Ultraviolet polarisation sensitivity in the stomatopod crustacean Odontodactylus scyllarus

The ommatidia of crustacean eyes typically contain two classes of photoreceptors with orthogonally oriented microvilli. These receptors provide the basis for two-channel polarisation vision in the blue–green spectrum. The retinae of gonodactyloid stomatopod crustaceans possess a great variety of structural specialisations for elaborate polarisation vision. One type of specialisation is found in the small, distally placed R8 cells within the two most ventral rows of the mid-band. These ultraviolet-sensitive photoreceptors produce parallel microvilli, a feature suggestive for polarisation-sensitive photoreceptors. Here, we show by means of intracellular recordings combined with dye-injections that in the gonodactyloid species Odontodactylus scyllarus, the R8 cells of mid-band rows 5 and 6 are sensitive to linear polarised ultraviolet light. We show that mid-band row 5 R8 cells respond maximally to light with an e-vector oriented parallel to the mid-band, whereas mid-band row 6 R8 cells respond maximally to light with an e-vector oriented perpendicular to the mid-band. This orthogonal arrangement of ultraviolet-sensitive receptor cells could support ultraviolet polarisation vision. R8 cells of rows 5 and 6 are known to act as quarter-wave retarders around 500 nm and thus are the first photoreceptor type described with a potential dual role in polarisation vision

Low penetrance of retinoblastoma for p.V654L mutation of the RB1 gene

<p>Abstract</p> <p>Background</p> <p>Retinoblastoma is caused by compound heterozygosity or homozygosity of retinoblastoma gene (<it>RB1</it>) mutations. In germline retinoblastoma, mutations in the <it>RB1 </it>gene predispose individuals to increased cancer risks during development. These mutations segregate as autosomal dominant traits with high penetrance (90%).</p> <p>Methods</p> <p>We screened 30 family members from one family using high resolution melting assay and DNA direct sequencing for mutations in the <it>RB1 </it>gene. We evaluate the phenotype and penetrance of germline mutations of the <it>RB1 </it>gene in a large Taiwanese family.</p> <p>Results</p> <p>The molecular analysis and clinical details of this family showed phenotypic variability associated with the p.V654L mutation in exon 19 of the <it>RB1 </it>gene in 11 family members. The phenotype varied from asymptomatic to presence of a unilateral tumor. Only four individuals (2 males and 2 females) developed unilateral retinoblastoma, which resulted in calculated low penetrance of 36% (4/11). The four individuals with retinoblastoma were diagnosed before the age of three years. None of their relatives exhibited variable severity or bilateral retinoblastoma.</p> <p>Conclusions</p> <p>The diseased-eye ratio for this family was 0.36, which is lower than current estimates. This suggests that the <it>RB1 </it>p.V654L mutation is a typical mutation associated with low penetrance.</p

Search for a Technicolor omega_T Particle in Events with a Photon and a b-quark Jet at CDF

If the Technicolor omega_T particle exists, a likely decay mode is omega_T -> gamma pi_T, followed by pi_T -> bb-bar, yielding the signature gamma bb-bar. We have searched 85 pb^-1 of data collected by the CDF experiment at the Fermilab Tevatron for events with a photon and two jets, where one of the jets must contain a secondary vertex implying the presence of a b quark. We find no excess of events above standard model expectations. We express the result of an exclusion region in the M_omega_T - M_pi_T mass plane.Comment: 14 pages, 2 figures. Available from the CDF server (PS with figs): http://www-cdf.fnal.gov/physics/pub98/cdf4674_omega_t_prl_4.ps FERMILAB-PUB-98/321-

Fibroblast Growth Factor-2 Primes Human Mesenchymal Stem Cells for Enhanced Chondrogenesis

Human mesenchymal stem cells (hMSCs) are multipotent cells capable of differentiating into a variety of mature cell types, including osteoblasts, adipocytes and chondrocytes. It has previously been shown that, when expanded in medium supplemented with fibroblast growth factor-2 (FGF-2), hMSCs show enhanced chondrogenesis (CG). Previous work concluded that the enhancement of CG could be attributed to the selection of a cell subpopulation with inherent chondrogenic potential. In this study, we show that FGF-2 pretreatment actually primed hMSCs to undergo enhanced CG by increasing basal Sox9 protein levels. Our results show that Sox9 protein levels were elevated within 30 minutes of exposure to FGF-2 and progressively increased with longer exposures. Further, we show using flow cytometry that FGF-2 increased Sox9 protein levels per cell in proliferating and non-proliferating hMSCs, strongly suggesting that FGF-2 primes hMSCs for subsequent CG by regulating Sox9. Indeed, when hMSCs were exposed to FGF-2 for 2 hours and subsequently differentiated into the chondrogenic lineage using pellet culture, phosphorylated-Sox9 (pSox9) protein levels became elevated and ultimately resulted in an enhancement of CG. However, small interfering RNA (siRNA)-mediated knockdown of Sox9 during hMSC expansion was unable to negate the prochondrogenic effects of FGF-2, suggesting that the FGF-2-mediated enhancement of hMSC CG is only partly regulated through Sox9. Our findings provide new insights into the mechanism by which FGF-2 regulates predifferentiation hMSCs to undergo enhanced CG

The Risk of Stroke after Percutaneous Vertebroplasty for Osteoporosis: A Population-Based Cohort Study

PURPOSE: To investigate the incidence and risk of stroke after percutaneous vertebroplasty in patients with osteoporosis. METHODS: A group of 334 patients with osteoporosis, and who underwent percutaneous vertebroplasty during the study period, was compared to 1,655 age-, sex- and propensity score-matched patients who did not undergo vertebroplasty. All demographic covariates and co-morbidities were deliberately matched between the two groups to avoid selection bias. Every subject was followed-up for up to five years for stroke. Adjustments using a Cox regression model and Kaplan-Meier analyses were conducted. RESULTS: A total of 1,989 osteoporotic patients were followed up for 3,760.13 person-years. Overall, the incidence rates of any stroke, hemorrhagic stroke and ischemic stroke were 22.6, 4.2 and 19.6 per 1,000 person-years, respectively. Patients who underwent vertebroplasty were not more likely to have any stroke (crude hazard ratio = 1.13, p = 0.693), hemorrhagic stroke (HR = 2.21, p = 0.170), or ischemic stroke (HR = 0.96, p = 0.90). After adjusting for demographics, co-morbidities and medications, the vertebroplasty group had no significant difference with the comparison group in terms of any, hemorrhagic and ischemic strokes (adjusted HR = 1.22, 3.17, and 0.96, p = 0.518, 0.055, and 0.91, respectively). CONCLUSIONS: Osteoporotic patients who undergo percutaneous vertebroplasty are not at higher risk of any stroke in the next five years after the procedure

Metabolic Versatility and Antibacterial Metabolite Biosynthesis Are Distinguishing Genomic Features of the Fire Blight Antagonist Pantoea vagans C9-1

Smits THM, Rezzonico F, Kamber T, et al. Metabolic Versatility and Antibacterial Metabolite Biosynthesis Are Distinguishing Genomic Features of the Fire Blight Antagonist Pantoea vagans C9-1. PLoS ONE. 2011;6(7): e22247.Background: Pantoea vagans is a commercialized biological control agent used against the pome fruit bacterial disease fire blight, caused by Erwinia amylovora. Compared to other biocontrol agents, relatively little is currently known regarding Pantoea genetics. Better understanding of antagonist mechanisms of action and ecological fitness is critical to improving efficacy. Principal Findings: Genome analysis indicated two major factors contribute to biocontrol activity: competition for limiting substrates and antibacterial metabolite production. Pathways for utilization of a broad diversity of sugars and acquisition of iron were identified. Metabolism of sorbitol by P. vagans C9-1 may be a major metabolic feature in biocontrol of fire blight. Biosynthetic genes for the antibacterial peptide pantocin A were found on a chromosomal 28-kb genomic island, and for dapdiamide E on the plasmid pPag2. There was no evidence of potential virulence factors that could enable an animal or phytopathogenic lifestyle and no indication of any genetic-based biosafety risk in the antagonist. Conclusions: Identifying key determinants contributing to disease suppression allows the development of procedures to follow their expression in planta and the genome sequence contributes to rationale risk assessment regarding the use of the biocontrol strain in agricultural systems

A Genome-Wide Characterization of MicroRNA Genes in Maize

MicroRNAs (miRNAs) are small, non-coding RNAs that play essential roles in plant growth, development, and stress response. We conducted a genome-wide survey of maize miRNA genes, characterizing their structure, expression, and evolution. Computational approaches based on homology and secondary structure modeling identified 150 high-confidence genes within 26 miRNA families. For 25 families, expression was verified by deep-sequencing of small RNA libraries that were prepared from an assortment of maize tissues. PCR–RACE amplification of 68 miRNA transcript precursors, representing 18 families conserved across several plant species, showed that splice variation and the use of alternative transcriptional start and stop sites is common within this class of genes. Comparison of sequence variation data from diverse maize inbred lines versus teosinte accessions suggest that the mature miRNAs are under strong purifying selection while the flanking sequences evolve equivalently to other genes. Since maize is derived from an ancient tetraploid, the effect of whole-genome duplication on miRNA evolution was examined. We found that, like protein-coding genes, duplicated miRNA genes underwent extensive gene-loss, with ∼35% of ancestral sites retained as duplicate homoeologous miRNA genes. This number is higher than that observed with protein-coding genes. A search for putative miRNA targets indicated bias towards genes in regulatory and metabolic pathways. As maize is one of the principal models for plant growth and development, this study will serve as a foundation for future research into the functional roles of miRNA genes