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71.
Aerobic and microaerobic diazotrophs possess numerous oxygen restriction strategies to protect nitrogenase from inactivation by oxygen without interfering with energy generation through oxidative phosphorylation. Protection by conformational change in nitrogenase was first detected and described in Azotobacter. This strategy once considerd unique for Azotobacter has been shown in this study to occur in Citrobacterfreundii (Braak) Werkman and Gillen and Klebsiella pneumoniae subspecies rhinoscleromatis (Trevisan) Migula also. However, in these enteric bacteria the entire enzyme is not protected probably due to the absence of any respiratory protection similar to that found in the aerobe, Azotobacter. 相似文献
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Wang A Xia Q Xie W Dumonceaux T Zou J Datla R Selvaraj G 《The Plant journal : for cell and molecular biology》2002,30(6):613-623
Bread wheat (hexaploid AABBDD genome; 16 billion basepairs) is a genetically complex, self-pollinating plant with bisexual flowers that produce short-lived pollen. Very little is known about the molecular biology of its gametophyte development despite a longstanding interest in hybrid seeds. We present here a comprehensive characterization of three apparently homeologous genes (TAA1a, TAA1b and TAA1c) and demonstrate their anther-specific biochemical function. These eight-exon genes, found at only one copy per haploid complement in this large genome, express specifically within the sporophytic tapetum cells. The presence of TAA1 mRNA and protein was evident only at specific stages of pollen development as the microspore wall thickened during the progression of free microspores into vacuolated-microspores. This temporal regulation matched the assembly of wall-impregnated sporopollenin, a phenylpropanoid-lipid polymer containing very long chain fatty alcohols (VLCFAlc), described in the literature. Our results establish that sporophytic genes contribute to the production of fatty alcohols: Transgenic expression of TAA1 afforded production of long/VLCFAlc in tobacco seeds (18 : 1; 20 : 1; 22 : 1; 24 : 0; 26 : 0) and in Escherichia coli (14 : 0; 16 : 0; 18 : 1), suggesting biochemical versatility of TAA1 with respect to cellular milieu and substrate spectrum. Pollen walls additionally contain fatty alcohols in the form of wax esters and other lipids, and some of these lipids are known to play a role in the highly specific sexual interactions at the pollen-pistil interface. This study provides a handle to study these and to manipulate pollen traits, and, furthermore, to understand the molecular biology of fatty alcohol metabolism in general. 相似文献
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Synthesis,Characterization, and Biological Activities of Pendant Arm‐Pyridyltetrazole Copper(II) Complexes: DNA Binding/Cleavage Activity and Cytotoxic Studies 下载免费PDF全文
Shaik Mustafa Bommuluri Umamaheswara Rao Manubolu Surya Surendrababu Kalidindi Krishnam Raju Gollapalli Nageswara Rao 《化学与生物多样性》2015,12(10):1516-1534
2‐(1H‐Tetrazol‐5‐yl)pyridine ( L ) has been reacted separately with Me2NCH2CH2Cl?HCl and ClCH2CH2OH to yield two regioisomers in each case, N,N‐dimethyl‐2‐[5‐(pyridin‐2‐yl)‐1H‐tetrazol‐1‐yl]ethanamine ( L1 )/N,N‐dimethyl‐2‐[5‐(pyridin‐2‐yl)‐2H‐tetrazol‐2‐yl]ethanamine ( L2 ) and 2‐[5‐(pyridin‐2‐yl)‐1H‐tetrazol‐1‐yl]ethanol ( L3 )/2‐[5‐(pyridin‐2‐yl)‐2H‐tetrazol‐2‐yl]ethanol ( L4 ), respectively. These ligands, L1 – L4 , have been coordinated with CuCl2?H2O in 1 : 1 composition to furnish the corresponding complexes 1 – 4 . EPR Spectra of Cu complexes 1 and 3 were characteristic of square planar geometry, with nuclear hyperfine spin 3/2. Single X‐ray crystallographic studies of 3 revealed that the Cu center has a square planar structure. DNA binding studies were carried out by UV/VIS absorption; viscosity and thermal denaturation studies revealed that each of these complexes are avid binders of calf thymus DNA. Investigation of nucleolytic cleavage activities of the complexes was carried out on double‐stranded pBR322 circular plasmid DNA by using a gel electrophoresis experiment under various conditions, where cleavage of DNA takes place by oxidative free‐radical mechanism (OH ? ). In vitro anticancer activities of the complexes against MCF‐7 (human breast adenocarcinoma) cells revealed that the complexes inhibit the growth of cancer cells. The IC50 values of the complexes showed that Cu complexes exhibit comparable cytotoxic activities compared to the standard drug cisplatin. 相似文献
77.
Divakara S. S. M. Uppu Goutham B. Manjunath Venkateswarlu Yarlagadda Jyothi E. Kaviyil Raju Ravikumar Krishnamoorthy Paramanandham Bibek R. Shome Jayanta Haldar 《PloS one》2015,10(3)
Gram-negative ‘superbugs’ such as New Delhi metallo-beta-lactamase-1 (bla
NDM-1) producing pathogens have become world’s major public health threats. Development of molecular strategies that can rehabilitate the ‘old antibiotics’ and halt the antibiotic resistance is a promising approach to target them. We report membrane-active macromolecules (MAMs) that restore the antibacterial efficacy (enhancement by >80-1250 fold) of tetracycline antibiotics towards bla
NDM-1
Klebsiella pneumonia and bla
NDM-1
Escherichia coli clinical isolates. Organismic studies showed that bacteria had an increased and faster uptake of tetracycline in the presence of MAMs which is attributed to the mechanism of re-sensitization. Moreover, bacteria did not develop resistance to MAMs and MAMs stalled the development of bacterial resistance to tetracycline. MAMs displayed membrane-active properties such as dissipation of membrane potential and membrane-permeabilization that enabled higher uptake of tetracycline in bacteria. In-vivo toxicity studies displayed good safety profiles and preliminary in-vivo antibacterial efficacy studies showed that mice treated with MAMs in combination with antibiotics had significantly decreased bacterial burden compared to the untreated mice. This report of re-instating the efficacy of the antibiotics towards bla
NDM-1 pathogens using membrane-active molecules advocates their potential for synergistic co-delivery of antibiotics to combat Gram-negative superbugs. 相似文献
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Joseph C. Y. Liu Janice M. Leung David A. Ngan Negar F. Nashta Silvia Guillemi Marianne Harris Viviane D. Lima Soo-Jung Um Yuexin Li Sheena Tam Tawimas Shaipanich Rekha Raju Cameron Hague Jonathon A. Leipsic Jean Bourbeau Wan C. Tan P. Richard Harrigan Don D. Sin Julio Montaner S. F. Paul Man 《PloS one》2015,10(4)
Combination antiretroviral therapy (cART) has extended the longevity of human immunodeficiency virus (HIV)-infected individuals. However, this has resulted in greater awareness of age-associated diseases such as chronic obstructive pulmonary disease (COPD). Accelerated cellular senescence may be responsible, but its magnitude as measured by leukocyte telomere length is unknown and its relationship to HIV-associated COPD has not yet been established. We measured absolute telomere length (aTL) in peripheral leukocytes from 231 HIV-infected adults. Comparisons were made to 691 HIV-uninfected individuals from a population-based sample. Subject quartiles of aTL were assessed for relationships with measures of HIV disease severity, airflow obstruction, and emphysema severity on computed tomographic (CT) imaging. Multivariable regression models identified factors associated with shortened aTL. Compared to HIV-uninfected subjects, the mean aTL in HIV-infected patients was markedly shorter by 27 kbp/genome (p<0.001); however, the slopes of aTL vs. age were not different (p=0.469). Patients with longer known durations of HIV infection (p=0.019) and lower nadir CD4 cell counts (p=0.023) had shorter aTL. Shorter aTL were also associated with older age (p=0.026), smoking (p=0.005), reduced forced expiratory volume in one second (p=0.030), and worse CT emphysema severity score (p=0.049). HIV-infected subjects demonstrate advanced cellular aging, yet in a cART-treated cohort, the relationship between aTL and age appears no different from that of HIV-uninfected subjects. 相似文献
80.
Raju V. S. Rajala 《Molecular neurobiology》2010,42(1):39-47
The retina is an integral part of the central nervous system and retinal cells are known to express insulin receptors (IR),
although their function is not known. This article describes recent studies that link the photoactivation of rhodopsin to
tyrosine phosphorylation of the IR and subsequent activation of phosphoinositide 3-kinase, a neuron survival factor. Our studies
suggest that the physiological role of this process is to provide neuroprotection of the retina against light damage by activating
proteins that protect against stress-induced apoptosis. We focus mainly on our recently identified regulation of the IR pathway
through the G-protein-coupled receptor rhodopsin. Various mutant and knockout proteins of phototransduction cascade have been
used to study the light-induced activation of the retinal IR. Our studies suggest that rhodopsin may have additional previously
uncharacterized signaling functions in photoreceptors. 相似文献