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.     

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.     

Production of extracellular enzymes by Thermomonospora curvata during growth on protein-extracted lucerne fibres

After extraction of food protein from lucerne, the residual fibre was used as a carbon and energy source by the thermophilic actinomycete, Thermomonospora curvata. Induction of catabolic exoenzymes during growth for 7 d on the fibre at 53°C in a mineral salts minimal medium was compared with that on a variety of other inductive substrates. A fibre concentration of 1.5% (w/v) was optimal for total protein secretion. The fibre was a poor substrate for amylase production due to lack of inducer rather than to catabolite repression by soluble sugars released during degradation. β-Glucosidase release during growth on the fibre was about 10 times that observed in cultures grown on cellobiose or cellulose, but production of other cellulolytic enzymes was about one-half that produced on cellulose. Pectinolytic activity (measured as polygalacturonate lyase) was equal to that produced on pectin. Cells grown on the fibre released about eight times as much proteinase as those grown on cellulose, but proteolytic activity was transient and decreased rapidly during later growth. Xylanase appeared to be co-ordinately induced with cellulolytic enzymes; comparable maximal activities, observed during growth on either the fibre or cellulose, were three times that produced on xylan or xylose.     

Size and shape of the multicatalytic proteinase from rat skeletal muscle

The multicatalytic proteinase from rat skeletal muscle, a non-lysosomal high molecular weight enzyme active at neutral to alkaline pH, has been examined in the electron microscope as well as by dynamic laser light scattering. Both methods reveal monodisperse particles. Electron micrographs show a cylinder-shaped complex with a diameter of 11 nm and a length of 16 nm in negatively stained, and a diameter of 9.6 nm and a length of 14.3 nm in freeze-dried, heavy metal replicated specimens. The molecule is composed of four rings or disks.     

Inhibition of Swarming of Proteus by Sodium Tetradecyl Sulfate, β-Phenethyl Alcohol,and p-Nitrophenylglycerine

The effects of sodium tetradecyl sulfate (STS), β-phenethyl alcohol (PEA), and p-nitrophenylglycerol (PNPG) on motility, swarming, flagellation, and growth of Proteus were examined. Growth-inhibitory concentrations (GIC) and swarming-inhibitory concentrations (SIC) were determined. A characterization of the swarming-inhibitory efficacy of these compounds was based on their GIC/SIC ratio and their concentration inhibition curves. Using the homologous series of sodium alkyl sulfates as a standard reference, we showed that PNPG was more effective than STS, which was the most effective of the homologous series. PEA was less effective than sodium decyl sulfate but more effective than sodium octyl sulfate. Motility tests in liquid medium and electron microscope investigations indicated that the modes of action of the three compounds, all of which effectively inhibit the swarming of Proteus, are different. Whereas STS and PEA inhibit swarming by inhibition of motility, PNPG seems to act on the swarming mechanism sensu strictori, without impairment of motility. STS immobilizes by inhibition of flagellum formation or by some lytic action on the flagella already synthesized. PEA acts by impairing flagellar function, but leaves the flagella morphologically intact.     

Inhibition of Swarming of Proteus by Sodium Tetradecyl Sulfate, beta-Phenethyl Alcohol, and p-Nitrophenylglycerine

The effects of sodium tetradecyl sulfate (STS), β-phenethyl alcohol (PEA), and p-nitrophenylglycerol (PNPG) on motility, swarming, flagellation, and growth of Proteus were examined. Growth-inhibitory concentrations (GIC) and swarming-inhibitory concentrations (SIC) were determined. A characterization of the swarming-inhibitory efficacy of these compounds was based on their GIC/SIC ratio and their concentration inhibition curves. Using the homologous series of sodium alkyl sulfates as a standard reference, we showed that PNPG was more effective than STS, which was the most effective of the homologous series. PEA was less effective than sodium decyl sulfate but more effective than sodium octyl sulfate. Motility tests in liquid medium and electron microscope investigations indicated that the modes of action of the three compounds, all of which effectively inhibit the swarming of Proteus, are different. Whereas STS and PEA inhibit swarming by inhibition of motility, PNPG seems to act on the swarming mechanism sensu strictori, without impairment of motility. STS immobilizes by inhibition of flagellum formation or by some lytic action on the flagella already synthesized. PEA acts by impairing flagellar function, but leaves the flagella morphologically intact.     

Immunohistochemical absence of adrenergic neurons in the dorsal part of the solitary tract nucleus in sudden infant death

The immunohistochemical distribution of TH and PNMT containing neuronal elements was investigated utilizing peroxidase anti-peroxidase methods in newborn control and sudden infant death syndrome (SIDS) brainstems. The TH immunoreactive neurons, within the medulla oblongata, displayed a similar distribution in both control and SIDS tissue. However, PNMT immunoreactive neurons seen in the dorsal part of the nucleus of tractus solitarius in control tissue were not observed in SIDS tissue. This alteration of adrenergic neurons in the dorsal part of NTS (region reported to be implicated in the control of blood pressure and respiration) could explain the cardiorespiratory disorders in SIDS.     

Agonist-induced desensitization of cholinergically stimulated phosphoinositide breakdown is independent of endogenously activated protein kinase C in HT-29 human colon carcinoma cells.

Activation of M3 muscarinic receptors in HT-29 cells by carbachol rapidly increases polyphosphoinositide breakdown. Pretreatment of these cells with carbachol (0.1 mM) for 5 h completely inhibits the subsequent ability of carbachol to increase [3H]inositol monophosphate ([3H]InsP) accumulation, paralleled by a total loss of muscarinic binding sites. In contrast, protein kinase C (PK-C)-mediated desensitization by incubation with phorbol esters [PMA (phorbol 12-myristate 13-acetate)], leading to a time- and dose-dependent inhibition of cholinergically stimulated InsP release (95% inhibition after 4 h with 0.1 microM-PMA), is accompanied by only a 40% decrease in muscarinic receptor binding, which suggests an additional mechanism of negative-feedback control. Neither carbachol nor PMA pretreatment had any effect on receptor affinity. Incubation with carbachol for 15 min caused a small increase of membrane-associated PK-C activity (15% increase, P less than 0.05) as compared with the potency of phorbol esters (PMA) (3-4-fold increase, P less than 0.01). Long-term incubation (4-24 h) with PMA resulted in a complete down-regulation of cytosolic and particulate PK-C activity. Stimulation of InsP release by NaF (20 mM) was not affected after a pretreatment with phorbol esters or carbachol, demonstrating an intact function of G-protein and phospholipase-C (PL-C) at the effector side. Determination of PL-C activity in a liposomal system with [3H]PtdInsP2 as substrate, showed no change in PL-C activity after carbachol (13 h) and short-term PMA (2.5 h) pretreatment, whereas long-term preincubation with phorbol esters (13 h) caused a small but significant decrease in PL-C activity (19%, P less than 0.05). Our results indicate that agonist-induced desensitization of phosphoinositide turnover occurs predominantly at the receptor level, with a rapid loss of muscarinic receptors. Exogenous activation of PK-C by phorbol esters seems to dissociate the interaction between receptor and G-protein/PL-C, without major effects on total cellular PL-C activity.     

The nervous system of Tricladida. III. Neuroanatomy ofDendrocoelum lacteum andPolycelis tenuis (Plathelminthes,Paludicola): an immunocytochemical study

The organization of the nervous system ofDendrocoelum lacteum (Tricladida, Paludicola, Dendrocelidae) andPolycelis tenuis (Tricladida, Paludicola, Planariidae) was studied by immunocytochemical double staining, using neuropeptide RFamide and serotonin (5-HT) antisera on cryosections. The study confirmed the status of the main nerve cords (MCs) as the most important and stable of the longitudinal cords and supported the hypothesis of a common phylogenetic origin of the MCs in flatworms. The ganglion-like structures along the MCs at the beginning of transverse commissures and laterla branches showed a close contact with ventral fibres of the submuscular nerve plexus indicating an origin from crossing points of insunken ring commissures. The distributional pattern and morphology of the RFamide-IR cell bodies inD. lacteum corresponded to that of neurosecretory cells. Most RFamide-IR cells were unipolar and rounded while 5-HT-IR cells were uni- bi- and multipolar. The neutropile consisted of a dense RFamide-IR and a loose 5-HT-IR network. RFamide dominated in all parts of the genital plexus.