The morphogenesis of dimorphic pollen and anthers in Tripogandra amplexicaulis. Light microscopy and growth analysis

A characteristic of the genus Tripogandra is the presence of two dissimilar whorls of anthers. In T. amplexicaulis the short filamented anthers (S anthers) develop fertile, spheroidal pollen, the long filamented ones (L anthers) develop elongated spores, which degenerate prior to anthesis. Meiosis is regular in both types but occurs approximately two days later in the L anthers. Developmental traits of the L spores are a continuous, uniaxial extension and a sigmoid course of growth in volume accompanied by progressive vacuolarization and growth of starch grains and usually no division. The number of spores in the L anthers amounts to only 60 % of that in the S anthers, but the values for anther fresh weight and pollen sac volume of the former eventually exceed those of the latter and the relative growth rate in these variables is consistently higher in the L anthers. The relative rate in dry weight, however, is similar for both anthers and the absolute rate is clearly lower in the L anthers. These growth characteristics are reflected in a greater vacuolarization of both spores and the amoeboid tapetum in the L anthers. Cytological features of male sterile plants with hypotrophy of the tapetum are related to the sterility syndrome of the L anthers and a common hypothesis for the deviating features is presented.     

Bovine Brain Myelin Glycerophosphocholine Choline Phosphodiesterase is an Alkaline Lysosphingomyelinase of the eNPP-Family, Regulated by Lysosomal Sorting

Glycerophosphocholine choline phosphodiesterase (GPC-Cpde) is a glycosylphosphatidylinositol (GPI)-anchored alkaline hydrolase that is expressed in the brain and kidney. In brain the hydrolase is synthesized by the oligodendrocytes and expressed on the myelin membrane. There are two forms of brain GPC-Cpde, a membrane-linked (mGPC-Cpde) and a soluble (sGPC-Cpde). Here we report the characterisation sGPC-Cpde from bovine brain. The amino acid sequence was identical to ectonucleotide pyrophosphatase/phosphodiesterase 6 (eNPP6) precursor, lacking the N-terminal signal peptide region and a C-terminal stretch, suggesting that the hydrolase was solubilised by C-terminal proteolysis, releasing the GPI-anchor. sGPC-Cpde existed as two isoforms, a homodimer joined by a disulfide bridge linking C414 from each monomer, and a monomer resulting from proteolysis N-terminally to this disulfide bond. The only internal disulfide bridge, linking C142 and C154, stabilises the choline-binding pocket. sGPC-Cpde was specific for lysosphingomyelin, displaying 1 to 2 orders of magnitude higher catalytic activity than towards GPC and lysophosphatidylcholine, suggesting that GPC-Cpde may function in the sphingomyelin signaling, rather than in the homeostasis of acylglycerophosphocholine metabolites. The truncated high mannose and bisected hybrid type glycans linked to N118 and N341 of sGPC-Cpde is a hallmark of glycans in lysosomal glycoproteins, subjected to GlcNAc-1-phosphorylation en route through Golgi. Thus, sGPC-Cpde may originate from the lysosomes, suggesting that lysosomal sorting contributes to the level of mGPC-Cpde on the myelin membrane.     

Dihydrofurocoumarin glucosides from Angelica archangelica and Angelica silvestris

A water-soluble root extract of Angelica archangelica subsp. litoralis afforded, in addition to adenosine, coniferin and the two known dihydrofurocoumarin glycosides, apterin and 1′-O-β-d-glycopyranosyl-(S)-marmesin (marmesinin), two new dihydrofuranocoumarin glycosides, 1′-O-β-d-glucopyranosyl-(2S, 3R)-3-hydroxymarmesin, and 2′-β-d-glucopyranosyloxymarmesin. For the latter a 2S-configuration was demonstrated, the stereochemistry at position 1′ remaining undefined. Roots of A. silvestris similarly afforded 1′-O-β-d-glucopyranosyl-(2S, 3R)-3-hydroxymarmesin. By correlation with the aglycone 2S,3R)-3-hydroxymarmesin obtained in this work, the absolute configurations (2S,3R) were established for the known dihydrofurocoumarin diesters smirniorin and smirnioridin.     

Activity of ectoenzymes of the heart breaking up ATP in the period of myocardial reperfusion after ischemia

Nowadays the activity of heart ectoenzymes, breaking up ATP, are determined in the undamaged tissue to eliminate the effect to the ATP of intracellular enzymes. Our aim is to study the activity of ecto-adenosine triphosphatase in the heart damaged by ischemia. It was established that the activity of ectoenzymes, breaking up ATP, may be measured in the tissue damaged by ischemia only in case when the cellular membrane becomes impermeable for the intracellular enzymes. The activity of adenosine triphosphatase is significantly reduced during the myocardial reperfusion after ischemia and appeared as one of the criteria by which we can assume the degree of the heart reperfusion damage.     

Crossed hydrophobic interaction immunoelectrophoresis: An analytical method for detection of amphiphilic proteins in crude mixtures and for prediction of the result of hydrophobic interaction chromatography

Crossed hydrophobic interaction immunoelectrophoresis is an analytical technique in which the principles of quantitative immunoelectrophoresis and hydrophobic interaction are directly combined. Using phenyl-Sepharose as hydrophobic (amphiphilic) matrix we have shown how the method permits detection of amphiphilic proteins in three model systems: native- and trypsinated intestinal brush border aminopeptidase, serum proteins, and detergent-solubilized erythrocyte proteins. In the case of first system the relative amounts of the two forms of the enzyme have been determined using immunochemical quantification. Comparison of the present method with column hydrophobic interaction chromatography reveals concordant results for both serum and erythrocyte proteins. Tests of some alkyl-substituted agaroses show that they work in a manner similar to phenyl-Sepharose.     

Rap1 Can Bypass the FAK-Src-Paxillin Cascade to Induce Cell Spreading and Focal Adhesion Formation

We developed new image analysis tools to analyse quantitatively the extracellular-matrix-dependent cell spreading process imaged by live-cell epifluorescence microscopy. Using these tools, we investigated cell spreading induced by activation of the small GTPase, Rap1. After replating and initial adhesion, unstimulated cells exhibited extensive protrusion and retraction as their spread area increased, and displayed an angular shape that was remodelled over time. In contrast, activation of endogenous Rap1, via 007-mediated stimulation of Epac1, induced protrusion along the entire cell periphery, resulting in a rounder spread surface, an accelerated spreading rate and an increased spread area compared to control cells. Whereas basal, anisotropic, spreading was completely dependent on Src activity, Rap1-induced spreading was refractory to Src inhibition. Under Src inhibited conditions, the characteristic Src-induced tyrosine phosphorylations of FAK and paxillin did not occur, but Rap1 could induce the formation of actomyosin-connected adhesions, which contained vinculin at levels comparable to that found in unperturbed focal adhesions. From these results, we conclude that Rap1 can induce cell adhesion and stimulate an accelerated rate of cell spreading through mechanisms that bypass the canonical FAK-Src-Paxillin signalling cascade.     

Health-Related Quality of Life,Self-Efficacy and Enjoyment Keep the Socially Vulnerable Physically Active in Community-Based Physical Activity Programs: A Sequential Cohort Study

Physical inactivity is most commonly found in socially vulnerable groups. Dutch policies target these groups through community-based health-enhancing physical activity (CBHEPA) programs. As robust evidence on the effectiveness of this approach is limited, this study investigated whether CBHEPA programs contribute to an increase in and the maintenance of physical activity in socially vulnerable groups. In four successive cohorts, starting at a six-month interval, 268 participants from 19 groups were monitored for twelve months in seven CBHEPA programs. Data collection was based on repeated questionnaires. Socio-economic indicators, program participation and coping ability were measured at baseline. Physical activity, health-related quality of life and on-going program participation were measured three times. Self-efficacy and enjoyment were measured at baseline and at twelve months. Statistical analyses were based on a quasi-RCT design (independent t-tests), a comparison of participants and dropouts (Mann-Whitney test), and multilevel modelling to assess change in individual physical activity, including group level characteristics. Participants of CBHEPA programs are socially vulnerable in terms of low education (48.6%), low income (52.4%), non-Dutch origin (64.6%) and health-related quality of life outcomes. Physical activity levels were not below the Dutch average. No increase in physical activity levels over time was observed. The multilevel models showed significant positive associations between health-related quality of life, self-efficacy and enjoyment, and leisure-time physical activity over time. Short CBHEPA programs (10–13 weeks) with multiple trainers and gender-homogeneous groups were associated with lower physical activity levels over time. At twelve months, dropouts'' leisure-time physical activity levels were significantly lower compared to continuing participants, as were health-related quality of life, self-efficacy and enjoyment outcomes. BMI and care consumption scored significantly higher among dropouts. In conclusion, Dutch CBHEPA programs reach socially vulnerable, but not necessarily inactive, groups in terms of socio-economic and health-related quality of life outcomes. Our findings suggest that CBHEPA programs particularly contribute to physical activity maintenance in socially vulnerable groups, rather than to an increase in physical activity behaviour over time.     

Evaluation of injury thresholds for predicting severe head injuries in vulnerable road users resulting from ground impact via detailed accident reconstructions

Biomechanics and Modeling in Mechanobiology - The aim of this study was to evaluate the effectiveness of various head injury criteria and associated risk functions in prediction of vulnerable road...