Efficacy test of a hydrolysable tannin extract against necrotic enteritis in challenged broiler chickens

A hydrolysable tannin extracted from chestnut (SaviotaN®) was tested for efficacy in controlling the proliferation of Clostridium perfringens in the gut of broiler chickens challenged via oral gavage first with coccidia (Eimeria tenella, Eimeria acervulina, Eimeria maxima) at the age of 10 days, and then with Clostridium perfringens at the age of 15 days. We randomly allocated 150 broiler chickens within 5 poultry isolators (30 birds each). Dietary treatments consisted of a basal diet (C) composed of corn [575 g/kg on dry matter (DM)] and soybean meal (100 g/kg DM), barley bran (220 g/kg DM), corn gluten feed (30 g/kg DM), soybean oil (25 g/kg DM), vitamin mineral premix (49.5 g/kg DM), and four other diets obtained by adding chestnut tannin extract (1.5, 3, 5, and 12 g/kg during week 1, 10.0 g/kg during week 2, and 8.0 g/kg during the last two weeks, respectively) to C. At the age of 20 days, 15 birds/group were euthanised and individually examined for the level of gut infection by count- ing Clostridium perfringens and macroscopic gut lesions. Results demonstrated that chestnut tan- nin gave significant results even at low concen- tration levels in the feed (1.5 to 3.0 g/kg), but was actually efficient in controlling necrotic enteritis at levels ≥5.0 g/kg. The treatment (12.0 g/kg dur- ing the first week and 8.0 g/kg during the last two weeks of age) resulted very efficient in control- ling the proliferation of Clostridium perfringens and in reducing the severity of gut damage com- pared to the untreated infected group

Non-specific protein-DNA interactions control I-CreI target binding and cleavage

Homing endonucleases represent protein scaffolds that provide powerful tools for genome manipulation, as these enzymes possess a very low frequency of DNA cleavage in eukaryotic genomes due to their high specificity. The basis of protein-DNA recognition must be understood to generate tailored enzymes that target the DNA at sites of interest. Protein-DNA interaction engineering of homing endonucleases has demonstrated the potential of these approaches to create new specific instruments to target genes for inactivation or repair. Protein-DNA interface studies have been focused mostly on specific contacts between amino acid side chains and bases to redesign the binding interface. However, it has been shown that 4 bp in the central DNA sequence of the 22-bp substrate of a homing endonuclease (I-CreI), which do not show specific protein-DNA interactions, is not devoid of content information. Here, we analyze the mechanism of target discrimination in this substrate region by the I-CreI protein, determining how it can occur independently of the specific protein-DNA interactions. Our data suggest the important role of indirect readout in this substrate region, opening the possibility for a fully rational search of new target sequences, thus improving the development of redesigned enzymes for therapeutic and biotechnological applications

Vibrating Circular Membrane

The Bessel function of the first kind, Jn(z), can be used to model the motion of a vibrating membraneComponente Curricular::Educação Superior::Ciências Exatas e da Terra::Matemátic