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11.
Marta E. Capala Henny Maat Francesco Bonardi Vincent van den Boom Jeroen Kuipers Edo Vellenga Ben N. G. Giepmans Jan Jacob Schuringa 《PloS one》2015,10(5)
Leukemic stem cells (LSCs) reside within bone marrow niches that maintain their relatively quiescent state and convey resistance to conventional treatment. Many of the microenvironmental signals converge on RAC GTPases. Although it has become clear that RAC proteins fulfill important roles in the hematopoietic compartment, little has been revealed about the downstream effectors and molecular mechanisms. We observed that in BCR-ABL-transduced human hematopoietic stem/progenitor cells (HSPCs) depletion of RAC2 but not RAC1 induced a marked and immediate decrease in proliferation, progenitor frequency, cobblestone formation and replating capacity, indicative for reduced self-renewal. Cell cycle analyses showed reduced cell cycle activity in RAC2-depleted BCR-ABL leukemic cobblestones coinciding with an increased apoptosis. Moreover, a decrease in mitochondrial membrane potential was observed upon RAC2 downregulation, paralleled by severe mitochondrial ultrastructural malformations as determined by automated electron microscopy. Proteome analysis revealed that RAC2 specifically interacted with a set of mitochondrial proteins including mitochondrial transport proteins SAM50 and Metaxin 1, and interactions were confirmed in independent co-immunoprecipitation studies. Downregulation of SAM50 also impaired the proliferation and replating capacity of BCR-ABL-expressing cells, again associated with a decreased mitochondrial membrane potential. Taken together, these data suggest an important role for RAC2 in maintaining mitochondrial integrity. 相似文献
12.
Rolien H Free G Jolanda Elving Henny C van der Mei Ranny van Weissenbruch Frans W J Albers Henk J Busscher 《Biofouling》2013,29(1):69-76
Laryngectomized patients use indwelling silicone rubber voice prostheses, placed in a surgically created fistula in between the trachea and the esophagus, for voice and speech rehabilitation. At the esophageal side, these voice prostheses rapidly become colonized by a thick biofilm consisting of a variety of oral and skin bacteria and yeasts, and on average, after 3–4 months a prosthesis has to be replaced. In this study, the influence of caffeinated soft drinks on biofilm formation on silicone rubber voice prostheses has been investigated in a modified Robbins device. Robbins devices were first inoculated with the total cultivable microflora from an explanted voice prosthesis for 3 d, after which the devices were perfused three times daily over a 12 day period with 650 ml of either phosphate buffered saline or carbonated mineral water (controls), caffeinated soft drinks (two types), or a decaffeinated and a sugar‐free version of one of the caffeinated soft drinks. At the end of a day, during the experimental period, the devices were filled with growth medium for 30 min. Both caffeinated soft drinks reduced bacterial prevalence in the biofilms to 1–5% of the control, while yeasts thrived in voice prosthetic biofilms exposed to caffeinated soft drinks. Neither the controls, nor the decaffeinated soft drink, nor the sugar‐free version of this showed these effects on bacterial prevalence. 相似文献
13.
Dr. Henny C. van der Mei Marjorie M. Cowan Henk J. Busscher 《Current microbiology》1991,23(6):337-341
Acinetobacter calcoaceticus RAG-1 and MR-481, two standard strains used in microbial adhesion to hydrocarbons (MATH), were characterized by contact angles, pH-dependent zeta potentials, elemental surface composition by X-ray photoelectron spectroscopy (XPS), and molecular composition by infrared spectroscopy (IR). Negatively stained (methylamine tungstate) and ruthenium red-stained cells were studied by transmission electron microscopy to reveal the absence or presence of surface appendages. Despite the fact thatA. calcoaceticus RAG-1 is known to be extremely hydrophobic in MATH, whereas MR-481 is a completely non-hydrophobic mutant, neither XPS nor IR indicated a significant difference in chemical composition of the cell surfaces. Contact angles with polar liquids, water and formamide, were considerably higher on RAG-1 than on MR-481, in accordance with their relative hydrophobicities as measured by MATH. However, no significant differences in contact angles were observed between the two strains with apolar liquids like diiodomethane,-bromonaphthalene, and hexadecane. Fibrous extensions on RAG-1, observed after ruthenium red staining, were absent on the non-hydrophobic mutant MR-481. Tentatively, these extensions could be held responsible for the hydrophobicity ofA. calcoaceticus RAG-1. 相似文献
14.
S. A. Crowe J. A. Maresca C. Jones A. Sturm C. Henny D. A. Fowle R. P. Cox E. F. Delong D. E. Canfield 《Geobiology》2014,12(4):322-339
Ferruginous Lake Matano, Indonesia hosts one of the deepest anoxygenic photosynthetic communities on Earth. This community is dominated by low‐light adapted, BChl e‐synthesizing green sulfur bacteria (GSB), which comprise ~25% of the microbial community immediately below the oxic‐anoxic boundary (OAB; 115‐120 m in 2010). The size of this community is dependent on the mixing regime within the lake and the depth of the OAB—at ~117 m, the GSB live near their low‐light limit. Slow growth and C‐fixation rates suggest that the Lake Matano GSB can be supported by sulfide even though it only accumulates to scarcely detectable (low μm to nm ) concentrations. A model laboratory strain (Chlorobaculum tepidum) is indeed able to access HS? for oxidation at nm concentrations. Furthermore, the GSB in Lake Matano possess a full complement of S‐oxidizing genes. Together, this physiological and genetic information suggests that deep‐water GSB can be supported by a S‐cycle, even under ferruginous conditions. The constraints we place on the metabolic capacity and physiology of GSB have important geobiological implications. Biomarkers diagnostic of GSB would be a good proxy for anoxic conditions but could not discriminate between euxinic and ferruginous states, and though GSB biomarkers could indicate a substantial GSB community, such a community may exist with very little metabolic activity. The light requirements of GSB indicate that at light levels comparable to those in the OAB of Lake Matano or the Black Sea, GSB would have contributed little to global ocean primary production, nutrient cycling, and banded iron formation (BIF) deposition in the Precambrian. Before the proliferation of oxygenic photosynthesis, shallower OABs and lower light absorption in the ocean's surface waters would have permitted greater light availability to GSB, potentially leading to a greater role for GSB in global biogeochemical cycles. 相似文献
15.
16.
Jin Cui Jianjun Chen Richard J. Henny 《In vitro cellular & developmental biology. Plant》2009,45(1):34-43
Plant regeneration through direct somatic embryogenesis in Aeschynanthus radicans ‘Mona Lisa’ was achieved in this study. Globular somatic embryos were formed directly from cut edges of leaf explants and
cut ends or on the surface of stem explants 4 wk after culture on Murashige and Skoog (MS) medium supplemented with N-phenyl-N′-1, 2, 3-thiadiazol-5-ylurea (TDZ) with α-naphthalene acetic acid (NAA), TDZ with 2,4-dichlorophenoxyacetic acid (2,4-D),
or 6-benzylaminopurine (BA) or kintin (KN) with 2,4-D. MS medium containing 9.08 μM TDZ and 2.68 μM 2,4-D resulted in 71%
of stem explants producing somatic embryos. In contrast, 40% of leaf explants produced somatic embryos when induced in medium
containing 6.81 μM TDZ and 2.68 μM 2,4-D. Somatic embryos matured, and some germinated into small plants on the initial induction
medium. Up to 64% of stem explants cultured on medium supplemented with 9.08 μM TDZ + 2.68 μM 2,4-D, 36% of leaf explants
cultured on medium containing 6.81 μM TDZ and 2.68 μM 2,4-D had somatic embryo germination before or after transferring onto
MS medium containing 8.88 μM BA and 1.07 μM NAA. Shoots elongated better and roots developed well on MS medium without growth
regulators. Approximately 30–50 plantlets were regenerated from each stem or leaf explant. The regenerated plants grew vigorously
after transplanting to a soil-less substrate in a shaded greenhouse with more than a 98% survival rate. Three months after
their establishment in the shaded greenhouse, 500 plants regenerated from stem explants were morphologically evaluated, from
which five types of variants that had large, orbicular, elliptic, small, and lanceolate leaves were identified. Flow cytometry
analysis of the variants along with the parent showed that they all had one identical peak, indicating that the variant lines,
like the parent, were diploid. The mean nuclear DNA contents of the variant lines and their parent ranged from 4.90 to 4.99 pg
2C−1, which were not significantly different statistically. The results suggest that the regenerated plants have a stable ploidy
level, and the regeneration method established in this study can be used for rapid propagation of ploidy-stable Aeschynanthus radicans. 相似文献
17.
Two Asian influenza strains, the Hong Kong strain and an Equi-2 influenza strain have been investigated. Adsorption isotherms of purified neuraminidases from these strains with isolated antibodies from homologous antisera are given. Cross testing by neuraminidase inhibition and haemagglutination inhibition are reported. Hong Kong neuraminidase appears to be indistinguishable from the earlier Asian neuraminidases, and not related to Equi-2 influenza neuraminidase. The haemagglutinin from the Hong Kong strain is related to earlier Asian strains as well as to the equine strain.In collaboration with the Chief Medical Officer of Health and Epidemiology, Department of Public Health, Den Haag, The Netherlands.It is a pleasure to express our thanks to Mr. J. Jacobs, N. V. Philips Duphar, Weesp (The Netherlands) for his interesting discussions and suggestions; and to Mr. H. de Jonge, Department of Medical Statistics, University of Leiden (The Netherlands) for his advice. 相似文献
18.
19.
Duncan Thomas Teresa Seeman Alan Potter Peifeng Hu Eileen Crimmins Elizabeth Henny Herningtyas 《Biodemography and social biology》2018,64(1):43-62
Glycated hemoglobin (HbA1c) measured using high-performance liquid chromatography (HPLC) assays with venous blood and dried blood spots (DBS) are compared for 143 paired samples collected in Aceh, Indonesia. Relative to gold-standard venous-blood values, DBS-based values reported by the HPLC are systematically upward biased for HbA1c<8% and the fraction diabetic (HbA1c ≥ 6.5%) is overstated almost five-fold. Inspection of chromatograms from DBS assays indicates the % glycosylated calculated by the HPLC excludes part of the hemoglobin A which is misidentified as a hemoglobin variant. Taking this into account, unbiased DBS-based values are computed using data from the machine-generated chromatograms. When the DBS are collected in a clinic-like setting, under controlled humidity/temperature conditions, the recalculated values are almost identical to venous-based values. When DBS are collected under field conditions, the recalculated values are unbiased, but only about half the HbA1c values are measured reliably, calling into question the validity of the other half. The results suggest that collection conditions, particularly humidity, affect the quality of the DBS-based measures. Cross-validating DBS-based HbA1c values with venous samples collected under exactly the same environmental conditions is a prudent investment in population-based studies. 相似文献
20.
Mallet N Micklem BR Henny P Brown MT Williams C Bolam JP Nakamura KC Magill PJ 《Neuron》2012,74(6):1075-1086
Different striatal projection neurons are the origin of?a?dual organization essential for basal ganglia function. We have defined an analogous division of labor in the external globus pallidus (GPe) of Parkinsonian rats, showing that the distinct temporal activities of two populations of GPe neuron in?vivo are?underpinned by distinct molecular profiles and axonal connectivities. A first population of prototypic GABAergic GPe neurons fire antiphase to subthalamic nucleus (STN) neurons, often express parvalbumin, and target downstream basal ganglia nuclei, including STN. In contrast, a second population (arkypallidal neurons) fire in-phase with STN neurons, express preproenkephalin, and only innervate the striatum. This novel cell type provides the largest extrinsic GABAergic innervation of striatum, targeting both projection neurons and interneurons. We conclude that GPe exhibits several core components of?a dichotomous organization as fundamental as?that in striatum. Thus, two populations of GPe neuron?together orchestrate activities across all basal ganglia nuclei in a cell-type-specific manner. 相似文献