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51.
Pericentric heterochromatin becomes enriched with H2A.Z during early mammalian development 下载免费PDF全文
Determining how chromatin is remodelled during early development, when totipotent cells begin to differentiate into specific cell types, is essential to understand how epigenetic states are established. An important mechanism by which chromatin can be remodelled is the replacement of major histones with specific histone variants. During early mammalian development H2A.Z plays an essential, but unknown, function(s). We show here that undifferentiated mouse cells of the inner cell mass lack H2A.Z, but upon differentiation H2A.Z expression is switched on. Strikingly, H2A.Z is first targeted to pericentric hetero chromatin and then to other regions of the nucleus, but is excluded from the inactive X chromosome and the nucleolus. This targeted incorporation of H2A.Z could provide a critical signal to distinguish constitutive from facultative heterochromatin. In support of this model, we demonstrate that H2A.Z can directly interact with the pericentric heterochromatin binding protein INCENP. We propose that H2A.Z functions to establish a specialized pericentric domain by assembling an architecturally distinct chromatin structure and by recruiting specific nuclear proteins. 相似文献
52.
Activities of Bacillus thuringiensis Insecticidal Crystal Proteins Cyt1Aa and Cyt2Aa against Three Species of Sheep Blowfly 下载免费PDF全文
Chris N. Chilcott Peter J. Wigley Andrew H. Broadwell Danny J. Park David J. Ellar 《Applied microbiology》1998,64(10):4060-4061
The toxicity of Bacillus thuringiensis Cyt1Aa protein to sheep blowfly larvae depends on its solubilization and proteolytic activation. Cyt1Aa crystals were not toxic. Full-length and trypsin-digested Cyt1Aa proteins were toxic to larvae of three species of sheep blowfly. Neither full-length nor trypsin-digested Cyt2A soluble crystal proteins were toxic. 相似文献
53.
54.
Nitric oxide (NO) is a critical biological mediator involved in numerous diseases. However, the short lifetime of this molecule in biological conditions can make its study in situ complicated. Here, we review some recent results on the role of NO in angiogenesis, obtained using a biocompatible microelectrode array. This simple system allowed for the quick and easy quantification of NO released from cells grown directly on the surface of the sensor. We have used this technology to demonstrate that angiogenin induces NO release, and to partially elucidate its intracellular transduction pathway. 相似文献
55.
56.
Laurel R. Yohe Paúl M. Velazco Danny Rojas Beth E. Gerstner Nancy B. Simmons Liliana M. Dávalos 《Biology letters》2015,11(11)
The earliest record of plant visiting in bats dates to the Middle Miocene of La Venta, the world''s most diverse tropical palaeocommunity. Palynephyllum antimaster is known from molars that indicate nectarivory. Skull length, an important indicator of key traits such as body size, bite force and trophic specialization, remains unknown. We developed Bayesian models to infer skull length based on dental measurements. These models account for variation within and between species, variation between clades, and phylogenetic error structure. Models relating skull length to trophic level for nectarivorous bats were then used to infer the diet of the fossil. The skull length estimate for Palynephyllum places it among the larger lonchophylline bats. The inferred diet suggests Palynephyllum fed on nectar and insects, similar to its living relatives. Omnivory has persisted since the mid-Miocene. This is the first study to corroborate with fossil data that highly specialized nectarivory in bats requires an omnivorous transition. 相似文献
57.
Qihong Zou Bin-Ke Yuan Hong Gu Dongqiang Liu Danny J. J. Wang Jia-Hong Gao Yihong Yang Yu-Feng Zang 《PloS one》2015,10(3)
Resting-state fMRI studies have increasingly focused on multi-contrast techniques, such as BOLD and ASL imaging. However, these techniques may reveal different aspects of brain activity (e.g., static vs. dynamic), and little is known about the similarity or disparity of these techniques in detecting resting-state brain activity. It is therefore important to assess the static and dynamic characteristics of these fMRI techniques to guide future applications. Here we acquired fMRI data while subjects were in eyes-closed (EC) and eyes-open (EO) states, using both ASL and BOLD techniques, at two research centers (NIDA and HNU). Static brain activity was calculated as voxel-wise mean cerebral blood flow (CBF) using ASL, i.e., CBF-mean, while dynamic activity was measured by the amplitude of low frequency fluctuations (ALFF) of BOLD, i.e., BOLD-ALFF, at both NIDA and HNU, and CBF, i.e., CBF-ALFF, at NIDA. We showed that mean CBF was lower under EC than EO in the primary visual cortex, while BOLD-ALFF was higher under EC in the primary somatosensory cortices extending to the primary auditory cortices and lower in the lateral occipital area. Interestingly, mean CBF and BOLD-ALFF results overlapped at the visual cortex to a very small degree. Importantly, these findings were largely replicated by the HNU dataset. State differences found by CBF-ALFF were located in the primary auditory cortices, which were generally a subset of BOLD-ALFF and showed no spatial overlap with CBF-mean. In conclusion, static brain activity measured by mean CBF and dynamic brain activity measured by BOLD- and CBF-ALFF may reflect different aspects of resting-state brain activity and a combination of ASL and BOLD may provide complementary information on the biophysical and physiological processes of the brain. 相似文献
58.
Alvaro Alonso Bing Yu Waqas T. Qureshi Morgan E. Grams Elizabeth Selvin Elsayed Z. Soliman Laura R. Loehr Lin Y. Chen Sunil K. Agarwal Danny Alexander Eric Boerwinkle 《PloS one》2015,10(11)
Background
Atrial fibrillation (AF) is a common arrhythmia. Application of metabolomic approaches, which may identify novel pathways and biomarkers of disease risk, to a longitudinal epidemiologic study of AF has been limited.Methods
We determined the prospective association of 118 serum metabolites identified through untargeted metabolomics profiling with the incidence of newly-diagnosed AF in 1919 African-American men and women from the Atherosclerosis Risk in Communities study without AF at baseline (1987–1989). Incident AF cases through 2011 were ascertained from study electrocardiograms, hospital discharge codes, and death certificates.Results
During a median follow-up of 22 years, we identified 183 incident AF cases. In Cox proportional hazards models adjusted for age, sex, smoking, body mass index, systolic blood pressure, use of antihypertensive medication, diabetes, prevalent heart failure, prevalent coronary heart disease, and kidney function, two conjugated bile acids (glycolithocholate sulfate and glycocholenate sulfate) were significantly associated with AF risk after correcting for multiple comparisons (p<0.0004). Multivariable-adjusted hazard ratios (95% confidence intervals) of AF were 1.22 (1.12–1.32) for glycolithocholate sulfate and 1.22 (1.10–1.35) for glycocholenate sulfate per 1-standard deviation higher levels. Associations were not appreciably different after additional adjustment for alcohol consumption or concentrations of circulating albumin and liver enzymes.Conclusion
We found an association of higher levels of two bile acids with an increased risk of AF, pointing to a potential novel pathway in AF pathogenesis. Replication of results in independent studies is warranted. 相似文献59.
Fache V Gaillard J Van Damme D Geelen D Neumann E Stoppin-Mellet V Vantard M 《The Plant cell》2010,22(11):3804-3815
The acentrosomal plant mitotic spindle is uniquely structured in that it lacks opposing centrosomes at its poles and is equipped with a connective preprophase band that regulates the spatial framework for spindle orientation and mobility. These features are supported by specialized microtubule-associated proteins and motors. Here, we show that Arabidopsis thaliana MAP65-4, a non-motor microtubule associated protein (MAP) that belongs to the evolutionarily conserved MAP65 family, specifically associates with the forming mitotic spindle during prophase and with the kinetochore fibers from prometaphase to the end of anaphase. In vitro, MAP65-4 induces microtubule (MT) bundling through the formation of cross-bridges between adjacent MTs both in polar and antipolar orientations. The association of MAP65-4 with an MT bundle is concomitant with its elongation. Furthermore, MAP65-4 modulates the MT dynamic instability parameters of individual MTs within a bundle, mainly by decreasing the frequency of catastrophes and increasing the frequency of rescue events, and thereby supports the progressive lengthening of MT bundles over time. These properties are in line with its role of initiating kinetochore fibers during prospindle formation. 相似文献
60.
A global approach to crop wild relative conservation: securing the gene pool for food and agriculture 总被引:1,自引:0,他引:1
Nigel Maxted Shelagh Kell Álvaro Toledo Ehsan Dulloo Vernon Heywood Toby Hodgkin Danny Hunter Luigi Guarino Andy Jarvis Brian Ford-Lloyd 《Kew Bulletin》2010,65(4):561-576
In light of the growing concern over the potentially devastating impacts on biodiversity and food security of climate change
and the massively growing world population, taking action to conserve crop wild relatives (CWR), is no longer an option —
it is a priority. Crop wild relatives are species closely related to crops, including their progenitors, many of which have
the potential to contribute beneficial traits to crops, such as pest or disease resistance, yield improvement or stability.
They are a critical component of plant genetic resources for food and agriculture (PGRFA), have already made major contributions
to crop production and are vital for future food security; their systematic conservation in ways that ensure their continuing
availability for use is therefore imperative. This is a complex, interdisciplinary, global issue that has been addressed by
various national and international initiatives. Drawing on the lessons learnt from these initiatives we can now propose a
global approach to CWR conservation, the key elements of which are: (1) estimating global CWR numbers, (2) assessment of the
global importance of CWR diversity, (3) current conservation status, (4) threats to CWR diversity, (5) systematic approaches
to CWR conservation, (6) CWR informatics, and (7) enhancing the use of CWR diversity. 相似文献