Examination of Water Phase Transitions in Black Spruce by Magnetic Resonance and Magnetic Resonance Imaging

This study examines the phase transitions of water in wood by magnetic resonance and magnetic resonance imaging. The goal was to observe and understand the behavior of water below 0°C in wood. The species studied, black spruce (Picea mariana Mill.), presented one abrupt phase change that occurred at about -3°C, which was attributed to the phase transition of free water. A more diffuse change occurred below -60°C, which was attributed to a phase transition of bound water. A recently developed portable unilateral magnetic resonance instrument is demonstrated as a powerful tool in the study of water in wood. This portable magnet used a bulk spin-spin relaxation time measurement that quantifies observable bound and free water in wood. Imaging was used to verify the unilateral magnetic resonance results and to better understand realistic freeze-thaw behavior of log samples in the field. A ring boundary behavior during the thawing process was observed, and likewise there were differences in the thawing behaviors of heartwood and sapwood samples

Sexual dimorphism in immune response genes as a function of puberty

BACKGROUND: Autoimmune diseases are more prevalent in females than in males, whereas males have higher mortality associated with infectious diseases. To increase our understanding of this sexual dimorphism in the immune system, we sought to identify and characterize inherent differences in immune response programs in the spleens of male and female mice before, during and after puberty. RESULTS: After the onset of puberty, female mice showed a higher expression of adaptive immune response genes, while males had a higher expression of innate immune genes. This result suggested a requirement for sex hormones. Using in vivo and in vitro assays in normal and mutant mouse strains, we found that reverse signaling through FasL was directly influenced by estrogen, with downstream consequences of increased CD8(+ )T cell-derived B cell help (via cytokines) and enhanced immunoglobulin production. CONCLUSION: These results demonstrate that sexual dimorphism in innate and adaptive immune genes is dependent on puberty. This study also revealed that estrogen influences immunoglobulin levels in post-pubertal female mice via the Fas-FasL pathway

The Na+/Ca2+, K+ exchanger NCKX4 is required for efficient cone-mediated vision

Calcium (Ca2+) plays an important role in the function and health of neurons. In vertebrate cone photoreceptors, Ca2+ controls photoresponse sensitivity, kinetics, and light adaptation. Despite the critical role of Ca2+ in supporting the function and survival of cones, the mechanism for its extrusion from cone outer segments is not well understood. Here, we show that the Na+/Ca2+, K+ exchanger NCKX4 is expressed in zebrafish, mouse, and primate cones. Functional analysis of NCKX4-deficient mouse cones revealed that this exchanger is essential for the wide operating range and high temporal resolution of cone-mediated vision. We show that NCKX4 shapes the cone photoresponse together with the cone-specific NCKX2: NCKX4 acts early to limit response amplitude, while NCKX2 acts late to further accelerate response recovery. The regulation of Ca2+ by NCKX4 in cones is a novel mechanism that supports their ability to function as daytime photoreceptors and promotes their survival

Genome-wide association study of pigmentary traits (skin and iris color) in individuals of East Asian ancestry

Background: Currently, there is limited knowledge about the genetics underlying pigmentary traits in East Asian populations. Here, we report the results of the first genome-wide association study of pigmentary traits (skin and iris color) in individuals of East Asian ancestry. Methods: We obtained quantitative skin pigmentation measures (M-index) in the inner upper arm of the participants using a portable reflectometer (N = 305). Quantitative measures of iris color (expressed as L*, a* and b* CIELab coordinates) were extracted from high-resolution iris pictures (N = 342). We also measured the color differences between the pupillary and ciliary regions of the iris (e.g., iris heterochromia). DNA samples were genotyped with Illumina’s Infinium Multi-Ethnic Global Array (MEGA) and imputed using the 1000 Genomes Phase 3 samples as reference haplotypes. Results: For skin pigmentation, we did not observe any genome-wide significant signal. We followed-up in three independent Chinese samples the lead SNPs of five regions showing multiple common markers (minor allele frequency ≥ 5%) with good imputation scores and suggestive evidence of association (p-values < 10−5). One of these markers, rs2373391, which is located in an intron of the ZNF804B gene on chromosome 7, was replicated in one of the Chinese samples (p = 0.003). For iris color, we observed genome-wide signals in the OCA2 region on chromosome 15. This signal is driven by the non-synonymous rs1800414 variant, which explains 11.9%, 10.4% and 6% of the variation observed in the b*, a* and L* coordinates in our sample, respectively. However, the OCA2 region was not associated with iris heterochromia. Discussion: Additional genome-wide association studies in East Asian samples will be necessary to further disentangle the genetic architecture of pigmentary traits in East Asian populations

Individual Oligodendrocytes Have Only a Few Hours in which to Generate New Myelin Sheaths In Vivo

The number of myelin sheaths made by individual oligodendrocytes regulates the extent of myelination, which profoundly affects central nervous system function. It remains unknown when, during their life, individual oligodendrocytes can regulate myelin sheath number in vivo. We show, using live imaging in zebrafish, that oligodendrocytes make new myelin sheaths during a period of just 5 hr, with regulation of sheath number after this time limited to occasional retractions. We also show that activation and reduction of Fyn kinase in oligodendrocytes increases and decreases sheath number per cell, respectively. Interestingly, these oligodendrocytes also generate their new myelin sheaths within the same period, despite having vastly different extents of myelination. Our data demonstrate a restricted time window relative to the lifetime of the individual oligodendrocyte, during which myelin sheath formation occurs and the number of sheaths is determined

NPY moderates the relation between hurricane exposure and generalized anxiety disorder in an epidemiologic sample of hurricane-exposed adults

Background : Neuropeptide Y (NPY) has been found to be anxiolytic in animals and humans. A recent study found NPY expression to be inversely correlated with trait anxiety. We examined whether rs16147, a functional single nucleotide polymorphism in the promoter region of NPY, moderated the relationship between hurricane exposure and risk for generalized anxiety disorder (GAD) in an epidemiologic sample of adults living in areas affected by the 2004 Florida Hurricanes. Methods : Data from this study comes from 616 adults from the 2004 Florida Hurricanes study who returned buccal DNA samples via mail. Selection of participants occurred via random digit-dial procedures. Participants were interviewed via telephone about hurricane exposure and posthurricane GAD symptoms. The outcome measure was DSM-IV GAD diagnosis, assessed via structured interview. Results : Rs16147 in NPY was associated with increased risk of GAD diagnosis under conditions of high hurricane exposure (P<.01). This gene by environment interaction remained significant after adjustment for sex, ancestry (as determined by Bayesian clustering of genotypes), and age. Conclusions : NPY rs16147 modifies risk of postdisaster GAD under conditions of high stressor (hurricane) exposure. This is the first demonstration of gene–environment interaction for this locus. Depression and Anxiety, 2010. © 2009 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69171/1/20648_ftp.pd