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排序方式: 共有174条查询结果,搜索用时 15 毫秒
1.
Djordje Boskov Mirjana Jocic Ksenija Jovanovic Milos Ljubisavljevic Radmila Anastasijevic 《Biological cybernetics》1994,71(4):341-348
Spike discharges of skeletomotor neurons innervating triceps surae muscles elicited by white noise modulated transmembrane
current stimulation and muscle stretch were studied in decerebrated cats. The white noise modulated current intensity ranged
from 4.3 to 63.2 nA peak-to-peak, while muscle stretches ranged from 100 μm to 4.26 mm peak-to-peak. The neuronal responses
were studied by averaging the muscle length records centered at the skeletomotor action potentials (peri-spike average, PSA)
and by Wiener analysis. Skeletomotor spikes appeared after a sharp peak in PSA of the injected current, preceded by a longer-lasting
smaller wavelet of either depolarizing or hyperpolarizing direction. The PSA amplitude was not related to the injected current
amplitude nor showed any differences related to the motor unit type. The PSA amplitudes were virtually independent of the
stretching amplitude σ, after an initial increase with stretching amplitudes in the range of 15–40 μm (S.D.), or 100–270 μm
peak-to-peak.Analyses of cross-spectra indicated a small or absent increase in gain with frequency in response to injected
current, but about 20 dB/decade in the range 10–100 Hz in response to muscle stretch. The peaks of both Wiener kernels in
response to current injection appear to decrease with the amplitude of injected current, but this decrease was not statistically
significant. The narrow first-order kernels suggest that the transfer function between the current input and spike discharge
is lowpass with a wide passband, i.e. there is very little change in dynamics. The values of the second-order kernels appear
to be nonzero only along the main diagonal. This is characteristic of a simple Hammerstein type cascade, i.e. a zero memory
nonlinearity followed by a linear system. Small values of second-order kernels away from the origin and narrow first-order
kernels suggest that the linear cascade contributes very little to the overall dynamic response.In contrast to Wiener kernels
found in response to current injection, the Wiener kernels in response to stretch showed a decreasing trend with stretch amplitude.
The size of the second-order kernels decreased to a somewhat larger extent with input amplitude than that of the first-order
kernels, indicating an amplitude-dependent nonlinearity. Overall, the transformation between length and spike output was described
as an LNNL cascade with second-order nonlinearities.
Received: 1 April 1993/Accepted in revised form: 24 March 1994 相似文献
2.
Nonspecific binding of monoclonal anti-FLAG M2 antibody in Indian mustard (Brassica juncea) 总被引:1,自引:0,他引:1
Chimeric constructs with the hydrophilic octapeptide FLAG epitope (DYKDDDDK) have been widely used as multipurpose tags for
identification, detection, and purification of FLAG fusion proteins. Constructs consisting of C-terminal FLAG-tagged genomic
and cDNA clones of anArabidopsis phytochelatin synthase gene,AtPCS1, were used in developing transgenic lines of Indian mustard. Presence and expression ofAtPCS1 in transgenic lines were confirmed by using PCR and Northern blot analyses. However, immunoblot analysis revealed strong
nonspecific binding of a monoclonal anti-FLAG M2 antibody to an endogenous protein in both shoot and leaf tissues of wild-type
Indian mustard (85-kDa) that masked presence of the phytochelatin synthase (PCS) protein of interest (55-kDa). Further analysis
revealed absence of a nonspecific protein in root tissues of transgenic plants, thus allowing detection of the FLAG-tagged
PCS protein. 相似文献
3.
Distinct specificities of repressible acid phosphatase from yeast toward phosphoseryl and phosphotyrosyl phosphopeptides 总被引:1,自引:0,他引:1
A Donella-Deana K Lopandic S Barbaric L A Pinna 《Biochemical and biophysical research communications》1986,139(3):1202-1209
By using [32P]-labeled phosphoaminoacids it has been shown that, at mu molar range concentrations, Tyr-32P but neither Ser-32P nor Thr-32P can be significantly dephosphorylated by highly purified repressible acid phosphatase from Saccharomyces cerevisiae. The phosphopeptide Arg-Arg-Ala-Ser(32P)-Val-Ala however, reproducing the phosphorylation site of pyruvate kinase and previously phosphorylated by cAMP-dependent protein kinase, can be very readily dephosphorylated with favourable kinetic constants (Km 0.28 microM, Vmax = 62 units/micrograms) while its derivatives Ala-Ser(32P)-Val-Ala, Arg-Arg-Ala-Thr(32P)-Val-Ala, Arg-Arg-Pro-Ser(32P)-Pro-Ala as well as other peptides and protein substrates phosphorylated by either protein kinase-C or casein kinase-2 are either unaffected or very slowly dephosphorylated by the phosphatase. Conversely Tyr-32P containing angiotensin, poly (Glu, Tyr) 4:1 and the phosphopeptide Asp-Ala-Glu-Tyr(32P)-Ala-Ala-Arg-Arg-Arg-Gly are all dephosphorylated with kinetic constants comparable to those of free phosphotyrosine (Km 0.2-1 microM; Vmax = 4-10 units/micrograms). It is proposed that, while acid phosphatase exhibits a broad specificity toward phosphotyrosine and phosphotyrosyl polypeptides, it is highly selective toward phosphoseryl sites fulfilling definite structural requirements which are reminiscent of those determining phosphorylation by cAMP-dependent protein kinase. 相似文献
4.
Dane Bicanic Darko Dimitrovski Svjetlana Luterotti Ksenija Marković Charlotte van Twisk Josephus G. Buijnsters Otto Dóka 《Food biophysics》2010,5(1):24-33
The trans-lycopene content of fresh tomato homogenates was assessed by means of the laser photoacoustic spectroscopy, the laser optothermal
window, micro-Raman spectroscopy, and colorimetry; none of these methods require the extraction from the product matrix prior
to the analysis. The wet chemistry method (high-performance liquid chromatography) was used as the absolute quantitative method.
Analytical figures of merit for all methods were compared statistically; best linear correlation was achieved for the chromaticity
index a* and chroma C*. 相似文献
5.
6.
Vitale K Trbojević-Cepe M Smolej-Narancić N 《Human biology; an international record of research》2002,74(4):545-554
Apolipoprotein polymorphisms are emerging as suitable markers for the study of the formation of human populations. In contrast to the data available for apolipoprotein E, the data regarding apolipoprotein H (protein, apoH; gene, APOH) variations are only beginning to accumulate. By blood plasma isoelectric focusing and immunoblotting, we analyzed the distribution of apoH phenotypes in 397 individuals (192 males; 205 females) from seven villages of an autochthonous population of the eastern Adriatic island of Krk. APOH allele frequencies were: APOH*2 = 0.877, APOH*3 = 0.098, APOH*1 = 0.025, with the majority of the sample being homozygous. No significant differences between villages were observed. When these data were compared to those of other populations studied so far, a significant association between APOH allele frequencies and latitude was observed. We hypothesize that this association reflects differences in diet composition across different climatic zones. 相似文献
7.
The RuvABC resolvase is indispensable for recombinational repair in sbcB15 mutants of Escherichia coli
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Zahradka D Zahradka K Petranović M Dermić D Brcić-Kostić K 《Journal of bacteriology》2002,184(15):4141-4147
The RuvABC proteins of Escherichia coli play an important role in the processing of Holliday junctions during homologous recombination and recombinational repair. Mutations in the ruv genes have a moderate effect on recombination and repair in wild-type strains but confer pronounced recombination deficiency and extreme sensitivity to DNA-damaging agents in a recBC sbcBC background. Genetic analysis presented in this work revealed that the (Delta)ruvABC mutation causes an identical DNA repair defect in UV-irradiated recBC sbcBC, sbcBC, and sbcB strains, indicating that the sbcB mutation alone is responsible for the extreme UV sensitivity of recBC sbcBC ruv derivatives. In experiments with gamma irradiation and in conjugational crosses, however, sbcBC (Delta)ruvABC and sbcB (Delta)ruvABC mutants displayed higher recombination proficiency than the recBC sbcBC (Delta)ruvABC strain. The frequency of conjugational recombination observed with the sbcB (Delta)ruvABC strain was quite similar to that of the (Delta)ruvABC single mutant, indicating that the sbcB mutation does not increase the requirement for RuvABC in a recombinational process starting from preexisting DNA ends. The differences between the results obtained in three experimental systems used suggest that in UV-irradiated cells, the RuvABC complex might act in an early stage of recombinational repair. The results of this work are discussed in the context of recent recombination models which propose the participation of RuvABC proteins in the processing of Holliday junctions made from stalled replication forks. We suggest that the mutant SbcB protein stabilizes these junctions and makes their processing highly dependent on RuvABC resolvase. 相似文献
8.
Verónica Guajardo Simón Solís Boris Sagredo Felipe Gainza Carlos Mu?oz Ksenija Gasic Patricio Hinrichsen 《PloS one》2015,10(5)
Linkage maps are valuable tools in genetic and genomic studies. For sweet cherry, linkage maps have been constructed using mainly microsatellite markers (SSRs) and, recently, using single nucleotide polymorphism markers (SNPs) from a cherry 6K SNP array. Genotyping-by-sequencing (GBS), a new methodology based on high-throughput sequencing, holds great promise for identification of high number of SNPs and construction of high density linkage maps. In this study, GBS was used to identify SNPs from an intra-specific sweet cherry cross. A total of 8,476 high quality SNPs were selected for mapping. The physical position for each SNP was determined using the peach genome, Peach v1.0, as reference, and a homogeneous distribution of markers along the eight peach scaffolds was obtained. On average, 65.6% of the SNPs were present in genic regions and 49.8% were located in exonic regions. In addition to the SNPs, a group of SSRs was also used for construction of linkage maps. Parental and consensus high density maps were constructed by genotyping 166 siblings from a ‘Rainier’ x ‘Rivedel’ (Ra x Ri) cross. Using Ra x Ri population, 462, 489 and 985 markers were mapped into eight linkage groups in ‘Rainier’, ‘Rivedel’ and the Ra x Ri map, respectively, with 80% of mapped SNPs located in genic regions. Obtained maps spanned 549.5, 582.6 and 731.3 cM for ‘Rainier’, ‘Rivedel’ and consensus maps, respectively, with an average distance of 1.2 cM between adjacent markers for both ‘Rainier’ and ‘Rivedel’ maps and of 0.7 cM for Ra x Ri map. High synteny and co-linearity was observed between obtained maps and with Peach v1.0. These new high density linkage maps provide valuable information on the sweet cherry genome, and serve as the basis for identification of QTLs and genes relevant for the breeding of the species. 相似文献
9.
The aim of this work was to determine the criteria for heat loads associated with an increase in mortality in different climatic regions of Croatia. The relationship between heat stress and mortality was analysed for the period 1983–2008. The input series is excess mortality defined as the deviations of mortality from expected values determined by means of a Gaussian filter of 183 days. The assessment of the thermal environment was performed by means of physiologically equivalent temperature (PET). The curve depicting the relationship between mortality and temperature has a U shape, with increased mortality in both the cold and warm parts of the scale but more pronounced in the warm part. The threshold temperature for increased mortality was determined using a scatter plot and fitting data by means of moving average of mortality; the latter is defined as the temperature at which excess mortality becomes significant. The values are higher in the continental part of Croatia than at the coast due to the refreshing influence of the sea during the day. The same analysis on a monthly basis shows that at the beginning of the warm season increased mortality occurs at a lower temperature compared with later on in the summer, and the difference is up to 15 °C between August and April. The increase in mortality is highest during the first 3–5 days and after that it decreases and falls below the expected value. Long-lasting heat waves present an increased risk, but in very long heat waves the increase in mortality is reduced due to mortality displacement. 相似文献
10.
Jasnic N Korac A Velickovic K Golic I Djordjevic J Djurasevic S Djordjevic I Vujovic P Cvijic G 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2010,48(4):507-512
The increased ambient temperature affects the function of hypothalamic-pituitary-adrenal (HPA) axis. Since the correlation among vasopressin (VP), adrenocorticotropic hormone (ACTH) and corticosterone (CORT) responses to various stressors have been long recognized, the aim of this study was to reveal the aforementioned hormones production and morphology of the pituitary gland after exposure to acute heat. Rats were exposed to high ambient temperature (38 °C) for 20 or 60 minutes. The circulating hormones were determined by an ELISA test or chemiluminescence's method. The results obtained show the elevation in ACTH and CORT secretion depending on the duration of heat exposure. The VP concentration increased only after prolonged exposure to heat (60 min). The pituitary morphology was examined by routine and fluorescent immunohistochemistry as well as electron microscopy. Observed changes in the anterior and posterior pituitary well corresponded to circulating hormones, regarding the volume density of ACTH-immunopositive cells, percentage of ACTH immunopositive area v. total area and number of VP-immunopositive containing varicose fibers per total area. Acute heat exposure also induced changes in shapes of ACTH-immunopositive cells. Cells appeared stellate with numerous slender cytoplasmic processes and degranulated, which is the most obvious after 20 min. In addition, immunopositivity of endothelial and anterior pituitary cells for VP suggests its influence on ACTH secretion. 相似文献