Crosslinked elastic fibers are necessary for low energy loss in the ascending aorta

In the large arteries, it is believed that elastin provides the resistance to stretch at low pressure, while collagen provides the resistance to stretch at high pressure. It is also thought that elastin is responsible for the low energy loss observed with cyclic loading. These tenets are supported through experiments that alter component amounts through protease digestion, vessel remodeling, normal growth, or in different artery types. Genetic engineering provides the opportunity to revisit these tenets through the loss of expression of specific wall components. We used newborn mice lacking elastin (Eln^−/−) or two key proteins (lysyl oxidase, Lox^−/−, or fibulin-4, Fbln4^−/−) that are necessary for the assembly of mechanically-functional elastic fibers to investigate the contributions of elastic fibers to large artery mechanics. We determined component content and organization and quantified the nonlinear and viscoelastic mechanical behavior of Eln^−/−, Lox^−/−, and Fbln4^−/− ascending aorta and their respective controls. We confirmed that the lack of elastin, fibulin-4, or lysyl oxidase leads to absent or highly fragmented elastic fibers in the aortic wall and a 56–97% decrease in crosslinked elastin amounts. We found that the resistance to stretch at low pressure is decreased only in Eln^−/− aorta, confirming the role of elastin in the nonlinear mechanical behavior of the aortic wall. Dissipated energy with cyclic loading and unloading is increased 53–387% in Eln^−/−, Lox^−/−, and Fbln4^−/− aorta, indicating that not only elastin, but properly assembled and crosslinked elastic fibers, are necessary for low energy loss in the aorta.     

Vitamin D Receptor Controls Cell Stemness in Acute Myeloid Leukemia and in Normal Bone Marrow

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TRAIL Receptors Serve as Stress-Associated Molecular Patterns to Promote ER-Stress-Induced Inflammation

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Crystal structure of human PACRG in complex with MEIG1 reveals roles in axoneme formation and tubulin binding

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Genetic markers for identification of Patagonian toothfish and Antarctic toothfish

Fillet samples of the toothfish Dissostichus eleginoides and D. mawsoni can be distinguished readily by muscle proteins revealed by isoelectric focusing and mitochondrial DNA markers. The proteins also distinguish toothfish from other species marketed under similar trade names.     

The alkene monooxygenase from Xanthobacter Py2 is a binuclear non-haem iron protein closely related to toluene 4-monooxygenase

The genes encoding the six polypeptide components of the alkene monooxygenase from Xanthobacter Py2 have been sequenced. The predicted amino acid sequence of the first ORF shows homology with the iron binding subunits of binuclear non-haem iron containing monooxygenases including benzene monooxygenase, toluene 4-monooxygenase (>60% sequence similarity) and methane monooxygenase (>40% sequence similarity) and that the necessary sequence motifs associated with iron co-ordination are also present. Secondary structure prediction based on the amino acid sequence showed that the predominantly α-helical structure that surrounds the binuclear iron binding site was conserved allowing the sequence to be modelled on the co-ordinates of the methane monooxygenase α-subunit. Significant differences in the residues forming the hydrophobic cavity which forms the substrate binding site are discussed with reference to the differences in reaction specificity and stereospecificity of binuclear non-haem iron monooxygenases.     

Factors determining the reconstructive denaturation of proteins in sodium dodecyl sulfate solutions. Further circular dichroism studies on structural reorganization of seven proteins

The factors determining the onset and extent of reconstructive denaturation of proteins were considered by comparing circular dichroism (CD) data of seven proteins and previously published findings. The effects of sodium dodecyl sulfate (SDS) on the conformation of the following proteins were tested: lysozyme, the mitogens fromPhytolacca americana (fractions Pa2 and Pa4), lectin fromWistaria floribunda, ovine lutropin, a Bence Jones protein, and histone H2B. While the helix content of lysozyme was raised by SDS slightly, in the Bence Jones protein andW. floribunda lectin it increased from near zero to about 25–30%. In histone H2B the helix content was raised by SDS even to about 48%. However, no clear indication of helix formation could be observed in the mitogens and lutropin, even at low pH or 2.0–2.5. The tertiary structure of the proteins was perturbed by SDS. It was concluded that the reorganization of secondary structure of the proteins was favored by the following factors: (1) presence of helicogenic amino acid sequences in the protein, (2) availability of positively charged sites of the basic amino acids for interactions with the dodecyl ion, (3) absence of a large surplus of negatively charged sites on the surface of protein, and (4) absence of extensive disulfide cross-linking within the macromolecule. Both hydrophobic and electrostatic interactions occur in reconstructive denaturation, and the newly formed helices are stabilized by hydrophobic shielding by the alkyl chains of the alkyl sulfate.     

Identification of N5-methyl-N5-formyl-2,5,6-triamino-4-hydroxypyrimidine as a major adduct in rat liver DNA after treatment with the carcinogens, N,N-dimethylnitrosamine or 1,2-dimethylhydrazine

Human Tamm-Horsfall urinary glycoprotein from an individual of the blood group Sd(a+) phenotype was tritium-labelled by treatment with galactose oxidase and sodium boro[3H]hydride and was then digested with endo-beta-galactosidase. A series of dialysable, labelled fragments was released from which a pentasaccharide was isolated that strongly inhibited the agglutination of Sd(a+) red cells by human anti-Sda serum and hence contained the Sda determinant structure. Reduction, methylation analysis and sequential exo-glycosidase digestion established the structure of the pentasaccharide as: GalNAc beta(1 leads to 4)[NeuAc(2 leads to 3)]Gal beta(1 leads to 4)GlcNAc beta(1 leads to 3)Gal     

The binding of pentaammineruthenium (III) to RNase B and RNase A+d(pA)4 in the crystalline state

The binding of pentaammineruthenium (III) to ribonuclease A and B both free and complexed with d(pA)₄ has been examined in the crystalline state through the application of X-ray diffraction and difference Fourier techniques. In crystals of native RNase B, the reagent was observed to have many binding sites, some entirely electrostatic in nature and others consistent with coordination to histidine residues. The primary histidine in the latter case was 105 with 119 also partially substituted. In crystals of RNase A+d(pA)₄ complex only a single, extremely strong site of substitution was observed, and this was 2.4 Å from the native position of the imidazole ring of histidine 105. Thus, the results of these X-ray diffraction studies appear to be quite consistent with the findings of earlier NMR studies and with the results obtained in crystals of the gene 5 DNA binding protein.     

A Putative Calcium-Permeable Cyclic Nucleotide-Gated Channel, CNGC18, Regulates Polarized Pollen Tube Growth

A tip-focused Ca^2＋ gradient is tightly coupled to polarized pollen tube growth, and tip-localized influxes of extracellular Ca^2＋ are required for this process. However the molecular identity and regulation of the potential Ca^2＋ channels remains elusive. The present study has implicated CNGC18 （cyclic nucleotide-gated channel 18） in polarized pollen tube growth, because its overexpression induced wider and shorter pollen tubes. Moreover, CNGC18 overexpression induced depolarization of pollen tube growth was suppressed by lower extracellular calcium （[Ca^2＋]ex）. CNGC18-yellow fluorescence protein （YFP） was preferentially localized to the apparent post-Golgi vesicles and the plasma membrane （PM） in the apex of pollen tubes. The PM localization was affected by tip-localized ROP1 signaling. Expression of wild type ROP1 or an active form of ROP1 enhanced CNGC18-YFP localization to the apical region of the PM, whereas expression of RopGAP1 （a ROP1 deactivator） blocked the PM localization. These results support a role for PM-Iocalized CNGC18 in the regulation of polarized pollen tube growth through its potential function in the modulation of calcium influxes.