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Alien invertebrates transported accidentally to the Polish Antarctic Station in cargo and on fresh foods
Get PDFDuring three austral summer seasons cargo, expeditioner clothes and equipment
of the Polish Antarctic Expedition were examined for the presence of alien propagules. De−
tailed inspections were undertaken at the station buildings, searching for any invertebrates.
During each austral summer fresh fruits and vegetables were also inspected. A total of 359
invertebrates and their remains were found in cargo transported to Arctowski Station, or
caught in the station’s facilities. The majority of samples were classified as cultivation pests
(26%), food pests (43%), wood−destroying pests (4%), domestic insects and arachnids
(15%). Through supply of the research station a wide range of alien organisms can be acci−
dentally transported and ultimately introduced to the Antarctic. This study has clearly dem−
onstrated that almost all cargo items can be a potential vector for alien organisms. Species
from a broad range of biological groups can be transported to the Antarctic and remain in a
viable state
Theoretical model explaining the relationship between the molecular mass and the activation energy of the enzyme revealed by a large-scale analysis of bioinformatics data.
Get PDFA general dependence of the enzyme catalytic rate on its mass was revealed when a statistical analysis of 17065 records from the EMP database was performed. The estimated activation energy of the catalytic process decreases asymptotically with the enzyme molecular mass increase. The proposed theoretical model postulates the existence of an intermediate complex of the enzyme and the departing product. It allows for the explanation of the discovered mass-energy relationship, as an effect of the global enzyme-product interactions during complex dissociation. Fitted parameters of the model seem to be in agreement with those widely accepted for the van der Waals energy of molecular interactions. Their values also agree with the picture of the hydrogen bonding in the catalytic process and suggest that surface walk can be the favorable way of the product departure
Reduced colonic microbial diversity is associated with colitis in NHE3-deficient mice
No full textChronic inflammation and enteric infections are frequently associated with epithelial Na(+)/H(+) exchange (NHE) inhibition. Alterations in electrolyte transport and in mucosal pH associated with inflammation may represent a key mechanism leading to changes in the intestinal microbial composition. NHE3 expression is essential for the maintenance of the epithelial barrier function. NHE3(-/-) mice develop spontaneous distal chronic colitis and are highly susceptible to dextran sulfate (DSS)-induced mucosal injury. Spontaneous colitis is reduced with broad-spectrum antibiotics treatment, thus highlighting the importance of the microbiota composition in NHE3 deficiency-mediated colitis. We herein characterized the colonic microbiome of wild-type (WT) and NHE3(-/-) mice housed in a conventional environment using 454 pyrosequencing. We demonstrated a significant decrease in the phylogenetic diversity of the luminal and mucosal microbiota of conventional NHE3(-/-) mice compared with WT. Rederivation of NHE3(-/-) mice from conventional to a barrier facility eliminated the signs of colitis and decreased DSS susceptibility. Reintroduction of the conventional microflora into WT and NHE3(-/-) mice from the barrier facility resulted in the restoration of the symptoms initially described in the conventional environment. Interestingly, qPCR analysis of the microbiota composition in mice kept in the barrier facility compared with reconventionalized mice showed a significant reduction of Clostridia classes IV and XIVa. Therefore, the gut microbiome plays a prominent role in the pathogenesis of colitis in NHE3(-/-) mice, and, reciprocally, NHE3 also plays a critical role in shaping the gut microbiota. NHE3 deficiency may be a critical contributor to dysbiosis observed in patients with inflammatory bowel disease
The spectrum of PLP1 gene mutations in patients with the classical form of the Pelizaeus-Merzbacher disease.
Get PDFUterine and umbilical blood flow measurements are reviewed in terms of studies carried out in uncomplicated human pregnancies. The review includes the perspective of how those estimates of flow fit with current knowledge of human fetal O2 consumption and uterine O2 and glucose consumption. From the consideration of both the O2 data and the flow measurements, we conclude that the best estimates for mean umbilical blood flow at term range between 120 and 145 ml•min-1•(kg fetus)-1. The uterine flow estimate from physiologic data would equate to ~270 ml•min-1•(kg fetus)-1. This estimate, based upon estimates of uterine O2 and glucose consumption, is much higher than some estimates made by imaging techniques. The reasons for this discrepancy are not yet established. However, given the enormous variability in uterine flow measurements made with imaging techniques, it is clear that more research into improvement in these non-invasive approaches is still required and all current estimates of uterine flow must be regarded as rather crude trials
Maf1, repressor of tRNA transcription, is involved in the control of gluconeogenetic genes in Saccharomyces cerevisiae
Get PDFMaf1 is a negative regulator of RNA polymerase III (Pol III) in yeast. Maf1-depleted cells manifest elevated tRNA transcription and inability to grow on non-fermentable carbon source, such as glycerol. Using genomic microarray approach, we examined the effect of Maf1 deletion on expression of Pol II-transcribed genes in yeast grown in medium containing glycerol. We found that transcription of FBP1 and PCK1, two major genes controlling gluconeogenesis, was decreased in maf1Δ cells.
FBP1 is located on chromosome XII in close proximity to a tRNA-Lys gene. Accordinglywe hypothesized that decreased
FBP1 mRNA level could be due to the effect of Maf1 on tgm silencing (tRNA gene mediated silencing). Two approaches were used to verify this hypothesis. First, we inactivated tRNA-Lys gene on chromosome XII by inserting a deletion cassette in a control wild type strain and in maf1Δ mutant. Second, we introduced a pointmutation in the promoter of the tRNA-Lys gene cloned with the adjacent FBP1 in a plasmid and expressed in fbp1Δ or fbp1Δ maf1Δ cells. The levels of FBP1mRNA were determined by RT-qPCR in each strain. Although the inactivation of the chromosomal tRNA-Lys gene increased expression of the neighboring FBP1, the mutation preventing transcription of the plasmid-born tRNA-Lys gene had no significant effect on FBP1 transcription. Taken together, those results do not support the concept of tgm silencing of FBP1. Other possible mechanisms are discussed
An interplay between transcription, processing, and degradation determines tRNA levels in yeast
Get PDFtRNA biogenesis in yeast involves the synthesis of the initial transcript by RNA polymerase III followed by processing and controlled degradation in both the nucleus and the cytoplasm. A vast landscape of regulatory elements controlling tRNA stability in yeast has emerged from recent studies.Diverse pathways of tRNA maturation generate multiple stable and unstable intermediates. A significant
impact on tRNA stability is exerted by a variety of nucleotide modifications. Pre-tRNAs are targets of exosome-dependent surveillance in the nucleus. Some tRNAs that are hypomodified or bear specific destabilizing mutations are directed to the rapid tRNA decay pathway leading to 5�→3� exonucleolytic degradation by Rat1 and Xrn1. tRNA molecules are selectively marked for degradation by a double CCA at their 3� ends. In addition, under different stress conditions, tRNA half-molecules can be generated by independent endonucleolytic cleavage events. Recent studies reveal unexpected relationships between the subsequent steps of tRNA biosynthesis and the mechanisms controlling its quality and turnover
Mutations in the PLP1 gene residue p. Gly198 as the molecular basis of Pelizeaus-Merzbacher phenotype.
No full textPelizaeus-Merzbacher disease (PMD) and spastic paraplegia type 2 (SPG2) are rare X-linked allelic disorders caused by mutations in the PLP1 gene, encoding the main component of myelin, proteolipid protein 1 (PLP1). Various types of mutations, acting through different molecular mechanism, cause the diseases. Duplications of variable size at Xq22.2, containing the entire PLP1, are responsible for more than 50% of PMD cases. Other causes of PMD include point mutations, gene deletions and triplications. There is a spectrum of PLP1-related disorders with some correlation between the type of mutation and phenotype. Generally the missense mutations cause the more severe forms of the disease, the most common PLP1 duplications, result in the classical PMD whereas deletions and null mutations in mild form of PMD and SPG2. We present a patient with c.593G>A substitution in the exon 4 of the PLP1 gene causing a novel missense mutation p.Gly198Asp, finally diagnosed as PMD but showing an atypical MRI picture
Method and platform standardization in MRM-based quantitative plasma proteomics.
Get PDFThere exists a growing demand in the proteomics community to standardize experimental methods and liquid chromatography-mass spectrometry (LC/MS) platforms in order to enable the acquisition of more precise and accurate quantitative data. This necessity is heightened by the evolving trend of verifying and validating candidate disease biomarkers in complex biofluids, such as blood plasma, through targeted multiple reaction monitoring (MRM)-based approaches with stable isotope-labeled standards (SIS). Considering the lack of performance standards for quantitative plasma proteomics, we previously developed two reference kits to evaluate the MRM with SIS peptide approach using undepleted and non-enriched human plasma. The first kit tests the effectiveness of the LC/MRM-MS platform (kit #1), while the second evaluates the performance of an entire analytical workflow (kit #2). Here, these kits have been refined for practical use and then evaluated through intra- and inter-laboratory testing on 6 common LC/MS platforms. For an identical panel of 22 plasma proteins, similar concentrations were determined, regardless of the kit, instrument platform, and laboratory of analysis. These results demonstrate the value of the kit and reinforce the utility of standardized methods and protocols
Sugar availability modulates polyisoprenoid and phytosterol profiles in Arabidopsis thaliana hairy root culture.
Get PDFSugars are recognized as signaling molecules regulating the biosynthesis of secondary metabolites in plants. Here, a modulatory effect of sugars on dolichol and phytosterol profiles was noted in the hairy roots of Arabidopsis thaliana. Arabidopsis roots contain a complex dolichol mixture comprising three groups ('families') of dolichols differing in the chain-length. These dolichols, especially the longest ones are accompanied by considerable amounts of polyprenols of the same length. The spectrum of polyisoprenoid alcohols, i.e. dolichols and polyprenols, was dependent on sugar type (glucose or sucrose) and its concentration in the medium. Among the long-chain dolichols Dol/Pren-20 (dolichol or prenol molecule composed of 20 isoprene residues) and Dol/Pren-23 were the main components at 0.5% and 2% glucose, respectively. Moreover, the ratio of polyprenols versus respective dolichols was also modulated by sugar in this group of polyisoprenoids, with polyprenols dominating at 3% sucrose and dolichols at 2% glucose. Glucose concentration affected the expression level of genes encoding cis-prenyltransferases, enzymes responsible for elongation of the polyisoprenoid chain. The most abundant phytosterols of the A. thaliana roots, β-sitosterol, stigmasterol and campesterol, were accompanied by corresponding stanols and traces of brassicasterol, stigmast-4,22-dien-3-one and stigmast-4-en-3-one. Similar to the polyisoprenoids, sterol profile responded to the sugar present in the medium, β-sitosterol dominating in roots grown on 3% or lower glucose concentrations and stigmasterol in 3% sucrose. These results indicate an involvement of sugar signaling in the regulation of cis-prenyltransferases and phytosterol pathway enzymes
