Discovery of novel,orally available benzimidazoles as melanin concentrating hormone receptor 1 (MCHR1) antagonists

Melanin concentrating hormone (MCH) is an important mediator of energy homeostasis and plays role in several disorders such as obesity, stress, depression and anxiety. The synthesis and biological evaluation of novel benzimidazole derivatives as MCHR1 antagonists are described. The in vivo proof of principle for weight loss with a lead compound from this series is exemplified.     

Interaction of Zinc, Ascorbic Acid, and Folic Acid in Glycation with Albumin as Protein Model

Using albumin as model, we conducted series of in vitro glycation experiments to examine role of zinc in glycation using glucose at 4–100 mg/ml, incubations at 37°C or 60°C, duration of 2 or 4 weeks and in presence of zinc or ascorbic acid (AA) or folic acid (FA). Modifications of bovine serum albumin (BSA) were examined by using fluorescence of advanced glycation end products (AGEs) and dityrosine, UV, and Fourier transformed infrared spectroscopy. Adding zinc (0 to 768.5 μmol/l) resulted in significant inhibition of albumin glycation by glucose with a linear fit, $ y = - 0.0{895}x + {23}0.{99}\left( {{R^2} = 0.{7676},p = 0.0{13}} \right) $ . The glycation by fructose was greater than that of glucose with stronger inhibitory effect by zinc in fructose–glycation (t?=??5.8, p?=?0.002). Addition of zinc significantly decreased fluorescence as seen in Zn?+?FA or Zn?+?AA sets as compared to sets of FA alone (p?=?0.00056) or AA alone (p?=?0.037). The fluorescence for dityrosine and AGE had a correlation of 0.897 (p?<?0.01). The data from fluorescence, UV, and FTIR spectra collectively suggested inhibitory effect of zinc in BSA glycation alone or in presence of FA and AA, showing new dimension for the protective action of zinc in hyperglycemic conditions.     

What does it take to be a plant pathogen: genomic insights from <Emphasis Type="Italic">Streptomyces</Emphasis> species

Plant pathogenicity is rare in the genus Streptomyces, with only a dozen or so species possessing this trait out of the more than 900 species described. Nevertheless, such species have had a significant impact on agricultural economies throughout the world due to their ability to cause important crop diseases such as potato common scab, which is characterized by lesions that form on the potato tuber surface. All pathogenic species that cause common scab produce a family of phytotoxins called the thaxtomins, which function as cellulose synthesis inhibitors. In addition, the nec1 and tomA genes are conserved in several pathogenic streptomycetes, the former of which is predicted to function in the suppression of plant defense responses. Streptomyces scabies is the oldest plant pathogen described and has a world-wide distribution, whereas species such as S. turgidiscabies and S. acidiscabies are believed to be newly emergent pathogens found in more limited geographical locations. The genome sequence of S. scabies 87-22 was recently completed, and comparative genomic analyses with other sequenced microbial pathogens have revealed the presence of additional genes that may play a role in plant pathogenicity, an idea that is supported by functional analysis of one such putative virulence locus. In addition, the availability of multiple genome sequences for both pathogenic and nonpathogenic streptomycetes has provided an opportunity for comparative genomic analyses to identify the Streptomyces pathogenome. Such genomic analyses will contribute to the fundamental understanding of the mechanisms and evolution of plant pathogenicity and plant-microbe biology within this genus.     

Direct and callus-mediated protocorm-like body induction from shoot-tips of <Emphasis Type="Italic">Dendrobium chrysotoxum</Emphasis> Lindl. (Orchidaceae)

An efficient method of mass propagation of Dendrobium chrysotoxum Lindl. was developed using a shoot-tip culture system. Both direct and callus-mediated formation of protocorm-like bodies (PLBs) occurred from the basal cut surface of explants. Frequency of callusing was best in the presence of 2 μM thidiazuron (TDZ) or N⁶-benzylaminopurine (BAP). The callus exhibited complete hormone autonomy for growth and differentiation of PLBs and was maintained for 18 months without any exogenous growth regulators, an aspect important for minimising somaclonal variation. However, the rate of callus growth and PLB formation varied with application of cytokinin and auxin. In addition, the callus exhibited a differential sensitivity to the exogenous cytokinins. While BAP promoted callus growth and PLB differentiation, TDZ was inhibitory to callus mediated PLB formation and caused extensive necrosis of callus. Although α-naphthaleneacetic acid (NAA) had no significant effect on the induction of callus, subsequent growth was best in its presence. Using a 3-month subculture period, a 69-fold increase in callus weight was achieved with 0.5 μM NAA, while as many as 133 PLBs could be obtained per 100 mg callus in the presence of 1 μM NAA. For direct PLB formation, the optimum cytokinin dosage was dependent upon the type of cytokinin used. While TDZ was most effective at a concentration of 1 μM (15 PLBs per explant), for similar PLB yield the application of 8 μM BAP was essential.     

Posttranslational regulation of I-Ed by affinity for CLIP

Several MHC class II alleles linked with autoimmune diseases form unusually low stability complexes with CLIP, leading us to hypothesize that this is an important feature contributing to autoimmune pathogenesis. To investigate cellular consequences of altering class II/CLIP affinity, we evaluated invariant chain (Ii) mutants with varying CLIP affinity for a mouse class II allele, I-E(d), which has low affinity for wild-type CLIP and is associated with a mouse model of spontaneous, autoimmune joint inflammation. Increasing CLIP affinity for I-E(d) resulted in increased cell surface and total cellular abundance and half-life of I-E(d). This reveals a post-endoplasmic reticulum chaperoning capacity of Ii via its CLIP peptides. Quantitative effects on I-E(d) were less pronounced in DM-expressing cells, suggesting complementary chaperoning effects mediated by Ii and DM, and implying that the impact of allelic variation in CLIP affinity on immune responses will be highest in cells with limited DM activity. Differences in the ability of cell lines expressing wild-type or high-CLIP-affinity mutant Ii to present Ag to T cells suggest a model in which increased CLIP affinity for class II serves to restrict peptide loading to DM-containing compartments, ensuring proper editing of antigenic peptides.     

E(z), a depth-dependent potential for assessing the energies of insertion of amino acid side-chains into membranes: derivation and applications to determining the orientation of transmembrane and interfacial helices

We have developed an empirical residue-based potential (E(z) potential) for protein insertion in lipid membranes. Propensities for occurrence as a function of depth in the bilayer were calculated for the individual amino acid types from their distribution in known structures of helical membrane proteins. The propensities were then fit to continuous curves and converted to a potential using a reverse-Boltzman relationship. The E(z) potential demonstrated a good correlation with experimental data such as amino acid transfer free energy scales (water to membrane center and water to interface), and it incorporates transmembrane helices of varying composition in the membrane with trends similar to those obtained with translocon-mediated insertion experiments. The potential has a variety of applications in the analysis of natural membrane proteins as well as in the design of new ones. It can help in calculating the propensity of single helices to insert in the bilayer and estimate their tilt angle with respect to the bilayer normal. It can be utilized to discriminate amphiphilic helices that assume a parallel orientation at the membrane interface, such as those of membrane-active peptides. In membrane protein design applications, the potential allows an environment-dependent selection of amino acid identities.     

The Himalayas as a directional barrier to gene flow

High-resolution Y-chromosome haplogroup analyses coupled with Y-short tandem repeat (STR) haplotypes were used to (1) investigate the genetic affinities of three populations from Nepal--including Newar, Tamang, and people from cosmopolitan Kathmandu (referred to as "Kathmandu" subsequently)--as well as a collection from Tibet and (2) evaluate whether the Himalayan mountain range represents a geographic barrier for gene flow between the Tibetan plateau and the South Asian subcontinent. The results suggest that the Tibetans and Nepalese are in part descendants of Tibeto-Burman-speaking groups originating from Northeast Asia. All four populations are represented predominantly by haplogroup O3a5-M134-derived chromosomes, whose Y-STR-based age (+/-SE) was estimated at 8.1+/-2.9 thousand years ago (KYA), more recent than its Southeast Asian counterpart. The most pronounced difference between the two regions is reflected in the opposing high-frequency distributions of haplogroups D in Tibet and R in Nepal. With the exception of Tamang, both Newar and Kathmandu exhibit considerable similarities to the Indian Y-haplogroup distribution, particularly in their haplogroup R and H composition. These results indicate gene flow from the Indian subcontinent and, in the case of haplogroup R, from Eurasia as well, a conclusion that is also supported by the admixture analysis. In contrast, whereas haplogroup D is completely absent in Nepal, it accounts for 50.6% of the Tibetan Y-chromosome gene pool. Coalescent analyses suggest that the expansion of haplogroup D derivatives--namely, D1-M15 and D3-P47 in Tibet--involved two different demographic events (5.1+/-1.8 and 11.3+/-3.7 KYA, respectively) that are more recent than those of D2-M55 representatives common in Japan. Low frequencies, relative to Nepal, of haplogroup J and R lineages in Tibet are also consistent with restricted gene flow from the subcontinent. Yet the presence of haplogroup O3a5-M134 representatives in Nepal indicates that the Himalayas have been permeable to dispersals from the east. These genetic patterns suggest that this cordillera has been a biased bidirectional barrier.