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51.
Bhag Singh Bohdan J. Soltys Zai-Chuan Wu Hasmukh V. Patel Karl B. Freeman Radhey S. Gupta 《Experimental cell research》1997,234(2):205
The cDNA for Chinese hamster mitochondrial Hsp70 (mHsp70) was cloned and sequenced using a polymerase chain reaction probe based on conserved regions in the Hsp70 family of proteins. The encoded protein consists of 679 amino acids which includes a N-terminal mitochondrial targeting sequence of 46 amino acids. The mHsp70 protein contains several sequence signatures that are characteristics of prokaryotic and eukaryotic organellar Hsp70 homologs. In a phylogenetic tree based on Hsp70 sequences, it branches with the gram-negative proteobacteria, supporting the endosymbiotic origin of mitochondria from this group of prokaryotes. The mHsp70 cDNA was transcribed and translatedin vitroand its import into isolated rat heart mitochondria was examined. The precursor mHsp70 was converted into a mature form of lower molecular mass (≈71 kDa) which became resistant to trypsin digestion. The import of mHsp70 into mitochondria was not observed in the presence of an uncoupler of energy metabolism or when the N-terminal presequence was lacking. The cDNA for mHsp70 was expressed inEscherichia coliand a polyclonal antibody to the purified recombinant protein was raised. The antibody shows no cross-reactivity to recombinant cytosolic Hsp70 protein and in 2-D gel blots it reacted specifically with the mHsp70 protein only. In immunofluorescence experiments, the antibody predominantly labeled mitochondria, and the observed labeling pattern was identical to that seen with a monoclonal antibody to the mitochondrial Hsp60 chaperonin. The affinity-purified antibody to mHsp70 was also employed to examine the subcellular distribution of the protein by cryoelectron microscopy and the immunogold-labeling technique. In these experiments, in addition to mitochondria, labeling with mitochondrial Hsp70 antibody was also observed on the plasma membrane and in unidentified cytoplasmic vesicles and granules. These studies raise the possibility that similar to the Hsp60 chaperonin and a number of other mitochondrial proteins, mHsp70 may have an extramitochondrial role. 相似文献
52.
Selfish long-term benefits of hoarding in the Siberian jay 总被引:3,自引:3,他引:0
We followed the consumption of cached food in Siberian jay flocksduring winter. Siberian jay flocks contain kin associationscomposed of parents in company with mature offspring. Further,flocks often contain immigrants not closely related to the groupmembers. We studied the extent to which Siberian jay offspringkept caches to themselves or whether they showed a kin biasand shared cached food mutualistically with relatives (parents/siblings)thus making an inclusive fitness gain. We recorded the retrievalof cached food using radio-ptilochronology, a technique thatdetects the consumption of a radioactively labeled food itemin the growth bar laid down in a growing feather the day ofconsumption. Food caching entailed a selfish benefit to thehoarder. The hoarding bird showed a substantial "recovery advantage"and retrieved its own cached food seven times as often as anyof its flock mates. There was no evidence for mutualistic sharingof caches among relatives. This selfish benefit persisted throughoutthe 7-week period for which we could follow the consumptionof labeled food. 相似文献
53.
Dr. Bohdan Křísa 《Plant Systematics and Evolution》1972,120(3):349-352
Zusammenfassung Aus dem zentralen Bhutan wird ein neues Taxon beschrieben:Pyrola chlorantha Sw. subsp.fallax
Kísa (SektionChlorantha
Kísa, SeriesChloranthae
Kísa). Die nächsten Fundorte der disjunktnordhemi-sphärisch verbreitetenP. chlorantha subsp.chlorantha liegen im mongolisch-sowjetischen Grenzgebiet (Baikal-Dahurien) 相似文献
54.
Je popsáno laboratorní gazometrické za?ízení pro stanovení intensity fotosynthesy v regulovaných podmínkách, umo?ňující difereněním zapojením infra?erveného analysátoru dosáhnout vysoké p?esnosti p?i stanovení rozdílu v koncentraci CO2 mezi kontrolnín vzduchem a vzduchem ochuzeným o asimilovaný CO2. Infra?ervený analysátor je zapojen tak, ?e jednou trubicí trvale prochází vzduch kontrolní a druhou “ochuzený” vzduch pokusný, tak?e výchylka registrujícího p?ístroje, kterou je mo?no zna?ně zesílit, odpovídá p?ímo absolutní hodnotě ochuzení, tedy p?i známém pr?toku p?ímo intensitě fotosynthesy. Tak je pr?měrná chyba stanovení intensity fotosynthesy vyjád?ena chybou stanovení koncentrace CO2 p?ístrojem p?i pou?itém zesílení v procentech diference a nikoliv v procentech několikánásobně vy??í absolutní koncentrace CO2, jak je tomu p?i absolutním zapojení. P?ípadné kolísání koncentrace CO2 v kontrolním vzduchu je registrováno druhým infra?erveným analysátorem, který je zapojen normálně, tj. absolutně. K exposici rostliny běhern pokusu je pou?íváno jednoduché klimatisované komory s regulovanou teplotou (±0,2° C) a vlhkostí (±2 a? 5% rel. vlhkosti) vzduchu s vysokou regulovancu stabilní intensitou osvětlení (a? do cca 3,2. 106 erg. cm?2. sec?1) a s mo?ností zvy?ovat koncentraci CO2 vevzduchu. 相似文献
55.
56.
The dielectric permittivity and conductivity of canine kidney tissue samples were measured at Rf frequencies between ?20 °C and +20 °C. Some of the kidneys had been perfused with DMSO (10%) in canine plasma, others with physiological saline alone. The DMSO greatly increases the conductivity of frozen tissue above that of tissue not treated with this cryoprotectant. Apparently, the chief reason for nonuniform heating of a partially frozen organ in a microwave field is the great change in tissue conductivity as it thaws. We suggest that the effect on the conductivity of tissue should be considered in the choice of a cryoprotectant for tissues which are to be thawed by microwave or radiofrequency irradiation. 相似文献
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59.
Hypoxanthine-guanine phosphoribosyl transferase (HGPRT; E.C. 2.4.2.8) has been studied in erythrocytes of patients with Lesch-Nyhan syndrome by polyacrylamide gel electrophoresis. The location of this enzyme in gel was determined by radiochemical assay. Inosine monophosphate (the reaction product of HGPRT with radioactive hypoxanthine and 5-phosphorylribose-1-pyrophosphate) was precipitated in the gel at the site of its formation with lanthanum chloride. The zone containing radioactive inosine monophosphate was located by continuous monitoring of mechanically fractionated gels in a scintillation spectrometer. The sensitivity of this method has permitted the detection of the very low HGPRT activity in the electropherograms of hemolysates of patients with Lesch-Nyhan syndrome. Among six patients, four had a mutant enzyme which migrated 15% faster than the normal; the other two had a mutant enzyme with about 12% faster migration. These mutants were designated HGPRT-LN and HGPRT-LN slow, respectively. These observations indicate that the mutant gene on the X chromosome codes for a protein of altered structure.Aided by U.S. Public Health Service grants Nos. HD 04608 and HD 03015 from the National Institute of Child Health and Human Development and GM 17702 from the National Institute of General Medical Sciences, National Institutes of Health.Presented in part at the 1971 meeting of the Western Society for Pediatric Research, Carmel, California. 相似文献
60.
Wojciech Ciesielski Bohdan Achremowicz Piotr Tomasik Malgorzata Baczkowicz Jaroslaw Korus 《Carbohydrate polymers》1997,34(4):577-308
Several varieties of flours were subjected to thermolysis up to 400 °C. The thermal characteristics of 13 flours were similar for all flours except soy. The weight loss of these flours up to 400 °C ranged from 65 to 97%. Although flours began to decompose at lower temperatures than did corresponding starches, there was less radical decomposition in flours than in starches as proved by Electron Paramagnetic Resonance absorption (EPR) spectra. The order of heat resistance to the radical decomposition for starches and flours paralleled one another, however, flours generated radicals at temperatures approximately 20 °C higher than in corresponding starches. The data showed that cereals did not form free radicals before carbonization and thus they could be safely processed in the temperature intervals generally used in baking, roasting, and frying. 相似文献