Response of lake phytoplankton communities to in situ manipulations of light intensity and colour

Phytoplankton preferences for light intensity and colour weredetermined in field experiments using coloured plexiglass cubessuspended at different depths in Heney Lake, Québec.Diatoms and green algae favoured intensities greater than 1%I_o (surface irradiance) contrary to dinoflagellates and otherflagellates that preferred lower intensity. Red radiation usuallyincreased the relative proportion of blue-greens, diatoms andgreen algae, whereas it reduced that of dinoflageilates. Wepropose that differential utilization of the light gradientallows certain phytoplankton taxa to partition the water column,thereby reducing potential competition. This is supported bythe general agreement between our findings and the known depthdistribution of algae in lakes.     

Quantitative aspects of RNA synthesis in normal and lithium-treated embryos ofXenopus laevis

Summary The treatment ofXenopus early embryos with lithium chloride produces exogastruale — embryos which fail to gastrulate normally and in which the rates of cell division are reduced. In the present study estimations of incorporations of (5-³H) uridine and the specific activities of the 5-ribonucleotide precursor pools showed that exogastrulae have higher rates of RNA synthesis per cell than control neurulae. Sub-cellular fractionations showed that a greater proportion of labelled RNA was retained in the nuclei of exogastrulae than of neurulae, while neurulae showed a greater incorporation into polysomes.     

Interspersion of sequences in avian myeloblastosis virus rna that rapidly hybridize with leukemic chicken cell DNA.

Liquid hybridization of progressively smaller fragments (35S, 27S, 15.5S, 12.5S, and 8S) of poly(A)-selected avian myeloblastosis virus RNA with excess DNA from leukemic chicken myeloblasts revealed that all sizes of RNA contained sequences complementary to both slowly and rapidly hybridizing cellular DNA sequences. Apparently, the RNA sequences which hybridize rapidly with excesses of cellular DNA are not restricted to any one region of the avian myeloblastosis virus 35S RNA. Instead, they appear to be randomly distributed over the entire 35S avian myeloblastosis virus RNA molecule with some positioned within 200 nucleotides of the poly(A) tract at the 3' end of the RNA.     

Hybrid Cluster Proteins and Flavodiiron Proteins Afford Protection to Desulfovibrio vulgaris upon Macrophage Infection

Desulfovibrio species are Gram-negative anaerobic sulfate-reducing bacteria that colonize the human gut. Recently, Desulfovibrio spp. have been implicated in gastrointestinal diseases and shown to stimulate the epithelial immune response, leading to increased production of inflammatory cytokines by macrophages. Activated macrophages are key cells of the immune system that impose nitrosative stress during phagocytosis. Hence, we have analyzed the in vitro and in vivo responses of Desulfovibrio vulgaris Hildenborough to nitric oxide (NO) and the role of the hybrid cluster proteins (HCP1 and HCP2) and rubredoxin oxygen oxidoreductases (ROO1 and ROO2) in NO protection. Among the four genes, hcp2 was the gene most highly induced by NO, and the hcp2 transposon mutant exhibited the lowest viability under conditions of NO stress. Studies in murine macrophages revealed that D. vulgaris survives incubation with these phagocytes and triggers NO production at levels similar to those stimulated by the cytokine gamma interferon (IFN-γ). Furthermore, D. vulgaris hcp and roo mutants exhibited reduced viability when incubated with macrophages, revealing that these gene products contribute to the survival of D. vulgaris during macrophage infection.     

A computational framework for modeling cell–matrix interactions in soft biological tissues

Biomechanics and Modeling in Mechanobiology - Living soft tissues appear to promote the development and maintenance of a preferred mechanical state within a defined tolerance around a so-called set...     

Isolation and Characterisation of a Recombinant Antibody Fragment That Binds NCAM1-Expressing Intervertebral Disc Cells

Degeneration of the intervertebral discs (IVD) is a leading cause of neck and low back pain. Degeneration begins in the central nucleus pulposus region, leading to loss of IVD osmotic properties. Regeneration approaches include administration of matrix-mimicking scaffolds, cells and/or therapeutic factors. Cell-targeting strategies are likely to improve delivery due to the low cell numbers in the IVD. Single-chain antibody fragments (scFvs) that bind IVD cells were isolated for potential delivery of therapeutics to degenerated IVD. The most cell-distal domain of neural cell adhesion molecule 1 (NCAM1) was cloned and expressed in Escherichia coli. Phage display technology was used to isolate a human scFv against the recombinant domain by panning a scFv library on the immobilised protein. The isolated scFv bound cultured rat astrocytes, as well as bovine nucleus pulposus and annulus fibrosus cells in immunocytochemical studies. The scFv also labelled cells in bovine spinal cord and six-month and two-year old bovine IVD sections by immunohistochemistry. Antibody fragments can provide cell-binding moieties at improved cost, time, yield and functionalisation potential over whole antibodies. The described scFv has potential application in delivery of therapeutics to NCAM1-expressing cells in degenerated IVD.     

Function and Regulation of AUTS2, a Gene Implicated in Autism and Human Evolution

Nucleotide changes in the AUTS2 locus, some of which affect only noncoding regions, are associated with autism and other neurological disorders, including attention deficit hyperactivity disorder, epilepsy, dyslexia, motor delay, language delay, visual impairment, microcephaly, and alcohol consumption. In addition, AUTS2 contains the most significantly accelerated genomic region differentiating humans from Neanderthals, which is primarily composed of noncoding variants. However, the function and regulation of this gene remain largely unknown. To characterize auts2 function, we knocked it down in zebrafish, leading to a smaller head size, neuronal reduction, and decreased mobility. To characterize AUTS2 regulatory elements, we tested sequences for enhancer activity in zebrafish and mice. We identified 23 functional zebrafish enhancers, 10 of which were active in the brain. Our mouse enhancer assays characterized three mouse brain enhancers that overlap an ASD–associated deletion and four mouse enhancers that reside in regions implicated in human evolution, two of which are active in the brain. Combined, our results show that AUTS2 is important for neurodevelopment and expose candidate enhancer sequences in which nucleotide variation could lead to neurological disease and human-specific traits.     

Different value of coronary calcium score to predict obstructive coronary artery disease in patients with and without moderate chronic kidney disease

Purpose

The coronary calcium score (CCS) predicts significant coronary artery disease (CAD) in the general population. While moderate chronic kidney disease (CKD) is associated with high CCS, the use of CCS to predict significant CAD in these patients is unknown.

Methods

A total of 704 patients underwent computed tomography coronary angiography for the assessment of CCS and CAD. Sixty-nine (10 %) patients had moderate CKD, defined by an estimated glomerular filtration rate (eGFR) between 30 and 59 mL/min/1.73m², and the remaining patients were considered to be without significant CKD (eGFR?≥?60 mL/min/1.73m²).

Results

Patients with moderate CKD were older, had a higher CCS, and a higher prevalence of obstructive CAD than patients without significant CKD. Receiver-operator curve analysis showed that CCS predicted the presence of obstructive CAD in both patients with moderate CKD and those without significant CKD. In patients with moderate CKD, the optimal cut-off value of CCS to diagnose obstructive CAD was 140 (sensitivity 73 % and specificity of 70 %), and is 2.8 fold higher than in patients without significant CKD (cut-off value?=?50; sensitivity 75 % and specificity 75 %).

Conclusion

The present results demonstrate that CCS can predict obstructive CAD in patients with moderate CKD, although the optimal cut-off value is higher than in patients without significant CKD.