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  • Life Sciences (General)  (3)
  • Key words Arbuscular mycorrhizal fungi  (1)
  • 1
    ISSN: 1432-1890
    Keywords: Key words Arbuscular mycorrhizal fungi ; Internal transcribed spacer ; Ribosomal DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The 5.8 S subunit and flanking internal transcribed spacer (ITS) regions in nuclear ribosomal DNA (rDNA) from spores of Glomus mosseae FL156 and UK118 were amplified by polymerase chain reaction (PCR) using ITS1 and ITS4 as primers. The amplification product from template DNA of UK118 was cloned and sequenced (569 bp); the amplified DNA from FL156 was sequenced directly (582 bp). There was a 95% sequence similarity between DNAs amplified from the two isolates; in contrast, major dissimilarities with partial sequences of seven other glomalean taxa were observed. Four oligonucleotide sequences unique to Glomus mosseae were identified as potential primers. Their specificity to Glomus mosseae was assessed by PCR amplification of genomic DNA from spores from 36 glomalean fungi: 13 isolates of Glomus mosseae, two Glomus monosporum, 10 other Glomus isolates, and 11 other glomalean taxa from each of four other genera. The Glomus mosseae isolates were from a broad range of temperate zone agricultural soils. Oligonucleotide pair GMOS1 : GMOS2 primed specific amplification of an oligonucleotide sequence (approximately 400 bp) present in all Glomus mosseae isolates and two isolates of the closely related Glomus monosporum. This primer pair did not prime PCR when the template consisted of DNA from any of the other glomalean fungi or any of the nonmycorrhizal controls. In addition, a 24-mer oligonucleotide, designated GMOS5, hybridized with Glomus mosseae and Glomus monosporum DNA amplified by PCR using primer pairs ITS1 : ITS4 and GMOS1 : GMOS2. Colony-blot assays showed that GMOS5 hybridized to 100% and 97% of E. coli pUC19 clones of amplification products from Glomus mosseae FL156 and UK118 DNA templates, respectively, indicating that nearly all clones contained an homologous sequence. GMOS5 was used successfully to detect specifically Glomus mosseae in DNA extracted from colonized sudan grass (Sorghum sudanense L.) roots and amplified by PCR using the primer pair GMOS1 : GMOS2. The results confirm several previous indications that Glomus mosseae and Glomus monosporum are indistinguishable taxonomic entities.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2019-07-13
    Description: Cyclic strain regulates many vascular smooth muscle cell (VSMC) functions through changing gene expression. This study investigated the effects of cyclic strain on protease-activated receptor-1 (PAR-1) expression in VSMCs and the possible signaling pathways involved, on the basis of the hypothesis that cyclic strain would enhance PAR-1 expression, reflecting increased thrombin activity. Uniaxial cyclic strain (1 Hz, 20%) of cells cultured on elastic membranes induced a 2-fold increase in both PAR-1 mRNA and protein levels. Functional activity of PAR-1, as assessed by cell proliferation in response to thrombin, was also increased by cyclic strain. In addition, treatment of cells with antioxidants or an NADPH oxidase inhibitor blocked strain-induced PAR-1 expression. Preincubation of cells with protein kinase inhibitors (staurosporine or Ro 31-8220) enhanced strain-increased PAR-1 expression, whereas inhibitors of NO synthase, tyrosine kinase, and mitogen-activated protein kinases had no effect. Cyclic strain in the presence of basic fibroblast growth factor induced PAR-1 mRNA levels beyond the effect of cyclic strain alone, whereas no additive effect was observed between cyclic strain and platelet-derived growth factor-AB. Our findings that cyclic strain upregulates PAR-1 mRNA expression but that shear stress downregulates this gene in VSMCs provide an opportunity to elucidate signaling differences by which VSMCs respond to different mechanical forces.
    Keywords: Life Sciences (General)
    Type: Hypertension (ISSN 0194-911X); 38; 5; 1038-43
    Format: text
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  • 3
    Publication Date: 2019-07-13
    Description: Shear stress has been shown to regulate several genes involved in the thrombotic and proliferative functions of endothelial cells. Thrombin receptor (protease-activated receptor-1: PAR-1) increases at sites of vascular injury, which suggests an important role for PAR-1 in vascular diseases. However, the effect of shear stress on PAR-1 expression has not been previously studied. This work investigates effects of shear stress on PAR-1 gene expression in both human umbilical vein endothelial cells (HUVECs) and microvascular endothelial cells (HMECs). Cells were exposed to different shear stresses using a parallel plate flow system. Northern blot and flow cytometry analysis showed that shear stress down-regulated PAR-1 messenger RNA (mRNA) and protein levels in both HUVECs and HMECs but with different thresholds. Furthermore, shear-reduced PAR-1 mRNA was due to a decrease of transcription rate, not increased mRNA degradation. Postshear stress release of endothelin-1 in response to thrombin was reduced in HUVECs and HMECs. Moreover, inhibitors of potential signaling pathways applied during shear stress indicated mediation of the shear-decreased PAR-1 expression by protein kinases. In conclusion, shear stress exposure reduces PAR-1 gene expression in HMECs and HUVECs through a mechanism dependent in part on protein kinases, leading to altered endothelial cell functional responses to thrombin.
    Keywords: Life Sciences (General)
    Type: Annals of biomedical engineering (ISSN 0090-6964); 29; 2; 145-52
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  • 4
    Publication Date: 2019-07-13
    Description: Recent studies have demonstrated that vascular smooth muscle cells are responsive to changes in their local hemodynamic environment. The effects of shear stress on the expression of human protease activated receptor-1 (PAR-1) and tissue plasminogen activator (tPA) mRNA and protein were investigated in human aortic smooth muscle cells (HASMCs). Under conditions of low shear stress (5 dyn/cm2), PAR-1 mRNA expression was increased transiently at 2 hours compared with stationary control values, whereas at high shear stress (25 dyn/cm2), mRNA expression was decreased (to 29% of stationary control; P〈0.05) at all examined time points (2 to 24 hours). mRNA half-life studies showed that this response was not due to increased mRNA instability. tPA mRNA expression was decreased (to 10% of stationary control; P〈0.05) by low shear stress after 12 hours of exposure and was increased (to 250% of stationary control; P〈0.05) after 24 hours at high shear stress. The same trends in PAR-1 mRNA levels were observed in rat smooth muscle cells, indicating that the effects of shear stress on human PAR-1 were not species-specific. Flow cytometry and ELISA techniques using rat smooth muscle cells and HASMCs, respectively, provided evidence that shear stress exerted similar effects on cell surface-associated PAR-1 and tPA protein released into the conditioned media. The decrease in PAR-1 mRNA and protein had functional consequences for HASMCs, such as inhibition of [Ca2+] mobilization in response to thrombin stimulation. These data indicate that human PAR-1 and tPA gene expression are regulated differentially by shear stress, in a pattern consistent with their putative roles in several arterial vascular pathologies.
    Keywords: Life Sciences (General)
    Type: Circulation research (ISSN 0009-7330); 83; 10; 1027-34
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