Selective loss of innate CD4(+) V alpha 24 natural killer T cells in human immunodeficiency virus infection

V alpha 24 natural killer T (NKT) cells are innate immune cells involved in regulation of immune tolerance, autoimmunity, and tumor immunity. However, the effect of human immunodeficiency virus type 1 (HIV-1) infection on these cells is unknown. Here, we report that the V alpha 24 NKT cells can be subdivided into CD4(+) or CD4(-) subsets that differ in their expression of the homing receptors CD62L and CD11a. Furthermore, both CD4(+) and CD4(-) NKT cells frequently express both CXCR4 and CCR5 HIV coreceptors. We find that the numbers of NKT cells are reduced in HIV-infected subjects with uncontrolled viremia and marked CD4(+) T-cell depletion. The number of CD4(+) NKT cells is inversely correlated with HIV load, indicating depletion of this subset. In contrast, CD4(-) NKT-cell numbers are unaffected in subjects with high viral loads. HIV infection experiments in vitro show preferential depletion of CD4(+) NKT cells relative to regular CD4(+) T cells, in particular with virus that uses the CCR5 coreceptor. Thus, HIV infection causes a selective loss of CD4(+) lymph node homing (CD62L(+)) NKT cells, with consequent skewing of the NKT-cell compartment to a predominantly CD4(-) CD62L(-) phenotype. These data indicate that the key immunoregulatory NKT-cell compartment is compromised in HIV-1-infected patients.     

Temperature trends and recent decline in body size of the stone marten Martes foina in Denmark

We studied a sample of 131 skulls of the stone marten Martes foina that were collected in Denmark between 1858 and 1999. Data were available for 37 years, but collection effort was not uniform throughout the study period and annual sample size varied between 1 and 27. We used principal component analysis (PCA) to combine the information of four skull measurements into a single variable (PC1). PC1 was then corrected for factors that significantly affected it (sex and longitude), and residual PC1 was used for further analysis in which we calculated trends in PC1 values during the study period. During the study period there was an increase in mean annual temperature in Denmark, but this increase was not continuous, as there was slight decrease in temperature between 1947 and 1965.We found that skull size (and by implication body size) of the stone marten in Denmark had two periods of decrease and these two periods coincide with the periods of increase in mean annual temperature. These results may indicate that body size of the stone marten is sensitive to the change in ambient temperature, either due to a change in food availability that was caused by the increase in temperature, or decreased its size in accordance with Bergmann's rule.     

Soluble minerals in chemical evolution

The adsorption of 5-AMP onto solid CaSO₄ · 2H₂O was studied in a saturated suspension as a function of pH and electrolyte concentration. The adsorption is pH-dependent and is directly correlated with the charge on the 5-AMP molecule which is determined by the state of protonation of the N-1 nitrogen of the purine ring and the phosphate oxygens. It is proposed that the binding that occurs between the nucleotide and the salt is electrostatic in nature. The adsorption decreases with increasing ionic strength of the solution which means that in a fluctuating environment of wetting and drying cycles, a biomolecule similar to 5-AMP could be expected to desorb during the drying phase. The results indicate that CaSO₄ · 2H₂O can serve as a concentrating surface for biomolecules. The significance of this is discussed with regard to the possible role of soluble minerals and their surfaces in a geochemical model consistent with the evolution of the Earth and the origin of life.     

Highly efficient de novo mutant identification in a Sorghum bicolor TILLING population using the ComSeq approach

Screening large populations for carriers of known or de novo rare single nucleotide polymorphisms (SNPs) is required both in Targeting induced local lesions in genomes (TILLING) experiments in plants and in screening of human populations. We previously suggested an approach that combines the mathematical field of compressed sensing with next‐generation sequencing to allow such large‐scale screening. Based on pooled measurements, this method identifies multiple carriers of heterozygous or homozygous rare alleles while using only a small fraction of resources. Its rigorous mathematical foundations allow scalable and robust detection, and provide error correction and resilience to experimental noise. Here we present a large‐scale experimental demonstration of our computational approach, in which we targeted a TILLING population of 1024 Sorghum bicolor lines to detect carriers of de novo SNPs whose frequency was less than 0.1%, using only 48 pools. Subsequent validation confirmed that all detected lines were indeed carriers of the predicted mutations. This novel approach provides a highly cost‐effective and robust tool for biologists and breeders to allow identification of novel alleles and subsequent functional analysis.     

Characterization of coding synonymous and non-synonymous variants in ADAMTS13 using ex vivo and in silico approaches

Synonymous variations, which are defined as codon substitutions that do not change the encoded amino acid, were previously thought to have no effect on the properties of the synthesized protein(s). However, mounting evidence shows that these "silent" variations can have a significant impact on protein expression and function and should no longer be considered "silent". Here, the effects of six synonymous and six non-synonymous variations, previously found in the gene of ADAMTS13, the von Willebrand Factor (VWF) cleaving hemostatic protease, have been investigated using a variety of approaches. The ADAMTS13 mRNA and protein expression levels, as well as the conformation and activity of the variants have been compared to that of wild-type ADAMTS13. Interestingly, not only the non-synonymous variants but also the synonymous variants have been found to change the protein expression levels, conformation and function. Bioinformatic analysis of ADAMTS13 mRNA structure, amino acid conservation and codon usage allowed us to establish correlations between mRNA stability, RSCU, and intracellular protein expression. This study demonstrates that variants and more specifically, synonymous variants can have a substantial and definite effect on ADAMTS13 function and that bioinformatic analysis may allow development of predictive tools to identify variants that will have significant effects on the encoded protein.     

Dual‐specificity tyrosine phosphorylation‐regulated kinase 2 regulates osteoclast fusion in a cell heterotypic manner

Monocyte fusion into osteoclasts, bone resorbing cells, plays a key role in bone remodeling and homeostasis; therefore, aberrant cell fusion may be involved in a variety of debilitating bone diseases. Research in the last decade has led to the discovery of genes that regulate osteoclast fusion, but the basic molecular and cellular regulatory mechanisms underlying the fusion process are not completely understood. Here, we reveal a role for Dyrk2 in osteoclast fusion. We demonstrate that Dyrk2 down regulation promotes osteoclast fusion, whereas its overexpression inhibits fusion. Moreover, Dyrk2 also promotes the fusion of foreign‐body giant cells, indicating that Dyrk2 plays a more general role in cell fusion. In an earlier study, we showed that fusion is a cell heterotypic process initiated by fusion‐founder cells that fuse to fusion‐follower cells, the latter of which are unable to initiate fusion. Here, we show that Dyrk2 limits the expansion of multinucleated founder cells through the suppression of the fusion competency of follower cells.     

Combinatorial and Computational Approaches to Identify Interactions of Macrophage Colony-stimulating Factor (M-CSF) and Its Receptor c-FMS

The molecular interactions between macrophage colony-stimulating factor (M-CSF) and the tyrosine kinase receptor c-FMS play a key role in the immune response, bone metabolism, and the development of some cancers. Because no x-ray structure is available for the human M-CSF·c-FMS complex, the binding epitope for this complex is largely unknown. Our goal was to identify the residues that are essential for binding of the human M-CSF to c-FMS. For this purpose, we used a yeast surface display (YSD) approach. We expressed a combinatorial library of monomeric M-CSF (M-CSF_M) single mutants and screened this library to isolate variants with reduced affinity for c-FMS using FACS. Sequencing yielded a number of single M-CSF_M variants with mutations both in the direct binding interface and distant from the binding site. In addition, we used computational modeling to map the identified mutations onto the M-CSF_M structure and to classify the mutations into three groups as follows: those that significantly decrease protein stability; those that destroy favorable intermolecular interactions; and those that decrease affinity through allosteric effects. To validate the YSD and computational data, M-CSF_M and three variants were produced as soluble proteins; their affinity and structure were analyzed; and very good correlations with both YSD data and computational predictions were obtained. By identifying the M-CSF_M residues critical for M-CSF·c-FMS interactions, we have laid down the basis for a deeper understanding of the M-CSF·c-FMS signaling mechanism and for the development of target-specific therapeutic agents with the ability to sterically occlude the M-CSF·c-FMS binding interface.     

The CD85J/leukocyte inhibitory receptor-1 distinguishes between conformed and beta 2-microglobulin-free HLA-G molecules

For a proper development of the placenta, maternal NK cells should not attack the fetal extravillous cytotrophoblast cells. This inhibition of maternal NK cells is partially mediated via the nonclassical MHC class I molecule HLA-G. Recently, we demonstrated that HLA-G forms disulfide-linked high molecular complexes on the surface of transfected cells. In the present study, we demonstrate that HLA-G must associate with beta(2)m for its interaction with CD85J/leukocyte Ig-like receptor-1 (LIR-1). Although HLA-G free H chain complexes are expressed on the surface, they are not recognized and possibly interfere with CD85J/LIR-1 and HLA-G interaction. The formation of these complexes on the cell surface might represent a novel mechanism developed specifically by the HLA-G protein aimed to control the efficiency of the CD85J/LIR-1-mediated inhibition. We also show that endogenous HLA-G complexes are expressed on the cell surface. These findings provide novel insights into the delicate interaction between extravillous cytotrophoblast cells and NK cells in the decidua.     

In Vivo 7T MRI of the Non-Human Primate Brainstem

Structural brain imaging provides a critical framework for performing stereotactic and intraoperative MRI-guided surgical procedures, with procedural efficacy often dependent upon visualization of the target with which to operate. Here, we describe tools for in vivo, subject-specific visualization and demarcation of regions within the brainstem. High-field 7T susceptibility-weighted imaging and diffusion-weighted imaging of the brain were collected using a customized head coil from eight rhesus macaques. Fiber tracts including the superior cerebellar peduncle, medial lemniscus, and lateral lemniscus were identified using high-resolution probabilistic diffusion tractography, which resulted in three-dimensional fiber tract reconstructions that were comparable to those extracted from sequential application of a two-dimensional nonlinear brain atlas warping algorithm. In the susceptibility-weighted imaging, white matter tracts within the brainstem were also identified as hypointense regions, and the degree of hypointensity was age-dependent. This combination of imaging modalities also enabled identifying the location and extent of several brainstem nuclei, including the periaqueductal gray, pedunculopontine nucleus, and inferior colliculus. These clinically-relevant high-field imaging approaches have potential to enable more accurate and comprehensive subject-specific visualization of the brainstem and to ultimately improve patient-specific neurosurgical targeting procedures, including deep brain stimulation lead implantation.