Lisina digestível para frangos de corte machos entre 12 e 22 dias de idade / Digestible lysine for male broilers from 12 to 22 days of age

Avaliou-se nível de lisina digestível para 1050 frangos de corte dos 12 aos 22 dias de idade. O delineamento experimental foi inteiramente ao acaso, com cinco tratamentos, sete repetições e 30 aves por unidade experimental. Os tratamentos foram: 1,05; 1,10; 1,15; 1,20 e 1,25 por cento de lisina digestível. Avaliaram-se ganho de peso, consumo de ração, conversão alimentar, composição e deposição de nutrientes corporais. Foram constatados efeitos quadráticos de lisina digestível no consumo de ração e resposta linear ascendente no peso da carcaça. Na composição química da carcaça, houve resposta quadrática do nível de lisina na concentração de proteína. As taxas de deposição proteica, deposição de água, da carcaça e do corpo total tiveram aumento linear em resposta ao acréscimo de lisina na dieta. O aumento da concentração de lisina, todavia, coincidiu com a redução da matéria mineral nas vísceras e sangue e no corpo total. Considerado o desempenho, o nível 1,1 por cento de lisina digestível atendeu às necessidades do frango de corte entre o 12º e o 22º dia de idade. Consideradas a composição química e as taxas de deposição dos nutrientes corporais, a demanda pelo aminoácido digestível torna-se igual ou maior que 1,25 por cento.

The lysine level was evaluated for 1,050 male broilers from 12 to 22 days of age. The experimental design was completely randomized with five treatments, seven replications, and 30 birds per experimental unit. The treatments were: 1.05, 1.10, 1.15, 1.20, and 1.25 percent of digestible lysine. Weight gain, feed intake, feed: gain ratio, body composition, and nutrient deposition were measured. There were quadratic effects of digestible lysine on feed intake and an ascendant linear effect on carcass weight. In the carcass chemical composition, there was a quadratic response of lysine level in protein concentration. The deposition rates in carcass protein, carcass water, and whole body had a linear increase as response to lysine addition to diet. The lysine level increase however coincided with the mineral decrease on blood, offal, and whole body. Basing on performance, the digestible lysine 1.1 percent level attended the broiler needs from 12 to 22 days of age. On the other hand, considering the chemical composition and the nutrient accretion rates, the need for digestible amino acid was equal or higher than 1.25 percent.

Are high-lysine cereal crops still a challenge?

The essential amino acids lysine and threonine are synthesized in higher plants via a pathway starting with aspartate that also leads to the formation of methionine and isoleucine. Lysine is one of most limiting amino acids in plants consumed by humans and livestock. Recent genetic, molecular, and biochemical evidence suggests that lysine synthesis and catabolism are regulated by complex mechanisms. Early kinetic studies utilizing mutants and transgenic plants that over-accumulate lysine have indicated that the major step for the regulation of lysine biosynthesis is at the enzyme dihydrodipicolinate synthase. Despite this tight regulation, recent strong evidence indicates that lysine catabolism is also subject to control, particularly in cereal seeds. The challenge of producing crops with a high-lysine concentration in the seeds appeared to be in sight a few years ago. However, apart from the quality protein maize lines currently commercially available, the release of high-lysine crops has not yet occurred. We are left with the question, is the production of high-lysine crops still a challenge?.

Produccion de l-lisina por celulas en no crecimiento de Corynebacterium glutamicum / L-lysine production by corynebacterium glutamicum non growing cells

Los efectos estrógenos y la progesterona en el control endocrino de las funciones sexuales son bien conocidos. Sin embargo, su papel en el control de áreas extrahipotalámicas ha sido poco estudiado. Trabajos previos realizados en nuestro laboratorio demuestran que el 17 Beta-Estradiol tiene un efecto inhibitorio en la transmisión cortico-caudado. En el presente trabajo se exploraron los efectos de la inyección intravenosa de 17 alpha-Hidroxi-Progesterona sobre esta misma conexión. Ratas hembras intactas, hembras ovariectomizadas y machos intactos, de la variedad Sprague Dawley, de 250 a 300 g de peso, fueron anestesiadas con Hidrato de Cloral (40 mg/100 g; i.p.). La hormona se administró a través de um catéter colocado en la vena yugular derecha (10 mul; 2,5 mg/ml). Se usaron métodos electrofisiológicos convencionales, utilizando electrodos de vidrio para el registro de las respuestas en el Caudado y electrodos metálicos para la estimulacióncortical, aislados excepto en la punta. Las respuestas excitatorias fueron analizadas por una computadora, integrando barridos sucessivos para construir histogramas post-estímulos. La administración de la 17 alpha-Hidroxi-Progesterona produjo un aumento significativo de las respustas en la mayoría de las células (95 por ciento). En algunas células (35 por ciento), este aumento fue acompañado de una disminución también significativa. En una sola neurona la respuesta excitatoria disminuyó. Los cambios descritos se observaron a partir de los primeros 5-10 minutos después de la administración hormonal, y se prolongan por una hora o más, luego de lo cual se observa recuperación de la respuesta inicial. Los resultados demuestran que la 17 alpha-Hidroxi-Progesterona estimula la transmisión cortico-caudado en la rata. La corta latencia de estos efectos hace suponer que pueden estar mediados por mecanismos no genómicos.

Microbial production of L-lysine: a review.

Microbial production of L-lysine has been reviewed with 251 references. The review includes different lysine producing microorganisms, their optimum cultural conditions, yield, assay and process of product recovery. It includes a discussion on the pathway of aspartate family of amino acid's biosynthesis in bacteria and its regulation. Achievements in this regard made through genetic engineering have also been included.