Nitric oxide regulates adhesiveness, invasiveness, and migration of anoikis-resistant endothelial cells.

Anoikis is a type of apoptosis that occurs in response to the loss of adhesion to the extracellular matrix (ECM). Anoikis resistance is a critical mechanism in cancer and contributes to tumor metastasis. Nitric oxide (NO) is frequently upregulated in the tumor area and is considered an important player in cancer metastasis. The aim of this study was to evaluate the effect of NO on adhesiveness, invasiveness, and migration of anoikis-resistant endothelial cells. Here, we report that anoikis-resistant endothelial cells overexpress endothelial nitric oxide synthase. The inhibition of NO release in anoikis-resistant endothelial cells was able to decrease adhesiveness to fibronectin, laminin, and collagen IV. This was accompanied by an increase in cell invasiveness and migration. Furthermore, anoikis-resistant cell lines displayed a decrease in fibronectin and collagen IV protein expression after L-NAME treatment. These alterations in adhesiveness and invasiveness were the consequence of MMP-2 up-regulation observed after NO release inhibition. The decrease in NO levels was able to down-regulate the activating transcription factor 3 (ATF3) protein expression. ATF3 represses MMP-2 gene expression by antagonizing p53-dependent trans-activation of the MMP-2 promoter. We speculate that the increased release of NO by anoikis-resistant endothelial cells acted as a response to restrict the MMP-2 action, interfering in MMP-2 gene expression via ATF3 regulation. The up-regulation of nitric oxide by anoikis-resistant endothelial cells is an important response to restrict tumorigenic behavior. Without this mechanism, invasiveness and migration potential would be even higher, as shown after L-NAME treatment.

Nitric oxide regulates adhesiveness, invasiveness, and migration of anoikis-resistant endothelial cells

Anoikis is a type of apoptosis that occurs in response to the loss of adhesion to the extracellular matrix (ECM). Anoikis resistance is a critical mechanism in cancer and contributes to tumor metastasis. Nitric oxide (NO) is frequently upregulated in the tumor area and is considered an important player in cancer metastasis. The aim of this study was to evaluate the effect of NO on adhesiveness, invasiveness, and migration of anoikis-resistant endothelial cells. Here, we report that anoikis-resistant endothelial cells overexpress endothelial nitric oxide synthase. The inhibition of NO release in anoikis-resistant endothelial cells was able to decrease adhesiveness to fibronectin, laminin, and collagen IV. This was accompanied by an increase in cell invasiveness and migration. Furthermore, anoikis-resistant cell lines displayed a decrease in fibronectin and collagen IV protein expression after L-NAME treatment. These alterations in adhesiveness and invasiveness were the consequence of MMP-2 up-regulation observed after NO release inhibition. The decrease in NO levels was able to down-regulate the activating transcription factor 3 (ATF3) protein expression. ATF3 represses MMP-2 gene expression by antagonizing p53-dependent trans-activation of the MMP-2 promoter. We speculate that the increased release of NO by anoikis-resistant endothelial cells acted as a response to restrict the MMP-2 action, interfering in MMP-2 gene expression via ATF3 regulation. The up-regulation of nitric oxide by anoikis-resistant endothelial cells is an important response to restrict tumorigenic behavior. Without this mechanism, invasiveness and migration potential would be even higher, as shown after L-NAME treatment.

Caracterização nutricional das folhas de Moringa oleifera (MOL) para frangos de corte / Chemical and nutritional characterization of moringa oleifera leaves for broilers

Objetivou-se determinar os valores energéticos e nutricionais das folhas de Moringa oleifera (MOL) para frangos de corte. Utilizaram-se 90 pintos machos, Cobb-500, com 14 dias de idade, distribuídos em delineamento inteiramente ao acaso, com cinco tratamentos e seis repetições de três aves. Os tratamentos consistiram de: uma dieta referência e quatro dietas com substituição de 10%, 20%, 30% e 40% da dieta referência pelas folhas de MOL. O período experimental teve duração de oito dias, utilizando-se a metodologia de coleta total de excretas. Foram determinados os valores de energia metabolizável aparente (EMA), aparente corrigida para o nitrogênio (EMAn), coeficiente de metabolizabilidade aparente da matéria seca (CMAMS), da proteína bruta (CMAPB) e da energia bruta (CMAEB). Os resultados obtidos foram submetidos à análise de variância e à análise de regressão a 5% de probabilidade. Houve efeito quadrático das variáveis à medida que a moringa era adicionada à ração referência. Na derivação das equações de regressão, o nível que proporcionou os melhores valores de EMA, EMAn e CMEB foi de 37,7% de substituição. O farelo de folhas MOL apresentou médias de 3140kcal/kg de EMA, 2845kcal/kg de EMAn, 76,92% de CMAEB, 76,63% de CMAMS e 73,42% de CMAPB.(AU)

This study aimed to determine the energy and nutritional value of the leaves of Moringa oleifera (MOL) for broilers. We used 90 male chicks, Cobb-500, with 14 days of age in a completely randomized design with five treatments and six repetitions of three birds. The treatments were: reference diet and 4 diets with substitution of 10%, 20%, 30%, and 40% of the diet by reference sheet MOL. The trial lasted eight days, using the method of total excreta collection. The apparent metabolizable energy (AME), apparent corrected for nitrogen (AMEn), apparent metabolizable coefficient of dry matter (AMCDM), crude protein (AMCCP) and gross energy (AMCGE). The results were submitted to analysis of variance and regression analysis at 5% probability. There was a quadratic effect of the variables as the moringa was added to the reference diet. In the derivation of the regression equations the level that provided the best values of AME, AMEn, AMCGE was 37.7% substitution. The leaves meal MOL presented average 3140kcal / kg of AME, 2845kcal / kg AMEn, 76.92% of AMCGE, 76.63% of AMCDM and 73.42% of AMCCP.(AU)

Caracterização nutricional das folhas de Moringa oleifera (MOL) para frangos de corte / Chemical and nutritional characterization of moringa oleifera leaves for broilers

Objetivou-se determinar os valores energéticos e nutricionais das folhas de Moringa oleifera (MOL) para frangos de corte. Utilizaram-se 90 pintos machos, Cobb-500, com 14 dias de idade, distribuídos em delineamento inteiramente ao acaso, com cinco tratamentos e seis repetições de três aves. Os tratamentos consistiram de: uma dieta referência e quatro dietas com substituição de 10%, 20%, 30% e 40% da dieta referência pelas folhas de MOL. O período experimental teve duração de oito dias, utilizando-se a metodologia de coleta total de excretas. Foram determinados os valores de energia metabolizável aparente (EMA), aparente corrigida para o nitrogênio (EMAn), coeficiente de metabolizabilidade aparente da matéria seca (CMAMS), da proteína bruta (CMAPB) e da energia bruta (CMAEB). Os resultados obtidos foram submetidos à análise de variância e à análise de regressão a 5% de probabilidade. Houve efeito quadrático das variáveis à medida que a moringa era adicionada à ração referência. Na derivação das equações de regressão, o nível que proporcionou os melhores valores de EMA, EMAn e CMEB foi de 37,7% de substituição. O farelo de folhas MOL apresentou médias de 3140kcal/kg de EMA, 2845kcal/kg de EMAn, 76,92% de CMAEB, 76,63% de CMAMS e 73,42% de CMAPB.(AU)

This study aimed to determine the energy and nutritional value of the leaves of Moringa oleifera (MOL) for broilers. We used 90 male chicks, Cobb-500, with 14 days of age in a completely randomized design with five treatments and six repetitions of three birds. The treatments were: reference diet and 4 diets with substitution of 10%, 20%, 30%, and 40% of the diet by reference sheet MOL. The trial lasted eight days, using the method of total excreta collection. The apparent metabolizable energy (AME), apparent corrected for nitrogen (AMEn), apparent metabolizable coefficient of dry matter (AMCDM), crude protein (AMCCP) and gross energy (AMCGE). The results were submitted to analysis of variance and regression analysis at 5% probability. There was a quadratic effect of the variables as the moringa was added to the reference diet. In the derivation of the regression equations the level that provided the best values of AME, AMEn, AMCGE was 37.7% substitution. The leaves meal MOL presented average 3140kcal / kg of AME, 2845kcal / kg AMEn, 76.92% of AMCGE, 76.63% of AMCDM and 73.42% of AMCCP.(AU)

Coupling of vinculin to F-actin demands Syndecan-4 proteoglycan.

Syndecans are heparan sulfate proteoglycans characterized as transmembrane receptors that act cooperatively with the cell surface and extracellular matrix proteins. Syn4 knockdown was performed in order to address its role in endothelial cells (EC) behavior. Normal EC and shRNA-Syn4-EC cells were studied comparatively using complementary confocal, super-resolution and non-linear microscopic techniques. Confocal and super-resolution microscopy revealed that Syn4 knockdown alters the level and arrangement of essential proteins for focal adhesion, evidenced by the decoupling of vinculin from F-actin filaments. Furthermore, Syn4 knockdown alters the actin network leading to filopodial protrusions connected by VE-cadherin-rich junction. shRNA-Syn4-EC showed reduced adhesion and increased migration. Also, Syn4 silencing alters cell cycle as well as cell proliferation. Moreover, the ability of EC to form tube-like structures in matrigel is reduced when Syn4 is silenced. Together, the results suggest a mechanism in which Syndecan-4 acts as a central mediator that bridges fibronectin, integrin and intracellular components (actin and vinculin) and once silenced, the cytoskeleton protein network is disrupted. Ultimately, the results highlight Syn4 relevance for balanced cell behavior.

Energia metabolizável da levedura de cana-de-açúcar submetida a diferentes temperaturas e tempos de secagem para frangos de corte e poedeiras / Metabolizable energy of sugar cane yeast submitted to different temperatures and drying times for broilers and layers hens

Objetivou-se determinar a temperatura e o tempo de secagem por rolos rotativos, aos quais a, levedura de cana-de-açúcar é submetida que permitam seu melhor aproveitamento energético por galinhas poedeiras e frangos de corte. Para isso foram realizados três ensaios de metabolismo para determinar os valores de energia metabolizável aparente (EMA), aparente corrigida para nitrogênio (EMAn) e os coeficientes de metabolizabilidade aparente da matéria seca (CMMS) e da energia bruta (CMEB). O primeiro ensaio foi conduzido com galinhas poedeiras (E1), o segundo com frangos de corte (E2) em crescimento e o terceiro com frangos de corte em diferentes idades (E3). Nos ensaios E1 e E2 os tratamentos consistiram em uma dieta referência, milho e farelo de soja, e cinco dietas teste contendo 20% da levedura a ser testada em substituição à ração referência. As leveduras avaliadas foram secas por rolagem e submetidas aos seguintes processamentos: LevA - secagem a 107ºC por 107 segundos; LevB - 95ºC por 107'; LevC - 100ºC por 107'; LevD - 100ºC por 93' e LevE - 100ºC por 123'. No E3 determinou-se a EMA, EMAn, CMMS e CMEB da LevB com frangos de 1 a 8 dias, 14 a 22 dias e 28 a 36 dias de idade. No E1 não foram observadas diferenças nos valores de EMA, EMAn e CMEB entre as leveduras, com médias de 1.773kcal/kg, 1.733kcal/kg e 40,22%, respectivamente. Entretanto o CMMS foi maior para a LevD (50,36%). No E2 os valores de EMA (1.633kcal/kg), EMAn (1.382kcal/kg) e CMEB (32,22%) foram melhores para a LevB, porém não houve diferença significativa nos valores de CMMS (29,63%). No E3 foram encontrados valores de 2.723; 1.604 e 1.414kcal/kg para EMA; 2.366, 1.391 e 1.303kcal/kg para EMAn; 52,43%, 36,74%, e 25,64% para CMMS; e 54,37%, 33,49% e 24,96% para CMEB, nas idades de 1 a 8 dias, 14 a 22 dias e 28 a 36 dias, respectivamente. [...](AU)

This study aimed to determine the temperature and drying time through rotative rolls, that sugar cane yeast is subjected to in order to allow best energy utilization by laying hens and broilers. Three metabolism trials were conducted to determine the values of apparent metabolizable energy (AME) and apparent corrected for nitrogen balance (AMEn), coefficient of apparent metabolizable dry matter (CAMDM) and gross energy (CAMGE). The first experiment was conducted with laying hens (E1), the second with broilers (E2) in growth and the third with broilers at different ages (E3). In the experiments E1 and E2 the treatments consisted of a reference diet, based on corn and soybean meal, and five test diets containing 20% of the yeast to be tested. The evaluated yeasts were subjected to the following processes: Lev.A) drying at 107°C for 107 seconds; Lev.B) 95°C for 107'; Lev.C) 100ºC for 107'; Lev.D) 100°C for 93' and Lev.E) 100ºC for 123'. For the E3 group AME, AMEn, CAMDM and CAMGE were determined for the Lev.B of broilers with 1 to 8 days 14 to 22 days, and 28 to 36 days of age. In E1 there were no differences in AME, AMEn and CAMGE between yeasts, with mean of 1773kcal/kg 1733kcal/kg and 40.22%, respectively. However the CMMS was greater for Lev.D (50.36%). In E2, the AME (1633kcal/kg), AMEn (1382kcal/kg) and CAMGE (32.22%) were best for Lev.B, but there was no significant difference in the values of CAMMD (29 63%). TheE3 grouphad values of 2723kcal/kg; 1604kcal/kg and 1414kcal/kg of AME; 2366kcal/kg, 1391kcal/kg and 1303kcal/kg of AMEn; 52.43%, 36.74%, and 25.64% of CAMDM; and 54.37%, 33.49% and 24.96% of CAMGE, in the ages of 1 to 8 days, 14 to 22 days and 28 to 36 days, respectively. In conclusion, for layer hens, the yeast should be dried at 100°C for 93' or 107 seconds or 95ºC for 107' and for, broilers, it should be dried at 95°C for 107 seconds(AU)

Energia metabolizável da levedura de cana-de-açúcar submetida a diferentes temperaturas e tempos de secagem para frangos de corte e poedeiras / Metabolizable energy of sugar cane yeast submitted to different temperatures and drying times for broilers and layers hens

Objetivou-se determinar a temperatura e o tempo de secagem por rolos rotativos, aos quais a, levedura de cana-de-açúcar é submetida que permitam seu melhor aproveitamento energético por galinhas poedeiras e frangos de corte. Para isso foram realizados três ensaios de metabolismo para determinar os valores de energia metabolizável aparente (EMA), aparente corrigida para nitrogênio (EMAn) e os coeficientes de metabolizabilidade aparente da matéria seca (CMMS) e da energia bruta (CMEB). O primeiro ensaio foi conduzido com galinhas poedeiras (E1), o segundo com frangos de corte (E2) em crescimento e o terceiro com frangos de corte em diferentes idades (E3)...

This study aimed to determine the temperature and drying time through rotative rolls, that sugar cane yeast is subjected to in order to allow best energy utilization by laying hens and broilers. Three metabolism trials were conducted to determine the values of apparent metabolizable energy (AME) and apparent corrected for nitrogen balance (AMEn), coefficient of apparent metabolizable dry matter (CAMDM) and gross energy (CAMGE). The first experiment was conducted with laying hens (E1), the second with broilers (E2) in growth and the third with broilers at different ages (E3)...

Energy values of traditional ingredients and sugarcane yeast for laying hens

An experiment was conducted to determine the chemical composition and apparent metabolizable energy (AME) and apparent metabolizable energy corrected for nitrogen balance (AMEn) values of corn, soybean meal (SBM), soybean oil (SO) and sugarcane yeast (SY) (Saccharomyces cerevisiae). A metabolism trial was performed with 120 Dekalb White laying hens at 65 weeks of age, using the method of total excreta collection. Birds were housed in metabolism cages and distributed according to a completely randomized design into five treatments with, six replicates of four birds each. The experimental period consisted of four days of adaptation and four days of excreta collection. The experimental diets included: a reference diet based on corn and SBM and four test diets containing 40% corn, 30% SBM, 10% SO or 30 % SY. The chemical compositions of the tested ingredients, expressed on "as-is" basis were: 86.9, 87.29, 87.32 and 99.5% dry matter; and 3.51, 2.08, 99.31 and 0.03 ether extract for corn, SBM, SO and SY, respectively. Corn, SBM, and SO presented 7.33, 43.61 and 24.64% crude protein, and 0.58, 5.07 and 6.77% ash, respectively; and crude fiber contents of corn and SBM were, respectively, 2.24% and 3.56%. The following AME and AMEn (kcal/kg dry matter) values were obtained: 3,801 and 3,760 kcal/kg for corn, 2,640 and 2,557 kcal/kg for SBM, 8,952 and 8,866 kcal/kg for SO, and 1,023 and 925 kcal/kg for sugarcane yeast, respectively.(AU)

Energy values of traditional ingredients and sugarcane yeast for laying hens

An experiment was conducted to determine the chemical composition and apparent metabolizable energy (AME) and apparent metabolizable energy corrected for nitrogen balance (AMEn) values of corn, soybean meal (SBM), soybean oil (SO) and sugarcane yeast (SY) (Saccharomyces cerevisiae). A metabolism trial was performed with 120 Dekalb White laying hens at 65 weeks of age, using the method of total excreta collection. Birds were housed in metabolism cages and distributed according to a completely randomized design into five treatments with, six replicates of four birds each. The experimental period consisted of four days of adaptation and four days of excreta collection. The experimental diets included: a reference diet based on corn and SBM and four test diets containing 40% corn, 30% SBM, 10% SO or 30 % SY. The chemical compositions of the tested ingredients, expressed on "as-is" basis were: 86.9, 87.29, 87.32 and 99.5% dry matter; and 3.51, 2.08, 99.31 and 0.03 ether extract for corn, SBM, SO and SY, respectively. Corn, SBM, and SO presented 7.33, 43.61 and 24.64% crude protein, and 0.58, 5.07 and 6.77% ash, respectively; and crude fiber contents of corn and SBM were, respectively, 2.24% and 3.56%. The following AME and AMEn (kcal/kg dry matter) values were obtained: 3,801 and 3,760 kcal/kg for corn, 2,640 and 2,557 kcal/kg for SBM, 8,952 and 8,866 kcal/kg for SO, and 1,023 and 925 kcal/kg for sugarcane yeast, respectively.

EJ-ras oncogene transfection of endothelial cells upregulates the expression of syndecan-4 and downregulates heparan sulfate sulfotransferases and epimerase.

The EC rabbit endothelial cell line was transfected with the EJ-ras oncogene (EJ-ras EC). EJ-ras EC cells display over expression of the Ras oncogene, morphological changes and deregulation of the cell cycle, becoming more densely populated and serum-independent. In addition, EJ-ras-transfectant cells show higher levels of the syndecan-4 mRNA. In addition to the increase in the core protein, a parallel increase in the glycosylation of the syndecan-4 protein, a proteoglycan that bears heparan sulfate chains, also occurs. This increase is observed both for the heparan sulfate proteoglycan synthesized by the cells and for that secreted to the culture medium. This enhancement in heparan sulfate synthesis was observed through metabolic labeling of the cells, immunoprecipitation of syndecan-4 and heparitinases treatment. Furthermore, the EJ-ras-transfectant cells do not exhibit decreased synthesis of heparan sulfate during the G(1)-S phase transition, as observed for the parental cell line. Also, heparan sulfate synthesis is not stimulated by PMA as displayed by parental endothelial cells. Significant structural changes of heparan sulfate, such as decreased O-sulfation, were observed in the EJ-ras-transfected cells. Decreases in the mRNA levels of some enzymes (glucuronosyl C-5 epimerase, iduronosyl-2-O-sulfotransferase, glucosaminyl-6-O-sulfotransferase-1 and N-deacetylase/N-sulfotransferase-1), involved in the biosynthetic pathway of heparan sulfate, were also observed. The results suggest that overexpression of the EJ-ras oncogene alters the cell cycle, through signal transduction cascades, upregulates the expression of syndecan-4, and downregulates enzymes involved in the heparan sulfate biosynthesis related to chain modification, leading to the structural changes of the heparan sulfate syndecan-4 proteoglycan in endothelial cells.

Specific structural features of syndecans and heparan sulfate chains are needed for cell signaling.

The syndecans, heparan sulfate proteoglycans, are abundant molecules associated with the cell surface and extracellular matrix and consist of a protein core to which heparan sulfate chains are covalently attached. Each of the syndecan core proteins has a short cytoplasmic domain that binds cytosolic regulatory factors. The syndecans also contain highly conserved transmembrane domains and extracellular domains for which important activities are becoming known. These protein domains locate the syndecan on cell surface sites during development and tumor formation where they interact with other receptors to regulate signaling and cytoskeletal organization. The functions of cell surface heparan sulfate proteoglycan have been centered on the role of heparan sulfate chains, located on the outer side of the cell surface, in the binding of a wide array of ligands, including extracellular matrix proteins and soluble growth factors. More recently, the core proteins of the syndecan family transmembrane proteoglycans have also been shown to be involved in cell signaling through interaction with integrins and tyrosine kinase receptors.

Specific structural features of syndecans and heparan sulfate chains are needed for cell signaling

The syndecans, heparan sulfate proteoglycans, are abundant molecules associated with the cell surface and extracellular matrix and consist of a protein core to which heparan sulfate chains are covalently attached. Each of the syndecan core proteins has a short cytoplasmic domain that binds cytosolic regulatory factors. The syndecans also contain highly conserved transmembrane domains and extracellular domains for which important activities are becoming known. These protein domains locate the syndecan on cell surface sites during development and tumor formation where they interact with other receptors to regulate signaling and cytoskeletal organization. The functions of cell surface heparan sulfate proteoglycan have been centered on the role of heparan sulfate chains, located on the outer side of the cell surface, in the binding of a wide array of ligands, including extracellular matrix proteins and soluble growth factors. More recently, the core proteins of the syndecan family transmembrane proteoglycans have also been shown to be involved in cell signaling through interaction with integrins and tyrosine kinase receptors.

Microbiological assay for gatifloxacin in pharmaceutical formulations.

A simple, sensitive and specific agar diffusion bioassay for the antibacterial gatifloxacin was developed using a strain of Bacillus subtilis ATCC 9372 as the test organism. Gatifloxacin could be measured in tablets and raw material at concentration ranging 4-16 microgml(-1). The calibration graph for gatifloxacin was linear from 4.0 to 16.0 microgml(-1). A prospective validation of the method demonstrated that the method was linear (r2=0.9993), precise (R.S.D.=1.14%) and accurate. The results confirmed its precision and did not differ significantly from others methods described in the literature. The validated method yielded good results in terms of the range, linearity, precision, accuracy, specificity and recovery. We concluded that the microbiological assay is satisfactory for in vitro quantification of the antibacterial activity of gatifloxacin.

Determination of beta2-agonists in bovine urine: comparison of two extraction/clean-up procedures for high-resolution gas chromatography-mass spectrometry analysis.

Two extraction/clean-up analytical procedures were investigated and compared regarding their recovery and matrix-purification efficiency for screening beta2-agonist residues in fortified bovine urine by high-resolution gas chromatography-mass spectrometry (GC-MS). The first procedure, based on an analytical method originally developed for detecting anabolic steroids, consists of the employment of the nonionic resin, Amberlite XAD-2, a styrene-divinylbenzene copolymer for solid-phase extraction (SPE), followed by liquid-liquid extraction with diethyl ether. The second focuses on the use of a mixed SPE cartridge (reversed-phase and ion-exchange sorbent, Bond Elut Certify). In both cases, the trimethylsilylated derivatives were analyzed by GC-MS with an ion-trap detector. Clenbuterol, salbutamol, and terbutaline were used to spike urine samples during the comparison experimental phase. Afterwards, tulobuterol, mabuterol, mapenterol, cimbuterol, and brombuterol were included in the evaluation of the second procedure (the Bond Elut Certify procedure). At this stage, the detection was accomplished by GC-MS (quadrupole mass analyzer) with selective ion monitoring acquisition. The isotopic dilution method with the hexadeuterated analogues of clenbuterol and salbutamol was applied to prepare calibration curves and calculate recovery percentages. With XAD-2 resin, terbutaline and salbutamol (resorcinol and phenol-type beta2-agonists, respectively) could not be detected at 20 ng/mL or at 40 ng/mL. In spite of clenbuterol having been detected at 20 ng/mL, the results obtained were not reproducible. The use of the reversed-phase and ion-exchange sorbent Bond Elut Certify allowed multiresidue detection and showed several advantages for the screening of clenbuterol such as higher recoveries, cleaner final extracts, reduced sample preparation time, less labor intensive, and easier solvent consumption and disposal. Recoveries over 88% (concentrations ranging from 0.5 to 10 ppb) and limits of detection equal to 0.5 ppb were met for all the beta2-agonists studied with the last method.

Controlled introduction of selenium into Chlorella cells.

Selenium (Se) is an important element in the antioxidant system of the human body, and Chlorella, well-known for its therapeutic effects, is the ideal carrier to offer it in the wanted organic form. The kinetics of Se absorption by growing algal cells and its distribution in the cells are studied using radioactive 75Se labelled solutions. There is a rapid Se absorption within the first few minutes at the cell surfaces where it is irreversibly fixed and cannot be absorbed by the human body. In the final state, reached after 24-48 hr, about 40% of the total fixed Se is inside the cells in the wanted organic-bound form.