The effect of ultrafine WO3 nanoparticles on the organization of thylakoids enriched in photosystem II and energy transfer in photosystem II complexes.

In this work, a new approach to construct self-assembled hybrid systems based on natural PSII-enriched thylakoid membranes (PSII BBY) is demonstrated. Superfine m-WO3 NPs (≈1-2 nm) are introduced into PSII BBY. Transmission electron microscopy (TEM) measurements showed that even the highest concentrations of NPs used did not degrade the PSII BBY membranes. Using atomic force microscopy (AFM), it is shown that the organization of PSII BBY depends strongly on the concentration of NPs applied. This proved that the superfine NPs can easily penetrate the thylakoid membrane and interact with its components. These changes are also related to the modified energy transfer between the external light-harvesting antennas and the PSII reaction center, shown by absorption and fluorescence experiments. The biohybrid system shows stability at pH 6.5, the native operating environment of PSII, so a high rate of O2 evolution is expected. In addition, the light-induced water-splitting process can be further stimulated by the direct interaction of superfine WO3 NPs with the donor and acceptor sides of PSII. The water-splitting activity and stability of this colloidal system are under investigation. RESEARCH HIGHLIGHTS: The phenomenon of the self-organization of a biohybrid system composed of thylakoid membranes enriched in photosystem II and superfine WO3 nanoparticles is studied using AFM and TEM. A strong dependence of the organization of PSII complexes within PSII BBY membranes on the concentration of NPs applied is observed. This observation turns out to be crucial to understand the complexity of the mechanism of the action of WO3 NPs on modifications of energy transfer from external antenna complexes to the PSII reaction center.

Prevalence of HLA-B*57:01 allele in Argentinean HIV-1 infected patients.

Hypersensitivity reaction to abacavir (ABC hypersensitivity syndrome, AHS) is strongly associated with the presence of the HLA-B*57:01 allele. This study was designed to estimate the prevalence of HLA-B*57:01 allele in Argentinean HIV-1 infected patients. We analyzed the presence of HLA-B*57:01 allele in 1646 HIV-1 infected patients from different regions of Argentina. This allele was detected in 81 patients; most of them corresponded to patients living in the central region of the country. The prevalence of HLA-B*57:01 was 4.9%, similar to other Caucasian populations and higher than other data reported for South American populations. This strongly supports screening for the presence of HLA-B*57:01 in abacavir treatment of HIV-1 in our country.

Evaluation of serologic markers for transfusion transmitted infectious diseases for allogeneic blood donors in Puerto Rico.

The purpose of this project is to assess the prevalence of serologic markers for transfusion transmitted infectious disease in allogeneic blood donors of the American Red Cross Blood Services (ARCBS) in Puerto Rico. Four hundred records were randomly selected from a population of 7718 first time volunteer donors from the ARCBS in P.R. covering the period from Jan. 1st to Jun. 30th, 1991. Variables obtained were: age, sex, presence of hepatitis B surface antigen (HBsAg), hepatitis B anti-core antibody (anti-HBc), hepatitis C virus antibody (anti-HCV), HIV 1/2 antibody, HTLV I/II antibody, RPR reactivity and ALT. The prevalence of serologic markers in our study is consistently higher than that found in similar studies in the U.S. population, except for HBsAg and HCV. This could be explained with the use of data from only first time volunteer donors since the prevalence is higher in this group than in repeat donors. None of the donors in this sample were positive for HBsAg probably due to the small sample. The prevalence of anti-HCV in this study is within the values found for the U.S. population.