Changes in starch-bound lysophospholipids and lysophospholipase in germinating glacier and Hi amylose glacier barley varieties

Total starch, amylose content and amylose-included lipid phosphorus and lysophosphatidylcholine (LPC) were measured in normal Glacier (G) and Hi Amylose Glacier (HA) barley varieties during germination. From days three to six, alkaline and acidic lysophospholipase (LPL) activities in the starchy endosperm were measured and the distribution of these activities between a soluble and particulate form determined. During germination the amylose content of the starches increases as the total starch levels decline. The starch-bound LPC and lipid phosphorus disappear at the same rate between days three and six in both barley varieties, indicating no discrimination among the different lipid-included amylose population for degradation. However, both lipid phosphorus and LPC disappear more rapidly in the G than in the HA variety. This is presumably due to the slightly larger content of LPC per mg amylose of the G than of the HA variety, equivalent to 134 and 150 anhydroglucose residues per lipid molecule in G and HA, respectively. There is no increase in starch-bound lipid phosphorus or LPC expressed as nmol of phosphorus or LPC per mg amylose as amylose content declines, indicating no selective resistance of lipid-included amylose to degradation. The alkaline and acidic LPC activities in each variety increase 2–4-fold between days four and five. In both varieties ca 30% of the acidic LPL and ca 50–60% of the alkaline LPL is particulate from days three to six. No correlation can be made between the content of amylose or amylose-included lipid and particulate LPL activity. However, the possibility that particulate LPL activity is associated with specific populations of residual amylose-included lipid molecules cannot be excluded.     

Redox-active antioxidant modulation of lipid signaling in vascular endothelial cells: vitamin C induces activation of phospholipase D through phospholipase A2, lipoxygenase, and cyclooxygenase

We have earlier reported that the redox-active antioxidant, vitamin C (ascorbic acid), activates the lipid signaling enzyme, phospholipase D (PLD), at pharmacological doses (mM) in the bovine lung microvascular endothelial cells (BLMVECs). However, the activation of phospholipase A(2) (PLA(2)), another signaling phospholipase, and the modulation of PLD activation by PLA(2) in the ECs treated with vitamin C at pharmacological doses have not been reported to date. Therefore, this study aimed at the regulation of PLD activation by PLA(2) in the cultured BLMVECs exposed to vitamin C at pharmacological concentrations. The results revealed that vitamin C (3-10 mM) significantly activated PLA(2) starting at 30 min; however, the activation of PLD resulted only at 120 min of treatment of cells under identical conditions. Further studies were conducted utilizing specific pharmacological agents to understand the mechanism(s) of activation of PLA(2) and PLD in BLMVECs treated with vitamin C (5 mM) for 120 min. Antioxidants, calcium chelators, iron chelators, and PLA(2) inhibitors offered attenuation of the vitamin C-induced activation of both PLA(2) and PLD in the cells. Vitamin C was also observed to significantly induce the formation and release of the cyclooxygenase (COX)- and lipoxygenase (LOX)-catalyzed arachidonic acid (AA) metabolites and to activate the AA LOX in BLMVECs. The inhibitors of PLA(2), COX, and LOX were observed to effectively and significantly attenuate the vitamin C-induced PLD activation in BLMVECs. For the first time, the results of the present study revealed that the vitamin C-induced activation of PLD in vascular ECs was regulated by the upstream activation of PLA(2), COX, and LOX through the formation of AA metabolites involving oxidative stress, calcium, and iron.     

Structural coloration in a fossil feather

Investigation of feathers from the famous Middle Eocene Messel Oil Shale near Darmstadt, Germany shows that they are preserved as arrays of fossilized melanosomes, the surrounding beta-keratin having degraded. The majority of feathers are preserved as aligned rod-shaped eumelanosomes. In some, however, the barbules of the open pennaceous, distal portion of the feather vane are preserved as a continuous external layer of closely packed melanosomes enclosing loosely aligned melanosomes. This arrangement is similar to the single thin-film nanostructure that generates an iridescent, structurally coloured sheen on the surface of black feathers in many lineages of living birds. This is, to our knowledge, the first evidence of preservation of a colour-producing nanostructure in a fossil feather and confirms the potential for determining colour differences in ancient birds and other dinosaurs.     

The crystal structure of superoxide dismutase from Plasmodium falciparum

Background  

Superoxide dismutases (SODs) are important enzymes in defence against oxidative stress. In Plasmodium falciparum, they may be expected to have special significance since part of the parasite life cycle is spent in red blood cells where the formation of reactive oxygen species is likely to be promoted by the products of haemoglobin breakdown. Thus, inhibitors of P. falciparum SODs have potential as anti-malarial compounds. As a step towards their development we have determined the crystal structure of the parasite's cytosolic iron superoxide dismutase.     

Transcontinental Phylogeography of the Daphnia pulex Species Complex

Daphnia pulex is quickly becoming an attractive model species in the field of ecological genomics due to the recent release of its complete genome sequence, a wide variety of new genomic resources, and a rich history of ecological data. Sequences of the mitochondrial NADH dehydrogenase subunit 5 and cytochrome c oxidase subunit 1 genes were used to assess the global phylogeography of this species, and to further elucidate its phylogenetic relationship to other members of the Daphnia pulex species complex. Using both newly acquired and previously published data, we analyzed 398 individuals from collections spanning five continents. Eleven strongly supported lineages were found within the D. pulex complex, and one lineage in particular, panarctic D. pulex, has very little phylogeographical structure and a near worldwide distribution. Mismatch distribution, haplotype network, and population genetic analyses are compatible with a North American origin for this lineage and subsequent spatial expansion in the Late Pleistocene. In addition, our analyses suggest that dispersal between North and South America of this and other species in the D. pulex complex has occurred multiple times, and is predominantly from north to south. Our results provide additional support for the evolutionary relationships of the eleven main mitochondrial lineages of the D. pulex complex. We found that the well-studied panarctic D. pulex is present on every continent except Australia and Antarctica. Despite being geographically very widespread, there is a lack of strong regionalism in the mitochondrial genomes of panarctic D. pulex – a pattern that differs from that of most studied cladocerans. Moreover, our analyses suggest recent expansion of the panarctic D. pulex lineage, with some continents sharing haplotypes. The hypothesis that hybrid asexuality has contributed to the recent and unusual geographic success of the panarctic D. pulex lineage warrants further study.     

Polymorphic phase behavior of cardiolipin derivatives studied by 31P NMR and X-ray diffraction

The polymorphic phase behavior of cardiolipin (diphosphatidylglycerol) analogues with two to five chains per phospholipid head group, namely, dilysocardiolipin, monolysocardiolipin, cardiolipin, and acylcardiolipin, respectively, has been studied by 31P NMR and X-ray diffraction. Dilysocardiolipin dispersions at low salt concentration are micellar, and a transition to a lamellar phase takes place between 1 and 2 M NaCl. From light-scattering measurements, it is also found that a transition takes place from the micellar state with a midpoint at 5.2 mM CaCl2, 0.95 M HClO4, and 1.5 M NaCl. Monolysocardiolipin dispersions are lamellar throughout the concentration range from zero to saturated NaCl. Cardiolipin dispersions undergo a transition from a lamellar to an inverted hexagonal phase between 1 and 2 M NaCl. Acylcardiolipin dispersions are in an inverted hexagonal phase throughout the concentration range from zero to saturated NaCl. The chemical shift anisotropies of both phosphate groups in dilysocardiolipin and of one of the phosphate groups in monolysocardiolipin are drastically reduced in the lamellar phase, indicating a different conformation of the phosphatidyl head group from that normally found in diacyl phospholipid bilayers. The results provide strong support for the "shape" concept of lipid polymorphism when viewed in its most general form including configurational entropy, hydrophobic effects, etc. and indicate the importance of head-group interactions in determining the lipid phase behavior.     

Genetic mapping at 3-kilobase resolution reveals inositol 1,4,5-triphosphate receptor 3 as a risk factor for type 1 diabetes in Sweden

We mapped the genetic influences for type 1 diabetes (T1D), using 2,360 single-nucleotide polymorphism (SNP) markers in the 4.4-Mb human major histocompatibility complex (MHC) locus and the adjacent 493 kb centromeric to the MHC, initially in a survey of 363 Swedish T1D cases and controls. We confirmed prior studies showing association with T1D in the MHC, most significantly near HLA-DR/DQ. In the region centromeric to the MHC, we identified a peak of association within the inositol 1,4,5-triphosphate receptor 3 gene (ITPR3; formerly IP3R3). The most significant single SNP in this region was at the center of the ITPR3 peak of association (P=1.7 x 10(-4) for the survey study). For validation, we typed an additional 761 Swedish individuals. The P value for association computed from all 1,124 individuals was 1.30 x 10(-6) (recessive odds ratio 2.5; 95% confidence interval [CI] 1.7-3.9). The estimated population-attributable risk of 21.6% (95% CI 10.0%-31.0%) suggests that variation within ITPR3 reflects an important contribution to T1D in Sweden. Two-locus regression analysis supports an influence of ITPR3 variation on T1D that is distinct from that of any MHC class II gene.