Iron-binding antioxidant capacity is impaired in diabetes mellitus

Increased lipid peroxidation contributes to diabetic complications and redox-active iron is known to play an important role in catalyzing peroxidation reactions. We aimed to investigate if diabetes affects the capacity of plasma to protect against iron-driven lipid peroxidation and to identify underlying factors. Glycemic control, serum iron, proteins involved in iron homeostasis, plasma iron-binding antioxidant capacity in a liposomal model, and non-transferrin-bound iron were measured in 40 type 1 and 67 type 2 diabetic patients compared to 100 nondiabetic healthy control subjects. Iron-binding antioxidant capacity was significantly lower in the plasma of diabetic subjects (83 +/- 6 and 84 +/- 5% in type 1 and type 2 diabetes versus 88 +/- 6% in control subjects, p < 0.0005). The contribution of transferrin, ceruloplasmin, and albumin concentrations to the iron-binding antioxidant capacity was lost in diabetes (explaining only 4.2 and 6.3% of the variance in type 1 and type 2 diabetes versus 13.9% in control subjects). This observation could not be explained by differences in Tf glycation, lipid, or inflammatory status and was not associated with higher non-transferrin-bound iron levels. Iron-binding antioxidant capacity is decreased in diabetes mellitus.     

Personality and congenital adrenal hyperplasia: Possible effects of prenatal androgen exposure

Influences of early androgen exposure on personality were investigated. Participants were either exposed to abnormal levels of androgens prenatally due to congenital adrenal hyperplasia (CAH, 40 females, 29 males), or were unaffected relative controls (29 females, 30 males). Compared to female controls, females with CAH were less tender-minded (p < .001; 16 Personality Factor Inventory (16PF)), and reported greater physical aggression (p = .03; Reinisch Aggression Inventory) and less interest in infants (p < .001; Melson's Questionnaire), but did not differ in dominance (16PF). Males with CAH did not differ from male controls in interest in infants but were less dominant (p = .008), and more tender-minded (p = .033) and reported reduced physical aggression (p = .025). Thus, both males and females with CAH showed alteration in three of the four constructs assessed. Prenatal androgen exposure may shift some, but not all, personality characteristics in the male-typical direction in females. It may also be associated with a decrease in some aspects of male-typical personality development in males, although personality differences in males with CAH could relate to illness.     

Transmitting tissue architecture in basal-relictual angiosperms: Implications for transmitting tissue origins

Carpel transmitting tissue is a major floral innovation that is essential for angiosperm success. It facilitates the rapid adhesion, hydration, and growth of the male gametophyte to the female gametophyte. As well, it functions as a molecular screen to promote male gametophytic competition and species-specific recognition and compatibility. Here, we characterize the transmitting tissue extracellular matrix (ECM) and pollen tube growth in basal-relictual angiosperms and test the hypothesis that a freely flowing ECM (wet stigma) was ancestral to a cuticle-bound ECM (dry stigma). We demonstrate that the most recent common ancestor of extant angiosperms produced an ECM that was structurally and functionally equivalent to a dry stigma. Dry stigmas are composed of a cuticle and primary wall that contains compounds that facilitate the adhesion and growth of the male gametophyte. These compounds include methyl-esterified homogalacturonans, arabinogalactan-proteins, and lipids. We propose that transmitting tissue evolved in concert with an increase in cuticle permeability that resulted from modifications in the biosynthesis and secretion of fatty acids needed for cuticle construction. Increased cuticle permeability exposed the male gametophyte to pre-existing molecules that enabled rapid male gametophyte adhesion, hydration, and growth as well as species-specific recognition and compatibility.     

Seasonal Genetic Influence on Serum 25-Hydroxyvitamin D Levels: A Twin Study

Background

Although environmental factors, mainly nutrition and UV-B radiation, have been considered major determinants of vitamin D status, they have only explained a modest proportion of the variation in serum 25-hydroxyvitamin D. We aimed to study the seasonal impact of genetic factors on serum 25-hydroxyvitamin D concentrations.

Methodology/Principal findings

204 same-sex twins, aged 39–85 years and living at northern latitude 60°, were recruited from the Swedish Twin Registry. Serum 25-hydroxyvitamin D was analysed by high-pressure liquid chromatography and mass spectrometry. Genetic modelling techniques estimated the relative contributions of genetic, shared and individual-specific environmental factors to the variation in serum vitamin D. The average serum 25-hydroxyvitamin D concentration was 84.8 nmol/l (95% CI 81.0–88.6) but the seasonal variation was substantial, with 24.2 nmol/l (95% CI 16.3–32.2) lower values during the winter as compared to the summer season. Half of the variability in 25-hydroxyvitamin D during the summer season was attributed to genetic factors. In contrast, the winter season variation was largely attributable to shared environmental influences (72%; 95% CI 48–86%), i.e., solar altitude. Individual-specific environmental influences were found to explain one fourth of the variation in serum 25-hydroxyvitamin D independent of season.

Conclusions/Significance

There exists a moderate genetic impact on serum vitamin D status during the summer season, probably through the skin synthesis of vitamin D. Further studies are warranted to identify the genes impacting on vitamin D status.     

Effects of Mutations Within Surface-Exposed Loops in the Pore-Forming Domain of the Cry9Ca Insecticidal Toxin of Bacillus thuringiensis

The pore-forming domain of Bacillus thuringiensis insecticidal Cry toxins is formed of seven amphipathic α-helices. Because pore formation is thought to involve conformational changes within this domain, the possible role of its interhelical loops in this crucial step was investigated with Cry9Ca double mutants, which all share the previously characterized R164A mutation, using a combination of homology modeling, bioassays and electrophysiological measurements. The mutations either introduced, neutralized or reversed an electrical charge carried by a single residue of one of the domain I loops. The ability of the 28 Cry9Ca double mutants to depolarize the apical membrane of freshly isolated Manduca sexta larval midguts was tested in the presence of either midgut juice or a cocktail of protease inhibitors because these conditions had been shown earlier to greatly enhance pore formation by Cry9Ca and its R164A single-site mutant. Most mutants retained toxicity toward neonate larvae and a pore-forming ability in the electrophysiological assay, which were comparable to those of their parental toxin. In contrast, mutants F130D, L186D and V189D were very poorly toxic and practically inactive in vitro. On the other hand, mutant E129A depolarized the midgut membrane efficiently despite a considerably reduced toxicity, and mutant Q192E displayed a reduced depolarizing ability while conserving a near wild-type toxicity. These results suggest that the conditions found in the insect midgut, including high ionic strength, contribute to minimizing the influence of surface charges on the ability of Cry9Ca and probably other B. thuringiensis toxins to form pores within their target membrane.     

No Differences in Soil Carbon Stocks Across the Tree Line in the Peruvian Andes

Reliable soil organic carbon (SOC) stock measurements of all major ecosystems are essential for predicting the influence of global warming on global soil carbon pools, but hardly any detailed soil survey data are available for tropical montane cloud forests (TMCF) and adjacent high elevation grasslands above (puna). TMCF are among the most threatened of ecosystems under current predicted global warming scenarios. We conducted an intensive soil sampling campaign extending 40 km along the tree line in the Peruvian Andes between 2994 and 3860 m asl to quantify SOC stocks of TMCF, puna grassland, and shrubland sites in the transition zone between the two habitats. SOC stocks from the soil surface down to the bedrock averaged (±standard error SE) 11.8 (±1.5, N = 24) kg C/m² in TMCF, 14.7 (±1.4, N = 9) kg C/m² in the shrublands and 11.9 (±0.8, N = 35) kg C/m² in the grasslands and were not significantly different (P > 0.05 for all comparisons). However, soil profile analysis revealed distinct differences, with TMCF profiles showing a uniform SOC distribution with depth, shrublands a linear decrease, and puna sites an exponential decrease in SOC densities with soil depth. Organic soil layer thickness reached a maximum (~70 cm) at the upper limit of the TMCF and declined with increasing altitude toward puna sites. Within TMCF, no significant increase in SOC stocks with increasing altitude was observed, probably because of the large variations among SOC stocks at different sites, which in turn were correlated with spatial variation in soil depth.     

Analysis of beta-carotene absorbance for studying structural properties of human plasma low-density lipoproteins

A novel spectrophotometric assay for monitoring structural rearrangements of native low-density lipoproteins (LDL) is proposed. The approach is based on the analysis of the visible light absorbance maximum of lipoproteins at approximately 461 nm assigned to beta-carotene situated in the hydrophobic parts of LDL. It offers a direct method to study the surface-interior coupling of the lipoprotein particle under physiological conditions. The detected signal is intrinsic to LDL and responsible for the most of the beta-carotene signal from the whole plasma. The negligible interference of beta-carotene absorbance due to the high-density lipoproteins is experimentally verified. Since beta-carotene absorbance belongs to the visible spectral region, no spectral overlapping/artifacts in plasma are expected. The signal sensitivity has been studied through conformational changes of LDL induced by ionic strength, by temperature, and by ligand binding. The results of caffeine binding to LDL indicate that there could be only one dominant type of binding site for caffeine on LDL particles. It can be concluded that visible spectrum characteristics of beta-carotene molecules offer advantages in LDL ligand binding studies which can possibly be extended to monitor the interactions of LDL directly in plasma.     

X4 modules represent a new family of carbohydrate-binding modules that display novel properties

The hydrolysis of the plant cell wall by microbial glycoside hydrolases and esterases is the primary mechanism by which stored organic carbon is utilized in the biosphere, and thus these enzymes are of considerable biological and industrial importance. Plant cell wall-degrading enzymes in general display a modular architecture comprising catalytic and non-catalytic modules. The X4 modules in glycoside hydrolases represent a large family of non-catalytic modules whose function is unknown. Here we show that the X4 modules from a Cellvibrio japonicus mannanase (Man5C) and arabinofuranosidase (Abf62A) bind to polysaccharides, and thus these proteins comprise a new family of carbohydrate-binding modules (CBMs), designated CBM35. The Man5C-CBM35 binds to galactomannan, insoluble amorphous mannan, glucomannan, and manno-oligosaccharides but does not interact with crystalline mannan, cellulose, cello-oligosaccharides, or other polysaccharides derived from the plant cell wall. Man5C-CBM35 also potentiates mannanase activity against insoluble amorphous mannan. Abf62A-CBM35 interacts with unsubstituted oat-spelt xylan but not substituted forms of the hemicellulose or xylo-oligosaccharides, and requires calcium for binding. This is in sharp contrast to other xylan-binding CBMs, which interact in a calcium-independent manner with both xylo-oligosaccharides and decorated xylans.     

The phylogenetic distribution of sphingomyelinase D activity in venoms of Haplogyne spiders

The venoms of Loxosceles spiders cause severe dermonecrotic lesions in human tissues. The venom component sphingomyelinase D (SMD) is a contributor to lesion formation and is unknown elsewhere in the animal kingdom. This study reports comparative analyses of SMD activity and venom composition of select Loxosceles species and representatives of closely related Haplogyne genera. The goal was to identify the phylogenetic group of spiders with SMD and infer the timing of evolutionary origin of this toxin. We also preliminarily characterized variation in molecular masses of venom components in the size range of SMD. SMD activity was detected in all (10) Loxosceles species sampled and two species representing their sister taxon, Sicarius, but not in any other venoms or tissues surveyed. Mass spectrometry analyses indicated that all Loxosceles and Sicarius species surveyed had multiple (at least four to six) molecules in the size range corresponding to known SMD proteins (31-35 kDa), whereas other Haplogynes analyzed had no molecules in this mass range in their venom. This suggests SMD originated in the ancestors of the Loxosceles/Sicarius lineage. These groups of proteins varied in molecular mass across species with North American Loxosceles having 31-32 kDa, African Loxosceles having 32-33.5 kDa and Sicarius having 32-33 kDa molecules.