The response of nutrient assimilation and biochemical composition of Arctic seaweeds to a nutrient input in summer

Twenty-one species of macroalgae (four Chlorophyta, eight Rhodophyta, and nine Phaeophyta) from the Kongsfjord (Norwegian Arctic) were examined for their response to nutrient enrichment (nitrate and phosphate) in the summer period. The enzymatic activities related to nutrient assimilation, external carbonic anhydrase (CAext, EC 4.2.1.1), nitrate reductase (NR, EC 1.6.6.1), and alkaline phosphatase (AP, EC 3.1.3.1), as well as the biochemical composition (total C and N, soluble carbohydrates, soluble proteins, and pigments) were measured. CAext activity was present in all species, and showed a general decrease after nutrient enrichment. Inversely, NR activity increased in most of the species examined. Changes in pigment ratios pointed to the implication of light harvesting system in the acclimation strategy. Despite enzymatic and pigmentary response, the Arctic seaweeds can be regarded as not being N-limited even in summer, as shown by the slight effect of nutrient enrichment on biochemical composition. The exception being the nitrophilic species Monostroma arcticum and, to a lesser extent, Acrosiphonia sp. For the rest of the species studied, changes in total internal C and N, soluble proteins, soluble carbohydrates, pigment content, and the internal pool of inorganic N were recorded only for particular species and no general pattern was shown. Acclimation to unexpected nutrient input seemed to ensure the maintenance of a stable biomass composition, rather than an optimized use of the newly available resource (except for the nitrophilic species). This indicates a high degree of resilience of the algal community to a disruption in the natural nutrient availability pattern.     

Free brownian motion of individual lipid molecules in biomembranes

The mobility of phospolipids in free-standing and supported membranes was investigated on the level of individual molecules. For the analysis of trajectories a new statistical treatment was developed that permitted us to clearly distinguish different types of diffusional motion. A freely diffusing subfraction of lipids within supported membranes was identified. Its mobility was characterized by a mean lateral diffusion constant of D(supp) = 4.6 &mgr;m(2)/s. In comparison, the mobility of lipids embedded in "free-standing" planar membranes yielded an increase in the mean diffusion constant by a factor of 4.5, D(free) = 20.6 &mgr;m(2)/s. This increase is attributed to the ultrathin (</=1 nm) lubricating water layer between membranes and glass support.     

Changes in rainfall level and litter stoichiometry affect aquatic community and ecosystem processes in bromeliad phytotelmata

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Isolation and Partial Characterization of Antifungal Metabolites Produced by <Emphasis Type="Italic">Bacillus</Emphasis> sp. IBA 33

Antifungal proteins produced by Bacillus sp. IBA 33 were purified by ammonium sulfate precipitation and DEAE-Sephacel column chromatography. The two purified proteins inhibited the growth of Geotrichum candidum, the sour rot disease agent in lemon. The proteins were stable at 20 (3 months), 40, 60 and 100°C (30 min) and remained active after sterilization at 121°C for 15 min. Their hydrophobic nature was proved and when were developed with ninhydrin they did not show any free amino groups. The infrared spectrum showed vibrational modes corresponding to peptide, ester or ketone links and saturated CH links corresponding to long chain fatty acids. UV scan spectroscopy showed tyrosine and or tryptophan amino acids in their composition. The remarkable thermo-resistance of proteins may be a good feature to be used in the development of a new biocontrol method of Geotrichum candidum.     

Single amino acid supplementation in aminoacidopathies: a systematic review

Aminoacidopathies are a group of rare and diverse disorders, caused by the deficiency of an enzyme or transporter involved in amino acid metabolism. For most aminoacidopathies, dietary management is the mainstay of treatment. Such treatment includes severe natural protein restriction, combined with protein substitution with all amino acids except the amino acids prior to the metabolic block and enriched with the amino acid that has become essential by the enzymatic defect. For some aminoacidopathies, supplementation of one or two amino acids, that have not become essential by the enzymatic defect, has been suggested. This so-called single amino acid supplementation can serve different treatment objectives, but evidence is limited. The aim of the present article is to provide a systematic review on the reasons for applications of single amino acid supplementation in aminoacidopathies treated with natural protein restriction and synthetic amino acid mixtures.     

Regenerative potential of human muscle stem cells in chronic inflammation

Introduction

Chronic inflammation is a profound systemic modification of the cellular microenvironment which could affect survival, repair and maintenance of muscle stem cells. The aim of this study was to define the role of chronic inflammation on the regenerative potential of satellite cells in human muscle.

Methods

As a model for chronic inflammation, 11 patients suffering from rheumatoid arthritis (RA) were included together with 16 patients with osteoarthritis (OA) as controls. The mean age of both groups was 64 years, with more females in the RA group compared to the OA group. During elective knee replacement surgery, a muscle biopsy was taken from the distal musculus vastus medialis. Cell populations from four RA and eight OA patients were used for extensive phenotyping because these cell populations showed no spontaneous differentiation and myogenic purity greater than 75% after explantation.

Results

After mononuclear cell explantation, myogenic purity, viability, proliferation index, number of colonies, myogenic colonies, growth speed, maximum number of population doublings and fusion index were not different between RA and OA patients. Furthermore, the expression of proteins involved in replicative and stress-induced premature senescence and apoptosis, including p16, p21, p53, hTERT and cleaved caspase-3, was not different between RA and OA patients. Mean telomere length was shorter in the RA group compared to the OA group.

Conclusions

In the present study we found evidence that chronic inflammation in RA does not affect the in vitro regenerative potential of human satellite cells. Identification of mechanisms influencing muscle regeneration by modulation of its microenvironment may, therefore, be more appropriate.     

Croton balsensis (Euphorbiaceae), a new species from the Balsas Depression, Mexico

Croton balsensis (Euphorbiaceae), a new species endemic to the Balsas Depression of southern Mexico, is described and illustrated. It occurs in the states of Guerrero, Morelos, and Puebla, growing in tropical deciduous forest at elevations from 450 to 1850m. It is best accommodated inCroton sect.Cascarilla. The Mexican species of this section are often quite similar, butC. balsensis is readily separated from related species by the possession of echinate ovaries and fruits.

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Resumen  Se describe e ilustraCroton balsensis. Es endémica de la cuenca del río Balsas en el sur de México. Crece en los estados de Guerrero, Morelos y Puebla a altitudes de 450 a 1850 m en bosque tropical caducifolio. Pertenece aCroton sect.Cascarilla. Las especies mexicanas de esta sección por lo general son parecidas yC. balsensis se distingue por tener ovarios y frutos equinados.

     

Field site selection: getting it right first time around

The selection of suitable field sites for integrated control of Anopheles mosquitoes using the sterile insect technique (SIT) requires consideration of the full gamut of factors facing most proposed control strategies, but four criteria identify an ideal site: 1) a single malaria vector, 2) an unstructured, relatively low density target population, 3) isolation of the target population and 4) actual or potential malaria incidence. Such a site can exist in a diverse range of situations or can be created. Two contrasting SIT field sites are examined here: the desert-flanked Dongola Reach of the Nile River in Northern State, Sudan, where malaria is endemic, and the island of La Reunion, where autochthonous malaria is rare but risk is persistent. The single malaria-transmitting vector at both sites is Anopheles arabiensis. In Sudan, the target area is a narrow 500 km corridor stretching from the rocky terrain at the Fourth Cataract - just above the new Merowe Dam, to the northernmost edge of the species range, close to Egypt. Vector distribution and temporal changes in density depend on the Nile level, ambient temperature and human activities. On La Reunion, the An. arabiensis population is coastal, limited and divided into three areas by altitude and exposure to the trade winds on the east coast. Mosquito vectors for other diseases are an issue at both sites, but of primary importance on La Reunion due to the recent chikungunya epidemic. The similarities and differences between these two sites in terms of suitability are discussed in the context of area-wide integrated vector management incorporating the SIT.     

Host-specific cues cause differential attractiveness of Kenyan men to the African malaria vector Anopheles gambiae

Background  

Many studies have suggested that variability in the attractiveness of humans to host-seeking mosquitoes is caused by differences in the make-up of body emanations, and olfactory signals in particular. Most investigations have either been laboratory-based, utilising odour obtained from sections of the body, or have been done in the field with sampling methods that do not discriminate between visual, physical and chemical cues of the host. Accordingly, evidence for differential attractiveness based on body emanations remains sparse in spite of the far-reaching epidemiological implications of this phenomenon.     

FIGENIX: Intelligent automation of genomic annotation: expertise integration in a new software platform

Background  

Two of the main objectives of the genomic and post-genomic era are to structurally and functionally annotate genomes which consists of detecting genes' position and structure, and inferring their function (as well as of other features of genomes). Structural and functional annotation both require the complex chaining of numerous different software, algorithms and methods under the supervision of a biologist. The automation of these pipelines is necessary to manage huge amounts of data released by sequencing projects. Several pipelines already automate some of these complex chaining but still necessitate an important contribution of biologists for supervising and controlling the results at various steps.