Phytoplankton of the Amur River Estuary (Sea of Okhotsk) during the summer periods of 2005–2007

The qualitative composition of planktonic microalgae in the Amur River Estuary (in the Sea of Okhotsk) was studied in July 2005, June 2006, and June 2007. The biomass and abundance of phytoplankton were studied for the first time. The average cell density of the microalgae ranged from 194700 to 855100 cells/liter, being higher in 2006 than in 2005 and 2007. The average biomass of the community varied from 1.06 g/m³ in 2007 to 3.17 g/m³ in 2006. Analysis of the similarity of the species composition and cell density of the phytoplankton revealed two groups of stations: the first includes stations in the northern and central parts of the Amur Estuary; and the second includes stations in the southern and central parts. The first group was characterized by the predominance of freshwater diatoms and a high abundances of green and blue-green algae and the second group was characterized by the predominance of marine microalgae. The high cell density and biomass of phytoplankton were due to the increased nutrient input via the river runoff of the Amur.     

Acid-sensing ion channels in mouse olfactory bulb M/T neurons

The olfactory bulb contains the first synaptic relay in the olfactory pathway, the sensory system in which odorants are detected enabling these chemical stimuli to be transformed into electrical signals and, ultimately, the perception of odor. Acid-sensing ion channels (ASICs), a family of proton-gated cation channels, are widely expressed in neurons of the central nervous system. However, no direct electrophysiological and pharmacological characterizations of ASICs in olfactory bulb neurons have been described. Using a combination of whole-cell patch-clamp recordings and biochemical and molecular biological analyses, we demonstrated that functional ASICs exist in mouse olfactory bulb mitral/tufted (M/T) neurons and mainly consist of homomeric ASIC1a and heteromeric ASIC1a/2a channels. ASIC activation depolarized cultured M/T neurons and increased their intracellular calcium concentration. Thus, ASIC activation may play an important role in normal olfactory function.     

Worms and gills,plates and spines: the evolutionary origins and incredible disparity of deuterostomes revealed by fossils,genes, and development

Deuterostomes are the major division of animal life which includes sea stars, acorn worms, and humans, among a wide variety of ecologically and morphologically disparate taxa. However, their early evolution is poorly understood, due in part to their disparity, which makes identifying commonalities difficult, as well as their relatively poor early fossil record. Here, we review the available morphological, palaeontological, developmental, and molecular data to establish a framework for exploring the origins of this important and enigmatic group. Recent fossil discoveries strongly support a vermiform ancestor to the group Hemichordata, and a fusiform active swimmer as ancestor to Chordata. The diverse and anatomically bewildering variety of forms among the early echinoderms show evidence of both bilateral and radial symmetry. We consider four characteristics most critical for understanding the form and function of the last common ancestor to Deuterostomia: Hox gene expression patterns, larval morphology, the capacity for biomineralization, and the morphology of the pharyngeal region. We posit a deuterostome last common ancestor with a similar antero-posterior gene regulatory system to that found in modern acorn worms and cephalochordates, a simple planktonic larval form, which was later elaborated in the ambulacrarian lineage, the ability to secrete calcium minerals in a limited fashion, and a pharyngeal respiratory region composed of simple pores. This animal was likely to be motile in adult form, as opposed to the sessile origins that have been historically suggested. Recent debates regarding deuterostome monophyly as well as the wide array of deuterostome-affiliated problematica further suggest the possibility that those features were not only present in the last common ancestor of Deuterostomia, but potentially in the ur-bilaterian. The morphology and development of the early deuterostomes, therefore, underpin some of the most significant questions in the study of metazoan evolution.     

Successful strategies in size structured mixotrophic food webs

This study investigates how food web structures in aquatic microbial communities emerge based on different mixotrophic life strategies. Unicellular mixotrophic organisms that combine osmotrophy and primary production with phagotrophy account for significant amounts of primary production and bacterivory in marine environments, yet mixotrophs are still usually absent in large-scale biogeochemical models. We here present for the first time a thorough analysis of a food web model with a finely resolved structure in both cell size and foraging mode, where foraging mode is a strategy ranging from pure osmotrophy to pure phagotrophy. A trade-off for maximum uptake rates of mixotrophs is incorporated. We study how different factors determine the food web structure, here represented by the topology of the distribution of given amounts of total phosphorous over the cell size-foraging mode plane. We find that mixotrophs successfully coexist with foraging specialists (pure osmo- and phagotrophs) for a wide range of conditions, a result consistent with the observed prevalence of mixotrophs in recent oceanographic surveys. Mixotrophy trade-off and size-dependent parameters have a strong effect on the emerging community structure, stressing the importance of foraging mode and size considerations when working with microbial diversity and food web dynamics. The proposed model may be used to develop timely representations of mixotrophic strategies in larger biogeochemical ocean models.     

Enzymatic conversion of a sophorolipid into a glucose lipid

The diacetylated lactonic sophorolipid from Candida bombolica was converted into the deacetylated acidic form by alkaline hydrolysis and subsequently treated with several glycosidases. One of these enzymes, a hesperidinase (E.C. 3.2.1.40), was most active in the specific release of one glucose molecule from the disaccharide lipid. The novel glucolipid was isolated and characterized. The surface and interfacial tension of aqueous solutions were measured and compared with the lactonic and acidic sophorolipid.     

An agonist of the MscL channel affects multiple bacterial species and increases membrane permeability and potency of common antibiotics

The bacterial MscL channel normally functions as an emergency release valve discharging cytoplasmic solutes upon osmotic stress. The channel opens and passes molecules up to 30 Å and its pore is the largest of any gated channel. Opening the MscL pore inappropriately is detrimental to the bacterial cell, suggesting MscL as a potential novel drug target. A small‐molecule compound, 011A, has been shown to increase sensitivity of the Escherichia coli MscL channel, slow growth, and even decrease viability of quiescent cultures. The mscL gene is highly conserved and found in the vast majority of bacterial species, including pathogens. Here, we test the hypothesis that 011A can influence the growth and viability of other bacterial species, specifically Staphylococcus aureus and Mycobacterium smegmatis, in a MscL‐dependent manner. Furthermore, we demonstrate that the 011A compound can increase potency of other antibiotics, presumably by permeabilizing the membrane and allowing easier access of the antibiotic into the cytoplasm. Thus, MscL activators have potential as novel broad‐spectrum antibiotics or adjuvants that work with antibiotics to selectively allow passage across bacterial membranes.     

Banding isolated metaphase chromosomes by a sequential fluorescent G/Q technique

Summary G/Q-banding is a new, rapid, fluorescent technique for banding isolated chromosomes that incorporates characteristics of both G- and Q-banding. G-bands, while easily characterized, are often inconsistent when using isolated chromosomes, and Q-bands, while reliable, fade rapidly under UV exposure, making prolonged observation and photography difficult. G/Q-banding combines these techniques to sequentially utilize quinacrine staining over Giemsa banding to produce slow-fading fluorescent G/Q-bands. The background fluorescence in G/Q preparations fades quickly under continued UV exposure, while the chromosomes remain brightly banded and can be observed and photographed for at least five minutes. G/Q-banding was extended to whole cell chromosome spreads and produced results identical to those obtained with isolated chromosomes. Whole cell karyotypes indicate that G/Q-bands generally correspond to Q-bands. Advantages of G/Q-banding as a unique and universal technique over current double-staining procedures are discussed.     

Alginate-chitosan microspheres for the specific sorption of antibodies

Potentially hemocompatible alginate-chitiosan microparticles and microcapsules coated with a semipermeable membrane with incorporated glycoconjugates were synthesized. The membrane acts as a barrier, which keeps the incorporated glycoconjugate from going outside but permits antibodies to penetrate inside and specifically bind to antigens, high-molecular polysaccharide conjugates. The supports obtained are highly competitive in sorption capacity with Sepharose modified by the same oligosaccharides.     

Evaluation of SMID agar for identification of salmonella in naturally contaminated veterinary samples

Five hundred naturally contaminated samples were examined in a trial where SMID agar was compared with either Brilliant Green agar, Rambach agar or Xylose, Lysine, Desoxycholate agar. There were no significant differences in sensitivity but SMID agar detected slightly more salmonella isolates than BGA agar following RVS enrichment and slightly less following Selenite enrichment. There was, however, a marked reduction in the level of false-positives when SMID agar was used.