Self-assembly and Self-replication of Short Amphiphilic β-sheet Peptides

Most self-replicating peptide systems are made of α-helix forming sequences. However, it has been postulated that shorter and simpler peptides may also serve as templates for replication when arranged into well-defined structures. We describe here the design and characterization of new peptides that form soluble β-sheet aggregates that serve to significantly accelerate their ligation and self-replication. We then discuss the relevance of these phenomena to early molecular evolution, in light of additional functionality associated with β-sheet assemblies.     

Identification of single tiny seeds ofOrobanche using RAPD analysis

The tiny seeds of parasitic weeds of the genusOrobanche can be identified by using RAPD markers. A simple procedure for DNA extraction from single seeds, 10 μg each, followed by RAPD-PCR and using specific DNA markers, leads to species identification. Seeds of five different species could be identified using this method.     

Repressor and int synthesis of bacteriophage lambda in the E. coli host mutant ER437.

Summary Analysis of phage infection of the host mutant ER437 by SDS polyacrylamide gel electrophoresis and autoradiography has revealed altered expression of repressor and integration function (Int). We show that in this host Int as well as repressor synthesis is not dependent upon the cIII gene product in the usual manner, nor is their synthesis turned off in the normal way.     

The synergistic anti-inflammatory effects of lycopene, lutein, β-carotene, and carnosic acid combinations via redox-based inhibition of NF-κB signaling

Inflammatory mediators and cytokines play important roles in the pathogenesis of a vast number of human diseases; therefore much attention is focused on blunting their proinflammatory modes of action. The aims of the present research were to assess the effectiveness of combinations of carotenoids and phenolics, at concentrations that can be achieved in blood, to inhibit the release of inflammatory mediators from macrophages exposed to lipopolysaccharide (LPS) and to determine what the anti-inflammatory effect of the phytonutrient combinations was in an in vivo mouse model of peritonitis. Preincubation of mouse peritoneal macrophages with lycopene (1μM) or Lyc-O-Mato (1μM) and carnosic acid (2μM), lutein (1μM), and/or β-carotene (2μM) 1h before addition of LPS for 24h caused a synergistic inhibition of NO, prostaglandin E(2), and superoxide production derived from downregulation of iNOS, COX-2, and NADPH oxidase protein and mRNA expression and synergistic inhibition of TNFα secretion. We surmise that the anti-inflammatory action of the phytonutrient combinations used probably resides in their antioxidant properties, because they caused an immediate, efficient, and synergistic inhibition of LPS-induced internal superoxide production leading to a marked decrease in ERK and NF-κB activation. The anti-inflammatory effects of the selected phytonutrient combinations were also demonstrated in a mouse model of peritonitis: their supplementation in drinking water resulted in attenuation of neutrophil recruitment to the peritoneal cavity and in inhibition of inflammatory mediator production by peritoneal neutrophils and macrophages.     

How persons become things: economic and epistemological changes among Nayaka hunter‐gatherers

The ontologies and epistemologies of hunter‐gatherers have attracted growing attention in recent years as these people are undergoing changes. We examine these changes, focusing on one particular case based on our studies of the South Indian Nayaka; they have recently added cultivation and animal husbandry to their partially ongoing hunting and gathering life‐style. Resisting analysis based on an assumed forest/domesticated dichotomy, we show that forest and domesticated animals and plants are both regarded as sentient co‐dwellers in some cases, and as objects in others, depending not on what they are in essence, or where they are, but on when, by whom, and for what purpose they are approached. We argue that pockets of utilitarian framing emerge within the continuing relational epistemology of the Nayaka along with a growing departure from immediacy in the production‐consumption nexus. In these pockets, the vivid presence of animals and plants is concealed, and they no longer appear as persons but as things.     

Further support for the involvement of phytoehrome in stomatal movement

The involvement of phytochrome in stomatal movement in Commelina communis L. is indicated by the following observations: 1) Short irradiation with red or blue light causes opening, of isolated stomata and swelling of guard cell protoplasts. This is reversed by subsequent far red irradiation. 2) In a similar way, stomatal response to prolonged irradiation with red or blue light is decreased by concomitant far red irradiation. 3) Pretreatment with filipin, which interferes with phytochrome binding to membranes, decreases stomatal opening in red and blue light. The stomatal responses to blue and red light are modified by DCMU, N₂, CO_2-enriched atmosphere, and CO_2-free air, which are known to affect, among other processes, chlorophyll fluorescence. Increased chlorophyll fluorescence by DCMU, N₂ and CO₂-enriched atmosphere enhanced stomatal opening in blue light and inhibited it in red light. CO₂-free air, which decreases chlorophyll fluorescence, had the opposite effect.     

K, Mg-ATPase activity in guard cells of Commelina communis

Siliqua development was studied in the wild type line Landsberg erecta and the GA-sensitive mutant ga-1 of Arabidopsis thaliana (L.) Heynh. Reciprocal crosses between wild type and ga-l mutant, and self pollinations of either parent have shown that siliqua growth is determined by endogenous GAs originating from maternal tissues and embryo. The ga-1 mutant either self pollinated or cross-pollinated with wild type pollen showed reduced siliqua growth, which to a large extent could be overcome by exogenously applied GAs. The siliquae of the ga-1 mutant possessed very reduced ent -kaurene synthesizing capacity and no detectable endogenous GA-activity indicating an early block in the GA-biosynthetic pathway. Seed weight is not affected by GA-deficiency during development.     

The role of pre-symbiotic auxin signaling in ectendomycorrhiza formation between the desert truffle <Emphasis Type="Italic">Terfezia boudieri</Emphasis> and <Emphasis Type="Italic">Helianthemum sessiliflorum</Emphasis>

The ectendomycorrhizal fungus Terfezia boudieri is known to secrete auxin. While some of the effects of fungal auxin on the plant root system have been described, a comprehensive understanding is still lacking. A dual culture system to study pre mycorrhizal signal exchange revealed previously unrecognized root–fungus interaction mediated by the fungal auxin. The secreted fungal auxin induced negative taproot gravitropism, attenuated taproot growth rate, and inhibited initial host development. Auxin also induced expression of Arabidopsis carriers AUX1 and PIN1, both of which are involved in the gravitropic response. Exogenous application of auxin led to a root phenotype, which fully mimicked that induced by ectomycorrhizal fungi. Co-cultivation of Arabidopsis auxin receptor mutants tir1-1, tir1-1 afb2-3, tir1-1 afb1-3 afb2-3, and tir1-1 afb2-3 afb3-4 with Terfezia confirmed that auxin induces the observed root phenotype. The finding that auxin both induces taproot deviation from the gravity axis and coordinates growth rate is new. We propose a model in which the fungal auxin induces horizontal root development, as well as the coordination of growth rates between partners, along with the known auxin effect on lateral root induction that increases the availability of accessible sites for colonization at the soil plane of fungal spore abundance. Thus, the newly observed responses described here of the root to Terfezia contribute to a successful encounter between symbionts.     

Phytochrome involvement in stomatal movement in Pisum sativum, Vicia faba and Pelargonium sp.

Red and blue light triggered the opening of isolated stomata of Pisum sativum L. cv. Peleg Alvador, Vicia faba L. (unknown cultivar) and Pelargonium sp. The stimulatory effect of short irradiation with red or blue light was reversed by a subsequent short irradiation with far-red light. In Pisum the stimulatory effect of a continuous irradiation with red or blue light was also abolished by a concomitant far-red light. In leaf pieces of P. sativum blue light was more effective than red, but not in isolated guard cells. In the presence of mesophyll, DCMU inhibited stomatal opening in red light more than in blue, and thus increased the relative response to blue light. This was less evident in isolated guard cells.     

Stomatal response to ATP mediated by phytochrome

External ATP stimulated stomatal opening in epidemal strips of Commelina communis L. in darkness following brief irradiation with white or red light. ATP had no effect in darkness after irradiation with far red light or in continuous light. Mg²⁺ stimulated stomatal response to ATP, which was shown to be taken-up by the tissue. This implies that a Mg-stimulated ATPase, that interacts with Pfr, may be involved in stomatal opening.