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991.
Albert Guisasola Mohannad Qurie Maria del Mar Vargas Carles Casas Juan A. Baeza 《Process Biochemistry》2009,44(7):689-695
The metabolism of denitrifying polyphosphate accumulating organisms (DPAO) is not completely known. Recent reports suggest the existence of two types of DPAOs: those that can use nitrate and nitrite as electron acceptors (nitrate-DPAO) and those that can only use nitrite (nitrite-DPAO). Then, the survival of nitrite-DPAO in nitrate reducing environments is due to the existence of flanking denitrifying species, which reduce nitrate to nitrite. This works aims at a better understanding of the nitrite-DPAO population. For this aim, a nitrite-DPAO population was previously selected in a SBR using nitrite as electron acceptor. Then, nitrate utilisation by nitrite-DPAO was studied within a short-term period (4 days) and within a long-term period (50 days) with simultaneous nitrite and nitrate additions. The results obtained clearly indicate that nitrite-DPAO fail to use nitrate as electron acceptor even after 50 days of periodic dosing of nitrate and agree with the dual DPAO theory. Moreover, this failure casts doubts on the feasibility of nitrite based EBPR systems (i.e. partial nitrification + nitrite-DPAO) because these systems will not be able to denitrify an occasional nitrate inlet, which will remain in the effluent. 相似文献
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G. Cecilia Toro Christer Wernstedt Carlos Medina Nicols Jaramillo Ulf Hellman Norbel Galanti 《Journal of cellular biochemistry》1992,49(3):266-271
Trypanosoma cruzi presents six histones electrophoretically resolved in three gel systems. Indirect evidence shows that one of these histones, name, corresponds to H4 in other species. We present evidence that histones is H4 by sequencing its amino terminal end. The amino terminal of T. cruzi histone H4, unlike that of other H4s examined thus far is not blocked. Moreover, this protein presents two variants. This partial amino acid sequence of T. cruzi histone H4 differs greatly from homologous sequences of human, yeast, or Tetrahymena. Since the conservatism of the core histones (H2A, H2B, H3, and H4) is clearly illustrated by comparative sequence analyses, the data shown here demonstrates that T. cruzi histone H4 is the most divergent reported. Quantitative analysis of the data suggests that the rate of substitutions in the histone H4 amino terminal sequence varies among different lineages. We postulate a slow-down in the evolutionary rate of histone H4 amino terminal domain in the metazoa branch related perhaps to the appearance of a novel function for this domain. 相似文献
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Fifteen genotypes of faba bean (Vicia faba L.) were inoculated with salt-tolerant Rhizobium leguminosarum biovar. viciae strain GRA 19 in solution culture with 0 (control) and 75 mM NaCl added immediately after transplanting. Genotypes varied in their tolerance of high levels of NaCl. Physiological parameters (dry weight of shoot and root, number and dry weight of nodules) were not affected by salinity in lines VF46, VF64 and VF112. Faba bean line VF60 was sensitive to salt stress. Host tolearance appeared to be a major requisite for nodulation and N2 fixation under salt stress. Tolerant line VF112 sustained nitrogen fixation under saline conditions. Activity of the ammonium assimilation enzymes glutamine synthetase and glutamate synthase, and soluble protein content, were reduced by salinity in all genotypes tested. Evidence presented here suggests a need to select faba bean genotypes that are tolerant to salt stress.Abbreviations ARA
acetylene reduction activity
- NADH-GOGAT
NADH-dependent glutamate synthase
- GS
glutamine synthetase 相似文献
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This study analyzes whether the release of nitric oxide (NO) and thromboxane A2 (TXA2) depends on the time lapsed since gonadal function is lost, and their correlation with the proliferation of vascular smooth muscle cells (VSMC) mediated by the epidermal growth factor receptor (EGFR). For this purpose, aortic and mesenteric artery segments from control and 6-weeks or 5-months orchidectomized rats were used to measure NO and TXA2 release. The results showed that the basal and acetylcholine (ACh)-induced NO release were decreased 6 weeks post-orchidectomy both in aorta and mesenteric artery, but were recovered 5 months thereafter up to levels similar to those found in arteries from control rats. The basal and ACh-induced TXA2 release increased in aorta and mesenteric artery 6 weeks post-orchidectomy, and was maintained at high levels 5 months thereafter. Since we previously observed that orchidectomy, which decreased testosterone level, enlarged the muscular layer of mesenteric arteries, the effect of testosterone on VSMC proliferation was analyzed. The results showed that treatment of cultured VSMC with testosterone downregulated mitogenic signaling pathways initiated by the ligand-dependent activation of the EGFR. In contrast, the EGFR pathways were constitutively active in mesenteric arteries of long-term orchidectomized rats. Thus, the exposure of mesenteric arteries from control rats to epidermal growth factor (EGF) induced the activation of EGFR signaling pathways. However, the addition of EGF to arteries from orchidectomized rats failed to induce a further activation of these pathways. In conclusion, this study shows that the release of NO depends on the time lapsed since the gonadal function is lost, while the release of TXA2 is already increased after short periods post-orchidectomy. The alterations in these signaling molecules could contribute to the constitutive activation of the EGFR and its downstream signaling pathways after long period post-orchidectomy enhancing the proliferation of the vascular muscular layer. 相似文献