Improved method for regeneration and Agrobacterium-mediated transformation of Indian short-day onion (Allium cepa L.)

Plant Cell, Tissue and Organ Culture (PCTOC) - A high-auxin medium, usually used for callus induction, was not effective for Indian short-day onion cv. Bhima super. In this study, we found that the...     

VEGFR1 receptor tyrosine kinase localization to the Golgi apparatus is calcium-dependent

Vascular endothelial growth factor receptor 1 (VEGFR1) is an essential receptor tyrosine kinase that regulates mammalian vascular development and embryogenesis but its function is not well understood. Herein, we present evidence whereby endothelial VEGFR1 is largely resident within the Golgi apparatus but translocates to the plasma membrane via a calcium-regulated process. Primary human endothelial cells reveal differing VEGFR1 and VEGFR2 intracellular distribution and dynamics. The major proportion of the full-length VEGFR1 membrane protein was resident within the Golgi apparatus in primary endothelial cells. Whereas VEGFR2 displayed down-regulation in response to VEGF-A, VEGFR1 was not significantly affected arguing for a significant intracellular pool that was inaccessible to extracellular VEGF-A. This intracellular VEGFR1 pool showed significant co-distribution with key Golgi residents. Brefeldin A caused VEGFR1 Golgi fragmentation consistent with redistribution to the endoplasmic reticulum. Metabolic labeling experiments and microscopy using domain-specific VEGFR1 antibodies indicated that the mature processed VEGFR1 species and an integral membrane protein was resident within Golgi apparatus. Cytosolic calcium ions play a key role in VEGFR1 trafficking as treatment with either VEGF-A, histamine, thrombin, thapsigargin or A23187 ionophore caused VEGFR1 redistribution from the Golgi apparatus to small punctate vesicles and plasma membrane. We thus propose a model whereby the balance of VEGFR1 and VEGFR2 plasma membrane levels dictate either negative or positive endothelial signaling to influence vascular physiology.     

Nucleotide exchange and cGMP phosphodiesterase activation by pertussis toxin inactivated transducin.

Transducin, the signal coupling protein of retinal rod photoreceptor cells, is one of a family of G proteins that can be inactivated by pertussis toxin. We have investigated the nature of this inactivation in order to determine (1) whether it requires the toxin-catalyzed transfer of ADP-ribose from NAD+ to cysteine-347 of the alpha subunit and (2) whether it involves locking the alpha subunit in the inactive conformation characteristic of its GDP-bound state, or is limited to disruption of binding to photoexcited rhodopsin (R*). Our results indicate that all observed effects of pertussis toxin treatment, including a shift in the electrophoretic mobility of transducin's alpha subunit and functional inactivation, require NAD+ and that the appearance of the shift parallels incorporation of ADP-ribose. We have also found that, apart from interactions with photoexcited rhodopsin, the functional properties of ADP-ribosylated transducin are essentially the same as those of unmodified transducin. Normal spontaneous nucleotide exchange kinetics and the ability to activate cGMP phosphodiesterase are preserved following quantitative ADP-ribosylation, as are the abilities to hydrolyze GTP, to bind to a dye affinity column, and to display enhanced fluorescence upon addition of Al3+ and F-. Thus, ADP-ribosylation merely blocks catalysis of transducin nucleotide exchange by R* and does not lock transducin in an inactive state.(ABSTRACT TRUNCATED AT 250 WORDS)     

Microbial healing of cracks in concrete: a review

Concrete is the most widely used construction material of the world and maintaining concrete structures from premature deterioration is proving to be a great challenge. Early age formation of micro-cracking in concrete structure severely affects the serviceability leading to high cost of maintenance. Apart from conventional methods of repairing cracks with sealants or treating the concrete with adhesive chemicals to prevent the cracks from widening, a microbial crack-healing approach has shown promising results. The unique feature of the microbial system is that it enables self-healing of concrete. The effectiveness of microbially induced calcium carbonate precipitation (MICCP) in improving durability of cementitious building materials, restoration of stone monuments and soil bioclogging is discussed. Main emphasis has been laid on the potential of bacteria-based crack repair in concrete structure and the applications of different bacterial treatments to self-healing cracks. Furthermore, recommendations to employ the MICCP technology at commercial scale and reduction in the cost of application are provided in this review.     

Dynamics of water and ions around DNA: What is so special about them?

Water around biomolecules is special for behaving strangely – both in terms of structure and dynamics, while ions are found to control various interactions in biomolecules such as DNA, proteins and lipids. The questions that how water and ions around these biomolecules behave in terms of their structure and dynamics, and how they affect the biomolecular functions have triggered tremendous research activities worldwide. Such activities not only unfolded important static and dynamic properties of water and ions around these biomolecules, but also provoked heated debate regarding their explanation and role in biological functions. DNA, being negatively charged, interacts strongly with the surrounding dipolar water and positively charged counterions, leading to complex electrostatic coupling of water and ions with the DNA. Recent time-resolved fluorescence Stokes shift experiments and related computer simulation studies from our and other laboratories have unfolded some unique dynamic characteristics of water and ions near different structures of DNA. These results are discussed here to showcase the specialty of water and ion dynamics around DNA.     

Chemical modification of alpha-chymotrypsin for obtaining high transesterification activity in low water organic media

Alpha-chymotrypsin was made more hydrophilic by modifying 11 (out of 16) ε-amino groups with pyromellitic dianhydride. The hydrophilic preparation was precipitated with n-propanol. This preparation gave significantly higher initial rates at the optimum a_w (127.51 nmol mg^?1 min^?1 in n-octane and 21.30 nmol mg^?1 min^?1 in acetonitrile at a_w=0.33) compared with the lyophilized preparation (53.50 nmol mg^?1 min^?1 in n-octane and 0.26 nmol mg^?1 min^?1 in acetonitrile at a_w=0.97). FT-IR showed that the precipitate of modified alpha-chymotrypsin has a higher content of alpha-helices and beta-sheets compared to the lyophilized powder.