Spielberger JC  Moody AD  Watson WH 《Journal of cellular biochemistry》2008,104(5):1879-1889

Reactive oxygen species (ROS) were once viewed only as mediators of toxicity, but it is now recognized that they also contribute to redox signaling through oxidation of specific cysteine thiols on regulatory proteins. Cells in sparse cultures have increased ROS relative to confluent cultures, but it is not known whether protein redox states are affected under these conditions. The purpose of the present study was to determine whether culture conditions affect the redox state of thioredoxin-1 (Trx1), the protein responsible for reducing most oxidized proteins in the cytoplasm and nucleus. The results showed that Trx1 was more oxidized in sparse HeLa cell cultures than in confluent cells. The glutathione pool was also more oxidized, demonstrating that both of the major cellular redox regulating systems were affected by culture density. In addition, the total amount of Trx1 protein was lower and the subcellular distribution of Trx1 was different in sparse cells. Trx1 in sparse cultures was predominantly nuclear whereas it was predominantly cytoplasmic in confluent cultures. This localization pattern was not unique to HeLa cells as it was also observed in A549, Cos-1 and HEK293 cells. These findings demonstrate that Trx1 is subject to changes in expression, redox state and subcellular localization with changing culture density, indicating that the redox environments of the cytoplasm and the nucleus are distinct and have different requirements under different culture conditions.  相似文献   

    

Long SC  Arango P C  Plummer JD 《Canadian journal of microbiology》2005,51(5):413-422

With increased focus on watershed protection under the Surface Water Treatment Rule, indicators that discriminate among sources of microbial inputs (microbial source tracking) are needed to supplement the quantitative information provided by total and fecal coliform measurements for drinking water monitoring. Bifidobacteria are found in the digestive tract and feces of humans and other animals, and also in sewage. Sorbitol is a food additive used exclusively in food intended for human consumption. Therefore, the presence of sorbitol-fermenting Bifidobacteria in environmental waters can be indicative of sources of human fecal contamination. A series of media were evaluated using ATCC cultures of B. breve and B. adolescentis, feces from different animals, and domestic wastewater samples. The media evaluated were Human Bifid Sorbitol agar (HBSA), modified Human Bifid Sorbitol agar, Beerens Medium, modified Beerens Medium, Reinforced Clostridial agar, BIM-25 Medium, and modified BIM-25 Medium. Variables such as sample preservation, incubation time, different pH indicators, plating technique, and discontinuous exposure to sorbitol were also evaluated. A series of biochemical tests were used to confirm positive colonies enumerated on the various media. Membrane filtration and enumeration of sodium sulfite preserved samples on HBSA containing bromocresol purple using loose lidded plates for 48 h provided the best recoveries for presumptive positive colonies. A number of sorbitol-fermenters that were not Bifidobacteria were able to grow on all media tested, resulting in false-positives. Therefore, plating on HBSA should be followed by a confirmation step when monitoring for sorbitol-fermenting Bifidobacteria in environmental waters. A year-long sampling survey of a managed reservoir in Massachusetts provided field validation of the proposed methodology for sorbitol-fermenting Bifidobacteria as a human-related source tracking indicator tool.  相似文献   

    

Foronjy RF  Okada Y  Cole R  D'Armiento J 《American journal of physiology. Lung cellular and molecular physiology》2003,284(5):L727-L737

Mice with lung-specific expression of human matrix metalloproteinase-1 (MMP-1) develop emphysematous changes similar to those seen in smoking-induced emphysema in humans. Morphometric analyses of three transgenic lines [homozygous colony (Col) 34, Col 50, and Col 64] with varying temporal expression of MMP-1 were undertaken to determine the validity of this animal as a model of adult-onset emphysema. Line 50 mice, which have early expression of MMP-1 (14 days postconception), exhibited morphometric changes by 5 days of age. In contrast, homozygous line 34 and 64 with delayed expression (birth and 2 wk of age) were normal up until 4 wk of age when progressive changes in their mean linear intercept were first noted. In contrast, heterozygous mice from line 34 with lower transgene expression did not develop emphysema until 1 yr of age. The changes in mean linear intercept coincided with an increase in lung compliance. Emphysema in these mice was associated with decreased immunostaining for type III collagen within the alveolar septa. This study provides evidence that MMP-1 induces progressive adult-onset emphysema by the selective degradation of type III collagen within the alveolar wall.  相似文献   

  总被引：2，自引：0，他引：2  

Hoarau G  Holla S  Lescasse R  Stam WT  Olsen JL 《Molecular biology and evolution》2002,19(12):2261-2264

The general assumption that mitochondrial DNA (mtDNA) does not undergo recombination has been challenged recently in invertebrates. Here we present the first direct evidence for recombination in the mtDNA of a vertebrate, the flounder Platichthys flesus. The control region in the mtDNA of this flatfish is characterized by the presence of a variable number of tandem repeats and a high level of heteroplasmy. Two types of repeats were recognized, differing by two C-T point mutations. Most individuals carry a pure \"C\" or a pure \"T\" array, but one individual showed a compound \"CT\" array. Such a compound array is evidence for recombination in the mtDNA control region from the flounder.  相似文献   

    

Violaine Bonnefoy  Jeanine Ratouchniak  Francis Blasco  Marc Chippaux 《FEMS microbiology letters》1997,147(1):147-149

The two membrane-bound respiratory nitrate reductases of Escherichia coli are encoded by distinct operons at two different loci, chlC and chlZ, on the chromosome. The chlZ locus includes a narK homologue, narU, encoding a nitrite extrusion protein, and narZYWV encoding nitrate reductase Z. No apparent homologue to the narXL operon has been found. Homology between narU and narK on the one hand and narZYWV and narGHJI on the other hand is limited to the coding regions.  相似文献   

    

Sandra C. Lindstrom  Jeanine L. Olsen  Wytze T. Stam 《Journal of phycology》1996,32(3):457-468

Molecular phylogenetic studies on the evolution of the red algae indicate that this ancient division has many lineages that have recently undergone radiations. One such example is the cold–temperate family Palmariaceae. In this study, sequences from the ribosomal DNA internal transcribed spacer regions were compared among ten species in the Palmariaceae from both Atlantic and Pacific sites, Phylogenetic analyses of sequence data, in which Rhodophysema georgii Batters was used as outgroup and root, indicate a radiation into four clades, three of which contain species of “Palmaria” and the fourth species of Halosaccion. Palmaria palmata (L.) Kuntze, the type and only North Atlantic species in the genus, stands apart from all remaining species in the family and terminates the most basal branch in the rooted tree. The three more derived clades have radiated mainly in the North Pacific. Southern Ocean Palmaria and North Atlantic Devaleraea are hypothesized to have invaded from separate but closely related North Pacific ancestors. The ease with which sequences could be aligned combined with an unsaturated transition: transversion ratio and modest divergence involving predominantly point mutations suggests that the initial radiation is relatively recent (late Miocene–Pliocene) and that the Devaleraea–Palmaria clade is even more recent (late Pliocene–Pleistocene).  相似文献   

    

Wiebe H. C. F. Kooistra  Wytze T. Stam  Jeanine L. Olsen  Chris van den Hoek 《Journal of phycology》1992,28(5):660-668

Nucleotides were compared at 988 sites, spanning both internal transcribed spacers (ITS1 and ITS2) of the nuclear ribosomal DNA, among 17 isolates of the green alga Cladophoropsis membranacea (Hofman Bang ex C. Agardh) Boergesen and two isolates of Struvea anastomosans (Harvey) Piccone and Grunow. Collections were made from Bonaire, Curaçao, St. Croix, the Canary Islands, the Cape Verde Islands, Mauritania, Syria, the Red Sea, Okinawa, and Hawaii. Two nucleotide substitutions were found between the sequenced coding regions of C. membranacea and S. anastomosans. Of the 720 nucleotides compared in ITS1 and ITS2, an average of 6.7% sequence divergence was found within C. membranacea and 17.4% between C. membranacea and S. anastomosans. Sequences were analyzed using maximum parsimony. Phylogenetic hypotheses were compared with the biogeographic hypothesis of an east-west Tethyan vicariance. Results of the study allow the identification of widely dispersed biogeographic populations, the identification of an underlying Tethyan imprint, and support for the hypothesis that dispersal has occurred between the Caribbean and the tropical eastern Atlantic. These results demonstrate the usefulness of ITS sequences at the sub-specific level in C. membranacea.  相似文献