Role of actin in the cAMP-dependent activation of sodium/glucose cotransporter in renal epithelial cells

We examined whether actin filaments are involved in the cAMP-dependent activation of a high affinity sodium/glucose cotransporter (SGLT1) using epithelial expression systems. The expression of enhanced green fluorescent protein-tagged SGLT1 (EGFP-SGLT1) in Madin-Darby canine kidney (MDCK) cells was revealed by Western blotting and confocal laser microscopy. 8-Br-cAMP, a membrane permeable cAMP analog, enhanced [¹⁴C]-α-methyl glucopyranoside ([¹⁴C]-AMG) uptake. Both basal and 8-Br-cAMP-elicited [¹⁴C]-AMG uptakes were inhibited by N-(2{[3-(4-bromophenyl)-2-propenyl]-amino}-ethyl)-5-isoquinolinesulfonamide (H-89), a protein kinase A inhibitor, and cytochalasin D, an actin filament formation inhibitor. Furthermore, cytochalasin D inhibited the distribution of EGFP-SGLT1 at the apical surface. These results suggest that the EGFP-SGLT1 protein is functionally expressed in the apical membrane of MDCK cells, and is up-regulated by a cAMP-dependent pathway requiring intact actin filaments.     

Changes in DTPA-iron and management of iron chlorosis in rice nurseries

Summary On a Typic Ustochrept soil incorporation of 10 tons/ha of a green manure plus submergence for 10 days followed by raising upland nursery checked iron chlorosis. In contrast, presubmergence with and without FYM and iron sulfate or pyrite were a failure. Nor weekly sprays with 3.0% iron sulfate were found very effective. The success of green manure plus submergence was associated with the mobilization of soil iron as a result of intense reduction and its subsequent retention in available form at a sufficient high level during the growth of upland nursery.     

P-31 in-vivo NMR investigation on the function of polyphosphates as phosphate-and energysource during the regreening of the green alga Chlorella fusca

The green alga Chlorella fusca accumulates polyphosphates under conditions of nitrogen starvation while deassembling the photosynthetic apparatus. The polyphosphate content of cells regreening after resupply with nitrate under different culture conditions was investigated by P-31 in-vivo NMR spectroscopy. Neither phosphate deficiency nor anaerobiosis during the first hours of regreening inhibited the recovery of the cells. Polyphosphates were degraded during regeening. Differences in the amount of polyphosphates of phosphate supplied and deficient cells occurred only after more then 8 h. After 16 h phosphate deficient cells had still 75% of the polyphosphate content of phosphate suppled cells. In cells kept under anaerobic conditions polyphosphate degradation was much higher than in oxygen supplied cells. After 8 h they contained less than 50% of the polyphosphate content of oxygen supplied cells. These data suggest that polyphosphates serve as obligatory phosphate source during regreening and may be used as an energy source.Non standard abbreviations EDTA Ethylene diamine tetraacetic acid - FID Free induction decay - MOPSO 3-(N-morpholine)-2-hydroxy-propanesulfonic acid - NMR Nuclear magnetic resonance - PP Polyphosphates - PP₄ central phosphate groups of polyphosphates     

Fine structure of the zoospore ofUlothrix belkae with emphasis on the flagellar apparatus

Summary The anterior end of the zoospore ofUlothrix belkae has been examined in detail and is compared toStigeoclonium and other filamentous green algae. The nature of the symmetry of green algal motile cells is discussed and the term, 180° rotational symmetry, is proposed to describe the type of arrangement of anterior end components seen inU. belkae, including the four basal bodies, rootlets and striated fibers. The four microtubular rootlets are cruciately arranged. A striated microtubule-associated component (SMAC) has a periodicity of 6.4 nm and extends with each 2-membered rootlet posteriorly into the cell. One 5-membered rootlet passes very near the eyespot. Phylogeny in green algal motile cells is discussed.     

Preparation of protoplasts from the green alga Enteromorpha intestinalis (L.) Link

Protoplasts have been obtained from vegetative thallus of the green seaweed Enteromorpha following enzymic digestion with driselase and pectinase. The viability of purified protoplast fractions was assessed by staining and measurements of O₂ uptake and evolution.Abbreviations MES 2-(N-morpholino) ethanesulphonic acid - TES N-tris(hydoxymethyl) methyl-2 aminoethanesulphonic acid     

Photosynthetic responses of Eucalyptus nitens (Deane and Maiden) Maiden to green pruning

 Three-year-old Eucalyptus nitens (Deane and Maiden) Maiden trees and 1-year-old ramets of a single clone of E. nitens were pruned to remove 0, 50% or 70% of the green crown length. This was equivalent to removal of 0, 55% or 88% of foliage area of trees, and 0, 77% or 94% of foliage area of ramets. CO₂ assimilation (A) and stomatal conductance (g_s) were measured at constant illumination in five height zones and three foliage-age classes of trees over a 16-month period following pruning. Foliar nitrogen (N) and phosphorus (P) concentrations were determined for each measurement time during the first 12 months of the experiment. In ramets A and g_s were measured in four height zones and two foliage-age classes over a six-week period, and N and P concentrations were measured only once, at the end of the experiment. Rates of A increased by up to 175% following pruning. This response occurred throughout the canopy irrespective of position in the crown or foliage age. The magnitude of the response was generally greater in ramets than in trees, and increased with increasing severity of pruning. The initiation of the response was later, and the duration of the response was longer, in trees than ramets. In the lower crown of trees there was evidence of delayed senescence following pruning. Photosynthetic enhancement was not related to changes in foliar N concentrations. The ratio of A/N increased in many zones following pruning, especially after more severe defoliation. There was no evidence that changes in P concentrations were responsible for the result. The increases in A may have been related to changes in g_s, as maximum values of g_s were greater, and the ratio of A/g_s was generally lower, in pruned than unpruned plants. Received: 31 December 1996 / Accepted: 19 August 1997     

Secretory delivery of heterologous proteins in attenuated <Emphasis Type="Italic">Vibrio anguillarum</Emphasis> for potential use in vaccine design

To synthesize and secrete heterologous proteins in an attenuated Vibrio anguillarum strain for potential multivalent live vaccine development, different antigen-delivery systems based on bacterial-originated secretion signal peptides (SPs) were designed and identified in this work. Four SPs were derived from hemolysin of Escherichia coli, RTX protein of V. cholerae, hemolysin of V. anguillarum, zinc-metalloprotease of V. anguillarum, respectively, and their abilities to support secretion of green fluorescent protein (GFP) in an attenuated V. anguillarum strain MVAV6203 were assayed. Immunodetection of GFP showed that the capability of the tested signal leaders to direct secretion of GFP varied greatly. Although all the four signal peptide-fused GFPs could be expressed correctly and trapped intracellularly in recombinant strains, only the EmpA signal peptide could confer efficient secretion to GFP. For the investigation of its potential application in live bacteria carrier vaccines, a heterologous protein EseB of Edwardsiella tarda was fused to the SP(empA) antigen-delivery system and introduced into the strain MVAV6203. Further analysis of EseB demonstrated that the constructed SP(empA) antigen-delivery system could be used to secrete foreign protein in attenuated V. anguillarum and be available for carrier vaccines development.     

Protected areas in the world’s ecoregions: How well connected are they?

Protected areas (PAs) are the main instrument for biodiversity conservation, which has triggered the development of numerous indicators and assessments on their coverage, performance and efficiency. The connectivity of the PA networks at a global scale has however been much less explored; previous studies have either focused on particular regions of the world or have only considered some types of PAs.Here we present, and globally assess, ProtConn, an indicator of PA connectivity that (i) quantifies the percentage of a study region covered by protected connected lands, (ii) can be partitioned in several components depicting different categories of land (unprotected, protected or transboundary) through which movement between protected locations may occur, (iii) is easy to communicate, to compare with PA coverage and to use in the assessment of global targets for PA systems.We apply ProtConn to evaluate the connectivity of the PA networks in all terrestrial ecoregions of the world as of June 2016, considering a range of median dispersal distances (1–100 km) encompassing the dispersal abilities of the large majority of terrestrial vertebrates.We found that 9.3% of the world is covered by protected connected lands (average for all the world’s ecoregions) for a reference dispersal distance of 10 km, increasing up to 11.7% for the largest dispersal distance considered of 100 km. These percentages are considerably smaller than the global PA coverage of 14.7%, indicating that the spatial arrangement of PAs is only partially successful in ensuring connectivity of protected lands. The connectivity of PAs largely differed across ecoregions. Only about a third of the world’s ecoregions currently meet the Aichi Target of having 17% of the terrestrial realm covered by well-connected systems of PAs. Finally, our findings suggest that PAs with less strict management objectives (allowing the sustainable use of resources) may play a fundamental role in upholding the connectivity of the PA systems.Our analyses and indicator make it possible to identify where on the globe additional efforts are most needed in expanding or reinforcing the connectivity of PA systems, and can be also used to assess whether newly designated sites provide effective connectivity gains in the PA system by acting as corridors or stepping stones between other PAs. The results of the ProtConn indicator are available, together with a suite of other global PA indicators, in the Digital Observatory for Protected Areas of the Joint Research Centre of the European Commission.     

The rare Chrysopidae (Neuroptera) of southwestern Europe

Quantitative surveys of the chrysopid fauna from southwestern Europe, namely the Iberian and Italian peninsulas, France south of 46° N, and the west-Mediterranean Islands, were analysed. A total of 56 species of Chrysopidae were reported, of which three species were abundant. These, Chrysoperla carnea (Stephens, 1836) sensu lato, Dichochrysa prasina (Burmeister, 1839) and D. flavifrons (Brauer, 1850), comprised a large percentage of the specimens. For the rarer species, comments are made on their distributions, the enhanced geographic range of exotic ones, and on levels of endemism and stenotopy.     

Cellular analysis of host cell infection by different developmental stages of Trypanosoma cruzi

Trypanosoma cruzi is an obligate intracellular parasite that infects phagocytic and non-phagocytic mammalian cells by a complex process that appears to involve several discrete steps. Even though the infection process was described many years ago, the molecular mechanisms involved remain poorly understood. As fluorescent proteins have proven to be excellent tools for live-cell imaging, we used EGFP- and DsRed1-1-transfected trypomastigotes, amastigotes and epimastigotes to study the infection process in living cells. Contrary to what has been reported, our results showed that epimastigotes are as infective as trypomastigotes and amastigotes. Besides, differences in replication, differentiation and parasite release times were observed among the stages. Our results suggest that the different developmental stages use distinct attachment and invasion mechanisms. We propose that fluorescent-based plasmid expression systems are good models for studying the infection process of intracellular microorganisms and could offers insights about the molecular mechanisms involved.