פרסומים

MAIN CONCLUSION: A silicon transporter homolog was upregulated by Si fertilization and drought in potato roots and leaves. High Si in tuber skin resulted in anatomical and compositional changes suggesting delayed skin maturation. Silicon (Si) fertilization has beneficial effects on plant resistance to biotic and abiotic stresses. Potatoes, low Si accumulators, are susceptible to yield loss due to suboptimal growth conditions; thus Si fertilization may contribute to crop improvement. The effect of Si fertilization on transcript levels of putative transporters, Si uptake and tuber quality was studied in potatoes grown in a glasshouse and fertilized with sodium silicate, under normal and drought-stress conditions. Anatomical studies and Raman spectroscopic analyses of tuber skin were conducted. A putative transporter, StLsi1, with conserved amino acid domains for Si transport, was isolated. The StLsi1 transcript was detected in roots and leaves and its level increased twofold following Si fertilization, and about fivefold in leaves upon Si × drought interaction. Nevertheless, increased Si accumulation was detected only in tuber peel of Si-fertilized plants--probably due to passive movement of Si from the soil solution--where it modified skin cell morphology and cell-wall composition. Compared to controls, skin cell area was greater, suberin biosynthetic genes were upregulated and skin cell walls were enriched with oxidized aromatic moieties suggesting enhanced lignification and suberization. The accumulating data suggest delayed tuber skin maturation following Si fertilization. Despite StLsi1 upregulation, low accumulation of Si in roots and leaves may result from low transport activity. Study of Si metabolism in potato, a major staple food, would contribute to the improvement of other low Si crops to ensure food security under changing climate.

Sex chromosomes pose an inherent genetic imbalance between genders. In mammals, one of the female’s X-chromosomes undergoes inactivation (Xi). Indirect measurements estimate that about 20% of Xi genes completely or partially escape inactivation. The identity of these escapee genes and their propensity to escape inactivation remain unsolved. A direct method for identifying escapees was applied by quantifying differential allelic expression from single cells. RNA-Seq fragments were assigned to informative SNPs which were labeled by the appropriate parental haplotype. This method was applied for measuring allelic specific expression from Chromosome-X (ChrX) and an autosomal chromosome as a control. We applied the protocol for measuring biallelic expression from ChrX to 104 primary fibroblasts. Out of 215 genes that were considered, only 13 genes (6%) were associated with biallelic expression. The sensitivity of escapees' identification was increased by combining SNP mapping for parental diploid genomes together with RNA-Seq from clonal single cells (25 lymphoblasts). Using complementary protocols, referred to as strict and relaxed, we confidently identified 25 and 31escapee genes, respectively. When pooled versions of 30 and 100 cells were used, <50% of these genes were revealed. We assessed the generality of our protocols in view of an escapee catalog compiled from indirect methods. The overlap between the escapee catalog and the genes’ list from this study is statistically significant (P-value of E-07). We conclude that single cells’ expression data are instrumental for studying X-inactivation with an improved sensitivity. Finally, our results support the emerging notion of the non-deterministic nature of genes that escape X-chromosome inactivation.

Peptide nucleic acid bis-quinoline conjugates are reported as attractive far-red emitting probes that detect mutated mRNA in living cells at SNP resolution.

Long RNA molecules are at the core of gene regulation across all kingdoms of life, while also serving as genomes in RNA viruses. Few studies have addressed the basic physical properties of long single-stranded RNAs. Long RNAs with non repeating sequences usually adopt highly ramified secondary structures and are better described as branched polymers. To test whether a branched polymer model can estimate the overall sizes of large RNAs, we employed fluorescence correlation spectroscopy to examine the hydrodynamic radii of a broad spectrum of biologically important RNAs, ranging from viral genomes to long noncoding regulatory RNAs. The relative sizes of long RNAs measured at low ionic strength correspond well to those predicted by two theoretical approaches that treat the effective branching associated with secondary structure formation one employing the Kramers theorem for calculating radii of gyration, and the other featuring the metric of maximum ladder distance. Upon addition of multivalent cations, most RNAs are found to be compacted as compared with their original, low ionic-strength sizes. These results suggest that sizes of long RNA molecules are determined by the branching pattern of their secondary structures. We also experimentally validate the proposed computational approaches for estimating hydrodynamic radii of single stranded RNAs, which use generic RNA structure prediction tools and thus can be universally applied to a wide range of long RNAs. http://www.sciencedirect.com/science/article/pii/S0006349516309419

BACKGROUND: Establishing smoke-free environments is a major component of tobacco control policy. The introduction of a smoke-free policy in medical campuses may serve as a role model for other educational and health institutions but little has been published about their prevalence or impact. In 2012, the Faculty of Medicine at Hebrew University-Hadassah in Jerusalem, Israel launched a smoke-free Medical Campus initiative. This study examined smoking behaviours, cigarette smoke exposure and attitudes towards the smoke-free campus policy among students and employees. METHODS: Using a self-administered questionnaire, data was collected from medical, dental and pharmacy students, as well as employees of the school of pharmacy. We approached the entire target population in 2013 (N = 449), with a response rate of 72.5 % (N = 313). RESULTS: The rate of smoking was 8.3 % (95 % CI 5.5-11.9 %). Most participants reported daily exposure or exposure several times a week to cigarette smoke (65.8 %). Overall, 98.0 % had reported seeing people smoke in open campus areas and 27.2 % indoors. Most participants supported the smoking ban inside buildings (94.2 %) but fewer supported (40.8 %) a complete ban of smoking throughout the campus, including outside areas. Only 18.4 % agreed that a policy prohibiting smoking was unfair to smokers. A multivariable analysis showed that support for a complete ban on smoking on campus was higher among non-smokers than for smokers (OR = 9.5, 95 % CI 2.2-31.5, p = 0.02). CONCLUSIONS: The smoke-free policy does not have total compliance, despite the strong support among both students and employees for a smoke-free medical campus. The data collected will assist policy makers move towards a total smoke-free medical campus and will aid tobacco control efforts in Israel and other countries.