共查询到20条相似文献,搜索用时 15 毫秒
1.
l-β-Haloalanines are physiologically active unnatural amino acids and they are useful intermediates for the synthesis of natural
and unnatural amino acids, S-linked glycopeptides, and lanthionines. In general l-β-haloalanines were prepared predominantly from l-serine via functional group transformation. Here we reported an alternative approach for the preparation of l-β-haloalanines via halogenation of protected l-cysteine esters which was obtained from l-cysteine or l-cystine, respectively. The mercapto group of protected l-cysteine esters was efficiently transformed to halo groups by triphenylphosphine/N-halosuccinimides. It has been proved to be a versatile desulfurization strategy via this functional group transformation. 相似文献
2.
This paper presents a preliminary study combining macrobotanical and phytolith analyses to explore crop processing at archaeological sites in Haryana and Rajasthan, northwest India. Current understanding of the agricultural strategies in use by populations associated with South Asia’s Indus Civilisation (3200–1900 bc) has been derived from a small number of systematic macrobotanical studies focusing on a small number of sites, with little use of multi-proxy analysis. In this study both phytolith and macrobotanical analyses are used to explore the organisation of crop processing at five small Indus settlements with a view to understanding the impact of urban development and decline on village agriculture. The differing preservation potential of the two proxies has allowed for greater insights into the different stages of processing represented at these sites: with macrobotanical remains allowing for more species-level specific analysis, though due to poor chaff presentation the early stages of processing were missed; however these early stages of processing were evident in the less highly resolved but better preserved phytolith remains. The combined analyses suggests that crop processing aims and organisation differed according to the season of cereal growth, contrary to current models of Indus Civilisation labour organisation that suggest change over time. The study shows that the agricultural strategies of these frequently overlooked smaller sites question the simplistic models that have traditionally been assumed for the time period, and that both multi-proxy analysis and rural settlements are deserving of further exploration. 相似文献
3.
Tamura M Togami J Ishiguro K Nakamura N Katsumoto Y Suzuki K Kusumi T Tanaka Y 《Plant cell reports》2003,21(5):459-466
Verbena (Verbena x hybrida), an important floricultural species, was successfully regenerated from stem segments on Murashige and Skoog's basal medium supplemented with thidiazuron and indole-3-acetic acid. A transformation system was developed using cvs. Temari Scarlet, Temari Sakura, Tapien Rose and TP-P2. Agrobacterium tumefaciens strain Agl0 harboring the sGFP gene was infected into stem segments. Transformation efficiency was improved by evaluating and manipulating the age of the plant material, the concentration of kanamycin in the medium during selection, and the length of the culture period in the dark. After 2-3 months of culture on the selection medium, GFP-positive shoots were obtained in all four of the cultivars tested. These shoots were successfully acclimated and set flowers within 2-3 months in a greenhouse. GFP was expressed in all of the organs including the floral parts. Stable genomic transformation was confirmed by Southern blot analysis. No morphological differences were observed between the transformed plants and their host plants. 相似文献
4.
Background
The presence of β-lactamases in Y. enterocolitica has been reported to vary with serovars, biovars and geographical origin of the isolates. An understanding of the β-lactamases in other related species is important for an overall perception of antibiotic resistance in yersiniae. The objective of this work was to study the characteristics of β-lactamases and their genes in strains of Y. intermedia and Y. frederiksenii, isolated from clinical and non-clinical sources in India. 相似文献5.
Kapil Tahlan Marcus A. Moore Susan E. Jensen 《Journal of industrial microbiology & biotechnology》2017,44(4-5):517-524
The δ-(l-α-aminoadipyl)-l-cysteinyl-d-valine (ACV) tripeptide is the first dedicated intermediate in the biosynthetic pathway leading to the penicillin and cephalosporin classes of β-lactam natural products in bacteria and fungi. It is synthesized nonribosomally by the ACV synthetase (ACVS) enzyme, which has been purified and partially characterized from many sources. Due to its large size and instability, many details regarding the reaction mechanism of ACVS are still not fully understood. In this review we discuss the chronology and associated methodology that led to the discovery of ACVS, some of the main findings regarding its activities, and some recent/current studies being conducted on the enzyme. In addition, we conclude with perspectives on what can be done to increase our understating of this very important protein in the future. 相似文献
6.
Background
Carotenoids are a group of C40 isoprenoid molecules that play diverse biological and ecological roles in plants. Tomato is an important vegetable in human diet and provides the vitamin A precursor β-carotene. Genes encoding enzymes involved in carotenoid biosynthetic pathway have been cloned. However, regulation of genes involved in carotenoid biosynthetic pathway and accumulation of specific carotenoid in chromoplasts are not well understood. One of the approaches to understand regulation of carotenoid metabolism is to characterize the promoters of genes encoding proteins involved in carotenoid metabolism. Lycopene β-cyclase is one of the crucial enzymes in carotenoid biosynthesis pathway in plants. Its activity is required for synthesis of both α-and β-carotenes that are further converted into other carotenoids such as lutein, zeaxanthin, etc. This study describes the isolation and characterization of chromoplast-specific Lycopene β-cyclase (CYC-B) promoter from a green fruited S. habrochaites genotype EC520061. 相似文献7.
Hiroki Saito Qingbo Yuan Yutaka Okumoto Kazuyuki Doi Atsushi Yoshimura Hiromo Inoue Masayoshi Teraishi Takuji Tsukiyama Takatoshi Tanisaka 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2009,119(2):315-323
A recently established rice breeding program in low latitudes aims to develop varieties with extremely long basic vegetative growth (BVG) periods and weak photoperiod sensitivities. The Taiwanese japonica variety Taichung 65 (T65) harbors a recessive allele ef1 at the Ef1 (Early flowering 1) locus, thereby exhibiting an extremely long BVG period. The previous reported functional allele Ehd1 (Early heading date 1), located on chromosome 10, encodes a B-type response regulator, thereby shortening the BVG period, whereas its nonfunctional allele ehd1 greatly prolongs the BVG period. A conventional analysis using F2 and F3 populations and a subsequent CAPS analysis based on the amino acid sequences of Ehd1 and ehd1 showed that Ef1 and Ehd1 were at the same locus. The CAPS analysis also indicated that the Taiwanese japonica varieties with extremely long BVG periods all harbor ef1, but that ef1 does not exist among indica and japonica varieties in the low latitudes. Since ef1 has not been found in any japonica varieties outside Taiwan, this allele might have originated in Taiwan. Sequence analysis revealed that the mutant allele ef1-h, which prolongs the BVG period even more than ef1 does, harbors an mPing insertion in exon 2, which causes the complete loss of gene function. Our results indicate that both ef1 or ef1-h alleles can be used as new gene sources in developing rice varieties with extremely long BVG periods for low latitudes. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
Recombinant Zantedeschia aethiopica agglutinin (ZAA) was expressed in Escherichia coli as N-terminal His-tagged fusion. After induction with isopropylthio-β-d-galactoside (IPTG), the recombinant ZAA was purified by metal-affinity chromatography. The purified ZAA protein was applied
in anti-fungal assay and the result showed that recombinant ZAA had anti-fungal activity towards leaf mold (Fulvia fulva), one of the most serious phytopathogenic fungi causing significant yield loss of crops. This study suggests that ZAA could
be an effective candidate in genetic engineering of plants for the control of leaf mold. 相似文献
9.
Erwinia carotovora subspecies betavasculorum, also known as E. betavasculorum and Pectobacterium betavasculorum, is a soil bacterium that has the capacity to cause root rot necrosis of sugarbeets. The qualitatively different pathogenicity exhibited by the virulent E. carotovora strain and two avirulent strains, a Citrobacter sp. and an Enterobacter cloacae, was examined using digital analysis of photographic evidence of necrosis as well as for carbohydrate, ethane, and ethylene
release compared with uninoculated potato tuber slices. Visual scoring of necrosis was superior to digital analysis of photographs.
The release of carbohydrates and ethane from potato tuber slices inoculated with the soft rot necrosis-causing Erwinia was significantly greater than that of potato tuber slices that had not been inoculated or that had been inoculated with
the nonpathogenic E. cloacae and Citrobacter sp. strains. Interestingly, ethylene production from potato slices left uninoculated or inoculated with the nonpathogenic
Citrobacter strain was 5- to 10-fold higher than with potato slices inoculated with the pathogenic Erwinia strain. These findings suggest that (1) carbohydrate release might be a useful measure of the degree of pathogenesis, or
relative virulence; and that (2) bacterial suppression of ethylene formation may be a critical step in root rot disease formation. 相似文献
10.
Cobucci-Ponzano B Conte F Rossi M Moracci M 《Extremophiles : life under extreme conditions》2008,12(1):61-68
Glycoside hydrolases form hyperthermophilic archaea are interesting model systems for the study of catalysis at high temperatures
and, at the moment, their detailed enzymological characterization is the only approach to define their role in vivo. Family
29 of glycoside hydrolases classification groups α-l-fucosidases involved in a variety of biological events in Bacteria and Eukarya. In Archaea the first α-l-fucosidase was identified in Sulfolobus solfataricus as interrupted gene expressed by programmed −1 frameshifting. In this review, we describe the identification of the catalytic
residues of the archaeal enzyme, by means of the chemical rescue strategy. The intrinsic stability of the hyperthermophilic
enzyme allowed the use of this method, which resulted of general applicability for β and α glycoside hydrolases. In addition,
the presence in the active site of the archaeal enzyme of a triad of catalytic residues is a rather uncommon feature among
the glycoside hydrolases and suggested that in family 29 slightly different catalytic machineries coexist. 相似文献
11.
Matías Maggi Natalia Damiani Sergio Ruffinengo David De Jong Judith Principal Martín Eguaras 《Experimental & applied acarology》2010,50(3):269-279
We undertook a field study to determine whether comb cell size affects the reproductive behavior of Varroa destructor under natural conditions. We examined the effect of brood cell width on the reproductive behavior of V. destructor in honey bee colonies, under natural conditions. Drone and worker brood combs were sampled from 11 colonies of Apis mellifera. A Pearson correlation test and a Tukey test were used to determine whether mite reproduction rate varied with brood cell
width. Generalized additive model analysis showed that infestation rate increased positively and linearly with the width of
worker and drone cells. The reproduction rate for viable mother mites was 0.96 viable female descendants per original invading
female. No significant correlation was observed between brood cell width and number of offspring of V. destructor. Infertile mother mites were more frequent in narrower brood cells. 相似文献
12.
The lipase Lip2 of the edible basidiomycete, Pleurotus sapidus, is an extracellular enzyme capable of hydrolysing xanthophyll esters with high efficiency. The gene encoding Lip2 was expressed
in Escherichia coli TOP10 using the gene III signal sequence to accumulate proteins in the periplasmatic space. The heterologous expression under
control of the araBAD promoter led to the high level production of recombinant protein, mainly as inclusion bodies, but partially
in a soluble and active form. A fusion with a C-terminal His tag was used for purification and immunochemical detection of
the target protein. This is the first example of a heterologous expression and periplasmatic accumulation of a catalytically
active lipase from a basidiomycete fungus. 相似文献
13.
I. V. Shamshev 《Entomological Review》2018,98(2):240-244
A new species of dance flies (Diptera, Empididae) of the Empis subgenus Pachymeria Stephens, 1829, E. (P.) roditakisi sp. n. from Greece is described and illustrated. 相似文献
14.
Nadiawati Alias Nor Muhammad Mahadi Abdul Munir Abdul Murad Farah Diba Abu Bakar Nik Azmi Nik Mahmood Rosli Md Illias 《World journal of microbiology & biotechnology》2009,25(4):561-572
A gene encoding endochitinase from Trichoderma virens UKM-1 was cloned and expressed in E. coli BL21 (DE3). Both the endochitinase gene and its cDNA sequences were obtained. The endochitinase gene encodes 430 amino acids
from an open reading frame comprising of 1,690 bp nucleotide sequence with three introns. The endochitinase was expressed
as soluble and active enzyme at 20°C when induced with 1 mM IPTG. Maximum activity was observed at 4 h of post-induction time.
SDS-PAGE showed that the purified endochitinase exhibited a single band with molecular weight of 42 kDa. Biochemical characterization
of the enzyme displayed a near neutral pH characteristic with an optimum pH at 6.0 and optimum temperature at 50°C. The enzyme
is stable between pH 3.0–7.0 and is able to retain its activity from 30 to 60°C. The presence of Mg2+ and Ca2+ ions increased the enzyme activity up to 20%. The purified enzyme has a strong affinity towards colloidal chitin and low
effect on ethyl cellulose and D-cellubiose which are non-chitin related substrates. HPLC analysis from the chitin hydrolysis
showed the release of (GlcNAc)3, (GlcNAc)2 and GlcNAc, in which (GlcNAc)2 was the main product. 相似文献
15.
There are three most important bacterial causative agents of serious infections that could be misused for warfare purposes: Bacillus anthracis (the causative agent of anthrax) is the most frequently mentioned one; however, Fracisella tularensis (causing tularemia) and Yersinia pestis (the causative agent of plague) are further bacterial agents enlisted by Centers for Disease Control and Prevention into the category A of potential biological weapons. This review intends to summarize basic information about these bacterial agents. Military aspects of their pathogenesis and the detection techniques suitable for field use are discussed. 相似文献
16.
17.
Annaliese S. Mason Erin E. Higgins Rod J. Snowdon Jacqueline Batley Anna Stein Christian Werner Isobel A. P. Parkin 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2017,130(4):621-633
The Brassica napus 60K Illumina Infinium? SNP array has had huge international uptake in the rapeseed community due to the revolutionary speed of acquisition and ease of analysis of this high-throughput genotyping data, particularly when coupled with the newly available reference genome sequence. However, further utilization of this valuable resource can be optimized by better understanding the promises and pitfalls of SNP arrays. We outline how best to analyze Brassica SNP marker array data for diverse applications, including linkage and association mapping, genetic diversity and genomic introgression studies. We present data on which SNPs are locus-specific in winter, semi-winter and spring B. napus germplasm pools, rather than amplifying both an A-genome and a C-genome locus or multiple loci. Common issues that arise when analyzing array data will be discussed, particularly those unique to SNP markers and how to deal with these for practical applications in Brassica breeding applications. 相似文献
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19.
Mewa Singh Tephillah Jeyaraj U. Prashanth Werner Kaumanns 《International journal of primatology》2011,32(1):167-176
Socioecology suggests that female distribution in space is determined by the distribution of food resources and the male distribution
is influenced by female distribution. Though studies have traditionally focused on females, males have received increasing
attention in recent years. We compared male–male relationships in lion-tailed macaques and bonnet macaques. Because bonnet
macaques have a high adult male:female sex ratio and are seasonal breeders whereas lion-tailed macaques have a low adult male:female
sex ratio and are largely aseasonal breeders, we predicted that bonnet macaque males would be spatially and socially more
tolerant of each other and would have less linear dominance relationships than lion-tailed macaques. We recorded male–male
and male–female relationships in 1 group of wild macaques of each species via scan sampling and 1–0 sampling. The results
revealed that lion-tailed macaque males largely remained at a distance from each other whereas bonnet macaque males remained
in close proximity to one another. Lion-tailed macaque males were more agonistic toward each other whereas bonnet macaque
males showed more affiliative interactions. The dominance hierarchy among lion-tailed macaque males was more linear than among
bonnet macaque males. Our data support the hypothesis that the study of spatial structuring, temporality of interactions,
and linearity of social relationships may contribute to a better understanding of macaque social systems. 相似文献
20.