Investigation of a requirement for the PsbP-like protein in Synechocystis sp. PCC 6803

The sll1418 gene encodes a PsbP-like protein in Synechocystis sp. PCC 6803. Expression of sll1418 was similar in BG-11 and in Cl⁻- or Ca²⁺-limiting media, and inactivation of sll1418 did not prevent photoautotrophic growth in normal or nutrient-limiting conditions. Also the wild-type and ΔPsbP strains exhibited similar oxygen evolution and assembly of Photosystem II (PS II) centers. Inactivation of sll1418 in the ΔPsbO: ΔPsbP, ΔPsbQ:ΔPsbP, ΔPsbU:ΔPsbP and ΔPsbV:ΔPsbP mutants did not prevent photoautotrophy or alter PS II assembly and oxygen evolution in these strains. Moreover, the absence of PsbP did not affect the ability of alkaline pH to restore photoautotrophic growth in the ΔPsbO:ΔPsbU strain. The PsbO, PsbU and PsbV proteins are required for thermostability of PS II and thermal acclimation in Synechocystis sp. PCC 6803 [Kimura et al. (2002) Plant Cell Physiol 43: 932–938]. However, thermostability and thermal acclimation in ΔPsbP cells were similar to wild type. These results are consistent with the conclusion that PsbP is associated with ∼3 of PS II centers, and may play a regulatory role in PS II [Thornton et al. (2004) Plant Cell 16: 2164–2175].     

Potato Expressed Sequence Tag Generation and Analysis using Standard and Unique cDNA Libraries

To help develop an understanding of the genes that govern the developmental characteristics of the potato (Solanum tuberosum), as well as the genes associated with responses to specified pathogens and storage conditions, The Canadian Potato Genome Project (CPGP) carried out 5′ end sequencing of regular, normalized and full-length cDNA libraries of the Shepody potato cultivar, generating over 66,600 expressed sequence tags (ESTs). Libraries sequenced represented tuber developmental stages, pathogen-challenged tubers, as well as leaf, floral developmental stages, suspension cultured cells and roots. All libraries analysed to date have contributed unique sequences, with the normalized libraries high on the list. In addition, a low molecular weight library has enhanced the 3′ ends of our sequence assemblies. Using the combined assembly dataset, unique tuber developmental, cold storage and pathogen-challenged sequences have been identified. A comparison of the ESTs specific to the pathogen-challenged tuber and foliar libraries revealed minimal overlap between these libraries. Mixed assemblies using over 189,000 potato EST sequences from CPGP and The Institute for Genomics Research (TIGR) has revealed common sequences, as well as CPGP- and TIGR-unique sequences. Electronic Supplementary Material Electronic Supplementary material is available for this article at and accessible for authorised users.     

Quantitative appraisal of murine filariasis confirms host strain differences but reveals that BALB/c females are more susceptible than males to Litomosoides sigmodontis

Litomosoides sigmodontis, a rodent filarial nematode, can infect inbred laboratory mice, with full development to patency in the BALB/c strain. Strains such as C57BL/6 are considered resistant, because although filarial development can occur, circulating microfilariae are never detected. This model system has, for the first time, allowed the power of murine immunology to be applied to fundamental questions regarding susceptibility to filarial nematode infection. As this is a relatively new model, many aspects of the biology remain to be discovered or more clearly defined. We undertook a major analysis of 85 experiments, to quantitatively assess differences in filarial survival and reproduction in male versus female and BALB/c versus C57BL/6 mice over the full course of infection. This large dataset provided hard statistical support for previous qualitative reviews, including observations that the resistant phenotype of C57BL/6 mice is detectable as early as 10 days postinfection (dpi). An unexpected finding, however, was that filarial survival was reduced in male BALB/c mice compared to their female counterparts. Worm recovery as well as the prevalence and density of microfilariae were higher in female compared with male BALB/c mice. Therefore, L. sigmodontis bucks the filarial trend of increased susceptibility in males. This could be partially explained by the different anatomical locations of adult L. sigmodontis versus lymphatic filariae. Interestingly, the effects of BALB/c sex upon microfilaremia were independent of worm number. In summary, this study has significantly refined our understanding of the host-L. sigmodontis relationship and, critically, has challenged the dogma that males are more susceptible to filarial infection.     

Structure-activity relationships of 1,3,5-triazine-2,4,6-triones as human gonadotropin-releasing hormone receptor antagonists

SAR studies of 1,3,5-triazine-2,4,6-triones as human gonadotropin-releasing hormone receptor antagonists resulted in potent compounds. The best compound from the series had a binding affinity of 2 nM.     

Prioritizing multiple-use landscapes for conservation: methods for large multi-species planning problems

Across large parts of the world, wildlife has to coexist with human activity in highly modified and fragmented landscapes. Combining concepts from population viability analysis and spatial reserve design, this study develops efficient quantitative methods for identifying conservation core areas at large, even national or continental scales. The proposed methods emphasize long-term population persistence, are applicable to both fragmented and natural landscape structures, and produce a hierarchical zonation of regional conservation priority. The methods are applied to both observational data for threatened butterflies at the scale of Britain and modelled probability of occurrence surfaces for indicator species in part of Australia. In both cases, priority landscapes important for conservation management are identified.     

Synthesis and in vitro anti-mycobacterial activity of 5-substituted pyrimidine nucleosides

Mycobacterium tuberculosis and Mycobacterium avium infections cause the two most important mycobacterioses, leading to increased mortality in patients with AIDS. Various 5-substituted 2′-deoxyuridines, uridines, 2′-O-methyluridine, 2′-ribofluoro-2′-deoxyuridines, 3′-substituted-2′,3′-dideoxy uridines, 2′,3′-dideoxyuridines, and 2′,3′-didehydro-2′,3′-dideoxyuridines were synthesized and evaluated for their in vitro inhibitory activity against M. bovis and M. avium. 5-(C-1 Substituted)-2′-deoxyuridine derivatives emerged as potent inhibitors of M. avium (MIC₉₀ = 1–5 μg/mL range). The nature of C-5 substituents in the 2′-deoxyuridine series appeared to be a determinant of anti-mycobacterial activity. This new class of inhibitors could serve as useful compounds for the design and study of new anti-tuberculosis agents.     

ABC transporter FtsABCD of <Emphasis Type="Italic">Streptococcus pyogenes</Emphasis> mediates uptake of ferric ferrichrome

Background  

The Streptococcus pyogenes or Group A Streptococcus (GAS) genome encodes three ABC transporters, namely, FtsABCD, MtsABC, and HtsABC, which share homology with iron transporters. MtsABC and HtsABC are believed to take up ferric (Fe³⁺) and manganese ions and heme, respectively, while the specificity of FtsABCD is unknown.     

Muscle-derived stem cells: implications for effective myoblast transfer therapy

Stem cells have been proposed as a wonder solution for tissue repair in many situations and have attracted much attention in the media for both their therapeutic potential and ethical implications. In addition to the excitement generated by embryonic stem cells, research has now identified a number of stem cells within adult tissues which pose much more realistic targets for therapeutic interventions. Myoblast transfer therapy (MTT) has long been viewed as a potential therapy for the debilitating muscle-wasting disorder Duchenne Muscular Dystrophy. This technique relies on the transplantation of committed muscle precursor cells directly into the muscle fibres but has had little success in clinical trials. The recent discovery of a population of cells within adult muscle with stem cell-like characteristics has interesting implications for the future of such putative cell transplantation therapies. This review focuses on the characterization and application of these potential muscle-derived stem cells (MDSC) to MTT.     

HIV-1 Nef disrupts antigen presentation early in the secretory pathway

Human immunodeficiency virus, type 1 Nef disrupts viral antigen presentation and promotes viral immune evasion from cytotoxic T lymphocytes. There is evidence that Nef acts early in the secretory pathway to redirect major histocompatibility complex class I (MHC-I) from the trans-Golgi network to the endolysosomal pathway. However, a competing model suggests that Nef acts much later by accelerating MHC-I turnover at the cell surface. Here we demonstrate that Nef targets early forms of MHC-I molecules in the endoplasmic reticulum by preferentially binding hypophosphorylated cytoplasmic tails. The Nef-MHC-I complex migrates normally into the Golgi apparatus but subsequently fails to arrive at the cell surface and become phosphorylated. Cell type-specific differences in the rate of MHC-I transport through the secretory pathway correlate with responsiveness to Nef and co-precipitation of adaptor protein 1 with the Nef.MHC-I complex. We propose that the assembly of a Nef.MHC-I.adaptor protein 1 complex early in the secretory pathway is important for Nef activity.     

INSL5 is a high affinity specific agonist for GPCR142 (GPR100)

Insulin-like peptide 5 (INSL5) is a peptide that belongs to the relaxin/insulin family, and its receptor has not been identified. In this report, we demonstrate that INSL5 is a specific agonist for GPCR142. Human INSL5 displaces the binding of (125)I-relaxin-3 to GPCR142 with a high affinity (K(i) = 1.5 nM). In a saturation binding assay, (125)I-INSL5 binds GPCR142 with a K(d) value of 2.5 nM. In functional guanosine (gamma-thio)-triphosphate binding and cAMP accumulation assays, INSL5 potently activates GPCR142 with EC(50) values of 1.3 and 1.2 nM, respectively. In addition, INSL5 stimulates Ca(2+) mobilization in HEK293 cells expressing GPCR142 and G alpha(16). Overall, INSL5 behaves as an agonist for GPCR142 similar to relaxin-3. However, unlike relaxin-3, which is also a potent agonist for GPCR135 and LGR7, INSL5 does not activate either GPCR135 or LGR7. INSL5 inhibits (125)I-relaxin-3 binding to GPCR135 with a low potency (K(i) = 500 nM). A functional assay shows that INSL5 (1 microm) is a weak antagonist for GPCR135. In addition, INSL5 (up to 1 microm) shows no affinity or activity at LGR7 or LGR8 either in a binding assay or a bio-functional assay. Previously, we have demonstrated that GPCR142 mRNA is expressed in peripheral tissues, particularly in the colon. Here we show that INSL5 mRNA is expressed in many peripheral tissues, similar to GPCR142. The high affinity interaction between INSL5 and GPCR142 coupled with their co-evolution and partially overlapping tissue expression patterns strongly suggest that INSL5 is an endogenous ligand for GPCR142.