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1.
While supertrees have been built for many vertebrate groups (notably birds, mammals and dinosaurs), invertebrates have attracted relatively little attention. The paucity of supertrees of arthropods is particularly surprising given their economic and ecological importance, as well as their overwhelming contribution to biodiversity. The absence of comprehensive archives of machine-readable source trees, coupled with the need for software implementing repeatable protocols for managing them, has undoubtedly impeded progress. Here we present a supertree of Achelata (spiny, slipper and coral lobsters) as a proof of concept, constructed using new supertree specific software (the Supertree Toolkit; STK) and following a published protocol. We also introduce a new resource for archiving and managing published source trees. Our supertree of Achelata is synthesised from morphological and molecular source trees, and represents the most complete species-level tree of the group to date. Our findings are consistent with recent taxonomic treatments, confirming the validity of just two families: Palinuridae and Scyllaridae; Synaxidae were resolved within Palinuridae. Monophyletic Silentes and Stridentes lineages are recovered within Palinuridae, and all sub-families within Scyllaridae are found to be monophyletic with the exception of Ibacinae. We demonstrate the feasibility of building larger supertrees of arthropods, with the ultimate objective of building a complete species-level phylogeny for the entire phylum using a divide and conquer strategy. 相似文献
2.
The purification and properties of sucrose synthetase from etiolated Phaseolus aureus seedlings 总被引:6,自引:0,他引:6
D P Delmer 《The Journal of biological chemistry》1972,247(12):3822-3828
3.
A study of bacterial surface oligosaccharides were investigated among
different strains of Neisseria gonorrhoeae to correlate structural features
essential for binding to the MAb 2C7. This epitope is widely expressed and
conserved in gonococcal isolates, characteristics essential to an effective
candidate vaccine antigen. Sample lipooligosaccharides (LOS), was prepared
by a modification of the hot phenol-water method from which de-O-acetylated
LOS and oligosaccharide (OS) components were analyzed by ES-MS-CID-MS and
ES-MSnin a triple quadrupole and an ion trap mass spectrometer,
respectively. Previously documented natural heterogeneity was apparent from
both LOS and OS preparations which was admixed with fragments induced by
hydrazine and mild acid treatment. Natural heterogeneity was limited to
phosphorylation and antenni extensions to the alpha-chain. Mild acid
hydrolysis to release OS also hydrolyzed the beta(1-->6) glycosidic
linkage of lipid A. OS structures were determined by collisional and
resonance excitation combined with MS and multistep MSn which provided
sequence information from both neutral loss, and nonreducing terminal
fragments. A comparison of OS structures, with earlier knowledge of MAb
binding, enzyme treatment, and partial acid hydrolysis indicates a generic
overlapping domain for 2C7 binding. Reoccurring structural features include
a Hepalpha(1-->3)Hepbeta(1-->5)KDO trisaccharide core branched on the
nonreducing terminus (Hep-2) with an alpha(1-->2) linked GlcNAc
(gamma-chain), and an alpha-linked lactose (beta-chain) residue. From the
central heptose (Hep-1), a beta(1-->4) linked lactose (alpha-chain),
moiety is required although extensions to this residue appear unnecessary.
相似文献
4.
Some of the general features of the pathway for l-tryptophan biosynthesis in cell cultures of Nicotiana tabccum var. Wisc. 38 have been investigated. The results of both isotope competition and direct-labeling experiments show that shikimic acid, anthranilic acid, indoleglycerol phosphate, and indole can serve as precursors to l-tryptophan in these cells, indicating that, in terms of its biochemical intermediates, the pathway is similar to that described for the bacteria and fungi. 相似文献
5.
The Biosynthesis of Sucrose and Nucleoside Diphosphate Glucoses in Phaseolus aureus 总被引:9,自引:7,他引:2 下载免费PDF全文
Sucrose-phosphate synthetase is detectable only in intact chloroplast preparations of Phaseolus aureus. In contrast, sucrose synthetase and uridine diphosphate glucose (UDP-glucose) pyrophosphorylase activities are low in extracts of photosynthetic tissues of P. aureus but are high in extracts of nonphotosynthetic tissues. Activities for ADP-, dTDP-, CDP-, and GDP-glucose pyrophosphorylases are generally higher in extracts of photosynthetic tissues of P. aureus than in extracts of nonphotosynthetic tissues. The high levels of sucrose synthetase and of UDP-glucose pyrophosphorylase found in dark-grown hypocotyls begin to decline about 4 hours after exposure to light at a rate of 50% every 3 hours. 相似文献
6.
Adaptation and growth of tomato cells on the herbicide 2,6-dichlorobenzonitrile leads to production of unique cell walls virtually lacking a cellulose-xyloglucan network 总被引:11,自引:4,他引:7 下载免费PDF全文
Suspension-cultured cells of tomato (Lycopersicon esculentum VF 36) have been adapted to growth on high concentrations of 2,6-dichlorobenzonitrile, an herbicide which inhibits cellulose biosynthesis. The mechanism of adaptation appears to rest largely on the ability of these cells to divide and expand in the virtual absence of a cellulose-xyloglucan network. Walls of adapted cells growing on 2,6-dichlorobenzonitrile also differ from nonadapted cells by having reduced levels of hydroxyproline in protein, both in bound and salt-elutable form, and in having a much higher proportion of homogalacturonan and rhamnogalacturonan-like polymers. Most of these latter polymers are apparently cross-linked in the wall via phenolic-ester and/or phenolic ether linkages, and these polymers appear to represent the major load-bearing network in these unusual cell walls. The surprising finding that plant cells can survive in the virtual absence of a major load-bearing network in their primary cell walls indicates that plants possess remarkable flexibility for tolerating changes in wall composition. 相似文献
7.
Conditions which induce a transmembrane electrical potential, positive with respect to the inside of membrane vesicles, result in a substantial (4–12-fold) stimulation of the activity of membrane-associated -glucan synthetases in a membrane preparation derived from the developing cotton (Gossypium hirsutum L.) fiber. Induction of electrical potentials which are negative with respect to the inside of the membrane vesicle results in little or no stimulation of -glucan synthesis. Those products whose synthesis is stimulated are mainly -1,3-glucan, but there is also a considerable increase in -1,4-glucan. No -1,4-glucan (starch) was detected in the reaction products. A transmembrane pH gradient was found to have no effect on -glucan synthesis. The results indicate that a transmembrane electrical potential can influence, either directly or indirectly, the activity of membrane-associated polysaccharide synthetases.Abbreviations UDP-glucose
uridine-5-diphosphoglucose
- PEG
polyethylene glycol
- BTP
bistrispropane (1,3-bis[tris(hydroxymethyl)methylamino]propane)
- MES
2(N-morpholino)ethanesulfonic acid
- VAL
valinomycin 相似文献
8.
Protoplasts isolated from cultured soybean cells (Glycine max (L.) Merr., cv. Mandarin) were used to study polysaccharide biosynthesis during the initial stages of cell wall-regeneration. Within minutes after the protoplasts were transferred to a wall-regeneration medium containing [14C]glucose, radioactivity was detected in a product which was chemically characterized as cellulose. The onset and accumulation of radioactivity into cellulose coincided with the appearance fibrils on the surface of protoplasts, as seen under the electron microscope. At these early stages, a variety of polysaccharide-containing polymers other than cellulose were also synthesized. Under conditions where the protoplasts were competent to synthesize cellulose from glucose, uridine diphosphate-[14C]glucose and guanosine diphosphate-[14C]glucose did not serve as effective substrates for cellulose synthesis. However, substantial amounts of label from uridine diphosphate glucose were incorporated into 1,3-glucan.Abbreviations ECM
extracellular material
- GLC
gas liquid chromatography
- GDP-glucose
guanosine diphosphate glucose
- UDP-glucose
uridine diphosphate glucose
- U
enzyme units as defined by Sigma Chemical Corp., St. Louis, Mo., USA 相似文献
9.
Dimethylsulfoxide as a potential tool for analysis of compartmentation in living plant cells 总被引:8,自引:7,他引:1 下载免费PDF全文
Delmer DP 《Plant physiology》1979,64(4):623-629
Data are presented which indicate that dimethylsulfoxide (DMSO) acts selectively on the plasma membrane of cultured tobacco cells, rendering it more permeable to small molecules, while having a far smaller effect on the permeability of the vacuolar membrane. The results which support this conclusion are: (a) DMSO (5 to 10%, by volume) causes complete release of [14C]tryptophan newly synthesized from [14C]indole while causing efflux of only about 20% of the total intracellular tryptophan pool; (b) similar concentrations of DMSO do not cause substantial release from these cells of phenolic compounds or preloaded neutral red, nor of β-cyanin from fresh beet discs; (c) kinetic studies of release of tryptophan and neutral sugars and of efflux of 86Rb+ show that DMSO selectively promotes rapid release of a portion of the total pool, followed by a substantially slower release of the remaining pool; (d) when tobacco cell protoplasts are incubated in the presence of 7.5% (by volume) DMSO, rapid lysis is observed concomitant with the release of intact vacuoles. These data indicate that a procedure involving a brief treatment of intact plant cells or tissues with DMSO may be used to assess the distribution of metabolites between cytoplasmic and vacuolar compartments. 相似文献
10.
This paper reports the purification and structural determination of the mannolipid shown previously (Ericson and Delmer 1977 Plant Physiol 59: 341-347) to serve as an intermediate in glycoprotein synthesis in cotyledons of Phaseolus vulgaris. The mannolipid was purified by chromatography in organic solvents on diethylaminoethyl-cellulose, followed by repeated steps of deacylation and rechromatography on Sephadex LH-20. Binding and elution behavior on diethylaminoethyl-cellulose was consistent with the presence of a monophosphate residue. Lability of the mannolipid to mild acid treatment as well as its resistance to hot phenol treatment or catalytic hydrogenation are consistent with the structure of a polyprenol having a saturated α-residue. After methanolysis, the chloroform-methanol-soluble portion of the mannolipid was analyzed by mass spectrometry. The fragmentation pattern obtained was nearly identical to that obtained from standard dolichol-phosphate. An intense ion at m/e 69 represented the ω-terminal isoprenoid residue, and repeating fragments separated by 68 mass units were observed up to m/e of > 1,200. All evidence supports the conclusion that the mannolipid is dolichol-monophosphate-mannose and thus provides further support for the concept that the processes involved in the glycosylation of protein in higher plants are similar to those known to occur in the animal kingdom. 相似文献