Inhibitors of Plasmepsin II-potential antimalarial agents

In order to overcome the problem of drug resistance in malaria, it appears wise to concentrate drug discovery efforts toward new structural classes and new mechanisms of action. We report our results, targeting Plasmepsin II, a Plasmodium falciparum aspartic protease active in hemoglobin degradation, a parasite specific catabolic pathway. The results show that the new structural class is not only inhibiting PMII in vitro but is also active in a P. falciparum infected human red blood cell assay.     

Polarity and temporality of high-resolution y-chromosome distributions in India identify both indigenous and exogenous expansions and reveal minor genetic influence of Central Asian pastoralists

Although considerable cultural impact on social hierarchy and language in South Asia is attributable to the arrival of nomadic Central Asian pastoralists, genetic data (mitochondrial and Y chromosomal) have yielded dramatically conflicting inferences on the genetic origins of tribes and castes of South Asia. We sought to resolve this conflict, using high-resolution data on 69 informative Y-chromosome binary markers and 10 microsatellite markers from a large set of geographically, socially, and linguistically representative ethnic groups of South Asia. We found that the influence of Central Asia on the pre-existing gene pool was minor. The ages of accumulated microsatellite variation in the majority of Indian haplogroups exceed 10,000-15,000 years, which attests to the antiquity of regional differentiation. Therefore, our data do not support models that invoke a pronounced recent genetic input from Central Asia to explain the observed genetic variation in South Asia. R1a1 and R2 haplogroups indicate demographic complexity that is inconsistent with a recent single history. Associated microsatellite analyses of the high-frequency R1a1 haplogroup chromosomes indicate independent recent histories of the Indus Valley and the peninsular Indian region. Our data are also more consistent with a peninsular origin of Dravidian speakers than a source with proximity to the Indus and with significant genetic input resulting from demic diffusion associated with agriculture. Our results underscore the importance of marker ascertainment for distinguishing phylogenetic terminal branches from basal nodes when attributing ancestral composition and temporality to either indigenous or exogenous sources. Our reappraisal indicates that pre-Holocene and Holocene-era--not Indo-European--expansions have shaped the distinctive South Asian Y-chromosome landscape.     

Lipocalin 2 regulation by thermal stresses: Protective role of Lcn2/NGAL against cold and heat stresses

Environmental temperature variations are the most common stresses experienced by a wide range of organisms. Lipocalin 2 (Lcn2/NGAL) is expressed in various normal and pathologic conditions. However, its precise functions have not been fully determined. Here we report the induction of Lcn2 by thermal stresses in vivo, and its role following exposure to cold and heat stresses in vitro. Induction of Lcn2 in liver, heart and kidney was detected by RT-PCR, Western blot and immunohistochemistry following exposure of mice to heat and cold stresses. When CHO and HEK293T cells overexpressing NGAL were exposed to cold stress, cell proliferation was higher compared to controls. Down-regulatrion of NGAL by siRNA in A549 cells resulted in less proliferation when exposed to cold stress compared to control cells. The number of apoptotic cells and expression of pro-apoptotic proteins were lower in the NGAL overexpressing CHO and HEK293T cells, but were higher in the siRNA-transfected A549 cells compared to controls, indicating that NGAL protects cells against cold stress. Following exposure of the cells to heat stress, ectopic expression of NGAL protected cells while addition of exogenous recombinant NGAL to the cell culture medium exacerbated the toxicity of heat stress specially when there was low or no endogenous expression of NGAL. It had a dual effect on apoptosis following heat stress. NGAL also increased the expression of HO-1. Lcn2/NGAL may have the potential to improve cell proliferation and preservation particularly to prevent cold ischemia injury of transplanted organs or for treatment of some cancers by hyperthermia.     

Elevated atmospheric CO2 concentration ameliorates effects of NaCl salinity on photosynthesis and leaf structure of Aster tripolium L.

This study investigated the interaction of NaCl-salinity andelevated atmospheric CO₂ concentration on gas exchange, leafpigment composition, and leaf ultrastructure of the potentialcash crop halophyte Aster tripolium. The plants were irrigatedwith five different salinity levels (0, 25, 50, 75, 100% seawatersalinity) under ambient and elevated (520 ppm) CO₂. Under salineconditions (ambient CO₂) stomatal and mesophyll resistance increased,leading to a significant decrease in photosynthesis and wateruse efficiency (WUE) and to an increase in oxidative stress.The latter was indicated by dilations of the thylakoid membranesand an increase in superoxide dismutase (SOD) activity. Oxidativestress could be counteracted by thicker epidermal cell wallsof the leaves, a thicker cuticle, a reduced chlorophyll content,an increase in the chlorophyll a/b ratio and a transient declineof the photosynthetic efficiency. Elevated CO₂ led to a significantincrease in photosynthesis and WUE. The improved water and energysupply was used to increase the investment in mechanisms reducingwater loss and oxidative stress (thicker cell walls and cuticles,a higher chlorophyll and carotenoid content, higher SOD activity),resulting in more intact thylakoids. As these mechanisms canimprove survival under salinity, A. tripolium seems to be apromising cash crop halophyte which can help in desalinizingand reclaiming degraded land. Key words: Aster tripolium, cash crop halophyte, elevated CO₂, gas exchange, oxidative stress, photosynthesis, salt tolerance, ultrastructure, water use efficiency Received 29 July 2008; Revised 8 October 2008 Accepted 9 October 2008     

Resistance and susceptibility of some wheat lines to bird cherry-oat aphid <Emphasis Type="Italic">Rhopalosiphum padi</Emphasis> (Hemiptera: Aphididae)

Bird cherry-oat aphid, Rhopalosiphum padi (L.), is one of the most serious pests of cereals, with an almost worldwide distribution. A primary screening test was carried out to gauge the resistance or susceptibility of 40 wheat lines to R. padi, and follow-up experiments were conducted to determine the development and fecundity rates of R. padi on eight lines. The forty wheat lines examined were classified into two major classes and four subclasses: A (e.g., ERWYT 87-1) and B (e.g., ERWYT 87-20, ERWYT 87-11), with the highest average number of aphids 14 days after infestation, subclass C (e.g., ERWYT 88-8, ERWYT 87-6, ERWYT 87-4), with the lowest average number of aphids, and subclass D (e.g., ERWYT 88-12, ERWYT 88-13), with intermediate status. Aphid nymph developmental time and survival both differed among the wheat lines. Differences were also observed in the fecundity of R. padi, the intrinsic rate of increase (r _m), and other parameters among the wheat lines tested. The highest and lowest values of r _m were obtained for ERWYT 87-1 and ERWYT 88-8 (0.36 and 0.26 nymphs/female/day, respectively). Three lines (ERWYT 87-4, ERWYT 87-6, ERWYT 88-8) were relatively resistant to R. padi, which could prove useful in the development of IPM programs for this aphid in wheat fields.     

Karyotype analysis and new chromosome number reports in <Emphasis Type="Italic">Achillea</Emphasis> species

Cytological analyses were performed in nineteen accessions belonging to seven Achillea species. The results indicate that two species, A. filipendulina and A. tenuifolia, are diploid (2n = 2x = 18) and three species, A. bieberstinii, A. pachycephala, and A. aucheri are tetraploid (2n = 4x = 36). For two latter species, the chromosome numbers are new. Two ploidy levels of 2n = 6x = 54 and 2n = 8x = 72 in A. millefolium and two ploidy levels of 2n = 2x = 18 and 2n = 4x = 36 in A. santolina species were found. Cluster analysis based on chromosomal characteristics and karyotype asymmetry indices clustered the studied genotypes into three major groups. The first group included the diploid species (A. filipendulina, A. santolina and A. tenufolia), while the second group comprised tetraploid species (A. santolina, A. aucheri and A. pachycephala). A. millefolium (hexaploid, octaploid) and A. bieberstinii (tetraploid) were classified in the third group. Total form percentage (TF%) in groups 1, 2 and 3 were 42.03, 42.15 and 41.08, respectively. Group 1 possessed the highest average of symmetry index (S% = 70.8). Stebbins classification method grouped all accessions in class A. Moreover, group 1 (diploid level species), had the most symmetric karyotype from point of view of centromere and chromosome length. Therefore, it can be concluded that the genotypes belonging to group 1 are the earliest evolutionary form.     

Analyzing Multiple‐Probe Microarray: Estimation and Application of Gene Expression Indexes

Summary Gene expression index estimation is an essential step in analyzing multiple probe microarray data. Various modeling methods have been proposed in this area. Amidst all, a popular method proposed in Li and Wong (2001) is based on a multiplicative model, which is similar to the additive model discussed in Irizarry et al. (2003a) at the logarithm scale. Along this line, Hu et al. (2006) proposed data transformation to improve expression index estimation based on an ad hoc entropy criteria and naive grid search approach. In this work, we re‐examined this problem using a new profile likelihood‐based transformation estimation approach that is more statistically elegant and computationally efficient. We demonstrate the applicability of the proposed method using a benchmark Affymetrix U95A spiked‐in experiment. Moreover, We introduced a new multivariate expression index and used the empirical study to shows its promise in terms of improving model fitting and power of detecting differential expression over the commonly used univariate expression index. As the other important content of the work, we discussed two generally encountered practical issues in application of gene expression index: normalization and summary statistic used for detecting differential expression. Our empirical study shows somewhat different findings from the MAQC project ( MAQC, 2006 ).     

Post-translational modifications of Hsp90 and their contributions to chaperone regulation

Molecular chaperones, as the name suggests, are involved in folding, maintenance, intracellular transport, and degradation of proteins as well as in facilitating cell signaling. Heat shock protein 90 (Hsp90) is an essential eukaryotic molecular chaperone that carries out these processes in normal and cancer cells. Hsp90 function in vivo is coupled to its ability to hydrolyze ATP and this can be regulated by co-chaperones and post-translational modifications. In this review, we explore the varied roles of known post-translational modifications of cytosolic and nuclear Hsp90 (phosphorylation, acetylation, S-nitrosylation, oxidation and ubiquitination) in fine-tuning chaperone function in eukaryotes. This article is part of a Special Issue entitled: Heat Shock Protein 90 (HSP90).     

Trichomonas vaginalis: Investigation of a novel diagnostic method in urine samples using cysteine proteinase 4 gene and PCR technique

Trichomonas vaginalis is the agent of a highly prevalent sexually transmitted disease that leads to vaginitis, urethritis, ectocervicitis and has been associated with human immunodeficiency virus (HIV). Detection of T. vaginalis based on wet-mount microscopy and culture methods is insensitive and time consuming, respectively. Thus the quest for reliable PCR techniques of T. vaginalis in vaginal discharge and urine sample is more importance. In this study, 500 urine and vaginal-discharge samples were collected from women referred to Sexual Transmitted Disease Clinic of Mirzakuchakkhan Hospital in Tehran, Iran between May 2008 and March 2009. Wet-mount and culture methods were done on the vaginal discharges, and PCR assay targeting cysteine proteinase 4 (CP4) was performed on the urine samples. The present study demonstrated 16 (3.2%) of patients were infected with T. vaginalis using culture and wet-mount, whereas PCR assay using CP4 could detect 12 (2.4%) positivity. Sensitivity and specificity of urine PCR assay compared to culture were 80% (95% CI, 54-96) and 99.6% (95% CI, 98.96-100), respectively. These results indicate that using urine-based detection method for T. vaginalis may not be appropriate in women.     

An antagonism between the AKT and beta-adrenergic signaling pathways mediated through their reciprocal effects on miR-199a-5p

We have recently reported that downregulation of miR-199a-5p is necessary and sufficient for inducing upregulation of its targets, including hypoxia-inducible factor-1alpha (Hif-1α) and Sirt1, during hypoxia preconditioning (HPC). Conversely, others and we have reported that miR-199a-5p is upregulated during cardiac hypertrophy. Thus, the objective of this study was to delineate the signaling pathways that regulate the expression of miR-199a-5p and its targets, and their role in myocyte survival during hypoxia. Since HPC is mediated through activation of the AKT pathway, we questioned if AKT is sufficient for inducing downregulation of miR-199a-5p. Our present study shows that overexpression of a constitutively active AKT (caAKT) induced 70% reduction in miR-199a-5p and was associated with a robust increase in HiF-1α (10 ± 2 fold) and Sirt1 (4 ± 0.8 fold) that was reversed by overexpression of miR-199a-5p. Similarly, insulin receptor-stimulated activation of the AKT pathway induced downregulation of miR-199a-5p and upregulation of its targets. In contrast, β-adrenergic receptor (βAR) activation in vitro and in vivo, induced 1.8–3.5-fold increase in miR-199a-5p. Accordingly, we predicted that βAR would antagonize AKT-induced, miR-199a-5p-dependent, upregulation of Hif-1α and Sirt1. Indeed, pre-treating the myocytes with isoproterenol before applying HPC, caAKT, or insulin resulted in 87 ± 3%, 75 ± 15%, and 100% reductions in Hif-1α expression, respectively, and sensitized the cells to hypoxic injury. Thus, activation of beta-adrenergic signaling counteracts the survival effects of the AKT pathway via upregulating miR-199a-5p.