Production of L-asparaginase of pharmaceutical nterest from yeasts isolated from the Antarctic continent / Produção de L-asparaginase de interesse farmacêutico a partir de leveduras isoladas do continente Antártico

The L-asparaginase (ASNase) obtained from yeasts species has been poorly studied and a new yeast ASNase could be an alternative to minimize the side effect in the treatment of lymphoblastic leukemia. The Antarctic ecosystems have a great potential to obtain novel enzymes produced from psychrophilic and psychrotolerant microorganisms. Yeasts isolated from samples collected in the Antarctic Peninsula by the PROANTAR expedition team were tested for the production of ASNase and L-glutaminase (GLNase). From this screening, the strain Leucosporidium scottii L115 presented the highest ASNase activity (6.24 U g-1 of dried cell weight (dcw)) with a combination of low GLNase activity (0.41 U g-1 dcw). The ASNase belonging to L. scottii L115 (LsASNase) was purified 227 fold with a specific activity of 137.01 U mg-1 at 37 ºC, and with 0.93 U mg-1 for GLNase. Moreover, the maximum activity was observed at pH 7.5 at 55 ºC. The enzyme is a multimer presenting a single band of 54.5 kDa of molecular weight in reduced conditions and 462 kDa by size exclusion chromatography. The LsASNase is a glycosylated enzyme that presented a band lower at 25 kDa when was treated with PGNase F. The enzymatic kinetic reveals an allosteric regulation of the enzyme and the kinetic parameters were determined at 37º C, pH 7.0 as K0.5 = 233 µM, kcat = 54.7 s-1 and nH = 1.52 demonstrating a positive cooperativity by the enzyme and the substrate. The ASNase production by L. scottii L115 was improved by applying DoE for the culture medium development. The PB and CDD designs were used to optimize the ASNase production providing the nutrient values of 6.15 g L-1 of proline, 28.34 g L-1 sucrose, and 15.61 g L-1 of glycerol for a maximal production. The synthetic medium containing the optimized quantities was added with the salts: KCl, 0.52 g L-1; MgSO4.7H2O, 0.52 g L-1; CuNO3.3H2O, 0.001 g L-1; ZnSO4.7H2O, 0.001 g L-1; FeSO4.7H2O, 0.001 g L-1.The optimized medium produces a 23.75 ULh-1 of ASNase in shake flask culture. Furthermore, L. scottii is characterized as an oleaginous yeast that accumulates lipids with a suitable fatty acid profile. The production of ASNase and lipids were scaled up in the 1 L bioreactor to evaluate the initial cell concentration, carbon source, and oxygen transfer rate (kLa).The experiments were performed at 15ºC in the bioreactor BIOSTAT®Q plus (Sartorius Stedim, Germany) in batch mode, using 0.5 L of the optimized medium culture in phosphate buffer 50 mM pH 7.0. The initial cell concentration was evaluated at 1%, 3%, and 5% (v/v). Sucrose and glycerol were tested alone to examine if the combination of both is mandatory to produce ASNase. All these assays were carried in duplicate. The kLa was assessed through a CCD design in the range of 1.42 - 123.0 h-1. The performance in bioreactor showed the productivity of 36.95 ULh-1of ASNase under the optimized conditions (growth temperature 15º C, X0: 5 g L-1, pH 7.0, 48 h, kLa 89-92 h-1). The cultivation of L. scottii L115 at 15ºC in sucrose and glycerol as carbon sources generate an interesting lipid profile, where it presents monounsaturated and polyunsaturated lipids

A L-asparaginase (ASNase) obtida a partir de espécies de leveduras tem sido pouco estudada e uma nova ASNase de levedura pode ser uma alternativa para minimizar os efeitos adversos no tratamento da leucemia linfoblástica. Os ecossistemas Antárticos têm um grande potencial para obter novas enzimas produzidas a partir de microorganismos psicrofílicos e psicotrolerantes. As leveduras isoladas de amostras coletadas na Península Antártica pela equipe de expedição do PROANTAR foram testadas para a produção de ASNase e L-glutaminase (GLNase). A partir desta triagem, a cepa Leucosporidium scottii L115 apresentou a maior atividade de ASNase (6,24 U g-1 dcw) com uma combinação de baixa atividade de GLNase (0,41 U g-1 dcw). A ASNase pertencente a L. scottii L115 (LsASNase) foi purificada 227 vezes com uma atividade específica de 137,01 U mg-1 a 37 ºC e com 0,93 U mg-1 de GLNase. A atividade máxima foi observada a pH 7,5 a 55 ºC. A enzima é um multímero que apresenta uma banda única de 54,5 kDa de peso molecular em condições redutoras e 462 kDa por cromatografia de exclusão molecular. A LsASNase é uma enzima glicosilada que apresentou uma banda menor a 25 kDa quando tratada com PGNase F. A cinética enzimática revela uma regulação alostérica da enzima e os parâmetros cinéticos foram determinados a 37º C, pH 7,0 como K0,5 = 233 µM, kcat = 54,7 s-1 e nH = 1,52 demonstrando uma cooperatividade positiva pela enzima e o substrato. A produção de ASNase por L. scottii L115 foi melhorada aplicando DoE para o desenvolvimento do meio de cultura. Os desenhos experimentais de PB e CDD forma usados para otimizar a produção de ASNase e forneceram os valores de nutrientes de 6,15 gL-1 de prolina, 28,34 gL-1 de sacarose e 15,61 gL-1 de glicerol para uma produção máxima. O meio sintético contendo as quantidades otimizadas foi adicionado com os sais: : KCl, 0.52 g L-1; MgSO4.7H2O, 0.52 g L-1; CuNO3.3H2O, 0.001 g L-1; ZnSO4.7H2O, 0.001 g L-1; FeSO4.7H2O, 0.001 g L-1.O meio otimizado produz 23.75 ULh-1 de ASNase em cultivo em frasco agitado. Além disso, L. scottii é caracterizada como uma levedura oleaginosa que acumula lipídios com um perfil adequado de ácidos graxos. A produção de ASNase e lipídios foi ampliada no biorreator de 1 L para avaliar a concentração celular inicial, fonte de carbono e taxa de transferência de oxigênio (kLa). Os experimentos foram realizados a 15ºC no biorreator BIOSTAT®Q plus (Sartorius Stedim) em modo batelada, utilizando 0,5 L da cultura de meio otimizado em tampão fosfato 50 mM pH 7,0. A concentração celular inicial foi avaliada em 1%, 3% e 5% (v / v). Sacarose e glicerol foram testados isoladamente para examinar se a combinação de ambos é obrigatória para produzir ASNase. Todos esses ensaios foram realizados em duplicado. O kLa foi avaliado através de um planejamento CCD na faixa de 1,42-123,0 h-1. O desempenho no biorreator mostrou a produtividade de 36,95 ULh-1 de ASNase sob condições otimizadas (temperatura de crescimento 15º C, X0: 5 g L-1, pH 7,0, 48 h, kLa 89-92 h-1). O cultivo de L. scottii L115 a 15ºC em sacarose e glicerol como fontes de carbono gera um perfil lipídico interessante, onde apresenta lipídios monoinsaturados e poliinsaturados

Wintering in Antarctica: impact on immune response of Indian expeditioners.

The immune system is one of the major thrust areas in understanding the effects of adverse climatic conditions on human health. Exposure to the Antarctic environment, such as isolation, cold, UV radiations, magnetic field, blizzards, circadian biorhythms, and fear of the unknown, modify various components of the immune system. Members of Antarctic expeditions suffer significant emotional strain as a result of physical isolation and social deprivation. The present study was performed on winter team members of the 28th Indian Scientific Expedition. In this study, different immunological parameters, which mainly include cytokines (TNF-α, IFN-γ, TGF-ß, and IL-4), chemokine MIP-1α, immunoglobulins (IgA, IgM and IgG), cortisol and netrin-1, were assayed in sera by ELISA. Results showed that TNF-α and MIP-1α levels were significantly increased in March, May and August while IFN-γ levels were increased in March and May while TGF-ß levels showed a significant decrease in March and May. Serum IgA levels were significantly increased during the entire period of the stressful expedition. Therefore, the present study suggests that serum IgA could be a potential biomarker for extreme environmental conditions.

Rights to food with a human face in the global south.

This article seeks to dispel the popular myth surrounding the food crises which precipitated food riots in the global South in 2008. Arguing from a structural and historical perspective, the article suggests that global hunger is a deep-rooted crisis that is embedded in the social and structural variables associated within the nation-state that places a restraint on the self-regulating capacity of nation-states in the South. Internationalizing the food crisis, however, will do more harm to the south's agricultural transformation and rural development. The article argues for integrated rural development that will increase output growth through an institutional, technological, and marketing strategy.