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排序方式: 共有1409条查询结果,搜索用时 31 毫秒
41.
MarcOlivier MartinGuay Michaël Belluau Benoit Ct Ira Tanya Handa Mark D. Jewell Rim Khlifa Alison D. Munson Maxime Rivest Joann K. Whalen David Rivest 《Ecology and evolution》2022,12(1)
- Soil C is the largest C pool in forest ecosystems that contributes to C sequestration and mitigates climate change. Tree diversity enhances forest productivity, so diversifying the tree species composition, notably in managed forests, could increase the quantity of organic matter being transferred to soils and alter other soil properties relevant to the C cycle.
- A ten‐year‐old tree diversity experiment was used to study the effects of tree identity and diversity (functional and taxonomic) on soils. Surface (0–10 cm) mineral soil was repeatedly measured for soil C concentration, C:N ratio, pH, moisture, and temperature in twenty‐four tree species mixtures and twelve corresponding monocultures (replicated in four blocks).
- Soil pH, moisture, and temperature responded to tree diversity and identity. Greater productivity in above‐ and below‐ground tree components did not increase soil C concentration. Soil pH increased and soil moisture decreased with functional diversity, more specifically, when species had different growth strategies and shade tolerances. Functional identity affected soil moisture and temperature, such that tree communities with more slow‐growing and shade‐tolerant species had greater soil moisture and temperature. Higher temperature was measured in communities with broadleaf‐deciduous species compared to communities with coniferous‐evergreen species.
- We conclude that long‐term soil C cycling in forest plantations will likely respond to changes in soil pH, moisture, and temperature that is mediated by tree species composition, since tree species affect these soil properties through their litter quality, water uptake, and physical control of soil microclimates.
42.
Maitotoxin and P2Z/P2X7 purinergic receptor stimulation activate a common cytolytic pore 总被引:5,自引:0,他引:5
Schilling William P.; Wasylyna Tanya; Dubyak George R.; Humphreys Benjamin D.; Sinkins William G. 《American journal of physiology. Cell physiology》1999,277(4):C766
The effects ofmaitotoxin (MTX) on plasmalemma permeability are similar to thosecaused by stimulation of P2Z/P2X7ionotropic receptors, suggesting that1) MTX directly activatesP2Z/P2X7 receptors or2) MTX andP2Z/P2X7 receptor stimulationactivate a common cytolytic pore. To distinguish between these twopossibilities, the effect of MTX was examined in1) THP-1 monocytic cells before andafter treatment with lipopolysaccharide and interferon-, a maneuverknown to upregulate P2Z/P2X7receptor, 2) wild-type HEK cells andHEK cells stably expressing theP2Z/P2X7 receptor, and3) BW5147.3 lymphoma cells, a cellline that expresses functional P2Z/P2X7 channels that are poorlylinked to pore formation. In control THP-1 monocytes, addition of MTXproduced a biphasic increase in the cytosolic freeCa2+ concentration([Ca2+]i);the initial increase reflects MTX-inducedCa2+ influx, whereas the secondphase correlates in time with the appearance of large pores and theuptake of ethidium. MTX produced comparable increases in[Ca2+]iand ethidium uptake in THP-1 monocytes overexpressing theP2Z/P2X7 receptor. In bothwild-type HEK and HEK cells stably expressing theP2Z/P2X7 receptor, MTX-inducedincreases in[Ca2+]iand ethidium uptake were virtually identical. The response of BW5147.3cells to concentrations of MTX that produced large increases in[Ca2+]ihad no effect on ethidium uptake. In both THP-1 and HEK cells, MTX- andBz-ATP-induced pores activate with similar kinetics and exhibit similarsize exclusion. Last, MTX-induced pore formation, but not channelactivation, is greatly attenuated by reducing the temperature to22°C, a characteristic shared by theP2Z/P2X7-induced pore. Together,the results demonstrate that, although MTX activates channels that aredistinct from those activated byP2Z/P2X7 receptor stimulation, thecytolytic/oncotic pores activated by MTX- and Bz-ATP are indistinguishable. 相似文献
43.
Accurate characterization of features of the melatonin production curve is important for research in chronobiology. Local polynomial regression is used to model the plasma melatonin concentration curve and obtain consistent and asymptotically normally distributed estimates of synthesis onset and offset times, duration, peak concentration, and area under the curve. A simple production-clearance model for melatonin kinetics provides the connection between plasma concentrations and the melatonin production curve. This model identifies onset and offset times with critical points of derivatives of the concentration curve. The method proposed has the advantage of flexibility and ease of implementation. Local polynomial regression can be shown to produce consistent estimates of the regression curve and parameters of interest. Furthermore, the method can be implemented in any software package with weighted least squares routines. 相似文献
44.
Schwarzenbacher R von Delft F Jaroszewski L Abdubek P Ambing E Biorac T Brinen LS Canaves JM Cambell J Chiu HJ Dai X Deacon AM DiDonato M Elsliger MA Eshagi S Floyd R Godzik A Grittini C Grzechnik SK Hampton E Karlak C Klock HE Koesema E Kovarik JS Kreusch A Kuhn P Lesley SA Levin I McMullan D McPhillips TM Miller MD Morse A Moy K Ouyang J Page R Quijano K Robb A Spraggon G Stevens RC van den Bedem H Velasquez J Vincent J Wang X West B Wolf G Xu Q Hodgson KO Wooley J Wilson IA 《Proteins》2004,56(2):392-395
45.
Salt cress. A halophyte and cryophyte Arabidopsis relative model system and its applicability to molecular genetic analyses of growth and development of extremophiles 总被引:16,自引:0,他引:16
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46.
Comparative genomics identifies a flagellar and basal body proteome that includes the BBS5 human disease gene 总被引:31,自引:0,他引:31
Li JB Gerdes JM Haycraft CJ Fan Y Teslovich TM May-Simera H Li H Blacque OE Li L Leitch CC Lewis RA Green JS Parfrey PS Leroux MR Davidson WS Beales PL Guay-Woodford LM Yoder BK Stormo GD Katsanis N Dutcher SK 《Cell》2004,117(4):541-552
Cilia and flagella are microtubule-based structures nucleated by modified centrioles termed basal bodies. These biochemically complex organelles have more than 250 and 150 polypeptides, respectively. To identify the proteins involved in ciliary and basal body biogenesis and function, we undertook a comparative genomics approach that subtracted the nonflagellated proteome of Arabidopsis from the shared proteome of the ciliated/flagellated organisms Chlamydomonas and human. We identified 688 genes that are present exclusively in organisms with flagella and basal bodies and validated these data through a series of in silico, in vitro, and in vivo studies. We then applied this resource to the study of human ciliation disorders and have identified BBS5, a novel gene for Bardet-Biedl syndrome. We show that this novel protein localizes to basal bodies in mouse and C. elegans, is under the regulatory control of daf-19, and is necessary for the generation of both cilia and flagella. 相似文献
47.
Trinucleotide repeats (TNRs) are sequences whose expansion causes several genetic diseases and chromosome breakage. We report a novel finding that expanded CAG repeats activate the DNA damage response. Mutations in yeast MEC1, RAD9, or RAD53 genes result in increased rates of fragility of a CAG repeat tract while single or double deletions of RAD17 or RAD24 have only a modest effect on TNR fragility, indicating that signaling down the Rad9 pathway and not the Rad17-Rad24 pathway plays a major role in sensing and repairing CAG-tract breaks. Deletion of CHK1 had no effect on CAG fragility, suggesting that a Chk1-mediated G2 arrest is not required for TNR repair. Absence of Mec1, Ddc2, Rad17, Rad24, or Rad53 also gives rise to increased frequency of CAG repeat contractions, indicating that components of the checkpoint machinery play an active role in the maintenance of both chromosomal integrity and repeat stability at expanded CAG sequences. 相似文献
48.
Butler SP O'Sickey TK Lord ST Lubon H Gwazdauskas FC Velander WH 《Transgenic research》2004,13(5):437-450
Transgenic animals secreting individual chains and assembled fibrinogen were produced to evaluate the capacity of the mammary gland for maximizing assembly, glycosylation and secretion of recombinant human fibrinogen (rhfib). Transgenes were constructed from the 4.1kbp murine Whey Acidic Protein promoter (mWAP) and the three cDNAs coding for the A, B and fibrinogen chains. Transgenic mice secreted fully assembled fibrinogen into milk at concentrations between 10 and 200 g/ml, with total secretion of subunits approaching 700 g/ml in milk. Partially purified fibrinogen was shown to form a visible and stable clot after treatment with human thrombin and factor XIII. The level of assembled fibrinogen was proportional to the lowest amount of subunit produced where both the B and chains were rate limiting. Both the B and chains were glycosylated when co-expressed and the degree of saccharide maturation was dependent on expression level, with processing preferred for chains over B chains. Also, the subunit complexes 2, A2 and the individual subunits A, B and were found as secretion products. When the B was secreted individually, the glycosylation profile of the molecule was of a mature complex saccharide indicating recognition of the molecule by the glycosylation pathway without association with other fibrinogen chains. To date secretion of B chain has been not observed in any cell type, suggesting that the secretion pathway in mammary epithelia is less restrictive than that occurring in hepatocytes and other cells previously used to study fibrinogen assembly. 相似文献
49.
El-Sayed NM Ghedin E Song J MacLeod A Bringaud F Larkin C Wanless D Peterson J Hou L Taylor S Tweedie A Biteau N Khalak HG Lin X Mason T Hannick L Caler E Blandin G Bartholomeu D Simpson AJ Kaul S Zhao H Pai G Van Aken S Utterback T Haas B Koo HL Umayam L Suh B Gerrard C Leech V Qi R Zhou S Schwartz D Feldblyum T Salzberg S Tait A Turner CM Ullu E White O Melville S Adams MD Fraser CM Donelson JE 《Nucleic acids research》2003,31(16):4856-4863
50.
Platt FM Jeyakumar M Andersson U Heare T Dwek RA Butters TD 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2003,358(1433):947-954
Substrate reduction therapy uses small molecules to slow the rate of glycolipid biosynthesis. One of these drugs, N-butyldeoxynojirimycin (NB-DNJ), shows efficacy in mouse models of Tay-Sachs, Sandhoff and Fabry diseases. This offers the prospect that NB-DNJ may be of therapeutic benefit, at least in the juvenile and adult onset variants of these disorders. The infantile onset variants will require an additional enzyme-augmenting modality if the pathology is to be significantly improved. A second drug, N-butyldeoxyglactonojirimycin, looks very promising for treating storage diseases with neurological involvement as high systemic dosing is achievable without any side-effects. 相似文献