Local grassland restoration affects insect communities

1. It is hypothesised that ecological restoration in grasslands can induce an alternative stable state shift in vegetation. The change in vegetation influences insect community assemblages and allows for greater functional redundancy in pollination and refuge for native insect species. 2. Insect community assemblages at eight coastal California grassland sites were evaluated. Half of these sites had undergone restoration through active revegetation of native grassland flora and half were non‐restored. Insects were collected from Lupinus bicolor (Fabaceae) within 2 × 2‐m² plots in spring 2017. Lupinus bicolor is a common native species that is used in California restoration projects, and home and state landscaping projects. 3. Ordination demonstrated that insect community assemblages were different between restored and non‐restored sites. These differences were seen in insect functional groups as well as taxa‐specific differences and were found to be driven by environmental characteristics such as non‐native forb cover. 4. Functional redundancy of herbivores decreased at restored sites, while pollinators became more redundant compared with non‐restored sites. The assemblages of the common species found at restoration sites contained more native insects than those found at non‐restored sites, including species such as Bombus vosnesenskii. 5. Local grassland restoration has the potential to induce an alternative stable state change and affect insect community assemblages. Additionally, it was found that grassland restoration can be a potential conservation tool to provide refugia for bumblebees (Bombus), but additional studies are required to fully understand its broader applicability.     

Cell surface heparan sulfate proteoglycans from human vascular endothelial cells. Core protein characterization and antithrombin III binding properties.

Human aortic endothelial cells (HAEC) and human umbilical vein endothelial cells (HUVEC) were labeled with 35SO(4)2- for 48 h. The membrane-associated proteoglycans were solubilized from these monolayers with detergent and purified by ion-exchange chromatography on Mono Q, incorporation in liposomes, and gel filtration. The liposome-intercalated proteoglycans were 125I-iodinated and treated with heparitinase before SDS-polyacrylamide gel electrophoresis. Radio-labeled proteins with apparent molecular masses of 130, 60, 46, 35, and 30 kDa (HAEC) and 180, 130, 62, 43, and 35 kDa (HUVEC) were detected by autoradiography. Further characterization by affinity chromatography on immobilized monoclonal antibodies and by Northern blot analysis provided evidence for the expression of syndecan, glypican, and fibroglycan in human endothelial cells. Most of the heparan sulfate which accumulated in the subendothelial matrix was implanted on a 400-kDa core protein. This protein was immunologically related to perlecan and bound to fibronectin. Binding studies on immobilized antithrombin III suggested that all membrane-associated heparan sulfate proteoglycan forms had the capacity to bind to antithrombin III but that high affinity binding was more typical for glypican. Most of the proteoglycans isolated from the extracellular matrix also bound only with low affinity to antithrombin III. These results imply that glypican may specifically contribute to the antithrombotic properties of the vascular wall.     

Bacteriophage-resistance mechanisms examined by transfection of Lactococcus lactis subsp. lactis 4513-5 mediated by high voltage electroporation

Summary Phage adsorption tests and transfection by electroporation were carried out to decide whether phage-resistance in Lactococcus lactis subsp. lactis strain 4513-5 is based on intracellular or extracellular mechanisms. Using high voltage (12.5 kV/cm) electroporation, untreated phage DNA was introduced into phage-sensitive and phage-resistant cells. Since phages showed low adsorption frequencies on resistant bacteria, resistance is localized in the cell wall preventing phage DNA from entering the cell. This is the only mechanism responsible for the resistance of L. lactis subsp. lactis 4513-5 against its homologous phage P4513-K12 and non-homologous phages P05M-13 and P05M-47, but not against phage P530-7 and phage P530-12. In the case of the latter two phage strains, intracellular resistance mechanisms are involved and discussed.     

Effect of ethylene treatment on the concentration of fructose-2,6-bisphosphate and on the activity of phosphofructokinase 2/fructose-2,6-bisphosphatase in banana

Preclimacteric bananas fruits were treated for 12 h with ethylene to induce the climacteric rise in respiration. One day after the end of the hormonal treatment, the two activities of the bifunctional enzyme, phosphofructokinase 2/fructose-2,6-bisphosphatase started to increase to reach fourfold their initial value 6 days later. By contrast, the activities of the pyrophosphate-dependent and of the ATP-dependent 6-phosphofructo-1-kinases remained constant during the whole experimental period, the first one being fourfold greater than the second. The concentrations of fructose 2,6-bisphosphate and of fructose 1,6-bisphosphate increased in parallel during 4 days and then slowly decreased, the second one being always about 100-fold greater than the first. The change in fructose 2,6-bisphosphate concentration can be partly explained by the rise of the bifunctional enzyme, but also by an early increase in the concentration of fructose 6-phosphate, the substrate of all phosphofructokinases, and also by the decrease in the concentration of glycerate 3-phosphate, a potent inhibitor of phosphofructokinase 2. The burst in fructose 2,6-bisphosphate and the activity of the pyrophosphate-dependent phosphofructokinase, which is in banana the only enzyme known to be sensitive to fructose 2,6-bisphosphate, can explain the well-known increase in fructose 1,6-bisphosphate which occurs during ripening.     

Fructose 2,6-bisphosphate hydrolyzing enzymes in higher plants

The phosphatases that hydrolyze fructose 2,6-bisphosphate in a crude spinach (Spinacia oleracea L.) leaf extract were separated by chromatography on blue Sepharose, into three fractions, referred to as phosphatases I, II, and III, which were further purified by various means. Phosphatase I hydrolyzed fructose 2,6-bisphosphate, with a K_m value of 30 micromolar, to a mixture of fructose 2-phosphate (90%) and fructose 6-phosphate (10%). It acted on a wide range of substrates and had a maximal activity at acidic pH. Phosphatase II specifically recognized the osyl-link of phosphoric derivatives and had more affinity for the β-anomeric form. Its apparent K_m for fructose 2,6-bisphosphate was 30 micromolar. It most likely corresponded to the fructose-2,6-bisphosphatase described by F. D. Macdonald, Q. Chou, and B. B. Buchanan ([1987] Plant Physiol 85: 13-16). Phosphatase III copurified with phosphofructokinase 2 and corresponded to the specific, low-K_m (24 nanomolar) fructose-2,6-bisphosphatase purified and characterized by Y. Larondelle, E. Mertens, E. Van Schaftingen, and H. G. Hers ([1986] Eur J Biochem 161: 351-357). Three similar types of phosphatases were present in a crude extract of Jerusalem artichoke (Helianthus tuberosus) tuber. The concentration of fructose 2,6-bisphosphate decreased at a maximal rate of 30 picomoles per minute and per gram of fresh tissue in slices of Jerusalem artichoke tuber, upon incubation in 50 millimolar mannose. This rate could be accounted for by the maximal extractable activity of the low-K_m fructose-2,6-bisphosphatase. A new enzymic method for the synthesis of β-glucose 1,6-bisphosphate from β-glucose 1-phosphate and ATP is described.     

Dietary zinc deficiency has no effect on auditory brainstem responses in the rat

Zinc has been shown to effect--in vitro--a number of processes associated with neurotransmission. We have tested whether the rate of impulse conduction--in vivo--as measured from the latencies of auditory brainstem responses (ABR), is influenced by dietary zinc deficiency in the rat. Dietary zinc deficiency for up to 26 wk had no effect on the wave I-IV interval compared to zinc-adequate fed animals. The results are discussed in relation to the observed constancy of brain overall and extracellular fluid zinc concentrations under conditions of dietary zinc deficiency.     

Monoclonal antibodies to plant growth regulators. II. Indole-3-acetic acid

The production and characterization of high-affinity monoclonal antibodies suitable for the radio- and enzymeimmunoassay of the endogenous plant growth regulator, indole-3-acetic acid (IAA), is reported. Hybridomas were produced by fusion of NS 1 myeloma cells with spleen cells from Balb/c mice immunized with IAA-bovine serum albumin conjugates. From an initial collection of 158 wells containing cells secreting monoclonal antibodies against IAA, seven were used to derive cell clones. Three of these are described here. They secrete immunoglobulin (IgG2a or IgG2b) of high affinity and specificity for IAA methyl ester and can be used to quantite picogram amounts of this compound in plant extracts by radio- and enzymeimmunoassay.     

G inversion in bacteriophage Mu DNA is stimulated by a site within the invertase gene and a host factor

The Gin function of bacteriophage Mu catalyzes inversion of the G DNA segment, thus switching the host range of Mu phage particles. This site-specific recombination event takes place between inverted repeat sequences (IR) that border the G segment. Sequences in the Mu beta region extending approximately from position 118 to 178 are essential for efficient inversion. In cis this region, termed sis, stimulates inversion about 15-fold. Neither the relative orientation of sis with respect to the IR sequences nor the distance to IR substantially influences the stimulatory effect. For full activity purified Gin protein must be supplemented with crude host factor from E. coli K12. We suggest that, in addition to Gin, a DNA-binding host protein is required for efficient G inversion.