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81.
【背景】杨树溃疡病是一种主要由葡萄座腔菌引起的杨树枝干病害,危害严重。前期从杨树中分离到一株内生拮抗细菌N6-34,研究表明该菌株拮抗效果好,对多种植物病原菌均有较强的拮抗作用。【目的】对拮抗细菌N6-34产生的抗菌活性物质进行分离纯化,并鉴定了活性物质组分的结构。【方法】通过硫酸铵盐析、甲醇抽提、分子筛、高效液相色谱等方法分离纯化N6-34菌株的抗菌活性物质,并对其进行结构鉴定。【结果】N6-34菌株发酵液经多步分离纯化,共获得14个组分,其中有13个组分具有抗菌活性,经一级质谱分析,获得了13种抗菌活性组分的分子量;经二级质谱分析,将13种抗菌活性物质鉴定为Fengycin A或Fengycin B的同系物或同分异构体。【结论】从N6-34菌株发酵液中分离获得了13种抗菌成分,为杨树溃疡病的生物防治提供了理论依据。 相似文献
82.
83.
Masoodul Haque Ather H. Siddiqi Jawed Siddiqui 《International journal for parasitology》1990,20(8):1113-1115
Polyacrylamide gel electrophoresis of the two digenetic trematodes, Gigantocotyle explanalum from the liver and Gastrothylax crumenifer from the rumen of the water buffalo, Bubalus bubalis revealed the presence of at least six and seven isoenzymes of lactate dehydrogenase (LDH), respectively in a partially purified enzyme preparation. The respective host tissues showed five isoenzymes of LDH, which are characteristic to the vertebrates. Both parachloromercuribenzoate and iodoacetate affected the LDH activity of the parasites and host tissues differently. Spectrophotometric analysis also showed different specific activity and susceptibility to the action of thiol inhibitors. The host LDH was quite stable at 57°C for 30 min, but that of the parasites was less stable. 相似文献
84.
13NO3− was used to investigate patterns of NO3− influx into roots of barley plants (Hordeum vulgare L. cv Klondike) previously grown with (`induced') or without (`uninduced') a source of external NO3− ([NO3−]0). In both induced and uninduced plants, 13NO3− influx was biphasic in the range from 0.005 to 50 moles per cubic meter [NO3−]0. In the low concentration range (<1 mole per cubic meter for induced plants and <0.3 mole per cubic meter for uninduced plants), influx was saturable and Vmax and Km values for influx either increased or decreased according to NO3− pretreatment. By contrast, 13NO3− influx in the high concentration range revealed a strictly linear concentration dependence. These fluxes appeared to be mediated by a constitutive, rather than an inducible, transport system. 相似文献
85.
Mei-Fang Jin Xiao-Tian Quan Muhammad Zubair Siddiqi Qing-Zhen Liu Hong-Shan Yu Wan-Taek Im 《Journal of microbiology (Seoul, Korea)》2018,56(5):331-336
A Gram-positive, strictly aerobic, nonmotile, yellowish, coccus-rod-shaped bacterium (designated Gsoil 653T) isolated from ginseng cultivating soil was characterized using a polyphasic approach to clarify its taxonomic position. The strain Gsoil 653T exhibited optimal growth at pH 7.0 on R2A agar medium at 30°C. Phylogenetic analysis based on 16S rRNA gene sequence similarities, indicated that Gsoil 653T belongs to the genus Terrabacter of the family Humibacillus, and was closely related to Terrabacter tumescens DSM 20308T (98.9%), Terrabacter carboxydivorans PY2T (98.9%), Terrabacter terrigena ON10T (98.8%), Terrabacter terrae PPLBT (98.6%), and Terrabacter lapilli LR-26T (98.6%). The DNA G + C content was 70.5 mol%. The major quinone was MK-8(H4). The primary polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidyl-ethanolamine. The predominant fatty acids were iso-C15:0, iso-C16:0, iso-C14:0, and anteiso-C15:0, as in the case of genus Terrabacter, thereby supporting the categorization of strain Gsoil 653T. However, the DNA-DNA relatedness between Gsoil 653T and closely related strains of Terrabacter species was low at less than 31%. Moreover, strain Gsoil 653T could be both genotypically and phenotypically distinguished from the recognized species of the genus Terrabacter. This isolate, therefore, represents a novel species, for which the name Terrabacter ginsengisoli sp. nov. is proposed with the type strain Gsoil 653T (= KACC 19444T = LMG 30325T). 相似文献
86.
Measurements of size distributions are provided for the breakage of commercial packed bakers' yeast cells as a function of operating pressure and number of passes through a Manton Gaulin high-pressure homogenizer. A two parameter model was developed, based upon the use of a Boltzmann function, to simulate the changes in size distribution that accompany the cell breakage process. The effects of operating pressure and number of passes are incorporated in the model and the result is used to simulate the particle size distribution of the cell homogenate. The results show that there is little breakage below a threshold pressure of 115 bar and above which breakage is critically dependent upon the pressure and number of passes through the homogenizer. The analysis provides a means of studying the efficiency of centrifugation that may follow cell disruption and provides the basis for further studies of size distribution changes accompanying cell disruption. (c) 1996 John Wiley & Sons, Inc. 相似文献
87.
Compartmentation and flux characteristics of ammonium in spruce 总被引:1,自引:0,他引:1
Using 13NH
4
+
as a tracer, compartmental analyses for NH
4
+
were performed in non-mycorrhizal roots of intact Picea glauca (Moench) Voss. seedlings at four different concentration regimes of external NH
4
+
([NH
4
+
]o), i.e. 0, 10, 100, and 1500 M. Three kinetically distinct compartments were identified, with half-lives of exchange of approximately 2 s, 30 s, and 14 min, assumed to represent surface adsorption, Donnan free space, and cytoplasm, respectively. No significant differences were found in half-lives of exchange with changes in [NH
4
+
]o. Influx was calculated to be 0.96 mol·g–1·h–1 in N-deprived plants (measured at 10 M [NH
4
+
]o), while under steady-state conditions it was 0.21 mol·g–1h–1 at 10 M [NH
4
+
]o, 1.96 mol·g–1h·–1 at 100 M [NH
4
+
]o, and 6.45 mol·g–1·h–1 at 1.5 mM [NH
4
+
]o. Efflux measured over the same range constituted approximately 9% of influx in N-deprived plants, 10% at 10 M, 28% at 100 M, and 35% at 1.5 mM [NH
4
+
]o. Cytoplasmic [NH
4
+
] was estimated at 6 m M in N-deprived plants, 2 mM at 10 M [NH
4
+
]o, 14 mM at 100 M, and 33 mM at 1.5 mM. Free-space [NH
4
+
] was 84 M, 50 M, 700 M, and 8 mM, respectively. In comparison with previously published data on fluxes and compartmentation of NO
3
–
in white-spruce seedlings, results of this study identify a pronounced physiological preference of this species for NH
4
+
over NO
3
–
as an inorganic N source in terms of uptake and intracellular accumulation. The significant ecological importance of this N-source preference is discussed.The research was supported by a Natural Sciences and Engineering Research Council, Canada, grant to Dr. A.D.M. Glass and a University of British Columbia Graduate Fellowship to Herbert J. Kronzucker. Our thanks go to Dr. M. Adam and Mr. P. Culbert at the particle accelerator facility TRIUMF on the University of British Columbia campus for providing 13N, to Drs. R.D. Guy and S. Silim for providing plant material, and to Dr. M.Y. Wang, Mr. J. Bailey, Mr. J. Mehroke and Mr. P. Poon for essential assistance in experiments. 相似文献
88.
Molecular evolution of cytochrome c oxidase: rate variation among subunit VIa isoforms 总被引:3,自引:1,他引:2
Schmidt TR; Jaradat SA; Goodman M; Lomax MI; Grossman LI 《Molecular biology and evolution》1997,14(6):595-601
Cytochrome c oxidase (COX) consists of 13 subunits, 3 encoded in the
mitochondrial genome and 10 in the nucleus. Little is known of the role of
the nuclear-encoded subunits, some of which exhibit tissue-specific
isoforms. Subunit VIa is unique in having tissue-specific isoforms in all
mammalian species examined. We examined relative evolutionary rates for the
COX6A heart (H) and liver (L) isoform genes along the length of the
molecule, specifically in relation to the tissue-specific function(s) of
the two isoforms. Nonsynonymous (amino acid replacement) substitutions in
the COX6AH gene occurred more frequently than in the ubiquitously expressed
COX6AL gene. Maximum-parsimony analysis and sequence divergences from
reconstructed ancestral sequences revealed that after the ancestral COX6A
gene duplicated to yield the genes for the H and L isoforms, the sequences
encoding the mitochondrial matrix region of the COX VIa protein experienced
an elevated rate of nonsynonymous substitutions relative to synonymous
substitutions. This is expected for relaxed selective constraints after
gene duplication followed by purifying selection to preserve the
replacements with tissue-specific functions.
相似文献
89.
90.
Saima Nusrat Mohammad Khursheed Siddiqi Masihuz Zaman Nida Zaidi Mohammad Rehan Ajmal Parvez Alam Atiyatul Qadeer Ali Saber Abdelhameed Rizwan Hasan Khan 《PloS one》2016,11(7)
Exogenous drugs that are used as antidote against chemotheray, inflammation or viral infection, gets absorbed and interacts reversibly to the major serum transport protein i.e. albumins, upon entering the circulatory system. To have a structural guideline in the rational drug designing and in the synthesis of drugs with greater efficacy, the binding mechanism of an antineoplastic and anti-inflammatory drug Nordihydroguaiaretic acid (NDGA) with human and bovine serum albumins (HSA & BSA) were examined by spectroscopic and computational methods. NDGA binds to site II of HSA with binding constant (Kb) ~105 M-1 and free energy (ΔG) ~ -7.5 kcal.mol-1. It also binds at site II of BSA but with lesser binding affinity (Kb) ~105 M-1 and ΔG ~ -6.5 kcal.mol-1. The negative value of ΔG, ΔH and ΔS for both the albumins at three different temperatures confirmed that the complex formation process between albumins and NDGA is spontaneous and exothermic. Furthermore, hydrogen bonds and hydrophobic interactions are the main forces involved in complex formation of NDGA with both the albumins as evaluated from fluorescence and molecular docking results. Binding of NDGA to both the albumins alter the conformation and causes minor change in the secondary structure of proteins as indicated by the CD spectra. 相似文献