Suberized bundle sheaths in grasses (Poaceae) of different photosynthetic types. II. Apoplastic permeability

Summary The relative hydraulic conductivities of major and minor longitudinal veins, and the apoplastic permeability of the bundle sheaths surrounding all longitudinal and transverse veins were investigated in representatives of the C₃, C₄/NAD-ME, C₄/NAD-ME/PCK intermediate, C₄/PCK and C₄/NADP-ME photosynthetic types. Using the Hagen-Poiseuille equation and measurements of tracheary element diameters, the number of elements in each vein type and the numbers of each vein type, we calculated that 87–99% of the water flow in a longitudinal direction would be expected to occur in the major veins. The permeability of the mestome sheaths and parenchymatous bundle sheaths surrounding the veins was tested using the negatively-charged, fluorescent dye, trisodium 3-hydroxy-5,8,10-pyrenetrisulfonate (PTS). This dye proved nontoxic to plant tissue at a concentration of 0.5%, according to a deplasmolysis test with onion epidermal strips. The PTS concentration achieved in the tested grass leaves was about 0.035%, well below the toxic limit. When a solution of PTS was fed to the leaves by means of a basal cut, the dye moved into the veins of all orders. From there, it moved outward into the surrounding tissues, indicating that the sheaths surrounding the veins of all orders in all species tested were permeable. Therefore, contrary to previous predictions based on structural observations and some tracer studies, bundle sheaths with suberized cell walls do not function as endodermal layers.     

Untersuchungen des β-Lipoproteinsystems nach Berg bei Gesunden,Kranken und Schwangeren

Ohne Zusammenfassung     

Quantitative floral development in Pseudolysimachion (Scrophulariaceae): intraspecific variation and comparison with Veronica and Veronicastrum

Intraspecific variation in floral development was studied in four morphologically distinct strains of Pseudolysimachion longifolium and two of P. spicatum. Size increase of whole buds from living plants of P. longifolium was followed in absolute time. Growth rates were homogeneous within inflorescences and within individual plants, and significantly different between individual plants. Organ growth trajectories (plotted as organ size over gynoecium size) differed little among individuals of Pseudolysimachion belonging to morphologically distinct strains; variation was most pronounced in the calyx. Corolla tube as well as calyx and corolla lobe measurements varied more during the early stages of development than near maturity, suggesting constraints on mature flower form. In addition to intraspecific variation, floral development in Pseudolysimachion was compared with that in related Veronica chamaedrys and Veronicastrum virginicum, using data from a previous study. Mature flowers of Pseudolysimachion have long corolla tubes similar to those of Veronicastrum and long corolla lobes similar to those of Veronica. The trajectories of most organs of Pseudolysimachion were intermediate between those of Veronica and Veronicastrum in position as well as in type of curve, i.e., different trajectories lead to similar end products; thus, the shapes of the mature organs are not strictly homologous and not indicative of close relationship.     

VASCULAR ARCHITECTURE IN ISOPHYLLOUS AND FACULTATIVELY ANISOPHYLLOUS SPECIES OF PENTADENIA (GESNERIACEAE)

The organization and differentiation of primary vascular tissue in isophyllous shoots of Pentadenia crassicaulis and facultatively anisophyllous shoots of P. orientandina (Gesneriaceae) were compared using serial reconstructions and quantitative methods. Despite clear differences in shoot symmetry, both species are vascularized by four sympodia, with trilacunar, split-lateral nodal anatomy. Leaf trace tracheary element number and diameter reflect leaf size differences in P. orientandina: these parameters are significantly greater in the large ventral leaves than in the small dorsal leaves. The median and lateral traces of ventral leaves of this species have a similar number of tracheary elements of equal diameter, while there are significantly more tracheary elements in the median than lateral traces of dorsal leaves. The pattern seen in P. crassicaulis is similar to that seen in the dorsal leaves of P. orientandina. In both species, protoxylem development anticipates differences in mature shoot vasculature. Changes in tracheary element number during ontogeny precede or are approximately coincident with changes in leaf size. These results suggest that the facultative expression of leaf size differences in P. orientandina is associated with opportunistic development and differentiation of the lateral trace.     

Proteolytic inactivation of alpha 1-proteinase inhibitor in vivo: detection, characterization and quantitation of the main fragment excreted in the urine of leukemia patients.

During the search for a therapy response parameter in patients with acute myeloid leukemia, we observed the appearance of a 41 kDa glycoprotein band in the urines of these patients under therapy. To investigate the nature of this molecule and to develop a specific detection system, the protein was isolated and antibodies were raised. Urines and sera of patients and healthy subjects were screened for crossreacting proteins by immunoblotting. Only the leukemia patients showed the urinary 41 kDa protein plus a 53 kDa band. In all sera, including those from healthy donors, a 53 kDa protein was intensely stained. Isolation of the plasma protein and sequence analysis of the urinary protein revealed that alpha 1-proteinase inhibitor is the crossreacting plasma protein and that the 41 kDa molecule is proteolytically modified alpha 1-PI, which has lost its antitryptic activity. Cleavage occurred in the N-terminal part as well as in the reactive site loop of the inhibitor. The 41 kDa truncated inhibitor was also found in the leukemic blast cells. A densitometric method is described for the quantitation of the molecule in the nanomolar range.     

Waiting list mortality and the potential of donation after circulatory death heart transplantations in the Netherlands

Netherlands Heart Journal - With more patients qualifying for heart transplantation (HT) and fewer hearts being transplanted, it is vital to look for other options. To date, only organs from...     

A benign approach to the preparation of freshwater bryozoan statoblasts for scanning electron microscopy (SEM) imaging

Abstract

Several different species of freshwater Bryozoa, belonging to the genera Plumatella, Rumarcanella and Fredericella, were detected within the Northern Mallee Pipeline (NMP) system in Victoria, Australia, that required definitive identification. These organisms produce asexual buds called statoblasts, with valves composed of sclerotised chitin that bear minute micro-ornamentations of considerable taxonomical significance. Imaging and analysis of these distinctive micro-ornamentations using scanning electron microscopy (SEM) is often employed for species identification. Meticulous preparation of statoblast samples is therefore required that necessitates the removal of adhering debris, dehydration and drying—whilst mitigating specimen damage and distortion. This technical note describes an approach whereby each of these three steps have been individually designed to be as benign as possible, using mild detergent/sonication to remove debris, a gradual and gentle dehydration procedure using ethanol, and critical point drying. For the overall process, these methods are chosen to optimise control and to minimise the use of harsh and hazardous chemicals.     

Effects of sampling protocol on the shapes of species richness curves

Aim Scheiner (Journal of Biogeography, 2009, 36 , 2005–2008) criticized several issues regarding the typology and analysis of species richness curves that were brought forward by Dengler (Journal of Biogeography, 2009, 36 , 728–744). In order to test these two sets of views in greater detail, we used a simulation model of ecological communities to demonstrate the effects of different sampling schemes on the shapes of species richness curves and their extrapolation capability. Methods We simulated five random communities with 100 species on a 64 × 64 grid using random fields. Then we sampled species–area relationships (SARs, contiguous plots) as well as species–sampling relationships (SSRs, non‐contiguous plots) from these communities, both for the full extent and the central quarter of the grid. Finally, we fitted different functions (power, quadratic power, logarithmic, Michaelis–Menten, Lomolino) to the obtained data and assessed their goodness‐of‐fit (Akaike weights) and their extrapolation capability (deviation of the predicted value from the true value). Results We found that power functions gave the best fit for SARs, while for SSRs saturation functions performed better. Curves constructed from data of 32² grid cells gave reasonable extrapolations for 64² grid cells for SARs, irrespective of whether samples were gathered from the full extent or the centre only. By contrast, SSRs worked well for extrapolation only in the latter case. Main conclusions SARs and SSRs have fundamentally different curve shapes. Both sampling strategies can be used for extrapolation of species richness to a target area, but only SARs allow for extrapolation to a larger area than that sampled. These results confirm a fundamental difference between SARs and area‐based SSRs and thus support their typological differentiation.     

The use of adjunctive GPIIb/IIIa inhibitors in patients with unstable angina/non-Q-wave MI undergoing percutaneous coronary intervention

Glycoprotein IIb/IIIa receptor inhibitors represent a relatively new therapeutic approach in the field of antiplatelet therapy. Following the development of abciximab a number of small molecule GPIIb/IIIa inhibitors have been introduced such as tirofiban and eptifibatide. In this fast-moving field the interventional cardiologist needs a framework to guide decision-making for the individual patient. This review covers the efficacy and safety data from the clinical trials of GPIIb/IIIa inhibitors in the context of patients undergoing percutaneous coronary intervention for unstable angina/non-Q-wave myocardial infarction. There is an increasing body of evidence to support the efficacy of GPIIb/IIIa inhibitors in reducing the risk of adverse ischemic events in high and low risk patients undergoing percutaneous coronary intervention. A number of unresolved efficacy and safety issues remain, including the duration of treatment before and after intervention; whether a reduction in the heparin dose would further decrease the risk of hemorrhage without affecting the periprocedural thrombotic rate in patients undergoing PTCA with adjunctive GPIIb/IIIa inhibitors; and the cost-effectiveness of this therapy. When a thorough analysis of cost-effectiveness has been made, it will be easier to advocate the widespread use of these agents in all patients undergoing coronary intervention.