A new tetra-primer ARMS-PCR for genotyping bovine kappa-casein polymorphisms

[EN] Kappa-casein (κ-casein) is one of the most abundant milk proteins. Its main function is to avoid the aggregation of casein micelles, keeping them, and therefore calcium phosphate, in pockets in solution. In bovines, a κ-casein functional polymorphism has been associated with fat, calcium, and protein milk contents and faster curd contraction in cheese production. Quicker curd contraction reduces the loss of milk solids, enhancing cheese yield. This polymorphism induces a double amino acid substitution (Thr136Ile and Ala148Asp). The polymorphism is normally detected by PCR-RFLP, which is a laborious method. An interesting methodological alternative is the tetra-primer amplification refractory mutation system PCR (tetra-primer ARMS-PCR). A tetra-primer ARMS-PCR for the detection of this κ-casein polymorphism has been described. However, specificity was not achieved, probably due to problems with primer design. We developed a new tetra-primer ARMS-PCR for the detection of the κ-casein polymorphism. This new method was validated in a double-blind test, by comparison with the results obtained for 50 Guzerá bulls formerly genotyped by PCR-RFLP. This new method achieved 100% sensitivity and specificity. We conclude that this method is a useful, cost-efficient alternative for the detection of functional κ-casein polymorphismsSIResearch supported by Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), Conselho Nacional de Pesquisa (CNPq), Pró-Reitoria de Pesquisa de Universidade Federal de Minas gerais (PRPq/UFMG), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). MRSC, PASF, MAM, and RSV have CNPq fellowships. IRC has a CAPES fellowship. We are grateful to Professor Vânia Maldini Pena and Ms. Ariane Figueiredo Menicucci from Colégio Brasileiro de Criadores do Guzerá, for providing biological sample

Effect of several calcium sources on cation leaching using soil columns

Soil columns under controlled conditions were used to determine the movement of calcium and other cations after the application of lime, calcium oxide, gypsum and a mixture of Ume and gypsum, compared with a control treatment. Two Oxisols with different textures were used: clayey and silty. Rigid polyvinyl chloride (PVC) columns (length, 45cm; diam, 5cm) were used, applying 1.8 1 of water to each divided into four applications. Exchangeable cations were determined in the drainage water in 4 periods and in 5 dephts of the soil columns at the end of the experiment. The results showed that losses of Ca2+, Mg2+, K+ and A1(3+), were higher in the treatments with gypsum and lime plus gypsum. Amendments h'ke lime and calcium oxide did not promote significant losses of cations. Large losses occured in the silty and clayey soils in the first and second drainage times respectively. Gypsum did not modify the pH of both soils, but reduced cation amounts mainly in the clayey soil. Lime and calcium oxide raised the pH only near the application layer.No estudo realizado em colunas de solo montadas em laboratório, procurou-se avaliar o movimento do cálcio, e de outros cátions, após aplicação de calcário agrícola, gesso, calcário calcinado e uma mistura de calcário agrícola e gesso, comparados com um tratamento testemunha, em dois latossolos vermelho escuros de texturas diferentes: média e argilosa. Utilizaram-se colunas de PVC, com 5cm de diâmetro e 45cm de altura, e aplicaram-se em cada coluna 1,8 litros de água, parcelados em quatro vezes. Determinaram-se os cátions trocáveis presentes na água percolada e, no final do experimento, em cinco profundidades de cada solo. Os resultados mostraram que nos tratamentos gesso e calcário mais gesso as quantidades de Ca2+, Mg2+, K+ e Al3+ na solução percolada foram maiores, enquanto que os tratamentos calcário agrícola e calcário calcinado não promoveram perdas significativas de cátions. As maiores perdas ocorreram na primeira percolação no solo de textura média e na segunda no solo de textura argilosa. O gesso não modificou o pH dos solos, mas reduziu teores de bases no solo argiloso, enquanto que os calcários corrigiram o solo apenas próximo à camada de incorporação

Estudos sobre a nutrição mineral do arroz: XXV. Exigências nutricionais da variedade Dourado Precoce

Rice plants, Dourado Precoce, were grown in nutrient solution in order to study its nutritional requirement as well as the accumulation of dry matter and macro and micronutrients (excet Mo) during the life cycle. Demand for mineral elements followed the following decreasing order: macronutrients -K, N, Ca, Mg and S; micronutrients - Fe, Mn, Cu, Zn and B. Dry matter yield reached a maximun 100 days after germination (DAG), whereas accumulation of elements showed the geghest values at largest (140 DAG).Em condições de solução nutritiva foi cultivado o arroz Dourado Precoce com a finalidade de se estudar a marcha de absorção de nutrientes e as exigências minerais. Verificou-se que as exigências minerais obedecem a seguinte ordem decrescente: macronutrientes -K, N, Ca, Mg e S; micronutrientes -Fe, Mn, Cu, Zn e B. A produção de matéria seca atingiu o pico aos 100 dias após a germinação (DAG). A acumulação de macro e micronutrientes na planta foi, entretanto, máxima no fim do ciclo (140 DAG)

Soil cover plants on water erosion control in the South of Minas Gerais

Water erosion is responsible for soil, water, carbon and nutrient losses, turning into the most important type of degradation of Brazilian soils. This study aimed to evaluate the influence of three cover plants under two tillage systems on water erosion control in an Argisol at south of Minas Gerais state, Brazil. The cover plants utilized in the study were pigeon pea, jack bean and millet, under contour seeding and downslope tillage. Experimental plots of 4 x 12 m, with 9% slope, under natural rainfall were used for the quantification of losses of soil, water, nutrients, and organic matter. One experimental plot was kept without plant cover (reference). Higher erosivity was observed in December and January, although a great quantity of erosive rainfall was detected during the whole raining period. Contour seeding provided a greater reduction of water erosion than downslope tillage, as expected. The jack bean under contour seeding revealed the lowest values of soil, water, nutrients and organic matter losses