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101.
Irving W. Wainer John C. Chen Heli Parenteau Sami Abdullah Julie Ducharme Hiltrude Fieger Joanna Iredale 《Chirality》1994,6(4):347-354
The disposition of the enantiomers of hydroxychloroquine (HCQ) and its major metabolites in ocular tissues of rabbits has been studied. Both albino, New Zealand White (NZW), and pigmented animals were administered daily oral doses of rac-HCQ, (S)-HCQ or (R)-HCQ (20 mg/kg) over 1, 6, or 8 day periods or for 8 days followed by a 7-day washout period. At the end of the study periods, plasma and whole blood samples were collected and the rabbits were sacrificed. The eyes were collected, the aqueous humor removed with a syringe, and the eyes separated into the cornea, lens, vitreous body, iris, choroid-retina, sclera, and conjunctiva. The concentrations of (R)-HCQ, (S)-HCQ, and their respective metabolites were determined using a validated enantioselective liquid chromatographic assay. The data from these studies indicate that HCQ accumulated in both pigmented and nonpigmented ocular tissues. In the pigmented tissues, HCQ and its metabolites were bound to melanin and the binding was not enantiospecific. In the nonpigmented tissues and in the iris and retina-choroid of the NZW rabbits, the accumulation appeared to be the result of a reversible and enantioselective binding of HCQ and its metabolites to an unidentified biopolymer present in these ocular tissues. © 1994 Wiley-liss, Inc. 相似文献
102.
The uptake of bacteria and picoplankton sized fluorescentlylabelled beads was measured off the west coast of the SouthIsland of New Zealand in winter. Phytoflagellates and heterotrophicflagellates showed similar grazing rates on 0.49 µm beads,with mean clearance rates of 1.1 and 1.8 nl ind.1 h1,respectively. Clearance rates for 1.09 µm beads were 0.9nl ind.1 h1 for heterotrophic flagellates and0.5 nl ind.1 h1 for phytoflagellates. Non-loricateciliates had clearance rates of 1.5 µl ind.1 h1for the picoplankton sized particles. The heterotrophic flagellatesshowed no significant difference between clearance rates of0.49 and 1.09 µm particles. Phytoflagellates, however,showed an apparent preference for the smaller particles. Themeasurement of significant grazing by phytoflagellate populationsin the marine environment is important and indicates that weneed to reassess our concepts of food web structure. 相似文献
103.
Retha R. Newbold Rita B. Hanson Wendy N. Jefferson 《In vitro cellular & developmental biology. Animal》1994,30(8):519-528
Summary Although estrogens have been shown to stimulate a variety of morphologic and biochemical changes in the uterus in vivo, no
clear consistent demonstration of similar responses in vitro have been made; thus, a defined organ culture system using the
immature mouse uterus was established to study the possibility of demonstrating estrogenic responses in vitro. Uterine tissue
from immature outbred mice (17 to 24 days of age) were cut crosswise in 1-mm3 coins and cultured in a defined medium in the absence of serum, phenol red, or growth factor supplements. Diethylstilbestrol
(DES), a synthetic estrogen, was added to the media at doses ranging from 1 to 100 ng/ml. The effect of DES on uterine cell
proliferation was assessed by morphologic changes in uterine epithelial and stromal cells, increase in number of epithelial
cells per unit basement membrane, increase in height of luminal epithelial cells, and [3H]thymidine incorporation. Functional changes were determined by measuring the amounts of the estrogen-inducible uterine protein,
lactoferrin, that was localized in the epithelial cells and secreted into the media, and the localization of the estrogen
receptor in the cultured tissues. Results indicate that under the described conditions of culture, estrogens like DES can
induce morphologic and biochemical responses in the uterus that are similar to those seen in vivo. This organ culture system
will aid in the investigation of various mechanisms involved in the hormonal regulation of growth and differentiation of estrogen
target tissues. 相似文献
104.
Pierre Voisin Odile Viratelle Jeanne-Marie Girault Marcelle Morrison-Bogorad Julie Labouesse 《Journal of neurochemistry》1993,60(1):114-127
Abstract: The plasticity of astroglial glutamate and γ-aminobutyric acid (GABA) uptakes was investigated using mouse cerebellar cell cultures. The influence of external factors, such as different sera and/or the presence of neurons, was examined. Control autoradiography experiments showed that after short-term exposure to radioactive amino acids, granule cells took up neither glutamate nor GABA, and β-alanine predominantly inhibited astroglial GABA uptake. Astroglial uptake was quantified by measuring the radioactivity taken up by the cells in the culture and relating this measurement to the number of glial fibrillary acidic protein-positive cells present. Glutamate uptake was investigated in astroglial cultures and subcultures and in neuro-nal-astroglial cultures derived from postnatal day 4 mouse cerebella. In the absence of neurons, glutamate uptake increased during the first 9 days after plating and then leveled off. At 14 days in vitro in horse serum, which favors the differentiation of fibrous-like astrocytes, glutamate uptake related to astrocyte number was twice as high as in fetal calf serum. In the presence of cerebellar neurons, this rate was even higher. The specificity of the responsiveness of astrocytes to neurons with respect to glutamate uptake was investigated by comparing GABA uptake in the different culture conditions. Neurons also increased the rate of GABA uptake by astrocytes. Another component of the astroglial plasma membrane, the density of β-adrenergic receptors, was, however, not markedly affected by the presence of neurons. Hence, these results showed that in astrocytes plated from postnatal day 4 mouse cerebella, the level of neuro-transmitter uptake can be regulated in vitro by factors present in sera and by cerebellar neurons in the culture. However, this plasticity declined during development because astrocytes plated from postnatal day 8 cerebella and cultured under identical conditions were less active in glutamate uptake and were insensitive to the presence of horse serum. The latter observation suggested that the metabolic plasticity of astrocytes is restricted to a period defined early in cerebellar development and is no longer evident by postnatal day 8. 相似文献
105.
Evidence that the putative compatible solute 5-dimethylsulfoniopentanoate is an extraction artifact.
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A novel gas chromatography-mass spectrometry method for analyzing sulfonium compounds as their S-demethylated silyl derivatives has clarified the origin of 5-dimethylsulfoniopentanoate. This compound, previously reported from flowers of Diplotaxis tenuifolia (L.) DC. (Cruciferae), is generated from glucoerucin during treatment with hot 6 N HCl. Glucoerucin is the characteristic glucosinolate of D. tenuifolia. 相似文献
106.
Jeffrey D. Wood Lianhong Gu Paul J. Hanson Christian Frankenberg Lawren Sack 《Global Change Biology》2023,29(7):2015-2029
Soil and atmospheric droughts increasingly threaten plant survival and productivity around the world. Yet, conceptual gaps constrain our ability to predict ecosystem-scale drought impacts under climate change. Here, we introduce the ecosystem wilting point (ΨEWP), a property that integrates the drought response of an ecosystem's plant community across the soil–plant–atmosphere continuum. Specifically, ΨEWP defines a threshold below which the capacity of the root system to extract soil water and the ability of the leaves to maintain stomatal function are strongly diminished. We combined ecosystem flux and leaf water potential measurements to derive the ΨEWP of a Quercus-Carya forest from an “ecosystem pressure–volume (PV) curve,” which is analogous to the tissue-level technique. When community predawn leaf water potential (Ψpd) was above ΨEWP (=−2.0 MPa), the forest was highly responsive to environmental dynamics. When Ψpd fell below ΨEWP, the forest became insensitive to environmental variation and was a net source of carbon dioxide for nearly 2 months. Thus, ΨEWP is a threshold defining marked shifts in ecosystem functional state. Though there was rainfall-induced recovery of ecosystem gas exchange following soaking rains, a legacy of structural and physiological damage inhibited canopy photosynthetic capacity. Although over 16 growing seasons, only 10% of Ψpd observations fell below ΨEWP, the forest is commonly only 2–4 weeks of intense drought away from reaching ΨEWP, and thus highly reliant on frequent rainfall to replenish the soil water supply. We propose, based on a bottom-up analysis of root density profiles and soil moisture characteristic curves, that soil water acquisition capacity is the major determinant of ΨEWP, and species in an ecosystem require compatible leaf-level traits such as turgor loss point so that leaf wilting is coordinated with the inability to extract further water from the soil. 相似文献
107.
Juliette Gaëtan Sébastien Halary Maxime Millet Cécile Bernard Charlotte Duval Sahima Hamlaoui Amandine Hecquet Muriel Gugger Benjamin Marie Neha Mehta David Moreira Fériel Skouri-Panet Cynthia Travert Elodie Duprat Julie Leloup Karim Benzerara 《Environmental microbiology》2023,25(3):751-765
The formation of intracellular amorphous calcium carbonates (iACC) has been recently observed in a few cultured strains of Microcystis, a potentially toxic bloom-forming cyanobacterium found worldwide in freshwater ecosystems. If iACC-forming Microcystis are abundant within blooms, they may represent a significant amount of particulate Ca. Here, we investigate the significance of iACC biomineralization by Microcystis. First, the presence of iACC-forming Microcystis cells has been detected in several eutrophic lakes, indicating that this phenomenon occurs under environmental conditions. Second, some genotypic (presence/absence of ccyA, a marker gene of iACC biomineralization) and phenotypic (presence/absence of iACC) diversity have been detected within a collection of strains isolated from one single lake. This illustrates that this trait is frequent but also variable within Microcystis even at a single locality. Finally, one-third of publicly available genomes of Microcystis were shown to contain the ccyA gene, revealing a wide geographic and phylogenetic distribution within the genus. Overall, the present work shows that the formation of iACC by Microcystis is common under environmental conditions. While its biological function remains undetermined, this process should be further considered regarding the biology of Microcystis and implications on the Ca geochemical cycle in freshwater environments. 相似文献
108.
Maria A. Soto Dhwani Desai Catherine Bannon Julie LaRoche Erin M. Bertrand 《Environmental microbiology》2023,25(7):1300-1313
Cobalamin availability can influence primary productivity and ecological interactions in marine microbial communities. The characterization of cobalamin sources and sinks is a first step in investigating cobalamin dynamics and its impact on productivity. Here, we identify potential cobalamin sources and sinks on the Scotian Shelf and Slope in the Northwest Atlantic Ocean. Functional and taxonomic annotation of bulk metagenomic reads, combined with analysis of genome bins, were used to identify potential cobalamin sources and sinks. Cobalamin synthesis potential was mainly attributed to Rhodobacteraceae, Thaumarchaeota, and cyanobacteria (Synechococcus and Prochlorococcus). Cobalamin remodelling potential was mainly attributed to Alteromonadales, Pseudomonadales, Rhizobiales, Oceanospirilalles, Rhodobacteraceae, and Verrucomicrobia, while potential cobalamin consumers include Flavobacteriaceae, Actinobacteria, Porticoccaceae, Methylophiliaceae, and Thermoplasmatota. These complementary approaches identified taxa with the potential to be involved in cobalamin cycling on the Scotian Shelf and revealed genomic information required for further characterization. The Cob operon of Rhodobacterales bacterium HTCC2255, a strain with known importance in cobalamin cycling, was similar to a major cobalamin producer bin, suggesting that a related strain may represent a critical cobalamin source in this region. These results enable future inquiries that will enhance our understanding of how cobalamin shapes microbial interdependencies and productivity in this region. 相似文献
109.
Julie E. Jones 《Journal of industrial microbiology & biotechnology》1993,12(3-5):268-272
Summary This paper describes the development and operation of a database/models base/expert system funded by the Ministry of Agriculture, Fisheries and Food in the UK. As part of an on-going coordinated program on predictive microbiology, the system being established involves storage of data and models relevant to changes in populations of food-borne pathogens under given conditions. The system is due to be completed by March 1994. 相似文献
110.
Laetitia Mathon Virginie Marques Stéphanie Manel Camille Albouy Marco Andrello Emilie Boulanger Julie Deter Régis Hocdé Fabien Leprieur Tom B. Letessier Nicolas Loiseau Eva Maire Alice Valentini Laurent Vigliola Florian Baletaud Sandra Bessudo Tony Dejean Nadia Faure Pierre-Edouard Guerin Meret Jucker Jean-Baptiste Juhel Kadarusman Andrea Polanco F. Laurent Pouyaud Dario Schwörer Kirsten F. Thompson Marc Troussellier Hagi Yulia Sugeha Laure Velez Xiaowei Zhang Wenjun Zhong Loïc Pellissier David Mouillot 《Global Ecology and Biogeography》2023,32(8):1336-1352