Membranas de polisulfona/poliuretano foram preparadas pelo método de inversão de fases. As membranas preparadas com a adição de fotoiniciador foram irradiadas com lâmpada ultravioleta para aumentar a interação entre os polímeros e o suporte de poliéster utilizado. As membranas com e sem adição de fotoiniciador foram caracterizadas através dos testes de resistência química, capacidade de adsorção de água, determinação de densidade, porosidade, morfologia e fluxo permeado de água. A membrana fotoiniciada apresentou poros com paredes bem definidas e maior estabilidade nos testes de resistência química e fluxo permeado. Ambas as membranas apresentaram valores aproximados na adsorção de água e porosidade.

Polysulfone/polyurethane membranes were prepared by the phase inversion method and irradiated with an ultraviolet light bulb to increase the interaction between polymers and the polyester support. The membranes with and without addition of fotoinitiator were characterized using tests of chemical resistance, water adsorption capacity, density and porosity determination, water permeate flux and membrane morphology. The membrane treated with the fotoinitiator exhibited well defined pores and greater stability in the tests of chemical resistance and water permeate flux. Both membranes had similar values for the water adsorption and porosity.

Actin-encoding cDNAs of Nile tilapia (Oreochromis niloticus) were isolated by RT-PCR using total RNA samples of different tissues and further characterized by nucleotide sequencing and in silico amino acid (aa) sequence analysis. Comparisons among the actin gene sequences of O. niloticus and those of other species evidenced that the isolated genes present a high similarity to other fish and other vertebrate actin genes. The highest nucleotide resemblance was observed between O. niloticus and O. mossambicus a-actin and b-actin genes. Analysis of the predicted aa sequences revealed two distinct types of cytoplasmic actins, one cardiac muscle actin type and one skeletal muscle actin type that were expressed in different tissues of Nile tilapia. The evolutionary relationships between the Nile tilapia actin genes and diverse other organisms is discussed.

An alpha actin gene segment, isolated from Nile tilapia (Oreochromis niloticus), was characterized by nucleotide sequencing, predicted amino acid sequence and Southern blot hybridization. Genomic DNA amplification resulted in a 1063-bp fragment corresponding to a partial alpha-cardiac muscle actin gene containing exons 3 to 6. Southern blot analysis of the restriction-digested DNA revealed that the Nile tilapia genome contains multiple muscle actin isoforms. Although comparison of the nucleotide sequence, amino acid residues and exon-intron organization of the isolated actin gene with those of other vertebrates showed a high level of identity, diagnostic amino acid residues can still be correlated to distinct actin genes in fish species.