Fine-scale genetic structure in populations of the Chagas’ disease vector Triatoma infestans (Hemiptera, Reduvidae)

Fine scale patterns of genetic structure and dispersal in Triatoma infestans populations from Argentina was analysed. A total of 314 insects from 22 domestic and peridomestic sites from the locality of San Martín (Capayán department, Catamarca province) were typed for 10 polymorphic microsatellite loci. The results confirm subdivision of T. infestans populations with restricted dispersal among sampling sites and suggest inbreeding and/or stratification within the different domestic and peridomestic structures. Spatial correlation analysis showed that the scale of structuring is approximately of 400 m, indicating that active dispersal would occur within this distance range. It was detected difference in scale of structuring among sexes, with females dispersing over greater distances than males. This study suggests that insecticide treatment and surveillance should be extended within a radius of 400 m around the infested area, which would help to reduce the probability of reinfestation by covering an area of active dispersal. The inferences made from fine-scale spatial genetic structure analyses of T. infestans populations has demonstrated to be important for community-wide control programs, providing a complementary approach to help improve vector control strategies.     

Notes on Scleroderma,Puff balls and Geastrum of Azad Jammu and Kashmir,Pakistan

Six species of mushrooms allied to the Family Sclerodermataceae, Lycoperdaceae and Geastraceae have been described for the first time from Azad Jammu and Kashmir. These are Scleroderma aurantium, Calvatia verrucosia sp. nov., Lycoperdon pedicellaton sp. nov. L. sphaericon sp. nov., L. echinulaton sp. nov., and Geastrum heptaplex sp. nov.     

The role of light quality of photoperiodic lighting on photosynthesis,flowering and metabolic profiling in Ranunculus asiaticus L.

Photoperiodic light quality affects flowering of long day plants, by influencing the phytochrome photoequilibria (PPE) at plant level; however, the most effective light spectrum to promote flowering is still unknown for most of the flower crops. We evaluated the influence of light spectrum of three light sources, with different induced PPE, on photosynthesis, metabolic profiling, plant growth and flowering in two hybrids of Ranunculus asiaticus L., MBO (early flowering) and MDR (medium earliness). Three photoperiodic treatments were compared to natural day length (NL): white fluorescent light (PPE 0.84), light emitting diodes (LEDs) with red:far red (R:FR) light at 3:1 ratio (PPE, 0.84) and LEDs with R:FR light at 1:3 ratio (PPE 0.63). Under natural light, net photosynthesis was higher in MDR than in MBO, while photochemistry was similar in the hybrids. Compared to NL, photoperiodic treatments did not affect net photosynthesis, while they promoted the quantum yield of PSII and reduced the non-photochemical quenching. Under NL, plant growth was greater in MBO, while flowering started earlier in MDR and flowers characteristics were similar in the hybrids. Despite the greater sensitivity of MDR plants in terms of metabolism, photoperiodic lighting improved plant growth and reduced the flowering time only in MBO, with a stronger effect under R:FR 3:1 light. MDR plants were characterized by higher soluble sugars, polyphenols, photosynthetic pigments and proteins, while MBO plants by higher starch and amino acid content. The morphological effects of photoperiodic light quality and the hybrid-specific response should be taken into account to optimize lighting protocols in commercial farms.     

Homeodomain-interacting protein kinase-2 stabilizes p27(kip1) by its phosphorylation at serine 10 and contributes to cell motility

HIPK2 is a serine/threonine kinase that acts as a coregulator of an increasing number of factors involved in cell survival and proliferation during development and in response to different types of stress. Here we report on a novel target of HIPK2, the cyclin-dependent kinase inhibitor p27(kip1). HIPK2 phosphorylates p27(kip1) in vitro and in vivo at serine 10, an event that accounts for 80% of the total p27(kip1) phosphorylation and plays a crucial role in the stability of the protein. Indeed, HIPK2 depletion by transient or stable RNA interference in tumor cells of different origin was consistently associated with strong reduction of p27(kip1) phosphorylation at serine 10 and of p27(kip1) stability. An initial evaluation of the functional relevance of this HIPK2-mediated regulation of p27(kip1) revealed a contribution to cell motility, rather than to cell proliferation, but only in cells that do not express wild-type p53.     

Low-resolution structure and fluorescence anisotropy analysis of protein tyrosine phosphatase eta catalytic domain

The rat protein tyrosine phosphatase eta, rPTPeta, is a class I "classical" transmembrane RPTP, with an intracellular portion composed of a unique catalytic region. The rPTPeta and the human homolog DEP-1 are downregulated in rat and human neoplastic cells, respectively. However, the malignant phenotype is reverted after exogenous reconstitution of rPTPeta, suggesting that its function restoration could be an important tool for gene therapy of human cancers. Using small-angle x-ray scattering (SAXS) and biophysical techniques, we characterized the intracellular catalytic domain of rat protein tyrosine phosphatase eta (rPTPetaCD) in solution. The protein forms dimers in solution as confirmed by SAXS data analysis. The SAXS data also indicated that rPTPetaCD dimers are elongated and have an average radius of gyration of 2.65 nm and a D(max) of 8.5 nm. To further study the rPTPetaCD conformation in solution, we built rPTPetaCD homology models using as scaffolds the crystallographic structures of RPTPalpha-D1 and RPTPmicro-D1 dimers. These models were, then, superimposed onto ab initio low-resolution SAXS structures. The structural comparisons and sequence alignment analysis of the putative dimerization interfaces provide support to the notion that the rPTPetaCD dimer architecture is more closely related to the crystal structure of autoinhibitory RPTPalpha-D1 dimer than to the dimeric arrangement exemplified by RPTPmicro-D1. Finally, the characterization of rPTPetaCD by fluorescence anisotropy measurements demonstrates that the dimer dissociation is concentration dependent with a dissociation constant of 21.6 +/- 2.0 microM.     

Resequencing the susceptibility gene,ITGAM, identifies two functionally deleterious rare variants in systemic lupus erythematosus cases

Introduction

The majority of the genetic variance of systemic lupus erythematosus (SLE) remains unexplained by the common disease-common variant hypothesis. Rare variants, which are not detectable by genome-wide association studies because of their low frequencies, are predicted to explain part of this ”missing heritability.” However, recent studies identifying rare variants within known disease-susceptibility loci have failed to show genetic associations because of their extremely low frequencies, leading to the questioning of the contribution of rare variants to disease susceptibility. A common (minor allele frequency = 17.4% in cases) nonsynonymous coding variant rs1143679 (R77H) in ITGAM (CD11b), which forms half of the heterodimeric integrin receptor, complement receptor 3 (CR3), is robustly associated with SLE and has been shown to impair CR3-mediated phagocytosis.

Methods

We resequenced ITGAM in 73 SLE cases and identified two previously unidentified, case-specific nonsynonymous variants, F941V and G1145S. Both variants were genotyped in 2,107 and 949 additional SLE cases, respectively, to estimate their frequencies in a disease population. An in vitro model was used to assess the impact of F941V and G1145S, together with two nonsynonymous ITGAM polymorphisms, A858V (rs1143683) and M441T (rs11861251), on CR3-mediated phagocytosis. A paired two-tailed t test was used to compare the phagocytic capabilities of each variant with that of wild-type CR3.

Results

Both rare variants, F941V and G1145S, significantly impair CR3-mediated phagocytosis in an in vitro model (61% reduction, P = 0.006; 26% reduction, P = 0.0232). However, neither of the common variants, M441T and A858V, had an effect on phagocytosis. Neither rare variant was observed again in the genotyping of additional SLE cases, suggesting that there frequencies are extremely low.

Conclusions

Our results add further evidence to the functional importance of ITGAM in SLE pathogenesis through impaired phagocytosis. Additionally, this study provides a new example of the identification of rare variants in common-allele-associated loci, which, because of their extremely low frequencies, are not statistically associated. However, the demonstration of their functional effects adds support to their contribution to disease risk, and questions the current notion of dismissing the contribution of very rare variants on purely statistical analyses.     

Single mRNA molecules demonstrate probabilistic movement in living mammalian cells

Cytoplasmic mRNA movements ultimately determine the spatial distribution of protein synthesis. Although some mRNAs are compartmentalized in cytoplasmic regions, most mRNAs, such as housekeeping mRNAs or the poly-adenylated mRNA population, are believed to be distributed throughout the cytoplasm. The general mechanism by which all mRNAs may move, and how this may be related to localization, is unknown. Here, we report a method to visualize single mRNA molecules in living mammalian cells, and we report that, regardless of any specific cytoplasmic distribution, individual mRNA molecules exhibit rapid and directional movements on microtubules. Importantly, the beta-actin mRNA zipcode increased both the frequency and length of these movements, providing a common mechanistic basis for both localized and nonlocalized mRNAs. Disruption of the cytoskeleton with drugs showed that microtubules and microfilaments are involved in the types of mRNA movements we have observed, which included complete immobility and corralled and nonrestricted diffusion. Individual mRNA molecules switched frequently among these movements, suggesting that mRNAs undergo continuous cycles of anchoring, diffusion, and active transport.