The Role of Currents and Waves in the Dispersal of Submersed Angiosperm Seeds and Seedlings

We tested the hypothesis that currents, waves, and sediment grain size affect the dispersal of seeds and seedlings of the submersed angiosperms Ruppia maritima, Potamogeton perfoliatus and Stuckenia pectinata. Seed settling velocities and initiation of motion of seeds and seedlings and distance transported were quantified on four sediment types under a range of currents and waves in a flume. The rapid settling velocities of R. maritima and S. pectinata seeds and the increased settling velocity of P. perfoliatus in currents above 8 cm/second suggest that primary dispersal of these species is localized to the general area colonized by their parents. Once settled within a bed, seeds are exposed to weak currents and waves, and are likely to be subject to sediment deposition which may further limit dispersal. In contrast, in restoration projects, the absence of vegetation is likely to make seeds more vulnerable to grazing and transport, and may contribute to the lack of plant establishment. If seeds germinate without being buried, they are susceptible to secondary dispersal at relatively low current velocities and small wave heights due to the drag exerted on the cotyledon. Sand grains tend to stick to the seed coat and rootlet of P. perfoliatus seedlings, perhaps a mechanism to reduce the chances of being displaced following germination. These data reveal the close links between sediment, water flow, and submersed angiosperm seedling establishment; these parameters should be considered when using seeds for restoration of submersed angiosperms.     

Production of Fusarium solani f. sp. pisi cutinase in Fusarium venenatum A3/5

Fusarium venenatum A3/5 was transformed using the Aspergillus niger expression plasmid, pIGF, in which the coding sequence for the F. solani f. sp. pisi cutinase gene had been inserted in frame, with a KEX2 cleavage site, with the truncated A. niger glucoamylase gene under control of the A. niger glucoamylase promoter. The transformant produced up to 21 U cutinase l⁻¹ in minimal medium containing glucose or starch as the primary carbon source. Glucoamylase (165 U l⁻¹ or 8 mg l⁻¹) was also produced. Both the transformant and the parent strain produced cutinase in medium containing cutin.     

Identification and subcellular localization of paracellin-1 (claudin-16) in human salivary glands

Salivary calcium plays an important role in the pathogenesis of dental caries and the bio-mineralization of dental enamel and exposed dentin. The cellular and molecular basis of calcium secretion by the human salivary glands is, however, poorly understood. Recently a transcellular transport of calcium by the acinus cells has been proposed. In this paper we looked for evidence for paracellular calcium transport by investigating the presence and cellular localization of paracellin-1 (claudin-16) that has been implied in paracellular magnesium and calcium transport in the kidney. At the mRNA level, using RT-PCR with primers of appropriate sequence, paracellin-1 mRNA could be found in human Glandula parotis, Glandula submandibularis, Glandula labialis and Glandula sublingualis samples. In addition, a splice variant was detected in three out of 15 glands consisting of exons one and five of the paracellin gene. In immunohistochemical studies paracellin-1 colocalised in the salivary excretory ducts with the tight junction proteins ZO-1 and occludin suggesting a potential role in paracellular calcium and magnesium transport. In the acini no such colocalisation was observed; paracellin was instead detected at the basal poles of the cells, between cells of the same acinus as well as between cells of neighboring acini. At this location paracellin-1 might act as selectivity filter for the paracellular movement of ions and water during stimulated secretion. Thus, both in the ducts and in the acini a paracellular transport of calcium appears possible. Whether it occurs at all and the extent to which it contributes to the overall salivary calcium secretion remains, however, to be determined.     

Measurement of Physician-Patient Communication—A Systematic Review

Background

Effective communication with health care providers has been found as relevant for physical and psychological health outcomes as well as the patients'' adherence. However, the validity of the findings depends on the quality of the applied measures. This study aimed to provide an overview of measures of physician-patient communication and to evaluate the methodological quality of psychometric studies and the quality of psychometric properties of the identified measures.

Methods

A systematic review was performed to identify psychometrically tested instruments which measure physician-patient communication. The search strategy included three databases (EMBASE, PsycINFO, PubMed), reference and citation tracking and personal knowledge. Studies that report the psychometric properties of physician-patient communication measures were included. Two independent raters assessed the methodological quality of the selected studies with the COSMIN (COnsensus based Standards for the selection of health status Measurement INtruments) checklist. The quality of psychometric properties was evaluated with the quality criteria of Terwee and colleagues.

Results

Data of 25 studies on 20 measures of physician-patient communication were extracted, mainly from primary care samples in Europe and the USA. Included studies reported a median of 3 out of the nine COSMIN criteria. Scores for internal consistency and content validity were mainly fair or poor. Reliability and structural validity were rated mainly of fair quality. Hypothesis testing scored mostly poor. The quality of psychometric properties of measures evaluated with Terwee et al.''s criteria was rated mainly intermediate or positive.

Discussion

This systematic review identified a number of measures of physician-patient communication. However, further psychometric evaluation of the measures is strongly recommended. The application of quality criteria like the COSMIN checklist could improve the methodological quality of psychometric property studies as well as the comparability of the studies'' results.     

Assessment of Trust in Physician: A Systematic Review of Measures

Over the last decades, trust in physician has gained in importance. Studies have shown that trust in physician is associated with positive health behaviors in patients. However, the validity of empirical findings fundamentally depends on the quality of the measures in use. Our aim was to provide an overview of trust in physician measures and to evaluate the methodological quality of the psychometric studies and the quality of psychometric properties of identified measures. We conducted an electronic search in three databases (Medline, EMBASE and PsycInfo). The secondary search strategy included reference and citation tracking of included full texts and consultation of experts in the field. Retrieved records were screened independently by two reviewers. Full texts that reported on testing of psychometric properties of trust in physician measures were included in the review. Study characteristics and psychometric properties were extracted. We evaluated the quality of design, methods and reporting of studies with the COnsensus based Standards for the selection of health status Measurement INstruments (COSMIN) checklist. The quality of psychometric properties was assessed with Terwee’s 2007 quality criteria. After screening 3284 records and assessing 169 full texts for eligibility, fourteen studies on seven trust in physician measures were included. Most of the studies were conducted in the USA and used English measures. All but one measure were generic. Sample sizes range from 25 to 1199 participants, recruited in very heterogeneous settings. Quality assessments revealed several flaws in the methodological quality of studies. COSMIN scores were mainly fair or poor. The overall quality of measures’ psychometric properties was intermediate. Several trust in physician measures have been developed over the last years, but further psychometric evaluation of these measures is strongly recommended. The methodological quality of psychometric property studies could be improved by adhering to quality criteria like the COSMIN checklist.     

Branch,micropropagule and tissue culture of the red algaeEucheuma denticulatum andKappaphycus alvarezii farmed in the Philippines

Three forms of the iota-producing carrageenophyte,Eucheuma denticulatum, and four forms of the kappa-producing carrageenophyte,Kappaphycus alvarezii, obtained from seaweed farms in the Philippines have been grown in the laboratory under unialgal and axenic conditions. Comparison of media indicates that seed stocks of both species can be cultured using enriched seawater media ranging from ESS and SWMD-1 to inexpensive soil extract (Erdshreiber's) or holding in sterile seawater for up to three weeks. Micropropagation has been successful with at least two forms of each species resulting in clonal propagation from axenic explants within 4 to 8 weeks. Callus development and branch regeneration has also been induced in two forms of each species. The results indicate that culture facilities in the farming areas of the Philippines could maintain high-yielding and rapidly growing seed stock for the seaweed farmers.     

EstB from Burkholderia gladioli: a novel esterase with a beta-lactamase fold reveals steric factors to discriminate between esterolytic and beta-lactam cleaving activity

Esterases form a diverse class of enzymes of largely unknown physiological role. Because many drugs and pesticides carry ester functions, the hydrolysis of such compounds forms at least one potential biological function. Carboxylesterases catalyze the hydrolysis of short chain aliphatic and aromatic carboxylic ester compounds. Esterases, D-alanyl-D-alanine-peptidases (DD-peptidases) and beta-lactamases can be grouped into two distinct classes of hydrolases with different folds and topologically unrelated catalytic residues, the one class comprising of esterases, the other one of beta-lactamases and DD-peptidases. The chemical reactivities of esters and beta-lactams towards hydrolysis are quite similar, which raises the question of which factors prevent esterases from displaying beta-lactamase activity and vice versa. Here we describe the crystal structure of EstB, an esterase isolated from Burkholderia gladioli. It shows the protein to belong to a novel class of esterases with homology to Penicillin binding proteins, notably DD-peptidase and class C beta-lactamases. Site-directed mutagenesis and the crystal structure of the complex with diisopropyl-fluorophosphate suggest Ser75 within the "beta-lactamase" Ser-x-x-Lys motif to act as catalytic nucleophile. Despite its structural homology to beta-lactamases, EstB shows no beta-lactamase activity. Although the nature and arrangement of active-site residues is very similar between EstB and homologous beta-lactamases, there are considerable differences in the shape of the active site tunnel. Modeling studies suggest steric factors to account for the enzyme's selectivity for ester hydrolysis versus beta-lactam cleavage.     

In Vivo Validation of In Silico Predicted Metabolic Engineering Strategies in Yeast: Disruption of α-Ketoglutarate Dehydrogenase and Expression of ATP-Citrate Lyase for Terpenoid Production

Background

Engineering of the central carbon metabolism of Saccharomyces cerevisiae to redirect metabolic flux towards cytosolic acetyl-CoA has become a central topic in yeast biotechnology. A cell factory with increased flux into acetyl-CoA can be used for heterologous production of terpenoids for pharmaceuticals, biofuels, fragrances, or other acetyl-CoA derived compounds. In a previous study, we identified promising metabolic engineering targets in S. cerevisiae using an in silico stoichiometric metabolic network analysis. Here, we validate selected in silico strategies in vivo.

Results

Patchoulol was produced by yeast via a heterologous patchoulol synthase of Pogostemon cablin. To increase the metabolic flux from acetyl-CoA towards patchoulol, a truncated HMG-CoA reductase was overexpressed and farnesyl diphosphate synthase was fused with patchoulol synthase. The highest increase in production could be achieved by modifying the carbon source; sesquiterpenoid titer increased from glucose to ethanol by a factor of 8.4. Two strategies predicted in silico were chosen for validation in this work. Disruption of α-ketoglutarate dehydrogenase gene (KGD1) was predicted to redirect the metabolic flux via the pyruvate dehydrogenase bypass towards acetyl-CoA. The metabolic flux was redirected as predicted, however, the effect was dependent on cultivation conditions and the flux was interrupted at the level of acetate. High amounts of acetate were produced. As an alternative pathway to synthesize cytosolic acetyl-CoA, ATP-citrate lyase was expressed as a polycistronic construct, however, in vivo performance of the enzyme needs to be optimized to increase terpenoid production.

Conclusions

Stoichiometric metabolic network analysis can be used successfully as a metabolic prediction tool. However, this study highlights that kinetics, regulation and cultivation conditions may interfere, resulting in poor in vivo performance. Main sites of regulation need to be released and improved enzymes are essential to meet the required activities for an increased product formation in vivo.