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31.
Lane MM Burke N Karreman R Wolfe KH O'Byrne CP Morrissey JP 《Antonie van Leeuwenhoek》2011,100(4):507-519
Kluyveromyces marxianus is homothallic hemiascomycete yeast frequently isolated from dairy environments. It possesses phenotypic traits such as enhanced
thermotolerance, inulinase production, and rapid growth rate that distinguish it from its closest relative Kluyveromyces lactis. Certain of these traits, notably fermentation of lactose and inulin to ethanol, make this yeast attractive for industrial
production of ethanol from inexpensive substrates. There is relatively little known, however, about the diversity in this
species, at the genetic, metabolic or physiological levels. This study compared phenotypic traits of 13 K. marxianus strains sourced from two European Culture Collections. A wide variety of responses to thermo, osmotic, and cell wall stress
were observed, with some strains showing multi-stress resistance. These traits generally appeared unlinked indicating that,
as with other yeasts, multiple resistance/adaptation pathways are present in K. marxianus. The data indicate that it should be possible to identify the molecular basis of traits to facilitate selection or engineering
of strains adapted for industrial environments. The loci responsible for mating were also identified by genome sequencing
and PCR analysis. It was found that K. marxianus can exist as stable haploid or diploid cells, opening up additional prospects for future strain engineering. 相似文献
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George Karreman 《Bulletin of mathematical biology》1953,15(2):161-165
A mechanism is described which accounts for the active transport of Na+ ions through a membrane. It is assumed that at one side of the membrane the ion combines with a carrier ion, the resulting
carrier compound then diffuses through the membrane and decomposes at the other side of the membrane. The free diffusion of
the ions is also taken into account. The time rate of accumulation of the ion in question at the latter side of the membrane
is calculated in terms of the concentrations of the ion at both sides of the membrane. 相似文献
35.
George Karreman 《Bulletin of mathematical biology》1971,33(4):483-495
A stochastic treatment of cooperative specific adsorption of ions at a linear chain of discrete sites leads to a set of differential
equations for the various probabilities involved in which the coefficients are determined by nearest neighbor interactions
and relative adsorption specificities of the ions for the sites. It is shown that the cooperative specific adsorption isotherm
derived earlier on the basis of statistical mechanics for essentially a very large number of sites can be obtained with maximum
deviations of only three per cent with this approach by considering only five sites. 相似文献
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38.
Stefan Schildknecht Hanne R. Gerding Christiaan Karreman Malte Drescher Hilal A. Lashuel Tiago F. Outeiro Donato A. Di Monte Marcel Leist 《Journal of neurochemistry》2013,125(4):491-511
Alpha‐synuclein (ASYN) is a major constituent of the typical protein aggregates observed in several neurodegenerative diseases that are collectively referred to as synucleinopathies. A causal involvement of ASYN in the initiation and progression of neurological diseases is suggested by observations indicating that single‐point (e.g., A30P, A53T) or multiplication mutations of the gene encoding for ASYN cause early onset forms of Parkinson's disease (PD). The relative regional specificity of ASYN pathology is still a riddle that cannot be simply explained by its expression pattern. Also, transgenic over‐expression of ASYN in mice does not recapitulate the typical dopaminergic neuronal death observed in PD. Thus, additional factors must contribute to ASYN‐related toxicity. For instance, synucleinopathies are usually associated with inflammation and elevated levels of oxidative stress in affected brain areas. In turn, these conditions favor oxidative modifications of ASYN. Among these modifications, nitration of tyrosine residues, formation of covalent ASYN dimers, as well as methionine sulfoxidations are prominent examples that are observed in post‐mortem PD brain sections. Oxidative modifications can affect ASYN aggregation, as well as its binding to biological membranes. This would affect neurotransmitter recycling, mitochondrial function and dynamics (fission/fusion), ASYN's degradation within a cell and, possibly, the transfer of modified ASYN to adjacent cells. Here, we propose a model on how covalent modifications of ASYN link energy stress, altered proteostasis, and oxidative stress, three major pathogenic processes involved in PD progression. Moreover, we hypothesize that ASYN may act physiologically as a catalytically regenerated scavenger of oxidants in healthy cells, thus performing an important protective role prior to the onset of disease or during aging. 相似文献
39.
Ulf R. Rapp Christian Korn Fatih Ceteci Christiaan Karreman Katharina Luetkenhaus Valentina Serafin Emanuele Zanucco Inês Castro Tamara Potapenko 《PloS one》2009,4(6)
Background
Metastasis is a process by which cancer cells learn to form satellite tumors in distant organs and represents the principle cause of death of patients with solid tumors. NSCLC is the most lethal human cancer due to its high rate of metastasis.Methodology/Principal Findings
Lack of a suitable animal model has so far hampered analysis of metastatic progression. We have examined c-MYC for its ability to induce metastasis in a C-RAF-driven mouse model for non-small-cell lung cancer. c-MYC alone induced frank tumor growth only after long latency at which time secondary mutations in K-Ras or LKB1 were detected reminiscent of human NSCLC. Combination with C-RAF led to immediate acceleration of tumor growth, conversion to papillary epithelial cells and angiogenic switch induction. Moreover, addition of c-MYC was sufficient to induce macrometastasis in liver and lymph nodes with short latency associated with lineage switch events. Thus we have generated the first conditional model for metastasis of NSCLC and identified a gene, c-MYC that is able to orchestrate all steps of this process.Conclusions/Significance
Potential markers for detection of metastasis were identified and validated for diagnosis of human biopsies. These markers may represent targets for future therapeutic intervention as they include genes such as Gata4 that are exclusively expressed during lung development. 相似文献40.
Isolation of a deoxycytidylate methyl transferase capable of protecting DNA uniquely against cleavage by endonuclease R.Aqu I (isoschizomer of Ava I). 总被引:6,自引:3,他引:3 下载免费PDF全文
A sequence-specific modification methylase (M.AquI) was isolated and purified from Agmenellum quadruplicatum (Synechococcus PCC 7002). This enzyme uniquely methylates the deoxycytidylate residue in the sequence *CYCGRG indicated by the asterisk. It was shown to protect DNA against cleavage by restriction endonucleases AvaI, SmaI and XhoI, which recognize the sequences CYCGRG, CCCGGG, and CTCGAG, respectively. 相似文献