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  • Electron microscopy  (1,196)
  • Rat  (826)
  • 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
  • Bacteria
  • Springer  (2,136)
  • Lagos (Nigeria)  (6)
  • Istituto Nazionale di Geofisica e Vulcanologia  (5)
  • American Chemical Society
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  • 1
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    Springer Nature | Springer
    Publication Date: 2024-04-05
    Description: This open access book offers a comprehensive overview of the role and potential of microorganisms in the degradation and preservation of cultural materials (e.g. stone, metals, graphic documents, textiles, paintings, glass, etc.). Microorganisms are a major cause of deterioration in cultural artefacts, both in the case of outdoor monuments and archaeological finds. This book covers the microorganisms involved in biodeterioration and control methods used to reduce their impact on cultural artefacts. Additionally, the reader will learn more about how microorganisms can be used for the preservation and protection of cultural artefacts through bio-based and eco-friendly materials. New avenues for developing methods and materials for the conservation of cultural artefacts are discussed, together with concrete advances in terms of sustainability, effectiveness and toxicity, making the book essential reading for anyone interested in microbiology and the preservation of cultural heritage.
    Keywords: Microbiology ; Cultural Heritage ; Microbial Ecology ; Microbial Genetics and Genomics ; Enzymology ; Applied Microbiology ; Microbial Genetics ; Industrial Microbiology ; Open Access ; Restoration ; Conservation ; Biodeterioration ; Bioweathering ; Bioremediation ; Biocleaning ; Biotechnology ; Green Chemistry ; Fungi ; Bacteria ; Artwork ; Antimicrobial protection ; Biocides ; Microbiology (non-medical) ; Cultural studies ; Social & cultural history ; Ecological science, the Biosphere ; Genetics (non-medical) ; Biochemistry ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSG Microbiology (non-medical) ; thema EDItEUR::J Society and Social Sciences::JB Society and culture: general::JBC Cultural and media studies::JBCC Cultural studies ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAF Ecological science, the Biosphere ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSB Biochemistry
    Language: English
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  • 2
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24208 | 19325 | 2018-05-19 06:39:34 | 24208 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: The microbial load of four different fish species from five different market locations in Ibadan metropolis were determined using standard microbiological procedures. The bacteria count of fish sampled from Ojo market was the highest while the bacteria count of the fish sample from Bodija market was the lowest. There was no significant difference (p〈0.05) in the microbial load of the fish sampled from various market locations in Ibadan metropolis. Similarly, there was no significant difference (p〉0.05) in the microbial load on various fish species sold in Ibadan metropolis. The isolated bacteria from the study were: E. coli, Salmonella spp, Klebsiella spp, Staphylococcus aureus, Aerosomonas spp, Pseudomonas spp, Vibrio spp, Serratia spp, Chromobacterium spp, Enterobacteria spp and Shigella spp. The fungi count of fish sampled from Omi markets was the highest while the fungi count of the fish sampled from Ojo market was the lowest. The following fungi were however isolated from the study: Aspergillus flavus, Penicillium spp, Fusarium oxysporum, Trrichoderma spp and Ceotrichium albidium. The study shows that reheating may be necessary to destroy or inactivate micro-organisms in smoked fish before consumption.
    Description: Includes: 2 tables and 2 figures.;Also includes: 17 refernces.
    Keywords: Fisheries ; Nigeria ; Ibadan ; Bacteria ; Fungi ; Market ; Fish species ; freshwater environment ; Microbial contamination ; Microorganisms ; Bacteria ; Freshwater fish ; Cured products ; Sample contamination ; Fungi ; Public health ; Quality assurance ; Disinfection
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 223-227
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  • 3
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24166 | 19325 | 2018-05-13 18:40:22 | 24166 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Probiotics are a promising feed additive to stimulate animal growth and secure a low disease response in aquaculture industry where there are high stocking densities in shrimp and fish production. Fermented locust beans (Parkia biglobosa) are known to be rich in protein and used as food condiment. Probiotic bacteria were isolated from this locally available food material. Culture and characterizations of isolates were carried out. Sugar fermentation patterns were determined by using an API 50 CHL system and incubation were performed anaerobically at 37~'C. MRS broth culture grown at 37~'C overnight was added to 9ml of MRS Agar and the bacteria were incubated at 37~'C for 24 and 48 hrs. Discrete and single colony of lactobacillus was isolated using colony morphology and biochemical tests. The most significant viable taxa isolated was Lactobacillus fermentum at a pH range of (3.0-8.0), while the least viable taxa isolated was Leuconostoc mesenteroides ssp. Microscopically they were Grampositive, rod shaped, non- motile, catalase negative and absence of Endospore.
    Description: Includes: 2 tables and 2 plates.;Also includes: 15 references.
    Keywords: Aquaculture ; Nigeria ; Lagos ; Locust bean ; Probiotics ; Lactobacillus ; Probiotics ; freshwater environment ; Feed ; Additives ; Aquaculture ; Microorganisms ; Bacteria ; Disease resistance ; Fermented products ; Fish culture ; Shrimp culture
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 60-63
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  • 4
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24224 | 19325 | 2018-05-19 07:11:26 | 24224 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Jabi Lake is a natural water body in Abuja Federal Capital Territory (FCT). It was expanded for commercial fishing following relocation of Nigeria's headquarters to Abuja in 1993. Quantitative analysis of microbiological status of water and fish from the Lake was carried out. Samples were collected from the dam site, open water, middle lake and inlet. Result reveal that total coliform count which are indicators of pollution are high (2.0 x 103 cfu/ml, 1.1 x 103 cfu/ml, 1.0 x 103 cfu/ml and 1.1 x 103 cfu/ml for dam site, open water, middle lake, and inlet respectively). Total viable count too is high (9.2 x 103 cfu/ml, 4.9 x 103 cfu/ml, 4.6 x 103 cfu/ml and 4.9 x 103 cfu/ml for dam site, open water, middle lake and inlet respectively). There are no coliform bacteria in the muscle of the fish. High bacterial load is an indication of biological pollution and these calls for restraint on the side of those who are using the lake as site for refuse dump.
    Description: Includes: 10 references.
    Keywords: Fisheries ; Pollution ; Nigeria ; Jabi Lake ; Jabi lake ; Water ; Fish ; Bacteria ; freshwater environment ; Microbiology ; Fish ; Pollution ; Water pollution ; Lake fisheries ; Fishery surveys ; Bacteria ; Baseline studies ; Water sampling ; Microbial contamination ; Muscles ; Freshwater fish ; Pollution surveys ; Water analysis ; Freshwater pollution
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 284-286
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  • 5
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24185 | 19325 | 2018-05-16 14:41:02 | 24185 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Bacteria has been implicated in food poisoning, and smoked fish is not an exception.Generally, fish is highly susceptible to spoilage; therefore this study evaluated the bacteria load in smoked fish from three major locations in Shiroro area of Niger State namely; Gwada, Kuta and Zumba.The smoked fish samples collected from these locations were smeared at both the gills and head regions of the fishes. The bacteria samples identified were Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermis, Pseudomonas aeruginosa, and Samonella typhi, which were common to all the three locations sampled, while only Streptococcus feacaliswas only was found to be present in both Kuta and Zumba location.The frequency of occurrence of these 68 bacteria samples isolated ranges from 8 - 20%, with Bacillius subtilis having the highest occurrence and Pseudomonas aeruginosa have the least occurrence. Out of the total 68 samples, 14 skin samples (20.6%) and 5 gills samples (7.4%) exceeded the acceptable limits of total mesophilic aerobic counts which were 10〈sup〉6〈/sup〉 - 10〈sup〉7〈/sup〉 cfu/g. In the case of total coliform counts, 12 skin samples (17.6%) and 7 gills samples (10.3%) exceeded the acceptable limit which is 4.0 x 102, while in the case of Staphylococcus aureus, 4 skin samples (5.9%) and 2 gills samples (2.9%) exceeded the acceptable limit which is 103 cfu/g. Similarly 3 skin samples (4.4%) and 1 gill sample (1.5%) exceeded the acceptable limit of Salmonella typhi which is 104 cfu/g.
    Description: Includes: 4 tables.;Also includes: 21 references.
    Keywords: Fisheries ; Health ; Escherichia coli ; Bacillus subtilis ; Staphylococcus aureus ; Staphylococcus epidermis ; Pseeudomonas aeruginosa ; Nigeria ; Shiroro L. ; Bacteria ; Smoked (Clarias spp) fish ; Location and recommended values ; brackishwater environment ; freshwater environment ; marine environment ; Bacteria ; Food poisoning ; Cured products ; Fish ; Fish spoilage ; Acceptability ; Lake fisheries ; Gills ; Brain ; Evaluation
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 140-144
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  • 6
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24222 | 19325 | 2018-05-19 07:06:04 | 24222 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: A total of 2,800 tilapia (Oreochromis niloticus) were stocked in seven duplicates 5 by 4 m2 earthen ponds in NIFFR Integrated Farm, New-Bussa, Niger-State. Raw and sterilized poultry manure of 0.13 to 0.52 kg/m3 concentrations were used to fertilize the ponds with the unfertilized ponds serving as control. The following bacteria were isolated from the cow dung manure; Escherichia coli, E. co1iOl57:H7, Aeromonas hydrophila,Salmonella typhi, Shigella dysenteriae and Staphylococcus aureus. The fish samples from the 0.13 and 0.26 kg/m3 sterilized manure fertilized ponds had zero count in the muscles while samples from other ponds had pathogens in their fish muscles. The study revealed that fish samples from sterilized manures were better in terms of microbial safety for fish productions hence sterilized manure are recommended for use in fish production to ensure the microbial safety of the fish, handlers and that of the consumers.
    Description: includes: 13 references.
    Keywords: Aquaculture ; Oreochromis niloticus ; Escherichia coli ; Aeromonas hydrophila ; Samonela typhi ; Shigella dysenteriae ; Staphylococcus aureus ; Nigeria ; Niger State ; Catfish ; Pathogens ; Microbial quality ; Raw and sterilized manue ; freshwater environment ; Bacteria ; Freshwater fish ; Fish culture ; Fish ponds ; Manure ; Microorganisms ; Freshwater aquaculture ; Aquaculture products ; Food fish ; Quality assurance ; Muscles ; Microbial contamination
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 278-280
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  • 7
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    FISON | Lagos (Nigeria)
    In:  http://aquaticcommons.org/id/eprint/24596 | 19325 | 2018-05-20 16:13:09 | 24596 | Fisheries Society of Nigeria
    Publication Date: 2021-07-15
    Description: Sixty apparently healthy Heterobranchus bidorsalis and Clarias anguillaris from NIFFR were cultured and 30 each from Monai and wara villages as wild environments were obtained for the studies. The total bacterial load varied from 2.2 x l05 to 1.08 x l08 and 2.27 x 105 to 6.3 x l08 CFU/g of the skin of C. anguillaris and H.bidorsalis in the culture respectively, while the load varied from 1.77 x 105 to 1.17 x l08 and 2.27 x 105 to 9.0 x l07 CFU/g in the wild respectively. Eleven bacterial general species were identified which include: Bacillus species B.firmus, Pseudomonas species, P. aeruginosa, Escherichia coli, Klebsiella aerogenes, K. ozaenae, Staphylococcus aureus, Streptococcus species, S.faecalis, and Aeromonas species. The aims of this investigation is to compare the type and the load of bacteria isolates on the skin of catfish in both culture and wild environment.
    Description: Includes: 7 references.
    Keywords: Aquaculture ; Fisheries ; Clarias anguillaris ; Heterobranchus bidorsalis ; Nigeria ; Kainji L. ; Comparative study ; Bacteria ; Skin ; Clarias ; Heterobranchus ; Kainji Lake ; freshwater environment ; automation
    Repository Name: AquaDocs
    Type: conference_item , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 119-122
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  • 8
    Publication Date: 2022-05-27
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gosselin, K. M., Nelson, R. K., Spivak, A. C., Sylva, S. P., Van Mooy, B. A. S., Aeppli, C., Sharpless, C. M., O’Neil, G. W., Arrington, E. C., Reddy, C. M., & Valentine, D. L. Production of two highly abundant 2-methyl-branched fatty acids by blooms of the globally significant marine cyanobacteria Trichodesmium erythraeum. ACS Omega, 6(35), (2021): 22803–22810, https://doi.org/10.1021/acsomega.1c03196.
    Description: The bloom-forming cyanobacteria Trichodesmium contribute up to 30% to the total fixed nitrogen in the global oceans and thereby drive substantial productivity. On an expedition in the Gulf of Mexico, we observed and sampled surface slicks, some of which included dense blooms of Trichodesmium erythraeum. These bloom samples contained abundant and atypical free fatty acids, identified here as 2-methyldecanoic acid and 2-methyldodecanoic acid. The high abundance and unusual branching pattern of these compounds suggest that they may play a specific role in this globally important organism.
    Description: This work was funded with grants from the National Science Foundation grants OCE-1333148, OCE-1333162, and OCE-1756254 and the Woods Hole Oceanographic Institution (IR&D). GCxGC analysis made possible by WHOI’s Investment in Science Fund.
    Keywords: Lipids ; Alkyls ; Bacteria ; Genetics ; Chromatography
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 9
    Publication Date: 2017-04-04
    Description: Balanced information and education are fundamental prerequisites for risk prevention and preparedness. Among others, children embody our best chance to implant appropriate behaviors that will be recalled during hazardous situations and to involve adults according to a knowledge chain reaction. In this work, scientists challenge their communication skills to built a set of hands-on and learn-by-play based laboratory activities, for primary and secondary schools, addressing three major issues: (1) the location of earthquakes and volcanoes on Earth; (2) earthquakes and eruptions mechanisms; (3) earthquakes unpredictability. Students are asked to place volcanoes and earthquakes epicenters (issue 1) on a wooden plate puzzle according to Plate dynamics. To addresses eruption mechanisms (issue 2) and related hazard, we use backing soda forced blowing out from a volcano vent and suggest that a pyroclastic flow is fast, it can spread over a large area and raise high up to the stratosphere. Earthquake mechanisms (issue 2) are discussed describing the energy buildup, release, and transfer, using a wooden sticks bendand- break analogy. The display of acoustic waves caused by the breakage in different situations allows understanding of both the rupture energy and the wave attenuation. Earthquakes occurrence (issue 3) is addressed using steadily pulled blocks sliding on a frictional surface, where pins simulate asperities. These activities were tested, involving thousands of students. Discussions with students and teachers and the analysis of the answers to specific questionnaires gave us confidence that we proposed proper tools to raise risk awareness
    Description: Published
    Description: 89-93
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: restricted
    Keywords: Seismic and volcanic hazards, Outreach, Education ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 10
    Publication Date: 2020-02-24
    Description: In 2011 a research project on volcanic risk assessment at La Réunion Island (Project Aléa, Institute de Physique du Globe de Paris, France) was conducted in order to determine more efficient strategies to manage future volcanic crises. The project included the evaluation of volcanic scenarios through field and historical data analysis, as well as a survey on volcanic risk perception in resident population. A clear scientific information and an effective communication with public play a crucial role in risk mitigation strategies. In particular, the evaluation of the public perception during both volcanic crises and dormant periods is an important element in developing actions focused on specific social and cultural contexts. A questionnaire was developed based on the ones used in similar researches conducted on Italian active volcanoes. Items were designed to measure variables connected with personal perception of hazard and risk, trust in mitigation actions and in information received about these aspects. In addition, specific items related to the peculiarities of La Réunion Island environment were included. A total of 2,000 questionnaires were distributed taking into account factors such as the proximity to the volcano and the involvement of communities in recent volcanic emergencies. Main results coming out from this survey, if on the one hand show an adequate residents’ perception of natural hazards, on the other hand highlight their poor knowledge of the island’ active volcano, a similar lacking knowledge of emergency plan for volcanic crises, but also a high confidence in scientists to provide accurate and reliable information on volcanic risk and hazards in contrast with Local Authorities. Remarkable findings of this study assess some key elements that should be considered by the institutions in charge for defining policies aimed to volcanic risk mitigation and management of future volcanic crises.
    Description: Unpublished
    Description: 1V. Storia e struttura dei sistemi vulcanici
    Description: reserved
    Keywords: risk perception, volcanic hazards ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 11
    Publication Date: 2017-04-04
    Description: This book is one out of 8 IAEG XII Congress volumes, and deals with education and the professional ethics, which scientists, regulators, and practitioners of engineering geology inevitably have to face through the purposes, methods, limitations, and findings of their works. This volume presents contributions on the professional responsibilities of engineering geologists; the interaction of engineering geologists with other professionals; recognition of the engineering geological profession and its particular contribution to society, culture, and economy; and implications for the education of engineering geologists at tertiary level and in further education schemes. Issues treated in this volume are: the position of engineering geology within the geo-engineering profession; professional ethics and communication; resource use and re-use; managing risk in a litigious world; engineering and geological responsibility; and engineering geology at tertiary level. The Engineering Geology for Society and Territory volumes of the IAEG XII Congress held in Torino from September 15-19, 2014, analyze the dynamic role of engineering geology in our changing world and build on the four main themes of the congress: Environment, processes, issues, and approaches.
    Description: Published
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 5A. Energia e georisorse
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: open
    Keywords: Geoethics ; Geoeducation ; Professional Ethics ; Engineering Geology ; Communication ; Society ; Risks management ; Georesources ; Geological responsibility ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book
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  • 12
    Publication Date: 2017-04-04
    Description: The defence against natural hazards involves many actors with different roles: geoscientists, decision makers, local authorities, mass media, citizens. A proper management of georisks requires that each role is well-defined and governed by shared operational protocols, especially during the emergency phase, so that overlapping and misunderstanding don’t jeopardize population safety and economic activities. To achieve good results in this direction, it is necessary to undertake a careful evaluation of the limits and expectations of each component of society and the respect of legitimate aspirations and prerogatives. An effective defence system against natural hazards should be planned rationally and based on scientific data, in order to avoid alarmism among citizens, misleading sensationalism by media, careless decisions by politicians, as well as approximation in managing different phases of the risk cycle. Taking into consideration geoethical aspects related to natural hazards can be helpful to make geoscientists aware of their responsibilities towards society and to clarify the role they can play in the interaction with other actors, aiming at more efficacious actions for georisk mitigation.
    Description: Published
    Description: 59-62
    Description: 4T. Fisica dei terremoti e scenari cosismici
    Description: 4V. Vulcani e ambiente
    Description: 4A. Clima e Oceani
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: restricted
    Keywords: Geoethics ; Natural hazards ; Risks ; Society ; Responsibility ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 13
    Publication Date: 2020-02-24
    Description: The communication process between the geoscientists and native communities in risk areas can significantly affect disaster prevention and land use planning. In Peru, the problem of disaster prevention is a fundamental policy due to unfamiliarity and deficiency of the associate information on the population. It is possible that talk of disaster prevention it will be an unlikely ideal in a country where most towns have settled on unplanned projects by the constant change and the lack of interest from the authorities in such topics. However, it is anachronistic that the rural communities and towns continue to live without a plan to enable them to improve their quality of life. The correct use of geoscience information in the mass media can help in this work. The characteristics of the enterprise in Peru require more training by professionals in the geosciences and support communication specialists. In this paper, we analyze the problem of communication for disaster prevention in Peru, with the aim of contributing to the articulation of a disaster prevention strategy.
    Description: Published
    Description: 81-83
    Description: 3T. Pericolosità sismica e contributo alla definizione del rischio
    Description: 4V. Vulcani e ambiente
    Description: 6A. Monitoraggio ambientale, sicurezza e territorio
    Description: reserved
    Keywords: Communication process ; Disaster prevention ; Risk management ; Peru ; Geoethics ; 04. Solid Earth::04.06. Seismology::04.06.11. Seismic risk ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 14
    Publication Date: 2020-10-26
    Description: One of the main objectives of the ITACA (ITalian ACcelerometric Archive) strong motion database, promoted by the Italian Department of Civil Protection, was to improve the characterization of the recording sites from a geological and geophysical point of view and to provide their seismic classification according to the seismic norms pertinent to Italy, namely the Eurocode 8 and the National Technical Norms for Constructions. A standard format to summarize the available information for the recording stations was first produced, in terms of a technical report dynamically linked to the database, i.e., some of the relevant information is automatically updated when the corresponding fields of the database are modified. Then, an important activity of collection, qualification and synthesis of available data was carried out, especially for stations that recorded the strongest earthquakes in Italy in the last 40 years, and for which a relevant number of studies have been published. In spite of this activity, among the more than 700 strong motion stations present in the ITACA database, only a limited number of them could be characterized by quantitative information on subsurface soil properties. For this reason, a dual seismic site classification criterion was implemented, either based on the standard Vs,30 scheme, or, in the absence of such information, based on an expert opinion supported by shallow geology maps, mostly at 1:100,000 scale, and when available on the H/V ratios calculated on recordings. Owing to the relevance in the Italian geographic and morphological context, a special care was also given to the topographic classification of stations, based on suitable criteria developed within a GIS environment.
    Description: Published
    Description: 1779-1796
    Description: 4.1. Metodologie sismologiche per l'ingegneria sismica
    Description: JCR Journal
    Description: open
    Keywords: ITACA database ; Strong motion station ; General characterization ; Site classification ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion ; 04. Solid Earth::04.06. Seismology::04.06.06. Surveys, measurements, and monitoring ; 05. General::05.02. Data dissemination::05.02.02. Seismological data ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 15
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    Springer
    Publication Date: 2017-04-04
    Description: Previous research works proved the existence of a synchronization between speech and holds in adults and in 9 year old children with a rich linguistic vocabulary and advanced language skills. When and how does this synchrony develop during child language acquisition? Could it be observed also in children younger than 9? The present work aims to answer the above questions reporting on the analysis of narrations produced by three different age groups of Italian children (9, 5 and 3 year olds). Measurements are provided on the amount of synchronization between speech pauses and holds in the three different groups, as a function of the duration of the narrations. The results show that, as far as the reported data concerns, in children, as in adults, holds and speech pauses are to a certain extent synchronized and play similar functions, suggesting that they may be considered as a multi-determined phenomenon exploited by the speaker under the guidance of a unified planning process to satisfy a communicative intention. In addition, considering the role that speech pauses play in communication, we speculate on the possibility that holds may serve to similar purposes supporting the hypothesis that gestures as speech are an expressive resource that can take on different functions depending on the communicative demand. While speech pauses are likely to play the role of signalling mental activation processes aimed at replacing the “old spoken content” of the communicative plan with a new one, holds may signal mental activation processes aimed at replacing the “old visible bodily action” with new ones reflecting the representational and/or propositional contribution of gestures to the new communicative plan.
    Description: Published
    Description: 252-272
    Description: 5.9. Formazione e informazione
    Description: restricted
    Keywords: Speech pauses, holds, synchrony, child narrations ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: book chapter
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  • 16
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    Istituto Nazionale di Geofisica e Vulcanologia
    Publication Date: 2017-04-04
    Description: This is the first volume of an international scientific journal that is dedicated to issues of geoethics and geological culture. Its goal is to inform the Italian and international scientific communities about what emerged at the GeoItalia 2011 conference, attended by not only Italian geoscientists. At this conference, the geoscientists questioned their role in society and the responsibilities that they have to assume as scholars of the planet Earth and experts of the territory. They highlighted the need for rediscovery of the cultural values of geology as a science that can contribute to the construction of correct social knowledge, and the need to be aware that geoethics cannot exist without a real awareness among geoscientists of the cultural value of the Earth sciences.
    Description: Published
    Description: 331
    Description: 5.9. Formazione e informazione
    Description: JCR Journal
    Description: open
    Keywords: Geoethics ; Geoetica ; Geological Culture ; Earth Sciences ; Philosophy ; Education ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 17
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    Istituto Nazionale di Geofisica e Vulcanologia
    Publication Date: 2017-04-04
    Description: Prof. Giulio Giorello is amongst the most prominent philosophers of science in Italy and in the world. He is currently Professor of the Philosophy of Science at the University of Milan, Director of the Series ‘Science and Ideas’ (Raffaele Cortina Books Editor), and Literary Journalist of the cultural pages of the Corriere della Sera, one of the most important of the Italian newspapers. In this keynote presentation, in interview form, he talks about the value that the Earth sciences have had through history, framing this group of disciplines in ethical and epistemological terms, and highlighting some important elements that have to be considered in geological activities.
    Description: Published
    Description: 343-346
    Description: 5.9. Formazione e informazione
    Description: JCR Journal
    Description: open
    Keywords: Geoethics ; Geological Culture ; Geoetica ; Giulio Giorello ; Earth Sciences ; Interview ; Philosophy ; Epistemology ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 18
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    Istituto Nazionale di Geofisica e Vulcanologia
    Publication Date: 2017-04-04
    Description: The international debate in the field of geoethics focuses on some of the most important environmental emergencies, while highlighting the great responsibilities of geoscientists, whatever field they work in, and the important social, cultural and economic repercussions that their choices can have on society. The GeoItalia 2009 and 2011 conferences that were held in Rimini and Turin, respectively, and were organized by the Italian Federation of Earth Science, were two important moments for the promotion of geoethics in Italy. They were devoted to the highlighting of how, and with what tools and contents, can the geosciences contribute to the cultural renewal of society. They also covered the active roles of geoscientists in the dissemination of scientific information, contributing in this way to the correct construction of social knowledge. Geology is culture, and as such it can help to dispel misconceptions and cultural stereotypes that concern natural phenomena, disasters, resources, and land management. Geological culture consists of methods, goals, values, history, ways of thinking about nature, and specific sensitivity for approaching problems and their solutions. So geology has to fix referenced values, as indispensable prerequisites for geoethics. Together, geological culture and geoethics can strengthen the bond that joins people to their territory, and can help to find solutions and answers to some important challenges in the coming years regarding natural risks, resources, and climate change. Starting from these considerations, we stress the importance of establishing an ethical criterion for Earth scientists, to focus attention on the issue of the responsibility of geoscientists, and the need to more clearly define their scientific identity and the value of their specificities.
    Description: Published
    Description: 335-341
    Description: 5.9. Formazione e informazione
    Description: JCR Journal
    Description: open
    Keywords: Geoethics ; Education ; History of science ; Public issues ; General (Philosophy of Earth sciences) ; 04. Solid Earth::04.04. Geology::04.04.99. General or miscellaneous ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 19
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    Istituto Nazionale di Geofisica e Vulcanologia
    Publication Date: 2017-04-04
    Description: Franco Ferrarotti, Professor emeritus at ‘La Sapienza’ University of Rome; since winning the first Chair in this discipline in Italy in 1961, he has been considered the Father of Italian Sociology. An independent Member of Italian Parliament in the third government (1958-1963), a member of the New York Academy of Sciences, and a ‘visiting Professor’ at many universities in Europe, North America, Russia, Japan and Latin America. Franco Ferrarotti has taught and still teaches in Europe and America, and he has received many awards throughout his career. In this interview, he talks about the social aspects and consequences of Earth sciences studies.
    Description: Published
    Description: 347-348
    Description: 5.9. Formazione e informazione
    Description: JCR Journal
    Description: open
    Keywords: Geoethics ; Geological Culture ; Geoetica ; Social aspects ; Geologists activity ; Scientific information ; Society ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 20
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    Istituto Nazionale di Geofisica e Vulcanologia
    Publication Date: 2017-04-04
    Description: We argue here that the introduction of an ethical code of conduct that follows the example of the Hippocratic Oath of physicians will help geologists to acquire binding awareness of their professional and social responsibilities. The ethical behavior and obligations of modern geologists involve, but are not limited to, the following issues: correct land/ environment use and management; respect of truth and science; and protection of the Earth systems, on both the local and global scales, and therefore, of our well-being. We believe that for geoligists, the explicit acceptance of an ethical code will help to promote: (i) an awareness of their social role, expertise and sense of belonging to a professional community; (ii) an understanding of the expectations of citizens and society; and (iii) cultural growth, with better use of research and implementation of scientific and professional skills. All this should enhance the public recognition of the social mission of geologists, which is essential for the well-being of society. Therefore, we suggest that like in the majority of medical schools, ethical training should be a part of the university curriculum for students in geology.
    Description: Published
    Description: 365-369
    Description: 5.9. Formazione e informazione
    Description: JCR Journal
    Description: open
    Keywords: Geoethics ; Geological Culture ; Geoetica ; Hippocratic Oath ; Geologists ; Social responsibility ; 05. General::05.03. Educational, History of Science, Public Issues::05.03.99. General or miscellaneous ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 21
    Publication Date: 2022-05-26
    Description: © The Authors 2009. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License. The definitive version was published in Functional & Integrative Genomics 10 (2010): 97-110, doi:10.1007/s10142-009-0142-y.
    Description: Bacteria of the genus Shewanella can thrive in different environments and demonstrate significant variability in their metabolic and ecophysiological capabilities including cold and salt tolerance. Genomic characteristics underlying this variability across species are largely unknown. In this study, we address the problem by a comparison of the physiological, metabolic, and genomic characteristics of 19 sequenced Shewanella species. We have employed two novel approaches based on association of a phenotypic trait with the number of the trait-specific protein families (Pfam domains) and on the conservation of synteny (order in the genome) of the trait-related genes. Our first approach is top-down and involves experimental evaluation and quantification of the species’ cold tolerance followed by identification of the correlated Pfam domains and genes with a conserved synteny. The second, a bottom-up approach, predicts novel phenotypes of the species by calculating profiles of each Pfam domain among their genomes and following pair-wise correlation of the profiles and their network clustering. Using the first approach, we find a link between cold and salt tolerance of the species and the presence in the genome of a Na+/H+ antiporter gene cluster. Other cold-tolerance-related genes include peptidases, chemotaxis sensory transducer proteins, a cysteine exporter, and helicases. Using the bottom-up approach, we found several novel phenotypes in the newly sequenced Shewanella species, including degradation of aromatic compounds by an aerobic hybrid pathway in Shewanella woodyi, degradation of ethanolamine by Shewanella benthica, and propanediol degradation by Shewanella putrefaciens CN32 and Shewanella sp. W3-18-1.
    Description: This research was supported by the U.S. Department of Energy (DOE) Office of Biological and Environmental Research under the Genomics: GTL Program via the Shewanella Federation consortium.
    Keywords: Phenotypic trait ; Bacteria ; Molecular mechanisms of cold tolerance ; Shewanella ; Protein families
    Repository Name: Woods Hole Open Access Server
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  • 22
    Publication Date: 2017-04-04
    Description: Red Pompeian paintings, very famous for their deep intensity, are currently suffering from darkening. The origins of this darkening degradation are not clearly identified yet and remain a major issue for curators. In the specific case of cinnabar (HgS)-based red pigment, a photoinduced conversion into black metacinnabar is usually suspected. This work is focused on the blackening of red cinnabar paintings coated on a sparry calcite mortar. Different samples exhibiting different levels of degradation were selected upon visual observations and analyzed by synchrotron-based microanalytical techniques. Atomic and molecular compositions of the different debased regions revealed two possible degradation mechanisms. On one hand, micro X-ray fluorescence elemental maps show peculiar distributions of chlorine and sulfur. On the other hand, X-ray absorption spectroscopy performed at both Cl and S K-edges confirms the presence of characteristic degradation products: (i) Hg- Cl compounds (e.g., corderoite, calomel, and terlinguaite), which may result from the reaction with exogenous NaCl, in gray areas; (ii) gypsum, produced by the calcite sulfation, in black coatings. Metacinnabar is never detected. Finally, a cross section was analyzed to map the in-depth alteration gradient. Reduced and oxidized sulfur distributions reveal that the sulfated black coating consists of a 5-ím-thick layer covering intact cinnabar.
    Description: Published
    Description: 7484-7492
    Description: reserved
    Keywords: Microspectroscopy Analysis ; 05. General::05.09. Miscellaneous::05.09.99. General or miscellaneous
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  • 23
    ISSN: 1433-4909
    Keywords: Key words Extreme thermophile ; Thermosipho ; Thermotogales ; Deep-sea hydrothermal vent ; Bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A novel barophilic, extremely thermophilic bacterium was isolated from a deep-sea hydrothermal vent chimney at the Iheya Basin, in the Okinawa area, Japan. The cells were found to be rod shaped and surrounded by a sheath-like outer structure; the organism did not possess flagella and was not motile. Growth was observed between 45° and 80°C (optimum, 72°C, 45 min doubling time), pH 5.3 and 9.3 (optimum, pH 7.2–7.6), 6.6 and 79 g/l sea salts (optimum, 40 g/l), and 0.1 and 60 MPa (optimum, 20 MPa). Strain IHB1 was found to be a strictly anaerobic chemoorganotroph capable of utilizing yeast extract and proteinaceous substrates such as peptone and tryptone. Elemental sulfur or thiosulfate acted as electron acceptors improving growth. The isolate was able to utilize casein as a sole carbon and energy source in the presence of thiosulfate. The G + C content of the genomic DNA was 31.4 mol%. Phylogenetic analysis based on 16S rDNA sequences and DNA–DNA hybridization analysis indicated that the isolate is closely related to Thermosipho africanus; however, it represents a species distinct from the previously described members of the genus Thermosipho. On the basis of the physiological and molecular properties, we propose that the new isolate represents a new species, which we name Thermosipho japonicus sp. nov. (type strain: IHB1; JCM10495).
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  • 24
    ISSN: 1432-0789
    Keywords: Keywords Aggregate stability ; Bacteria ; Burnt soil ; Compost ; Fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The restoration of soil microbial activities is a basic step in the reclamation of burnt soils. For this reason, the ability of municipal solid waste compost to accelerate the re-establishment of bacterial and fungal populations, as well as to re-establish physical properties in a burnt soil, was evaluated in a field experiment. Four treatments were performed by adding different doses of compost (0, 0.5, 1 and 2 kg compost m–2 soil) to a burnt Calcic Rodoxeralf soil, and the changes in microbial populations, salt content, aggregate stability and bulk density were evaluated for 1 year. Initially, the addition of compost had a negative effect on soil microbial populations, but 3 months after compost addition, the number of viable fungal propagules increased in all the amended soils. This positive effect lasted until the end of the experiment. From 30 days onwards, all the amended soils showed a greater total number of bacterial cell forming units than the unamended burnt soil. Organic amendment increased the percentage of 2- to 4-mm aggregates, although the effect on the stability of the 0.2- to 2-mm aggregates and on bulk density was less noticeable.
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  • 25
    ISSN: 1432-1211
    Keywords: Key words Vβ13 ; CD4/CD8 ratio ; Rat ; Tcrb ; Polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Three rat BV13S1 alleles (T-cell receptor β-chain variable gene 13) were characterized by new BV13S1-allele specific monoclonal antibodies (18B1 and 17D5) and sequence analysis of expressed and genomic BV13S1. Two alleles were functional and designated BV13S1A1 present in strains LEW, BUF, PVG, and BV13S1A2 present in BN and WF. Their products differed by six amino acids, two of them in complementarity-determing region (CDR)1 and one in CDR2. A third nonfunctional allele, BV13S1A3P, was found in strains F344 and DA. Apart from a single nucleotide insertion, it was identical to BV13S1A2. All 12 rat strains tested showed association of TCRBC1 with BV8S2/4 alleles but not with the BV13S1 alleles, which may reflect a different gene order of the rat BV compared to mouse. BV13S1A1-encoded T-cell receptors (TCRs) which bind both monoclonal antibody (mAb) 18B1 and mAb 17D5 are over-represented in the CD4 lymphocyte subset. BV13S1A2-encoded TCRs which are stained by mAb 18B1 but not by mAb 17D5 show a slight CD8-biased expression. Preferential usage of BV13S1A1-positive TCRs by CD4 but not by CD8 cells in (LEW×WF)F1 hybrids and cosegregation of BV13SA1 and increased frequency of BV13S1 TCR-positive CD4 cells in a (LEW×BN)×BN backcross suggest structural differences of the two allelic products as the reason for their contrasting CD4/CD8 subset bias.
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  • 26
    ISSN: 1432-119X
    Keywords: Endothelin-A receptor ; Endothelin-B receptor ; Rat ; Pulmonary fibrosis ; Immunohistochemistry ; Quantitative PCR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: AbstractPulmonary fibrosis is characterized by excessive extracellular matrix deposition with concomitant loss of gas exchange units, and endothelin-1 (ET-1) has been implicated in its pathogenesis. Increased levels of ET-1 from tissues and bronchoalveolar lavage have been reported in patients with pulmonary fibrosis and in animal models after intratracheal bleomycin. We characterized the cellular distribution of alveolar ET receptors by immunohistochemistry in bleomycin-induced pulmonary fibrosis in the rat and determined the regulation by bleomycin of ET receptor mRNA expression in isolated alveolar macrophages and rat lung fibroblasts. We found significant increases in the numbers of fibroblasts and macrophages at day 7 compared to day 28 and control animals. ETB receptor immunoreactivity was observed on fibroblasts and invading monocytes. Isolated fibroblasts expressed both ETA and ETB receptor mRNA, and ETA receptor mRNA was upregulated by bleomycin. Isolated resident alveolar macrophages expressed neither ETA nor ETB receptor mRNA which were also not induced by bleomycin. We conclude that, while ETB receptor stimulation of fibroblasts and monocytes recruited during bleomycin-induced lung injury exerts antagonistic effects on fibroblast collagen synthesis, the observed increase in the number of fibroblasts in vivo and upregulation of fibroblast ETA receptor mRNA by bleomycin in vitro point to a predominance of the profibrotic effects of ET receptor engagement.
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  • 27
    ISSN: 1432-2021
    Keywords: Key words Cristobalite ; Tridymite ; Phase transformation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Using minimum exposure techniques, it is feasible to perform high resolution electron microscopy on the α-cristobalite phase of (Si0.9 Ge0.1)O2, which is extremely radiation sensitive. Such images reveal atomic scale information of twins and tridymite-like stacking faults on (1 1 1)β planes, as well as of domain boundaries resulting from the β→α transition. Polytype structures are formed in certain cases. Morphological features suggest that the phase transformation cristobalite → tridymite proceeds by means of a zonal dislocation mediated synchro-shear process on (1 1 1)β planes; the geometry of this process is analyzed.
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  • 28
    ISSN: 1432-1017
    Keywords: Key words X-ray crystallography ; Electron microscopy ; Biological databases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Advances in structural biology are opening greater opportunities for understanding biological structures from the cellular to the atomic level. Particularly promising are the links that can be established between the information provided by electron microscopy and the atomic structures derived from X-ray crystallography and nuclear magnetic resonance spectroscopy. Combining such different kinds of structural data can result in novel biological information on the interaction of biomolecules in large supramolecular assemblies. As a consequence, the need to develop new databases in the field of structural biology that allow for an integrated access to data from all the experimental techniques is becoming critical. Pilot studies performed in recent years have already established a solid background as far as the basic information that an integrated macromolecular structure database should contain, as well as the basic principles for integration. These efforts started in the context of the BioImage project, and resulted in a first complete database prototype that provided a versatile platform for the linking of atomic models or X-ray diffraction data with electron microscopy information. Analysis of the requirements needed to combine data at different levels of resolution have resulted in sets of specifications that make possible the integration of all these different types in the context of a web environment. The case of a structural study linking electron microscopy and X-ray data, which is already contained within the BioImage data base and in the Protein Data Bank, is used here to illustrate the current approach, while a general discussion highlights the urgent need for integrated databases.
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  • 29
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    Physics and chemistry of minerals 27 (2000), S. 480-494 
    ISSN: 1432-2021
    Keywords: Key words Olivine ; Grain boundary ; Partial melt ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The microstructure of olivine-olivine grain boundaries has been studied in experimentally deformed (1200–1227 °C, 300 MPa) partially molten olivine and olivine-orthopyroxene rocks. In-situ melting produced ∼1 vol% melt in all samples studied. Grain boundary analyses were carried out using a number of transmission electron microscopy techniques. The grain boundary chemistry in undeformed olivine-orthopyroxene starting material showed evidence for the presence of an intergranular phase along some, but not all, of the olivine-olivine boundaries. In the deformed samples, ultrathin Si-rich, Al- and Ca-bearing amorphous films have been observed along all investigated olivine-olivine grain boundaries. The chemistry of the grain boundaries, which is considered to be indicative for the presence of a thin film, was measured with energy-dispersive X-ray spectroscopy (EDX) and energy-filtering imaging. The amorphous nature of the films was confirmed with diffuse dark field imaging, Fresnel fringe imaging, and high-resolution electron microscopy. The films range in thickness from 0.6 to 3.0 nm, and EDX analyses show that the presence of Al and Ca is restricted to this ultrathin film along the grain boundaries. Because thin melt films have been observed in all the samples, they are thought to be stable features of the melt microstructure in deformed partially molten rocks. The transition from the occasional presence of films in the undeformed starting material to the general occurrence of the films in deformed materials suggests that deformation promotes the formation and distribution of the films. Alternatively, hot-pressing may be too short for films to develop along all grain boundaries. A difference in creep strength between the studied samples could not be attributed to grain boundary melt films, as these have been found in all deformed samples. However, a weakening effect of grain boundary melt films on olivine rheology could not be ruled out due to the lack of confirmed melt-film free experiments.
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  • 30
    ISSN: 1619-0904
    Keywords: Poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (MPC) ; In vivo biocompatibility ; Artificial endocrine pancreas ; Electron microscopy ; Glucose sensor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Biocompatibility is important to assure a mild body reaction to an implanted device and its long-term stability and functionality. In diabetes research, subcutaneously implanted glucose monitoring systems need biocompatible surfaces for long-term application. The biocompatibility of poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (MPC), a material similar to the phospholipid layer of a cell membrane, was compared in vivo with the biocompatibility of polyurethane (PU), polyvinyl alcohol (PVA), and cuprophane (CUP). Needle-type glucose sensors and hollow-fiber probes used for microdialysis were coated with these four different biomaterials and implanted subcutaneously in 18 rats and 7 healthy volunteers. At set intervals, the implants and, in the case of the rats, also the surrounding tissue were removed and characterized by light and electron microscopy. MPC-coated sensors and hollow-fiber probes showed smooth and thin deposits in flat layers, whereas the surface deposits on PU- and PVA-coated sensors and those on CUP hollow-fiber probes appeared as rough, irregular, and dense attachments of aggregated cells and protein. This study confirmed results from earlier in vitro tests by showing the biocompatibility and reliability of MPC. Even though the amount of protein and cells attached to the MPC surface was not as low as expected from in vitro experiments, the biocompatibility and long-term stability of the implanted devices were superior to those of PU, PVA, and CUP.
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  • 31
    ISSN: 1615-6102
    Keywords: Electron microscopy ; Photoreceptor ; Visual membrane ; Photic radiation damage ; Retina ; Crustacea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Visual membranes of the crayfish eye either belong to the small, distally placed rhabdomere of retinula cell R8 or are part of the much more voluminous proximal rhabdom, made up of rhabdomeres belonging to cells R1–R7. Under various conditions of environmental stress (e.g., prolonged darkness, elevated temperature, bright light with and without a concomitant rise in temperature, flickering lights) the visual membranes of R8 prove far more resistant to structural damage than those of R1–R7. Membrane damage is known to occur when dormant lipoxygenases become activated, for example through heat. Since R8 is the only type of visual cell in the crayfish retina that does not contain grains of screening pigment, the view that screening-pigment granules could “aggravate” or even “trigger” membrane damage in times of stress is strengthened. Functionally, R8's strong resistance to physical damage when exposed to flickering lights points to a role of the distal rhabdom in the movement detection system of the crayfish eye.
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  • 32
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    Annals of biomedical engineering 28 (2000), S. 128-134 
    ISSN: 1573-9686
    Keywords: Hippocampus ; Vigilance states ; Paired-pulse ; Dentate gyrus ; Dentate granule cells ; Evoked response ; Rat ; In vivo studies ; Perforant path ; Maturation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract This study examined the effect of normal development and vigilance state on the modulation of dentate granule cell activity in the freely moving rat at 15, 30, and 90 days of age across three vigilance states: quiet waking, slow-wave sleep, and rapid eye movement sleep. Using paired-pulse stimulation, the paired-pulse index (PPI) was obtained for the dentate evoked field potentials elicited by the stimulation of the medial perforant path. Although significant differences in PPI values were observed during development, no significant vigilance state related changes were obtained. Preweaning infant rats, i.e., 15-day old, exhibited significantly less early (interpulse intervals, IPI= 20–50 ms) and late (IPI = 300–1000 ms) inhibition, and less facilitation (IPI = 50–150 ms) when compared to the 90-day old adult rats during all three vigilance states. PPI values obtained from the 30-day old group fell intermediate between the 15- and 90-day old animals. These changes in PPI values provide a quantitative measure of changes in the modulation of dentate granule cell excitability during normal maturation. They can now can be used to evaluate the impact of various insults, such as prenatal protein malnutrition or neonatal stress, on hippocampal development. © 2000 Biomedical Engineering Society. PAC00: 8717Nn, 8719La, 8719Nn
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  • 33
    ISSN: 1573-9686
    Keywords: Heart ; Left ventricle ; LV contractility ; ESPVR ; Pig ; Rat ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract The end systolic pressure–volume relation (ESPVR) has been shown to be a relatively load independent measure of left ventricular (LV) contractility. Recently, several single-beat ESPVR computation methods have been developed, enabling the quantification of LV contractility without the need to alter vascular loading conditions on the heart. Using a single-beat ESPVR method, which has been validated previously in humans and assumes that normalized elastance is constant between individuals of a species, we studied the effects of myocardial infarction on LV contractility in two species, the rat and the pig. In our studies, LV pressure was acquired invasively and LV volume determined noninvasively with magnetic resonance imaging, at one week postinfarction in pigs and at 12 weeks postinfarction in rats. Normalized systolic elastance curves in both animal species were not statistically different from that of humans. Also, the slope of the ESPVR $$\left( {E_{es} } \right)$$ decreased significantly following infarction in both species, while the volume-axis intercept $$\left( {V_0 } \right)$$ was unaffected. These results indicate that a single-beat ESPVR method can be used to measure the inotropic response of the heart to myocardial infarction, and that the basis for this method (i.e., constant normalized elastance) is applicable to a variety of mammalian species. © 2000 Biomedical Engineering Society. PAC00: 8719Uv, 8761Lh, 8719Hh, 8719Rr, 8719Ff
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  • 34
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    Annals of biomedical engineering 28 (2000), S. 1101-1115 
    ISSN: 1573-9686
    Keywords: Time–frequency analysis ; Coherence ; Cross correlation ; Nonstationary persistent signals ; Central pattern generator ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract We present a novel time-varying phase spectrum (TVPS) method to quantify the dynamics of coevolution of two persistent nonstationary coupled signals. Based on the TVPS, an instantaneous intersignal phase shift is defined within the primary frequency range in which the two signals are highly correlated. The TVPS is estimated using a fixed-window method or an adaptive-window method. In the latter method, the window length changes dynamically and automatically as a function of change in frequency of the signals. The effects of altering window types and lengths on the accuracy of the estimation of the primary phase shift is assessed by analyzing synthesized linear chirp signals with decaying amplitude and constant relative phase shift or decaying amplitude and changing relative phase shifts. The methods developed are also used for determining the evolution of the primary phase shift among ventral root activities during fictive locomotion in an in vitro rat spinal cord preparation. The analyses indicate that the TVPS method in conjunction with the determination of the primary frequency range, allows determination of both the evolution of the coupling strength and the evolution of the phase shift between two persistent nonstationary rhythmic signals in the joint time–frequency domain. An adaptive window reduces the estimation bias and the estimation variability. © 2000 Biomedical Engineering Society. PAC00: 0230-f, 8780Tq
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  • 35
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    Antonie van Leeuwenhoek 77 (2000), S. 117-133 
    ISSN: 1572-9699
    Keywords: Archaea ; Bacteria ; hydrothermal vents ; in situ hybridization ; molecular ecology ; probes ; 16S rRNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The study of the structure and diversity of hydrothermal vent microbial communities has long been restricted to the morphological description of microorganisms and the use of enrichment culture-based techniques. Until recently the identification of the culturable fraction required the isolation of pure cultures followed by testing for multiple physiological and biochemical traits. However, peculiar inhabitants of the hydrothermal ecosystem such as the invertebrate endosymbionts and the dense microbial mat filaments have eluded laboratory cultivation. Substantial progress has been achieved in recent years in techniques for the identification of microorganisms in natural environments. Application of molecular approaches has revealed the existence of unique and previously unrecognized microorganisms. These have provided fresh insight into the ecology, diversity and evolution of mesophilic and thermophilic microbial communities from the deep-sea hydrothermal ecosystem. This review reports the main discoveries made through the introduction of these powerful techniques in the study of deep-sea hydrothermal vent microbiology.
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  • 36
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    Journal of comparative physiology 170 (2000), S. 531-535 
    ISSN: 1432-136X
    Keywords: Key words Large intestine ; Furrow of proximal colon ; Digesta ; Bacteria ; Soft and hard feces ; Nutrias ; Myocastor coypus ; AbbreviationsN nitrogen ; TAA total amino acids ; DAP diaminopimelic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The bacterial level of soft feces is higher than that of hard feces in nutrias. This suggests the heterogeneity of bacterial density in the large intestine. To show the heterogeneity of bacteria in the contents of the large intestine in nutrias, we divided the contents of the large intestine into 12 regions, then measured the nitrogen (N), total amino acids (TAA) and diaminopimelic acid (DAP), a bacterial marker, of these regions. Levels of N, TAA and DAP varied along the cross section of the proximal colon. The greater curvature of the main lumen and furrow had higher N, TAA and DAP concentrations than the lesser curvature. We also examined the involvement of the furrow in producing two types of feces differing in bacterial nitrogen content by surgically preventing the flow of the furrow contents. We compared the concentrations of N, TAA and DAP between soft and hard feces among operated, sham-operated and intact animals. Surgical closure of the furrow abolished the difference in levels of N, TAA and DAP between soft and hard feces, suggesting that the furrow of the proximal colon is responsible for making the bacterial density higher in soft feces than in hard feces.
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  • 37
    ISSN: 0219-1032
    Keywords: c-Fos ; Dopamine ; D1 ; Hippocampus ; Rat ; Synaptic Plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract While dopamine is likely to modulate hippocampal synaptic plasticity, there has been little information about how dopamine affects synaptic transmission in the hippocampus. The expression of IEGs including c-fos has been associated with late phase LTP in the CA1 region of the hippocampus. The induction of c-fos by dopaminergic receptor activation in the rat hippocampus was investigated by using semiquantitative RT-PCR and immuno-cytochemistry. The hippocampal slices which were not treated with dopamine showed little expression of c-fos mRNA. However, the induction of c-fos mRNA was detected as early as 5 min after dopamine treatment, peaked at 60 min, and remained elevated 5 h after treatment. Temporal profiles of increases in c-fos mRNA by R(+)-SKF-38393 (50 μM) and forskolin (50 μM) were similar to that of dopamine. An increase in [cAMP] was observed in dopamine-, SKF-, or forskolin-treated hippocampal slices. By immunocytochemical studies, control hippocampal cells showed little expression of c-Fos immunoreactivity. However, when cells were treated with dopamine, an increase in the expression of c-Fos immunoreactivity was observed after treatment for 2 h. The treatment of hippocampal neurons with R(+)-SKF38393 (50 μM) or forskolin (50 μM) also induced a significant increase in c-Fos expression. These results indicate that the dopamine D1 receptor-mediated cAMP dependant pathway is associated with the expression of c-Fos in the hippocampal neurons. These data are consistent with the possible role of endogenous dopamine on synaptic plasticity via the regulation of gene expression. Furthermore, these results imply that dopamine might control the process of memory storage in the hippocampus through gene expression.
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  • 38
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    World journal of microbiology and biotechnology 16 (2000), S. 495-497 
    ISSN: 1573-0972
    Keywords: Bacteria ; biodegradation ; 2,4-D ; soil microcosm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Bacterial isolates (NJ 10 and NJ 15) capable of degrading the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) were isolated from agricultural soil by enrichment culture technique. The isolates exhibited substantial growth in mineral salt medium supplemented with 0.1–0.5% of 2,4-D as a sole source of carbon and energy. Based on their morphological, cultural and biochemical characteristics, the isolates NJ 10 and NJ 15 have been identified as Pseudomonas species and Pseudomonas aeruginosa, respectively. Biodegradation studies in a soil microcosm enriched with pure cultures of the isolates demonstrated a time-dependent disappearance of 2,4-D from the 100 mg/kg herbicide-amended soil. The HPLC data analysis revealed 96.6 and 99.8% degradation in the soil inoculated with the pure cultures of isolates NJ 10 and NJ 15, respectively with in 20 days of incubation at 30 °C. Both the isolates showed significant solubilization of inorganic phosphate [Ca3(PO4)2] on the specific Pikovskaya's medium.
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  • 39
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    World journal of microbiology and biotechnology 16 (2000), S. 115-134 
    ISSN: 1573-0972
    Keywords: Bacteria ; biocontrol ; biological control ; compost ; disease ; fungi ; microbiology ; pathogen ; suppression ; turf ; turfgrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The relationships among the chemical, physical and biological aspects of compost and their role in suppression of turfgrass pathogens are reviewed. The composting process, mediated by microbial activity, is affected by physical and chemical characteristics which include temperature, aeration, moisture content, C:N ratio and pH. In the absence of parameter restrictions, the microbial community follows a predictable successional pattern resulting in the re-colonization of compost with metabolically active mesophilic populations that can be suppressive towards plant pathogens. Although mechanisms of suppression are not fully understood, those postulated include physiochemical and biological characteristics. The physiochemical characteristics of composts can alter suppressive properties through direct effects on pathogens and antagonistic microorganisms, or indirect effects on host systems through the supply of nutrients, improvement of soil structure, porosity and water retention capabilities, along with other factors. Biological characteristics centre on microbial community involvement in suppressive mechanisms, which can include one or a combination of competition for nutrients, antibiosis, lytic and other extracellular enzyme production, parasitism, predation and host-mediated induction of resistance. As a result of the potential benefits of compost, there is considerable interest in determining the capacity for composts to suppress turfgrass pathogens. Although the exact mechanisms of suppression are largely unknown, there appear to be several factors that play an integrated role. The use of composts that successfully suppress turfgrass diseases will permit a reduction in the use of chemical controls, and slow the development of fungicide resistance.
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  • 40
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    Medical & biological engineering & computing 38 (2000), S. 42-48 
    ISSN: 1741-0444
    Keywords: Bowel sounds ; Rat ; Motility ; Body acoustics ; Signal detection ; Signal characterisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract This study is aimed at detecting gastrointestinal sounds (GIS) and correlating their characteristics with gastrointestinal (GI) conditions. The central hypotheses are that GIS generation depends on the motility patterns and the mechanical properties of the gut, and that changes in those result in measurable differences in GIS. An animal model which included both healthy rats and those with small bowel obstruction (SBO) was developed. The acoustic bursts, of GIS were detected by amplitude thresholding the signal envelope. Three methods of envelope estimation were proposed and evaluated. Envelope estimation using a Hilbert transform was found to produce the best results in the current application. The duration and dominant frequency of each detected GIS event was estimated and clear differences between healthy and diseased rats were discovered. In the control state, GIS events were found to consistently be of relatively short duration (3–65ms). Although the majority of events in the SBO state had similar short duration, infrequent longer events were also detected and appeared to be pathognomonic. Long duration events (〉100 ms) occurred in each of seven obstructed, but in none of 14 non-obstructed, cases (p〈0.001). It is concluded that GIS analysis may prove useful in the non-invasive, rapid, and accurate diagnosis of SBO.
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  • 41
    ISSN: 1432-0789
    Keywords: Key words Grasslands ; Management ; Microbial biomass ; Bacteria ; Fungi ; Nitrogen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  There is much interest in the development of agricultural land management strategies aimed at enhancing reliance on ecosystem self-regulation rather than on artificial inputs such as fertilisers and pesticides. This study tested the usefulness of measures of soil microbial biomass and fungal:bacterial biomass ratios as indicators of effective conversion from an intensive grassland system, reliant mainly on fertilisers for crop nutrition, to a low-input system reliant mainly on self-regulation through soil biological pathways of nutrient turnover. Analysis of soils from a wide range of meadow grassland sites in northern England, along a gradient of long-term management intensity, showed that fungal:bacterial biomass ratios (measured by phospholipid fatty acid analysis; PLFA) were consistently and significantly higher in the unfertilised than the fertilised grasslands. There was also some evidence that microbial biomass, measured by chloroform fumigation and total PLFA, was higher in the unfertilised than in the fertilised grasslands. It was also found that levels of inorganic nitrogen (N), in particular nitrate-N, were significantly higher in the fertilised than in the unfertilised grasslands. However, microbial activity, measured as basal respiration, did not differ between the sites. A field manipulation trial was conducted to determine whether the reinstatement of traditional management on an improved mesotrophic grassland, for 6 years, resulted in similar changes in the soil microbial community. It was found that neither the cessation of fertiliser applications nor changes in cutting and grazing management significantly affected soil microbial biomass or the fungal:bacterial biomass ratio. It is suggested that the lack of effects on the soil microbial community may be related to high residual fertility caused by retention of fertiliser N in the soil. On the basis of these results it is recommended that following the reinstatement of low-input management, the measurement of a significant increase in the soil fungal:bacterial biomass ratio, and perhaps total microbial biomass, may be an indicator of successful conversion to a grassland system reliant of self-regulation.
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  • 42
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    Biology and fertility of soils 29 (1999), S. 170-177 
    ISSN: 1432-0789
    Keywords: Key words Chitin degradation ; Succession ; Fungi ; Bacteria ; Actinomycetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The dynamics of culturable chitin-degrading microorganisms were studied during a 16-week incubation of chitin-amended coastal dune soils that differed in acidity. Soil samples were incubated at normal (5% w/w) and high (15% w/w) moisture levels. More than half of the added chitin was decomposed within 4 weeks of incubation in most soils. This rapid degradation was most likely due to fast-growing chitinolytic fungi (mainly Mortierella spp. and Fusarium spp.) at both moisture levels, as dense hyphal networks of these fungi were observed during the first 4 weeks of incubation. Chitin N mineralization was inhibited by cycloheximide, and fast-growing fungal isolates were capable of rapid chitin decomposition in sterile sand, further suggesting that these fungi play an important role in initial chitin degradation. The strong increase in fast-growing fungi in chitin-amended dune soils was only detected by direct observation. Plate counts and microscopic quantification of stained hyphae failed to reveal such an increase. During the first part of the incubation, numbers of unicellular chitinolytic bacteria also increased, but their contribution to chitin degradation was indicated to be of minor importance. During prolonged incubation, colony forming units (CFU) of chitinolytic streptomycetes and/or slow-growing fungi increased strongly in several soils, especially at the 5% moisture level. Hence, the general trend observed was a succession from fast-growing fungi and unicellular bacteria to actinomycetes and slow-growing fungi. Yet, the composition of chitinolytic CFU over time differed strongly between chitin-amended dune soils, and also between the two moisture levels. These differences could not be attributed to pH, organic matter or initial microbial composition. The possible consequence of such unpredictable variation in microbial community composition for the use of chitin-amendments as a biocontrol measure is discussed.
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  • 43
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    Biology and fertility of soils 28 (1999), S. 431-435 
    ISSN: 1432-0789
    Keywords: Key words Actinomycetes ; Bacteria ; Cynodon spp. ; Fungi ; Turfgrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Four natural organic fertilizers, alone or in combination with the synthetic organic fertilizer isobutylidene diurea (IBDU), were compared with IBDU alone for their effect on soil/root microbial populations associated with bermudagrass grown on a golf course putting green in southern Florida, USA. Populations of total fungi, total bacteria, fluorescent pseudomonads, Stenotrophomonas maltophilia, actinomycetes and heat-tolerant bacteria were monitored every 3 months during the 2-year study. On only one sampling date and for only one bacterial population (S. maltophilia) was a significant difference in microbial populations obtained among the fertilizer treatments. However, the S. maltophilia populations associated with the natural organic fertilizer treatments were not significantly different from the synthetic organic IBDU fertilizer treatment.
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  • 44
    ISSN: 1437-3262
    Keywords: Key words Carbonates ; Cold seeps ; Methane ; Petroleum ; Archaea ; Bacteria ; Sponges ; Tube worms ; Epifluorescence ; Biomarkers ; Jurassic ; Tertiary ; France ; Italy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The relation of two well-known ancient carbonate deposits to hydrocarbon seepage was confirmed by this study. Archaea are found to be associated with the formation of Oxfordian seep carbonates from Beauvoisin and with a Miocene limestone from Marmorito ("tube-worm limestone"). Carbonates formed due to a mediation by archaea exhibit extremely positive or extremely negative δ13Ccarbonate values, respectively. Highly positive values (+15‰) reflect the use of 13C-enriched CO2 produced by methanogenesis. Low δ13C values of the Marmorito carbonates (–30‰) indicate the oxidation of seepage-derived hydrocarbons. Likewise, the δ13C content of specific tail-to-tail linked isoprenoids, biomarkers for archaea, was found to be strikingly depleted in these samples (as low as –115‰). The isotopic signatures corroborate that archaea were involved in the cycling of seepage-derived organic carbon at the ancient localities. Another Miocene limestone ("Marmorito limestone") shows a strong imprint of methanotrophic bacteria as indicated by δ13C values of carbonate as low as –40‰ and biomarker evidence. Epifluorescence microscopy and field-emission scanning electron microscopy revealed that bacterial biofilms were involved in carbonate aggregation. In addition to lucinid bivalves previously reported from both localities, we infer that sponges from Beauvoisin and tube worms from Marmorito depended on chemosynthesis as well. Low δ13C values of nodules related to sponge taphonomy (–27‰) indicate that sponges might have been linked to an enhanced hydrocarbon oxidation. Tube worm fossils from Marmorito closely resemble chemosynthetic pogonophoran tube worms from Recent cold seeps and are embedded in isotopically light carbonate (δ13C –30‰).
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  • 45
    ISSN: 1432-1211
    Keywords: Key words Class II MHC sequence ; Rat ; Cloning ; RT-PCR ; Polymorphism
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    Topics: Biology , Medicine
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  • 46
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    European biophysics journal 28 (1999), S. 263-267 
    ISSN: 1432-1017
    Keywords: Key words Human liver ; Human brain ; Ferritin ; Electron microscopy ; Mössbauer spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Human brain (globus pallidus) and liver tissues were investigated by means of electron microscopy (EM), Mössbauer spectroscopy (MS) and SQUID magnetometry techniques. Based on MS measurements, the iron present was identified to be in the ferritin-like form (61–88%) and in the form of a low-spin iron species (the balance). Its overall concentration was estimated as 1.5(3) mg in the brain and 2.4(5) mg in the liver, per gram of lyophilized tissue. The average core diameter was determined by EM measurements to be equal to 7.5(1.3) nm for the liver and 3.3(5) nm for the brain. Magnetization measurements carried out between 5 and 300 K yielded an estimation of an average blocking temperature, KT BL, as equal to 6.7 K and 8.5 K for the liver and the brain, respectively. From the dependence of KT BL on the external magnetic field it was concluded that the ferritin-like cores in the studied samples can be regarded as non-interacting particles. Finally, the uniaxial magnetic anisotropy constant was determined to be 6×103 J/m3 for the liver and 4×104 J/m3 for the brain.
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  • 47
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    Archives of microbiology 172 (1999), S. 213-218 
    ISSN: 1432-072X
    Keywords: Key words 16S rRNA gene sequences ; Phylogeny ; Bacteria ; Archaea ; Brines ; Kebrit Deep ; Red Sea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this study, we report on first 16S rRNA gene sequences from highly saline brine sediments taken at a depth of 1,515 m in the Kebrit Deep, northern Red Sea. Microbial DNA extracted directly from the sediments was subjected to PCR amplification with primers specific for bacterial and archaeal 16S rRNA gene sequences. The PCR products were cloned, and a total of 11 (6 bacterial and 5 archaeal) clone types were determined by restriction endonuclease digestion. Phylogenetic analysis revealed that most of the cloned sequences were unique, showing no close association with sequences of cultivated organisms or sequences derived from environmental samples. The bacterial clone sequences form a novel phylogenetic lineage (KB1 group) that branches between the Aquificales and the Thermotogales. The archaeal clone sequences group within the Euryarchaeota. Some of the sequences cluster with the group II and group III uncultivated archaea sequence clones, while two clone groups form separate branches. Our results suggest that hitherto unknown archaea and bacteria may thrive in highly saline brines of the Red Sea under extreme environmental conditions.
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  • 48
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    Journal of mathematical biology 38 (1999), S. 359-375 
    ISSN: 1432-1416
    Keywords: Key words: Chemotaxis ; Partial differential equations ; Bacteria ; Mathematical Modeling ; Pattern formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract.  A variety of spatial patterns are formed chemotactically by the bacteria Escherichia coli and Salmonella typhimurium. We focus in this paper on patterns formed by E. coli and S. typhimurium in liquid medium experiments. The dynamics of the bacteria, nutrient and chemoattractant are modeled mathematically and give rise to a nonlinear partial differential equation system. We present a simple and intuitively revealing analysis of the patterns generated by our model. Patterns arise from disturbances to a spatially uniform solution state. A linear analysis gives rise to a second order ordinary differential equation for the amplitude of each mode present in the initial disturbance. An exact solution to this equation can be obtained, but a more intuitive understanding of the solutions can be obtained by considering the rate of growth of individual modes over small time intervals.
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  • 49
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    Cell & tissue research 296 (1999), S. 235-246 
    ISSN: 1432-0878
    Keywords: Key words Transplantation ; Parkinson’s disease ; CNS fetal development ; CNS differentiation ; Neurotrophic factors ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We have previously shown that a combination of the cytokines interleukin (IL)-1, IL-11, leukemia inhibitory factor (LIF), and glial cell line-derived neurotrophic factor (GDNF) can convert rat fetal (E14.5) mesencephalic progenitor cells into tyrosine hydroxylase (TH)-immunoreactive (ir) neurons in vitro. The experiments described here characterize the mesencephalic progenitor cells and their cytokine-induced conversion into dopamine (DA) neurons. For all experiments, we used bromodeoxyuridine (BrdU)-ir cultures of (E14.5) mesencephalic progenitor cells that had been expanded at least 21 days. We first demonstrated that IL-1 induced DA neuron conversion in mesencephalic progenitors, but not in striatal progenitors (P〈0.001). Thus, these cells should be classified as lineage-restricted progenitors, and not omnipotent stem cells. To further characterize cell populations in these cultures, we used monoclonal antibodies against Hu (an early marker for neurons), growth-associated protein (GAP)-43 (a marker for neuronal process extension), TH (a marker for DA neurons), and glial fibrillary acidic protein (GFAP, a marker for astrocytes). We assessed (E14.5) mesencephalic progenitor cell cultures (plated at 125,000 cells/cm2) incubated in the cytokine mixture (described above) or in complete media (CM, negative control). Following 7 days incubation, GFAP-positive cells formed a nearly confluent carpet in both types of cultures. However, numbers of Hu-ir and GAP-43-ir cells in the cytokine-incubated cultures far exceeded those in CM-incubated controls (P=0.0003, P=0.0001, respectively), while numbers of TH-ir cells were 58-fold greater in the cytokine-incubated cultures versus CM-incubated controls. The TH phenotype persisted for 7 days following withdrawal of the differentiation media. Numerous double-labeled cells that were BrdU-ir and also TH-ir, or Hu-ir and also TH-ir, were observed in the cytokine-incubated cultures. These data suggest that cytokines ”drive” the conversion of progenitor cells into DA neurons.
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  • 50
    ISSN: 1432-0878
    Keywords: Key words Subcommissural organ ; Isograft ; Xenograft ; Reissner’s fiber ; Cerebrospinal fluid ; Rat ; Bovine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The subcommissural organ (SCO) secretes glycoproteins into the cerebrospinal fluid (CSF) that aggregate and form Reissner’s fiber (RF). The factors involved in this aggregation are not known. One factor may be the hydrodynamics of the CSF when flowing through the aqueduct. This hypothesis was tested by isografting rat SCO and xenografting bovine SCO into the lateral ventricle of rats. Xenografts were either fresh bovine SCO or explants cultured for 30 days before transplantation. The grafts were investigated by electron microscopy and immunocytochemistry using antibodies against RF glycoproteins, serotonin and the glucose transporter I. Maximal time of transplantation was 43 days for isografts and 14 days for xenografts. The isografts were not reinnervated but were revascularized; they secreted into the ventricle RF glycoproteins that became progressively packed into pre-RF and RF structures identical to those formed by the SCO in situ. RF was confined to the host ventricle and at its distal end the constituent proteins disassembled. Xenografts were neither reinnervated nor revascularized and secreted into the host ventricle a material that never formed an RF. These findings indicate that the CSF factor responsible for the formation of RF is species specific, and that this process does not depend on the hydrodynamics of the CSF. The blood vessels revascularizing the isografted SCO acquired the characteristics of the vessels irrigating the SCO in situ, namely, a tight endothelium displaying glucose transporter I, and a perivascular space containing long-spacing collagen, thus indicating that basal release of glycoproteins may also occur in the grafted SCO.
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  • 51
    ISSN: 1432-0878
    Keywords: Key words Descending contralateral movement detector (DCMD) ; Identified neuron ; Vesicles ; Electron microscopy ; 3-D reconstruction ; Locust ; Schistocercagregaria (Insecta)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The descending contralateral movement detector (DCMD), an identified descending interneuron in the brain of the locust Schistocerca gregaria has been investigated by using light and electron microscopy. We describe the fine structure, distribution and numbers of synapes that it receives from another identified brain neuron, the lobular giant movement detector (LGMD), and from unidentified neurons. The DCMD dendrites emerging from the integrative segment vary in form and number between individuals and sexes but always form a flattened dendritic domain. The arborizations and the integrative segment appear to be exclusively postsynaptic. Two types of synaptic contacts (Type 1 and 2) onto the DCMD can be discerned as having either round (Type 1) or pleiomorphic synaptic vesicles (Type 2) and by large (Type 1) or small (Type 2) subsynaptic appositions. Contact zones of Type 1 synapses are smaller than those of Type 2. LGMD-synapses are of Type 1 and occur intermingled with presynaptic sites of unidentified units. Some branches of the DCMD receiving input from unidentified units are devoid of contacting LGMD processes. Synapses of both types are randomly distributed over the DCMD integrative segment and at fibres with similar sizes.Type 1 synapses are much more frequent than Type 2 synapses and their number is negatively correlated with fibre diameter. For a whole DCMD dendritic arborization, a total of 8500 active zones of chemical synapses has been calculated, including a mininum of 2250 LGMD-synapses and about 1000 Type 2 synapses. The DCMD may thus receive a considerable amount of input from as yet unidentified neurons.
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  • 52
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    Cell & tissue research 296 (1999), S. 359-369 
    ISSN: 1432-0878
    Keywords: Key words Apoptosis ; Electron microscopy ; Meiosis ; Spermatocytes ; Spermatogenesis ; Testis ; TUNEL ; Mouse (10 strains)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Apoptosis of male germ cells is a widespread but little-understood phenomenon in many animal species. The elucidation of its mechanisms could be useful in the understanding of male infertility. We have examined the distribution of dying cells with the terminal transferase-mediated nick-end labeling (TUNEL) method and by an electron-microscopic procedure in the testes of 10 mouse strains, viz., C57BL/10 (B10), SL/NiA (SL), C57BL/6 (B6), C3H/He (C3H), BALB/c (BALB), DBA2 (DBA), CBA/J (CBA), MRL/MpJ-+/+ (M+), MRL/MpJ-lpr/lpr (lpr), and wild-type NJL mice (Mus musculus musculus). In the testes of the B10, NJL, SL, B6, C3H, BALB, DBA, and CBA mice, very few TUNEL-positive cells are distributed in the seminiferous tubules, whereas in the testes of the M+ and lpr mice, many TUNEL-positive cells, which are restricted to stage XII seminiferous tubules, have been identified. The most important finding is that many metaphases of meiotic spermatocytes show a marked TUNEL-positive reaction. Some metaphases show apoptotic morphology electron-microscopically. These results suggest that the testes of MRL strains will provide a useful model for the study of the mechanism of metaphase-specific apoptosis in meiotic spermatocytes.
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  • 53
    ISSN: 1432-0878
    Keywords: Key words Axonal transport ; Purkinje cell ; Organotypic culture ; Microinjection ; Antimitotic drugs ; Cytoskeleton ; Dendritic transport ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Axonal and dendritic transport in single Purkinje neurons of cerebellar slice cultures was quantified as single transport distances. Examination of the cells within a vital tissue was regarded as being an approach to the in situ condition. The Purkinje cells were organotypically integrated in the in vitro tissues and extended long axonal projections connecting synapses to the target neurons. The tracer horseradish peroxidase (HRP) was applied via microinjection to the somata of the Purkinje cells and the injected neurons were incubated thereafter for defined time-intervals. The tracer was transported anterogradely into the neuron processes. The measurements on both the axonal and the dendritic transport of microinjected HRP revealed continuous transportation with increasing times of postincubation. This transport was reduced by the use of microtubule-depolymerizing drugs. The axonal transport of the tracer was either retarded in colchicine-treated cells or continuously reduced for up to 50% in vinblastine-treated neurons. Thus, a correlation of axonal transport to the microtubules was demonstrated. The dendrites were filled with the tracer after 60 min of postincubation. Dendritic transport was reduced by the use of vinblastine, and not significantly by colchicine. The results strongly support the dependence of neuronal transport on microtubules as a component of the cytoskeleton.
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  • 54
    ISSN: 1432-0878
    Keywords: Key words Neurofilament ; Basket cell ; Pinceau ; Golgi apparatus ; Calcium binding protein ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract NCS-1 (neuronal calcium sensor) is a recently characterized member of a highly conserved neuron-specific family of calcium-binding proteins, which also includes frequenin and recoverin. The cellular and subcellular distributions of NCS-1 in the rat nervous system were investigated using light- and electron-microscopic immunohistochemistry. NCS-1 immunoreactivity was localized to neuronal cell bodies and axons throughout the brain and spinal cord but not to glial cells. The most intense labeling was observed in myelinated axons, the axonal ramifications of the basket cell in the cerebellar cortex, and large neurons in the brainstem and pons. These same structures were also characterized by heavy labeling for neurofilament protein, as determined by double-labeling experiments. Most axon terminals were unlabeled or only lightly labeled. The most remarkable subcellular staining occurred in the perikarya where intense labeling was associated with the membranes of the trans saccules of the Golgi apparatus. The widespread distribution of NCS-1 indicates that it may be active in a variety of calcium-dependent neuronal functions, whereas the specific subcellular localization to the Golgi apparatus and neurofilament-rich structures suggests a specialized role in calcium regulated protein trafficking and cytoskeletal interactions.
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  • 55
    ISSN: 1432-0878
    Keywords: Key words Neuromelanin ; Neuron ; Peroxidase ; Oxygen metabolism ; High-definition light microscopy ; Electron microscopy ; Ultrastructure ; Cytochemistry ; Substantia nigra ; Lumbricusterrestris (Annelida)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Histochemical examination of 1-μm tissue sections from the dorsal nerve plexus of the earthworm, Lumbricus terrestris, reveals multiple brown intraneuronal granules. These granules contain material morphologically and histochemically consistent with neuromelanin. When viewed with transmission electron microscopy, these were seen as single membrane-enclosed biphasic granules with diameters of 370–730 nm. Exposure of L. terrestris to high-level environmental oxygen resulted in an increase in the number of neuromelanin-like pigment granules within the neurons of the circular muscle layer. As measured by ortho-phenylenediamine hydrochloride, the endogenous peroxidase activity of extracts from worms incubated in high-level environmental oxygen was 51% more than controls. The endogenous peroxidase activity was localized in situ with 3,3-diaminobenzidine (DAB) and was found to increase in and around the neuromelanin-like pigment-containing neurons within the circular muscle layer. These studies suggest that the nerve net of L. terrestris may serve as a model to study the role of neuromelanin production in oxidative stress and its relationship to endogenous peroxidases.
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  • 56
    ISSN: 1432-0878
    Keywords: Key words Glial cell line-derived neurotrophic factor ; GDNF ; Ret ; GDNFR-α ; Brain-derived neurotrophic factor ; BDNF ; NT-3 ; NT-4 ; trk receptors ; Thyroid tissue ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Levels of mRNA for neurotrophins (brain-derived neurotrophic factor, BDNF; neurotrophin 3, NT-3; neurotrophin 4, NT-4) and their receptors (trkA, trkB, trkC) and for glial cell line-derived neurotrophic factor (GDNF) and its receptors (ret, GDNFR-α) were measured in rat thyroid tissue by ribonuclease protection assays. In thyroid tissue the NT-3 mRNA level was threefold lower and the NT-4 mRNA level sixfold higher than those detected in adult rat hippocampus, while BDNF mRNA was undetectable. Very low levels of mRNA for truncated trkB and trkC receptors and no catalytic trkA, trkB or trkC were found. In conclusion NT-3 and NT-4, but not the corresponding functional receptors, are expressed in the thyroid tissue. Therefore, it is unlikely that these factors serve a direct local autocrine or paracrine function in thyroid cell types, and a target-derived mode of action on neurons innervating the thyroid tissue is suggested. An opposite result has been found for the neurotrophic factor GDNF: thyroid tissue showed a high level of transcripts for the GDNF receptor subunits (GDNFR-α and Ret), while GDNF mRNA was undetectable. The in situ hybridization analysis of GDNFR-α and ret mRNA revealed an interesting difference in the cell distribution of these transcripts: ret mRNA is selectively expressed in a subpopulation of cells scattered in the follicular epithelium and in the interfollicular spaces, while GDNFR-α expression is more homogeneous and widespread, including the more abundant cell type of the thyroid gland: the follicular cell. Double-labeling in situ hybridization/immunocytochemistry experiments, with a specific marker (calcitonin), showed that parafollicular cells express ret but not GDNFR-α. This differential distribution of the GDNF receptor components (GDNFR-α and ret) may reflect a peculiar biological role in intercellular communication in the thyroid gland.
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  • 57
    ISSN: 1432-0878
    Keywords: Key words Immunohistochemistry ; Electron microscopy ; Interstitial cells of Cajal ; F4/80 ; CSF-1 ; Kit-receptor ; Mouse (op/op)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The osteopetrotic (op/op) mutant mouse possesses an inactivating mutation in the colony-stimulating factor-1 (CSF-1) gene, which results in the absence of certain macrophages and in osteopetrosis, following a lack of osteoclasts. Studies of the op/op mouse indicate that CSF-1-dependent tissue macrophages may belong to a trophic and/or scavenger subpopulation, which through their effect on other cell types can significantly affect tissue functions, and that cells which are CSF-1 independent have antigen presentation and immunological functions.We have previously identified a cell system of regularly distributed macrophages in the muscularis externa of the small intestine and wanted to extend these studies to the op/op mouse.The present investigations with light- and electron-microscopic methods using fluorescent dextran, methylene blue and immunohistochemistry (F4/80, anti-kit receptor, anti-CD3, anti-CD45R/B220) show that macrophages are absent from the muscle layers, with only an occasional macrophage present in the subserosa. In the lamina propria and submucosa, macrophage numbers are reduced. In all other respects the muscularis externa appears normal, including normal organization and number of interstitial cells of Cajal. Control and op/op mice both lack cells expressing CD3 (T lymphocytes), CD45R/B220 (B lymphocytes) and mast cells in the muscularis externa. This leaves the muscularis externa macrophages as the most likely source of local cytokine production under such conditions as postoperative ileus and intussusception in infants, where the muscularis externa appears to be one target of cytokines. We conclude that the lack of macrophages, combined with the preservation of otherwise normal structure, will make the op/op mouse a valuable model by which to assess the functions and relative importance of the muscularis externa macrophages in relation to intestinal motility under normal and pathological conditions.
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  • 58
    ISSN: 1432-0878
    Keywords: Key words Water channel protein ; Aquaporin ; AQP5 ; Rat ; Salivary glands ; Immunolocalization ; Secretory stimulation ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Aquaporin-5 (AQP5) is a water channel protein and is considered to play an important role in water movement across the plasma membrane. We raised anti-AQP5 antibody and examined the localization of AQP5 protein in rat salivary and lacrimal glands by immunofluorescence microscopy. AQP5 was found in secretory acinar cells of submandibular, parotid, and sublingual glands, where it was restricted to apical membranes including intercellular secretory canaliculi. In the submandibular gland, abundant AQP5 was also found additionally at the apical membrane of intercalated duct cells. Upon stimulation by isoproterenol, apical staining for AQP5 in parotid acinar cells tended to appear as clusters of dots. These results suggest that AQP5 is one of the candidate molecules responsible for the water movement in the salivary glands.
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  • 59
    ISSN: 1432-0878
    Keywords: Key words Caveolin ; Caveolae ; Lung ; Alveolar epithelial type I cell ; Immunocytochemistry ; Electron microscopy ; Confocal laser scanning microscopy ; Rat (CD)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Caveolae are flask-shaped invaginations of the plasmalemma which pinch off to form discrete vesicles within the cell cytoplasm. Biochemically, caveolae may be distinguished by the presence of a protein, caveolin, that is the principal component of filaments constituting their striated cytoplasmic coat. Squamous alveolar epithelial type I (ATI) cells, comprising approximately 95% of the surface area of lung alveolar epithelium, possess numerous plasmalemmal invaginations and cytoplasmic vesicles ultrastructurally indicative of caveolae. However, an ultrastructural appearance does not universally imply the biochemical presence of caveolin. This immunocytochemical study has utilised a novel application of confocal laser scanning and electron microscopy unequivocally to localise caveolin-1 to ATI cells. Further, cytoplasmic vesicles and flask-shaped membrane invaginations in the ATI cell were morphologically identified whose membranes were decorated with anti-caveolin-1 immunogold label. Coexistent with this, however, in both ATI and capillary endothelial cells could be seen membrane invaginations morphologically characteristic of caveolae, but which lacked associated caveolin immunogold label. This could reflect a true biochemical heterogeneity in populations of morphologically similar plasmalemmal invaginations or an antigen threshold requirement for labelling. The cuboidal alveolar epithelial type II cell (ATII) also displayed specific label for caveolin-1 but with no ultrastructural evidence for the formation of caveolae. The biochemical association of caveolin with ATI cell vesicles has broad implications for the assignment and further study of ATI cell function.
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  • 60
    ISSN: 1573-739X
    Keywords: Stability ; Buprenorphine ; Glycopyrrolate ; Haloperidol ; Polypropylene ; Polyvinyl chloride ; PVC ; Syringes ; Cassettes ; Bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Combinations of opioids and adjuvant drug solutions are often used in clinical practice while little information is available on their microbiological or chemical stability. Currently there are no commercially available, prepacked, ready‐to‐use epidural or subcutaneous mixtures. Thus, epidural and subcutaneous analgesic mixtures must be prepared in the pharmacy on an as‐needed basis. Such mixtures are typically used for the treatment of severe pain in cancer patients. The aim of this study was to investigate the microbiological and chemical stability of a buprenorphine, haloperidol and glycopyrrolate mixture in a 0.9% sodium chloride solution. A high performance liquid chromatographic (HPLC) method and pH‐meter were used to conduct the analyses. Antimicrobial activity of each component was studied by an agar dilution method. According to the results from the chemical and microbiological stability studies, this mixture can be stored in polypropylene (PP) syringes and polyvinyl chloride (PVC) medication cassettes for at least 30 days at either 21 °C or 4 °C, and for 16 days in PP syringes at 36 °C, and for 9 days in PVC medication cassettes at 36 °C.
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  • 61
    ISSN: 1573-9104
    Keywords: Bioavailability ; Magnesium ; Hijiki ; Sodium alginate ; Rat ; Wakame
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The bioavailability of magnesium from Wakame and Hijiki, and the effects of alginic acid on absorption of dietary magnesium were examined in five groups of rats fed either control, Wakame, Hijiki, AW (containing the same amount of alginate as in the Wakame) and AH (containing the same amount of alginate as in the Hijiki) diets, and animals fed a low magnesium diet (LMg) (twentieth amount of magnesium in the original mineral mixtures as the control). Food intake and body weight gain were decreased by adding sodium alginate to the diets. A large amount of calcium accumulated only in the kidneys of the rats fed the LMg diet. Serum magnesium concentration decreased only in the LMg group. The magnesium content in the defatted left femurs did not differ between the control and Wakame fed animals and also among the animals eating Wakame, Hijiki and AW diets. The breaking force of the right femurs did not differ among all the groups except the LMg group. The ratio of apparent magnesium absorption (%) of the control, LMg, Wakame, Hijiki, AW and AH groups was 82.2, 72.7, 66.9, 50.8, 69.3 and 54.2 in the first experimental period, and was 75.3, 52.1, 57.7, 46.9, 62.6 and 60.5 in the second experimental period, respectively. It was clear that the bioavailability of magnesium in the Wakame fed rats was higher than in those eating the Hijiki. Large amounts of sodium alginate lowered magnesium absorption from the diet.
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  • 62
    ISSN: 1435-1536
    Keywords: Key words Double chain surfactants ; Aggregates ; Phase diagrams ; Lamellar phases ; Electron microscopy ; SANS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We present the phase diagrams and the properties of newly synthesised double-chain cationic N-alkyl-N-alkyl′-N,N-dimethylammonium bromide surfactants [C x C y DMABr (x = 12, 14 and 16; y = 10, 11, 12, 14 and 16)]. All the systems studied form liquid-crystalline lamellar phases but with different morphologies: unilamellar vesicles at low surfactant concentrations, multilamellar vesicles and tubular aggregates for surfactant concentrations between 2 and 10 wt% and at even higher concentrations planar bilayers of surfactant molecules in the classical Lα phase. The phase diagrams were determined with macroscopic and microscopic methods (polarisation microscopy, freeze-fracture transmission electron microscopy, scanning electron microscopy and differential interference contrast microscopy). The properties of the surfactant solutions were determined with differential scanning calorimetry measurements for Krafft point determination and small-angle neutron scattering measurements for interlamellar spacing and bilayer thickness. Finally, conductivity and viscosity measurements for phase characterisation were carried out.
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  • 63
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    Colloid & polymer science 277 (1999), S. 164-173 
    ISSN: 1435-1536
    Keywords: Keywords Nanostructures ; Thin films ; Vapor deposition ; Electron microscopy ; Optical properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Colloidal dispersions of Yb, Er and Pr have been prepared by chemical liquid deposition. The metals were cocondensed at 77 K with 2-methoxyethanol and ethanol to produce solvated metal atoms. The particle size of the dispersions was determined by transmission electron microscopy to range from 52 to 1080 Å; the particles had spherical shapes. After solvent evaporation under vacuum, active solids and amorphous powder were deposited over Cu and Al metal. Dispersion stability, particle size, UV/Vis absorption and zeta potential were studied. The solids prepared by solvent evaporation were characterized by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The films prepared on Al were studied by scanning electron microscopy. The most stable colloid was obtained using 2-methoxyethanol: several concentrations were stable for several months and the zeta potential indicated that this colloid stability is mainly due to solvation effects. FTIR spectroscopy of the solids indicated solvent incorporation in the film. This observation was corroborated by thermal analysis. Information on the thermal stability of the films was obtained by TGA. The UV/Vis absorption spectrum was measured at several concentrations under different conditions.
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  • 64
    ISSN: 1573-0603
    Keywords: Dichloromethylene diphosphate ; Hepatic stellate cell isolation ; Liposome ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hepatic perisinusoidal cell population consists of hepatic stellate cells, Kupffer cells, endothelial cells, and Pit cells. These cells are isolated by enzymic digestion and purified by density gradient centrifugation. With isolation of stellate cells, conventional method is unable to eliminate the contamination of Kupffer cells because the densities of these two cells are similar. We report here an improved method for isolation of highly purified hepatic stellate cells, using dichloromethylene diphosphate (CL2MDP), which has selective cytotoxicity of Kupffer cells. Three days after the single intravenous administration of liposome-encapsulated CL2MDP, the Kupffer cells disappeared almost completely from the liver. Following Percoll density gradient centrifugation, the purity of the hepatic stellate cells exceeded 98% without any contamination of the Kupffer cells. Kupffer cells are reported to affect the physiological functions of stellate cells. The availability of highly purified stellate cells will facilitate the investigation of their functions in primary culture.
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  • 65
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    World journal of microbiology and biotechnology 15 (1999), S. 7-10 
    ISSN: 1573-0972
    Keywords: Bacteria ; evolution ; molecular ; pairing ; recognition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract One principal function of biological molecules in bacteria is to recognize other molecules. This allows cells to assemble for regulated enzymatic catalysis and the integration of biochemical pathways. Recognition is also an essential and a specific property in base pairing of DNA in the double helix. Therefore, recognition events must have been central to early self-assembly of primitive genetic material, genomes, cells, genetic recombination and especially in enzyme-substrate-product recognition events. Molecular recognition events are examined with an emphasis on their central role in early prokaryotic evolution.
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  • 66
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    World journal of microbiology and biotechnology 15 (1999), S. 297-304 
    ISSN: 1573-0972
    Keywords: Bacteria ; cell ; diversity ; division ; Earth ; evolution ; metabolism ; self-assembly ; surfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract About 80% of the evolutionary history of life on Earth is restricted to microorganisms which have had several billion years to speciate. The reasons for the origin (self-assembly) of life on Earth, bacterial cell division and why there are so many different bacteria and their global dispersal are discussed from an evolutionary perspective.
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  • 67
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    World journal of microbiology and biotechnology 15 (1999), S. 1-6 
    ISSN: 1573-0972
    Keywords: Bacteria ; conjugation ; DNA ; evolution ; gene transfer ; transduction ; transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The transfer of genetic information by transformation, conjugation and transduction in bacteria occurs frequently in nature. These diverse gene transfer mechanisms in bacteria are the result of evolution and are not linked to reproduction as in eukaryotic organisms. In this review, gene transfer in bacteria will be considered from an evolutionary perspective.
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  • 68
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    Biology and fertility of soils 26 (1998), S. 313-322 
    ISSN: 1432-0789
    Keywords: Key words Fungi ; Bacteria ; Nitrogen ; Scots pine ; Stratification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The abundance and micro-stratification of bacteria and fungi inhabiting the organic layers of a Scots pine forest (Pinus sylvestris L.) were investigated. An experiment using stratified litterbags, containing organic material of four degradation stages (fresh litter, litter, fragmented litter and humus) was performed over a period of 2.5 years. Dynamics and stratification of fluorescent stained bacteria and fungi, ratios between bacterial and fungal biomass, and relationships with moisture and temperature are described. Average bacterial counts in litter and fragmented litter were similar, i.e., approximately 5×109 bacteriag–1 (dry weight) organic matter, and significantly exceeded those in humus. The mean bacterial biomass ranged from 0.338 to 0.252mg carbon (C) g–1 (dry weight) organic matter. Lengths of mycelia were significantly below the usually recorded amounts for comparable temperate coniferous forests. The highest average hyphal length, 53mg–1 (dry weight) organic matter, was recorded in litter and decreased significantly with depth. The corresponding mean fungal biomass ranged from 0.050 to 0.009mg Cg–1 (dry weight). The abundance of bacteria and fungi was influenced by water content, that of fungi also by temperature. A litterbag series with freshly fallen litter of standard quality, renewed bimonthly, revealed a clear seasonal pattern with microbial biomass peaks in winter. The mean hyphal length was 104mg–1 (dry weight) and mean number of bacteria, 2.40×109 bacteria g–1 (dry weight). Comparable bacterial and fungal biomass C were found in the freshly fallen litter [0.154 and 0.132mgCg–1 (dry weight) organic material, respectively]. The ratio of bacterial-to-fungal biomass C increased from 1.2 in fresh litter to 28.0 in humus. The results indicate the existence of an environmental stress factor affecting the abundance of fungi in the second phase of decomposition. High atmospheric nitrogen deposition is discussed as a prime factor to explain low fungal biomass and the relatively short lengths of fungal hyphae in some of the forest soil layers under study.
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  • 69
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    Biology and fertility of soils 27 (1998), S. 149-154 
    ISSN: 1432-0789
    Keywords: Key words Marigold ; Tagetes ; Rhizosphere ; Nematode suppression ; Bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Marigolds (genus Tagetes) suppress populations of soil endopathogenic nematodes such as Pratylenchus penetrans and Meloidogyne species. Nematode suppression by marigolds is thought to be due to thiophenes, heterocyclic sulfur-containing molecules abundant in this plant. When activated, thiophenes such as α-terthienyl produce oxygen radicals. If marigold roots release such a powerful biocidal agent and it is activated in soil, microbial populations in the marigold rhizosphere should be substantially perturbed. We made various measurements of microbial population size and activity in soils that had been cropped to marigolds (Crackerjack, Creole) in the field and in the greenhouse, and compared these with bare soil and soil cropped to rye (Secale cereale L.). Total extractable microbial biomass (measured by the fumigation extraction method), total bacteria (measured by epifluorescence microscopy on 5-(4,6-dichlorotriazine-2-γl) aminofluorescein-stained preparations), heterotrophic bacteria (measured by plate count on various media), and nitrite-oxidizing bacteria (measured by the most-probable-number method) were not significantly different in any of the treatments. Residues of 14C-labelled rye were mineralized slightly more rapidly in rye-cropped soil than in the other treatments, which were comparable. The rates of die-back of introduced cells of the bacteria Escherichia coli and Rhodococcus TE1 were similar in marigold-cropped and control soils, suggesting that there was not a noteworthy accumulation of biocidal agents in soils cropped to marigolds. We conclude that marigolds do not cause a general depression in the numbers of microorganisms in soils, and that nematode control by this plant may not be due to the release of a biocidal agent into the soil.
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  • 70
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    Biology and fertility of soils 26 (1998), S. 179-186 
    ISSN: 1432-0789
    Keywords: Key words Inoculation ; Bacteria ; Soil ; Community ; Changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of plant-growth-promoting rhizobacteria (PGPR) and spruce seedlings on the composition and activity of forest soil microbial communities was studied in a microcosm experiment in which sterile, sand-filled 25mm×150mm glass tubes were treated with a forest soil suspension containing Bacillus or Pseudomonas PGPR and 2-week-old spruce seedlings. Eighteen weeks after treatments were established, bacterial, actinomycete and fungal population sizes were determined by dilution plating, as were seedling dry weights and soil carbon substrate utilization profiles using Biolog plates. PGPR inoculation had little influence on the population sizes of actinomycetes or fungi. However, significant effects were detected on the total bacterial population size, primarily in microcosms without seedlings. Euclidean distances between treatments plotted on two dimensions by multidimensional scaling showed that the introduction of PGPR strains changed the type of microbial community, particularly when inoculated into soil without seedlings. Significant changes were also detected in one soil type in the presence of seedlings. Our results suggest that the type of soil community and the presence of seedlings are significant factors influencing the responses of soil communities to bacterial inoculation, and that for some soil communities, the presence of seedlings may mitigate perturbations caused by the introduction of PGPR.
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  • 71
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    Environmental geology 34 (1998), S. 257-269 
    ISSN: 1432-0495
    Keywords: Key words Colloids ; Particle size distribution ; Karstic aquifer ; Analytical techniques ; Bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Colloids are known to transport contaminants over long distances in natural media. Despite this potentially harmful effect, very few studies have been undertaken in subsurface aquifers. This paper presents the first results of a study of natural colloids and particles in a karstic aquifer. The site was chosen for its coverage by clay layers and peat which deliver various and numerous particle types in water. The methodological part describes three methods used for size determination and sample fractionation of surface water and spring water. These methods have been adapted for the treatment of multiple samples due to the rapid discharge variation typical of karstic aquifers. The analysis of many particle size distributions (PSD) shows that they can be described by a Pareto law. The variation of the slope of the PSD at the spring is mainly dependent on discharge. This behavior is interpreted as a washing of the karstic drains during the first phase of high flow events. Fractionation of the samples allowed application of various characterization techniques to particle size classes. X-ray diffraction (XRD) patterns showed that most of the mineral particles originated from Quaternary deposits and limestones. However the use of scanning electron micrsocopy with energy-dispersive spectrometer (SEM-EDS) detailed the composition of individual particles and revealed particles not found by XRD. These techniques also showed the high complexity of the natural particles and the important place of coprecipitation in their formation. Consequences on the fluxes of particulate matter and its potential role as a carrier of contaminants are discussed.
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  • 72
    ISSN: 1432-0495
    Keywords: Key words Transport ; Bacteria ; Iron ; Groundwater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Among the demonstrated processes influencing the transport of bacteria through aquifers, the deposition of cells on mineral surfaces is one of the most important. For example, understanding the transport of introduced bacteria through aquifers is essential to designing some in situ bioremediation schemes. The impact of the presence and distribution of Fe(III)-oxyhydroxide-coated sand grains on bacterial transport through porous media was evaluated in column experiments in which bacteria (short rods; 1.2 μm length) were eluted through columns of quartz sand (0.5–0.6 mm in diameter) for several conditions of chemical heterogeneity of mineral substrate. Fe(III)-oxyhydroxide-coated sand was present as 10% of the mass, and it was arranged in three treatments: (1) homogeneously distributed, and present as a discrete layer (2) at the top and (3) at the bottom of 14-cm-long sand columns. A pulse input of 108 cells ml–1 was introduced in an artificial groundwater solution flowing at 14 cm h–1 through the column, and eluted cells were counted. Peak breakthrough occurred at 1.0 pore volume. A large proportion of cells were retained; 14.7–15.8% of the cells were recovered after three pore volumes of solution had eluted through clean quartz sand, and only 2.1–4.0% were recovered from the Fe(III)-oxyhydroxide-coated sand mixtures. The three physical arrangements of the chemical heterogeneity resulted in essentially the same breakthrough of cells, indicating that the spatial distribution of iron coating does not affect the transport of bacteria. The results of the column transport experiments, which mimic hydrogeological conditions encountered in field problems, are consistent with our mechanistic understanding of bacterial sorption.
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  • 73
    ISSN: 1432-1211
    Keywords: Key words CD1 ; Rat ; Gene ; Organization ; Polymorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The non-major histocompatibility complex (MHC)-encoded CD1 family has recently emerged as a new antigen-presenting system that is distinct from either MHC class I or class II molecules. In the present study, we determined the genomic structure of the rat CD1 locus. It was extremely similar to mouse CD1 genes, especially to CD1D1. The 5′ flanking region of the CD1 gene contained the binding motifs for two cytokine-inducible transcription factors, NF-IL2-A and NF-IL6. Some regulatory elements found in MHC class I genes (enhancer A, enhancer B, and the IFN response element) were absent. It is of interest that a tyrosine-based motif for endosomal localization found in the human CD1b cytoplasmic tail was encoded by a single short exon which was conserved in all CD1 molecules except for CD1a. Southern blot and direct sequencing analyses of inbred rat strains suggested very limited polymorphism in the 5′ region where a hydrophobic ligand-binding groove is encoded; a single base substitution resulted in amino acid alteration of alanine (GCT) to valine (GTT) at codon 119. Comparison of the overall exon-intron organization of CD1 genes revealed that the length of the intron was also characteristic to each of the two classes of CD1 genes, classic CD1 and CD1D; such categorization has hitherto been made according to the sequence similarity of the coding region. This finding provides further support for the hypothesis that the two classes have different evolutionary histories. In contrast to the complete absence of the classic CD1 in rats and mice, the entire region of nonpolymorphic CD1D has been conserved through mammalian evolution. Similar functional properties of rodent CD1 and human CD1d are implied.
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  • 74
    ISSN: 1432-1211
    Keywords: Key words RT1.S3 ; Grc ; MHC ; Class I ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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  • 75
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    International journal of biometeorology 41 (1998), S. 101-104 
    ISSN: 1432-1254
    Keywords: Key words Space flight ; Rat ; Plantaris muscle ; GLUT-4 ; Citrate synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract  The effects of 14 days of space flight on the glucose transporter protein (GLUT-4) were studied in the plantaris muscle of growing 9-week-old, male Sprague Dawley rats. The rats were randomly separated into five groups: pre-flight vivarium ground controls (PF-VC) sacrificed approximately 2 h after launch; flight groups sacrificed either approximately 5 h (F-R0) or 9 days (F-R9) after the return from space; and synchronous ground controls (SC-R0 and SC-R9) sacrificed at the same time as the respective flight groups. The flight groups F-R0 and F-R9 were exposed to micro-gravity for 14 days in the Spacelab module located in the cargo bay of the shuttle transport system – 58 of the manned Space Shuttle for the NASA mission named ”Spacelab Life Sciences 2”. Body weight and plantaris weight of SC-R0 and F-R0 were significantly higher than those of PF-VC. Neither body weight nor plantaris muscle weight in either group had changed 9 days after the return from space. As a result, body weight and plantaris muscle weight did not differ between the flight and synchronous control groups at any of the time points investigated. The GLUT-4 content (cpm/µg membrane protein) in the plantaris muscle did not show any significant change in response to 14 days of space flight or 9 days after return. Similarly, citrate synthase activity did not change during the course of the space flight or the recovery period. These results suggest that 14 days of space flight does not affect muscle mass or GLUT-4 content of the fast-twitch plantaris muscle in the rat.
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  • 76
    ISSN: 1432-072X
    Keywords: Key wordsV. cholerae O139 ; Lipopolysaccharide ; Electron microscopy ; Freeze-substitution technique ; Capsule
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The morphological and physical characteristics of the capsule of Vibrio cholerae O139 were examined. An electron microscopic study using the freeze-substitution technique showed that all of the V. cholerae strains of the O139 serogroup examined have a very thin fibrous layer on the outside of the outer membrane. In contrast, the mutants of strain O139, strain MO10T4 (which lacks capsule synthesis), and strain Bengal-2R1 (which fails to synthesize both the capsule and the O-antigen of lipopolysaccharide) were all found to have lost the surface layer. In addition, the capsule layer could also not be observed on the surface of V. cholerae strain O1. To determine the biological characteristics of the capsule of strains of the O139 serogroup, we investigated the serum killing activity and bacterial phagocytosis by polymorphonuclear leukocytes. The O139 strains were more resistant to the serum killing activity than were the V. cholerae O1 strain and the O139 mutant strains, thus suggesting that the existence of the capsule gave a serum-resistant character to the O139 strains. The surface character of the O139 strains had the same hydrophobic character as did that of the O139 mutant strains and the O1 strain. In addition, all the V. cholerae O1 and O139 strains examined, including the mutant strains, were effectively ingested by the human polymorphonuclear leukocytes. The number of ingested bacteria was not significantly different among the strains, and the ingestion of the acapsular O139 mutants thus showed that the capsule does not play an antiphagocytic role. These data suggest that the capsule of V. cholerae O139 has a physiological function different from that of the ordinal hydrophilic capsule that is found in invasive bacteria such as Klebsiella pneumoniae.
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  • 77
    ISSN: 1432-072X
    Keywords: Key words Magnetic bacteria ; Biomineralization ; Magnetite ; 16S rRNA ; In situ hybridization ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Natural enrichments of magnetic bacteria from the Itaipu lagoon near Rio de Janeiro were dominated by coccoid-to-ovoid morphotypes that produced unusually large magnetosomes. To determine the phylogenetic position of these unusual microorganisms, 16S rRNA genes were retrieved from bacteria magnetically separated from sediment of the Itaipu lagoon by in vitro amplification and cloning of PCR products into a plasmid vector. Partial sequencing of the obtained clones revealed two clusters of closely related sequences affiliated to a distinct lineage consisting exclusively of magnetic bacteria within the α-subclass of Proteobacteria. For a detailed phylogenetic analysis, several almost complete sequences of the 16S rRNA genes were determined. One representative clone of each cluster provided a PCR template for the in vitro transcription of group-specific polynucleotide probes complementary to a variable region of the 16S rRNA molecule. At least three different morphotypes of magnetic bacteria were reliably identified by post-embedding hybridization of ultra-thin sections. Electron microscopic analyses of hybridized cells enabled for the first time a detailed description of the morphological variety and ultrastructure of phylogenetically identified, uncultured magnetic bacteria. Two distinct coccoid bacteria were identified by the transcript probe complementary to the 16S rRNA sequence mabrj12, whereas the probe complementary to the sequence mabrj58 allowed the identification of an ovoid morphotype that displayed magnetosomes with the largest volumes observed to date.
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  • 78
    ISSN: 1432-9492
    Keywords: Transformation ; Clay-DNA complexes ; Nucleases ; X-ray diffraction ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract DNA bound on clay minerals, sand, and humic acids has been shown, both in vitro and in situ, to be capable of transforming bacteria and to resist degradation by nucleases, which could result in the crypticity of genes in soil and other natural habitats. To determine where DNA is bound on clay minerals, which may help to explain how bound DNA becomes resistant to degradation by nucleases but retains the ability to transform competent cells, chromosomal DNA from Bacillus subtilis bound on montmorillonite (M) and kaolinite (K) was examined by X-ray diffractometry and transmission and scanning electron microscopy. X-ray diffraction analysis showed that the basal spacings of M and K were not altered, indicating that this DNA did not significantly intercalate the clays. Scanning and transmission electron microscopy showed that the binding of this DNA was primarily on the edges of M and K, although some binding was also apparent on the planar surfaces. Based on the results of these studies, it is postulated that: 1.extension from the edges of the clays enables the unbound end of DNA to interact with receptor sites on competent cells and result in their transformation; and 2.binding on clays alters the electron distribution and/or conformation of DNA, which reduces its hydrolysis by nucleases.
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  • 79
    ISSN: 1432-0878
    Keywords: Key words N18-RE-105 cells ; Glutamate ; p53 ; Adriamycin ; Etoposide ; Differentiation ; SV40 large T antigen ; Mouse ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Process extension was induced in cells of the N18-RE-105 neuroblastoma-retinal hybrid line by toxic agents, including glutamate and the p53-inducing anticancer agents adriamycin and etoposide. Both adriamycin and glutamate activated p53 as measured by a plasmid transfection assay. It was therefore hypothesized that SV40 large T antigen, which binds p53, would interfere with cellular differentiation. To test this hypothesis, the temperature-sensitive form of SV40 large T was transduced into N18-RE-105 cells by retroviral infection. SV40 large T-infected cells became de-differentiated, grew in tightly-packed colonies, lost expression of neurofilament, and lost the ability to differentiate in response to glutamate and adriamycin. The de-differentiating effect of SV40 large T antigen may be due to binding and inactivation of cellular proteins, such as p53, p107, p130, p300, and retinoblastoma protein, which are important in cellular growth and differentiation. It is suggested that p53 may play a role in cellular differentiation, perhaps under unusual circumstances involving stress or cytotoxicity.
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  • 80
    ISSN: 1432-0878
    Keywords: Key words Elastin ; TGF-β1 ; Arteries ; In situ hybridization ; Immunohistochemistry ; Northern blot ; Ageing ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Several in vitro studies have previously demonstrated that the addition of TGF-β to aortic smooth muscle cells or skin fibroblasts stimulates elastin synthesis. It is not clear however whether, in vivo, TGF-β participates in the regulation of elastin synthesis, especially in physiological conditions. The aim of our study was to explore the localization of elastin mRNA and TGF-β1 in the rat thoracic aorta (an elastic artery) and caudal artery (a muscular artery). Elastin mRNA was localized by in situ hybridization and quantified using Northern blot analysis. TGF-β1 was detected using immunohistochemistry. The study was carried out as a function of age (rats of 3, 10, 20, and 30 months). We observed that TGF-β1 immunoreactivity is present predominantly, but not exclusively, at the sites of elastin synthesis as determined by elastin mRNA detection: in smooth muscle cells in the aorta and in endothelial cells in the caudal artery. The ability of exogenously added TGF-β1 (0.001–10 ng/ml) to modulate the steady-state levels of elastin mRNA in primary cultures of endothelial cells, smooth muscle cells, and fibroblasts isolated from the thoracic aorta was also studied. At the highest concentration used, elastin mRNA levels increased 5-fold in endothelial cells and 11-fold in smooth muscle cells. The demonstration that TGF-β1 immunoreactivity is present at the sites of elastin synthesis in the thoracic aorta and in the caudal artery and the observation that TGF-β1 induces an increase in elastin mRNA levels in cultured endothelial cells and smooth muscle cells suggest that TGF-β1 may be implicated, at least in part, in the physiological regulation of elastin gene expression.
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  • 81
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    Cell & tissue research 291 (1998), S. 445-454 
    ISSN: 1432-0878
    Keywords: Key words Serum-free medium ; Survival ; Chondroitin sulfate ; Culture substratum ; Brain neuron ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  When cells dissociated from the neonatal rat brains are plated on a poly-lysine-coated surface in a serum-free medium, they display a strange morphology: a dark and extended cell body. Preincubation of the surface with fetal bovine serum was found to inhibit the appearance of this strange contraction of the basal cell sheets in a dose-dependent manner. This finding indicated the presence of a factor(s) in the serum, which might be an appropriate substratum for prolonged survival of brain neurons. In the current study, this factor was highly purified through DEAE ion-exchange chromatography followed by gel filtration. The factor was eluted from a Superose column at fractions corresponding to a molecular weight greater than 1000 kDa. By SDS-PAGE analysis, these fractions were found to contain a major band (≥1000 kDa) positive for alcian blue and few minor bands faintly stainable with Coomassie blue. The activity of the purified sample, inducing the morphological change in cells, was diminished by incubation with chondroitinase ABC. Neither heparitinase II, hyaluronidase, nor trypsin modified the activity. An authentic chondroitin sulfate (type B) mimicked the serum action on the morphology of brain cells in early stages of culture. Taking these findings together, it is suggested that the factor in serum beneficial for the attachment of brain cells is composed of a chondroitin sulfate with a Mr greater than 1000 kDa. Cortical cells dissociated from the neonatal rat brain attached well to the purified factor-coated surface and displayed a healthy morphology: an optically-reflective cell body with thick neurites for at least 3 days in the absence of serum.
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  • 82
    ISSN: 1432-0878
    Keywords: Key words Retina ; Rod bipolar cells ; Amacrine cells ; Protein kinase C ; Glutamic acid decarboxylase ; GABA ; Synaptic circuitry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The synaptic connectivity between rod bipolar cells and GABAergic neurons in the inner plexiform layer (IPL) of the rat retina was studied using two immunocytochemical markers. Rod bipolar cells were stained with an antibody specific for protein kinase C (PKC, α isoenzyme), and GABAergic neurons were stained with an antiserum specific for glutamic-acid decarboxylase (GAD). Some amacrine cells were also labeled with the anti-PKC antiserum. All PKC-labeled amacrine cells examined showed GABA immunoreactivity, indicating that PKC-labeled amacrine cells constitute a subpopulation of GABAergic amacrine cells in the rat retina. A total of 150 ribbon synapses established by rod bipolar cells were observed in the IPL. One member of the postsynaptic dyads was always an unlabeled AII amacrine cell process, and the other belonged to an amacrine-cell process showing GAD immunoreactivity. The majority (n=92) (61.3%) of these processes made reciprocal synapses back to the axon terminals of rod bipolar cells. In addition, 78 conventional synapses onto rod bipolar axons were observed, and among them 52 (66.7%) were GAD-immunoreactive. Thus GABA provides the major inhibitory input to rod bipolar cells.
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  • 83
    ISSN: 1432-0878
    Keywords: Key words PC12 ; hNT2 ; Neuroblastoma cell lines ; NGF ; Retinoic acid ; Rat ; Human cell lines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Neuroendocrine-specific protein (NSP) reticulons are expressed in neural and neuroendocrine tissues and cell cultures derived therefrom, while most other cell types lack NSP-reticulons. Three major subtypes have been identified so far, designated NSP-A, NSP-B, and NSP-C. We have investigated the correlation between the degree of neuronal differentiation, determined by morphological and biochemical criteria, and NSP-reticulon subtype expression. For this purpose, several human neuroblastoma cell lines, exhibiting different degrees of neuronal differentiation, were examined immuno(cyto) chemically. It became obvious that the expression of NSP-C, as detected by immunofluorescence microscopy and Western blotting, is most prominent in cell lines with a high degree of neuronal differentiation, such as LA-N-5. Such highly differentiated cells also express other neural and neuroendocrine markers, such as neural cell adhesion molecule (NCAM), neurofilament proteins, synaptophysin, and chromogranin. NSP-A was observed in all cell lines to a different extent. However, no clear correlation was observed with the degree of neuronal differentiation as defined by other neuronal and neuroendocrine markers or morphology. NSP-B could not be detected. The induction of neuronal differentiation with nerve growth factor, dbcAMP, and retinoic acid in the rat pheochromocytoma cell line PC12 and the human teratocarcinoma cell line hNT2, respectively, induced the expression of NSP-A and NSP-C in these cell lines parallel to the induction of neurofilament protein expression. It is concluded that NSP-C expression, in particular, is strongly correlated with neuronal differentiation.
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  • 84
    ISSN: 1432-0878
    Keywords: Key words Osteoclasts ; Osteoblasts ; Osteocytes ; Bone ; Substance P (SP) ; Neurokinin-1 receptor (NK1-R) ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Substance P (SP) is a neuropeptide that is released from axons of sensory neurons and causes signal transduction through the activation of the neurokinin-1 receptor (NK1-R). The present study demonstrates the distribution of SP-like-immunoreactive (SP-LI) axons and the localization of NK1-Rs in rat bone tissue using the avidin-biotin-peroxidase complex method. Axons with SP-LI were commonly found near the trabecular bone in the temporal bone marrow, but they were only sparsely distributed in the mandible, femur, and tibia. Immunoreactivity for NK1-Rs was found on the plasma membrane and in the cytoplasm of the osteoclasts. In the osteoblasts and osteocytes, a small number of weak, punctate immunoreactive products of NK1-Rs were distributed close to the plasma membrane. At the electron-microscopic level, immunoreactivity for NK1-R was distributed mainly in the whole cytoplasm, except for the clear zone of the osteoclasts, and in pit-like structures along the plasma membrane. The NK1-R-immunoreactive structures in the cytoplasm were divided into two types of organelles, consisting of vesicular and vacuolar structures (probably transport vesicles and early endosomes). In the osteoblasts and osteocytes, the number of NK1-R-positive vesicular structures was fewer than in the osteoclasts. These results thus suggest that SP secreted by the sensory axons could directly modulate bone metabolism via NK1-Rs.
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  • 85
    ISSN: 1432-0878
    Keywords: Key words Vinculin ; Talin ; Integrin ; Dystrophin ; Spectrin ; T-tubule ; Costamere ; Basal membrane ; Cardiac muscle cell ; Dilated cardiomyopathy ; Human ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The transverse tubule system of the cardiomyocyte remains undeformed despite the extreme forces it undergoes during the contraction-relaxation cycle, but the morphological basis for its stability remains unclear. Therefore, we have investigated the architecture and subcellular protein scaffold of the cardiac T-tubules and compared it with that of the costameres and of the free sarcolemma. Tissue samples from normal rat and monkey hearts, and left ventricular tissue from normal and cardiomyopathic human hearts obtained at transplantation surgery were investigated using immunocytochemistry and confocal microscopy and by electron microscopy. In addition, we used a re-differentiation model of isolated, cultured adult rat cardiomyocytes. The cell membrane of the cardiac T-tubules was found to contain the cell-matrix focal adhesion molecules (FAMs) vinculin, talin, the α5β1 integrin and the membrane-associated proteins (MAPs) dystrophin and spectrin. FAMs and MAPs were localized in the T-tubular membrane in a similar pattern: in longitudinally oriented myocytes as transverse punctate lines at the Z-level; in transversally cut myocytes a radial tubular network was found to extend throughout the interior of the cell. Immunolabeling for basement membrane components including collagen IV, fibronectin and laminin showed a colocalization with FAMs and MAPs parallel to the transverse T-tubules. The costameres of the sarcolemma showed a protein composition resembling that of the T-tubules but the intervening segments of free sarcolemma showed absence of FAMs and presence of MAPs. For the first time, we demonstrate the existence and protein composition of the T-tubular scaffold in the human heart. Furthermore, we show that cardiomyocytes from human failing hearts have less abundant but more dilated T-tubules than do experimental animals. These results indicate that the cardiac T-tubular system contains a subcellular scaffold closely resembling that of the costameres. It consists of FAMs, MAPs and basal lamina proteins that confer structural integrity to the cardiac T-tubular membrane during contraction/relaxation cycles.
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  • 86
    ISSN: 1432-0878
    Keywords: Key words Prion protein (PrPc) ; Electron microscopy ; Secretory granules ; Membrane ; Extracerebral tissues ; Hamster ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  In transmissible spongiform encephalopathies (TSE), such as scrapie in animals and Creutzfeldt-Jakob disease in humans, the central event is the conversion of a host-encoded amyloidogenic protein (PrPc) into an abnormal isoform (PrPsc) that accumulates as amyloid in TSE brain. PrPc is a membrane sialoglycoprotein synthesized in the central nervous system and elsewhere. We have examined the ultrastructural localization of PrPc in numerous hamster and some human extracerebral tissues, by means of a post-embedding electron-microscopic method combined with immunogold labeling. In stomach, intestine, lung, and kidney from hamsters, and in stomach, kidney, and spleen from humans, immunogold labeling specific for PrPc is observed on various cellular substructures related to secretory pathways: Golgi apparatus, secretory globules, and plasma membrane. In mucous epithelial cells of stomach and intestine, PrPc appears to be concentrated in secretory globules, suggesting a role for PrPc in the secretory function of the digestive tract. The secretory aspect of PrPc may be a key to understanding the physiopathological mechanisms underlying TSE.
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  • 87
    ISSN: 1432-0878
    Keywords: Key words Pancreas ; Stomach ; Duodenum ; Ribonuclease protection assay ; Immunocytochemistry ; Protease ; Rat ; (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Prior studies have revealed the presence of chymotrypsinlike protease in peripheral organs, although no definitive evidence for the synthesis of this enzyme in tissue other than the pancreas is available. In an attempt to detect chymotrypsinogen mRNA in peripheral organs, a fragment of the pancreatic chymotrypsin mRNA from rat was amplified using PCR. The sequence was identified as a portion of the rat chymotrypsin B gene overlapping exon 5 through exon 7. It was subcloned into the pGEM-4Z vector and used as a template for the vitro transcription of an antisense riboprobe. Using ribonuclease protection and Northern blot analyses, chymotrypsin mRNA was detected in the rat pancreas, stomach, duodenum, ovary, and spleen. Monoclonal and polyclonal antisera against chymotrypsin detected chymotrypsinlike immunoreactivity in rat and human pancreas, rat stomach, duodenum and jejunum. Electrophoresis and immunoblotting revealed chymotrypsin-chymotrypsinogen bands (25–29 kDa) in the stomach and duodenum. Synthesis of a potent protease such as chymotrypsin in tissue other than pancreas is significant, suggesting a potential physiological and/or pathological role in these tissues.
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  • 88
    ISSN: 1432-0878
    Keywords: Key words Connexin ; Gap junctions ; Smooth muscle ; Intestinal pacemaker ; Confocal laser scanning microscope ; Dog ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Cellular networks of pacemaker activity in intestinal movements are still a matter of debate. Because gap-junctional intercellular communication in the intestinal wall may provide important clues for understanding regulatory mechanisms of intestinal movements, we have attempted to clarify the distribution patterns of three types of gap junction proteins. Using antibodies for connexin40, connexin43, connexin45, smooth muscle actin, and vimentin, immunocytochemical observations were made with the confocal laser scanning microscope on cryosections of fresh-frozen small intestine and colon of the dog and rat. Connexin 45 was localized along the deep muscular plexus of the small intestine in both dog and rat. Double labeling studies revealed that connexin45 overlapped with vimentin –, but not actin-positive areas, indicating the fibroblast-like nature of the cells, rather than their being smooth muscle-like. Connexin43 immunoreactivity appeared along the smooth muscle cell surface in the outer circular layer of the small intestine of both animals. Connexin 40 immunoreactivity was not observed in the muscle layer other than in the wall of large blood vessels. It is suggested that connexin45-expressing cells along the deep muscular plexus of dog and rat small intestine are likely to act as a constituent of a pacemaker system, which may include a conductive system, by forming a cellular network operating via specific types of gap junctions.
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  • 89
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    Cell & tissue research 292 (1998), S. 613-617 
    ISSN: 1432-0878
    Keywords: Key words Sensory nerve endings ; Calretinin ; Laryngeal mucosa ; Immunohistochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution of laminar nerve endings that contained immunoreactive calretinin was examined in the laryngeal mucosa of the adult rat. In whole-mount preparations, the immunoreactive laminar endings were distributed in the supraglottic region but not in the subglottic region. The laminar endings that arose from thick nerve fibers with or without swellings were identified as corpuscles with many variform terminal arborizations. They appeared to be located at the interface between the epithelium and the subepithelial connective tissue. The terminals were scattered under the basal lamina of the epithelium, and some of them were located within the epithelial layer. Immunoelectron microscopy revealed that both sub- and intraepithelial immunoreactive terminals that were filled with mitochondria were partly or totally ensheathed by Schwann cell processes. The denervation experiments, in which the superior laryngeal nerve was cut unilaterally or bilaterally, suggested that the laminar endings originate from the superior laryngeal nerve with strict ipsilateral innervation. The laminar endings might be associated with detection of changes in pressure in the laryngeal cavity or chemical stimuli.
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  • 90
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    Cell & tissue research 293 (1998), S. 1-22 
    ISSN: 1432-0878
    Keywords: Key words Piecemeal degranulation ; Histamine ; Charcot-Leyden crystal protein ; Anaphylactic degranulation ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The evidence for vesicular transport as a mechanism for secretion by human basophils is reviewed. Initially, direct electron-microscopic inspection of experimentally produced and sequentially biopsied contact allergy skin lesions revealed a unique form of secretion termed piecemeal degranulation, characterized by the slow emptying of secretory granule contents (with retention of empty containers) in the absence of extrusion of entire granules. Budding of small vesicles to/from secretory granules was observed, and cytoplasmic vesicles were abundant. A generalized degranulation model was proposed to unify classical regulated secretion and this new form of secretion. Investigation of the mechanism(s) of secretion from human basophils required the development of numerous tools and resources. Chief among these were: (a) isolation and purification of circulating basophils; (b) identification of specific growth factors to increase the supply of this rare granulocyte; (c) understanding of secretogogue mechanisms and reliable analyses of secreted basophil products; and (d) development of ultrastructural preparations allowing imaging of small vesicles and quantifiable small electron-dense tags for granule materials in small vesicles. Applications of these tools to well-defined models of basophil secretion have established a role for vesicles as a mechanism for effecting secretion of histamine and the Charcot-Leyden crystal protein from activated human basophils.
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  • 91
    ISSN: 1432-0878
    Keywords: Key words Adhering junctions ; Desmosomes ; Endothelial junctions ; Plaque proteins ; Desmoplakin ; Cadherins ; Protein ZO-1 ; Rat ; cell culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Two major types of plaque-bearing adhering junctions are commonly distinguished: the actin microfilament-anchoring adhaerens junctions (AJs) and the desmosomes anchoring intermediate-sized filaments (IFs). Both types of junction usually possess the common plaque protein, plakoglobin, whereas the other plaque proteins and the transmembrane cadherins are mutually exclusive. For example, AJs contain E-, N-, or P-cadherin in combination with α- and β-catenin, vinculin and α-actinin, whereas in desmosomes, desmogleins and desmocollins are associated with desmoplakin and one or several of the plakophilins (PP1–3). Here we describe a novel type of adhering junction comprising proteins of both AJs and desmosomes and the tight junction (TJ) plaque protein, ZO-1, in a newly established, liver-derived tumorigenic rat cell line (RMEC-1). By immunofluorescence microscopy, cell-cell contacts are characterized by mostly continuous-appearing lines which are usually resolved by electron microscopy as extended arrays of closely spaced small plaque subunits. These plaque-covered regions are positive for plakoglobin, α- and β-catenin, the arm-repeat protein p120, vinculin, desmoplakin and protein ZO-1. They are positive for E-cadherin in cultures early on in passaging, but tend to turn negative for all known cadherins in densely grown cultures. On immunoblotting SDS-PAGE-separated proteins from dense-grown cell monolayers, “pan-cadherin” antibodies have reacted with a band at ∼140 kDa, identified as N-cadherin by peptide fingerprinting of the immunoprecipitated protein, which for reasons not yet clear is modified or masked in immunolocalization experiments. The exact histological derivation of RMEC-1 cells is not known. However, the observations of several endothelial markers and the fact that all cells are rich in IFs containing vimentin and/or desmin, while only subpopulations also reveal IFs containing CKs 8 and 18, is suggestive of a mesenchymal, probably endothelial origin. We discuss the molecular relationship of this novel type of extended junction with other types of adhering junctions.
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  • 92
    ISSN: 1432-0878
    Keywords: Key words Nerve growth factor ; Hypertension ; Contact inhibition ; Proliferation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Elevated target-derived smooth muscle nerve growth factor (NGF) and resultant neurogenic plasticity are associated with both hypertension and hyperactive voiding in spontaneously hypertensive rats (SHRs: hypertensive, behaviorally hyperactive). In culture, vascular (VSMCs) and bladder (BSMCs) smooth muscle cells derived from SHRs secrete higher levels of NGF, proliferate more rapidly, and achieve higher density at confluence than do control Wistar-Kyoto (WKY) cells. To elucidate growth-related contributions to the elevated tissue NGF observed in SHRs, we examined vascular VSMC and BSMC NGF secretion in two inbred cell lines (WKHTs, hypertensive; WKHAs, hyperactive) derived from SHRs and WKYs to assess the phenotypic association of altered NGF metabolism with either hypertension or behavioral hyperactivity. Cell density, rather than growth rates, was the most important factor with respect to NGF secretion. VSMC density varied such that WKHT=SHR〉WKY= WKHA, higher VSMC density being associated with higher NGF output. However, in BSMC cultures, NGF output was the lowest in high density cell lines, with WKHT〉SHR〉WKY〉WKHA. SHR BSMCs had the second highest cell density and NGF secretion level. Elevated packing density, presumably because of a lack of contact inhibition, co-segregated with the hypertensive phenotype in both VSMCs and BSMCs. Thus, dysfunctional smooth muscle growth characteristics may contribute to the augmented vascular and bladder NGF content associated with high blood pressure and hyperactive voiding in SHRs.
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  • 93
    ISSN: 1432-0878
    Keywords: Key words Endothelial cells ; Alkaline phophatase ; Primary cultures ; Proliferation ; Gene expression ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Primary cultures of rat myocardial capillary endothelial cells were established and characterized. A range of typical endothelial cell-specific markers were retained in vitro. Cell kinetic studies in confluent endothelial-cell cultures in vitro revealed a roughly 50-fold increase in the proportion of cells in s-phase, indicating a very considerable shortening of cell turnover time, compared to in vivo conditions. Alkaline phosphatase enzyme activity and encoding mRNA are strongly expressed in myocardial capillary endothelial cells in vivo, but were not detectable in vitro. This was true in cell cultures from two strains of rat, which revealed significantly different enzyme expression levels in vivo. In co-cultures of pericytes and endothelial cells, positive ALP enzyme reaction was detected in pericytes, which in vivo show only very weak enzyme reactivity. Treatment of cell cultures with ≤10 M retinoic acid had no effect in pure endothelial cell cultures, but did increase ALP expression of pericytes in co-cultures. The observation of a loss of endothelial ALP expression in vitro supports other in vitro as well as our own in vivo observations, indicating a negative correlation of ALP expression and proliferative activity of endothelial cells.
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  • 94
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    Cell & tissue research 291 (1998), S. 575-579 
    ISSN: 1432-0878
    Keywords: Key words Chromatoid body ; Polysomes ; RNA ; Spermatid ; Spermatogenesis ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  A procedure for isolating the chromatoid body from the testis of 40-day-old rats was developed. Electron-microscopical analysis indicated that about 70% of the isolated organelles were chromatoid bodies, while the remaining structures corresponded to dense bodies and probably to satellites. Negative staining of the isolated organelles revealed the presence of polysome-like structures in about 20% of the chromatoid bodies suggesting that the polysomes were not due to contamination with cytoplasmic polysomes. Moreover, the presence of RNA in the stroma of the chromatoid body was confirmed by RNAse-gold staining. Preliminary electrophoretic analysis of the RNA extracted from the organelles revealed the presence of a complex population of RNAs including 5.8 and 5 S ribosomal RNAs but no tRNA.
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  • 95
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    Cell & tissue research 292 (1998), S. 367-375 
    ISSN: 1432-0878
    Keywords: Key words Larynx ; Edema ; Mast cells ; Compound 48/80 ; Substance P ; Capsaicin ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  In the rat larynx, plasma exudation and edema formation were studied by light and electron microscopy after i.v. injections of the mast cell activator compound 48/80, substance P, and capsaicin. The morphological effects of substance P and capsaicin on connective tissue mast cells in vivo were also examined. Of the drugs tested, only compound 48/80 degranulated the connective tissue mast cells. All drugs induced a subepithelial plasma exudation in the subglottic region, with edema in the lamina propria and widened intraepithelial intercellular spaces, though the tight junction regions seemed intact. In the epiglottis, 10 min after compound 48/80 injection, there was edema in the lamina propria on the lingual side, with an intact and tight epithelial lining. No morphological sign of edema was found in the epiglottis after injection of substance P or capsaicin. The pronounced effect found in the epiglottic region after compound 48/80 injection was due to the release of mediators such as histamine and 5-hydroxytryptamine from the connective tissue mast cells. This study supports the belief that substance P in vivo mediates an increased vascular permeability by a direct effect on the blood vessels – a mechanism distinct from mast cell degranulation.
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  • 96
    ISSN: 1432-0878
    Keywords: Key words Angiogenesis ; Capillary growth ; Prazosin ; Shear stress ; Skeletal muscle ; Ultrastructure ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Chronic vasodilatation represents a stimulus for capillary growth associated with increased luminal shear stress. We have examined the ultrastructure of more than 2000 capillaries to establish whether the sequence of angiogenesis in response to this stimulus is similar to that described during development and under pathological circumstances. Administration of the α1-blocker prazosin to rats for 2 weeks led to a greater capillary length density in extensor hallucis proprius muscles without any change in capillary tortuosity: J v(c,f)=262±54 compared with 350±17 mm–2, control compared with prazosin (P〈0.002). There were obvious signs of endothelial cell (EC) activation after prazosin treatment, including an increased proportion of capillaries with rough endoplasmic reticulum, large cytoplasmic vacuoles, thickened endothelium and an irregular luminal surface. Capillaries from control muscles had a maximum of three ECs in cross section, whereas four ECs were noted in 0.8+0.5% of capillaries after 1 week (n.s.) and 2.5±0.9% after 2 weeks (P〈0.01) of treatment. This could be due to elongation and/or migration of ECs, as cell proliferation has not been described at these time points. There was also an increase in the proportion of capillaries having a narrow, slit-like lumen (1.7±0.8% of controls; 7.1±1.9% at 1 week; 8.8±2.5% at 2 weeks; P〈0.02), some of which were smaller in size (less than 2 μm diameter) than in controls (3–5 μm) and/or “seamless”, i.e. lacking EC junctions. These may represent newly formed vessels. Focal discontinuity of the basement membrane and abluminal EC processes were rarely seen, and capillary growth by abluminal sprouting appeared to be very infrequent (less than 0.001% of profiles). Of more importance was growth starting from the luminal side. Significantly more thin cytoplasmic processes were observed protruding into the lumen of capillaries after 1 week (47.5±6.2%, P〈0.001) and 2 weeks of prazosin (34.2±5.5%, P〈0.05) than in control vessels (16.7±3.9%). Some of these traversed the entire lumen and connected with endothelium of the opposite side, probably involving membrane fusion, resulting in the appearance of a double lumen. Individual capillaries with a complete double lumen were observed after 2 weeks’ prazosin but comparatively rarely, in only four out of six muscles. These findings indicate a pattern of luminal growth which is completely different from intussusceptive growth previously described during development, and from the abluminal capillary sprouting seen under pathological circumstances.
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  • 97
    ISSN: 1432-0878
    Keywords: Key words Dendritic cells ; Maturation ; Intrahepatic translocation ; Immunohistochemistry ; Electron microscopy ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Specific populations of hepatic sinusoidal cells were stained with monoclonal antibodies that recognize monocytes/macrophages (ED1), tissue macrophages (Kupffer cells) (ED2), MHC class II (Ia) antigen (MRC OX6), and dendritic cells/γ,δ T-cells (MRC OX62) and analyzed by light and electron microscopy. The majority of ED1+ and/or ED2+ cells were localized to the hepatic parenchyma, whereas OX6+ and/or OX62+ cells were more densely distributed within Glisson’s sheath than in the hepatic parenchyma. Double-immunoperoxidase staining of normal liver for ED1, ED2, and OX6 identified dendritic cells (DC) of two different phenotypes, ED1+ED2–OX6+ and ED1–ED2–OX6+. DC can be classified into three different types based on ultrastructural characteristics. The first type (type I) is characterized by one or more long cytoplasmic processes and a well-developed lysosomal system. The second type (type II) has an inconspicuous lysosomal system, abundant hyaloplasm, and characteristic short cytoplasmic processes. The third type (type I–II) has cytologic features intermediate between those of type I and type II DC. At the electron-microscopic level, these three cell types are found in the sinusoidal lumen, whereas the majority of type II DC are located in the space of Disse and Glisson’s sheath. Furthermore, some OX6-labeled elongated DC appeared to traverse the lumen of sinusoids through endothelial pores to enter the space of Disse. One hour after intravenous injection of latex particles (0.81 μm in diameter), numerous latex-laden dendritic cells (ED1+OX6+, type I and type I–II) were detected in the lumen of hepatic sinusoids, but not in the space of Disse or Glisson’s sheath. These findings suggest that normal rat liver contains resident dendritic cells which downregulate phagocytic activity and mature into potent accessory cells during migration from the portal vein toward the central vein. These DC then traverse the sinusoidal lumen to the hepatic lymph system via the space of Disse.
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  • 98
    ISSN: 1617-4623
    Keywords: Key words Bacteriophage λ ; DnaA-DNA interactions ; Electron microscopy ; DNA-protein complexes ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Interaction of the Escherichia coli DnaA (replication initiator) protein with restriction fragments of phage λ DNA demonstrated differential binding of DnaA along the whole λ DNA. Interaction of DnaA with the λ replication region (from the promoter p R to the origin of replication, oriλ) demonstrated a strong binding of DnaA to the region around the p o promoter where synthesis of a short antisense oop RNA is initiated. The four sequences protected by DnaA (two 9mers and two 5mers) are not related even to a relaxed DnaA box. The pattern of protection of these four sequences and the location of three DNase I hypersensitive sites in the λ DNA r strand, together with results of mobility shift assays and electron microscopy studies, may indicate an interaction involving DnaA monomers bound to different DNA positions on one side of the helix and the formation of higher-order nucleoprotein structures. Therefore, it is tempting to suggest that DnaA, in addition to its activity in regulation of replication and transcription, could be considered as a factor which structures certain chromosomal regions.
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  • 99
    ISSN: 1615-6102
    Keywords: Sporopollenin ; Solubilisation ; 2-Aminoethanol ; Reaggregation ; Electron microscopy ; X-ray microscopy ; Thypha angustifolia L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Exines fromTypha angustifolia L. pollen were dissolved in hot 2-aminoethanol. The solubilisate was successively fractionated and reaggregated via a dialysis cascade with dialysis tubings of different exclusion volumina. Four fractions of reaggregated material with different molecular mass were obtained. Fraction 1 with a molecular mass above 25,000 Da, fraction 2 with a molecular mass between 10,000–25,000 Da, fraction 3 with a molecular mass between 5,000–10,000 Da, and fraction 4 of a molecular mass lower than 5,000 Da. The fractions were comparatively analysed by scanning and transmission electron microscopy and X-ray microscopy. The material of the fractions with a molecular mass above 10,000 Da exhibit high congruence to the initial material. Analysis of the reaggregated material with the lowest molecular mass revealed special distinct substructures which in form and size showed high similarities to substructures of exines described in literature. In detail, spherical substructures consisting of an electron-dense core surrounded by an electron-transparent corona and in addition elongated substructures with a distinctive surface sculpture were detected.
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  • 100
    ISSN: 1615-6102
    Keywords: Callose ; Electron microscopy ; Gasteria verrucosa ; Phenolics ; Phytomelan ; Seed coat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the seed coat ofGasteria verrucosa the deposition of phytomelan takes place during seed development in three stages. Phytomelan is a black cell wall material which is chemically very inert. First the radial walls and part of the transverse cell wall of the outer epidermis of the outer integument become thickened by exocytosis of dictyosome vesicles. Callose is deposited at the tangential plasma membrane against those walls. After the callose deposition about two thirds of the original cell volume is filled with callose. During the second stage the callose is broken down, probably into glucose monomers or small polymers. At the same time cellulose is deposited at the outer tangential plasma membrane, forming a wall between the dissolving callose and the plasma membrane. In the third phase small granules appear in the solution of dissolved callose. which grow out and finally fuse to form a block of phytomelan, consisting of spherical 15-nm units. Remarkable is the function of the callose: it determines the size of the phytomelan block, and it probably functions as carbohydrate source for the phytomelan synthesis and/or for the cellulose inner layer. In this study transmission electron microscopy and cryo scanning electron microscopy are used to study the three developmental stages of the formation of the phytomelan layer.
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