Gene expression and molecular composition of phospholipids in rat brain in relation to dietary n-6 to n-3 fatty acid ratio

Rats were fed from conception till adulthood either with normal rat chow with a linoleic (LA) to linolenic acid (LNA) ratio of 8.2:1 or a rat chow supplemented with a mixture of perilla and soy bean oil giving a ratio of LA to LNA of 4.7:1. Fat content of the feed was 5%. Fatty acid and molecular species composition of ethanolamine phosphoglyceride was determined. Effect of this diet on gene expression was also studied. There was an accumulation of docosahexaenoic (DHA) and arachidonic acids (AA) in brains of the experimental animals. Changes in the ratio sn-1 saturated, sn-2 docosahexaenoic to sn-1 monounsaturated, sn-2 docosahexaenoic were observed. Twenty genes were found overexpressed in response to the 4.7:1 mixture diet and four were found down-regulated compared to normal rat chow. Among them were the genes related to energy household, lipid metabolism and respiration. The degree of up-regulation exceeded that observed with perilla with a ratio of LA to LNA 8.2:1 [Proc. Natl. Acad. Sci. U. S. A. 99 (2002) 2619]. It was concluded that brain sensitively reacts to the fatty acid composition of the diet. It was suggested that alteration in membrane architecture and function coupled with alterations in gene expression profiles may contribute to the observed beneficial impact of n-3 type polyunsaturated fatty acids on cognitive functions.     

Subcellular localization and N-glycosylation of human ABCC6, expressed in MDCKII cells

Mutations in the gene coding for a human ABC transporter protein, ABCC6 (MRP6), are responsible for the development of pseudoxanthoma elasticum. Here, we demonstrate that human ABCC6, when expressed by retroviral transduction in polarized mammalian (MDCKII) cells, is exclusively localized to the basolateral membrane. The human ABCC6 in MDCKII cells was found to be glycosylated, in contrast to the underglycosylated form of the protein, as expressed in Sf9 cells. In order to localize the major glycosylation site(s) in ABCC6, we applied limited proteolysis on the fully glycosylated and underglycosylated forms, followed by immunodetection with region-specific antibodies for ABCC6. Our results indicate that Asn15, which is located in the extracellular N-terminal region of human ABCC6, is the only N-glycosylation site in this protein. The polarized mammalian expression system characterized here provides a useful tool for further examination of routing, glycosylation, and function of the normal and pathological variants of human ABCC6.     

Proton transport by proteorhodopsin requires that the retinal Schiff base counterion Asp-97 be anionic

At pH >7, proteorhodopsin functions as an outward-directed proton pump in cell membranes, and Asp-97 and Glu-108, the homologues of the Asp-85 and Asp-96 in bacteriorhodopsin, are the proton acceptor and donor to the retinal Schiff base, respectively. It was reported, however [Friedrich, T. et al. (2002) J. Mol. Biol., 321, 821-838], that proteorhodopsin transports protons also at pH <7 where Asp-97 is protonated and in the direction reverse from that at higher pH. To explore the roles of Asp-97 and Glu-108 in the proposed pumping with variable vectoriality, we compared the photocycles of D97N and E108Q mutants, and the effects of azide on the photocycle of the E108Q mutant, at low and high pH. Unlike at high pH, at a pH low enough to protonate Asp-97 neither the mutations nor the effects of azide revealed evidence for the participation of the acidic residues in proton transfer, and as in the photocycle of the wild-type protein, no intermediate with unprotonated Schiff base accumulated. In view of these findings, and the doubts raised by absence of charge transfer after flash excitation at low pH, we revisited the question whether transport occurs at all under these conditions. In both oriented membrane fragments and liposomes reconstituted with proteorhodopsin, we found transport at high pH but not at low pH. Instead, proton transport activity followed the titration curve for Asp-97, with an apparent pK(a) of 7.1, and became zero at the pH where Asp-97 is fully protonated.     

The evolution of immune defense and song complexity in birds

Abstract There are three main hypotheses that explain how the evolution of parasite virulence could be linked to the evolution of secondary sexual traits, such as bird song. First, as Hamilton and Zuk proposed a role for parasites in sexual selection, female preference for healthy males in heavily parasitized species may result in extravagant trait expression. Second, a reverse causal mechanism may act, if sexual selection affects the coevolutionary dynamics of host-parasite interactions per se by selecting for increased virulence. Third, the immuno-suppressive effects of ornamentation by testosterone or limited resources may lead to increased susceptibility to parasites in species with elaborate songs. Assuming a coevolutionary relationship between parasite virulence and host investment in immune defense we used measures of immune function and song complexity to test these hypotheses in a comparative study of passerine birds. Under the first two hypotheses we predicted avian song complexity to be positively related to immune defense among species, whereas this relationship was expected to be negative if immuno-suppression was at work. We found that adult T-cell mediated immune response and the relative size of the bursa of Fabricius were independently positively correlated with a measure of song complexity, even when potentially confounding variables were held constant. Nestling T-cell response was not related to song complexity, probably reflecting age-dependent selective pressures on host immune defense. Our results are consistent with the hypotheses that predict a positive relationship between song complexity and immune function, thus indicating a role for parasites in sexual selection. Different components of the immune system may have been independently involved in this process.     

Effect of classic preconditioning on the gene expression pattern of rat hearts: a DNA microarray study

With the aim to enhance the plant vitamin E content, the barley gene encoding 4-hydroxyphenylpyruvate dioxygenase was overexpressed in tobacco plants under control of the 35S promoter. Transgenic lines have a higher capacity for homogentisate biosynthesis as evident by a more than 10-fold higher resistance towards the bleaching herbicide sulcotrione. Seeds from transgenic lines have an up to two-fold enhanced level of vitamin E without a change in the ratio of γ-tocopherol and γ-tocotrienol. While the vitamin E content is not affected in leaves, the level of plastoquinone is enhanced in leaves of transgenic lines during leaf senescence.     

Synthetic and structural studies on Pyrularia pubera thionin: a single-residue mutation enhances activity against Gram-negative bacteria

The thionin from Pyrularia pubera (Pp-TH), a 47-residue peptide with four internal disulfide bonds, was efficiently produced by chemical synthesis. Its antimicrobial activity in vitro against several representative pathogens (EC(50)=0.3-3.0 microM) was identical to that of natural Pp-TH. This peptide has a unique Asp(32) instead of the consensus Arg found in other thionins of the same family. In order to evaluate the effect of this mutation, the Arg(32) analogue (Pp-TH(D32R)) was also synthesized and showed a significant increase in antibiotic activity against several Gram-negative bacteria, whereas it retained the same activity against other pathogens. The overall structure of Pp-TH(D32R) was maintained, though a slight decrease in the helical content of the peptide was observed.     

Endocrine characteristics of polycystic ovary syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is probably the most prevalent endocrinopathy in women and the most common cause of anovulatory infertility. Patients with PCOS have clinical and biochemical features consistent with the ultrasound diagnosis and they are likely to face the problems of hyperandrogenism, subfertility and recurrent miscarriage. The aim of the present review is to summarize our present knowledge on the hormonal background of this very prevalent syndrome and to give some clinical examples how the present knowledge can be applied to treat PCOS patients according to their current problem, such as menstrual cycle disorder, hirsutism, infertility or to prevent late consequences as diabetes mellitus. The etiology and pathogenesis of PCOS is still a matter of controversies, but it is apparent that inappropriate gonadotropin secretion, obesity, hyperinsulinism and insulin resistance are the major determining factors in the development of ovarian hyperandrogenism an chronic anovulation. Reversal of insulin resistance in PCOS constitutes the fundamental goal in the management of hyperandrogenic anovulatory infertility and in the prevention of long-term consequences. The value of the insulin sensitizer metformin therapy awaits further evaluation and it should be integrated in the spectrum of therapeutical options that include the discussed surgical methods and GnRH analogues as well.     

Differential mercury volatilization by tobacco organs expressing a modified bacterial merA gene

INTRODUCTIONEnvironmental pollution is an increasing prob-lem both fOr developing and developed countries.Mercury, both in organic and ionic fOrm, is one of themost hazardous pollutants among the heavy met-als[l]and its accumuIation in human body results ininactivation of metabolic enzymes and structuralproteins[2, 3] giving rise to serious health problems(Minamatasyndrome).Usually mercury pollution is caused by indus-trial and agricultural activities, releasing mercuryinto air, water an…     

Beta-galactosidase of Penicillium chrysogenum: production, purification, and characterization of the enzyme

Intracellular beta-galactosidase from Penicillium chrysogenum NCAIM 00237 was purified by procedures including precipitation with ammonium sulfate, ion-exchange chromatography on DEAE-Sephadex, affinity chromatography, and chromatofocusing. These steps resulted a purification of 66-fold, a yield of about 8%, and a specific activity of 5.84 U mg(-1) protein. Some enzyme characteristics were determined using o-nitrophenyl-beta-d-galactopyranoside as substrate. The pH and temperature optimum of the activity were about 4.0 and 30 degrees C respectively. The K(m) and pI values were 1.81 mM and 4.6. beta-Galactosidase of P. chrysogenum is a multimeric enzyme of about 270 kDa composed of monomers with a molecular mass of 66 kDa.