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排序方式: 共有392条查询结果,搜索用时 140 毫秒
71.
Gregory J. O. Martin David R. A. Hill Ian L. D. Olmstead Amanda Bergamin Melanie J. Shears Daniel A. Dias Sandra E. Kentish Peter J. Scales Cyrille Y. Botté Damien L. Callahan 《PloS one》2014,9(8)
Many species of microalgae produce greatly enhanced amounts of triacylglycerides (TAGs), the key product for biodiesel production, in response to specific environmental stresses. Improvement of TAG production by microalgae through optimization of growth regimes is of great interest. This relies on understanding microalgal lipid metabolism in relation to stress response in particular the deprivation of nutrients that can induce enhanced TAG synthesis. In this study, a detailed investigation of changes in lipid composition in Chlorella sp. and Nannochloropsis sp. in response to nitrogen deprivation (N-deprivation) was performed to provide novel mechanistic insights into the lipidome during stress. As expected, an increase in TAGs and an overall decrease in polar lipids were observed. However, while most membrane lipid classes (phosphoglycerolipids and glycolipids) were found to decrease, the non-nitrogen containing phosphatidylglycerol levels increased considerably in both algae from initially low levels. Of particular significance, it was observed that the acyl composition of TAGs in Nannochloropsis sp. remain relatively constant, whereas Chlorella sp. showed greater variability following N-deprivation. In both algae the overall fatty acid profiles of the polar lipid classes were largely unaffected by N-deprivation, suggesting a specific FA profile for each compartment is maintained to enable continued function despite considerable reductions in the amount of these lipids. The changes observed in the overall fatty acid profile were due primarily to the decrease in proportion of polar lipids to TAGs. This study provides the most detailed lipidomic information on two different microalgae with utility in biodiesel production and nutraceutical industries and proposes the mechanisms for this rearrangement. This research also highlights the usefulness of the latest MS-based approaches for microalgae lipid research. 相似文献
72.
Two-dimensional restriction analysis of the Bacillus subtilis genome: gene purification and ribosomal ribonucleic acid gene organization.
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With two-dimensional restriction enzyme analysis we have been able to cleave the Bacillus subtilis genome and resolve the resulting deoxyribonucleic acid (DNA) segments into discrete bands on agarose gels. A general procedure for gene purification has been developed by coupling multidimensional restriction analysis with a biological assay for gene detection. The organization of ribosomal ribonucleic acid (rRNA) genes was studied by hybridizing 16S and 23S rRNA probes to the two-dimensional DNA banding patterns. 相似文献
73.
Age at onset in two common neurodegenerative diseases is genetically controlled 总被引:16,自引:1,他引:16
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Li YJ Scott WK Hedges DJ Zhang F Gaskell PC Nance MA Watts RL Hubble JP Koller WC Pahwa R Stern MB Hiner BC Jankovic J Allen FA Goetz CG Mastaglia F Stajich JM Gibson RA Middleton LT Saunders AM Scott BL Small GW Nicodemus KK Reed AD Schmechel DE Welsh-Bohmer KA Conneally PM Roses AD Gilbert JR Vance JM Haines JL Pericak-Vance MA 《American journal of human genetics》2002,70(4):985-993
To identify genes influencing age at onset (AAO) in two common neurodegenerative diseases, a genomic screen was performed for AAO in families with Alzheimer disease (AD; n=449) and Parkinson disease (PD; n=174). Heritabilities between 40%–60% were found in both the AD and PD data sets. For PD, significant evidence for linkage to AAO was found on chromosome 1p (LOD = 3.41). For AD, the AAO effect of APOE (LOD = 3.28) was confirmed. In addition, evidence for AAO linkage on chromosomes 6 and 10 was identified independently in both the AD and PD data sets. Subsequent unified analyses of these regions identified a single peak on chromosome 10q between D10S1239 and D10S1237, with a maximum LOD score of 2.62. These data suggest that a common gene affects AAO in these two common complex neurodegenerative diseases. 相似文献
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78.
Molecular cloning of nif DNA from Azotobacter vinelandii. 总被引:6,自引:5,他引:1
Two clones which contained nif DNA were isolated from a clone bank of total EcoRI-digested Azotobacter vinelandii DNA. The clones carrying the recombinant plasmids were identified by use of the 32P-labeled 6.2-kilobase (kb) nif insert from pSA30 (which contains the Klebsiella pneumoniae nifK, nifD, and nifH genes) as a hybridization probe. Hybridization analysis with fragments derived from the nif insert of pSA30 showed that the 2.6-kb insert from one of the plasmids (pLB1) contains nifK whereas the 1.4-kb insert from the other plasmid (pLB3) contains nifD. Marker rescue tests using genetic transformation indicated that the 2.6-kb A. vinelandii nif fragment contains the wild-type alleles for the nif-6 and nif-38 mutations carried by Nif- strains UW6 and UW38. The 1.4-kb insert contains the wild-type allele for the nif-10 mutation carried by Nif- strain UW10. 相似文献
79.
Giuliano Meyer Guido Bottà Carlo Rossetti Dario Cremaschi 《The Journal of membrane biology》1990,118(2):107-120
Summary In rabbit gallbladder epithelium, a Na+/H+, Cl–/HCO
3
–
double exchange and a Na+–Cl– symport are both present, but experiments on intact tissue cannot resolve whether the two transport systems operate simultaneously. Thus, isolated apical plasma membrane vesicles were prepared. After preloading with Na+, injection into a sodium-free medium caused a stable intravesicular acidification (monitored with the acridine orange fluorescence quenching method) that was reversed by Na+ addition to the external solution. Although to a lesser extent, acidification took place also in experiments with an electric potential difference (PD) equal to 0. If a preset pH difference (pH) was imposed ([H+]in>[H+]out, PD=0), the addition of Na-gluconate to the external solution caused pH dissipation at a rate that followed saturation kinetics. Amiloride (10–4
m) reduced the pH dissipation rate. Taken together, these data indicate the presence of Na+ and H+ conductances in addition to an amiloride-sensitive, electroneutral Na+/H+ exchange.An inwardly directed [Cl–] gradient (PD=0) did not induce intravesicular acidification. Therefore, in this preparation, there was no evidence for the presence of a Cl–/OH– exchange.When both [Na+] and [Cl–] gradients (outwardly directed, PD=0) were present, fluorescence quenching reached a maximum 20–30 sec after vesicle injection and then quickly decreased. The decrease was not observed in the presence of a [Na+] gradient alone or the same [Na+] gradient with Cl– at equal concentrations at both sides. Similarly, the decrease was abolished in the presence of both Na+ and Cl– concentration gradients and hydrochlorothiazide (5×10–4
m). The decrease was not influenced by an inhibitor of Cl–/OH– exchange (10–4
m furosemide) or of Na+–K+–2Cl– symport (10–5
m bumetanide).We conclude that a Na+/H+ exchange and a Na+–Cl– symport are present and act simultaneously. This suggests that in intact tissue the Na+–Cl– symport is also likely to work in parallel with the Na+/H+ exchange and does not represent an induced homeostatic reaction of the epithelium when Na+/H+ exchange is inhibited. 相似文献
80.