Pereira J.R.,Embrapa Cotton |
Duarte A.E.,Regional University of Cariri |
Pitombeira J.B.,Federal University of Ceara |
da Silva M.A.P.,Regional University of Cariri |
And 2 more authors.
Phyton | Year: 2013
An experiment was conducted in dryland conditions of the Brazilian Northeast to determine the number of viable weed seeds (seedbank) in an upland cotton crop, and its distribution in the soil profile, before and after using various herbicide treatments. A randomized block design in a split-plot block scheme with 6 replications was used, where the main plots were constituted by a factorial (13 treatments and 2 sampling soil depths), and the subplots by 2 sampling dates. Te seedbank was determined by germination of the recovered weed seeds obtained from different soil depths. Te highest number of viable weed seeds in the area was found before the application of the herbicide treatments at 0 - 10 cm soil depth. Te treatments metalachlor + diuron; diuron + pendimethalin and the control (no herbicide treatment, weeded weekly during the entire cotton crop cycle) were the most effective in reducing the weed seed-bank in the area.
Lucena W.A.,Embrapa Cotton |
Lucena W.A.,Federal University of Rio Grande do Sul |
Pelegrini P.B.,Embrapa Genetic Resources and Biotechnology |
Martins-de-Sa D.,Embrapa Genetic Resources and Biotechnology |
And 12 more authors.
Toxins | Year: 2014
Bacillus thuringiensis (Bt) is a gram-positive spore-forming soil bacterium that is distributed worldwide. Originally recognized as a pathogen of the silkworm, several strains were found on epizootic events in insect pests. In the 1960s, Bt began to be successfully used to control insect pests in agriculture, particularly because of its specificity, which reflects directly on their lack of cytotoxicity to human health, non-target organisms and the environment. Since the introduction of transgenic plants expressing Bt genes in the mid-1980s, numerous methodologies have been used to search for and improve toxins derived from native Bt strains. These improvements directly influence the increase in productivity and the decreased use of chemical insecticides on Bt-crops. Recently, DNA shuffling and in silico evaluations are emerging as promising tools for the development and exploration of mutant Bt toxins with enhanced activity against target insect pests. In this report, we describe natural and in vitro evolution of Cry toxins, as well as their relevance in the mechanism of action for insect control. Moreover, the use of DNA shuffling to improve two Bt toxins will be discussed together with in silico analyses of the generated mutations to evaluate their potential effect on protein structure and cytotoxicity. © 2014 by the authors; licensee MDPI, Basel, Switzerland.
Bezerra C.A.,Catholic University of Brasilia |
Macedo L.L.P.,Catholic University of Brasilia |
Amorim T.M.L.,Federal University of Rio Grande do Norte |
Santos V.O.,Federal University of Rio Grande do Norte |
And 8 more authors.
Gene | Year: 2014
α-Amylases are common enzymes responsible for hydrolyzing starch. Insect-pests, whose larvae develop in seeds, rely obligatorily on α-amylase activity to digest starch, as their major food source. Considering the relevance of insect α-amylases and the natural α-amylase inhibitors present in seeds to protect from insect damage, we report here the molecular cloning and nucleotide sequence of the full-length AmyHha cDNA of the coffee berry borer, Hypothenemus hampei, a major insect-pest of coffee crops. The AmyHha sequence has 1879. bp, containing a 1458. bp open reading frame, which encodes a predicted protein with 485 amino acid residues, with a predicted molecular mass of 51.2. kDa. The deduced protein showed 55-79% identity to other insect α-amylases, including Anthonomus grandis, Ips typographus and Sitophilus oryzae α-amylases. In depth analysis revealed that the highly conserved three amino acid residues (Asp184, Glu220, and Asp285), which compose the catalytic site are also presented in AmyHha amylase. The AmyHha gene seems to be a single copy in the haploid genome and AmyHha transcription levels were found higher in L2 larvae and adult insects, both corresponding to major feeding phases. Modeling of the AmyHha predicted protein uncovered striking structural similarities to the Tenebrio molitor α-amylase also displaying the same amino acid residues involved in enzyme catalysis (Asp184, Glu220 and Asp285). Since AmyHha gene was mostly transcribed in the intestinal tract of H. hampei larvae, the cognate α-amylase could be considered a high valuable target to coffee bean insect control by biotechnological strategies. © 2014 The Authors.
Nascimento D.M.D.,Federal University of Ceara |
Almeida J.S.,State University of Ceara |
Vale M.D.S.,Embrapa Tropical Agroindustry |
Leitao R.C.,Embrapa Tropical Agroindustry |
And 4 more authors.
Industrial Crops and Products | Year: 2015
The high lignin content in the unripe coconut fiber limits the use of this biomass as a cellulose nanocrystal source compared to other cellulose-rich materials. The aim of this study was to obtain lignin and biomethane, and evaluate different approaches for extracting cellulose nanocrystal from unripe coconut coir fiber. The environmental evaluation of these approaches is presented in the second part of this paper. Lignin was extracted by acetosolv pulping and cellulose by alkaline hydrogen peroxide bleaching respectively. Were evaluated the biochemical methane potential of the effluents resulting from acetosolv pulping as well as the lignin concentration. Cellulose nanocrystals were prepared from cellulose pulp via four methods: acidic hydrolysis with high acid concentration, acidic hydrolysis with low acid concentration, ammonium persulfate oxidation, and high-power ultrasound. The cellulose nanocrystals were analyzed by FTIR spectroscopy, X-ray diffraction, transmission electron microscopy, and TG analysis. Using these methods, the whole coconut fiber could be used to produce cellulose nanocrystals and lignin. Among the proposed methods, high-power ultrasound showed the highest efficiency in cellulose nanocrystal extraction. © 2016 Elsevier B.V.
Alves T.J.S.,Federal University of Pernambuco |
Wanderley-Teixeira V.,Federal University of Pernambuco |
Teixeira A.A.C.,Federal University of Pernambuco |
Silva-Torres C.S.A.,Federal University of Pernambuco |
And 4 more authors.
Animal Biology | Year: 2014
Parasitoids have evolved mechanisms to evade their hosts' defenses. Bracon vulgaris (Ashmead) is a larval ectoparasitoid responsible for natural reduction of Anthonomus grandis (Boheman) and Pectinophora gossypiella (Saunders), which are considered the main cotton pests in the cotton agroecosystem in northeastern Brazil. This study aimed to analyze the sensory structures (antennae and ovipositor) involved in the parasitism behavior of B. vulgaris, and to describe and evaluate associations between composition, morphology, and functions of these structures in the parasitoid-host interaction. Results showed that the B. vulgaris ovipositor is a multifunctional structure of 2.7 ± 0.3 mm in length composed of 3 valves. Valves 1 and 2 are elongated, rigid, and act jointly to pierce the host's cuticle, to inject the poison glands secretion, and to deposit eggs. Valve 3 covers the other valves, giving them protection. Valve 3 also presents annulations in all its extension, which gives flexibility to the ovipositor, and trichoid sensilla that possibly capture vibrations from the host's feeding and locomotion, thereby aiding the parasite in the host selection. The presence of cuticular microtrichia was possibly responsible for the cleaning of the ovipositor, keeping it functional between the various insertions that occur during the parasitism behavior. The parasitoid's antennae are filliform-like, measure about 2 mm, and are composed of four types of sensilla (trichoids, basiconical, coeloconical, and placodes) that act as olfactory and gustatory receptors and/or express tactile, thermo,- and hygroreceptionfunctions. The integrated action of these sensory components corroborates the successful parasitism behavior of the parasitoid B. vulgaris. © 2014 Koninklijke Brill NV, Leiden.