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Differences in specificity and catalytic efficiency between allozymes of esterase-4 from Drosophila mojavensis 总被引:1,自引:0,他引:1
A more than 10-fold difference in the specificity and catalytic efficiency
for 1-naphthyl esters was measured between two allozymes of esterase-4 from
Drosophila mojavensis. This difference is mainly caused by a difference in
the affinity for the 1-naphthyl esters. The amino acid compositions of the
allozymes are not significantly different, which means that the difference
in primary structure is small. Small differences in primary structure
generally do not result in such a large increase in catalytic efficiency
and such a large shift in substrate specificity as was found in the present
study.
相似文献
324.
SREE KANTHASWAMY JILLIAN NG MARIA CECILIA T. PENEDO THEA WARD DAVID GLENN SMITH JAMES C. HA 《American journal of primatology》2012,74(11):1017-1027
Pigtailed macaques (Macaca nemestrina) provide an important model for biomedical research on human disease and for studying the evolution of primate behavior. The genetic structure of captive populations of pigtailed macaques is not as well described as that of captive rhesus (M. mulatta) or cynomolgus (M. fascicularis) macaques. The Washington National Primate Research Center houses the largest captive colony of pigtailed macaques located in several different housing facilities. Based on genotypes of 18 microsatellite (short tandem repeat [STR]) loci, these pigtailed macaques are more genetically diverse than captive rhesus macaques and exhibit relatively low levels of inbreeding. Colony genetic management facilitates the maintenance of genetic variability without compromising production goals of a breeding facility. The periodic introduction of new founders from specific sources to separate housing facilities at different times influenced the colony's genetic structure over time and space markedly but did not alter its genetic diversity significantly. Changes in genetic structure over time were predominantly due to the inclusion of animals from the Yerkes National Primate Research Center in the original colony and after 2005. Strategies to equalize founder representation in the colony have maximized the representation of the founders’ genomes in the extant population. Were exchange of animals among the facilities increased, further differentiation could be avoided. The use of highly differentiated animals may confound interpretations of phenotypic differences due to the inflation of the genetic contribution to phenotypic variance of heritable traits. Am. J. Primatol. 74:1017‐1027, 2012. © 2012 Wiley Periodicals, Inc. 相似文献
325.
Voskamp KE; Noorman N; Mastebroek HA; Van Schoot NE; Den Otter CJ 《Chemical senses》1998,23(5):521-530
Spike trains from individual antennal olfactory cells of tsetse flies
(Glossina spp.) obtained during steady-state conditions (spontaneous as
well as during stimulation with 1-octen-3-ol) and dynamic stimulation with
repetitive pulses of 1-octen-3-ol were investigated by studying the spike
frequency and the temporal structure of the trains. In general, stimulation
changes the intensity of the spike activity but leaves the underlying
stochastic structure unaffected. This structure turns out to be a renewal
process. The only independently varying parameter in this process is the
mean interspike interval length, suggesting that olfactory cells of tsetse
flies may transmit information via a frequency coding. In spike records
with high firing rates, however, the stationary records had significant
negative first- order serial correlation coefficients and were non-renewal.
Some cells in this study were capable of precisely encoding the onset of
the odour pulses at frequencies up to at least 3 Hz. Cells with a rapid
return to pre-stimulus activity at the end of stimulation responded more
adequately to pulsed stimuli than cells with a long increased spike
frequency. While short-firing cells process information via a frequency
code, long-firing cells responded with two distinctive phases: a phasic,
non-renewal response and a tonic, renewal response which may function as a
memory of previous stimulations.
相似文献
326.
Summary The antibiotic ionophores Br-X-537A and A-23187 alter the ultrastructure of neurohaemal tissue on the transverse nerve of the stick insect, Carausius morosus. Br-X-537A induces dramatic changes in the ultrastructural appearance of all three types of neurosecretory fibres present in the neurohaemal tissue. The neurosecretory granules become more electron-lucent and the mitochondria become more electron-opaque. The bounding membrane of the granules is frequently ruptured. A-23187, on the other hand, has no effect on two of the three types of fibres, but does produce an increase in the number of exocytotic profiles in the third.The two ionophores therefore have different effects on the same tissue. The results are discussed in the light of previous work with the use of these ionophores.We wish to thank Mrs. J. Birch for assistance with the electron micrographs, and Roche Products Ltd. and Lilly Research Centre Ltd. for gifts of the ionophores Br-X-537A and A-23187. The work was supported by the Science Research Council 相似文献
327.
Harry Alexander Charles Wood Katjana Ehrlich Stephanos Yerolatsitis András Kufcsák Tom Michael Quinn Susan Fernandes Dominic Norberg Nia Caitlin Jenkins Vikki Young Irene Young Katie Hamilton Sohan Seth Ahsan Akram Robert Rodrick Thomson Keith Finlayson Kevin Dhaliwal James Morgan Stone 《Journal of biophotonics》2023,16(2):e202200141
We present an endoscopic probe that combines three distinct optical fibre technologies including: A high-resolution imaging fibre for optical endomicroscopy, a multimode fibre for time-resolved fluorescence spectroscopy, and a hollow-core fibre with multimode signal collection cores for Raman spectroscopy. The three fibers are all enclosed within a 1.2 mm diameter clinical grade catheter with a 1.4 mm end cap. To demonstrate the probe's flexibility we provide data acquired with it in loops of radii down to 2 cm. We then use the probe in an anatomically accurate model of adult human airways, showing that it can be navigated to any part of the distal lung using a commercial bronchoscope. Finally, we present data acquired from fresh ex vivo human lung tissue. Our experiments show that this minimally invasive probe can deliver real-time optical biopsies from within the distal lung - simultaneously acquiring co-located high-resolution endomicroscopy and biochemical spectra. 相似文献
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