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91.
Mouse heart valve structure and function: echocardiographic and morphometric analyses from the fetus through the aged adult 总被引:1,自引:0,他引:1
Hinton RB Alfieri CM Witt SA Glascock BJ Khoury PR Benson DW Yutzey KE 《American journal of physiology. Heart and circulatory physiology》2008,294(6):H2480-H2488
The purpose of this study is to provide standard echocardiographic and morphometric data for normal mouse valve structure and function from late fetal to aged adult stages. Cross-sectional, two-dimensional and Doppler transthoracic echocardiography was performed in C57BL6 mice anesthetized with 1% to 2% isoflurane at embryonic day 18.5 (late fetal), 10 days (neonate), 1 mo (juvenile), 2 mo (young adult), 9 mo (old adult), and 16 mo (aged adult). Normal annulus dimensions indexed to age or weight, and selected flow velocities, were established by echocardiography. After echocardiographic imaging, hearts were harvested and histological and morphometric analyses were performed. Morphometric analysis demonstrated a progressive valve thinning and elongation during the fetal and juvenile stages that plateaued during adult stages (ANOVA, P < 0.01); however, there was increased thickening of the hinge of the aortic valve with advanced age, reminiscent of human aortic valve sclerosis. There was no age-related calcification. The results of this study provide comprehensive echocardiographic and morphometric data for normal mouse valve structure and function from late fetal to aged adult stages and should prove useful as a reference standard for future studies using mouse models of progressive valve disease. 相似文献
92.
Ruth H. Leeney Rachel Amies Annette C. Broderick Matthew J. Witt Jan Loveridge Joana Doyle Brendan J. Godley 《Biodiversity and Conservation》2008,17(10):2323-2338
Marine vertebrate strandings data can provide insights into the long-term dynamics of cetacean populations, and the threats
they face. We investigate whether the spatio-temporal patterns of cetacean strandings around Cornwall, SW Britain, have changed
in the past century. Analysis of strandings from 1911 to 2006 (n = 2,257) show that, since the mid-1970s, the relative frequency of strandings of common dolphins (Delphinus delphis), harbour porpoises (Phocoena phocoena) and pilot whales (Globicephala melas) has increased significantly. Seasonal peaks in strandings frequencies are apparent, between December and March for harbour
porpoises and common dolphins, and between November and January for pilot whales. There were significant positive trends in
the number of common dolphin and harbour porpoise strandings, as a proportion of total strandings, over time. Strandings of
common dolphins, porpoises and all other species occur more frequently on the south coast of Cornwall. A total of 415 cetaceans
were subject to full veterinary necropsy to determine cause of death, between 1990 and 2006, and 253 (61%) of these individuals
were determined to have died due to bycatch in fishing gear. Analyses of industrialised fishing pressure in UK waters show
the seas around Cornwall to be one of the most heavily fished areas of the UK. We suggest a number of factors that could be
responsible for the recent increases in cetacean strandings in southwest UK waters in recent years, including survey effort,
as well as abundance and range shifts that are potentially linked with climate change. Although detectable levels of bycatch
rate have not increased over time, fisheries interactions are in significant part responsible for mortality patterns and are
worthy of more detailed investigation.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
93.
The Madagascan endemic, Bryophyllum delagoense (Crassulaceae), is a major weed in Queensland, Australia. Despite having first been recorded in Australia in the 1940s, it is far more invasive there than on the African mainland where it was introduced more than 170 years ago. This may be due to a number of factors, one of which could be the occurrence of new natural enemy associations in southern Africa. Among the insects of crassulaceous plants that have extended their host ranges, a stem-boring weevil, Alcidodes sedi, was studied to elucidate its status as a natural enemy of B. delagoense in southern Africa and as a candidate biological control agent for introduction to Australia. Laboratory studies indicated that damage inflicted by adult and larval feeding caused significant reductions in stem length and number of leaves. Preliminary host-range trials revealed that A. sedi can complete its development on other species in the Crassulaceae, including most of the introduced Bryophyllum species and some Kalanchoe species native to South Africa. Despite the oligophagous nature of A. sedi and the fact that it can complete its development on a number of ornamental species in the Crassulaceae, it should be considered a potential biological control agent in Australia. All of the native Crassulaceae in Australia are in the genus Crassula, most of which are very small and therefore unlikely to support the development of a large weevil like A. sedi. However, additional host-range trials will have to be undertaken in Australia to determine whether the weevil can be considered safe for release. 相似文献
94.
DNAI2 mutations cause primary ciliary dyskinesia with defects in the outer dynein arm 总被引:1,自引:0,他引:1
95.
Witt AC Lakshminarasimhan M Remington BC Hasim S Pozharski E Wilson MA 《Biochemistry》2008,47(28):7430-7440
Human DJ-1, a disease-associated protein that protects cells from oxidative stress, contains an oxidation-sensitive cysteine (C106) that is essential for its cytoprotective activity. The origin of C106 reactivity is obscure, due in part to the absence of an experimentally determined p K a value for this residue. We have used atomic-resolution X-ray crystallography and UV spectroscopy to show that C106 has a depressed p K a of 5.4 +/- 0.1 and that the C106 thiolate accepts a hydrogen bond from a protonated glutamic acid side chain (E18). X-ray crystal structures and cysteine p K a analysis of several site-directed substitutions at residue 18 demonstrate that the protonated carboxylic acid side chain of E18 is required for the maximal stabilization of the C106 thiolate. A nearby arginine residue (R48) participates in a guanidinium stacking interaction with R28 from the other monomer in the DJ-1 dimer and elevates the p K a of C106 by binding an anion that electrostatically suppresses thiol ionization. Our results show that the ionizable residues (E18, R48, and R28) surrounding C106 affect its p K a in a way that is contrary to expectations based on the typical ionization behavior of glutamic acid and arginine. Lastly, a search of the Protein Data Bank (PDB) produces several candidate hydrogen-bonded aspartic/glutamic acid-cysteine interactions, which we propose are particularly common in the DJ-1 superfamily. 相似文献
96.
Interleukin-6 and alpha-2-macroglobulin indicate an acute-phase state in Alzheimer's disease cortices. 总被引:11,自引:0,他引:11
J Bauer S Strauss U Schreiter-Gasser U Ganter P Schlegel I Witt B Yolk M Berger 《FEBS letters》1991,285(1):111-114
Recent studies indicated that the formation of a major constituent of Alzheimer's disease (AD) senile plaques, called beta A4-peptide, does not result from normal processing of its precursor, amyloid precursor protein (APP). Since proteolytic cleavage of APP inside its beta A4 sequence was found to be part of APP processing the formation of the beta A4-peptide seems to be prevented under normal conditions. We considered whether in AD one of the endogenous proteinase inhibitors might interfere with APP processing. After we had recently found that cultured human neuronal cells synthesize the most potent of the known human proteinase inhibitors, alpha-2-macroglobulin (alpha 2M), upon stimulation with the inflammatory mediator interleukin-6 (IL-6) we now investigated whether alpha 2M and IL-6 could be detected in AD brains. Here we report that AD cortical senile plaques display strong alpha 2M and IL-6 immunoreactivity while no such immunoreactivity was found in age-matched control brains. Strong perinuclear alpha 2M immunoreactivity in hippocampal CA1 neurons of Alzheimer's disease brains indicates that neuronal cells are the site of alpha 2M synthesis in AD brains. We did not detect elevated IL-6 or alpha 2M levels in the cerebrospinal fluid of AD patients. Our data indicate that a sequence of immunological events which seem to be restricted to the local cortical environment is part of AD pathology. 相似文献
97.
98.
Structure of the mammalian kinetochore 总被引:27,自引:0,他引:27
The structure of the mammalian trilaminar kinetocnore was investigated using stereo electron microscopy of chromosomes in
hypotonie solutions which unraveled the chromosome but maintained microtubules. Mouse and Chinese hamster ovary cells were
arrested in Colcemid and allowed to reform microtubules after Colcemid was removed. Recovered cells were then swelled, lysed
or spread in hypotonic solutions which contained D2O to preserve microtubules. The chromosomes were observed in thin and thick sections and as whole mounts using high voltage
electron microscopy. Bundles of microtubules were seen directly attached to chromatin, indicating that the kinetochore outer
layer represents a differential arrangement of chromatin, continuous with the body of the chromosome. In cells fixed without
pretreatment, the outer layer could be seen to be composed of hairpin loops of chromatin stacked together to form a solid
layer. The hypotonically-induced unraveling of the outer layer was found to be reversible, and the typical 300 nm thick disk
reformed when cells were returned to isotonic solutions. Short microtubules, newly nucleated after Colcemid removal, were
found not to be attached to the kinetochore outer layer, but were situated in the fibrous corona on the external surface of
the outer layer. This was verified by observations of thick sections in stereo which made it possible to identify microtubule
ends within the section. Thus, kinetochore microtubules are nucleated within the fibrous corona, and subsequently become attached
to the outer layer.
We dedicate this paper to Wolfgang Beermann on the occasion of his 60th birthday in appreciation of many years of friendship
and his pioneering contributions in the field of chromosome biology 相似文献
99.
100.
Kahl Philip Podbiel Daniel Schneider Christian Makris Andreas Sindermann Simon Witt Christian Kilbane Deirdre Hoegen Michael Horn-von Aeschlimann Martin zu Heringdorf Frank Meyer 《Plasmonics (Norwell, Mass.)》2018,13(1):239-246
Plasmonics - Time-resolved imaging of the propagation and interference of isolated ultrashort surface plasmon polariton wave packets is demonstrated using two photon photoemission microscopy. The... 相似文献