Heteroglucan-dendrimer glycoconjugate: a modulated construct with augmented immune responses and signaling phenomena

Background

Newer strategies for augmenting immune responses of pharmacologically active glucans may serve to improve the medicinal potential of these biomolecules. With this aim, the present work was focused on generating targeted high molecular size glucan particles with magnified immune response activity.

Methods

Heteroglucans were conjugated with PAMAM dendrimers using a Schiff base reductive amination reaction to generate a polytethered molecule with multiple glucan motifs. The modulated construct was characterized by FTIR, TEM, ¹H NMR and dynamic light scattering (DLS) methods. Effects of conjugated glucans were examined in RAW 264.7 macrophage cells as well as in S-180 murine tumor models.

Results

Dendrimer-conjugated glucans were found to exhibit a two-fold increase in immune stimulation in comparison to unconjugated glucans. This may be corroborated by the predominant enhancement in immunological functions such as nitric oxide production, ROS generation and immune directed tumor inhibition in murine models. Immune cell surface markers (CD4, CD8, CD19, MHC-II) and cytokine levels were also found to be highly up-regulated in the splenocytes of mice subjected to particulate glucan administration. Our study also demonstrated that conjugated glucan treatment to RAW 264.7 cells strongly enhanced the phosphorylation of two downstream signalling molecules of the mitogen activated protein kinase (MAPKs) family: p38 and MEK1/2 relative to single glucans thereby relating molecular mechanisms with enhanced immune stimulation.

Conclusions and general significance

The results obtained thus support that particulate format of soluble heteroglucan will thereby improve its functionality and identify leads in therapeutic competence.     

Substitution of Alanine at Position 184 with Glutamic Acid in <Emphasis Type="Italic">Escherichia coli</Emphasis> PBP5 Ω-Like Loop Introduces a Moderate Cephalosporinase Activity

Escherichia coli PBP5, a DD-carboxypeptidase (DD-CPase), helps in maintaining cell shape and intrinsic β-lactam resistance. Though PBP5 does not have β-lactamase activity under physiological pH, it has a common but shorter Ω-like loop resembling class A β-lactamases. However, such Ω-like loop lacks the key glutamic acid residue that is present in β-lactamases. It is speculated that β-lactamases and DD-CPases might have undergone divergent evolution leading to distinct enzymes with different substrate specificities and functions indicating the versatility of the Ω-loops. Nonetheless, direct experimental evidence favoring the idea is insufficient. Here, aiming to investigate the effect of introducing a glutamic acid residue in the PBP5 Ω-like loop, we substituted A184 to E to create PBP5_A184E. Expression of PBP5_A184E in E. coli ?PBP5 mutant elevates the β-lactam resistance, especially for cephalosporins. However, like PBP5, PBP5_A184E has the ability to complement the aberrantly shaped E. coli septuple PBP mutant indicating an unaffected in vivo DD-CPase activity. Biochemical and bioinformatics analyses have substantiated the dual enzyme nature of the mutated enzyme possessing both DD-CPase and β-lactamase activities. Therefore, substitution of A184 to E of Ω-like loop alone can introduce the cephalosporinase activity in E. coli PBP5 supporting the phenomenon of a single amino acid polymorphism.     

Karyotype diversity and interspecific 4C DNA variation inBupleurum

Investigation on karyotype, 4C nuclear DNA amount and interphase nuclear volume (INV) of different HimalayanBupleurum species belonging toUmbelliferae revealed genetic differentiation. Numerical and structural alternation of chromosomes in interspecific level were manifested in their statistically significant altered species specific 4C nuclear DNA content. Somatic chromosome number ranged between 2n = 14 and 2n = 16.B. himalayense was reported for the first time having 2n = 16 chromosomes. Correlation coefficient among the various chromosomal and nuclear parameters showed no significant progressive or regressive interdependence except in between INV and nuclear DNA amount. Critical differences between 4C DNA content showed interspecific variation.     

Detection and identification of phytoplasma associated with witches’ broom and little leaf disease in Arundo donax: first report from India

During the survey of two successive years 2012–2013, in nearby places of Gorakhpur districts, Uttar Pradesh, India, Arundo donax plants were found to be exhibiting witches’ broom, excessive branching accompanied with little leaf symptoms with considerable disease incidence. Nested PCR carried out with universal primers pair R16F2n/R16R2 employing the PCR (P1/P7) product as a template DNA (1:20) resulted in expected size positive amplification ~1.2 kb in all symptom-bearing plants suggested the association of phytoplasma with witches’ broom disease of Narkat plants. BLASTn analysis of the 16S rRNA gene sequence showed the highest (99%) sequence identity with Candidatus phytoplasma asteris (16SrI group). In phylogenetic analysis, the sequence data showed close relationships with the members of 16SrI phytoplasma and clustered within a single clade of 16SrI group and closed to B subgroup representatives. This is a first report of 16Sr I-B group phytoplasma associated with witches’ broom accompanied with little leaf disease of Narkat in India.     

Insulin adsorption onto zinc oxide nanoparticle mediates conformational rearrangement into amyloid-prone structure with enhanced cytotoxic propensity

Background

Injection localized amyloidosis is one of the most prevalent disorders in type II diabetes mellitus (TIIDM) patients relying on insulin injections. Previous studies have reported that nanoparticles can play a role in the amyloidogenic process of proteins. Hence, the present study deals with the effect of zinc oxide nanoparticles (ZnONP) on the amyloidogenicity and cytotoxicity of insulin.

Sister-chromatid exchanges induced by triethylenemelamine: in vivo and in vivo/in vitro studies in mouse and Chinese hamster bone marrow and spleen cells

This study was designed to obtain sister-chromatid exchange (SCE) frequencies in bone marrow and spleen cells of mice and Chinese hamsters under in vivo and in vivo/in vitro systems following treatment of animals with varying doses (15-405 micrograms/kg) of triethylenemelamine (TEM). A dose-related SCE response was found in both species, tissues, and systems analyzed following TEM treatment. In vivo, similar responses were noted for both tissues in both species. However, in vivo/in vitro, the response was lower than in vivo and it varied with the tissue. The spleen cells were more sensitive and gave higher numbers of SCEs than bone marrow of both species at the two highest doses tested (135 and 405 micrograms/kg). These differences may be attributed to cell-culturing effects, type of cells analyzed, species and tissue specificities, and pharmacokinetic properties of the chemical. This study lends support to recently established in vivo/in vitro cell culture methodologies employing mice and Chinese hamsters for comparative cytogenetic analysis.     

Possible mitochondrial involvement in mechanism of cytoplasmic male sterility in maize (Zea mays L.)

The mechanism of cytoplasmic male sterility was investigated in maize by isolating mitochondria from seedlings and various anther stages and analyzing cytochrome oxidase and succinic dehydrogenase biochemically and electrophoretically. Sterile anthers exhibited a lack of biochemical activity and fewer isozymatic bands for cytochrome oxidase. No apparent differences were detected biochemically or electrophoretically between fertile and sterile anthers for succinate dehydrogenase.     

查谟-克什米尔地区查谟后西瓦立克沉积中的亚洲象化石(英文)

描述了一件象属( Elephas) 的右上臼齿化石。标本产自查谟紧靠上西瓦立克亚群巨砾岩组( Boulder Conglomerate Formation) 之上的砂质、粉砂质泥岩夹砾石层中,化石地点位于查谟市南10 km,Kharian 村北约500 m 处。根据齿板数、齿脊频率、釉质层厚度、冠高指数、绝对大小和齿长/齿高指数等牙齿形态参数,暂时将之归为 Elephas cf. E. maximus indicus。还简短讨论了象属的地理分布和地质时代。     

The Light Skin Allele of SLC24A5 in South Asians and Europeans Shares Identity by Descent

Skin pigmentation is one of the most variable phenotypic traits in humans. A non-synonymous substitution (rs1426654) in the third exon of SLC24A5 accounts for lighter skin in Europeans but not in East Asians. A previous genome-wide association study carried out in a heterogeneous sample of UK immigrants of South Asian descent suggested that this gene also contributes significantly to skin pigmentation variation among South Asians. In the present study, we have quantitatively assessed skin pigmentation for a largely homogeneous cohort of 1228 individuals from the Southern region of the Indian subcontinent. Our data confirm significant association of rs1426654 SNP with skin pigmentation, explaining about 27% of total phenotypic variation in the cohort studied. Our extensive survey of the polymorphism in 1573 individuals from 54 ethnic populations across the Indian subcontinent reveals wide presence of the derived-A allele, although the frequencies vary substantially among populations. We also show that the geospatial pattern of this allele is complex, but most importantly, reflects strong influence of language, geography and demographic history of the populations. Sequencing 11.74 kb of SLC24A5 in 95 individuals worldwide reveals that the rs1426654-A alleles in South Asian and West Eurasian populations are monophyletic and occur on the background of a common haplotype that is characterized by low genetic diversity. We date the coalescence of the light skin associated allele at 22–28 KYA. Both our sequence and genome-wide genotype data confirm that this gene has been a target for positive selection among Europeans. However, the latter also shows additional evidence of selection in populations of the Middle East, Central Asia, Pakistan and North India but not in South India.     

In vivo effects of cadmium on calmodulin and calmodulin regulated enzymes in rat brain.

Effect of chronic cadmium (Cd) exposure and the influence of diethyldithiocarbamate (DDC) on Cd absorption was studied on the brain of young male Wistar rats. A significant amount of Cd accumulated in cerebral cortices of rats after 4 weeks of Cd (6 mg/kg body wt) exposure (through gastric intubation). The biological activity of calmodulin (CaM) decreased significantly (p less than 0.001) in the cerebral cortices of these animals in comparison to the control group. 3'-5' Phosphodiesterase and synaptic membrane Ca(2+)-Mg(2+) ATPase were also significantly affected (p less than 0.01 and p less than 0.001 respectively). However, Cd treatment did not alter synaptic membrane adenylate cyclase activity and DDC (9.2 mg/kg body wt, intraperitoneal) treatment along with Cd (6 mg/kg body wt) enhanced Cd accumulation in cerebral cortices of treated animals resulting in an increased inhibition of CaM and CaM dependent enzymes. These data suggest that Cd may be acting via binding to CaM and uncoupling it from its normal cellular control of calcium.