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A sensitive and highly reproducible assay for N-acetylmuramoyl-L-alanine amidase (EC 3.5.1.28) was devised, based on specific and homogeneous L-[14C]alanine labeling of the substrate, the peptidoglycan. The method involves partial purification of both the enzyme and the substrate and monitoring the muropeptide cleavage by coupling fluorodinitrobenzene to freed L-alanine NH2 groups. After acid hydrolysis of the substrate, the resulting DNP-L-alanine and L-alanine are separated by TLC, and radioactive counts in relevant spots are determined. Application of the method to the autolysin-endowed strain and an autolysis-deficient flaD-bearing mutant has revealed (i) that the N-acetylmuramoyl-L-alanine amidase behaves like an endoenzyme with an apparent Kcat(s-1) of 40, and (ii) that the residual enzyme activity in the flaD bearing strain amounts to 2.5 (+/- 0.1)% of that of the parent strain. 相似文献
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JF Yuan SJ Zhang O Jafer RA Furlong OE Chausiaux CA Sargent GH Zhang NA Affara 《BMC microbiology》2009,9(1):246
Background
Pseudorabies virus (PRV) is an alphaherpesviruses whose native host is pig. PRV infection mainly causes signs of central nervous system disorder in young pigs, and respiratory system diseases in the adult. 相似文献26.
Anthony Stuart Gilchrist Deborah CA Shearman Marianne Frommer Kathryn A Raphael Nandan P Deshpande Marc R Wilkins William B Sherwin John A Sved 《BMC genomics》2014,15(1)
Background
The tephritid fruit flies include a number of economically important pests of horticulture, with a large accumulated body of research on their biology and control. Amongst the Tephritidae, the genus Bactrocera, containing over 400 species, presents various species groups of potential utility for genetic studies of speciation, behaviour or pest control. In Australia, there exists a triad of closely-related, sympatric Bactrocera species which do not mate in the wild but which, despite distinct morphologies and behaviours, can be force-mated in the laboratory to produce fertile hybrid offspring. To exploit the opportunities offered by genomics, such as the efficient identification of genetic loci central to pest behaviour and to the earliest stages of speciation, investigators require genomic resources for future investigations.Results
We produced a draft de novo genome assembly of Australia’s major tephritid pest species, Bactrocera tryoni. The male genome (650 -700 Mbp) includes approximately 150Mb of interspersed repetitive DNA sequences and 60Mb of satellite DNA. Assessment using conserved core eukaryotic sequences indicated 98% completeness. Over 16,000 MAKER-derived gene models showed a large degree of overlap with other Dipteran reference genomes. The sequence of the ribosomal RNA transcribed unit was also determined. Unscaffolded assemblies of B. neohumeralis and B. jarvisi were then produced; comparison with B. tryoni showed that the species are more closely related than any Drosophila species pair. The similarity of the genomes was exploited to identify 4924 potentially diagnostic indels between the species, all of which occur in non-coding regions.Conclusions
This first draft B. tryoni genome resembles other dipteran genomes in terms of size and putative coding sequences. For all three species included in this study, we have identified a comprehensive set of non-redundant repetitive sequences, including the ribosomal RNA unit, and have quantified the major satellite DNA families. These genetic resources will facilitate the further investigations of genetic mechanisms responsible for the behavioural and morphological differences between these three species and other tephritids. We have also shown how whole genome sequence data can be used to generate simple diagnostic tests between very closely-related species where only one of the species is scaffolded.Electronic supplementary material
The online version of this article (doi:10.1186/1471-2164-15-1153) contains supplementary material, which is available to authorized users. 相似文献27.
Sulfate reduction and S-oxidation in a moorland pool sediment 总被引:1,自引:2,他引:1
In an oligotrophic moorland pool in The Netherlands, S cycling near the sediment/water boundary was investigated by measuring (1) SO4
2– reduction rates in the sediment, (2) depletion of SO4
2– in the overlying water column and (3) release of35S from the sediment into the water column. Two locations differing in sediment type (highly organic and sandy) were compared, with respect to reduction rates and depletion of SO4
2– in the overlying water.Sulfate reduction rates in sediments of an oligotrophic moorland pool were estimated by diagenetic modelling and whole core35SO4
2– injection. Rates of SO4
2– consumption in the overlying water were estimated by changes in SO4
2– concentration over time in in situ enclosures. Reduction rates ranged from 0.27–11.2 mmol m–2 d–1. Rates of SO4
2– uptake from the enclosed water column varied from –0.5, –0.3 mmol m–2 d–1 (November) to 0.43–1.81 mmol m–2 d–1 (July, August and April). Maximum rates of oxidation to SO4
2– in July 1990 estimated by combination of SO4
2– reduction rates and rates of in situ SO4
2– uptake in the enclosed water column were 10.3 and 10.5 mmol m–2 d–1 at an organic rich and at a sandy site respectively.Experiments with35S2– and35SO4
2– tracer suggested (1) a rapid formation of organically bound S from dissimilatory reduced SO4
2– and (2) the presence of mainly non SO4
2–-S derived from reduced S transported from the sediment into the overlying water. A35S2– tracer experiment showed that about 7% of35S2– injected at 1 cm depth in a sediment core was recovered in the overlying water column.Sulfate reduction rates in sediments with higher volumetric mass fraction of organic matter did not significantly differ from those in sediments with a lower mass fraction of organic matter.Corresponding author 相似文献
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Plusquin M Stevens AS Van Belleghem F Degheselle O Van Roten A Vroonen J Blust R Cuypers A Artois T Smeets K 《The International journal of developmental biology》2012,56(1-3):183-191
The planarian Schmidtea mediterranea is a well-studied model organism for developmental research, because of its stem cell system. This characteristic also provides a unique opportunity to study stress management and the effect of stress on stem cells. In this study, we characterised the stress signature at different levels of biological organization. The carcinogenic metal cadmium was used as a model chemical stressor. We focused on stem cell activity and its interaction with other known stress parameters. Here, we have found that S. mediterranea is able to cope with high internal levels of cadmium. At endpoints such as size and mobility, cadmium-related stress effects were detected but all of these responses were transient. Correspondingly, cadmium exposure led to an elevated mitotic activity of the neoblasts, at the same time points when the other responses disappeared. At the molecular level, we observed redox-related responses that can be linked with both repair as well as proliferation mechanisms. Together, our results suggest that these animals have a high plasticity. The induction of stem cell activity may underlie this 'restoring' effect, although a carcinogenic outcome after longer exposure times cannot be excluded. 相似文献
30.
Matthew P. Johnson Linda T. Roten Thomas D. Dyer Christine E. East Siri Forsmo John Blangero Shaun P. Brennecke Rigmor Austgulen Eric K. Moses 《Human genetics》2009,126(5):655-666
Preeclampsia is a heritable pregnancy disorder that presents new onset hypertension and proteinuria. We have previously reported
genetic linkage to preeclampsia on chromosomes 2q, 5q and 13q in an Australian/New Zealand (Aust/NZ) familial cohort. This
current study centered on identifying the susceptibility gene(s) at the 5q locus. We first prioritized candidate genes using
a bioinformatic tool designed for this purpose. We then selected a panel of known SNPs within ten prioritized genes and genotyped
them in an extended set of the Aust/NZ families and in a very large, independent Norwegian case/control cohort (1,139 cases,
2,269 controls). In the Aust/NZ cohort we identified evidence of a genetic association for the endoplasmic reticulum aminopeptidase
1 (ERAP1) gene (rs3734016, P
uncorr = 0.009) and for the endoplasmic reticulum aminopeptidase 2 (ERAP2) gene (rs2549782, P
uncorr = 0.004). In the Norwegian cohort we identified evidence of a genetic association for ERAP1 (rs34750, P
uncorr = 0.011) and for ERAP2 (rs17408150, P
uncorr = 0.009). The ERAP2 SNPs in both cohorts remained statistically significant (rs2549782, P
corr = 0.018; rs17408150, P
corr = 0.039) after corrections at an experiment-wide level. The ERAP1 and ERAP2 genes encode enzymes that are reported to play a role in blood pressure regulation and essential hypertension in addition
to innate immune and inflammatory responses. Perturbations within vascular, immunological and inflammatory pathways constitute
important physiological mechanisms in preeclampsia pathogenesis. We herein report a novel preeclampsia risk locus, ERAP2, in a region of known genetic linkage to this pregnancy-specific disorder. 相似文献