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91.
Ujjal K. Nath Gayatri Goswami Rosemarie Clemens Heiko C. Becker Christian Möllers 《Molecular breeding : new strategies in plant improvement》2009,23(1):125-138
Erucic acid (22:1) is a valuable renewable resource for the oleochemical industry. Currently available high erucic acid rapeseed
cultivars contain only about 50% erucic acid in the seed oil. A substantial increase of the erucic acid content of the rapeseed
oil could increase market prospects. The transgenic line TNKAT, over expressing the rapeseed fatty acid elongase gene (fae1) and expressing the Ld-LPAAT gene from Limnanthes douglasii was crossed with the line 6575-1 HELP (high erucic and low polyunsaturated fatty acid). A from the F1 plants produced population of 90 doubled haploid (DH) lines was tested in a greenhouse with three replicates. Parental lines
TNKAT and 6575-1 HELP contained 46 and 50% erucic acid in the seed oil, respectively. In the DH population the erucic acid
content ranged between 35 and 59%. The Ld-LPAAT + Bn-fae1.1 transgene showed a 1:1 segregation. The transgenic DH lines contained up to 8% trierucolyglycerol, but surprisingly had
a by 2.3% lower erucic acid content compared to the non-transgenic segregants. Results indicated that the ectopically expressed
fae1.1 gene may not be functional. The DH population also showed a large quantitative variation for PUFA content ranging from
6 to 28% (TNKAT: 21%, 6575-1 HELP: 8%). Regression analysis showed that in the DH population a 10% reduction in PUFA content
led to a 4.2% increase in erucic acid content. Development of locus specific PCR primers for the two resident erucic acid
genes fae1.1 (A-genome) and fae1.2 genes (C-genome) of rapeseed allowed sequencing of the respective alleles from TNKAT and 6575-1 HELP. Single nucleotide
polymorphisms were only found for the fae1.1 gene. Use of allele specific fae1.1 PCR primers, however, did not reveal a significant effect of the fae1.1 allele from either parent on erucic acid content. The high erucic acid low polyunsaturated fatty acid DH lines and the
fae1 locus specific primers developed in the present study should be useful in future studies aimed at increasing erucic acid
content in rapeseed. 相似文献
92.
93.
De Weirdt R Possemiers S Vermeulen G Moerdijk-Poortvliet TC Boschker HT Verstraete W Van de Wiele T 《FEMS microbiology ecology》2010,74(3):601-611
Significant amounts of glycerol reach the colon microbiota daily through the diet and/or by in situ microbial production or release from desquamated epithelial cells. Some gut microorganisms may anaerobically reduce glycerol to 1,3-propanediol (1,3-PDO), with 3-hydroxypropanal as an intermediate. Accumulation of the latter intermediate may result in the formation of reuterin, which is known for its biological activity (e.g. antimicrobial properties). To date, glycerol metabolism in mixed cultures from the human colon has received little attention. Using in vitro batch incubations of faeces from 10 human individuals, we demonstrated that glycerol addition (140 mM) significantly affects the metabolism and composition of the microbial community. About a third of the samples exhibited rapid glycerol conversion, yielding proportionally higher levels of acetate and 1,3-PDO. In contrast, a slower glycerol metabolism resulted in higher levels of propionate. Furthermore, rapid glycerol metabolism correlated with significant shifts in the Lactobacillus-Enterococcus community, which were not observed in slower glycerol-metabolizing samples. As the conversion of glycerol to 1,3-PDO is a highly reducing process, we infer that the glycerol metabolism may act as an effective hydrogen sink. Given the importance of hydrogen-consuming processes in the gut, this work suggests that glycerol may have potential as a tool for modulating fermentation kinetics and profiles in the gastrointestinal tract. 相似文献
94.
S. Fricke C. Fricke C. Schimmelpfennig C. Oelkrug U. Schönfelder R. Blatz C. Zilch S. Faber N. Hilger M. Ruhnke A.C. Rodloff 《Journal of applied microbiology》2010,109(4):1150-1158
Aims: We established a real‐time PCR assay for the detection and strain identification of Candida species and demonstrated the ability to differentiate between Candida albicans the most common species, and also Candida parapsilosis, Candida glabrata, Candida tropicalis and Candida dubliniensis by LightCycler PCR and melting curve analysis. Methods and Results: The DNA isolation from cultures and serum was established using the QIAmp Tissue Kit. The sensitivity of the assay was ≥ 2 genome equivalents/assay. It was possible to differentiate all investigated Candida species by melting curve analysis, and no cross‐reaction to human DNA or Aspergillus species could be observed. Conclusions: The established real‐time PCR assay is a useful tool for the rapid identification of Candida species and a base technology for more complex PCR assays. Significance and Impact of the Study: We carried out initial steps in validation of a PCR assay for the detection and differentiation of medically relevant Candida species. The PCR was improved by generating PCR standards, additional generation of melting curves for species identification and the possibility to investigate different specimens simultaneously. 相似文献
95.
96.
In a detailed analysis of how limited seed dispersal can create spatial structuring of genetic variation, several nuclear microsatellites were assayed in seedlings from two forests of Pinus strobus, one old growth (OG) and the other (second site, SS) logged in ca. 1900. By using loci with a large number of alleles and new statistical methods on averaged spatial correlation coefficients, unusually precise estimates of spatial genetic structure were obtained, even though the structure was expected to be very weak. This high precision allowed the spatial patterns to be contrasted across loci and populations. At the OG site, the average spatial correlation coefficient for short distances (<15 m) exceeded its random expected value by 0.035, providing an indirect estimate of ca. 230 for Wright's neighborhood size. The value is similar to that estimated in a previous study of adult trees at OG and probably represents the natural level of spatial structure. A very similar value, 0.030, was obtained for seedlings at SS, despite the fact that unlike OG, genotypes of adults are randomly distributed, a likely result of logging. The results show that a single cycle of limited seed dispersal recreated the natural level of spatial structuring. In addition, one microsatellite, Rps50, had far greater amounts of allele variation, likely implicating it as having a higher mutation rate. The spatial structure of Rps50 also was significantly reduced, in a way that could be consistent with theoretical effects of high mutation rates (up to μ = 10(-2)). The choice of markers may influence estimates of spatial genetic structure. For example, if Rps50 is omitted the values are nearly doubled to 0.058 and 0.051 for SS and OG, respectively, both indicating a much smaller neighborhood size of ca. 100. 相似文献
97.
Zähringer U Lindner B Knirel YA van den Akker WM Hiestand R Heine H Dehio C 《The Journal of biological chemistry》2004,279(20):21046-21054
The facultative intracellular pathogen Bartonella henselae is responsible for a broad range of clinical manifestations, including the formation of vascular tumors as a result of increased proliferation and survival of colonized endothelial cells. This remarkable interaction with endotoxin-sensitive endothelial cells and the apparent lack of septic shock are considered to be due to a reduced endotoxic activity of the B. henselae lipopolysaccharide. Here, we show that B. henselae ATCC 49882(T) produces a deep-rough-type lipopolysaccharide devoid of O-chain and report on its complete structure and Toll-like receptor-dependent biological activity. The major short-chain lipopolysaccharide was studied by chemical analyses, electrospray ionization, and matrix-assisted laser desorption/ionization mass spectrometry, as well as by NMR spectroscopy after alkaline deacylation. The carbohydrate portion of the lipopolysaccharide consists of a branched trisaccharide containing a glucose residue attached to position 5 of an alpha-(2-->4)-linked 3-deoxy-d-manno-oct-2-ulosonic acid disaccharide. Lipid A is a pentaacylated beta-(1'-->6)-linked 2,3-diamino-2,3-dideoxy-glucose disaccharide 1,4'-bisphosphate with two amide-linked residues each of 3-hydroxydodecanoic and 3-hydroxyhexadecanoic acids and one residue of either 25-hydroxyhexacosanoic or 27-hydroxyoctacosanoic acid that is O-linked to the acyl group at position 2'. The lipopolysaccharide studied activated Toll-like receptor 4 signaling only to a low extent (1,000-10,000-fold lower compared with that of Salmonella enterica sv. Friedenau) and did not activate Toll-like receptor 2. Some unusual structural features of the B. henselae lipopolysaccharide, including the presence of a long-chain fatty acid, which are shared by the lipopolysaccharides of other bacteria causing chronic intracellular infections (e.g. Legionella and Chlamydia), may provide the molecular basis for low endotoxic potency. 相似文献
98.
Schiller J Müller K Süss R Arnhold J Gey C Herrmann A Lessig J Arnold K Müller P 《Chemistry and physics of lipids》2003,126(1):85-94
In this study we demonstrated the combination of MALDI-TOF MS and TLC as a fast and powerful tool to investigate the phospholipid (PL) composition of organic extracts of bull spermatozoa. Since phosphatidylcholine (PC) is the dominant PL species, an adequate resolution of MALDI-TOF spectra for sphingomyelin (SM) or phosphatidylethanolamine (PE) was achieved only after previous PL separation by TLC. We found a poor diversity especially for PE and PC, mainly containing ether-linked fatty acids which were 1-palmityl-2-docosahexaenoyl-PL and the corresponding alkenyl-acyl compound (plasmalogen) 1-palmitenyl-2-docosahexaenoyl-PL. For PC, both lipids were quantified after phospholipase A2 digestion to represent 44.2 and 37.2%, respectively, of the total PC. In contrast, the diacyl-PC content of bull spermatozoa was comparatively low (18.6% of total PC). In the presence of trifluoroacetic acid (TFA), which is routinely added to the MALDI-TOF matrix to improve the signal to noise ratio, a high lysophospholipid (LPL) content was detected in the PL extracts of bull spermatozoa, whereas TLC did not reveal significant amounts of LPL. The TFA mediated hydrolysis of the acid-labile alkenyl-acyl PL to the corresponding LPL was shown to cause this discrepancy. This assumption was verified by analysing the PL composition by MALDI-TOF MS before and after (i) digestion of sperm cell lipids with phospholipase A2 and (ii) exposition of spermatozoa to HCl fumes. We conclude that the analysis of samples containing alkenyl-acyl-PL by MALDI-TOF has to be performed with great caution. 相似文献
99.
Connolly KM Smith BT Pilpa R Ilangovan U Jung ME Clubb RT 《The Journal of biological chemistry》2003,278(36):34061-34065
Many surface proteins are anchored to the cell wall by the action of sortase enzymes, a recently discovered family of cysteine transpeptidases. As the surface proteins of human pathogens are frequently required for virulence, the sortase-mediated anchoring reaction represents a potential target for new anti-infective agents. It has been suggested that the sortase from Staphylococcus aureus (SrtA), may use a similar catalytic strategy as the papain cysteine proteases, holding its Cys184 side chain in an active configuration through a thiolate-imidazolium ion interaction with residue His120. To investigate the mechanism of transpeptidation, we have synthesized a peptidyl-vinyl sulfone substrate mimic that irreversibly inhibits SrtA. Through the study of the pH dependence of SrtA inhibition and NMR, we have estimated the pKas of the active site thiol (Cys184) and imidazole (His120) to be approximately 9.4 and 7.0, respectively. These measurements are inconsistent with the existence of a thiolate-imidazolium ion pair and suggest a general base catalysis mechanism during transpeptidation. 相似文献
100.
The search for cell-surface markers that can distinguish T helper 1 (T(H)1) cells from T(H)2 cells has led to the identification of a new gene family, encoding the T-cell immunoglobulin mucin (TIM) proteins, some of which are differentially expressed by T(H)1 and T(H)2 cells. The role of the TIM-family proteins in immune regulation is just beginning to emerge. Here, we describe the various TIM-family members in mice and humans, and discuss the genetic and functional evidence for their role in regulating autoimmune and allergic diseases. 相似文献