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Query: UMLS:C0016382 (flushing)
 6,387 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated light acclimation in seedlings of the temperate oak Quercus petraea (Matt.) Liebl. and the co-occurring sub-Mediterranean oak Quercus pyrenaica Willd. Seedlings were raised in a greenhouse for 1 year in either 70 (HL) or 5.3% (LL) of ambient irradiance of full sunlight, and, in the following year, subsets of the LL-grown seedlings were transferred to HL either before leaf flushing (LL-HLBF plants) or after full leaf expansion (LL-HLAF plants). Gas exchange, chlorophyll a fluorescence, nitrogen fractions in photosynthetic components and leaf anatomy were examined in leaves of all seedlings 5 months after plants were moved from LL to HL. Differences between species in the acclimation of LL-grown plants to HL were minor. For LL-grown plants in HL, area-based photosynthetic capacity, maximum rate of carboxylation, maximum rate of electron transport and the effective photochemical quantum yield of photosystem II were comparable to those for plants grown solely in HL. A rapid change in nitrogen distribution among photosynthetic components was observed in LL-HLAF plants, which had the highest photosynthetic nitrogen-use efficiency. Increases in mesophyll thickness and dry mass per unit area governed leaf acclimation in LL-HLBF plants, which tended to have less nitrogen in photosynthetic components and a lower assimilation potential per unit of leaf mass or nitrogen than LL-HLAF plants. The data indicate that the phenological state of seedlings modified the acclimatory response of leaf attributes to increased irradiance. Morphological adaptation of leaves of LL-HLBF plants enhanced photosynthetic capacity per unit leaf area, but not per unit leaf dry mass, whereas substantial redistribution of nitrogen among photosynthetic components in leaves of LL-HLAF plants enhanced both mass- and area-based photosynthetic capacity.
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PMID:Leaf physiological versus morphological acclimation to high-light exposure at different stages of foliar development in oak. 1831 8

At the intra-plant level, temporal and spatial variations in plant defense traits can be influenced by resource requirements, defensive priorities and storage opportunities. Across a leaf age gradient, cyanogenic glycoside concentrations in the rainforest understory tree Ryparosa kurrangii B.L. Webber were higher in young expanding leaves than in mature leaves (2.58 and 1.38 mg g(-1), respectively). Moreover, cyanogens, as an effective chemical defense against generalist herbivores, contributed to a defense continuum protecting foliar tissue during leaf development. Chemical (cyanogens and phenolic compounds) and phenological (delayed greening) defense traits protected young leaves, whereas mature leaves were largely protected by physical defense mechanisms (lamina toughness; explained primarily by leaf mass per area). Cyanogen concentration was considerably higher in floral tissue than in foliar tissue and decreased in floral tissue during development. Across contrasting tropical seasons, foliar cyanogenic concentration varied significantly, being highest in the late wet season and lowest during the pre-wet season, the latter coinciding with fruiting and leaf flushing. Cyanogens in R. kurrangii appear to be differentially allocated in a way that maximizes plant fitness but may also act as a store of reduced nitrogen that is remobilized during flowering and leaf flushing.
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PMID:Intra-plant variation in cyanogenesis and the continuum of foliar plant defense traits in the rainforest tree Ryparosa kurrangii (Achariaceae). 1838 Dec 78

The aim of the present study was to assess genes expressed in maternal uterine tissue and pre-implantation embryos which are presumably involved in maternal recognition and establishment of canine pregnancy. For this purpose, 10 pregnant bitches were ovariohysterectomized between days 10 and 12 after mating. Four non-pregnant bitches served as controls. Early pregnancy was verified by flushing the uterine horns with PBS solution. The collected embryos (n = 60) were stored deep-frozen (-80 degrees C). Uterine tissue was excised, snaps frozen in liquid nitrogen and homogenized using TRI Reagent. All embryos from one litter were thawed together and also homogenized in TRI Reagent. RT-PCR was performed to prove mRNA expression of progesterone receptor, key enzymes of the prostaglandin synthesis pathway, selected growth factors, cytokines, immune cell receptors, major histocompatibility complex (MHC) and matrix-metalloproteinases (MMP). Only pregnant uteri revealed the presence of mRNA for interferon (IFN)-gamma, IL-4 and CD-8, which resembles the milieu in humans and other mammalians. Similarly, in day 10 embryos, mRNA for transforming growth factor-beta, insulin-like growth factor-1,-2, hepatocyte growth factor, leukaemia inhibitor factor, tumour necrosis factor-alpha, interleukin-1beta,-6,-8, cyclooxygenase-2, CD4(+) cells, and MMP-2 and -9 were detected, but not MHC-I or -II. We therefore suppose that the canine embryo, like its human counterpart, actively initiates measures to prevent attacks from the maternal immune system to prepare its own adhesion, nidation, growth and further development.
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PMID:Expression of genes in the canine pre-implantation uterus and embryo: implications for an active role of the embryo before and during invasion. 1839 90

Nutrient and hydrologic conditions strongly influence harmful planktonic and benthic cyanobacterial bloom (CHAB) dynamics in aquatic ecosystems ranging from streams and lakes to coastal ecosystems. Urbanization, agricultural and industrial development have led to increased nitrogen (N) and phosphorus (P) discharge, which affect CHAB potentials of receiving waters. The amounts, proportions and chemical composition of N and P sources can influence the composition, magnitude and duration of blooms. This, in turn, has ramifications for food web dynamics (toxic or inedible CHABs), nutrient and oxygen cycling and nutrient budgets. Some CHABs are capable of N2 fixation, a process that can influence N availability and budgets. Certain invasive N2 fixing taxa (e.g., Cylindrospermopsis, Lyngbya) also effectively compete for fixed N during spring, N-enriched runoff periods, while they use N2 fixation to supplant their N needs during N-deplete summer months. Control of these taxa is strongly dependent on P supply. However, additional factors, such as molar N:P supply ratios, organic matter availability, light attenuation, freshwater discharge, flushing rates (residence time) and water column stability play interactive roles in determining CHAB composition (i.e. N2 fixing vs. non-N2 fixing taxa) and biomass. Bloom potentials of nutrient-impacted waters are sensitive to water residence (or flushing) time, temperatures (preference for > 15 degrees C), vertical mixing and turbidity. These physical forcing features can control absolute growth rates of bloom taxa. Human activities may affect "bottom up" physical-chemical modulators either directly, by controlling hydrologic, nutrient, sediment and toxic discharges, or indirectly, by influencing climate. Control and management of cyanobacterial and other phytoplankton blooms invariably includes nutrient input constraints, most often focused on N and/or P. While single nutrient input constraints may be effective in some water bodies, dual N and P input reductions are usually required for effective long-term control and management of blooms. In some systems where hydrologic manipulations (i.e., plentiful water supplies) are possible, reducing the water residence time by flushing and artificial mixing (along with nutrient input constraints) can be effective alternatives. Blooms that are not readily consumed and transferred up the food web will form a relatively large proportion of sedimented organic matter. This, in turn, will exacerbate sediment oxygen demand, and enhance the potential for oxygen depletion and release of nutrients back to the water column. This scenario is particularly problematic in long-residence time (i.e., months) systems, where blooms may exert a strong positive feedback on future events. Implications of these scenarios and the confounding issues of climatic (hydrologic) variability, including droughts, tropical storms, hurricanes and floods, will be discussed in the context of developing effective CHAB control strategies along the freshwater-marine continuum.
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PMID:Nutrient and other environmental controls of harmful cyanobacterial blooms along the freshwater-marine continuum. 1846 71

The reaction of deoxyhemoglobin with nitrite was characterized in the presence of dithionite using hemoglobin in solution or bound to the cytoplasmic domain of band 3 (CDB3). Deoxyhemoglobin was generated by predeoxygenation (nitrogen flushing followed by addition of dithionite), or transiently, by rapidly mixing oxyhemoglobin with nitrite and dithionite simultaneously. Wavelength-dependent kinetic studies confirmed the formation of nitrosyl hemoglobin. Furthermore, the rate of reaction was independent of dithionite concentration, indicating that dithionite does not reduce nitrite to nitric oxide directly. Model simulation studies showed that superoxide anion generated by dithionite reduction of molecular oxygen was not a factor in the reaction kinetics. CDB3-bound hemoglobin reacted faster with nitrite than did hemoglobin in solution. This difference was most pronounced for predeoxygenated hemoglobin and least pronounced for rapidly deoxygenated hemoglobin. The smaller difference observed in the rapid deoxygenation experiment was associated with much faster kinetics compared to the predeoxygenation experiment. Model simulation studies showed, and literature evidence indicates, that faster kinetics in the rapid deoxygenation experiment were related to the initial presence of R-state Hb(II)O 2 alphabeta dimers, both in dilute solution and when bound to CDB3. Thus, rapidly deoxygenated CDB3-bound hemoglobin alphabeta dimers react 5-fold faster with nitrite than predeoxygenated tetrameric hemoglobin in solution. Faster nitrite reductase kinetics for CDB3-bound hemoglobin suggests the possibility of preferential nitric oxide generation at the inner surface of the erythrocyte membrane, thus coupling the release of oxygen from hemoglobin to the production and successful release of nitric oxide from the erythrocyte, and the regulation of blood flow.
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PMID:Kinetics of reaction of nitrite with deoxy hemoglobin after rapid deoxygenation or predeoxygenation by dithionite measured in solution and bound to the cytoplasmic domain of band 3 (SLC4A1). 1846 75

The factors regulating the eutrophication susceptibility of seven oligohaline regions in the sub-estuaries of Mobile Bay, Alabama were examined in a comparative analysis. The oligohaline regions differed primarily by the dominant land-use of their upstream watersheds, with two of the regions being primarily urban, two being primarily agricultural, and three being primarily forested. A stepwise model selection procedure was used to determine a suite of multiple regression models describing eutrophication response, in terms of a chlorophyll a (chla) on a sampling event basis, in relation to estuarine mixing time scales, nutrient concentrations, light availability, and watershed delivery of freshwater and nutrients. The models indicated a strong positive relationship between chla and mixing time scales (i.e., residence time or freshwater flushing time). Mixing time scales longer than five days allowed maximum chla (64 microg l(-1)), while lowest chla (< 1 microg l(-1)) occurred when mixing time scales were less than two days. Of the watershed inputs, chla exhibited opposing relationships with the components of freshwater load, having a negative relationship with discharge and a positive relationship with incoming freshwater nitrogen concentrations. Estuarine phosphorus concentrations and photosynthetically active radiation were also found to be good descriptors of chla. The comparative approach employed here allowed for the development of empirical models that were used to determine the nutrient concentration reductions required to achieve a trophic state of < 20 microg l(-1) chla. The average reductions in nitrogen and phosphorus needed to achieve this trophic state ranged from 0 to 32%.
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PMID:Regulation of eutrophication susceptibility in oligohaline regions of a northern Gulf of Mexico estuary, Mobile Bay, Alabama. 1857 61

This paper evaluated the performance and suitability of a resources and nutrients oriented decentralized greywater treatment system which uses a submerged spiral wound module. This greywater treatment system is aimed at treating and recovering the resources present in the wastewater. The study revealed that the UF membrane filtration system was able to maintain a permeate flux between 6 and 10 L/m2/h. TOC can be reduced from the influent value of 161 to 28.6 mg/L in the permeate, meaning an average elimination rate of 83.4%. In addition, soluble nutrients such as ammonia and phosphorus can pass through the UF membrane and remain in the permeate. The total nitrogen and total phosphorus in the permeate were 16.7 and 6.7 mg/L respectively. The permeate was low in turbidity (below 1 NTU) and free of suspended solids and E. coli and had an excellent physical appearance. The permeate can be used in gardening and agriculture for irrigation and soil fertilization or alternatively for toilet flushing after disinfection. The retentate generated in this system can be treated with blackwater and kitchen waste in an anaerobic digester at a later stage for producing biogas or compost.
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PMID:Resources and nutrients oriented greywater treatment for non-potable reuses. 1858 76

The objective of this study was to examine the effects of dietary n-3 polyunsaturated fatty acid (n-3 PUFA) supplementation on embryo yield and quality in heifers. Animals were individually offered barley straw and concentrate diets supplemented with either palmitic acid (C16:0; CON) or a partially rumen protected n-3 PUFA-enriched supplement. Following oestrous cycle synchronisation, superovulation was induced using FSH. Blood samples were collected for the measurement of fatty acids, metabolites, insulin and IGF-1. On day 7 post-insemination the number of ovulations was estimated and embryos recovered non-surgically and quality graded. At embryo recovery 50 ml of the uterine flushing was collected from each horn for fatty acid analysis. Grade 1 embryos were isolated, snap frozen in liquid nitrogen and stored at -80 degrees C. mRNA expression for six genes, LIF, BAX, Cx43 and E-CAD associated with embryo development, and PPAR-alpha and -delta, associated with lipid metabolism was analysed. The n-3 PUFA supplementation increased plasma n-3 PUFA concentration (P<0.05) and reduced n-6:n-3 PUFA ratio (P<0.05). Uterine concentration of the n-3 PUFA, eicosapentaenoic acid was increased (P<0.05) and the concentration of arachidonic acid decreased (P<0.05) following n-3 PUFA supplementation. While CON increased triglyceride concentrations, diet did not affect the other plasma metabolites, insulin or IGF-1 (P>0.05). Similarly, there was no effect of diet on superovulation rate, embryo recovery rate, embryo quality (P>0.05) or mRNA expression of the genes examined (P>0.05).
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PMID:Embryo yield and quality following dietary supplementation of beef heifers with n-3 polyunsaturated fatty acids (PUFA). 1869 27

Prolonged cold storage of raw milks favors the growth of psychrotrophs, which produce heat-resistant exoenzymes of considerable spoilage potential; the bacterial proteases and lipases affect raw milk quality; among them phospholipases (PLs) may target the milk fat globule. More importantly, bacterial PLs are key virulence factors for numerous species. Two studies examined the use of nitrogen (N(2)) gas and examined its effect on psychrotrophs, proteases and lipase producers when the milk was stored in closed vessels; however, the effect on PLs producers is unknown. Here we show that by considering an open system the PLs producers were sooner or later excluded in raw milk (whereas the PLs producers in the non-treated controls culminated at 10(8)CFU/ml), by effective gas treatments that bring oxygen (O(2)) levels in milk lower than 0.1ppm. No increase of the PLs producers among the anaerobes was noticed during the course of the experiments. In the experiments performed at 6.0 degrees C, the delay after which the PLs producers were no longer detectable seemed independent of the initial level of PLs producers in raw milk (lower than 10(3)CFU/ml). We anticipate that flushing pure N(2) gas in raw milk tanks, considered as open systems, along the cold chain of raw milk storage and transportation, may be an additional technique to control psychrotrophs, and may also constitute an interesting perspective for limiting their spoilage and pathogenic potential in food materials in general.
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PMID:Exclusion of phospholipases (PLs)-producing bacteria in raw milk flushed with nitrogen gas (N(2)). 1869

We describe a simple terahertz (THz) time domain spectrometer with a bandwidth extending up to 7.5 THz. We show that by keeping the generation and detection crystals close to each other a high signal-to-noise ratio (SNR) can be achieved without using lock-in detection and dry nitrogen flushing. The observed spectra show very good agreement with the spectra calculated based on a simple model which includes phase matching and absorption in the generation and detection crystals. Using this set-up we have measured the absorption lines in D-tartaric acid from 0.5 THz up to 7 THz. We show that the high frequency region > 3 THz is the better choice to measure small changes in the water content of a hygroscopic sample compared to the low frequency region.
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PMID:Quasi-near field terahertz generation and detection. 1871 19


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