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1.
Leaching losses of nitrogen from a clay soil under grass and cereal crops in Finland 总被引:1,自引:0,他引:1
Antti Jaakkola 《Plant and Soil》1984,76(1-3):59-66
Summary A 16-plot experimental field was established in 1975 on a clay soil in Jokioinen, Finland. The water discharge through tile drains was measured and its ammonium and nitrate N contents determined for each plot separately. The surface runoff was also measured and analysed. The annual runoff and the N leached from the surface of moderately fertilized (100 kg/ha/y N) cereal plots varied during 1976–1982 from 21 to 301 mm and from 2 to 7 kg/ha, respectively. The discharge of water and leaching of N through subdrains varied from 65 to 225 mm and from 1 to 38 kg/ha, respectively. The highest leaching was probably caused by a previous fallow. The annual N uptake by the crop varied between 41 and 122 kg/ha.Of the fertilizer-N used for cereals, 20% of that applied in the autumn was lost, but only 1 to 4 per cent was lost when applied in the spring. There was much less N leaching from ley than from barley plots, although the former was given twice as much N. The rate of N fertilization had only a very slight effect on N leaching from both ley and barley plots.The results were compared with those obtained in lysimeters filled with clay, silt, sand and peat soils. No definite conclusions can be drawn because the lysimeter experimental data are only for the first year. 相似文献
2.
Lior Almagor Orna Chomsky-Hecht Adva Ben-Mocha Doran Hendin-Barak Nathan Dascal Joel A. Hirsch 《Channels (Austin, Tex.)》2012,6(6):468-472
CaV channels are multi-subunit protein complexes that enable inward cellular Ca2+ currents in response to membrane depolarization. We recently described structure-function studies of the intracellular α1 subunit domain I-II linker, directly downstream of domain IS6. The results show the extent of the linker’s helical structure to be subfamily dependent, as dictated by highly conserved primary sequence differences. Moreover, the difference in structure confers different biophysical properties, particularly the extent and kinetics of voltage and calcium-dependent inactivation. Timothy syndrome is a human genetic disorder due to mutations in the CaV1.2 gene. Here, we explored whether perturbation of the I-II linker helical structure might provide a mechanistic explanation for a Timothy syndrome mutant’s (human CaV1.2 G406R equivalent) biophysical effects on inactivation and activation. The results are equivocal, suggesting that a full mechanistic explanation for this Timothy syndrome mutation requires further investigation. 相似文献
3.
Tang ZZ Sharma S Zheng S Chawla G Nikolic J Black DL 《The Journal of biological chemistry》2011,286(12):10007-10016
CaV1.2 calcium channels play roles in diverse cellular processes such as gene regulation, muscle contraction, and membrane excitation and are diversified in their activity through extensive alternative splicing of the CaV1.2 mRNA. The mutually exclusive exons 8a and 8 encode alternate forms of transmembrane segment 6 (IS6) in channel domain 1. The human genetic disorder Timothy syndrome is caused by mutations in either of these two CaV1.2 exons, resulting in disrupted Ca(2+) homeostasis and severe pleiotropic disease phenotypes. The tissue-specific pattern of exon 8/8a splicing leads to differences in symptoms between patients with exon 8 or 8a mutations. Elucidating the mechanisms controlling the exon 8/8a splicing choice will be important in understanding the spectrum of defects associated with the disease. We found that the polypyrimidine tract-binding protein (PTB) mediates a switch from exon 8 to 8a splicing. PTB and its neuronal homolog, nPTB, are widely studied splicing regulators controlling large sets of alternative exons. During neuronal development, PTB expression is down-regulated with a concurrent increase in nPTB expression. Exon 8a is largely repressed in embryonic mouse brain but is progressively induced during neuronal differentiation as PTB is depleted. This splicing repression is mediated by the direct binding of PTB to sequence elements upstream of exon 8a. The nPTB protein is a weaker repressor of exon 8a, resulting in a shift in exon choice when nPTB replaces PTB in cells. These results provide mechanistic understanding of how these two exons, important for human disease, are controlled. 相似文献
4.
5.
Comprehensive analysis of two Shank3 and the Cacna1c mouse models of autism spectrum disorder
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P.A. Kabitzke D. Brunner D. He P.A. Fazio K. Cox J. Sutphen L. Thiede E. Sabath T. Hanania V. Alexandrov R. Rasmusson W. Spooren A. Ghosh P. Feliciano B. Biemans M. Benedetti A.L. Clayton 《Genes, Brain & Behavior》2018,17(1):4-22
To expand, analyze and extend published behavioral phenotypes relevant to autism spectrum disorder (ASD), we present a study of three ASD genetic mouse models: Feng's Shank3tm2Gfng model, hereafter Shank3/F, Jiang's Shank3tm1Yhj model, hereafter Shank3/J and the Cacna1c deletion model. The Shank3 models mimick gene mutations associated with Phelan–McDermid Syndrome and the Cacna1c model recapitulates the deletion underlying Timothy syndrome. This study utilizes both standard and novel behavioral tests with the same methodology used in our previously published companion report on the Cntnap2 null and 16p11.2 deletion models. We found that some but not all behaviors replicated published findings and those that did replicate, such as social behavior and overgrooming in Shank3 models, tended to be milder than reported elsewhere. The Shank3/F model, and to a much lesser extent, the Shank3/J and Cacna1c models, showed hypoactivity and a general anxiety‐like behavior triggered by external stimuli which pervaded social interactions. We did not detect deficits in a cognitive procedural learning test nor did we observe perseverative behavior in these models. We did, however, find differences in exploratory patterns of Cacna1c mutant mice suggestive of a behavioral effect in a social setting. In addition, only Shank3/F showed differences in sensory‐gating. Both positive and negative results from this study will be useful in identifying the most robust and replicable behavioral signatures within and across mouse models of autism. Understanding these phenotypes may shed light of which features to study when screening compounds for potential therapeutic interventions. 相似文献
6.
Species variation in the fixation and transfer of nitrogen from legumes to associated grasses 总被引:6,自引:0,他引:6
Summary Three legume species (alfalfa, red clover, and birdsfoot trefoil) in combination with five grass species (timothy, bromegrass,
red fescue, tall fescue, and orchardgrass) were used to study N transfer in mixtures, using the 15N dilution technique. The advantage of grass-legume mixtures was apparent. Total herbage and protein yields of grasses in mixtures
were higher than those alone, especially at the later cuts. This benefit of mixed cropping is mainly due to N transfer from
legumes to associated grasses. N2-fixation and N transfer by alfalfa rated highest, red clover intermediate, and birdsfoot trefoil lowest. The importance of
each pathway of N transfer from legumes appeared to differ between species. Alfalfa and red clover excreted more N than trefoil,
while the latter contributed more N from decomposition of dead nodule and root tissue. The greatest advantage from a grass-legume
mixture, with respect to the utilization of N released from the legume, varied with early maturing tall fescue (Kentucky 31),
orchardgrass (Juno), and bromegrass (Tempo), to intermediate timothy (Climax), and least with late maturing red fescue (Carlawn).
Contribution no. 817 of the Ottawa Research Station. 相似文献
7.
Depil K Beyl S Stary-Weinzinger A Hohaus A Timin E Hering S 《The Journal of biological chemistry》2011,286(36):31557-31564
The Timothy syndrome mutations G402S and G406R abolish inactivation of Ca(V)1.2 and cause multiorgan dysfunction and lethal arrhythmias. To gain insights into the consequences of the G402S mutation on structure and function of the channel, we systematically mutated the corresponding Gly-432 of the rabbit channel and applied homology modeling. All mutations of Gly-432 (G432A/M/N/V/W) diminished channel inactivation. Homology modeling revealed that Gly-432 forms part of a highly conserved structure motif (G/A/G/A) of small residues in homologous positions of all four domains (Gly-432 (IS6), Ala-780 (IIS6), Gly-1193 (IIIS6), Ala-1503 (IVS6)). Corresponding mutations in domains II, III, and IV induced, in contrast, parallel shifts of activation and inactivation curves indicating a preserved coupling between both processes. Disruption between coupling of activation and inactivation was specific for mutations of Gly-432 in domain I. Mutations of Gly-432 removed inactivation irrespective of the changes in activation. In all four domains residues G/A/G/A are in close contact with larger bulky amino acids from neighboring S6 helices. These interactions apparently provide adhesion points, thereby tightly sealing the activation gate of Ca(V)1.2 in the closed state. Such a structural hypothesis is supported by changes in activation gating induced by mutations of the G/A/G/A residues. The structural implications for Ca(V)1.2 activation and inactivation gating are discussed. 相似文献
8.
A method employing isolated microspore culture was established for the androgenic embryogenesis of timothy (Phleum pratense L). Embryos/calli were obtained and green plants regenerated. The induction medium was PG-96 (1.0 mg l−1 2,4-D, 0.1 mg l−1 Kinetin) supplemented with 6% maltose monohydrate. Timothy microspore culture was genotype-dependent, among 12 genotypes,
6 produced embryos/calli and 4 produced green plants. Macerating the spikes with a blender and purifying the microspores at
a mannitol/maltose monohydrate interface gave a relatively high percentage of cell vitality. The optimum microspore developmental
stage was from the very late uninucleate stage to the binucleate stage. Heat shock promoted the initiation of microspore culture.
Over 150 regenerated green plants were obtained; in a random sample of 32 of these 65.6% were doubled haploids (6n=42). Albinism
was a problem in plant regeneration (9.3–22%). This paper is the first to describe timothy androgenic embryogenesis by isolated
microspore culture.
Received: 9 September 1999 / Revision received: 6 December 1999 / Accepted: 13 December 1999 相似文献
9.
Christine S Cheah Ruth E Westenbroek William H Roden Franck Kalume John C Oakley Laura A Jansen William A Catterall 《Channels (Austin, Tex.)》2013,7(6):468-472
CaV channels are multi-subunit protein complexes that enable inward cellular Ca2+ currents in response to membrane depolarization. We recently described structure-function studies of the intracellular α1 subunit domain I-II linker, directly downstream of domain IS6. The results show the extent of the linker’s helical structure to be subfamily dependent, as dictated by highly conserved primary sequence differences. Moreover, the difference in structure confers different biophysical properties, particularly the extent and kinetics of voltage and calcium-dependent inactivation. Timothy syndrome is a human genetic disorder due to mutations in the CaV1.2 gene. Here, we explored whether perturbation of the I-II linker helical structure might provide a mechanistic explanation for a Timothy syndrome mutant’s (human CaV1.2 G406R equivalent) biophysical effects on inactivation and activation. The results are equivocal, suggesting that a full mechanistic explanation for this Timothy syndrome mutation requires further investigation. 相似文献
10.