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121.
Facile labeling of oligosaccharides (acidic and neutral) in a nonselective
manner was achieved with highly fluorescent anthranilic acid (AA,
2-aminobenzoic acid) (more than twice the intensity of 2- aminobenzamide,
AB) for specific detection at very high sensitivity. Quantitative labeling
in acetate-borate buffered methanol (approximately pH 5.0) at 80 degreesC
for 60 min resulted in negligible or no desialylation of the
oligosaccharides. A high resolution high performance liquid chromatographic
method was developed for quantitative oligosaccharide mapping on a
polymeric-NH2bonded (Astec) column operating under normal phase and anion
exchange (NP-HPAEC) conditions. For isolation of oligosaccharides from the
map by simple evaporation, the chromatographic conditions developed use
volatile acetic acid-triethylamine buffer (approximately pH 4.0) systems.
The mapping and characterization technology was developed using well
characterized standard glycoproteins. The fluorescent oligosaccharide maps
were similar to the maps obtained by the high pH anion-exchange
chromatography with pulsed amperometric detection (HPAEC-PAD), except that
the fluorescent maps contained more defined peaks. In the map, the
oligosaccharides separated into groups based on charge, size, linkage, and
overall structure in a manner similar to HPAEC-PAD with contribution of
-COOH function from the label, anthranilic acid. However, selectivity of
the column for sialic acid linkages was different. A second dimension
normal phase HPLC (NP-HPLC) method was developed on an amide column (TSK
Gel amide-80) for separation of the AA labeled neutral complex type and
isomeric structures of high mannose type oligosaccharides. The
oligosaccharides labeled with AA are compatible with biochemical and
biophysical techniques, and use of matrix assisted laser desorption mass
spectrometry for rapid determination of oligosaccharide mass map of
glycoproteins is demonstrated. High resolution of NP-HPAEC and NP-HPLC
methods combined with mass spectrometry (MALDI-TOF) can provide an
effective technology for analyzing a wide repertoire of oligosaccharide
structures and for determining the action of both transferases and
glycosidases.
相似文献
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NELE ROGIERS FRANZ CONEN MARKUS FURGER RETO STÖCKLI WERNER EUGSTER 《Global Change Biology》2008,14(11):2613-2625
Grasslands cover about 40% of the ice‐free global terrestrial surface, but their quantitative importance in global carbon exchange with the atmosphere is still highly uncertain, and thus their potential for carbon sequestration remains speculative. Here, we report on CO2 exchange of an extensively used mountain hay meadow and pasture in the Swiss pre‐Alps on high‐organic soils (7–45% C by mass) over a 3‐year period (18 May 2002–20 September 2005), including the European summer 2003 heat‐wave period. During all 3 years, the ecosystem was a net source of CO2 (116–256 g C m?2 yr?1). Harvests and grazing cows (mostly via C export in milk) further increased these C losses, which were estimated at 355 g C m?2 yr?1 during 2003 (95% confidence interval 257–454 g C m?2 yr?1). Although annual carbon losses varied considerably among years, the CO2 budget during summer 2003 was not very different from the other two summers. However, and much more importantly, the winter that followed the warm summer of 2003 observed a significantly higher carbon loss when there was snow (133±6 g C m?2) than under comparable conditions during the other two winters (73±5 and 70±4 g C m?2, respectively). The continued annual C losses can most likely be attributed to the long‐term effects of drainage and peat exploitation that began 119 years ago, with the last significant drainage activities during the Second World War around 1940. The most realistic estimate based on depth profiles of ash content after combustion suggests that there is an 500–910 g C m?2 yr?1 loss associated with the decomposition of organic matter. Our results clearly suggest that putting efforts into preserving still existing carbon stocks may be more successful than attempts to increase sequestration rates in such high‐organic mountain grassland soils. 相似文献
125.
A. J. BLOOM M. A. ZWIENIECKI J. B. PASSIOURA L. B. RANDALL N. M. HOLBROOK & D. A. ST. CLAIR 《Plant, cell & environment》2004,27(8):971-979
The shoots of cultivated tomato (Lycopersicon esculentum cv. T5) wilt if their roots are exposed to chilling temperatures of around 5 °C. Under the same treatment, a chilling‐tolerant congener (Lycopersicon hirsutum LA 1778) maintains shoot turgor. To determine the physiological basis of this differential response, the effect of chilling on both excised roots and roots of intact plants in pressure chambers were investigated. In excised roots and intact plants, root hydraulic conductance declined with temperature to nearly twice the extent expected from the temperature dependence of the viscosity of water, but the response was similar in both species. The species differed markedly, however, in stomatal behaviour: in L. hirsutum, stomatal conductance declined as root temperatures were lowered, whereas the stomata of L. esculentum remained open until the roots reached 5 °C, and the plants became flaccid and suffered damage. Grafted plants with the shoots of one genotype and roots of another indicated that the differential stomatal behaviour during root chilling has distinct shoot and root components. 相似文献
126.
MIKAEL HEDRÉN SOFIE NORDSTRÖM DAVID STÅHLBERG 《Botanical journal of the Linnean Society. Linnean Society of London》2012,168(2):174-193
Dactylorhiza majalis subsp. sphagnicola is an allotetraploid marsh orchid derived from parents closely similar to present‐day D. incarnata and the western European form of D. maculata subsp. maculata, suggesting that it has a postglacial origin. It extends from northwestern continental Europe into areas formerly covered by the Weichselian ice sheet in mid‐Scandinavia. Here, we studied the variation at both the plastid and nuclear marker systems to describe the geographical variation in subsp. sphagnicola and its evolutionary history. We investigated whether subsp. sphagnicola is affected by secondary hybridization and gene flow from its parental lineages or from other allotetraploid marsh orchids, and we also compared subsp. sphagnicola with other allotetraploids of similar origins. We analysed 492 plants from 50 populations. Thirty‐seven populations were collected as potential Dactylorhiza majalis subsp. sphagnicola, five as subsp. sesquipedalis (D. elata), one as D. elata subsp. brennensis, one as subsp. calcifugiens, one as subsp. occidentalis and the remaining five as populations with some affinity to subsp. lapponica (including D. traunsteineri). All populations were analysed for plastid haplotypes and nuclear internal transcribed spacer (ITS) allele frequencies, and a subset of 43 populations was analysed for five nuclear microsatellite loci. Dactylorhiza majalis subsp. sphagnicola was dominated by a single plastid haplotype that was also dominant in western European D. maculata subsp. maculata, and most of the alternative haplotypes differed by only one mutation from the dominant one. There was more variation in nuclear microsatellites and ITS, and the variation was geographically structured in these markers. Subspecies occidentalis and calcifugiens shared haplotypes with subsp. sphagnicola, whereas subsp. sesquipedalis and brennensis had other haplotypes. Dactylorhiza majalis subsp. sphagnicola may have a postglacial origin within its present continental distribution. It has incorporated genetic material from D. maculata subsp. maculata by secondary hybridization and introgression, and some northern populations have assimilated strongly divergent haplotypes from the northeastern form of D. maculata subsp. maculata. Subspecies sphagnicola has also evolved morphologically divergent local populations in the north that do not differ from the typical populations in genetic markers. It may form mixed populations with other allotetraploid subspecies of D. majalis and, at least at one site, it has become integrated with subsp. lapponica, demonstrating that independently derived allotetraploids may contribute to a common gene pool. Subspecies calcifugiens seems to be derived from subsp. sphagnicola, and further studies based on a larger sample may confirm that it is better recognized as a variety. The so‐called D. elata subsp. brennensis is of hybrid origin and combines markers from subsp. sesquipedalis with markers from the D. majalis core complex, possibly subsp. majalis. The new combination Dactylorhiza majalis subsp. sesquipedalis (Willd.) H.A.Pedersen & Hedrén comb. nov. is provided. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 168 , 174–193. 相似文献
127.
Allison M Churcher Jose Martin Pujolar Massimo Milan Peter C Hubbard Rute ST Martins Jo?o L Saraiva Mar Huertas Luca Bargelloni Tomaso Patarnello Ilaria AM Marino Lorenzo Zane Adelino VM Canário 《BMC genomics》2014,15(1)
Background
The vertebrate brain plays a critical role in the regulation of sexual maturation and reproduction by integrating environmental information with developmental and endocrine status. The European eel Anguilla anguilla is an important species in which to better understand the neuroendocrine factors that control reproduction because it is an endangered species, has a complex life cycle that includes two extreme long distance migrations with both freshwater and seawater stages and because it occupies a key position within the teleost phylogeny. At present, mature eels have never been caught in the wild and little is known about most aspects of reproduction in A. anguilla. The goal of this study was to identify genes that may be involved in sexual maturation in experimentally matured eels. For this, we used microarrays to compare the gene expression profiles of sexually mature to immature males.Results
Using a false discovery rate of 0.05, a total of 1,497 differentially expressed genes were identified. Of this set, 991 were expressed at higher levels in brains (forebrain and midbrain) of mature males while 506 were expressed at lower levels relative to brains of immature males. The set of up-regulated genes includes genes involved in neuroendocrine processes, cell-cell signaling, neurogenesis and development. Interestingly, while genes involved in immune system function were down-regulated in the brains of mature males, changes in the expression levels of several receptors and channels were observed suggesting that some rewiring is occurring in the brain at sexual maturity.Conclusions
This study shows that the brains of eels undergo major changes at the molecular level at sexual maturity that may include re-organization at the cellular level. Here, we have defined a set of genes that help to understand the molecular mechanisms controlling reproduction in eels. Some of these genes have previously described functions while many others have roles that have yet to be characterized in a reproductive context. Since most of the genes examined here have orthologs in other vertebrates, the results of this study will contribute to the body of knowledge concerning reproduction in vertebrates as well as to an improved understanding of eel biology.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-799) contains supplementary material, which is available to authorized users. 相似文献128.
JENNIFER L. APPLE TONY GRACE ANTHONY JOERN PAUL ST. AMAND SAMANTHA M. WISELY 《Molecular ecology》2010,19(18):4012-4028
In this study, we used a comparative genome scan to examine patterns of population differentiation with respect to host plant use in Hesperotettix viridis, a Nearctic oligophagous grasshopper locally specialized on various Asteraceae including Solidago, Gutierrezia, and Ericameria. We identified amplified fragment length polymorphism (AFLP) loci with significantly elevated FST (outlier loci) in multiple different‐host and same‐host comparisons of populations while controlling for geographic distance. By comparing the number and identities of outlier loci in different‐host vs. same‐host comparisons, we found evidence of host plant‐related divergent selection for some population comparisons (Solidago‐ vs. Gutierrezia‐feeders), while other comparisons (Ericameria‐ vs. Gutierrezia‐feeders) failed to demonstrate a strong role for host association in population differentiation. In comparisons of Solidago‐ vs. Gutierrezia‐feeding populations, a relatively high number of outlier loci observed repeatedly in different‐host comparisons (35% of all outliers and 2.7% of all 625 AFLP loci) indicated a significant role for host‐related selection in contributing to overall genomic differentiation in this grasshopper. Mitochondrial DNA sequence data revealed a star‐shaped phylogeny with no host‐ or geography‐related structure, low nucleotide diversity, and high haplotype diversity, suggesting a recent population expansion. mtDNA data do not suggest a long period of isolation in separate glacial refugia but are instead more compatible with a single glacial refugium and more recent divergence in host use. Our study adds to research documenting heterogeneity in differentiation across the genome as a consequence of divergent natural selection, a phenomenon that may occur as part of the process of ecological speciation. 相似文献
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The structure of calcitonin isolated from salmon1 (SCT 1) has been recently established2 and confirmed by synthesis8. It possesses an exceptionally high level of activity, exhibiting about 20–50 times the hypocalcaemic potency of any other calcitonin isolated from mammalian species. 相似文献