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1.
Aaron Mendez-Bermudez Alberto Hidalgo-Bravo Victoria E. Cotton Athanasia Gravani Jennie N. Jeyapalan Nicola J. Royle 《Nucleic acids research》2012,40(21):10809-10820
Approximately 10% of all cancers, but a higher proportion of sarcomas, use the recombination-based alternative lengthening of telomeres (ALT) to maintain telomeres. Two RecQ helicase genes, BLM and WRN, play important roles in homologous recombination repair and they have been implicated in telomeric recombination activity, but their precise roles in ALT are unclear. Using analysis of sequence variation present in human telomeres, we found that a WRN– ALT+ cell line lacks the class of complex telomere mutations attributed to inter-telomeric recombination in other ALT+ cell lines. This suggests that WRN facilitates inter-telomeric recombination when there are sequence differences between the donor and recipient molecules or that sister-telomere interactions are suppressed in the presence of WRN and this promotes inter-telomeric recombination. Depleting BLM in the WRN– ALT+ cell line increased the mutation frequency at telomeres and at the MS32 minisatellite, which is a marker of ALT. The absence of complex telomere mutations persisted in BLM-depleted clones, and there was a clear increase in sequence homogenization across the telomere and MS32 repeat arrays. These data indicate that BLM suppresses unequal sister chromatid interactions that result in excessive homogenization at MS32 and at telomeres in ALT+ cells. 相似文献
2.
L Berglund 《Biochimica et biophysica acta》1978,524(1):68-77
Pyruvate kinase (ATP:pyruvate 2-O-phosphotransferase, EC 2.7.1.40) type L was partly purified from rat kidney. During the last two purification steps, the incorporation of [32P]phosphate into protein on incubation with [32P]ATP and cyclic 3',5'-AMP-dependent protein kinase was found to parallel the pyruvate kinase activity. After phosphorylation of the enzyme, a major radioactive band with a molecular weight of 57 000 was found on polyacrylamide gel electrophoresis [32P]Phosphorylserine was isolated from the kidney pyruvate kinase. Immunological identity was found between the liver and kidney pyruvate kinases type L. By autoradiography of high-voltage electropherograms after partial acid hydrolysis of the phosphorylated rat liver and kidney pyruvate kinases type L, identical results were obtained. The affinity for phosphoenolpyruvate was found to be decreased by phosphorylation of the enzyme with a change in the apparent Km from 0.15 mM to 0.35 mM. After incubation of the phosphorylated kidney pyruvate kinase with phosphatase the phosphoenolpyruvate saturation curve was found to be identical to that for the unphosphorylated enzyme. Thus, the activity of the rat kidney pyruvate kinase type L is with all probability regulated by a reversible phosphorylation-dephosphorylation reaction, thereby indicating that hormonal regulation of gluconeogenesis via cyclic AMP may be of importance in the renal cortex. 相似文献
3.
Susanne Berglund Bryan J. Egner Henrik Gradén Joakim Gradén David G.A. Morgan Tord Inghardt Fabrizio Giordanetto 《Bioorganic & medicinal chemistry letters》2009,19(15):4268-4273
Herein, we disclose the discovery and optimization of 2-piperidin-4-yl-acetamide derivatives as MCH-R1 antagonists. Structural investigation of piperidin-4-yl-amide and piperidin-4-yl-ureas identified 2-piperidin-4-yl-acetamide-based MCH-R1 antagonists with outstanding in vivo efficacy but flawed with high affinity towards the hERG potassium channel. While existing hERG SAR information was employed to discover highly potent MCH-R1 antagonists with minimized hERG inhibition, additional hurdles prevented their subsequent clinical exploration. 相似文献
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5.
Apolipoprotein E has key functions in lipoprotein metabolism, and polymorphisms in the apolipoprotein E gene are associated with distinct lipoprotein patterns. The possibility of gene-nutrient interactions for apolipoprotein E has been addressed in many studies. Although results have generally been mixed, the indications for such an interaction have been more common in studies employing a metabolic challenge. Studies directly designed to examine apolipoprotein E gene-nutrient interactions are needed. 相似文献
6.
Dr. Lois Aldwin Robert Toso Robert Goodson Jennie Hunter 《Journal of industrial microbiology & biotechnology》1990,5(4):239-246
Summary The production of streptavidin byStreptomyces avidinii in several different media was examined at 24, 48 and 72 hours. Flask studies indicated that fermentation media containing either complex or multiple carbon sources resulted in higher yields of streptavidin than media with a single carbon source. Streptavidin could be detected in crude fermentation broths by use of a tritiated biotin binding assay. This assay appears to give useful estimates of streptavidin production. Depending upon the medium employed, streptavidin yields ranged from 0.5 mg/l to 53 mg/l. Production was successfully scaled up to ten liter fermentors. Streptavidin was purified in a one step process from centrifuged, concentrated fermentation broths by binding the protein to an iminobiotin column at pH 11 followed by elution at pH 4.0. Recovery percentages varied depending upon the solubility of the fermentation media ingredients. 相似文献
7.
Anders Berglund Angelo Bisazza rea Pilastro 《Biological journal of the Linnean Society. Linnean Society of London》1996,58(4):385-399
Secondary sexual characters in many species function both in male-male competition and as cues for female choice. Based on a literature compilation of existing knowledge of traits with this dual function, we propose that they commonly arise through intersexual selection processes and serve as honest signals to other males regarding fighting ability or dominance. Faking these traits, here called armaments, (i.e. weapons and status badges) is difficult, as they are constantly put to trial in male-male contests. Females that subsequently utilize them as indicators of male phenotypic quality when selecting a partner will benefit by acquiring males of higher quality to father their offspring. Thus, evolution of armaments through male-male competition is seen as a usually initiating process, whereas female choice later may assume a role as an additional selective factor. The reverse, that males use information from traits evolved through female choice, is, however, also possible. The traditional view of independently evolved and temporarily unordered intra- and intersexual selection processes fails to explain dual trait functions. Moreover, our model may more satisfyingly than traditional ones explain how trait honesty and trait genetic variance are maintained: theoretical and empirical evidence suggests that such honesty and variation are more easily maintained under male-male competition than under female choice. 相似文献
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9.
The operational sex ratio influences choosiness in a pipefish 总被引:3,自引:2,他引:1
If more females than males are available for mating in the breedingpopulation (i.e., the operational sex ratio, OSR, is femalebiased), males can afford to be choosy. In the pipefish (Syngnathustyphle) females compete for males, who are choosy. In natureOSRs are typically female biased, but may occasionally be malebiased. In a series of experiments, males were allowed to choosebetween a large and a small female under a perceived excessof either males or females. Under female bias, males preferredthe large female: they spent more time close to her than tothe small female; they courted the large female sooner thanthe small; and they tended to copulate sooner and more oftenwith the large female. Under male bias all these differencesvanished and males mated at random with respect to female size.Males reproduced at a faster rate under male than under femalebias because they received more eggs in their brood pouches.Thus, males switched from maximizing mate quality (i.e., beingchoosy) to minimizing the risk of not reproducing (i.e., beingquick) as the OSR became male biased. 相似文献
10.
Ewa Lindstrum Per Lindstrum Andr Berglund Kiell Hansson Mild Erik Lundgren 《Journal of cellular physiology》1993,156(2):395-398
Applied weak magnetic fields have been shown to affect cellular activity on several levels, but the mechanisms involved remain elusive. We have decided to study an early signal transduction event in the human T cell line Jurkat; oscillations of free [Ca2+]i, of the type seen by crosslinking the CD3 complex. Cells were exposed to a 50 Hz, 0.1 mT, sinusoidal magnetic field while intracellular free calcium was measured in individual cells, using fura-2 as a probe. An acute response was observed with oscillatory increases in [Ca2+]i, which subsided when the field was turned off. The effect of the magnetic field on [Ca2+]i was comparable to that achieved by an anti-CD3 monoclonal antibody. © 1993 Wiley-Liss, Inc. 相似文献