Hemin-Induced Membrane Sulfhydryl Oxidation: Possible Involvement of Thiyl Radicils

Sublytic levels (μM) of hemin destabilized RBC membrane as indicated by ghost fragmentation pattern using a laser viscodiffractometer. Furthermore, electron microscopic study shows that 5μM of hemin induced echinocytic transformation whereas higher hemin concentration (40μM) induced spherocytic transformation. In addition, hemin oxidized sulfhydryl groups in a dose dependent fashion and Electron Spin Resonance study suggests that such oxidation may involve a thiyl radical. Moreover, sulfhydryl compounds enhanced hemin-induced lipid peroxidation. Desferroxamine could prevent hemin-induced sulfhydryl oxidation as well as hemin-induced decrease in membrane stability. In contrast, vitamin E could effectively prevent hemin-induced lipid peroxidation but could not prevent hemin-mediated membrane destabilization.     

Combining SFA and LCA

This article describes a method that combines substance flow analysis (SFA) and life-cycle assessment (LCA). It was used to provide a focus in the heated Swedish polyvinylchloride (PVC) debate. For Sweden's PVC chain, all emissions related to PVC were inventoried and translated into LCA-theme scores. The theme scores were compared with total theme scores for all Swedish processes and were benchmarked on the basis of PVC's contribution to Sweden's gross national product (GNP). Mass flows oftwo PVC additives, lead and organotin, were compared with the total use of these metals in Sweden. PVC's contribution to global warming, smog formation, and waste volume was equal to or less than the benchmark. After implementation of planned measures, emissions of the toxic substances dioxins, mercury, and lead will be below the benchmark. We recommend that the Swedish PVC debate concentrate on the uncertainties of the effects of phthalates, small process emissions of persistent chlorinated substances (PBTs), lead and organotin in landfilled PVC, and emissions from PVC in accidental fire     

Subsurface irradiance reflectance spectra of inland waters differing in morphometry and hydrology

A database has been established for relating subsurface irradiance reflectance, i.e. water ‘colour’, to the optical properties and water quality parameters of more than 120 Dutch inland water bodies. The concentrations of total chlorophyll-a (TChl-a = chlorophyll-a plus phaeopigment), total suspended matter and the Secchi-disc depth varied between 0.6 and 468 mg m^-3, 0.8 and 98 g m^-3, and 0.15 and 5.50 m, respectively. The water bodies represented very different water types based on morphometry and hydrology. The depth ranged from 0.4 to 40 m, and the surface area from 0.25 ha (fens in the moorland Peel) to 1200 km² (Lake IJsselmeer). The mean specific phytoplankton absorption coefficient at 676 nm was 0.013 ± 0.003 m² (mg TChl-a)^-1. The absorption by tripton and dissolved humic substances at 440 nm varied between 0.1 and 16.4 m^-1, and 0.1 and 65.5 m^-1, respectively. By using the spectral position and magnitude of the subsurface irradiance reflectance peak alone, it was possible to distinguish groups of water bodies according to a classical typology based on morphometry and hydrology. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis and thermodynamics of oligonucleotides containing chirally pure R(P) methylphosphonate linkages.

Methylphosphonate (MP) oligodeoxynucleotides (MPOs) are metabolically stable analogs of conventional DNA containing a methyl group in place of one of the non-bonding phosphoryl oxygens. All 16 possible chiral R(P) MP dinucleotides were synthesized and derivatized for automated oligonucleotide synthesis. These dimer synthons can be used to prepare (i) all-MP linked oligonucleotides having defined R(P) chirality at every other position (R(P) chirally enriched MPOs) or (ii) alternating R(P) MP/phosphodiester backbone oligonucleotides, depending on the composition of the 3'-coupling group. Chirally pure dimer synthons were also prepared with 2'-O-methyl sugar modifications. Oligonucleotides prepared with these R(P) chiral methylphosphonate linkage synthons bind RNA with significantly higher affinity than racemic MPOs.     

VARIATION AND LOCALIZATION OF FLAVONOID AGLYCONES IN HELIANTHUS ANNUUS (COMPOSITAE)

Flavonoid aglycone variation within Helianthus annuus, a species widely distributed throughout North America, was analyzed. Flavonoid aglycones of H. annuus consist of two types, flavones and chalcones. The flavone aglycones are sequestered in glandular trichomes that occur on both leaf surfaces, whereas the chalcone aglycones appear to be incorporated in the waxy leaf cuticle. Considerable variation in flavonoid profile was observed with some plants exhibiting as few as one, and others as many as seven of the eight aglycones detected. No definable phytogeographic patterns were observed for this flavonoid variation. Flavonoid aglycone variation also did not differentiate the infraspecific taxa within H. annuus.     

Mite pockets of lizards, a possible means of reducing damage by ectoparasites

Many scattered lizard groups have small skin invaginations in such places as the neck, axilla, groin and postfemoral region. These frequently contain feeding chiggers (the larvae of trombiculid mites) which, in general, are much commoner on species with pockets than on those without. Mite pockets appear to have evolved many times, being found in at least five families (Iguanidae, Chamaeleonidae, Gekkonidae, Lacertidae, Scincidae) and are most abundant in warm areas that are not extremely dry. They are present in newly hatched animals and embryos of viviparous forms and so cannot be produced in direct response to the mites. Typically, the epidermis of infested pockets is hyperplastic and resilient, rapidly repairing damage caused by feeding mites, and the dermis contains dense concentrations of lymphoid cells. It is suggested that mite pockets have evolved in forms prone to trombiculid infestation and ameliorate the damage that this causes by concentrating chiggers in places that are equipped to minimize the harm they do.     

Incubation effort in relation to male attractiveness in zebra finches Taeniopygia guttata

The division of labour in parental care between the two sexes varies between and within species. In birds, parents have been shown to invest more into egg production and nestling care when paired with an attractive rather than an unattractive mate, as predicted by the differential allocation hypothesis. Here we investigate variation in the female's and male's share of incubation behaviour, a vital, and costly, period of parental care during which the embryo is vulnerable to perturbations in developmental conditions. We manipulated the attractiveness of male zebra finches Taeniopygia guttata , using red or green leg-rings. To simulate their natural social environment we allowed them to breed in outdoor aviaries. All males within an aviary were given the same coloured ring to avoid ring-colour related assortative mating. Males within a colony, however, were still expected to show some variation in attractiveness with the earliest laying females possibly pairing with the most attractive males. Indeed we found that both factors played a role in explaining female incubation effort. Among females mated to red ringed males, earlier laying females contributed significantly more to incubation than late laying females, but no such pattern was found in females mated to green ringed males. Overall, there were no differences in the level of incubation provided by both parents between treatment groups, suggesting some compensation within the pair. Hatching success was correlated with a pair's total incubation effort. These results suggest that variation in the division of parental care between the sexes is in agreement with both increased effort of females mated with attractive males, and females compensating for the reduced effort of attractive males seeking further mating opportunities. These two factors can act at the same time in natural populations and both should be considered when explaining variation in division of labour between the sexes.     

The Matrix Protein of Nipah Virus Targets the E3-Ubiquitin Ligase TRIM6 to Inhibit the IKKε Kinase-Mediated Type-I IFN Antiviral Response

For efficient replication, viruses have developed mechanisms to evade innate immune responses, including the antiviral type-I interferon (IFN-I) system. Nipah virus (NiV), a highly pathogenic member of the Paramyxoviridae family (genus Henipavirus), is known to encode for four P gene-derived viral proteins (P/C/W/V) with IFN-I antagonist functions. Here we report that NiV matrix protein (NiV-M), which is important for virus assembly and budding, can also inhibit IFN-I responses. IFN-I production requires activation of multiple signaling components including the IκB kinase epsilon (IKKε). We previously showed that the E3-ubiquitin ligase TRIM6 catalyzes the synthesis of unanchored K48-linked polyubiquitin chains, which are not covalently attached to any protein, and activate IKKε for induction of IFN-I mediated antiviral responses. Using co-immunoprecipitation assays and confocal microscopy we show here that the NiV-M protein interacts with TRIM6 and promotes TRIM6 degradation. Consequently, NiV-M expression results in reduced levels of unanchored K48-linked polyubiquitin chains associated with IKKε leading to impaired IKKε oligomerization, IKKε autophosphorylation and reduced IFN-mediated responses. This IFN antagonist function of NiV-M requires a conserved lysine residue (K258) in the bipartite nuclear localization signal that is found in divergent henipaviruses. Consistent with this, the matrix proteins of Ghana, Hendra and Cedar viruses were also able to inhibit IFNβ induction. Live NiV infection, but not a recombinant NiV lacking the M protein, reduced the levels of endogenous TRIM6 protein expression. To our knowledge, matrix proteins of paramyxoviruses have never been reported to be involved in innate immune antagonism. We report here a novel mechanism of viral innate immune evasion by targeting TRIM6, IKKε and unanchored polyubiquitin chains. These findings expand the universe of viral IFN antagonism strategies and provide a new potential target for development of therapeutic interventions against NiV infections.     

Intraspecific Variation in the Amino Acid Content of Floral Nectar

In order to evaluate the constancy of amino acid composition and concentration, several randomly collected samples of genuine floral nectar from different flowers of several plant species were analysed. Although there seems to exist a rough pattern of species-specific nectar amino acid composition, amino acid concentration varied strongly from sample to sample. Apart from the lack of constancy in concentration of floral amino acids, our samples do not show amino acid concentration values as assigned typical for the pertinent pollination mode by other workers.     

Cyanobacterial glutamate 1-semialdehyde aminotransferase: requirement for pyridoxamine phosphate

Glutamate 1-semialdehyde aminotransferase has been separated from metabolically related activities by gel filtration and affinity chromatography. The enzyme was inhibited by gabaculin, 4-amino 5-fluoropentanoic acid and pyridoxal 5-phosphate and stimulated by pyridoxamine 5-phosphate. The activity of enzyme recovered by elution after electrophoresis in non-denaturing polyacrylamide gels was wholly dependent on pyridoxamine 5-phosphate. A mechanism for the enzyme-catalysed reaction based on these observations is discussed.Abbreviations AFPA 4-amino 5-fluoropentanoic acid - ALA -aminolaevulinic acid - DTT dithiothreitol - GSA glutamate 1-semialdehyde - PAL-P pyridoxal 5-phosphate - PAM-P pyridoxamine 5-phosphate - PCC Paris Culture Collection