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881.
Identification of the mpl gene encoding UDP-N-acetylmuramate: L-alanyl-gamma-D-glutamyl-meso-diaminopimelate ligase in Escherichia coli and its role in recycling of cell wall peptidoglycan. 下载免费PDF全文
A gene, mpl, encoding UDP-N-acetylmuramate:L-alanyl-gamma-D-glutamyl-meso-diaminopimelat e ligase was recognized by its amino acid sequence homology with murC as the open reading frame yjfG present at 96 min on the Escherichia coli map. The existence of such an enzymatic activity was predicted from studies indicating that reutilization of the intact tripeptide L-alanyl-gamma-D-glutamyl-meso-diaminopimelate occurred and accounted for well over 30% of new cell wall synthesis. Murein tripeptide ligase activity could be demonstrated in crude extracts, and greatly increased activity was produced when the gene was cloned and expressed under control of the trc promoter. A null mutant totally lacked activity but was viable, showing that the enzyme is not essential for growth. 相似文献
882.
Mark A. Pook Rekhaben Thakrar Bruce Pottinger Brian Harding David Porteous Veronica van Heningen John Cowell Carol Jones Sue Povey Kay E. Davies Rajesh V. Thakker 《Human genetics》1996,97(6):742-749
EagI and NotI linking libraries were prepared in the lambda vector, EMBL5, from the mouse-human somatic cell hybrid 1W1LA4.9, which contains
human chromosomes 11 and Xp as the only human component. Individual clones containing human DNA were isolated by their ability
to hybridise with total human DNA and digested with SalI and EcoRI to identify the human insert size and single-copy fragments. The mean (± SD) insert sizes of the EagI and NotI clones were 18.3 ± 3.2 kb and 16.6 ± 3.6 kb, respectively. Regional localisation of 66 clones (52 EagI, 14 NotI) was achieved using a panel of 20 somatic cell hybrids that contained different overlapping deletions of chromosomes 11
or Xp. Thirty-nine clones (36 EagI, 3 NotI) were localised to chromosome 11; 17 of these were clustered in 11q13 and another nine were clustered in 11q14–q23.1. Twenty-seven
clones (16 EagI, 11 NotI) were localised to Xp and 10 of these were clustered in Xp11. The 66 clones were assessed for seven different microsatellite
repetitive sequences; restriction fragment length polymorphisms for five clones from 11q13 were also identified. These EagI and NotI clones, which supplement those previously mapped to chromosome 11 and Xp, should facilitate the generation of more detailed
maps and the identification of genes that are associated with CpG-rich islands.
Received: 27 December 1995 / Revised: 30 January 1996 相似文献
883.
Louise Warnich Peter N. Meissner Richard J. Hift Jan H. Louw Carel J. van Heerden Andries E. Retief 《Human genetics》1996,97(5):690-692
The gene for variegate porphyria (VP), an autosomal dominant disease with a high prevalence in South Africa, evidently due
to a founder effect, was previously mapped to chromosome 14q32. In the current study this localization was evaluated by linkage
and haplotype analyses using microsatellite markers spanning a region of more than 20 cM on chromosome 14q32. In many recent
studies linkage disequilibrium between disease and marker loci has been utilized to map genes in founder populations, but
we could not find any association between VP and the markers used in this study. Our data suggest that the allocation of VP
to chromosome 14q32 may be incorrect.
Received: 1 September 1995 / Revised: 1 November 1995 相似文献
884.
Fiber-specific regulation of Ca(2+)-ATPase isoform expression by thyroid hormone in rat skeletal muscle 总被引:1,自引:0,他引:1
885.
Summary We report here an efficient Arabidopsis leafdisc transformation protocol yielding an average transformation frequency of 1.6 transgenic shoots per leaf explant 4 weeks after the bacterial infection period. Subsequent cultivation in vitro is such that a high percentage (85–90%) of the primary transformants produces seeds with an average seed yield of 100–300 seeds per plant. This improved transformation protocol yields mainly (70%) transformants segregating for a single T-DNA locus of which 68% actually contain one T-DNA insert. The objective is to generate a pool of independent transformants harboring an activator T-DNA construct in a gene tagging approach to isolate genes involved in morphogenesis and auxin signal transduction.Abbreviations
2,4-D
2,4-dichlorophenoxyacetic acid
-
AGM
Arabidopsis growth medium
-
BAP
benzylaminopurine
-
CaMV
Cauliflower Mosaic Virus
-
CTAB
Hexadecyltrimethylammoniumbromide
-
DIG
digoxigenin
-
FeNaEDTA
Iron-sodium-ethylenedinitrilo tetraacetic acid complex
-
GUS
ß-Glucuronidase
-
IBA
indole-3-butyric acid
-
LB
left T-DNA border
-
MES
2-(N-morpholino) ethane sulfonic acid
-
MS
Murashige and Skoog medium
-
NAA
-naphthaleneacetic acid
-
RB
right T-DNA border 相似文献
886.
Rapid coral colonization of a recent lava flow following a volcanic eruption,Banda Islands,Indonesia 总被引:1,自引:0,他引:1
Compared to the catastrophic impacts of various environmental disturbances and the subsequent recovery of scleractinian coral communities from these events, little is known about the early successional dynamics of coral communities following major volcanic eruptions. The 1988 volcanic eruption of Gunung Api, Banda Islands, Indonesia, provided a unique opportunity to study the rate at which a reef-building coral community develops on an andesitic lava flow. Coral colonization was studied at three locations varying in substrate characteristics. Five years after the eruption, the sheltered lava flow supported a diverse coral community (124 species) with high coral cover
. Tabulate acroporids were a dominant component of the lava flow coral community, with some colonies measuring over 90 cm in diameter. Higher average coral diversity, coral abundance and cover were recorded on the andesitic lava flow than on an adjacent carbonate reef not covered by the lava, and on a substrate of unstable pyroclastic deposits located on the southwestern coast of the volcano. In some areas of high coral diversity and environmental stability, andesitic lava flows may create local hot-spots of coral diversity by providing a structurally complex, predator-free and stable substrate for the recruitment of coral species from the adjacent and regional species pools. 相似文献
887.
Associations between different agonistic and affiliative behavioural patterns of female domestic cats (Felis silvestris catus) were studied. In three groups of intact cats living in confinement frequencies of fourteen agonistic and affiliative behavioural
patterns were recorded. The technique of factor analysis (Principal Components Analysis followed by varimax rotation on a
dyads X behavioural patterns matrix) was used to detect clusters in these behavioural patterns. Five factors (or types of
interindividual relationships) were extracted per group. They accounted collectively for at least 77% of the total variance
present in the data. Although differences existed between groups with respect to behavioural patterns included in each factor,
four clusters of behaviours could be discriminated: (I) social rubbing, lordosis and rolling in front of partner (sexual behaviour),
(II) allogrooming, social sniffing, nosing, sniffing rear and treading (inspection-affiliative behaviour), (III) offensive
behaviour and staring, and (IV) defensive behaviour and staring. The role of these clusters in group living is discussed. 相似文献
888.
Daphnids respond to algae-associated odours 总被引:2,自引:0,他引:2
Using a Y-tube olfactometer, it was found that Daphnia galeatax hyalina moves to the arm with odour from either of two ediblealgal species (Scenedesmus acuminatus and Oscillatoria limnetica)rather than to the alternative arm with clean water. However,no differential response was observed when odours of the toxiccyanobacterium (Oscillatoria agardhu) were tested. We suggestthat odours associated with edible algae attract Daphnia whereasnon-edible algae do not elicit attraction of Daphnia. 相似文献
889.
G. Beldman L. A. M. van den Broek H. A. Schols M. J. F. Searle-van Leeuwen K. M. J. van Laere A. G. J. Voragen 《Biotechnology letters》1996,18(6):707-712
Summary A pectic polysaccharide from soy was degraded by a crude extracellular preparation of Aspergillus aculeatus. Besides monomeric sugars, an unknown oligosaccharide was produced, which was purified and identified as the dimer -Xyl
p
-(1,3)-GalA
p
. The enzyme responsible for the release of this dimer was purified and characterized as an exogalacturonase, which was not hindered by side-chains of xylose. 相似文献
890.
Electric field-induced charge recombination in Photosystem II (PS II) was studied in osmotically swollen spinach chloroplasts (blebs) by measurement of the concomitant chlorophyll luminescence emission (electroluminescence). A pronounced dependence on the redox state of the two-electron gate QB was observed and the earlier failure to detect it is explained. The influence of the QB/QB
– oscillation on electroluminescence was dependent on the redox state of the oxygen evolving complex; at times around one millisecond after flash illumination a large effect was observed in the states S2 and S3, but not in the state S4 (actually Z+S3). The presence of the oxidized secondary electron donor, tyrosine Z+, appeared to prevent expression of the QB/QB
– effect on electroluminescence, possibly because this effect is primarily due to a shift of the redox equilibrium between Z/Z+ and the oxygen evolving complex.Abbreviations BSA
bovine serum albumin
- EDTA
ethylene-diaminetetraacetic acid
- EL
electroluminescence
- FCCP
carbonylcyanide p-trifluoromethyloxyphenyl-hydrazone
- HEPESI
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- I
primary electron acceptor
- MOPS
3-(N-morpholino) propane sulfonic acid
- P680
primary electron donor of Photosystem II
- P700
primary electron donor of Photosystem I
- QA and QB
secondary and tertiary electron acceptors of Photosystem II
- Z
secondary electron donor (D1 Tyr 161) 相似文献