Oxidative Stress in Caenorhabditis elegans: Protective Effects of Spartin

Troyer syndrome is caused by a mutation in the SPG20 gene, which results in complete loss of expression of the protein spartin. We generated a genetic model of Troyer syndrome in worms to explore the locomotor consequences of a null mutation of the Caenorhabditis elegans SPG20 orthologue, F57B10.9, also known as spg-20. Spg-20 mutants showed decreased length, crawling speed, and thrashing frequency, and had a shorter lifespan than wild-type animals. These results suggest an age-dependent decline in motor function in mutant animals. The drug paraquat was used to induce oxidative stress for 4 days in the animals. We measured survival rate and examined locomotion by measuring crawling speed and thrashing frequency. After 4 days of paraquat exposure, 77% of wild-type animals survived, but only 38% of spg-20 mutant animals survived. Conversely, animals overexpressing spg-20 had a survival rate of 95%. We also tested lifespan after a 1 hour exposure to sodium azide. After a 24 hour recovery period, 87% of wild type animals survived, 57% of spg-20 mutant animals survived, and 82% of animals overexpressing spg-20 survived. In the behavioral assays, spg-20 mutant animals showed a significant decrease in both crawling speed and thrashing frequency compared with wild-type animals. Importantly, the locomotor phenotype for both crawling and thrashing was rescued in animals overexpressing spg-20. The animals overexpressing spg-20 had crawling speeds and thrashing frequencies similar to those of wild-type animals. These data suggest that the protein F57B10.9/SPG-20 might have a protective role against oxidative stress.     

Class 1 Integrons and Antibiotic Resistance of Clinical Acinetobacter calcoaceticus–baumannii Complex in Poznań, Poland

Sixty-three clinical isolates of Acinetobacter calcoaceticus–baumannii complex were analyzed for the presence of integrons and antimicrobial resistance. Class 1 integrons were detected in 40 (63.5 %) isolates. None of them had class 2 or class 3 integrons. The majority of the integrons contained aacC1–orfA–orfB–aadA1 gene cassette array. The presence of integrons was associated with the increased frequency of resistance to 12 of 15 antimicrobials tested, multi-drug resistance phenotype, and the overall resistance ranges of the strains.     

The species-specific cell-binding site of the aggregation factor from the sponge Microciona prolifera is a highly repetitive novel glycan containing glucuronic acid, fucose, and mannose

Species-specific adhesion of dissociated cells from the marine sponge Microciona prolifera is mediated by a Mr = 2 x 10(7) proteoglycan-like aggregation factor (MAF) via two highly polyvalent functional domains, a cell-binding and a self-interaction domain. Glycopeptide N-glycosidase F release of a major glycan of Mr = 6.3 gamma 10(3) (G-6) from the MAF protein core resulted in the loss of cell binding activity, indicating a role of this polysaccharide molecule in MAF-cell association. The G-6 glycan was isolated and purified after complete Pronase digestion of MAF using gel electrophoresis, gel filtration, and ion exchange chromatography. Quantification of the amount of carbohydrate recovered in G-6 showed that one MAF molecule has about 950 repeats of this glycan. In its monomeric state G-6 did not display any measurable binding to cells (K alpha less than or equal to 10(3) M-1). Intermolecular cross-linking of the G-6 glycan with glutaraldehyde resulted, however, in the concomitant recovery of polyvalency (about 2200 repeats of G-6 per polymer of Mr greater than or equal to 1.5 x 10(7) and species-specific high cell binding affinity (K alpha = 1.6 x 10(9) M-1) but not of the MAF-MAF self-interaction activity. Thus, the G-6 glycan is the multiple low affinity cell-binding site involved in cell-cell recognition and adhesion of sponge cells. The G-6 glycan has 7 glucuronic acids, 3 fucoses, 2 mannoses, 5 galactoses, 14 N-acetylglucosamines, 2 sulfates, and 1 asparagine. Such a unique chemical composition indicates a new type of structure which includes features of glycosaminolycans and N-linked polysaccharides.     

Cell-mediated immunity in experimental allergic encephalomyelitis: cross reactivity between myelin basic protein and mycobacteria antigens.

Guinea pigs injected with Freund's incomplete adjuvant emulsified with guinea pig spinal cord, purified guinea pig myelin basic protein, or human myelin basic protein showed dermal reactivity to both of the basic proteins as well as to mycobacteria antigens. Animals receiving only mycobacteria antigens expressed dermal reactivity to the sensitizing antigen in addition to basic protein. This cross reactivity may help explain the role of mycobacteria in inducing and protecting against EAE, and may have important implications concerning human demyelinating diseases.     

Rapid chromosome territory relocation by nuclear motor activity in response to serum removal in primary human fibroblasts

Background  

Radial chromosome positioning in interphase nuclei is nonrandom and can alter according to developmental, differentiation, proliferation, or disease status. However, it is not yet clear when and how chromosome repositioning is elicited.