DE-cadherin, a core component of the adherens junction complex modifies subcellular localization of the Drosophila gap junction protein innexin2

The Drosophila innexin multigene family of gap junction encoding proteins consists of eight family members whose function in epithelial morphogenesis is mostly unknown. We have recently shown that innexin2 plays a crucial role in the organization of embryonic epithelia. Innexin2 protein accumulates in the epidermis in the apico-lateral membrane domain and colocalizes with core proteins of adherens junctions, such as DE-cadherin and Armadillo, the ss -catenin homolog. Innexin2 localization is altered in both armadillo and DE-cadherin mutants Biochemical interaction studies point to a direct interaction of DE-cadherin and Armadillo with innexin2 suggesting a close link between gap junction and adherens junction biogenesis. We have used the Drosophila Schneider cell tissue culture system to further study the interaction of innexin2 with DE-cadherin. Our results provide evidence that DE-cadherin may be a key component to control trafficking, and localization of Innexin2 to the plasma membrane.     

Differential responses to growth factors by normal human mesothelial cultures from individual donors

A significant interindividual variation in the growth rates is found in normal cultured human mesothelial (NHM) cells derived from different donors. This variation is observed when the mesothelial cells are incubated in medium containing serum and when the potencies of several separate growth factors are measured by using defined media. Depending on the donor, gamma-interferon and interleukin-2 can be toxic, have no effect, or stimulate the growth rate of NHM cells. Cultured NHM cells can be induced to multiply by growth factors that are released by activated macrophages. Thus, interindividual variation in NHM cell growth control could play a role in the pathogenesis of mesothelioma for a person exposed to asbestos.     

Characterization of different decomposition stages of biowaste using FT-IR spectroscopy and pyrolysis-field ionization mass spectrometry

The decomposition stage and stabilization of organic matter in biowaste (mixture of yard waste and kitchen waste), originating from an open windrow process, were investigated using Fourier transform infrared (FT-IR) spectroscopy and pyrolysis-field ionization mass spectrometry (Py-FIMS). These investigations provided detailed information about chemical constituents and their behavior during the composting process. The chemical compounds were classified by their molecular signals in Py-FIMS. Multivariate statistical analysis revealed, that during the composting process, the group containing lipids, fatty acids and other chemical compounds with aliphatic skeletons changed the most. Corresponding with Py-FIMS findings changes were observed in absorbance bands of infrared spectra that reflect this group of organic compounds: the aliphatic methylene bands at 2925 and 2850cm^-1, the band of C=O vibrations of carboxylates at 1640cm^-1, the O=H in-plane bend of carboxylic acids, the CO₂ stretch of carboxylates and the CH₂ group of alkanes at around 1430cm^-1. During decomposition these bands decreased up to a steady level that indicated stabilization. The band at 1260–1240cm^-1 that can be assigned to the C=O stretch of carboxylic acids or to the C=N stretch of amides and the band of aromatic amines at 1320cm^-1 disappeared completely. The nitrate band at 1384cm^-1 appeared at a later stage of the composting process. The relative increase of chemical compounds like moieties of lignin, humic acids and tannins in the composted material contributed to the aromatic C=C band at around 1640cm^-1.     

RGD-dependent binding of procathepsin X to integrin alphavbeta3 mediates cell-adhesive properties

Secreted lysosomal cysteine proteases (cathepsins) are involved in degradation and remodeling of the extracellular matrix, thus contributing to cell adhesion and migration. Among the eleven human lysosomal cysteine proteases, only procathepsin X contains an RGD motif located in a highly exposed region of the propeptide, which may allow binding of the proenzyme to RGD-recognizing integrins. Here, we have tested procathepsin X for cell-adhesive properties and found that it supports integrin alpha(v)beta(3)-dependent attachment and spreading of human umbilical vein endothelial cells. Using site-directed mutants of procathepsin X, we proved that this effect is mediated by the RGD sequence within the proregion of the protease. Endogenous procathepsin X is transported to the plasma membrane, accumulates in vesicles at lamellipodia of the human umbilical vein endothelial cell, and is partly associated with the cell surface, as shown by immunofluorescence. In addition, procathepsin X is partly co-localized with integrin beta(3), as detected by immunogold electron microscopy. A direct interaction between endogenous procathepsin X and alpha(v)beta(3) was demonstrated by co-immunoprecipitation. Moreover, surface plasmon resonance analysis revealed significant and RGD-dependent binding of procathepsin X to integrin alpha(v)beta(3). Our results provide for the first time evidence that the extracellular function of cathepsin X may include binding to integrins thereby modulating the attachment of migrating cells to ECM components.     

Relationship between structure, dynamics and function of hydrated purple membrane investigated by neutron scattering and dielectric spectroscopy

We investigated the influence of hydration water on the relationship between structure, dynamics and function in a biological membrane system. For the example of the purple membrane (PM) with its protein bacteriorhodopsin (BR), a light-driven proton pump, complementary information from neutron diffraction, quasi-elastic neutron scattering (QENS) and dielectric spectroscopy will form a comprehensive picture of the structural and dynamic behavior of the PM in the temperature range between 150 and 290 K. Temperature- and humidity-dependent changes in the membrane system influence the accessibility of the different photocycle intermediates of BR. The melting of the 'freezing bound water' between 220 and 250 K could be related to the transition from the M1 to the M2 intermediate, which represents the key step in the photocycle. The dynamic transition in the vicinity of 180 K was shown to be necessary to ensure that the M1 intermediate can be populated and that the melting of crystallized bulk water above 255 K enables the completion of the photocycle.     

A high-resolution linkage map for the Z chromosome in chicken reveals hot spots for recombination

A comprehensive linkage map for chicken chromosome Z was constructed as the result of a large-scale screening of single nucleotide polymorphisms (SNPs). A total of 308 SNPs were assigned to Z based on the genotype distribution among 182 birds representing several populations. A linkage map comprising 210 markers and spanning 200.9 cM was established by analyzing a small Red junglefowl/White Leghorn intercross. There was excellent agreement between the linkage map for Z and a recently released assembly of the chicken genome (May 2006). Almost all SNPs assigned to chromosome Z in the present study are on Z in the new genome assembly. The remaining 12 loci are all found on unassigned contigs that can now be assigned to Z. The average recombination rate was estimated at 2.7 cM/Mb but there was a very uneven distribution of recombination events with both cold and hot spots of recombination. The existence of one of the major hot spots of recombination, located around position 39.4 Mb, was supported by the observed pattern of linkage disequilibrium. Thirteen markers from unassigned contigs were shown to be located on chromosome W. Three of these contigs included genes that have homologues on chromosome Z. The preliminary assignment of three more genes to the gene-poor W chromosome may be important for studies on the mechanism of sex determination and dosage compensation in birds.     

Presence of Pleurotus ostreatus in Patagonia,Argentina

Specimens belonging to the genus Pleurotus were collected growing on fallen trunks of Araucaria araucana, a native tree with a poorly known mycoflora, which grows in Patagonia, Argentina. Fruitbodies were produced in culture on sawdust from an isolated strain. Interspecific pairing tests performed between mating types of Pleurotus from Patagonia and tester strains of P. pulmonarius and P. ostreatus showed the Patagonia strain to be 100% compatible with P. ostreatus and incompatible with P. pulmonarius. Dikaryons obtained on sawdust were fertile, since they were able to produce fruitbodies and viable spores. This is the first documented record of P. ostreatus from Argentina and the first gilled fungus found growing on Araucaria araucana.     

Role of the amino-terminal extrahelical region of type I collagen in directing the 4D overlap in fibrillogenesis

The amino-terminal telopeptide of the collagen α1(I) chain has a highly conserved sequence. This sequence was analyzed by the Chou-Fasman criteria, and a folded β-sheet conformation, including a β-turn, was predicted. This folded “hairpin” region favors both ionic and hydrophobic intermolecular interactions with α1(I) chain residues 930–938 on a neighboring, end-overlapped molecule. An end-overlap interaction of this nature could direct the initial step in fibril formation. The predicted structure also places the potential crosslink-forming lysyl residue, 9^N, in a unique site at the β-turn end of the telopeptide.