Analysis of DNA damage induced by aflatoxin B1 in Dunkin–Hartley guinea pigs

Aflatoxin B1 (AFB1) is among the most potent naturally occurring carcinogens and classified as a group I carcinogen. Since the ingestion of aflatoxin-contaminated food is associated with several liver diseases, the aim of the present study was to evaluate the effect of 2, 20, and 200 ppb of AFB1 on DNA damage in peripheral blood lymphocytes and liver cells in Dunkin-Hartley guinea pigs. The animals were divided into four groups according to the given diet. After the treatment the lymphocytes and liver cells were isolated and DNA damage determined by Comet assay. The levels of DNA damage in lymphocytes were higher animals treated with 200 ppb of AFB1-enriched diet (P = 0.02). In the liver cells there were a relationship between the levels of DNA damage and the consumption of AFB1 in all studied groups. These results suggest that Comet assay performed on lymphocytes is a valuable genotoxic marker for high levels of exposure to AFB1 in guinea pig. Additionally our results indicate that the exposure to this toxin increases significantly and increases the level of DNA damage in liver cells, which is a key step on liver cancer development. We also suggest that the Comet assay is an useful tool for monitoring the genotoxicity of AFB1 in liver.     

First description of the immature stages of Hemilucilia segmentaria (Diptera: Calliphoridae)

The immature stages oí Hemilucilia segmentaria (Fabricius, 1805) (Diptera: Calliphoridae) are described. Egg morphology and structures such as the cephalopharyngeal skeleton, anterior and posterior spiracles, and the dorsal spines between the prothorax and mesothorax from first, second and third instar larvae are characterized, using light and scanning electron microscopy. This species is abundant in Neotropical forests and, because of its necrophagous behavior, is of substantial medico-legal importance for estimating the postmortem interval in criminal investigations. Information presented herein may be useful to differentiate among eggs and larvae of closely related species and to supplement the database for blowfly identification.     

Inferring the microscopic surface energy of protein–protein interfaces from mutation data

Mutations at protein–protein recognition sites alter binding strength by altering the chemical nature of the interacting surfaces. We present a simple surface energy model, parameterized with empirical values, yielding mean energies of ?48 cal mol^?1 Å^?2 for interactions between hydrophobic surfaces, ?51 to ?80 cal mol^?1 Å^?2 for surfaces of complementary charge, and 66–83 cal mol^?1 Å^?2 for electrostatically repelling surfaces, relative to the aqueous phase. This places the mean energy of hydrophobic surface burial at ?24 cal mol^?1 Å^?2. Despite neglecting configurational entropy and intramolecular changes, the model correlates with empirical binding free energies of a functionally diverse set of rigid‐body interactions (r = 0.66). When used to rerank docking poses, it can place near‐native solutions in the top 10 for 37% of the complexes evaluated, and 82% in the top 100. The method shows that hydrophobic burial is the driving force for protein association, accounting for 50–95% of the cohesive energy. The model is available open‐source from http://life.bsc.es/pid/web/surface_energy/ and via the CCharpPPI web server http://life.bsc.es/pid/ccharppi/ . Proteins 2015; 83:640–650. © 2015 Wiley Periodicals, Inc.     

Experimental management control of Opuntia dillenii Haw. and Agave americana L. in Teno Rural Park,Canary Islands

Invasion biology is an important element of global environmental change and represents one of the main threats to biodiversity. American species were introduced to Tenerife after the Spanish conquest during the eighteenth century, as is the case for Agave americana and Opuntia dillenii. The long period of naturalization and adaptation of these species has led them to become two of the most dispersed introduced species of the archipelago. We analyzed several eradication management processes in an area intensively invaded by both O. dillenii and A. americana. Three treatments were randomly applied: mechanical removal, use of herbicide (glyphosate at 10% volume), and mechanical and herbicide applied together. Both the effectiveness of the treatments to remove the target exotic species biovolume and the impact of the eradication methods on species richness and species composition of the area were analyzed. We found that the treatments had an impact on species composition but not on species richness. Species composition was mainly affected by mechanical treatment. The effect caused by the mechanical removal of the exotic target species in species composition is minor after 4 years, and is related to a higher dominance of shrub species typical of coastal shrubland and of annual or pioneer species. The control of O. dillenii and A. americana is evident from insignificant recovery 4 years after treatment application. A mechanical and herbicide treatment together, allowed not only the immediate removal of large individuals but also the herbicidal control of smaller ones.     

Multiple models for Rosaceae genomics

The plant family Rosaceae consists of over 100 genera and 3,000 species that include many important fruit, nut, ornamental, and wood crops. Members of this family provide high-value nutritional foods and contribute desirable aesthetic and industrial products. Most rosaceous crops have been enhanced by human intervention through sexual hybridization, asexual propagation, and genetic improvement since ancient times, 4,000 to 5,000 B.C. Modern breeding programs have contributed to the selection and release of numerous cultivars having significant economic impact on the U.S. and world markets. In recent years, the Rosaceae community, both in the United States and internationally, has benefited from newfound organization and collaboration that have hastened progress in developing genetic and genomic resources for representative crops such as apple (Malus spp.), peach (Prunus spp.), and strawberry (Fragaria spp.). These resources, including expressed sequence tags, bacterial artificial chromosome libraries, physical and genetic maps, and molecular markers, combined with genetic transformation protocols and bioinformatics tools, have rendered various rosaceous crops highly amenable to comparative and functional genomics studies. This report serves as a synopsis of the resources and initiatives of the Rosaceae community, recent developments in Rosaceae genomics, and plans to apply newly accumulated knowledge and resources toward breeding and crop improvement.     

BiSearch: primer-design and search tool for PCR on bisulfite-treated genomes

Bisulfite genomic sequencing is the most widely used technique to analyze the 5-methylation of cytosines, the prevalent covalent DNA modification in mammals. The process is based on the selective transformation of unmethylated cytosines to uridines. Then, the investigated genomic regions are PCR amplified, subcloned and sequenced. During sequencing, the initially unmethylated cytosines are detected as thymines. The efficacy of bisulfite PCR is generally low; mispriming and non-specific amplification often occurs due to the T richness of the target sequences. In order to ameliorate the efficiency of PCR, we developed a new primer-design software called BiSearch, available on the World Wide Web. It has the unique property of analyzing the primer pairs for mispriming sites on the bisulfite-treated genome and determines potential non-specific amplification products with a new search algorithm. The options of primer-design and analysis for mispriming sites can be used sequentially or separately, both on bisulfite-treated and untreated sequences. In silico and in vitro tests of the software suggest that new PCR strategies may increase the efficiency of the amplification.     

Parasitoid wasp affects metabolism of cockroach host to favor food preservation for its offspring

Unlike predators, which immediately consume their prey, parasitoid wasps incapacitate their prey to provide a food supply for their offspring. We have examined the effects of the venom of the parasitoid wasp Ampulex compressa on the metabolism of its cockroach prey. This wasp stings into the brain of the cockroach causing hypokinesia. We first established that larval development, from egg laying to pupation, lasts about 8 days. During this period, the metabolism of the stung cockroach slows down, as measured by a decrease in oxygen consumption. Similar decreases in oxygen consumption occurred after pharmacologically induced paralysis or after removing descending input from the head ganglia by severing the neck connectives. However, neither of these two groups of cockroaches survived more than six days, while 90% of stung cockroaches survived at least this long. In addition, cockroaches with severed neck connectives lost significantly more body mass, mainly due to dehydration. Hence, the sting of A. compressa not only renders the cockroach prey helplessly submissive, but also changes its metabolism to sustain more nutrients for the developing larva. This metabolic manipulation is subtler than the complete removal of descending input from the head ganglia, since it leaves some physiological processes, such as water retention, intact.     

Disruption of microtubular network attenuates histamine-induced dilation in rat mesenteric vessels

Cytoplasmic microtubules are important in many cellular homeostatic processes in the cell. They regulate cell shape and movement as well as serving as a network by which vesicles and membrane-bound organelles can travel. Lately, there have been many studies demonstrating that microtubules are involved in regulation of intracellular signaling and, therefore, affect vascular reactivity. In this study, we tested the hypothesis that microtubule disruption attenuates agonist-induced endothelium-dependent vasodilation. Isolated mesenteric arterial bed from normotensive rats was preconstricted with phenylephrine, and dose-response curves for histamine, acetylcholine (ACh), sodium nitroprusside (SNP), and pinacidil were performed before and after incubation with nocodazole or colchicine. Treatment of the vascular beds with nocodazole or colchicine significantly attenuated histamine relaxation but did not change the ACh-, SNP-, or pinacidil-induced vasorelaxation. Nocodazole did not cause an additional attenuation of the histamine-mediated dilation in mesenteric vessels in the presence of N-nitro-L-arginine methyl ester, high extracellular K⁺, or K⁺ channel blockers. These data suggest that disruption of microtubules affects an essential endothelial component of histamine-mediated vasodilation in the mesenteric arterial bed. The mechanism(s) involved in this effect might be related to an impairment of endothelial NO synthesis, which might not be as important for the ACh as for the histamine vasodilator response in rat mesenteric vessels. These results demonstrate the importance of the microtubular system for endothelium-dependent NO-mediated smooth muscle relaxation. nocodazole; nitric oxide; mesenteric arterial bed     

Axonal growth: where neurotrophins meet Wnts

Axonal guidance is influenced by many cues, including polypeptide trophic factors, cytokines, diffusible attractants and repellents and changes in calcium. How these signals are conveyed and integrated is not well defined. Recent data suggest that molecules of the canonical Wnt signaling pathway may have direct actions on axonal growth through neurotrophin signaling. This surprising mechanism is supported by local inactivation of glycogen synthase kinase 3beta (GSK-3beta) by nerve growth factor through the integrin-linked kinase. Inhibition of GSK-3beta provides a positive regulatory signal for the cytoskeleton re-arrangement involved in axon extension. Moreover, microtubule stabilization is stimulated by adenomatous polyposis coli protein, a downstream target of GSK3, in response to neurotrophins. Therefore, components of the Wnt signaling pathway are downstream of trophic factors, providing new insights into cytoskeletal regulatory events during axonal growth.     

Cu(II) complex formation with xylitol in alkaline solutions

The formation of four Cu(II)-xylitol complexes was observed in aqueous alkaline solutions (11.0< or =pH< or =14.0, I=1.0, 20 degrees C) by means of direct current polarography and VIS spectrophotometry. Mononuclear hydroxy complexes, CuXyl(OH)- (log beta=17.7 +/- 0.5), CuXyl(OH)2(2-) (log beta=20.2 +/- 0.3) and CuXyl2(OH)2(4-) (log beta=22.4 +/- 0.3), are formed at high ligand-to-metal ratios (L:M> or =10), whereas dinuclear complex Cu2Xyl (log beta=29.2 +/- 0.3) is the predominant species at low ligand-to-metal ratio (L:M=0.5). Diffusion coefficients and molar absorptivities of the complex species were determined. pH variable 13C NMR suggested that pKa values of xylitol are rather similar and equal to 13.8 +/- 0.2, 13.9 +/- 0.1 and 13.9 +/- 0.2 for OH-groups adjacent to (C-1,C-5), (C-3) and (C-2,C-4) carbon atoms, respectively.