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Jorge Santos

Publications and source records attributed to Jorge Santos.

4 recordsLinked to original sources
PubMed2005

Effects of arsenic species and concentrations on arsenic accumulation by different fern species in a hydroponic system.

Two hydroponic experiments were conducted to evaluate factors affecting plant arsenic (As) hyperaccumulation. In the first experiment; two As hyperaccumulators (Pteris vittata and P. cretica mayii) were exposed to 1 and 10 mg L(-1) arsenite (AsIII) and monomethyl arsenic acid (MMA) for 4 wk. Total As concentrations in plants (fronds and roots) and solution were determined In the second experiment P. vittata and Nephrolepis exaltata (a non-As hyperaccumulator) were exposed to 5 mgL(-1) arsenate (AsV) and 20 mgL(-1) AsIIIfor 1 and 15 d. Total As and AsIII concentrations in plants were determined Compared to P. cretica mayii, P. vittata was more efficient in arsenic accumulation (1075-1666 vs. 249-627mg kg(-1) As in the fronds) partially because it is more efficient in As translocation. As translocation factor (As concentration ratio in fronds to roots) was 3.0-5.6 for P. vittata compared to 0.1 to 4.8 for P. cretica. Compared to N. exaltata, P. vittata was significantly more efficient in arsenic accumulation (38-542 vs. 4.8-71 mg kg(-1) As in thefronds) as well asAs translocation (1.3-5.6 vs. 0.2-0.5). In addition, P. vittata was much more efficient in As reduction from AsV to AsIII (83-84 vs. 13-24% AsIII in the fronds). Little As reduction occurred after 1-d exposure to AsV in both species indicates that As reduction was not instantaneous even in an As hyperaccumulator. Our data were consistent with the hypothesis that both As translocation and As reduction are important for plant As hyperaccumulation.

Arsenates↗
PubMed2004

Synthesis of alkylgalactosides using whole cells of Bacillus pseudofirmus species as catalysts.

Whole cells of alkaliphilic Bacillus pseudofirmus AR-199, induced for beta-galactosidase activity, were used for the synthesis of 1-hexyl-beta-d-galactoside and 1-octyl-beta-d-galactoside, respectively, by transglycosylation reaction between lactose and the corresponding alcohol acceptor. The product yield was strongly influenced by the initial water content in the reaction mixture. Water content of 10% (v/v) was optimal providing 3.6-36 mM hexyl galactoside from 10 to 150 mM lactose, and no secondary product hydrolysis. Product yield could be enhanced by supplementing the reaction mixture with more cells or partly replacing the product with fresh substrate, but was decreased with time to the initial equilibrium level. Cell permeabilisation or disruption resulted in increased reaction rate and higher product yield but was followed by product hydrolysis. Octyl galactoside synthesis using whole cells was optimal at water content of 2% (v/v) with a yield of 26%. The cells were immobilised in cryogels of polyvinyl alcohol for use in continuous process, where hexyl galactoside was produced with a constant yield of 50% from 50mM lactose for at least a week.

Alcohols↗
PubMed2004

Short-term psychological impact of predictive testing for Machado-Joseph disease: depression and anxiety levels in individuals at risk from the Azores (Portugal).

OBJECTIVE: The short-term impact of the pre-symptomatic genetic test (PT) for Machado-Joseph disease (MJD) in the Azores (Portuguese Islands) was assessed in 46 individuals at risk who completed the PT Program. METHODS: Scores for depression and anxiety were used as indicators of the subjects' emotional status immediately before the PT and 1 year after disclosure of the results. RESULTS: Global levels of participation in the Azorean PT Program for MJD were high (20.7%), particularly in Flores Island (35.8%). For the total sample, mean scores of depression and anxiety before and after the PT presented without clinical significance. No differences were found for depression and anxiety scores before and after the PT. Furthermore, when grouped by test results (carriers/non-carriers), there were no differences between pre- and post-test levels. CONCLUSIONS: Results indicate that the test result did not cause a decrease in the psychological well-being of the individuals tested. The high number of participants performing the PT in the small and isolated community of Flores Island, where MJD represents a source of stigma, was interpreted as an indication that in this particular population the PT offers the individuals at risk the possibility of liberating from a stigma, and, hence, from exclusion.

Adult↗