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101.
Pituch-Noworolska A Majka M Janowska-Wieczorek A Baj-Krzyworzeka M Urbanowicz B Malec E Ratajczak MZ 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2003,41(1):13-21
The trans-differentiation hypothesis of adult tissue-specific stem cells has been recently questioned because of insufficient proof that the so-called plasticity experiments were performed on pure populations of tissue-specific stem cells. It was shown recently, for example, that the formation of haematopoietic colonies by muscle cells depended on the presence of haematopoietic stem/progenitor cells residing within the muscle tissue and hence was not related to the plasticity of the muscle stem cells. The explanation for the presence in, or homing into, muscles of haematopoietic stem cells is, however, not clear. In our study, we hypothesised that muscle tissues secrete stromal-derived factor (SDF)- 1, an alpha-chemokine for haematopoietic stem cells (HSC), which could attract HSC circulating in peripheral blood into muscle tissue. We found, using RT-PCR and immunocytochemistry, that SDF-1 was expressed in human heart and skeletal muscles. Moreover, muscle satellite cells, which are pivotal for regeneration of muscle, highly expressed on their surface CXCR4, a G-protein-coupled receptor that binds SDF-1. To determine whether the CXCR4 receptor is functional on muscle satellite/progenitor cells, we stimulated murine satellite cells (the C2C12 cell line) with SDF-1 and demonstrated the phosphorylation of p42/44 MAPK and AKT serine-threonine kinase in these cells. Moreover, we showed that SDF-1 gradient chemoattracts these cells. We postulate that the CXCR4-positive muscle satellite and CXCR4-positive HSC circulating in the peripheral blood compete for occupancy of SDF-1-positive stem cell niches that are present in bone marrow and muscle tissues. Thus, we suggest that competition for common niches by various circulating CXCR4-positive stem cells and their ability to home to the SDF-1-positive niches in various organs, is a better explanation than stem cell plasticity of why (i) haematopoietic colonies can be cultured from muscles and (ii) early muscle progenitors could be cultured from bone marrow. 相似文献
102.
Agnieszka Szuba Łukasz Marczak Izabela Ratajczak Anna Kasprowicz-Maluśki Joanna Mucha 《Environmental microbiology》2020,22(9):3754-3771
Ectomycorrhizae (ECMs) are a highly context-dependent interactions that are not always beneficial for the plant host, sometimes leading to a decrease in plant growth. However, the molecular status of these plants remains unknown. We studied Populus × canescens microcuttings characterized by impaired growth in response to colonization by a Paxillus involutus strain via integrative proteomics–metabolomics analyses. The analysed strain was characterized by low compatibility and formed only mantles, not a Hartig net, in the majority of root tips. The increased abundance of photosynthetic proteins and foliar carbohydrates co-occurred with signals of intensified resource exchange via the stems of colonized plants. In the roots, intensified C metabolism resulted in the biosynthesis of secondary C compounds unavailable to the fungal partner but also C skeletons necessary to increase insufficient N uptake from the hyphae. The stress response was also detected in colonized plants but was similar to that reported previously during mutualistic ECM interactions. In colonized poplar plants, mechanisms to prevent imbalanced C/N trade-offs were activated. Root metabolism strongly depended on features of the whole plant, especially the foliar C/N budget. However, despite ECM-triggered growth impairment and the foliar nutrient status, the fungal partner was recognized to be a symbiotic partner. 相似文献
103.
The seeds of pedunculate oak (Quercus robur L.) were subjected to slow (S) and rapid (R) desiccation at desiccation rates of 0.16 and 0.39% H2O per hour, respectively. Till ca. 40% water content (WC) the germination capacity of seeds in the S and R variants was high
(ca. 100%). Between 40 and 28% WC, germination capacity declined to 20 and 50% in S and R variants, respectively. The decrease
in seed viability was accompanied by a significant increase of electrolyte leakage from embryonic axes (28% for S and 15%
for R variants). In the embryonic axes of seeds subjected to slow desiccation, malondialdehyde (MDA) and free fatty acid (FFA)
contents were significantly higher than those in R variants, indicating greater membrane damage due to lipid peroxidation.
The production of ROS (H2O2 and O2·−) was significantly higher in S than in R variants. The low molecular weight antioxidants α-tocopherol, ascorbic acid (ASA),
and phenolic compounds indicated different reactions in response to desiccation stress. ASA levels decreased during desiccation
to a similar degree in both the S and R variants. A significant decrease of total phenols was observed in R variant, which
coincided with a significant increase of guaiacol peroxidase (POX) activity. α-Tocopherol content was significantly higher
in the embryonic axes of seeds subjected to rapid drying. The activities of the enzymatic scavengers APX and GR had similar
runs and were slightly higher in R variant. The activities of POX and SOD were significantly higher in the embryonic axes
of seeds subjected to rapid drying. These results show that rapid dehydration of Q. robur seeds leads to the greater mobilization of antioxidant system in embryonic axes, particularly increased levels of α-tocopherol
and POX and SOD activities, in the first stages of water loss. This mobilization has a greater impact on maintenance of higher
viability of seeds after drying to lower level of WC. 相似文献
104.
M Z Ratajczak C Szczylik W W Jedrzejczak 《Polski tygodnik lekarski (Warsaw, Poland : 1960)》1991,46(40-42):764-769
Serum creatinine and urea changes as well as protein, erythrocytes, and leucocytes excretion with the urine in allogenic bone marrow recipients are discussed. An increase in serum creatinine and urea together with proteinuria and hematuria were noted in 1/3 of patients treated with busulphan and cyclophosphamide prior to bone marrow transplantation. In cases of bone marrow graft rejection or post-transplantation complications no abnormalities in the value of investigated parameters were noted, especially immediately before death. Possible causes of such renal function disorders are also discussed. 相似文献
105.
Sham S. Kakar Mariusz Z. Ratajczak Karen S. Powell Mana Moghadamfalahi Donald M. Miller Surinder K. Batra Sanjay K. Singh 《PloS one》2014,9(9)
Currently, the treatment for ovarian cancer entails cytoreductive surgery followed by chemotherapy, mainly, carboplatin combined with paclitaxel. Although this regimen is initially effective in a high percentage of cases, unfortunately within few months of initial treatment, tumor relapse occurs because of platinum-resistance. This is attributed to chemo-resistance of cancer stem cells (CSCs). Herein we show for the first time that withaferin A (WFA), a bioactive compound isolated from the plant Withania somnifera, when used alone or in combination with cisplatin (CIS) targets putative CSCs. Treatment of nude mice bearing orthotopic ovarian tumors generated by injecting human ovarian epithelial cancer cell line (A2780) with WFA and cisplatin (WFA) alone or in combination resulted in a 70 to 80% reduction in tumor growth and complete inhibition of metastasis to other organs compared to untreated controls. Histochemical and Western blot analysis of the tumors revealed that inclusion of WFA (2 mg/kg) resulted in a highly significant elimination of cells expressing CSC markers - CD44, CD24, CD34, CD117 and Oct4 and downregulation of Notch1, Hes1 and Hey1 genes. In contrast treatment of mice with CIS alone (6 mg/kg) had opposite effect on those cells. Increase in cells expressing CSC markers and Notch1 signaling pathway in tumors exposed to CIS may explain recurrence of cancer in patients treated with carboplatin and paclitaxel. Since, WFA alone or in combination with CIS eliminates putative CSCs, we conclude that WFA in combination with CIS may present more efficacious therapy for ovarian cancer. 相似文献
106.
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108.
Magali Joffraud Joanna Ratajczak Miriam Valera‐Alberni Roy Combe Antonio Zorzano Carles Cantó 《The EMBO journal》2017,36(11):1543-1558
Mitochondrial fusion and fission events, collectively known as mitochondrial dynamics, act as quality control mechanisms to ensure mitochondrial function and fine‐tune cellular bioenergetics. Defective mitofusin 2 (Mfn2) expression and enhanced mitochondrial fission in skeletal muscle are hallmarks of insulin‐resistant states. Interestingly, Mfn2 is highly expressed in brown adipose tissue (BAT), yet its role remains unexplored. Using adipose‐specific Mfn2 knockout (Mfn2‐adKO) mice, we demonstrate that Mfn2, but not Mfn1, deficiency in BAT leads to a profound BAT dysfunction, associated with impaired respiratory capacity and a blunted response to adrenergic stimuli. Importantly, Mfn2 directly interacts with perilipin 1, facilitating the interaction between the mitochondria and the lipid droplet in response to adrenergic stimulation. Surprisingly, Mfn2‐adKO mice were protected from high‐fat diet‐induced insulin resistance and hepatic steatosis. Altogether, these results demonstrate that Mfn2 is a mediator of mitochondria to lipid droplet interactions, influencing lipolytic processes and whole‐body energy homeostasis. 相似文献
109.
Patch based predation in a southern Appalachian stream 总被引:1,自引:0,他引:1
Streams are characterized by high degrees of patchiness that could influence the role of predators in these systems. Here we assess the impact of predatory benthic fishes on benthic macroinvertebrate density, biomass, and community structure at the patch scale in a fourth order stream in the southern Appalachians. We tested the role of predation in two different patch types: patches inhabited by adult mottled sculpin ( Cottus bairdi ) and random patches. We placed 30 basket pairs (one open to fish predation, and one from which fish predators were excluded) in the streambed at each patch type. We also tested for potential basket effects by setting up a basket control area. Although there was some evidence of basket artifacts on macroinvertebrate density in sculpin patches, these artifacts were not consistent and we do not feel that they affected our results because predators did not affect macroinvertebrate density. In random patches, predation did not significantly affect macroinvertebrate density or biomass. Predators significantly reduced macroinvertebrate biomass in sculpin patches but did not affect prey density. When the data-set was size-limited to exclude macroinvertebrates too large for consumption by sculpin, macroinvertebrate biomass did not differ significantly between exclusion and open baskets. This suggests that sculpin can reduce macroinvertebrate biomass through a combination of consumption and by predator-induced emigration of large macroinvertebrates into areas that are protected from sculpin. In addition, invertebrate predator biomass was higher in predator exclusion baskets in sculpin patches indicating that predation pressure remained high in the exclusion baskets despite fish exclusion. These results illustrate the heterogeneity of streams and the effect of small-scale differences (e.g. location of predators' territories) on local processes. Experiments that utilize these differences can provide insights into these stream processes. 相似文献
110.