17 β-Estradiol Enhances the Outgrowth and Survival of Neocortical Neurons in Culture

Results of this investigation demonstrate that exposure to 17 -estradiol differentially and significantly regulates cortical nerve cell outgrowth depending on the cortical region. Parietal and occipital neurons treated with 1 nM 17 -estradiol showed a greater magnitude of neuronal outgrowth whereas outgrowth of temporal cortex neurons was decreased in the presence of 1 nM 17 -estradiol. Frontal cortex neurons showed a consistent enhancement of neuronal outgrowth that did not reach statistical significance. The dose response profile for 17 -estradiol regulation of the macromorphological features exhibited a bimodal dose response relationship whereas the dose response profile for 17 -estradiol regulation of the micromorphological features exhibited a dose response more characteristic of an inverted V-shaped function. An antagonist to the NMDA receptor antagonist, AP5, abolished the growth promoting effect of 17 -estradiol whereas the nuclear estrogen receptor antagonist ICI 182,780 did not. Lastly, neocortical neurons exposed to 17 -estradiol exhibited greater viability and survival than control neurons over a two week period. These data indicate that 17 -estradiol can enhance the growth and viability of select populations of neocortical neurons and that the growth promoting effects of 17 -estradiol can be blocked by an antagonist to the NMDA glutamate receptor and not by an antagonist to the estrogen nuclear receptor.     

A 5.5-Mb High-Resolution Integrated Map of Distal 11q13

The distal part of 11q13, which contains several genes relevant to human diseases, has been poorly mapped as part of genome-wide mapping efforts. In the prospect of drawing a fine-scale integrated map of the area containingKRN1andOMP,we have established a framework of markers by hybridization to DNA of somatic cell hybrids and by fluorescencein situhybridization (FISH) on metaphase chromosomes. The probes studied were used to isolate 27 YACs and 16 cosmids that could be organized in three contigs covering approximately 6 Mb. These contigs were separated by two gaps that are likely to contain sequences underrepresented in YAC libraries. They were then integrated based on long-range restriction mapping and DNA-fiber FISH into a high-resolution physical map, which covers a 5.5-Mb region and includes 36 anonymous markers and 10 genes. This map will be used to search for genes within the 2/3 of this region where none have been localized as yet. It will also lay the ground for the characterization of an amplicon surroundingGARPin breast cancer and for the search of disease genes within this region.     

New sialic acids from biological sources identified by a comprehensive and sensitive approach: liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) of SIA quinoxalinones

Sialic acids are a family of 9-carbon carboxylated sugars, wheredifferent substitutions of the backbone define over 30 members.Biological roles of these substitutions have been missed untilrecently because of their low abundance and lability to conventionalisolation/purification methods. This new approach characterizessialic acids using electrospray ionization-mass spectrometry(ESI-MS) to monitor the HPLC separation of their DMB (1,2-diamino-4,5-methylenedioxy-benzene)derivatives (quinoxalinones). A combination of retention timesand spectra characteristics allows definition of the type andposition of the various substituents. This approach requiresno previous purification, involving a simple derivatizationreaction followed by direct injection on the microbore HPLCcolumn. A complete spectrum, including molecular ions and CADfragments of a sialic acid qainoxalinone, is obtained by injecting10–20 pmol of the compound. Individual quinoxalinonescan be purified by regular RP-HPLC and analyzed by direct-injectionESI-MS or LSIMS. Using this approach, we identified 28 differentsialic acids, including the following new species: Neu5Gc9Lt(BSM), anhydro derivatives of Neu5Ac other than the 4,8-anhydro(horse serum hydrolyzates), KDNS(7)Ac and KDN5(7),9Ac₂ (amphibianPleurodeles waltl), four isomers of Neu5Gc8MexAc and three anhydroderivatives of Neu5Gc8MS (glycolipids of the starfish Pisasterbrevirpinus), and Neu5Ac8S (in addition to Neu5Gc8S, in theglycolipids of the sea urchin Lovenia cordiformis). Resultsshow the usefulness of LC-ESIMS to study sialic acid diversity,and identification of small amounts of unexpected sialic acidsor new members of their family. sialic acid purification electrospray ionizationmass spectrometry quinoxalinone     

STEM ELONGATION OF XANTHIUM PLANTS PRESENTED IN TERMS OF RELATIVE ELEMENTAL RATES

Vegetative Xanthium plants grown under noninductive conditions were marked along the stem with India ink and photographed during three successive days. The relative elemental rates of stem elongation [d(dX/dt)/dX] were estimated for 18 plants between 15 and 18 plastochrons. On the average, only the 8.0 cm terminal part of the stem was elongating in this group of plants. Young internodes were elongating at constant relative elemental rates ([d(dX/dt)/dX] was about 0.2 days^–1); nodal portions of the stem beteween two young internodes were not elongating. Internodes longer than 2 cm displayed an acropetal pattern of elongation in which the basal part of an internode stopped elongating and matured first and the apical portion last. The pattern of elongation of the stem could be best approximated to a set of cascading waterfalls with declining plateaus in the direction of the water flow. The acropetal pattern of individual internode elongation observed in Xanthium was similar to those reported for Helianthus and Phaseolus internode growth.     

Kinetic studies of the enzymatic isomerization of xylose

d-Xylose isomerase catalyses the conversion of the common pentose, d-xylose, to its keto-isomer, d-xylose. This reaction is of interest because many microorganisms that are unable to metabolize d-xylose can utilize d-xylulose. The kinetics of a commonly used immobilized whole-cell isomerase, Sweetzyme Q, have been determined from initial rate studies on the forward and reverse reactions. The effect of pH, temperature, and substrate and product concentration on enzyme activity have all been examined. Reaction rates were modelled with the Michaelis-Menten equation. Using constants determined from Lineweaver-Burk plots, the rate equation accurately simulated experimental conversion data.     

Strategies to reduce end‐product inhibition in family 48 glycoside hydrolases

Family 48 cellobiohydrolases are some of the most abundant glycoside hydrolases in nature. They are able to degrade cellulosic biomass and therefore serve as good enzyme candidates for biofuel production. Family 48 cellulases hydrolyze cellulose chains via a processive mechanism, and produce end products composed primarily of cellobiose as well as other cellooligomers (dp ≤ 4). The challenge of utilizing cellulases in biofuel production lies in their extremely slow turnover rate. A factor contributing to the low enzyme activity is suggested to be product binding to enzyme and the resulting performance inhibition. In this study, we quantitatively evaluated the product inhibitory effect of four family 48 glycoside hydrolases using molecular dynamics simulations and product expulsion free‐energy calculations. We also suggested a series of single mutants of the four family 48 glycoside hydrolases with theoretically reduced level of product inhibition. The theoretical calculations provide a guide for future experimental studies designed to produce mutant cellulases with enhanced activity. Proteins 2016; 84:295–304. © 2016 Wiley Periodicals, Inc.