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1.
Summary The effects of CO2 enrichment on the growth, biomass partitioning, photosynthetic rates, and leaf nitrogen concentration of a grass, Bromus mollis (C3), were investigated at a favorable and a low level of nitrogen availability. Despite increases in root: shoot ratios, leaf nitrogen concentrations were decreased under CO2 enrichment at both nitrogen levels. For the low-nitrogen treatment, this resulted in lower photosynthetic rates measured at 650 l/l for the CO2-enriched plants, compared to photosynthetic rates measured at 350 l/l for the non-enriched plants. At higher nitrogen availability, photosynthetic rates of plants grown and measured at 650 l/l were greater than photosynthetic rates of the non-enriched plants measured at 350 l/l. Water use efficiency, however, was increased in enriched plants at both nitrogen levels. CO2 enrichment stimulated vegetative growth at both high and low nitrogen during most of the vegetative growth phase but, at the end of the experiment, total biomass of the high and low CO2 treatments did not differ for plants grown at low nitrogen availability. While not statistically significant, CO2 tended to stimulate seed production at high nitrogen and to decrease it at low nitrogen. 相似文献
2.
Sacco C. de Vries Hilbert Booij Peter Meyerink Gert Huisman H. Dayton Wilde Terry L. Thomas Ab van Kammen 《Planta》1988,176(2):196-204
Embryogenic suspension cultures of domesticated carrot (Daucus carota L.) are characterized by the presence of proembryogenic masses (PEMs) from which somatic embryos develop under conditions of low cell density in the absence of phytohormones. A culture system, referred to as starting cultures, was developed that allowed analysis of the emergence of PEMs in newly initiated hypocotyl-derived suspension cultures. Embryogenic potential, reflected by the number of FEMs present, slowly increased in starting cultures over a period of six weeks. Addition of excreted, high-molecular-weight, heat-labile cell factors from an established embryogenic culture considerably accelerated the acquisition of embryogenic potential in starting cultures. Analysis of [35S]methionine-labeled proteins excreted into the medium revealed distinct changes concomitant with the acquisition of embryogenic potential in these cultures. Analysis of the pattern of gene expression by in-vitro translation of total cellular mRNA from starting cultures with different embryogenic potential and subsequent separation of the [35S]methionine-labeled products by two-dimensional polyacrylamide gel electrophoresis demonstrated a small number of abundant in-vitro-translation products to be present in somatic embryos and in embryogenic cells but absent in nonembryogenic cells. Several other in-vitro-translation products were present in explants, non-embryogenic and embryogenic cells but were absent in somatic embryos. Hybridization of an embryoregulated complementary-DNA sequence, Dc3, to RNA extracted from starting cultures showed that the corresponding gene is expressed in somatic embryos and PEMs but not in non-embryogenic cells.Abbreviations 2,4-D
2,4-dichlorophenoxyacetic acid
- cDNA
complementary DNA
- PAGE
polyacrylamide gel electrophoresis
- PEM
proembryogenic mass 相似文献
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Three major somatic embryogenesis related proteins in Cichorium identified as PR proteins 总被引:3,自引:0,他引:3
Helleboid S Hendriks T Bauw G Inzé D Vasseur J Hilbert JL 《Journal of experimental botany》2000,51(348):1189-1200
In Cichorium hybrid clone '474' (C. intybus L., var. sativum x C. endivia L., var. latifolia), the direct somatic embryogenesis process in leaf tissues is accompanied by an overall increase in the amount of proteins secreted into the culture medium. Amongst these, three major protein bands of 38 kDa, 32 kDa and 25 kDa were found in the conditioned media. These extracellular protein bands accumulated in the medium of the embryogenic Cichorium hybrid up to 8-fold compared with those in the medium of a nonembryogenic variety. 32 and 25 kDa proteins were purified from the medium and their identities were determined as already described for 38 kDa beta-1,3-glucanases. To investigate their possible function in somatic embryogenesis, peptide sequences, serological relationships or biochemical properties revealed that there were at least two acidic chitinases of 32 kDa and one glycosylated osmotin-like protein of 25 kDa in the embryogenic culture medium. Comparing the amounts of the 38 kDa glucanases, the 32 kDa chitinases, and the 25 kDa osmotin-like protein present in the conditioned media of the embryogenic '474' hybrid and of a non-embryogenic variety, a 2-8-fold higher accumulation of these proteins was observed in the embryogenic hybrid culture medium. This may suggest that part of the accumulation of these three pathogenesis-related (PR) proteins could be correlated with the somatic embryogenesis process. Their possible involvement in this developmental process is discussed. 相似文献
5.
General method of rapid Smith/Birnstiel mapping adds for gap closure in shotgun microbial genome sequencing projects: application to Pseudomonas putida KT2440 下载免费PDF全文
Christian Weinel Burkhard Tümmler Helmut Hilbert Karen E. Nelson Claudia Kiewitz 《Nucleic acids research》2001,29(22):e110
A physical mapping strategy has been developed to verify and accelerate the assembly and gap closure phase of a microbial genome shotgun-sequencing project. The protocol was worked out during the ongoing Pseudomonas putida KT2440 genome project. A macro-restriction map was constructed by linking probe hybridisation of SwaI- or I-CeuI-restricted chromosomes to serve as a backbone for the quick quality control of sequence and contig assemblies. The library of PCR-generated SwaI linking probes was derived from the sequence assembly after 3- and 6-fold genome coverage. In order to support gap closure in regions with ambiguous assemblies such as the repetitive sequence of the seven ribosomal operons, high-resolution Smith/Birnstiel maps were generated by Southern hybridisation of pulsed-field gel electrophoresis-separated rare-cutter complete/frequent-cutter partial digestions with rare-cutter fragment end probes. Overall 1.5 Mb of the 6.1 Mb P.putida KT2440 genome has been subjected to high-resolution physical mapping in order to align assemblies generated from shotgun sequencing. 相似文献
6.
Shahinaz M. Gadalla Ruth M. Pfeiffer Sigurdur Y. Kristinsson Magnus Bj?rkholm James E. Hilbert Richard T. Moxley III Ola Landgren Mark H. Greene 《PloS one》2013,8(11)
Recent studies show that patients with myotonic dystrophy (DM) have an increased risk of specific malignancies, but estimates of absolute cancer risk accounting for competing events are lacking. Using the Swedish Patient Registry, we identified 1,081 patients with an inpatient and/or outpatient diagnosis of DM between 1987 and 2007. Date and cause of death and date of cancer diagnosis were extracted from the Swedish Cause of Death and Cancer Registries. We calculated non-parametric estimates of absolute cancer risk and cancer mortality accounting for the high non-cancer competing mortality associated with DM. Absolute cancer risk after DM diagnosis was 1.6% (95% CI=0.4-4%), 5% (95% CI=3-9%) and 9% (95% CI=6-13%) at ages 40, 50 and 60 years, respectively. Females had a higher absolute risk of all cancers combined than males: 9% (95% CI=4-14), and 13% (95% CI=9-20) vs. 2% (95%CI= 0.7-6) and 4% (95%CI=2-8) by ages 50 and 60 years, respectively) and developed cancer at younger ages (median age =51 years, range=22-74 vs. 57, range=43-84, respectively, p=0.02). Cancer deaths accounted for 10% of all deaths, with an absolute cancer mortality risk of 2% (95%CI=1-4.5%), 4% (95%CI=2-6%), and 6% (95%CI=4-9%) by ages 50, 60, and 70 years, respectively. No gender difference in cancer-specific mortality was observed (p=0.6). In conclusion, cancer significantly contributes to morbidity and mortality in DM patients, even after accounting for high competing DM mortality from non-neoplastic causes. It is important to apply population-appropriate, validated cancer screening strategies in DM patients. 相似文献
7.
Lennart Hilbert Shivaram Cumarasamy Nedjma B. Zitouni Michael C. Mackey Anne-Marie Lauzon 《Biophysical journal》2013
Naturally occurring groups of muscle myosin behave differently from individual myosins or small groups commonly assayed in vitro. Here, we investigate the emergence of myosin group behavior with increasing myosin group size. Assuming the number of myosin binding sites (N) is proportional to actin length (L) (N = L/35.5 nm), we resolve in vitro motility of actin propelled by skeletal muscle myosin for L = 0.2–3 μm. Three distinct regimes were found: L < 0.3 μm, sliding arrest; 0.3 μm ≤ L ≤ 1 μm, alternation between arrest and continuous sliding; L > 1 μm, continuous sliding. We theoretically investigated the myosin group kinetics with mechanical coupling via actin. We find rapid actin sliding steps driven by power-stroke cascades supported by postpower-stroke myosins, and phases without actin sliding caused by prepower-stroke myosin buildup. The three regimes are explained: N = 8, rare cascades; N = 15, cascade bursts; N = 35, continuous cascading. Two saddle-node bifurcations occur for increasing N (mono → bi → mono-stability), with steady states corresponding to arrest and continuous cascading. The experimentally measured dependence of actin sliding statistics on L and myosin concentration is correctly predicted. 相似文献
8.
Beno?t J Smagghe Anne-Sophie Blervacq Christelle Blassiau Jean-Pierre Decottignies Jean-Pierre Jacquot Mark S Hargrove Jean-Louis Hilbert 《Plant signaling & behavior》2007,2(1):43-49
Hemoglobins are ancient O2-binding proteins, ubiquitously found in eukaryotes. They have been categorized as symbiotic, nonsymbiotic and truncated hemoglobins. We have investigated the cellular localization of nonsymbiotic hemoglobin proteins during somatic embryogenesis in Cichorium hybrid leaves (Cichorium intybus L. var. sativum × C. endivia var. latifolia) using immunolocalization technique. These proteins were detected during the two steps of culture: induction and expression. In leaves, hemoglobins colocalised with plastids, which were dispersed in the parietal cytoplasm as well as in the two guard cells of a stomata, but not in epidermis cells. Upon induction of embryogenesis, in the dark, this pattern disappeared. During the induction phase, where competent cells reinitiate the cell cycle and prepare for mitosis, hemoglobins appeared initially near chloroplasts, and then in the vicinity of vascular vessels especially in the phloem and in cells surrounding the xylem vessels. When leaf fragments were transferred to another medium for the expression phase, hemoglobins were observed in the majority of the leaf blade cells and in small young embryos but not in the older ones. Hemoglobins were also detected in other leaves cells or tissues all along the process. The role of these nonsymbiotic hemoglobins during somatic embryogenesis is discussed.Key Words: chicory, immunolocalization, nonsymbiotic hemoglobin, somatic embryogenesis 相似文献
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