Meu10 is required for spore wall maturation in Schizosaccharomyces pombe

BACKGROUND: Many genes are meiosis and/or sporulation-specifically transcribed during this process. Isolation and analysis of these genes might help us to understand how meiosis and sporulation are regulated. For this purpose, we have isolated a large number of cDNA clones from Schizosaccharomyces pombe whose expression is up-regulated during meiosis. RESULTS: We have isolated meu10+ gene, which encodes 416 amino acids and bears homology to SPS2 of Saccharomyces cerevisiae. A strain whose meu10+ gene has been deleted forms no viable spores. Thin-section electron micrographs showed that the meu10Delta strain has abnormally formed spore walls, and then they disrupt, allowing cytoplasmic material to escape. The Meu10-GFP fusion protein is localized to the spore periphery, thereafter returned to the cytoplasm after sporulation. Meu10-GFP localization to the spore wall was almost normal in the bgs2Delta or chs1Delta mutants that lack 1,3-beta-glucan or chitin, respectively. In contrast, 1,3-beta-glucan is abnormally localized in meu10Delta cells. Meu10 has an N-terminal domain with homology to the mammalian insulin receptor and a C-terminal domain with a transmembrane motif. Mutants whose N-terminal or C-terminal domain was truncated were severely defective for sporulation. CONCLUSIONS: Meu10 is a spore wall component and plays a pivotal role in the formation of the mature spore wall structure.     

Geographic differentiation of polymorphism in the Plasmodium falciparum malaria vaccine candidate gene SERA5

SERA5 is regarded as a promising malaria vaccine candidate of the most virulent human malaria parasite Plasmodium falciparum. SERA5 is a 120 kDa abundantly expressed blood-stage protein containing a papain-like protease. Since substantial polymorphism in blood-stage vaccine candidates may potentially limit their efficacy, it is imperative to fully investigate polymorphism of the SERA5 gene (sera5). In this study, we performed evolutionary and population genetic analysis of sera5. The level of inter-species divergence (kS=0.076) between P. falciparum and Plasmodium reichenowi, a closely related chimpanzee malaria parasite is comparable to that of housekeeping protein genes. A signature of purifying selection was detected in the proenzyme and enzyme domains. Analysis of 445 near full-length P. falciparum sera5 sequences from nine countries in Africa, Southeast Asia, Oceania and South America revealed extensive variations in the number of octamer repeat (OR) and serine repeat (SR) regions as well as substantial level of single nucleotide polymorphism (SNP) in non-repeat regions (2562 bp). Remarkably, a 14 amino acid sequence of SERA5 (amino acids 59-72) that is known to be the in vitro target of parasite growth inhibitory antibodies was found to be perfectly conserved in all 445 worldwide isolates of P. falciparum evaluated. Unlike other major vaccine target antigen genes such as merozoite surface protein-1, apical membrane antigen-1 or circumsporozoite protein, no strong evidence for positive selection was detected for SNPs in the non-repeat regions of sera5. A biased geographical distribution was observed in SNPs as well as in the haplotypes of the sera5 OR and SR regions. In Africa, OR- and SR-haplotypes with low frequency (<5%) and SNPs with minor allele frequency (<5%) were abundant and were mostly continent-specific. Consistently, significant genetic differentiation, assessed by the Wright's fixation index (Fst) of inter-population variance in allele frequencies, was detected for SNPs and both OR- and SR-haplotypes among almost all parasite populations. The exception was parasite populations between Tanzania and Ghana, suggesting frequent gene flow in Africa. The present study points to the importance of investigating whether biased geographical distribution for SNPs and repeat variants in the OR and SR regions affect the reactivity of human serum antibodies to variants.     

Magnetic resonance imaging of developmental facial paresis: a spectrum of complex anomalies

Neuroradiology - Despite its clinical implications, the MRI features of developmental facial paresis (DFP) were described in a few case reports. This study aims to describe MRI features of DFP in...     

Two new sarpagine-type indole alkaloids and antimalarial activity of 16-demethoxycarbonylvoacamine from Tabernaemontana macrocarpa Jack

Journal of Natural Medicines - Two new sarpagine-type indole alkaloids (1 and 2), together with five known alkaloids; 12-methoxy-4-methylvoachalotine (3), 16-demethoxycarbonylvoacamine (4),...     

Chukranoids A–I,isopimarane diterpenoids from Chukrasia velutina

Journal of Natural Medicines - Bioactivity guided separation of Chukrasia velutina root methanolic extract led to the isolation of nine new isopimarane diterpenoids, chukranoids A–I...     

Leucophyllinines A and B,bisindole alkaloids from Leuconotis eugeniifolia

Two new bisindole alkaloids, leucophyllinines A (1) and B (2) consisting of eburnane and quebrachamine-type skeletons were isolated from the bark of Leuconotis eugeniifolia, and their structures were elucidated on the basis of spectroscopic data. Leucophyllinines A and B showed antiplasmodial activities against Plasmodium falciparum 3D7.

     

Within-population genetic diversity of Plasmodium falciparum vaccine candidate antigens reveals geographic distance from a Central sub-Saharan African origin

Populations of Plasmodium falciparum, the most virulent human malaria parasite, are diverse owing to wide levels of transmission and endemicity of infection. Genetic diversity of P. falciparum antigens, within and between parasite populations, remains a confounding factor in malaria pathogenesis as well as clinical trials of vaccine candidates. Variation of target antigens in parasite populations may arise from immune pressure depending on the levels of acquired immunity. Alternatively, similar to our study in housekeeping genes [Tanabe et al. Curr Biol 2010;70:1–7], within-population genetic diversity of vaccine candidate antigens may also be determined by geographical distance from a postulated origin in Central sub-Saharan Africa. To address this question, we obtained full-length sequences of P. falciparum genes, apical membrane antigen 1 (ama1) (n = 459), circumsporozoite protein (csp) (n = 472) and merozoite surface protein 1 (msp1) (n = 389) from seven geographically diverse parasite populations in Africa, Southeast Asia and Oceania; and, together with previously determined sequences (n = 13 and 15 for csp and msp1, respectively) analyzed within-population single nucleotide polymorphism (SNP) diversity. The three antigen genes showed SNP diversity that supports a model of isolation-by-distance. The standardized number of polymorphic sites per site, expressed as θ_S, indicates that 77–83% can be attributed by geographic distance from the African origin, suggesting that geographic distance plays a significant role in variation in target vaccine candidate antigens. Furthermore, we observed that a large proportion of SNPs in the antigen genes were shared between African and non-African parasite populations, demonstrating long term persistence of those SNPs. Our results provide important implications for developing effective malaria vaccines and better understanding of acquired immunity against falciparum malaria.     

Bisindole alkaloids from Voacanga grandifolia leaves

Journal of Natural Medicines - Two new bisindole alkaloids, 12′-O-demethyl-vobtusine-5-lactam and isovobtusine-N-oxide (1 and 2), were isolated from the leaves of Voacanga grandifolia,...     

Direct Metagenomic Detection of Viral Pathogens in Nasal and Fecal Specimens Using an Unbiased High-Throughput Sequencing Approach

With the severe acute respiratory syndrome epidemic of 2003 and renewed attention on avian influenza viral pandemics, new surveillance systems are needed for the earlier detection of emerging infectious diseases. We applied a “next-generation” parallel sequencing platform for viral detection in nasopharyngeal and fecal samples collected during seasonal influenza virus (Flu) infections and norovirus outbreaks from 2005 to 2007 in Osaka, Japan. Random RT-PCR was performed to amplify RNA extracted from 0.1–0.25 ml of nasopharyngeal aspirates (N=3) and fecal specimens (N=5), and more than 10 µg of cDNA was synthesized. Unbiased high-throughput sequencing of these 8 samples yielded 15,298–32,335 (average 24,738) reads in a single 7.5 h run. In nasopharyngeal samples, although whole genome analysis was not available because the majority (>90%) of reads were host genome–derived, 20–460 Flu-reads were detected, which was sufficient for subtype identification. In fecal samples, bacteria and host cells were removed by centrifugation, resulting in gain of 484–15,260 reads of norovirus sequence (78–98% of the whole genome was covered), except for one specimen that was under-detectable by RT-PCR. These results suggest that our unbiased high-throughput sequencing approach is useful for directly detecting pathogenic viruses without advance genetic information. Although its cost and technological availability make it unlikely that this system will very soon be the diagnostic standard worldwide, this system could be useful for the earlier discovery of novel emerging viruses and bioterrorism, which are difficult to detect with conventional procedures.