Malaria: therapy, genes and vaccines

Malaria kills over 3,000 children each day. Modern molecular and biochemical approaches are being used to help understand and control Plasmodium falciparum, the parasite that causes this deadly disease. New drugs are being invented for both chemoprophylaxis and therapeutic treatments and their use is discussed along side that of the more commonly used treatments. Classical genetic crosses coupled with molecular analysis of gene loci are use to explain the genetics behind the development of specific drug resistances that the parasites have naturally developed. Rapid advances in DNA sequencing techniques have allowed the compete sequencing of the P. falciparum and several other rodent malaria parasite genomes. Proteomics and computational analysis of these vast databanks are being used to model and investigate the three-dimensional structure of many key malaria proteins in an attempt to facilitate drug design. Recombinant protein expression in bacteria and yeast coupled with cGMP purification technologies and conditions have lead to the recent availability of several dozen malaria protein antigens for human-use Phase I and Phase II vaccine trials. Drug companies, private foundations, and key government agencies have contributed to the coordinated efforts needed to test these antigens, adjuvants and delivery methods in an effort to find an effective malaria vaccine that will prevent infection and disease.     

Proapoptotic effects of NARC 1 (= PCSK9), the gene encoding a novel serine proteinase.

BACKGROUND: NARC 1/PCSK9 encodes a novel serine proteinase known to play a role in cholesterol homeostasis. NARC 1 mRNA expression in cerebellar granule neurons (CGNs) was discovered to be induced following an apoptotic injury. Coregulation of known apoptotic mediators (caspase-3 and death receptor 6) raises the possibility that NARC 1 might be involved in the propagation of apoptotic signaling in neurons. METHODS: CGNs were transfected with EGFP-fusion constructs of wild-type and mutant NARC 1, and a laser scanning cytometry-based method of scoring cell death in transfectants was applied. Use of the poly-caspase inhibitor BAF allowed assessment of the caspase-dependence of the NARC 1 proapoptotic effect. RESULTS: Wild-type NARC 1 was found to have substantial proapoptotic effects that were only partially reversible by BAF. Mutation of the active site serine or deletion of the catalytic domain resulted in a reduced level of cell death, consistent with loss of the BAF-sensitive component of cell death. NH(2)-terminal deletion constructs of NARC 1 had effects similar to wild-type, both in the absence and presence of BAF, whereas expression of COOH-terminal deletion mutants produced a rate of cell death similar to wild-type in the absence of BAF treatment, but which lacked the capacity to be reduced by treatment with BAF. CONCLUSION: The mechanism by which NARC 1-EGFP over-expression induces cell death in cultured CGNs remains unclear. Mutation analysis established a positive correlation between the presence of the Narc 1 active site serine in the transiently expressed protein and induction of the BAF-sensitive component of the cell death phenotype. A caspase-independent component proved sufficiently complex to map discretely within the Narc 1 protein.     

Contrasting phylogeographical patterns between mainland and island taxa of the Pinus luchuensis complex

Species whose geographical distribution encompasses both mainland and island populations provide an ideal system for examining isolation and genetic divergence. In this study, paternally transmitted chloroplast DNA (cpDNA) and maternally transmitted mitochondrial DNA (mtDNA) were used to estimate population structure and phylogeography of Pinus luchuensis, a species found in eastern China (ssp. hwangshanensis), Taiwan (ssp. taiwanensis), and the Ryukyu Archipelago (ssp. luchuensis). Gene genealogies of both mtDNA and cpDNA reveal two major lineages. Molecular dating indicates that these lineages diverged before the colonization of P. luchuensis subspecies in Taiwan and the Ryukyu Archipelago. Both mtDNA and cpDNA show a lack of correspondence between molecular phylogeny and subspecies designation. Phylogeographical analysis suggests that paraphyly of the subspecies is the result of recent divergence rather than secondary contacts. In spite of the short divergence history of P. luchuensis on islands, the island populations show the same degree of genetic divergence as mainland populations. Low levels of genetic diversity in the mainland ssp. hwangshanensis suggest demographic bottlenecks. In contrast, the high heterogeneity of genetic composition for island populations is likely to be associated with a history of multiple colonization from the mainland. The spatial apportionment of organelle DNA polymorphisms is consistent with a pattern of stepwise colonization on island populations.     

Cutting edge: novel human dendritic cell- and monocyte-attracting chemokine-like protein identified by fold recognition methods

Chemokines play an important role in the immune system by regulating cell trafficking in homeostasis and inflammation. In this study, we report the identification and characterization of a novel cytokine-like protein, DMC (dendritic cell and monocyte chemokine-like protein), which attracts dendritic cells and monocytes. The key to the identification of this putative new chemokine was the application of threading techniques to its uncharacterized sequence. Based on our studies, DMC is predicted to have an IL-8-like chemokine fold and to be structurally and functionally related to CXCL8 and CXCL14. Consistent with our predictions, DMC induces migration of monocytes and immature dendritic cells. Expression studies show that DMC is constitutively expressed in lung, suggesting a potential role for DMC in recruiting monocytes and dendritic cells from blood into lung parenchyma.     

A flexible computational framework for detecting, characterizing, and interpreting statistical patterns of epistasis in genetic studies of human disease susceptibility

Detecting, characterizing, and interpreting gene-gene interactions or epistasis in studies of human disease susceptibility is both a mathematical and a computational challenge. To address this problem, we have previously developed a multifactor dimensionality reduction (MDR) method for collapsing high-dimensional genetic data into a single dimension (i.e. constructive induction) thus permitting interactions to be detected in relatively small sample sizes. In this paper, we describe a comprehensive and flexible framework for detecting and interpreting gene-gene interactions that utilizes advances in information theory for selecting interesting single-nucleotide polymorphisms (SNPs), MDR for constructive induction, machine learning methods for classification, and finally graphical models for interpretation. We illustrate the usefulness of this strategy using artificial datasets simulated from several different two-locus and three-locus epistasis models. We show that the accuracy, sensitivity, specificity, and precision of a na?ve Bayes classifier are significantly improved when SNPs are selected based on their information gain (i.e. class entropy removed) and reduced to a single attribute using MDR. We then apply this strategy to detecting, characterizing, and interpreting epistatic models in a genetic study (n = 500) of atrial fibrillation and show that both classification and model interpretation are significantly improved.     

Effects of 900 MHz GSM wireless communication signals on DMBA-induced mammary tumors in rats

The purpose of the study was to investigate whether exposure to 900 MHz GSM wireless communication signals enhances mammary tumor development and growth induced by low-dose DMBA. Five hundred female Sprague-Dawley rats were treated with a single dose of 35 mg/kg DMBA and then divided into five groups in a blinded fashion: one cage control group and four exposure groups, including three microwave exposure groups and one sham exposure with specific absorption rates (SARs) of 4.0, 1.33, 0.44 and 0 W/kg, respectively. Exposure started on the day after DMBA administration and lasted 4 h/day, 5 days/week for 26 weeks. Rats were weighed and palpated weekly for the presence of tumors and were killed humanely at the end of the 26-week exposure period. All mammary glands were examined histologically. There were no statistically significant differences in body weight between sham- and GSM microwave-exposed groups. No significant differences in overall mammary tumor incidence, latency to tumor onset, tumor multiplicity, or tumor size were observed between microwave- and sham-exposed groups. There was a tendency for reduction of mammary adenocarcinoma incidence in the lowest microwave exposure group (0.44 W/ kg) compared with the sham-exposed group (P = 0.058). Additionally, a higher incidence of adenocarcinoma was noticed in the 4.0 W/kg group from the 15th to 26th weeks, especially in the 19th week (P = 0.358 compared to sham). However, neither tendency was statistically significant; thus this study does not provide evidence that GSM microwave exposure promotes mammary tumor development in rats. In the present study there were significant differences between the cage controls and the experimental groups (sham and exposure). Body weight and mammary tumor (malignant plus benign) incidence in the cage control group were significantly higher than in the sham- and GSM microwave-exposed groups. The latency to the mammary tumor onset was significantly shorter in the cage control group than in the other groups.     

Taxonomic re-assessment of <Emphasis Type="Italic">Phaseolus dasycarpus</Emphasis> (Leguminosae): Systematic position,chromosome studies and re-description

Based on new information on floral structures, seedling, fruit, seed, root, and leaflet characters, Phaseolus dasycarpus is re-described and illustrated. Its chromosome number was determined as 2n  = 22, with metacentric and submetacentric chromosomes, and karyotype formula of 9m + 2sm. Previous phylogenetic analyses of ITS and trnK sequence data, and those obtained in the present study, show P. dasycarpus to be aligned within section Pedicellati.

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Resumen  Con nueva información de estructuras florales, plántulas, frutos, semillas, raíz y folíolos, se redescribe e ilustra a Phaseolus dasycarpus. Se determina el número cromosómico 2n  = 22, con cromosomas metacéntricos y submetacéntricos y fórmula cariotípica = 9m + 2sm. Análisis filogenéticos previos con secuencias de ITS y trnK y los resultados obtenidos en el presente estudio, establecen a P. dasycarpus en la sección Pedicellati.

     

Andrographolide could inhibit human colorectal carcinoma Lovo cells migration and invasion via down-regulation of MMP-7 expression

Andrographolide (Andro), a diterpenoid lactone isolated from a traditional herbal medicine Andrographis paniculata, is known to possess multiple pharmacological activities. In our previous study, Andro had been shown to have potent anti-cancer activity against human colorectal carcinoma Lovo cells by inhibiting cell-cycle progression. To further investigate the mechanism for the anti-cancer properties of Andro, it was used to examine the effect on migration and invasion of Lovo cells. The results of wound-healing assay and in vitro transwell assay revealed that Andro inhibited dose-dependently the migration and invasion of Lovo cells under non-cytotoxic concentrations. Using zymographic assay and RT-PCR, the results revealed that Andro diminished the activity and the mRNA and protein levels of MMP-7, but not MMP-2 or MMP-9. The down-regulation of MMP-7 appeared to be via the inactivation of activator protein-1 (AP-1) since the treatment with Andro suppressed the nuclear protein level of AP-1, which was accompanied by a decrease in DNA-binding level of the factor. Taken together, these results indicated that Andro reduces the MMP-7-mediated cellular events in Lovo cells, and provided a new mechanism for its anti-cancer activity.