Solid-state fermentation of sugarcane bagasse with Flammulina velutipes and Trametes versicolor

The mushroom Flammulina velutipes and the white-rot fungus Trametes versicolor were cultivated separately on sugarcane bagasse for 40 days. Trametes versicolor produced laccase and manganese-peroxidase activities, showing a simultaneous degradation of lignin and holocellulose. However, only phenoloxidase activity was found with Flammulina velutipes. A preferential degradation of lignin was detected in F. velutipes, which exhibited a greater reduction in the ratio of weight loss to lignin loss than T. versicolor. A decrease in the syringyl/guaiacyl ratio observed with both fungi indicated the preferential degradation of non-condensed (syringyl-type) lignin units. An increase in the relative abundance of aromatic carboxylic acids suggested that the oxidative transformation of lignin unit side-chains was occurring. This was more noticeable with Flammulina velutipes than with T. versicolor.     

Salicylic acid induced physiological and biochemical changes in wheat seedlings under water stress

Salicylic acid (SA) is an important signal molecule modulating plantresponses to stress. It is recently reported to induce multiple stresstolerancein plants including drought. An experiment was, therefore, conducted toascertain the effect of salicylic acid on the growth and metabolic profile ofwheat seedlings under water stress. Irrespective of the SA concentration(1–3 mM) and water stress, SA treated plants showed, ingeneral, a higher moisture content, dry mass, carboxylase activity of Rubisco,superoxide dismutase (SOD) activity and total chlorophyll compared to those ofuntreated seedlings. SA treatment, under water stress, protected nitratereductase (NR) activity and maintained, especially at 3 mM SAconcentration, the protein and nitrogen content of leaves compared to watersufficient seedlings. Results signify the role of SA in regulating the droughtresponse of plants and suggest that SA could be used as a potential growthregulator, for improving plant growth under water stress.     

Heme geometry in the 10 K photoproduct from sperm whale carbonmonoxymyoglobin

We have measured the Soret band of the photoproduct obtained by complete photolysis of sperm whale carbonmonoxymyoglobin at 10 K. The experimental spectrum has been modeled with an analytical expression that takes into account the homogeneous bandwidth, the coupling of the electronic transition with both high and low frequency vibrational modes, and the effects of static conformational heterogeneity. The comparison with deoxymyoglobin at low temperature reveals three main differences. In the photoproduct, the Soret band is shifted to red. The band is less asymmetric, and an enhanced coupling to the heme vibrational mode at 674 cm⁻¹ is observed. These differences reflect incomplete relaxation of the active site after ligand dissociation. The smaller band asymmetry of the photoproduct can be explained by a smaller displacement of the iron atom from the mean porphyrin plane, in quantitative agreement with the X-ray structure analysis. The enhanced vibrational coupling is attributed to a subtle heme distortion from the planar geometry that is barely detectable in the X-ray structure.     

Optimizing recombinant protein expression in the T7 system under the control of the proUp promoter

-Galactosidase and streptokinase expression was tested under the control of the T7 promoter in batch and fed-batch cultures. An Escherichia coli host GJ1158, which contained the T7 RNA polymerase gene under the osmo-responsive proUp promoter, was used for expression studies. -Galactosidase expression was enhanced from 26 mg l^–1 to 127 mg l^–1 in batch culture when a combination of sucrose and sorbitol was used instead of salt as an inducer. Similarly in fed-batch cultures 140 mg streptokinase l^–1 was formed with sucrose and sorbitol induction which was higher than that achieved with IPTG induced cultures.     

Response surface methodology for lovastatin production by Aspergillus terreus GD13 strain

A wild type Aspergillus terreus GD13 strain, chosen after extensive screening, was optimized for lovastatin production using statistical Box-Behnken design of experiments. The interactive effect of four process parameters, i.e. lactose and soybean meal, inoculum size (spore concentration) and age of the spore culture, on the production of lovastatin was evaluated employing response surface methodology (RSM). The model highlighted the positive effect of soybean meal concentration and inoculum level for achieving maximal level of lovastatin (1342 mg/l). The optimal fermentation conditions improved the lovastatin titre by 7.0-folds when compared to the titres obtained under unoptimized conditions.     

Notch ligand endocytosis generates mechanical pulling force dependent on dynamin, epsins, and actin

Notch signaling induced by cell surface ligands is critical to development and maintenance of many eukaryotic organisms. Notch and its ligands are integral membrane proteins that facilitate direct cell-cell interactions to activate Notch proteolysis and release the intracellular domain that directs Notch-specific cellular responses. Genetic studies suggest that Notch ligands require endocytosis, ubiquitylation, and epsin endocytic adaptors to activate signaling, but the exact role of ligand endocytosis remains unresolved. Here we characterize a molecularly distinct mode of clathrin-mediated endocytosis requiring ligand ubiquitylation, epsins, and actin for ligand cells to activate signaling in Notch cells. Using a cell-bead optical tweezers system, we obtained evidence for cell-mediated mechanical force dependent on this distinct mode of ligand endocytosis. We propose that the mechanical pulling force produced by endocytosis of Notch-bound ligand drives conformational changes in Notch that permit activating proteolysis.     

Complete nucleotide sequence of polyomavirus SA12

The Polyomaviridae have small icosahedral virions that contain a genome of approximately 5,000 bp of circular double-stranded DNA. Polyomaviruses infect hosts ranging from humans to birds, and some members of this family induce tumors in test animals or in their natural hosts. We report the complete nucleotide sequence of simian agent 12 (SA12), whose natural host is thought to be Papio ursinus, the chacma baboon. The 5,230-bp genome has a genetic organization typical of polyomaviruses. Sequences encoding large T antigen, small t antigen, agnoprotein, and the viral capsid proteins VP1, VP2, and VP3 are present in the expected locations. We show that, like its close relative simian virus 40 (SV40), SA12 expresses microRNAs that are encoded by the late DNA strand overlapping the 3' end of large T antigen coding sequences. Based on sequence comparisons, SA12 is most closely related to BK virus (BKV), a human polyomavirus. We have developed a real-time PCR test that distinguishes SA12 from BKV and the other closely related polyomaviruses JC virus and SV40. The close relationship between SA12 and BKV raises the possibility that these viruses circulate between human and baboon hosts.