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51.
Said Heba Shehta Benmahmod Abdalbagi Basheer Ibrahim Ramadan Hassan 《World journal of microbiology & biotechnology》2018,34(12):1-14
World Journal of Microbiology and Biotechnology - Diversity and distribution pattern of ammonia-oxidizing archaea (AOA) were studied across a salinity gradient in the water column of Cochin Estuary... 相似文献
52.
Sekena H Abdel-Aziem Heba A.M. Abd El-Kader Faten M. Ibrahim Hafiza A Sharaf Aida I. El makawy 《Journal of Genetic Engineering and Biotechnology》2018,16(2):653-660
Microalgae provide a wealthy natural resource of bioactive compounds, which have many biological activities. Monosodium glutamate is a food additive that acts either as food preservatives or as tastiness enhancer. It was confirmed that monosodium glutamate poses a serious responsibility in the pathogenesis of anovulatory infertility. Therefore, the idea of this research was directed to reveal efficiency of Chlorella vulgaris and Spirulina platensis extracts against the ovarian dysfunction resulted due to monosodium glutamate consumption. Adult female albino mice were gavages orally monosodium glutamate alone or with either Chlorella vulgaris or Spirulina platensis aqueous extracts for 28?days. Female mice were subjected to superovulation to study the oocytes nuclear maturation stages. Histological and quantitative investigation was carried on ovaries. Biochemical assessment to measure the sex hormones level and ovarian enzymatic antioxidants was done. In addition, ovarian antioxidant mRNA genes were determined using quantitative PCR and Glyceraldehyde-3-phosphate dehydrogenase was used as an internal control. The result revealed that monosodium glutamate reduced the oocytes quality and maturation rate, while, both algae improve the oocyte quality and maturation rate than in monosodium glutamate group. Chlorella vulgaris and Spirulina platensis improved the monosodium glutamate ovarian tissue histological alteration, sex hormones content and raised the ovarian enzymatic antioxidants level. In addition, monosodium glutamate markedly diminished the Glutathione peroxidase, superoxide dismutase and catalase mRNA expressions, However, Chlorella vulgaris or Spirulina platensis upregulated the expression of genes close to control. In conclusion, Chlorella vulgaris and Spirulina platensis showed potential alleviative role against the monosodium glutamate ovarian dysfunction. 相似文献
53.
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55.
Sherihan El-sayed Kamel Metwally Abdalla A. El-Shanawani Lobna M. Abdel-Aziz Ahmed A. El-Rashedy Mahmoud E.S. Soliman Luca Quattrini Vito Coviello Concettina la Motta 《Bioorganic & medicinal chemistry letters》2017,27(20):4760-4764
A series of quinazolinone-based rhodanine-3-acetic acids was synthesized and tested for in vitro aldose reductase inhibitory activity. All the target compounds displayed nanomolar activity against the target enzyme. Compounds 3a, 3b, and 3e exhibited almost 3-fold higher activity as compared to the only marketed reference drug epalrestat. Structure-activity relationship studies indicated that bulky substituents at the 3-phenyl ring of the quinazolinone moiety are generally not tolerated in the active site of the enzyme. Insertion of a methoxy group on the central benzylidene ring was found to have a variable effect on ALR-2 activity depending on the nature of peripheral quinazolinone ring substituents. Removal of the acetic acid moiety led to inactive or weakly active target compounds. Docking and molecular dynamic simulations of the most active rhodanine-3-acetic acid derivatives were also carried out, to provide the basis for further structure-guided design of novel inhibitors. 相似文献
56.
Potato bacterial wilt suppression and plant health improvement after application of different antioxidants
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Shahenda M. A. Farag Kamel M.A. Elhalag Mohamed H. Hagag Abdel Salam M. Khairy Heba M. Ibrahim Moheb T. Saker Nevein A. S. Messiha 《Journal of Phytopathology》2017,165(7-8):522-537
Bacterial wilt caused by Ralstonia solanacearum is a devastating disease that often threatens potato production and exportation. The potential of four antioxidants (seaweed extract (SWE), yeast, chitosan and ascorbic acid (ASA)) in controlling the disease was evaluated in vitro, under glasshouse and field conditions. The field experiment was conducted in two naturally infested locations: Wardan, Giza (sandy soil), and Talia, Minufiya (silty clay soil). Only chitosan showed antibacterial properties against the pathogen in vitro. SWE, yeast and chitosan showed disease suppression under both glasshouse and field conditions. The disease suppression was accompanied by an increase in the ratio of soil copiotrophic to oligotrophic bacteria. The three antioxidants increased plant nitrogen content, decreased soil OM content and decreased C/N ratio. Disease suppression after chitosan application was clearly observed only in Wardan area, which was characterized by a higher soil alkalinity. A high percentage of antagonistic fluorescent strains similar to Pseudomonas putida group were detected for chitosan‐treated plants in Wardan area (sandy soil). ASA drastically decreased the count of the pathogen in soil, but was conducive to the pathogen in plant tissues. A remarkable increase in microbial (bacterial and fungal) soil and rhizosphere diversity as indicated by PCR‐DGGE analysis for bacterial 16S rRNA and fungal 18S rRNA was recorded. In Talia area (silty clay soil), the soil microbial community was more stable and was in general resistant to the disease where the soils were characterized by high electrical conductivity. SWE, yeast and ASA significantly increased crop production in Talia area only. 相似文献
57.
Two new species of the genus Corollospora, namely, C. anglusa sp. nov. with its anamorph Varicosporina anglusa sp. nov. and C. portsaidica sp. nov., which were isolated from the coast of the Mediterranean Sea in Egypt, are described in this article based on morphological
and molecular evidence. The two new species have one-septate ascospores. Corollospora anglusa resembles C. gracilis by having narrow one-septate hyaline ascospores; however, they differ in ascomata and ascospore dimensions and in pure culture
characteristics. Single-ascospore culture of C. anglusa produces the conidia of its anamorph, whereas an anamorph has not been reported for C. gracilis. Varicosporina anglusa differs from the other two known Varicosporina species by having conidial branches that are filamentous, rectangularly branched, hypha like, and disarticulated into two-
or one-celled fragments. Corollospora portsaidica is morphologically similar to C. cinnamomea, but the two species differ in the dimensions, shape, and ornamentation of the ascospores. The new Corollospora species were confirmed to be divergent from other similar Corollospora species based on phylogenetic analyses of partial sequences of the LSU rDNA region. 相似文献
58.
Heba Diab Masashi Ohira Mali Liu Ester Cobb Patricia M. Kane 《The Journal of biological chemistry》2009,284(20):13316-13325
Disassembly of the yeast V-ATPase into cytosolic V1 and membrane
V0 sectors inactivates MgATPase activity of the
V1-ATPase. This inactivation requires the V1 H subunit
(Parra, K. J., Keenan, K. L., and Kane, P. M. (2000) J. Biol. Chem.
275, 21761–21767), but its mechanism is not fully understood. The H
subunit has two domains. Interactions of each domain with V1 and
V0 subunits were identified by two-hybrid assay. The B subunit of
the V1 catalytic headgroup interacted with the H subunit N-terminal
domain (H-NT), and the C-terminal domain (H-CT) interacted with V1
subunits B, E (peripheral stalk), and D (central stalk), and the cytosolic
N-terminal domain of V0 subunit Vph1p. V1-ATPase
complexes from yeast expressing H-NT are partially inhibited, exhibiting 26%
the MgATPase activity of complexes with no H subunit. The H-CT domain does not
copurify with V1 when expressed in yeast, but the bacterially
expressed and purified H-CT domain inhibits MgATPase activity in V1
lacking H almost as well as the full-length H subunit. Binding of full-length
H subunit to V1 was more stable than binding of either H-NT or
H-CT, suggesting that both domains contribute to binding and inhibition.
Intact H and H-CT can bind to the expressed N-terminal domain of Vph1p, but
this fragment of Vph1p does not bind to V1 complexes containing
subunit H. We propose that upon disassembly, the H subunit undergoes a
conformational change that inhibits V1-ATPase activity and
precludes V0 interactions.V-ATPases are ubiquitous proton pumps responsible for compartment
acidification in all eukaryotic cells
(1,
2). These pumps couple
hydrolysis of cytosolic ATP to proton transport into the lysosome/vacuole,
endosomes, Golgi apparatus, clathrin-coated vesicles, and synaptic vesicles.
Through their role in organelle acidification, V-ATPases are linked to
cellular functions as diverse as protein sorting and targeting, zymogen
activation, cytosolic pH homeostasis, and resistance to multiple types of
stress (3). They are also
recruited to the plasma membrane of certain cells, where they catalyze proton
export (4,
5).V-ATPases are evolutionarily related to ATP synthases of bacteria and
mitochondria and consist of two multisubunit complexes, V1 and
V0, which contain the sites for ATP hydrolysis and proton
transport, respectively. Like the ATP synthase (F-ATPase), V-ATPases utilize a
rotational catalytic mechanism. ATP binding and hydrolysis in the three
catalytic subunits of the V1 sector generate sequential
conformational changes that drive rotation of a central stalk
(6–8).
The central stalk subunits are connected to a ring of proteolipid subunits in
the V0 sector that bind protons to be transported. The actual
transport is believed to occur at the interface of the proteolipids and
V0 subunit a. Rotational catalysis will be productive in proton
transport only if V0 subunit a is held stationary, whereas the
proteolipid ring rotates (8).
This “stator function” resides in a single peripheral stalk in
F-ATPases (9,
10), but is distributed among
up to three peripheral stalks in V-ATPases
(11–13).
The peripheral stator stalks link V0 subunit a to the catalytic
headgroup and ensures that there is rotation of the central stalk complex
relative to the V0 a subunit and catalytic headgroup.Eukaryotic V-ATPases are highly conserved in both their overall structure
and the sequences of individual subunits. Although homologs of most subunits
of eukaryotic V-ATPases are present in archaebacterial V-ATPases (also known
as A-ATPases), the C and H subunits are unique to eukaryotes. Both subunits
have been localized at the interface of the V1 and V0
sectors, suggesting that they are positioned to play a critical role in
structural and functional interaction between the two sectors
(14–16).
The yeast C and H subunits are the only eukaryotic V-ATPase subunits for which
x-ray crystal structures are available
(17,
18). The structure of the C
subunit revealed an elongated “dumbbell-shaped” molecule, with
foot, head, and neck domains
(18). The structure of the H
subunit indicated two domains. The N-terminal 348 amino acids fold into a
series of HEAT repeats and are connected by a 4-amino acid linker to a
C-terminal domain containing amino acids 352–478
(17). These two domains have
partially separable functions in the context of the assembled V-ATPase
(19). Complexes containing
only the N-terminal domain of the H subunit
(H-NT)2 supported some
ATP hydrolysis but little or no proton pumping in isolated vacuolar vesicles
(19,
20). The C-terminal domain
(H-CT) assembled with the rest of the V-ATPase in the absence of intact
subunit H, but supported neither ATPase nor proton pumping activity
(19). However, co-expression
of the H-NT and H-CT domains results in assembly of both sectors with the
V-ATPase and allows increased ATP-driven proton pumping in isolated vacuolar
vesicles. These results suggest that the H-NT and H-CT domains play distinct
and complementary roles even when the two domains are not covalently
attached.In addition to their role as dedicated proton pumps, eukaryotic V-ATPases
are also distinguished from F-ATPases and archaeal V-ATPases in their
regulation. Eukaryotic V-ATPases are regulated in part by reversible
disassembly of the V1 complex from the V0 complex
(1,
21,
22). In yeast, disassembly of
previously assembled complexes occurs in response to glucose deprivation, and
reassembly is rapidly induced by glucose readdition to glucose-deprived cells.
Disassembly down-regulates pump activity, and both the disassembled sectors
are inactivated. Inhibition of ATP hydrolysis in free V1 sectors is
particularly critical, because release of an active ATPase into the cytosol
could deplete cytosolic ATP stores. This inhibition is dependent in part on
the H subunit. V1 complexes isolated from vma13Δ
mutants, which lack the H subunit gene (V1(-H) complexes) have
MgATPase activity. Consistent with a physiological role for H subunit
inhibition of V1, heterozygous diploids containing elevated levels
of free V1 complexes without subunit H have severe growth defects
(23). V1 complexes
containing subunit H have no MgATPase activity, but retain some CaATPase
activity, suggesting a role for nucleotides in inhibition
(24,
25). Consistent with such a
role, both the CaATPase activity of native V1 and the MgATPase
activity of V1(-H) complexes are lost within a few minutes of
nucleotide addition (24).A number of points of interaction between the H subunit and the
V1 and V0 complexes have been identified through
two-hybrid assays, binding of expressed proteins, and cross-linking
experiments. These experiments have indicated that the H subunit binds to
V1 subunits E and G of the V-ATPase peripheral stalks
(26,
27), the catalytic subunit
(V1 subunit A)
(28), regulatory V1
subunit B (15), and the
N-terminal domain of subunit a
(28). Recently, Jeffries and
Forgac (29) have found that
cysteines introduced into the C-terminal domain of subunit H can be
cross-linked to subunit F in isolated V1 sectors via a 10-Å
cross-linking reagent.In this work, we examine both the subunit-subunit interactions and
functional roles of the H-NT and H-CT domains in inhibition of
V1-ATPase activity. When expressed in yeast cells lacking subunit
H, H-NT can be isolated with cytosolic V1 complexes, but H-CT
cannot. We find that both of these domains contribute to inhibition of ATPase
activity, but that stable binding to V1 and full inhibition of
activity requires both domains. We also find that the H-CT can bind to the
cytosolic N-terminal domain of V0 subunit Vph1p (Vph1-NT) in
isolation, but does not support tight binding of Vph1-NT to isolated
V1 complexes. 相似文献
59.
Spectrofluorometric determination of clonazepam in dosage forms: Application to content uniformity testing and human plasma
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The present paper describes a developed and validated simple, highly sensitive and cost‐effective spectrofluorometric method for determination of clonazepam (CNP). The proposed method depends on forming a highly fluorescent product through the reduction of CNP with Zn/HCl. The produced fluorophore exhibits a strong fluorescence at λem 350 nm after excitation at λex 250 nm. The use of carboxymethylcellulose (CMC) greatly enhanced the fluorescence intensity of the produced fluorophore to the extent of about 100%. Calibration curve showed good linear regression (r 2 > 0.9998) within test ranges of 20–400 ng ml?1 with a lower detection limit of 0.67 ng ml?1 and lower quantification limit of 2.22 ng ml?1 upon using CMC. The method was successfully applied to the analysis of CNP in its pharmaceutical formulations and the results were in agreement with those obtained using a reference method. Furthermore, the content uniformity testing of the tablets was also performed. The application of the proposed method was extended to determine CNP in spiked human plasma sample as a preliminary investigation and the results were satisfactory. 相似文献
60.