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1.
The mitotic spindle is a microtubule (MT)-based molecular machine that serves for equal segregation of chromosomes during cell division. The formation of the mitotic spindle requires the activity of MT motors, including members of the kinesin-14 family. Although evidence suggests that kinesins-14 act by driving the sliding of MT bundles in different areas of the spindle, such sliding activity had never been demonstrated directly. To test the hypothesis that kinesins-14 can induce MT sliding in living cells, we developed an in vivo assay, which involves overexpression of the kinesin-14 family member Drosophila Ncd in interphase mammalian fibroblasts. We found that green fluorescent protein (GFP)-Ncd colocalized with cytoplasmic MTs, whose distribution was determined by microinjection of Cy3 tubulin into GFP-transfected cells. Ncd overexpression resulted in the formation of MT bundles that exhibited dynamic "looping" behavior never observed in control cells. Photobleaching studies and fluorescence speckle microscopy analysis demonstrated that neighboring MTs in bundles could slide against each other with velocities of 0.1 microm/s, corresponding to the velocities of movement of the recombinant Ncd in in vitro motility assays. Our data, for the first time, demonstrate generation of sliding forces between adjacent MTs by Ncd, and they confirm the proposed roles of kinesins-14 in the mitotic spindle morphogenesis. 相似文献
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Modulation of intracellular Ca2+ release and capacitative Ca2+ entry by CaMKII inhibitors in bovine vascular endothelial cells 总被引:2,自引:0,他引:2
The effects of inhibitors of CaMKII on intracellular Ca2+ signaling were examined in single calf pulmonary artery endothelial (CPAE) cells using indo-1 microfluorometry to measure cytoplasmic Ca2+ concentration ([Ca2+]i). The three CaMKII inhibitors, KN-93, KN-62, and autocamtide-2-related inhibitory peptide (AIP), all reduced the plateau phase of the [Ca2+]i transient evoked by stimulation with extracellular ATP. Exposure to KN-93 or AIP alone in the presence of 2 mM extracellular Ca2+ resulted in a dose-dependent increase of [Ca2+]i consisting of a rapid and transient Ca2+ spike followed by a small sustained plateau phase of elevated [Ca2+]i. Exposure to KN-93 in the absence of extracellular Ca2+ caused a transient rise of [Ca2+]i, suggesting that exposure to CaMKII inhibitors directly triggered release of Ca2+ from intracellular endoplasmic reticulum (ER) Ca2+ stores. Repetitive stimulation with KN-93 and ATP, respectively, revealed that both components released Ca2+ largely from the same store. Pretreatment of CPAE cells with the membrane-permeable inositol 1,4,5-trisphosphate (IP3) receptor blocker 2-aminoethoxydiphenyl borate caused a significant inhibition of the KN-93-induced Ca2+ response, suggesting that exposure to KN-93 affects Ca2+ release from an IP3-sensitive store. Depletion of Ca2+ stores by exposure to ATP or to the ER Ca2+ pump inhibitor thapsigargin triggered robust capacitative Ca2+ entry (CCE) signals in CPAE cells that could be blocked effectively with KN-93. The data suggest that in CPAE cells, CaMKII modulates Ca2+ handling at different levels. The use of CaMKII inhibitors revealed that in CPAE cells, the most profound effects of CaMKII are inhibition of release of Ca2+ from intracellular stores and activation of CCE. Ca2+/calmodulin-dependent kinase II; calcium regulation; capacitative calcium entry 相似文献
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DNA barcoding of economically important freshwater fish species from north‐central Nigeria uncovers cryptic diversity
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Moshood K. Mustapha Chioma G. Nzeh Segun O. Oladipo Ifeanyi C. Nneji Agboola O. Okeyoyin Christopher D. Nwani Obih A. Ugwumba Adiaha A. A. Ugwumba Emmanuel O. Faturoti Yun‐yu Wang Jing Chen Wen‐Zhi Wang Adeniyi C. Adeola 《Ecology and evolution》2018,8(14):6932-6951
This study examines the utility of morphology and DNA barcoding in species identification of freshwater fishes from north‐central Nigeria. We compared molecular data (mitochondrial cytochrome c oxidase subunit I (COI) sequences) of 136 de novo samples from 53 morphologically identified species alongside others in GenBank and BOLD databases. Using DNA sequence similarity‐based (≥97% cutoff) identification technique, 50 (94.30%) and 24 (45.30%) species were identified to species level using GenBank and BOLD databases, respectively. Furthermore, we identified cases of taxonomic problems in 26 (49.00%) morphologically identified species. There were also four (7.10%) cases of mismatch in DNA barcoding in which our query sequence in GenBank and BOLD showed a sequence match with different species names. Using DNA barcode reference data, we also identified four unknown fish samples collected from fishermen to species level. Our Neighbor‐joining (NJ) tree analysis recovers several intraspecific species clusters with strong bootstrap support (≥95%). Analysis uncovers two well‐supported lineages within Schilbe intermedius. The Bayesian phylogenetic analyses of Nigerian S. intermedius with others from GenBank recover four lineages. Evidence of genetic structuring is consistent with geographic regions of sub‐Saharan Africa. Thus, cryptic lineage diversity may illustrate species’ adaptive responses to local environmental conditions. Finally, our study underscores the importance of incorporating morphology and DNA barcoding in species identification. Although developing a complete DNA barcode reference library for Nigerian ichthyofauna will facilitate species identification and diversity studies, taxonomic revisions of DNA sequences submitted in databases alongside voucher specimens are necessary for a reliable taxonomic and diversity inventory. 相似文献
5.
Coexistence of Aflatoxicosis with Protein Malnutrition Worsens Hepatic Oxidative Damage in Rats
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Oluwakemi A. Rotimi Solomon O. Rotimi Flora Oluwafemi Oladipo Ademuyiwa Elizabeth A. Balogun 《Journal of biochemical and molecular toxicology》2016,30(6):269-276
To investigate the effects of the coexistence of aflatoxin B1 (AFB1) and protein malnutrition in rat liver, weanling rats were fed either normal protein diet (20% protein), low‐protein (PEM) diet (5%), normal protein diet + 40 ppb AFB1, or low‐protein diet + 40 ppb AFB1. After 8 weeks, biomarkers of hepatic functions and oxidative stress, caspase‐3 activity, and tumor suppressor protein 53 (p53) were determined spectrophotometrically. Randomly amplified polymorphic DNA polymerase chain reaction (RAPD‐PCR) was employed to determine genomic alterations among the groups. Coexistence of aflatoxicosis and PEM significantly decreased glutathione, glutathione‐S‐transferase, glutathione peroxidase, and superoxide dismutase, while it increased peroxidase and catalase. RAPD‐PCR showed genomic alterations that were associated with significant increases in p53 level and caspase‐3 activity in rats fed PEM diet + AFB1. In conclusion, the coexistence of aflatoxicosis and protein malnutrition induced oxidative stress with concomitant genomic alterations in the liver of weanling rats. 相似文献
6.
Eric T. Sumrall Elizabeth B. Gallo Aaron Oladipo Aboderin Adebayo Lamikanra Iruka N. Okeke 《PloS one》2014,9(10)
The plasmid-encoded quinolone resistance gene qnrS1 was recently found to be commonly associated with ciprofloxacin resistance in Nigeria. We mapped the qnrS1 gene from an Escherichia coli isolate obtained in Nigeria to a 43.5 Kb IncX2 plasmid. The plasmid, pEBG1, was sufficient to confer ciprofloxacin non-susceptibility, as well as tetracycline and trimethoprim resistance, on E. coli K-12. Deletion analysis confirmed that qnrS1 accounted for all the ciprofloxacin non-suceptibility conferred by pEBG1 and tetracycline and trimethoprim resistance could be attributed to tetAR and dfrA14 genes respectively. While it contained a complete IncX conjugation system, pEBG1 was not self-transmissible likely due to an IS3 element inserted between the pilX5 and pilX6 genes. The plasmid was however efficiently mobilizable. pEBG1 was most similar to another qnrS1-bearing IncX2 plasmid from Nigeria, but both plasmids acquired qnrS1 independently and differ in their content of other resistance genes. Screening qnrS1–positive isolates from other individuals in Nigeria revealed that they carried neither pEBG1 nor pNGX2-QnrS1 but that IncX plasmids were prevalent. This study demonstrates that the IncX backbone is a flexible platform that has contributed to qnrS1 dissemination in Nigeria. 相似文献
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Segun O. Oladipo Lotanna M. Nneji Abass T. Anifowoshe Ifeanyi C. Nneji 《Journal of fish biology》2020,97(6):1865-1869
Molecular (mitochondrial cytochrome C oxidase subunit 1– COI) analysis was performed to characterize the poorly known Malapterurus minjiriya from Nigerian inland water bodies. Integrative taxonomy, involving morphological and molecular data, confirms the identity of M. minjiriya. Matrilineal genealogy reveals a sister relationship of M. minjiriya with Malapterurus electricus and Malapterurus microstoma. The genetic analysis further shows evidence of population divergence within M. electricus and Malapterurus beninensis. The findings of the study highlight the importance of the integration of DNA barcoding in biodiversity documentation of freshwater fish species in Nigeria. 相似文献
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Oluwatosin Gbemisola Oladipo Olusegun Olufemi Awotoye Akin Olayinka Obinna Tobechukwu Ezeokoli Mark Steve Maboeta Cornelius Carlos Bezuidenhout 《Bioremediation Journal》2016,20(4):287-297
Increased heavy metal pollution generated through anthropogenic activities into the environment has necessitated the need for eco-friendly remediation strategies such as mycoremediation. With a view to prospecting for fungi with heavy metal remediation potentials, the tolerance of five Aspergillus species isolated from soils of three active gold and gemstone mining sites in southwestern Nigeria to varied heavy metal concentrations was investigated. Isolated Aspergillus strains were identified based on the internal transcribed spacer 1 and 2 (ITS 1 and ITS 2) regions. Growth of Aspergillus strains were challenged with a range of varied concentrations of heavy metals: cadmium (Cd) (0–100), copper (Cu) (0–1000), lead (Pb) (0–400), arsenic (As) (0–500), and iron (Fe) (0–800) concentrations (ppm) incorporated into Malt Extract Agar (MEA) in triplicates. Mycelial radial growths were recorded at intervals of 3 days during a 13-day incubation period. Aspergillus strains were identified as A. tubingensis, A. fumigatus, A. terreus, A. nidulans, and A. nomius. A. tubingensis tolerated Cd, Cu, Pb, As, and Fe at all test concentrations (100–1000 ppm), showing no significant (p > .05) difference compared with the control. Similarly, A. nomius tolerated all concentrations of Cu, Pb, As, and Fe and only 50 ppm Cd concentrations. A. nidulans, A. terreus, and A. fumigatus, on the other hand, tolerated all concentrations of Cu, Pb, and Fe with no statistical significance (p > .05) difference from the controls. Overall, the Aspergillus species showed tolerance to heavy metal concentrations above permissible limits for contaminated soils globally. These heavy metal tolerance traits exhibited by the Aspergillus isolates may suggest that they are potential candidates for bioremediation of heavy metal–polluted environments. 相似文献
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O.A. Ojo S.O. Oladipo K.A. Odelade 《Archives Of Phytopathology And Plant Protection》2013,46(20):2421-2428
The ethanolic extracts of Cybopogon flexuosus and Ageratum conyzoides were tested at concentrations of 20, 40, 60, 80, 100 and 120?mg/ml for their in vitro fungicidal activities against five phytopathogenic fungi isolated from diseased watermelon fruits. The pathogens were Fusarium verticillioides, Aspergillus flavus, Botryodiplodia theobromae, Curvularia lunata and Alternaria cucumeria – Amans as confirmed by pathogenicity tests. All isolated pathogenic fungi were significantly (p?≥?0.05) highly pathogenic with the exception of A. cucumeria which had the least significant (p?≥?0.05) pathogenicity. The inhibitory effects of the extracts increased significantly (p?≥?0.05) with increase in concentrations. Some of the concentrations reduced the mycelial growth of the pathogens to a significant (p?≥?0.05) level. Very strong fungicidal activity was produced by extracts of A. conyzoides at 100?mg/ml against all the fungi. The inhibitory effects of C. flexuosus extracts at 20, 40 and 60?mg/ml were greater than those of C. flexuosus on A. flavus, F. verticillioides and A. cucumeria. The results of the investigation indicated that plant extracts possess antifungal activity that can be exploited as an ideal treatment for future plant disease management in the control of rot of water melon. 相似文献
10.
Nneji Lotanna Micah Adeola Adeniyi Charles Ayoola Adeola Oluwakemi Oladipo Segun Olayinka Wang Yun-Yu Malann Yoila D. Anyaele Okorie Nneji Ifeanyi Christopher Rahman Md Mizanur Olory Caroline Samuel 《Molecular biology reports》2020,47(12):9441-9457
Molecular Biology Reports - Accurate identification of species is a prerequisite for successful biodiversity management and further genetic studies. Species identification techniques often require... 相似文献