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排序方式: 共有218条查询结果,搜索用时 312 毫秒
1.
Aamir Hamid Khan Ling Min Yizan Ma Muhammad Zeeshan Shuangxia Jin Xianlong Zhang 《Plant biotechnology journal》2023,21(4):680-697
Global food security is one of the utmost essential challenges in the 21st century in providing enough food for the growing population while coping with the already stressed environment. High temperature (HT) is one of the main factors affecting plant growth, development and reproduction and causes male sterility in plants. In male reproductive tissues, metabolic changes induced by HT involve carbohydrates, lipids, hormones, epigenetics and reactive oxygen species, leading to male sterility and ultimately reducing yield. Understanding the mechanism and genes involved in these pathways during the HT stress response will provide a new path to improve crops by using molecular breeding and biotechnological approaches. Moreover, this review provides insight into male sterility and integrates this with suggested strategies to enhance crop tolerance under HT stress conditions at the reproductive stage. 相似文献
2.
Amir Hamza Khan Dr. Said Hassan Muhammad Aamir Dr. Muhammad Waseem Khan Dr. Fazal Haq Junaid Hayat Dr. Muhammad Rizwan Dr. Amin Ullah Izzat Ullah Dr. Gokhan Zengin Dr. Arshad Farid 《化学与生物多样性》2023,20(10):e202301068
The current study was designed to evaluate the antioxidant, anticancer and antimicrobial activities of silver nanoparticles (AgNPs) biosynthesized by Spirulina platensis extract. The biosynthesized silver nanoparticles were characterized using Fourier transform infrared (FT-IR) analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis. The antioxidant activity of the biosynthesized AgNPs were determined via DPPH radical scavenging assay while its anticancer activity was determined using the MTT assay. The antimicrobial activity of the biosynthesized AgNPs were analyzed by disc diffusion method. Spirulina platensis acts as a reducing and capping agent. The efficacy of silver nanoparticles (AgNPs) in inhibiting the growth of Gram-negative bacteria, specifically Acetobacter, Klebsiella, Proteus vulgaris, and Pseudomonas aeruginosa, was assessed by the utilisation of the diffusion method. The study aimed to evaluate the efficacy of biosynthesized silver nanoparticles (AgNPs) against many strains of Pseudomonas aeruginosa bacteria. The findings of the study revealed that when administered in doses of 50 μl, 75 μl, and 100 μl, the largest observed zone of inhibition corresponded to measurements of 10.5 mm, 14 mm, and 16 mm, respectively. A zone of inhibition with dimensions of 8 mm, 10.5 mm, and 12 mm was detected during testing against Acetobacter at concentrations of 50 μl, 75 μl, and 100 μl, respectively. The findings also indicate that there is a positive correlation between the concentration of AgNP and the DPPH scavenging ability of silver nanoparticles. The percentage of inhibition observed at concentrations of 500 μg/ml, 400 μg/ml, 300 μg/ml, 200 μg/ml, and 100 μg/ml were recorded as 80±1.98, 61±1.98, 52±1.5, 42±1.99, and 36±1.97, respectively. In addition, it was observed that the silver nanoparticles exhibited the greatest antioxidant activity at a concentration of 500 g/ml, with a measured value of 80.89±1.99. The IC-50 values, representing the inhibitory concentration required to achieve 50 % inhibition, were found to be 8.16, 19.15, 30.14, 41.13, and 63.11 at inhibition levels of 36±1.97, 42±1.99, 52±1.5, 61±1.98, and 80±1.98, respectively. 相似文献
3.
Culture supernatants of murine thymocytes or spleen cells responding in a secondary syngeneic mixed leukocyte reaction (SMLR) were studied for their biologic effects on cell-mediated immune responses in vitro. Such supernatants contained helper factor(s) that facilitated the development of alloantigen-specific cytotoxic T lymphocyte (CTL) responses from thymocyte precursors. Thymocytes, but not spleen cells, required activation by allogeneic effect factor (AEF) in primary culture in order to proliferate and produce biologically active mediator(s) during a secondary SMLR. The same culture supernatants possessed, in some instances, weak T cell growth factor (TCGF; IL 2) activity. However, TCGF activity could be dissociated from helper factor(s) active in the CTL induction assay because some culture supernatants that had potent helper activity were devoid of TCGF activity. This lack of TCGF activity was not due to a lower degree of sensitivity of the TCGF assay or to the presence of a selective TCGF inhibitor in the SMLR-derived supernatants, indicating that the helper factor(s) studied is distinct from TCGF. Production of immunoregulatory lymphokines during the SMLR may serve as a physiologically relevant model for studying the role of T cell-derived lymphokines in immunoregulation. 相似文献
4.
Nucleotide sequence and characterization of a Bacillus subtilis gene encoding a flagellar switch protein. 总被引:11,自引:8,他引:3 下载免费PDF全文
The nucleotide sequence of the Bacillus subtilis fliM gene has been determined. This gene encodes a 38-kDa protein that is homologous to the FliM flagellar switch proteins of Escherichia coli and Salmonella typhimurium. Expression of this gene in Che+ cells of E. coli and B. subtilis interferes with normal chemotaxis. The nature of the chemotaxis defect is dependent upon the host used. In B. subtilis, overproduction of FliM generates mostly nonmotile cells. Those cells that are motile switch less frequently. Expression of B. subtilis FliM in E. coli also generates nonmotile cells. However, those cells that are motile have a tumble bias. The B. subtilis fliM gene cannot complement an E. coli fliM mutant. A frameshift mutation was constructed in the fliM gene, and the mutation was transferred onto the B. subtilis chromosome. The mutant has a Fla- phenotype. This phenotype is consistent with the hypothesis that the FliM protein encodes a component of the flagellar switch in B. subtilis. Additional characterization of the fliM mutant suggests that the hag and mot loci are not expressed. These loci are regulated by the SigD form of RNA polymerase. We also did not observe any methyl-accepting chemotaxis proteins in an in vivo methylation experiment. The expression of these proteins is also dependent upon SigD. It is possible that a functional basal body-hook complex may be required for the expression of SigD-regulated chemotaxis and motility genes. 相似文献
5.
Biochemical and biophysical characterization of human recombinant IgE-binding protein, an S-type animal lectin. 总被引:4,自引:0,他引:4
IgE-binding protein (epsilon BP) was originally identified by virtue of its affinity for IgE. It is now known to be a beta-galactoside-binding lectin with the characteristic of an S-type carbohydrate recognition domain. The protein is composed of two domains: the amino-terminal domain consisting of tandem repeats and the carboxyl-terminal domain containing sequences shared by other S-type carbohydrate recognition domains. The amino-terminal domain also contains a number of potential recognition sites for collagenase cleavage. In this study, human epsilon BP was first expressed in Escherichia coli, and the carboxyl-terminal domain (epsilon BP-C) was then generated by collagenase digestion of epsilon BP. By equilibrium dialysis, the association constants of epsilon BP and epsilon BP-C for lactose were found to be similar (6.0 +/- 0.70) x 10(4) M-1 and (4.7 +/- 0.27) x 10(4) M-1, respectively. Both polypeptides contain only one lactose-binding site/molecule. By an assay involving binding of 125I-labeled epsilon BP or epsilon BP-C to solid phase IgE, and inhibition of this binding by saccharides, it was determined that epsilon BP-C retains the saccharide specificity of epsilon BP. Importantly, although unlabeled epsilon BP-C inhibited the binding of the radiolabeled epsilon BP to IgE, unlabeled epsilon BP caused increased binding to IgE, suggesting self-association among epsilon BP molecules. Oligomeric structures resulting from self-association of epsilon BP were confirmed by chemical cross-linking studies. Furthermore, epsilon BP possesses hemagglutination activity on rabbit erythrocytes, whereas epsilon BP-C lacks such activity. Based on these results, we propose a structural model for multivalency of epsilon BP: dimerization or oligomerization of epsilon BP occurs through intermolecular interaction involving the amino-terminal domain. 相似文献
6.
7.
Md. Ashraful Alam Milan Skalicky Muhammad Rezaul Kabir Md. Monwar Hossain Md. Abdul Hakim Md. Siddikun Nabi Mandal Rabiul Islam Md. Babul Anwar Akbar Hossain Fahmy Hassan Amaal Mohammadein Muhammad Aamir Iqbal Marian Brestic Mohammad Anwar Hossain Khalid Rehman Hakeem Ayman EL Sabagh 《Phyton》2021,90(4):1301-1320
Globally among biotic stresses, diseases like blight, rust and blast constitute prime constraints for reducing wheat
productivity especially in Bangladesh. For sustainable productivity, the development of disease-resistant lines and
high yielding varieties is vital and necessary. This study was conducted using 122 advanced breeding lines of
wheat including 21 varieties developed by Bangladesh Wheat and Maize Research Institute (BAMRI) with aims
to identify genotypes having high yield potential and resistance to leaf blight, leaf rust and blast diseases. These
genotypes were evaluated for resistance against leaf blight and leaf rust at Dinajpur and wheat blast at Jashore
under field condition. Out of 122 genotypes tested, 20 lines were selected as resistant to leaf blight based on
the area under the diseases progress curve (AUDPC) under both irrigated timely sown (ITS) and irrigated late
sown (ILS) conditions. Forty-two genotypes were found completely free from leaf rust infection, 59 genotypes
were identified as resistant, and 13 genotypes were identified as moderately resistant to leaf rust. Eighteen genotypes were immune against wheat blast, 42 genotypes were categorized as resistant, and 26 genotypes were identified as moderately resistant to wheat blast. Molecular data revealed that the 16 genotypes showed a positive 2NS
segment among the 18 immune genotypes selected against wheat blast under field conditions. The genotypes
BAW 1322, BAW 1295, and BAW 1203 can be used as earlier maturing genotypes and the genotypes BAW
1372, BAW 1373, BAW 1297 and BAW 1364 can be used for lodging tolerant due to short plant height. The genotypes WMRI Gom 1, BAW 1349 and BAW 1350 can be selected for bold grain and the genotypes WMRI Gom 1,
BAW 1297, BAW 1377 can be used as high yielder for optimum seeding condition but genotypes BAW 1377
and BAW 1366 can be used for late sown condition. The selected resistant genotypes against specific diseases can be used in the further breeding program to develop wheat varieties having higher disease resistance and
yield potential. 相似文献
8.
M. F. Ullah Aamir Ahmad Husain Y. Khan H. Zubair Fazlul H. Sarkar S. M. Hadi 《Cell biochemistry and biophysics》2013,67(2):431-438
Plant-derived dietary antioxidants have attracted considerable interest in recent past for their ability to induce apoptosis and regression of tumors in animal models. While it is believed that the antioxidant properties of these agents may contribute to lowering the risk of cancer induction by impeding oxidative injury to DNA, it could not account for apoptosis induction and chemotherapeutic observations. In this article, we show that dietary antioxidants can alternatively switch to a prooxidant action in the presence of transition metals such as copper. Such a prooxidant action leads to strand breaks in cellular DNA and growth inhibition in cancer cells. Further, the cellular DNA breakage and anticancer effects were found to be significantly enhanced in the presence of copper ions. Moreover, inhibition of antioxidant-induced DNA strand breaks and oxidative stress by Cu(I)-specific chelators bathocuproine and neocuproine demonstrated the role of endogenous copper in the induction of the prooxidant mechanism. Since it is well established that tissue, cellular, and serum copper levels are considerably elevated in various malignancies, such a prooxidant cytotoxic mechanism better explains the anticancer activity of dietary antioxidants against cancer cells. 相似文献
9.
Heat shock protein induction is often associated with a cellular response to a harmful environment or to adverse life conditions. The main aims of our study were (1) to evaluate the cytotoxic potential of cypermethrin; and (2) to investigate the suitability of stress-induced heat shock protein Hsp70 as a biomarker for environmental pollutants in transgenic Drosophila melanogaster (Hsp70-lacZ)Bg9. Different concentrations of cypermethrin (0.002, 0.2, 0.5 and 50.0 p.p.m.) were mixed with food. Third instar larvae of transgenic Drosophila melanogaster were allowed to feed on these mixtures for different time intervals (2, 4, 6, 12, 24 and 48h). Following feeding, hsp70 induction and tissue damage were evaluated. In the highest concentration treatment group (50 p.p.m.), 100% larval mortality was recorded after 12 h exposure. Hsp70 was found to be induced even at the lowest concentration (0.002 p.p.m.) of the insecticide, while tissue damage was observed in the larvae exposed for 48 h. While an insignificant decline in hsp70 expression was observed in the larvae exposed to cypermethrin at a dietary concentration of 0.002 p.p.m. after 48 h compared with those exposed for 24 h, in the next two higher concentrations of the toxicant, a similar but significant decline in hsp70 expression was evident in the exposed larvae after 48 h. The present study reveals the cytotoxic potential of cypermethrin and further proposes that hsp70 induction in transgenic Drosophila melanogaster could be used as a sensitive biomarker in risk assessment. 相似文献
10.
Nazish Badar Uzma Bashir Aamir Muhammad Rashid Mehmood Nadia Nisar Muhammad Masroor Alam Birjees Mazhar Kazi Syed Sohail Zahoor Zaidi 《PloS one》2013,8(11)