l-Ribulose production by an Escherichia coli harboring l-arabinose isomerase from Bacillus licheniformis

Recombinant Escherichia coli harboring the l-arabinose isomerase (BLAI) from Bacillus licheniformis was used as a biocatalyst to produce l-ribulose in the presence of borate. Effects of substrate concentration, the borate to l-arabinose ratio, pH, and temperature on the conversion of l-arabinose to l-ribulose were investigated. l-Ribulose production was efficient when pH was higher than 9 and temperature was higher than 50 °C. Borate addition to the reaction mixture was essential for high conversion of l-arabinose to l-ribulose as it resulted in an equilibrium shift in favor of the product. Under the optimal conditions determined by response surface methodology, the E. coli harboring BLAI produced 375 g l⁻¹ L-ribulose from 500 g l⁻¹ l-arabinose at a reaction time of 60 min, corresponding to a conversion yield of 75% and productivity of 375 g l⁻¹ h⁻¹. When the resting recombinant E. coli cells were recycled, 85% of the yield was obtained even after seven cycles of reuse. The productivity and final concentration of l-ribulose obtained in the present study were the highest yet reported.     

Role of sphingomyelin synthase in controlling the antimicrobial activity of neutrophils against Cryptococcus neoformans

The key host cellular pathway(s) necessary to control the infection caused by inhalation of the environmental fungal pathogen Cryptococcus neoformans are still largely unknown. Here we have identified that the sphingolipid pathway in neutrophils is required for them to exert their killing activity on the fungus. In particular, using both pharmacological and genetic approaches, we show that inhibition of sphingomyelin synthase (SMS) activity profoundly impairs the killing ability of neutrophils by preventing the extracellular release of an antifungal factor(s). We next found that inhibition of protein kinase D (PKD), which controls vesicular sorting and secretion and is regulated by diacylglycerol (DAG) produced by SMS, totally blocks the extracellular killing activity of neutrophils against C. neoformans. The expression of SMS genes, SMS activity and the levels of the lipids regulated by SMS (namely sphingomyelin (SM) and DAG) are up-regulated during neutrophil differentiation. Finally, tissue imaging of lungs infected with C. neoformans using matrix-assisted laser desorption-ionization mass spectrometry (MALDI-MS), revealed that specific SM species are associated with neutrophil infiltration at the site of the infection. This study establishes a key role for SMS in the regulation of the killing activity of neutrophils against C. neoformans through a DAG-PKD dependent mechanism, and provides, for the first time, new insights into the protective role of host sphingolipids against a fungal infection.     

Purification and Characterization of Trochus radiatus Derived Low Molecular Weight Bactericidal Polypeptide Active Against ESKAPE Pathogens

International Journal of Peptide Research and Therapeutics - Antimicrobial peptides comprise core components of innate defense and act as first-line defense molecules in most marine mollusks....     

In situ feeding tactics of short-nosed fruit bat (Cynopterus sphinx) on mango fruits: evidence of extractive foraging in a flying mammal

We report a sequence of behaviors exhibited by the short-nosed fruit bat Cynopterus sphinx while feeding on fruits of Mangifera indica. They peel off the outer skin to form a feeding area of about 3–6 cm diameter. Such food preparatory behaviors were more pronounced on larger mangoes. Bats competed among themselves to feed on the mangoes that had such feeding areas exposed. Individuals that spent a considerable amount of time on food preparatory behaviors actively secured the fruits. Altogether, these behaviors indicate that Cynopterus bats might have learnt, over evolutionary time, and developed behaviors that facilitate efficient processing and feeding of fruits such as mangoes. It appears that actions exhibited by C. sphinx in peeling off the outer skin of mangoes exemplify “extractive foraging”, a behavior that is prominently known in large-brained mammals. Thus, our findings will have implications on the distribution and evolution of extractive foraging and “technical intelligence” among mammalian lineages.     

Role of large hydrophobic residues in proteins

Large Hydrophobic Residues (LHR) such as phenylalanine, isoleucine, leucine, methionine and valine play an important role in protein structure and activity. We describe the role of LHR in complete set of protein sequences in 15 different species. That is the distribution of LHR in different proteins of different species is reported. It is observed that the proteins prefer to have 27% of large hydrophobic residues in total and all along the sequence. It is also observed that proteins accumulate more LHR in its active sites. A window analysis on these protein sequences shows that the 27% of LHR is more frequent at window length of 45 amino acids. The influenza virus and P. falciparum show a random distribution of LHR in its proteins compared to other model organisms.     

Laticiferous taxa as a source of energy and hydrocarbon

Twenty-nine laticiferous taxa of Apocynaceae, Asclepiadaceae, and Sapotaceae were screened for suitability as alternative sources of renewable energy, rubber, and phytochemicals and to select the most promising ones for large-scale cultivation. Of these,Allamanda violacea (14.9% protein, 13.8% polyphenol, 8.6% oil, 3.2% hydrocarbon),Catharanthus roseus (15.4% protein, 10.4% polyphenol, 11.5% oil, 1.9% hydrocarbon), andHolarrhena antidysenterica (14.2% protein, 16.4% polyphenol, 5.4% oil, 4.8% hydrocarbon) of Apocynaceae;Asclepias curassavica (19.3% protein, 6.5% polyphenol, 3.9% oil, 2.0% hydrocarbon), Calotropis gigantea (18.5% protein, 6.8% polyphenol, 7.0% oil, 2.8% hydrocarbon) of Asclepiadaceae;Mimusops elengi (11.3% protein, 9.7% polyphenol, 7.2% oil, 4.0% hydrocarbon) of Sapotaceae show promising potential for future petrochemical plantations; of all these taxa,Holarrhena antidysenterica yielded an unusually high percentage (4.8%) of hydrocarbon fraction followed byMimusops elengi (4.0%). NMR spectra confirmed the presence of cis-polyisoprene in all species studied exceptNerium indicum (white-flowered var.). These data indicate that the majority of the species under investigation may be considered for large-scale cultivation as an alternative source of rubber, intermediate energy, and other phytochemicals.