Environmental risk assessments for transgenic crops producing output trait enzymes

The environmental risks from cultivating crops producing output trait enzymes can be rigorously assessed by testing conservative risk hypotheses of no harm to endpoints such as the abundance of wildlife, crop yield and the rate of degradation of crop residues in soil. These hypotheses can be tested with data from many sources, including evaluations of the agronomic performance and nutritional quality of the crop made during product development, and information from the scientific literature on the mode-of-action, taxonomic distribution and environmental fate of the enzyme. Few, if any, specific ecotoxicology or environmental fate studies are needed. The effective use of existing data means that regulatory decision-making, to which an environmental risk assessment provides essential information, is not unnecessarily complicated by evaluation of large amounts of new data that provide negligible improvement in the characterization of risk, and that may delay environmental benefits offered by transgenic crops containing output trait enzymes.     

A(3) adenosine receptor deficiency does not influence atherogenesis

Atherosclerosis is a multifactorial disease, the progression of which is modulated by several factors, including inflammation and hypercholesterolemia. The A(3) adenosine receptor (A(3)AR) has been reported to affect mast cell degranulation leading to inflammation, as well as to influence cardiovascular homeostasis. Here, we show that its deletion can also impact vascular smooth muscle cell (VSMC) proliferation in vitro. Based on these observations, we hypothesized that A(3)AR deficiency would affect atheromatous lesion development in vivo. Our results indicate that the expression of the matrix enzyme lysyl oxidase (LO) is increased while the proliferation potential of VSMC is decreased in A(3)AR-null aortas. This is in accordance with the previously reported inverse correlation between LO level and proliferation. Nevertheless, we found that A(3)-deficiency does not protect vessels against atherogenesis. This was demonstrated in mouse models of high fat diet-induced atherosclerosis and guidewire-induced femoral artery injury. We conclude that the contributions of the A(3)AR to inflammation and to modulating LO levels are not significant enough to control vascular response to injury.     

A novel high performing multiplex immunoassay Multi-HTLV for serological confirmation and typing of HTLV infections

BackgroundHuman T-Cell Lymphotropic Viruses (HTLV) type 1 and type 2 account for an estimated 5 to 10 million infections worldwide and are transmitted through breast feeding, sexual contacts and contaminated cellular blood components. HTLV-associated syndromes are considered as neglected diseases for which there are no vaccines or therapies available, making it particularly important to ensure the best possible diagnosis to enable proper counselling of infected persons and avoid secondary transmission. Although high quality antibody screening assays are available, currently available confirmatory tests are costly and have variable performance, with high rates of indeterminate and non-typable results reported in many regions of the world. The objective of this project was to develop and validate a new high-performance multiplex immunoassay for confirmation and discrimination of HTLV-1 and HTLV-2 strains.Methodology/Principal findingsThe multiplex platform was used first as a tool to identify suitable antigens and in a second step for assay development. With data generated on over 400 HTLV-positive blood donors sourced from USA and French blood banks, we developed and validated a high-precision interpretation algorithm. The Multi-HTLV assay demonstrated very high performance for confirmation and strain discrimination with 100% sensitivity, 98.1% specificity and 100% of typing accuracy in validation samples. The assay can be interpreted either visually or automatically with a colorimetric image reader and custom algorithm, providing highly reliable results.Conclusions/SignificanceThe newly developed Multi-HTLV is very competitive with currently used confirmatory assays and reduces considerably the number of indeterminate results. The multiparametric nature of the assay opens new avenues to study specific serological signatures of each patient, follow the evolution of infection, and explore utility for HTLV disease prognosis. Improving HTLV diagnostic testing will be critical to reduce transmission and to improve monitoring of seropositive patients.     

Solution properties of wheat-flour arabinoxylans and enzymically modified arabinoxylans

A series of water-soluble arabinoxylans has been prepared from purified wheat-flour arabinoxylan by partial removal of arabinosyl side-branches using an α-L-arabinofuranosidase. Their solubilities, molecular weights, intrinsic viscosities, and degrees of hydration were measured. The results suggest that the arabinoxylan assumes an extended rod-like conformation in solution. The solubilizing effect of arabinosyl substituents was not the result of increased hydration, but due to their ability to prevent intermolecular aggregation of unsubstituted xylose residues. The extended conformation of arabinoxylan is consistent with its known organization and function in plant cell-walls.     

Characterization of abiotic stress-responsive <Emphasis Type="Italic">Arabidopsis thaliana RD29A</Emphasis> and <Emphasis Type="Italic">RD29B</Emphasis> genes and evaluation of transgenes

Abiotic stresses have adverse effects on plant growth and productivity. The homologous RD29A and RD29B genes are exquisitely sensitive to various abiotic stressors. Therefore, RD29A and RD29B gene sequences have potential to confer abiotic stress resistance in crop species grown in arid and semi-arid regions. To our knowledge, no information on the physiological roles of the proteins encoded by RD29A and RD29B are available in the literature. To understand how these proteins function, we used reverse genetic approaches, including identifying rd29a and rd29b T-DNA knockout mutants, and examining the effects of complementing transgenes with the genes under control of their native promoters and chimeric genes with the native promoters swapped. Four binary vectors with the RD29A and RD29B promoters upstream of the cognate RD29A and RD29B cDNAs and as chimeric genes with noncognate promoters were used to transform rd29a and rd29b plants. Cold, drought, and salt induced both genes; the promoter of RD29A was found to be more responsive to drought and cold stresses, whereas the promoter of RD29B was highly responsive to salt stress. Morphological and physiological responses of rd29a and rd29b plants to salt stress were further investigated. Root growth, and photosynthetic properties declined significantly, while solute concentration (Ψπ), water use efficiency (WUE) and δ¹³C ratio increased under salt stress. Unexpectedly, the rd29a and rd29b knockout mutant lines maintained greater root growth, photosynthesis, and WUE under salt stress relative to control. We conclude that the RD29A and RD29B proteins are unlikely to serve directly as protective molecules.     

Kinetics of Src homology 3 domain association with the proline-rich domain of dynamins: specificity, occlusion, and the effects of phosphorylation

Dynamin function is mediated in part through association of its proline-rich domain (PRD) with the Src homology 3 (SH3) domains of several putative binding proteins. To assess the specificity and kinetics of this process, we undertook surface plasmon resonance studies of the interaction between isolated PRDs of dynamin-1 and -2 and several purified SH3 domains. Glutathione S-transferase-linked SH3 domains bound with high affinity (K(D) approximately 10 nm to 1 microm) to both dynamin-1 and -2. The simplest interaction appeared to take place with the amphiphysin-SH3 domain; this bound to a single high affinity site (K(D) approximately 10 nm) in the C terminus of dynamin-1 PRD, as predicted by previous studies. Binding to the dynamin-2 PRD was also monophasic but with a slightly lower affinity (K(D) approximately 25 nm). Endophilin-SH3 binding to both dynamin-1 and -2 PRDs was biphasic, with one high affinity site (K(D) approximately 14 nm) in the N terminus of the PRD and another lower affinity site (K(D) approximately 60 nm) in the C terminus of dynamin-1. The N-terminal site in dynamin-2 PRD had a 10-fold lower affinity for endophilin-SH3. Preloading of dynamin-1 PRD with the amphiphysin-SH3 domain partially occluded binding of the endophilin-SH3 domain, indicating overlap between the binding sites in the C terminus, but endophilin was still able to interact with the high affinity N-terminal site. This shows that more than one SH3 domain can simultaneously bind to the PRD and suggests that competition probably occurs in vivo between different SH3-containing proteins for the limited number of PXXP motifs. Endophilin-SH3 binding to the high affinity site was disrupted when dynamin-1 PRD was phosphorylated with Cdk5, indicating that this site overlaps the phosphorylation sites, but amphiphysin-SH3 binding was unaffected. Other SH3 domains showed similarly complex binding characteristics, and substantial differences were noted between the PRDs from dynamin-1 and -2. For example, SH3 domains from c-Src, Grb2, and intersectin bound only to the C-terminal half of dynamin-2 PRD but to both the N- and C-terminal portions of dynamin-1 PRD. Thus, differential binding of SH3 domain-containing proteins to dynamin-1 and -2 may contribute to the distinct functions performed by these isoforms.     

Ecological Risk Aversion and Foraging Behaviors of Juvenile Squirrel Monkeys (Saimiri sciureus)

The ‘ecological risk aversion hypothesis’ [C.H. Janson and C.P. van Schaik, Juvenile Primates, Oxford Univ. Press, New York (1993), pp. 57–74] proposes that the pattern of slow growth characteristic of juvenile primates is a response to ecological risks (predation and starvation) experienced by juveniles. Juveniles are thought to avoid predation risk by positioning themselves near conspecifics, therefore experiencing high levels of feeding competition with older individuals, reduced access to resources and, consequently, high starvation risks during periods of food scarcity. The present study compared the foraging behaviors of juvenile and adult squirrel monkeys, a small neotropical primate characterized by a long juvenile period, to determine how predation and starvation risks affected juvenile behaviors. The study was conducted in Eastern Amazonia, in a seasonal environment. Due to their slow development, small body size and large group sizes, it was expected that juveniles in this species would behave in a manner consistent with the risk aversion hypothesis. However, age differences in foraging efficiency and foraging success were smaller than predicted. There was also no evidence that juveniles sacrificed access to food for predator protection. Adults did not have preferential access to fruit patches and direct competition was rare. Feeding competition for prey, the most common resource in the troop's diet, was negligible. Therefore, the slow growth and long juvenile period of squirrel monkeys do not correspond with evidence of predation or starvation risk, as predicted by the risk aversion hypothesis.     

Stable isotope evidence for impala Aepyceros melampus diets at Akagera National Park,Rwanda

Stable isotope analysis of tooth enamel was used to investigate the relative proportions of grass and browse in seasonal and overall diets of impala Aepyceros melampus at Akagera National Park, Rwanda. Bulk enamel samples suggest that on average, impala ate c. 86% C₄ grass year‐round, far more than in most previously studied impala populations across Africa. Intra‐tooth samples show that seasonal changes in the proportion of C₄ grass versus C₃ browse are minimal (c. 10%), the diet being dominated by C₄ grass year‐round in contrast to other impala populations that consume ≥50% browse during the dry season. Intra‐tooth oxygen isotope values track carbon isotope changes to a moderate degree, but are not patterned clearly enough to permit identification of wet versus dry seasons. As other studies have shown that impala select high‐protein diets, the foraging behaviour at Akagera is probably because of the availability of palatable grass for much of the year in the edaphic grasslands around the lacustrine environments of the eastern portions of Akagera National Park.     

Reversible movement of switch 1 loop of myosin determines actin interaction

The conserved switch 1 loop of P-loop NTPases is implicated as a central element that transmits information between the nucleotide-binding pocket and the binding site of the partner proteins. Recent structural studies have identified two states of switch 1 in G-proteins and myosin, but their role in the transduction mechanism has yet to be clarified. Single tryptophan residues were introduced into the switch 1 region of myosin II motor domain and studied by rapid reaction methods. We found that in the presence of MgADP, two states of switch 1 exist in dynamic equilibrium. Actin binding shifts the equilibrium towards one of the MgADP states, whereas ATP strongly favors the other. In the light of electron cryo-microscopic and X-ray crystallographic results, these findings lead to a specific structural model in which the equilibrium constant between the two states of switch 1 is coupled to the strength of the actin-myosin interaction. This has implications for the enzymatic mechanism of G-proteins and possibly P-loop NTPases in general.     

The cercal receptor system of the praying mantid,Archimantis brunneriana Sauss.

Summary The cerci of the praying mantid, Archimantis brunneriana Sauss., are paired segmented sensory organs located at the tip of the abdomen. Basally the cercal segments are slightly flattened dorso-ventrally and are fused to such a degree that it is difficult to distinguish them. Distally the segments become progressively more flattened laterally and their boundaries become more obvious.Two types of sensilla are present on the cerci, trichoid sensilla and filiform sensilla. Trichoid hairs are longest on the medial side of the cerci and toward the cercal base. On the proximal cercal segments they are grouped toward the middle of each segment while they are more uniformly distributed on the distal segments. Filiform sensilla are found at the distal end of each segment except the last and are most abundant on the middle segments of the cercus. Both the number of cercal segments and the number of sensilla are variable. Trichoid hairs are highly variable in appearance from short and stout to long and thin. They arise from a raised base, have a fluted shaft, and some have a pore at the tip. They are innervated by from one to five dendrites, one of which is always considerably larger than the others. Some of the dendrites continue out into the shaft of the hair.Filiform hairs have fluted shafts and are mounted in a flexible membrane within a cuticular ring in a depression. They are innervated by a single large sensory neuron, the dendrite of which passes across a flattened area on the inner wall of the lumen of the hair. The dendritic sheath forms the lining of the ecdysial canal and is therefore firmly attached to the hair. The dendrite is attached to the sheath by desmosomes distally and is penetrated by projections of the sheath more proximally. A fibrous cap surrounds the dendrite and may hold it in place relative to the hair.The cercal receptor system of Archimantis is compared to those of cockroaches and crickets.