Epigenetic dynamics of imprinted X inactivation during early mouse development   总被引：2，自引：0，他引：2  

Okamoto I  Otte AP  Allis CD  Reinberg D  Heard E 《Science (New York, N.Y.)》2004,303(5658):644-649

The initiation of X-chromosome inactivation is thought to be tightly correlated with early differentiation events during mouse development. Here, we show that although initially active, the paternal X chromosome undergoes imprinted inactivation from the cleavage stages, well before cellular differentiation. A reversal of the inactive state, with a loss of epigenetic marks such as histone modifications and polycomb proteins, subsequently occurs in cells of the inner cell mass (ICM), which give rise to the embryo-proper in which random X inactivation is known to occur. This reveals the remarkable plasticity of the X-inactivation process during preimplantation development and underlines the importance of the ICM in global reprogramming of epigenetic marks in the early embryo.  相似文献   

The influence of fermentation processes and cereal grains in wholegrain bread on reducing phytate content   总被引：1，自引：0，他引：1  

Oliver Buddrick  Oliver A.H. JonesHugh J. Cornell  Darryl M. Small 《Journal of Cereal Science》2014

Wholegrain bread is generally thought of as being more healthy than white bread due to it having a higher content of dietary fibre, vitamins (especially vitamin B and E) and many important minerals. However, wholegrain bread also contains high levels of phytate (myo-inositolhexakisphosphate, InsP-6) which may bind desirable nutrients, preventing their absorption in the gut and thereby reducing the nutritional value of the end product. In order to evaluate factors influencing phytate levels, the effects of fermentation and selected wholemeal flours from rye, oats and wheat were investigated. Phytate levels were assessed using a spectrophotometric assay based on the measurement of iron with 2,2′-bipyridine. Phytate decreased in freshly ground wholegrain flour dough during the fermentation process with time of fermentation being the most important factor. Fermentation temperature was found to make only a small difference to the process of phytate reduction. Since the potential benefits of wholemeal breads incorporating various grains (e.g. oats and rye) are increasingly evident, this research has important implications for human health.  相似文献   

Modelling stemflow production by juvenile lodgepole pine (<Emphasis Type="Italic">Pinus contorta</Emphasis> var. <Emphasis Type="Italic">latifolia</Emphasis>) trees     

Adam J. McKee  Darryl E. Carlyle-Moses 《林业研究》2017,28(3):565-576

Stemflow is a focused point source input of precipitation and nutrients at the base of a tree or plant and can have a significant impact on site hydrology. To date, no known studies have modelled stemflow production for juvenile lodgepole pine (Pinus contorta var. latifolia). Meteorological conditions, tree characteristics, and stemflow were sampled for two juvenile lodgepole pine stands over the course of the 2009 growing season. Step-wise multiple regression was used to assess which meteorological and tree architecture variables influenced stemflow production for each research plot. Once predictor variables were identified, models were produced for each stand and a generic model was produced that applied to both plots. A model employing precipitation depth and crown projection area successfully explained 71.3% of the variation in stemflow production from sampled trees. Stemflow was found to represent 1.8% of the study period rainfall and, although not a large component of the plot-scale canopy water balance, it is an order of magnitude greater than the fractioning of stemflow from mature lodgepole and lodgepole pine dominated forest. Additionally, stemflow funnelling ratios were found to average 22.2 and 24.3 from the two sample plots over the study period with a single tree, single event maximum of 111.7 recorded for a tree with a 3.3 cm bole diameter and a rain depth of 17.4 mm.  相似文献   

Distribution of Vehicular Lead in Roadside Soils of Major Roads of Brisbane,Australia   总被引：1，自引：0，他引：1  

Al-Chalabi  Abdul Sahib  Hawker  Darryl 《Water, air, and soil pollution》2000,118(3-4):299-310

Collections were made from three sites in the urbanarea of Brisbane, Australia. At each site, soilsamples were collected from transects parallel andperpendicular to the roadway, as well as a depthprofile. Total lead was determined by refluxing thesamples with concentrated nitric acid (1 h) andorganic lead by shaking with cold ammoniacal methanol(Flameless AAS). Both chloride and bromide anionswere obtained from an aqueous extract (HPLC). Resultsshowed that vehicular emissions were the major sourceof lead in the roadside soils of this study. At siteslocated in relatively enclosed areas of higheratmospheric stability, both lead and bromide contentsdecreased markedly with increasing distance from theroadway. However, in the absence of such atmosphericstability, the distribution of both lead and bromidecontents revealed different patterns which wasattributed mainly to the effect of meteorologicalfactors such as wind direction and speed. The depthprofile of roadside soils generally showed leadaccumulation within the uppermost 5 cm, whereaselevated concentrations of bromide were observed at greater depth.  相似文献   

Plasticity in the diel vertical movement of two pelagic predators (Prionace glauca and Alopias vulpinus) in the southeastern Indian Ocean          下载免费PDF全文

Matthew Heard  Paul J. Rogers  Barry D. Bruce  Nicolas E. Humphries  Charlie Huveneers 《Fisheries Oceanography》2018,27(3):199-211

Management and conservation of marine predator species relies on a fundamental knowledge of their movements and behaviour. Pop‐up satellite archival tags were used to investigate the vertical movement patterns of five blue sharks (Prionace glauca) and one thresher shark (Alopias vulpinus) within the southeastern Indian Ocean. Sections of similar depth distribution, identified using a split moving window analysis, were investigated in relation to the thermal structure of the water column and activity rates. Minimum horizontal displacement of between 66 and 5,187 km for blue sharks and 16 km for the thresher shark were recorded over 863 tracking days. Maximum depths ranged from 540 to 807 m for blue sharks and 144 m for the thresher shark. All sharks displayed plasticity in their depth distribution, with diel vertical movements and surface‐oriented movements the two most common patterns. Diel movement of prey is the most likely explanation for diel vertical movements of thresher and blue sharks. This study has improved our understanding of the vertical movement patterns of these pelagic predators and the relationship between their depth distribution, temperature, and activity.  相似文献