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991.
Muhammad Asghar Staffan Bensch Maja Tarka Bengt Hansson Dennis Hasselquist 《Proceedings. Biological sciences / The Royal Society》2015,282(1799)
In a broad range of species—including humans—it has been demonstrated that telomere length declines throughout life and that it may be involved in cell and organismal senescence. This potential link to ageing and thus to fitness has triggered recent interest in understanding how variation in telomere length is inherited and maintained. However, previous studies suffer from two main drawbacks that limit the possibility of understanding the relative importance of genetic, parental and environmental influences on telomere length variation. These studies have been based on (i) telomere lengths measured at different time points in different individuals, despite the fact that telomere length changes over life, and (ii) parent–offspring regression techniques, which do not enable differentiation between genetic and parental components of inheritance. To overcome these drawbacks, in our study of a songbird, the great reed warbler, we have analysed telomere length measured early in life in both parents and offspring and applied statistical models (so-called ‘animal models'') that are based on long-term pedigree data. Our results showed a significant heritability of telomere length on the maternal but not on the paternal side, and that the mother''s age was positively correlated with their offspring''s telomere length. Furthermore, the pedigree-based analyses revealed a significant heritability and an equally large maternal effect. Our study demonstrates strong maternal influence on telomere length and future studies now need to elucidate possible underlying factors, including which types of maternal effects are involved. 相似文献
992.
More potent, but less known than IP3 that liberates Ca2+ from the ER, NAADP releases Ca2+ from acidic stores. The notion that TPC channels mediate this Ca2+ release was questioned recently by studies suggesting that TPCs are rather PI(3,5)P2‐activated Na+ channels. Ruas et al (2015) now partially reconcile these views by showing that TPCs significantly conduct both cations and confirm their activation by both NAADP and PI(3,5)P2. They attribute the failure of others to observe TPC‐dependent NAADP‐induced Ca2+ release in vivo to inadequate mouse models that retain partial TPC function. 相似文献
993.
John Achenbach Michael Jahnz Lucas Bethge Krisztina Paal Maria Jung Maja Schuster Renate Albrecht Florian Jarosch Knud H. Nierhaus Sven Klussmann 《Nucleic acids research》2015,43(12):5687-5698
Key components of the translational apparatus, i.e. ribosomes, elongation factor EF-Tu and most aminoacyl-tRNA synthetases, are stereoselective and prevent incorporation of d-amino acids (d-aa) into polypeptides. The rare appearance of d-aa in natural polypeptides arises from post-translational modifications or non-ribosomal synthesis. We introduce an in vitro translation system that enables single incorporation of 17 out of 18 tested d-aa into a polypeptide; incorporation of two or three successive d-aa was also observed in several cases. The system consists of wild-type components and d-aa are introduced via artificially charged, unmodified tRNAGly that was selected according to the rules of ‘thermodynamic compensation’. The results reveal an unexpected plasticity of the ribosomal peptidyltransferase center and thus shed new light on the mechanism of chiral discrimination during translation. Furthermore, ribosomal incorporation of d-aa into polypeptides may greatly expand the armamentarium of in vitro translation towards the identification of peptides and proteins with new properties and functions. 相似文献
994.
Raphael?N.?Vuille-dit-Bille Simone?M.?Camargo Luca?Emmenegger Tom?Sasse Eva?Kummer Julia?Jando Qeumars?M.?Hamie Chantal?F.?Meier Schirin?Hunziker Zsofia?Forras-Kaufmann Sena?Kuyumcu Mark?Fox Werner?Schwizer Michael?Fried Maja?Lindenmeyer Oliver?G?tze Fran?ois?VerreyEmail author 《Amino acids》2015,47(4):693-705
995.
996.
The replacement of O2 with CO was studied on cobalt—iron hemoglobin hybrids. Both proto- and meso-cobalt hemes were used for the reconstitution. In the oxy quaternary conformation no difference is observed between α- and β-subunits when only proto hemes are present in the hybrid (k4 = 30 s?1, k′4/l′4 = 2.5). If Co-meso heme is present on the β-chains the binding properties of the partner subunit are modified (k′4/l′4 = 4). 相似文献
997.
Biochemical Genetics of the Cryptic Gene System for Cellobiose Utilization in Escherichia coli K12 总被引:10,自引:4,他引:6 下载免费PDF全文
The cellobiose catabolic system of Escherichia coli K12 is being used to study the role of cryptic genes in microbial evolution. Wild-type E. coli K12 do not utilize the beta-glucoside sugars, arbutin, salicin and cellobiose. A Cel+ (cellobiose utilizing) mutant which grows on cellobiose, arbutin, and salicin was isolated previously from wild-type E. coli K12. Biochemical assays indicate that a cel structural gene (celT) specifies a single transport protein that is a beta-glucoside specific enzyme of the phosphoenolpyruvate-dependent phosphotransferase system. The transport protein phosphorylates beta-glucosides at the expense of phosphoenolpyruvate. A single phosphoglucosidase, specified by celH, hydrolyzes phosphorylated cellobiose, arbutin, and salicin. The genes of the cel system are expressed constitutively in the Cel+ mutant, whereas they are not expressed at a detectable level in the wild-type strain. The transport and hydrolase genes are simultaneously silenced or simultaneously expressed and thus constitute an operon. Cel+ strains which fail to utilize one or more beta-glucosides express the transport system at a lower level than do Cel+ strains which grow on all three beta-glucosides. Other strains inducibly express a gene which specifies transport of arbutin but not the other beta-glucosides. The arbutin transport gene, arbT, maps outside of the cel locus. 相似文献
998.
Dr. John N. Sieburth Paul W. Johnson Maja A. Eberhardt Michael E. Sieracki Mary Lidstrom David Laux 《Current microbiology》1987,14(5):285-293
Methane enrichment of twenty-three 100-ml portions of seawater from three stations in the Sargasso Sea yielded the same obligate type I methanotroph. It is pigmented white, requires NaCl, grows well in seawater with either methane or methanol, but not on other C1 compounds nor on C–C bonded organic matter, and it uses either ammonia or nitrate but not dinitrogen as a nitrogen source. Formaldehyde is produced in marked amounts from methanol. Growth occurs at 20° and 30°C but not at 10°C and is inhibited in natural sunlight. Representative isolates from each hydrographic station assimilate one-carbon units via the ribulose monophosphate pathway for formaldehyde fixation, and have a DNA base composition of 49 mol% guanine plus cytosine. The type strain, NCMB 2265, has been namedMethylomonas pelagica sp. nov. This upper ocean methanotroph may obtain its C1 substrates in situ from particles of algal debris that become anoxic, ferment, and accumulate in the thermocline to form a false benthos. 相似文献
999.
Barbara Vilhar Maja Ravnikar Milan Schara Marjana Nemec Nada Gogala 《Plant cell reports》1991,10(11):541-544
Summary Jasmonic acid (JA) and its derivatives are a novel group of plant endogenous growth regulators. In our experiments some new data about the physiological effects of JA were obtained using electron paramagnetic resonance spectroscopy. Experiments were performed on potato plants (Solanum tuberosum L. cv. Vesna) grown in vitro. Different quantities of JA (0.1–10 M) were added to the growth medium. Root samples of plants grown on media supplemented with JA showed a more rapid spin probe N-oxyl-2,2,6,6-tetramethyl piperidine reduction than the control plants, which is a possible indicator of altered root permeability. Samples of leaf protoplasts were probed with methyl ester of 5-doxyl-haxadecanoic acid. We observed a membrane fluidity decrease in protoplasts isolated from plants grown on higher concentrations of JA (1 and 10 M).Abbreviations JA
jasmonic acid
- Me-JA
methyl jasmonate
- EPR
electron paramagnetic resonance
- RubisCO
ribulose-1,5-biphosphate carboxylase/oxigenase
- MeFASL(10,3)
methyl ester of 5-doxyl-hexadecanoic acid
- MES
(2(N-morpholino)ethanesulfonic acid)
- TEMPO
N-oxyl-2,2,6,6-tetramethyl piperidine 相似文献
1000.
The complexation of Fe(III) with an Amadori compound derived from L-tyrosine was studied. The isolated complex was characterized by elemental analyses, Fourier transform infrared (FTIR) and 13C nuclear magnetic resonance (NMR) spectroscopy. Analyses indicate that the ligand is coordinated through the amino and carboxylate groups of the tyrosine part of the molecule. 相似文献