Assessment of the genotoxic potential of benzo(a)pyrene and pp'-dichlorodiphenyldichloroethylene in Zebra mussel (Dreissena polymorpha)

The single-cell gel electrophoresis (SCGE) assay and the micronucleus (MN) test were carried out with haemocytes of Zebra mussel (Dreissena polymorpha) specimens to evaluate the potential genotoxicity of benzo(a)pyrene (BaP) and pp'-dichlorodiphenyldichloroethylene (pp'-DDE, a metabolite of pp'-DDT). Mussels were exposed to three different concentrations (0.1 microg/L, 2 microg/L, 10 microg/L) of each chemical in water during 168 h (SCGE assay) and 96 h (MN test) of exposure under laboratory conditions. These levels correspond to nominal molar concentrations of 0.4 nM, 7.9 nM and 40 nM for BaP and 0.3 nM, 6.2 nM and 31 nM for pp'-DDE, respectively. Concurrently, the levels of toxicants were measured in soft tissues of the mussels by gas-chromatographic analyses, to evaluate their temporal trends and the dose/response relationships. Significant increases of the ratio between the comet length and the diameter of the comet head (LDR) and of micronucleus frequencies in comparison with baseline levels were observed not only for all concentrations of BaP, but also for pp'-DDE (except 0.3 nM). The concentration above which DNA damage starts to be significantly increased was 0.8 nmol/g lipids for BaP and 1.6 nmol/g lipids for pp'-DDE, respectively. The results of these experiments show a clear genotoxic effect on this non-target organism not only for the well-known genotoxicant BaP, but also for the final metabolite of pp'-DDT at soft-tissue concentrations that have been found in several aquatic ecosystems worldwide.     

Anaplasma marginale major surface protein 1a directs cell surface display of tick BM95 immunogenic peptides on Escherichia coli

The surface display of heterologous proteins on live Escherichia coli using anchoring motifs from outer membranes proteins has impacted on many areas of biochemistry, molecular biology and biotechnology. The Anaplasma marginale major surface protein 1a (MSP1a) contains N-terminal surface-exposed repeated peptides (28-289 amino acids) that are involved in pathogen interaction with host cell receptors and is surface-displayed when the recombinant protein is expressed in E. coli. Therefore, it was predicted that MSP1a would surface display on E. coli peptides inserted in the N-terminal repeats region of the protein. The Rhipicephalus (Boophilus) microplus BM86 and BM95 glycoproteins are homologous proteins that protect cattle against tick infestations. In this study, we demonstrated that a recombinant protein comprising tick BM95 immunogenic peptides fused to the A. marginale MSP1a N-terminal region is displayed on the E. coli surface and is recognized by anti-BM86 and anti-MSP1a antibodies. This system provides a novel approach to the surface display of heterologous antigenic proteins on live E. coli and suggests the possibility to use the recombinant bacteria for immunization studies against cattle tick infestations.     

Ginkgo biloba extract EGb 761 protects against mitochondrial aging in the brain and in the liver.

According to the free radical theory of aging, oxygen-derived free radicals causes the age-associated impairment at the cellular and tissue levels. The mitochondrial theory of aging points to mitochondria, and specially mitochondrial DNA, as the major targets of free radical attack upon aging. Thus, oxidative damage to mtDNA accumulate with age in human and rodent tissues and also is inversely related to maximum life span of mammals. Mitochondrial deficits, such as a decrease in mitochondrial membrane potential, occur upon aging due to oxidative damage. The age-related mitochondrial oxidative stress may be prevented by late onset administration of certain antioxidants, such as Ginkgo biloba extract EGb 761. These antioxidants may also delay the physiological impairment associated with aging.     

The influence of the rearing host on the response of the parasitoid Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae) to odours from Ephestia kuehniella and Plodia interpunctella in a Y-tube olfactometer

Venturia canescens (Gravenhorst) is an ichneumonid generalist parasitoid that successfully attacks the larvae of different lepidopteran pests that infest stored products. These pest species include Plodia interpunctella and Ephestia kuehniella. In this study, we aimed to evaluate the influence of the rearing host on the parasitoid’s ability to detect and respond to a new host different from the rearing species. For this reason, the trials tested the preference of parasitoids reared on P. interpunctella or E. kuehniella for products that were or were not infested with larvae of these hosts. The trials were conducted in a Y-tube olfactometer. Regardless of the rearing host species, the parasitoids showed no preference for uninfested products. The parasitoids were attracted to products infested with larvae of their rearing host in preference to uninfested products. They also showed preferential attraction to products infested with the new host over uninfested products. E. kuehniella was the preferred host, irrespectively of the parasitoid host rearing species. The results are discussed to develop a better understanding of the ecology of V. canescens for its application in biological control.     

Linkage analysis and identification of quantitative trait loci associated with freeze tolerance and turf quality traits in St. Augustinegrass

St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is a warm-season turfgrass commonly grown in the southern USA. In this study, the first linkage map for all nine haploid chromosomes of the species was constructed for cultivar ‘Raleigh’ and cultivar ‘Seville’ using a pseudo-F₂ mapping strategy. A total of 160 simple sequence repeat markers were mapped to nine linkage groups (LGs) covering a total distance of 1176.24 cM. To demonstrate the usefulness of the map, quantitative trait loci (QTL) were mapped controlling field winter survival, laboratory-based freeze tolerance, and turf quality traits. Multiple genomic regions associated with these traits were identified. Moreover, overlapping QTL were found for winterkill and spring green up on LG 3 (99.21 cM); turf quality, turf density, and leaf texture on LG 3 (68.57–69.50 cM); and surviving green tissue and regrowth on LGs 1 (38.31 cM), 3 (77.70 cM), 6 (49.51 cM), and 9 (34.20 cM). Additional regions, where QTL identified in both field and laboratory-based/controlled environment freeze testing co-located, provided strong support that these regions are good candidates for true gene locations. These results present the first complete linkage map produced for St. Augustinegrass, providing a template for further genetic mapping. Additionally, markers linked to the QTL identified may be useful to breeders for transferring these traits into new breeding lines and cultivars.     

Identificación de polimorfismos de un solo nucleótido relacionados con la fragilidad

Introduction

The search for biomarkers that can lead to the early diagnosis and thus, early treatment of frailty, has become one of the main challenges facing the geriatric scientific community. The aim of the present study was to identify single nucleotide polymorphisms (SNPs) related to frailty.