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  • tropical pond  (2)
  • *Tumor Suppressor Proteins  (1)
  • Acartia clausi  (1)
  • 1995-1999  (1)
  • 1990-1994  (3)
  • 1955-1959
  • 1
    Electronic Resource
    Electronic Resource
    Role of bacteria as food for zooplankton in a eutrophic tropical pond (Ivory Coast) (1994)
    Springer
    Aquatic ecology 28 (1994), S. 167-174 
    Details
    ISSN: 1573-5125
    Keywords: bacteria ; zooplankton ; grazing ; tropical pond ; eutrophic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The aim of the study was to determine whether bacteria could be a substantial source of carbon for zooplankton and whether the grazing pressure of these metazoan filter-feeders could influence the fate of bacterial production. Eight grazing experiments using natural bacteria labelled with3H thymidine were conducted in a tropical pond (Ivory Coast) during various phases of biological colonization (rotifer-dominated and copepod-dominated phases of the colonization). Higher grazing and clearance rates were observed with rotifers (Brachionus plicatilis andHexarthra intermedia), while very low values were obtained when the cyclopoid copepodApocyclops panamensis was dominant. Less than 1% of the bacterial production was harvested when copepods were dominant, whileB. plicatilis consumed up to 36% of this production. However, this consumption of bacteria appeared to contribute only to an insignificant proportion of the daily carbon intake (e.g. 0.9 to 7.1% of body carbon for rotifers). The low contribution of bacteria in the nutrition of zooplankton is discussed in terms of their cell size and their relative abundance in the total amount of seston available.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02333987
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    In situ metabolic budget for the calanoid copepod Acartia clausi in a tropical brackish water lagoon (Ebrié Lagoon, Ivory Coast) (1994)
    Springer
    Hydrobiologia 272 (1994), S. 147-161 
    Details
    ISSN: 1573-5117
    Keywords: Acartia clausi ; copepod ; tropical lagoon ; metabolic budgets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Simultaneous measurements of respiration, excretion and production rates were carried out several times over a year period at five representative stations of the Ebrié Lagoon. Assuming a constant assimilation efficiency rate of 69.4%, we derived metabolic budgets for carbon, nitrogen and phosphorus. Daily specific ingestion rates calculated were rather generally high, and ranged between 54 and 159% of body carbon, between 26 and 102% of body nitrogen and between 108 and 307% of body phosphorus. Regional and seasonal variations depended mainly upon variations in trophic conditions. Curvilinear relationships between ingestion production, or net production efficiency K2, and food concentration (as chlorophyll-a + phaeopigments) showed that food could have been a limiting factor. Furthermore, K2 were low when compared with data from the literature (mean of 21% in carbon, 39% in nitrogen and 11% in phosphorus). Complementary laboratory experiments carried out on adults fed with enriched natural particles or algal cultures (Tetraselmis sp. or Dunaliella sp.) showed similar production (egg-production) vs food concentration curvilinear relationships as in the field. However, considerably higher maximal ingestion and production rates were obtained for animals fed algal cultures suggesting that optima for food acquisition and transformation were not reached in field conditions. Consequently, A. clausi, which represents more than 50% of the zooplankton biomass, appears to be rather inefficient in transforming the abundant particulate organic matter produced in the lagoon. This results from its high level of metabolic expenditure through respiration or excretion (about 50% of ingestion in terms of carbon) and from the small size and poor trophic value of food particles (high percentage of detritus).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00006518
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  • 3
    Electronic Resource
    Electronic Resource
    Ecological organization and succession during natural recolonization of a tropical pond (1994)
    Springer
    Hydrobiologia 294 (1994), S. 229-242 
    Details
    ISSN: 1573-5117
    Keywords: bacteria ; phytoplankton ; protozoa ; rotifera ; cyclopoids ; succession ; recolonization ; tropical pond
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The structure of a planktonic community was studied in April 1990 for 24 days (D1 to D24) during the natural recolonization of a tropical pond (Côte d'Ivoire) made azoic by emptying and liming (D0). Abundances of bacterioplankton, phytoplankton, protozoans and zooplankton were studied twice daily, whereas hydrological descriptors (temperature, conductivity, oxygen, pH, dissolved nutrients, sestonic weights) were recorded several times daily. After the pond treatment, the natural refilling from groundwater began immediately. The microheterotrophic (bacteria, flagellates, ciliates), phytoplanktonic (Coelastrum microsporum) and zooplanktonic (the rotifers Brachionus plicatilis and Hexarthra intermedia) communities were first based on opportunist species favored by the initially large nutritive availability. This close link with the trophic resources induced their rapid elimination, as soon as the food source was depleted by overconsumption. Due to liming effects, great amounts of degradable organic compounds allowed bacterial communities to develop before phytoplankton. This biological succession was first based on a catastrophic-type system, successively controlled by bottom-up factors (proliferation) and top-down factors (species collapse). Then, the colonization was completed with the development of secondary consumers (last stages of Apocyclops panamensis and chironomids). The progressive complexity of the system ensured the attenuation of the disturbing events. Finally, due to volume variations of the pond along the recolonization steps, the effects of the dilution process on bacteria and chlorophyll biomass were studied. In a context of non-limiting nutrient substrata, the microbial community was able to colonize the new volume within a few hours. Phytoplankton showed a more complex adaptation to the volume increase, with mixed effects of grazing, sedimentation and diurnal productions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021296
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  • 4
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    Role of the ubiquitin-proteasome pathway in regulating abundance of the cyclin-dependent kinase inhibitor p27 (1995)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1995-08-04
    Description: The p27 mammalian cell cycle protein is an inhibitor of cyclin-dependent kinases. Both in vivo and in vitro, p27 was found to be degraded by the ubiquitin-proteasome pathway. The human ubiquitin-conjugating enzymes Ubc2 and Ubc3 were specifically involved in the ubiquitination of p27. Compared with proliferating cells, quiescent cells exhibited a smaller amount of p27 ubiquitinating activity, which accounted for the marked increase of p27 half-life measured in these cells. Thus, the abundance of p27 in cells is regulated by degradation. The specific proteolysis of p27 may represent a mechanism for regulating the activity of cyclin-dependent kinases.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Pagano, M -- Tam, S W -- Theodoras, A M -- Beer-Romero, P -- Del Sal, G -- Chau, V -- Yew, P R -- Draetta, G F -- Rolfe, M -- New York, N.Y. -- Science. 1995 Aug 4;269(5224):682-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Mitotix Inc., Cambridge, MA 02139, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7624798" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/metabolism ; Anaphase-Promoting Complex-Cyclosome ; Animals ; *Cell Cycle Proteins ; Cell Line ; Cyclin-Dependent Kinase Inhibitor p27 ; Cyclin-Dependent Kinases/*antagonists & inhibitors ; Cysteine Endopeptidases/*metabolism ; Electroporation ; Enzyme Inhibitors/metabolism ; Humans ; Kinetics ; Leupeptins/pharmacology ; Ligases/metabolism ; Mice ; Microtubule-Associated Proteins/*metabolism ; Multienzyme Complexes/*metabolism ; Proteasome Endopeptidase Complex ; Rabbits ; Recombinant Proteins/metabolism ; Succinates/pharmacology ; Tumor Cells, Cultured ; *Tumor Suppressor Proteins ; Ubiquitin-Conjugating Enzymes ; *Ubiquitin-Protein Ligase Complexes ; Ubiquitin-Protein Ligases ; Ubiquitins/*metabolism
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
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