Fluid dynamics of anaerobic fermentation

In beer fermentation, yeast cells are kept in suspension, despite their higher density, by natural agitation created by ascending CO₂ bubbles. Yeast cells are unable to nucleate bubbles but instead release CO₂ in a soluble form in such a way that the medium tends to become supersaturated. A higher concentration of yeast cells and the presence of solid particles cause the formation of bubbles at the bottom of the fermenter and practically only there. The rising bubbles grow and accelerate by sweeping the CO₂ formed throughout the fermenter by the suspended yeast cells, thereby creating a fluid regime. A mathematical expression relating the bubble agitation power to the fermentation parameters was obtained and used to design more efficient fermenter shapes.     

WH2 and proline‐rich domains of WASP‐family proteins collaborate to accelerate actin filament elongation

WASP‐family proteins are known to promote assembly of branched actin networks by stimulating the filament‐nucleating activity of the Arp2/3 complex. Here, we show that WASP‐family proteins also function as polymerases that accelerate elongation of uncapped actin filaments. When clustered on a surface, WASP‐family proteins can drive branched actin networks to grow much faster than they could by direct incorporation of soluble monomers. This polymerase activity arises from the coordinated action of two regulatory sequences: (i) a WASP homology 2 (WH2) domain that binds actin, and (ii) a proline‐rich sequence that binds profilin–actin complexes. In the absence of profilin, WH2 domains are sufficient to accelerate filament elongation, but in the presence of profilin, proline‐rich sequences are required to support polymerase activity by (i) bringing polymerization‐competent actin monomers in proximity to growing filament ends, and (ii) promoting shuttling of actin monomers from profilin–actin complexes onto nearby WH2 domains. Unoccupied WH2 domains transiently associate with free filament ends, preventing their growth and dynamically tethering the branched actin network to the WASP‐family proteins that create it. Collaboration between WH2 and proline‐rich sequences thus strikes a balance between filament growth and tethering. Our work expands the number of critical roles that WASP‐family proteins play in the assembly of branched actin networks to at least three: (i) promoting dendritic nucleation; (ii) linking actin networks to membranes; and (iii) accelerating filament elongation.     

The antitumor effect of bleomycin combined with bestatin against Ehrlich ascites carcinoma in mice

The effect of bleomycin against Ehrlich ascites carcinoma transplanted subcutaneously to mice used in combination with bestatin was investigated. Male Balb/c mice weighting approximately 20 g and bred in our laboratories were used in this study. Each mouse was injected in its left lateral abdominal region subcutaneously with 7 X 10(6) tumor cells in 0.2 ml of ascites fluid. The mice were divided into four groups: control, bestatin alone (5 mg/kg intraperitoneally on Days 9-14), bleomycin alone (10 mg/kg intraperitoneally on Days 7 and 8), and bestatin plus bleomycin. Our results show that bestatin enhances the antitumor effect of bleomycin against Ehrlich ascites carcinoma as measured by the increased survival rates. Being an agent of very low toxicity, bestatin should be considered as a part of the chemoimmunotherapy protocol.     

Light and Electron Microscopic Examinations of Methane-Producing Biofilms from Anaerobic Fixed-Bed Reactors

Ultrastructural examinations were performed on biofilms from eight anaerobic fixed-bed reactors filled with various packing materials and operated on fresh swine waste. By using light, UV, scanning, and transmission electron microscopy, the distribution of a diverse microbial population composed of bacteria and a few yeasts was determined. This is the first time that the ultrastructure of in situ anaerobic digestor biofilms has been reported. A large number of methanogenic bacteria were identified by their fluorescence under 420 nm of radiation. Of these, two morphologically distinct types were most prevalent in the films. Methanothrix spp. was present in high numbers at the film surface, whereas Methanosarcina spp. were commonly embedded in the lower regions of the film. Inhabitants of the film were surrounded by an exopolysaccharide matrix that was very dense toward the base. An extensive network of channels was observed throughout the matrix that may facilitate gas and nutrient exchange to the lower regions of the film.     

Antidepressant drugs act by directly binding to TRKB neurotrophin receptors

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Size of Cell-Surface Kv2.1 Domains is Governed by Growth Fluctuations

The Kv2.1 voltage-gated potassium channel forms stable clusters on the surface of different mammalian cells. Even though these cell-surface structures have been observed for almost a decade, little is known about the mechanism by which cells maintain them. We measure the distribution of domain sizes to study the kinetics of their growth. Using a Fokker-Planck formalism, we find no evidence for a feedback mechanism present to maintain specific domain radii. Instead, the size of Kv2.1 clusters is consistent with a model where domain size is established by fluctuations in the trafficking machinery. These results are further validated using likelihood and Akaike weights to select the best model for the kinetics of domain growth consistent with our experimental data.     

No association between the SOCS-1 −1478CA/del polymorphism and ulcerative colitis in Turkish subjects

Suppressor of cytokine signaling (SOCS)-1 is an essential regulator of many cytokine signaling pathways, including those upregulated in the inflamed colonic mucosa of patients with ulcerative colitis. We sought to investigate whether the functional SOCS-1 ?1478CA>del polymorphism is associated with UC susceptibility and its disease phenotype in a Turkish clinical sample. A total of 104 subjects were enrolled in a case–control study (52 UC cases and 52 controls). The SOCS-1 ?1478CA>del polymorphism was genotyped using a polymerase chain reaction-restriction fragment length polymorphism (PCR–RFLP) method. The odds ratio of the del allele for UC relative to the CA allele was not significant (OR = 1.04, 95 % CI 0.59–1.82, P = 0.88). These results did not change after adjustment for age and sex in multivariable regression analysis (OR = 1.07, 95 % CI 0.42–1.69, P = 0.73). When the SOCS-1 ?1478CA>del polymorphism was analyzed among UC patients according to continuous disease and non-continuous disease, the del allele was not associated with disease recurrence (OR = 1.56, 95 % CI 0.78–4.56, P = 0.83). Furthermore, when we divided UC patients into two groups according to a previous history of colectomy, we found no significant effect of the del allele (OR = 1.94, 95 % CI 0.55–5.61, P = 0.91). Taken together, these findings suggest that SOCS-1 ?1478CA>del polymorphism does not contribute to UC susceptibility and its disease phenotype in Turkish subjects.