erythrocyte Membrane against the Chaotropic Action of Ethanol

The stability of the erythrocyte membrane, which is essential for the maintenance of cell functions, occurs in a critical region of fluidity, which depends largely on its composition and the composition and characteristics of the medium. As the composition of the erythrocyte membrane is influenced by several blood variables, the stability of the erythrocyte membrane must have relations with them. The present study aimed to evaluate, by bivariate and multivariate statistical analyses, the correlations and causal relationships between hematologic and biochemical variables and the stability of the erythrocyte membrane against the chaotropic action of ethanol. The validity of this type of analysis depends on the homogeneity of the population and on the variability of the studied parameters, conditions that can be filled by patients who undergo bariatric surgery by the technique of Roux-en-Y gastric bypass since they will suffer feeding restrictions that have great impact on their blood composition. Pathway analysis revealed that an increase in hemoglobin leads to decreased stability of the cell, probably through a process mediated by an increase in mean corpuscular volume. Furthermore, an increase in the mean corpuscular hemoglobin (MCH) leads to an increase in erythrocyte membrane stability, probably because higher values of MCH are associated with smaller quantities of red blood cells and a larger contact area between the cell membrane and ethanol present in the medium.