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  • AERODYNAMICS  (2,823)
  • Animals
  • Fisheries
  • SPACE SCIENCES
  • 1990-1994  (5,097)
  • 1
    Electronic Resource
    Electronic Resource
    Exploring the effects of multiple management objectives and exotic species on great lakes food webs and contaminant dynamics (1992)
    Springer
    Environmental management 16 (1992), S. 225-229 
    Details
    ISSN: 1432-1009
    Keywords: Fisheries ; Phosphorus ; Contaminants ; Ecosystem ; Management ; Simulation model ; Great Lakes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A simulation model was developed to describe linkages among fish food web, nutrient cycling, and contaminant processes in the southern basin of Lake Michigan. The model was used to examine possible effects of management actions and an exotic zooplankter (Bythotrephes) on Lake Michigan food web and contaminant dynamics. The model predicts that contaminant concentrations in salmonines will decrease by nearly 20% ifBythotrephes successfully establishes itself in the lake. The model suggests that this decrease will result from lowered transfer efficiencies within the food web and increased flux of contaminants to the hypolimnion. The model also indicates that phosphorus management will have little effect on contaminant concentrations in salmonines. The modeling exercise helped identify weaknesses in the data base (e.g., incomplete information on contaminant loadings and on the biomass, production, and ecological efficiencies of dominant organisms) that should be corrected in order to make reliable management decisions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02393827
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  • 2
    Electronic Resource
    Electronic Resource
    Reproductive styles and life history variables relative to exploitation and management ofSebastes stocks (1991)
    Springer
    Environmental biology of fishes 30 (1991), S. 253-271 
    Details
    ISSN: 1573-5133
    Keywords: Rockfish ; Longevity ; Reproductive value ; Fisheries ; Scorpaenidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The characteristics of lightly and heavily exploited Pacific ocean perch,Sebastes alutus, stocks are evaluated relative to the predictions of life history theory. These long-lived species (50–100 year lifespan) show limited phenotypic plasticity and have little buffering against the effects of reduced lifespan. Reduced stock abundance has generated some compensatory increase in growth rate. Length at first maturity varies only slightly with increased growth rate, although age at maturity may decrease by 1–4 years. Grooth increases yield larger (15–20%) size at age and increased reproductive effort at younger ages, but lower size-specific fecundity for these faster-growing fish. This suggests an energy allocation protocol favouring growth over reproduction in these long-lived animals. Rockfishes have late recruitment to fisheries (ages 10–15), and the detection time for results of management actions is equally long. Their vulnerability to overfishing means that indices of population changes, more representative of fishing effects than the catch rate index presently used, are required. Reproductive value indices are shown to be extremely sensitive and continuous with population abundance changes. Their incorporation into monitoring programs would permit more timely evaluation of management actions. Management policies developed for shorter-lived species are shown to be inappropriate for rockfishes. The need for an improved match in the time frame of the species' life history, and that of management strategies, is stressed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02296893
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  • 3
    Electronic Resource
    Electronic Resource
    Validated age and growth of the leopard shark, Triakis semifasciata, with comments on reproduction (1992)
    Springer
    Environmental biology of fishes 35 (1992), S. 187-203 
    Details
    ISSN: 1573-5133
    Keywords: California ; Elasmobranchs ; Exploitation ; Fisheries ; Life history ; Tagging ; Triakidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The age, growth, and sexual maturation of the leopard shark, Triakis semifasciata, from central California were studied. Growth band counts in vertebral centra of 162 leopard sharks produced von Bertalanffy growth curves with L∞, K. and to parameters of 1536 mm. 0.082, and -2.31, respectively, for both sexes combined. The L8 value for females (1602 mm TL) was slightly but insignificantly higher than for males (1499 mm TL), but the K and to values were almost identical. Seasonal changes in size modes of young-of-the-year leopard sharks, centrum edge characteristics, and growth and tetracycline mark-recapture from the field were used to validate annual deposition of vertebral centrum band pairs. Sexual maturity was evaluated by the gonads and presence of sperm and eggs; males mature at 7 yr and at about 63% of asymptotic length, and females mature at 10 yr, and at about 72% of asymptotic length. This slow growth, late maturity, and relatively low fecundity may increase their susceptibility to over-exploitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002193
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  • 4
    Electronic Resource
    Electronic Resource
    The barbs (Barbus spp.) of Lake Tana: a forgotten species flock? (1994)
    Springer
    Environmental biology of fishes 39 (1994), S. 1-22 
    Details
    ISSN: 1573-5133
    Keywords: Cyprinids ; Ethiopia ; Morphotypes ; Food-niche ; Biodiversity ; Feeding ; Evolution ; Fisheries ; Resource partitioning ; Piscivory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis In October–December 1990, the large barbs (Barbus) that contribute more than 35% of the catch in lake Tana (northern Ethiopia) were studied. Previous authors (Rüppell 1837, Boulenger 1902,1911, Bini 1940) described from 6 to 23 (sub)species for the lake. Banister (1973) lumped all of these into one subspecies: Barbus intermedius intermedius Rüppell,1837. We found that the Lake Tana Barbus could be readily categorized in at least 13 discrete morphotypes, some of which were already distinguished by local fishermen. None of the known descriptions are adequate to distinguish the barbs unambiguously, which is important for monitoring and management of developing fisheries. Intermediates between morphotypes were rare (〈 10%). By applying canonical discriminant analysis on a set of 17 morphometric characters (including some directly associated with feeding) our initial morphotype-distinction was confirmed. Also, differences between the morphotypes in distribution, related to depth and substratum were found, as well as differences in intestinal contents, a key to the food-niche. The high number of piscivorous morphotypes (8 out of 13) was striking as piscivory is relatively rare among cyprinids. Piscivory was found to be highly correlated with morphological (feeding related) characters. The presence of discrete morphotypes, that also differ in food-niche and distribution, strongly suggests that several distinct populations exist, that may be (partly or completely) reproductively segregated. Knowledge about these populations, that may represent separate units of fish stock, is of crucial importance for the management of sustainable fisheries and protection of the biodiversity in Lake Tana. It is possible that several species or even a unique cyprinid species flock are present, that urgently need protection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00004751
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  • 5
    Electronic Resource
    Electronic Resource
    The effects ofTilapia introductions in Lake Luhondo, Rwanda (1990)
    Springer
    Environmental biology of fishes 27 (1990), S. 303-308 
    Details
    ISSN: 1573-5133
    Keywords: Fish introductions ; Africa ; Cichlids ; Barbus ; Haplochromis ; Lake management ; Fisheries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis Cyprinid fishes apparently constituted the major part of the original fish fauna in Lake Luhondo, Rwanda, at least until 1934. At that time only three species, all cyprinids, were known from the lake:Barbus neumayeri, a small barbel, very common in the lake (described from the lake asBarbus luhondo) and two larger cyprinid species:Barbus microbarbis andVaricorhinus ruandae. These two large species were probably not very common in the lake. Between 1935 and 1938 some youngTilapia were introduced into Lake Luhondo. Since then and certainly since 1952 the large cyprinids seem to have disappeared completely from the lake. The smallBarbus neumayeri has become extremely rare; at present it survives only in some small tributaries of the lake. In the lake itselfTilapia andHaplochromis species are now the dominant fauna. A survey of the available information is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00002748
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  • 6
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    Premature p34cdc2 activation required for apoptosis (1994)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1994-02-25
    Description: Activation of the serine-threonine kinase p34cdc2 at an inappropriate time during the cell cycle leads to cell death that resembles apoptosis. Premature activation of p34cdc2 was shown to be required for apoptosis induced by a lymphocyte granule protease. The kinase was rapidly activated and tyrosine dephosphorylated at the initiation of apoptosis. DNA fragmentation and nuclear collapse could be prevented by blocking p34cdc2 activity with excess peptide substrate, or by inactivating p34cdc2 in a temperature-sensitive mutant. Premature p34cdc2 activation may be a general mechanism by which cells induced to undergo apoptosis initiate the disruption of the nucleus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shi, L -- Nishioka, W K -- Th'ng, J -- Bradbury, E M -- Litchfield, D W -- Greenberg, A H -- New York, N.Y. -- Science. 1994 Feb 25;263(5150):1143-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Manitoba Institute of Cell Biology, University of Manitoba, Winnipeg, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8108732" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; Animals ; *Apoptosis ; CDC2 Protein Kinase/*metabolism ; DNA Damage ; Deoxyribonucleases/pharmacology ; Enzyme Activation ; Enzyme Induction ; Membrane Glycoproteins/pharmacology ; Mice ; Mitosis ; Molecular Sequence Data ; Perforin ; Phosphorylation ; Pore Forming Cytotoxic Proteins ; Serine Endopeptidases/pharmacology ; Tumor Cells, Cultured
    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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  • 7
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    NGF and Alzheimer's: hopes and fears (1990)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1990-01-26
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Marx, J -- New York, N.Y. -- Science. 1990 Jan 26;247(4941):408-10.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2405484" target="_blank"〉PubMed〈/a〉
    Keywords: Alzheimer Disease/*drug therapy/metabolism ; Amyloid/metabolism ; Amyloid beta-Peptides ; Animals ; Clinical Trials as Topic ; Humans ; Nerve Growth Factors/adverse effects/*therapeutic use ; Recombinant Proteins
    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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  • 8
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    Better numbers on primate research (1990)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1990-03-30
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉New York, N.Y. -- Science. 1990 Mar 30;247(4950):1539.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/11642762" target="_blank"〉PubMed〈/a〉
    Keywords: *Animal Experimentation ; *Animal Welfare ; Animals ; Humans ; Literature ; *Primates ; *Statistics as Topic ; Substance-Related Disorders ; United States
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 9
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    A G protein mutant that inhibits thrombin and purinergic receptor activation of phospholipase A2 (1990)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1990-08-10
    Description: The stimulation of phospholipase A2 by thrombin and type 2 (P2)-purinergic receptor agonists in Chinese hamster ovary cells is mediated by the G protein Gi. To delineate alpha chain regulatory regions responsible for control of phospholipase A2, chimeric cDNAs were constructed in which different lengths of the alpha subunit of Gs (alpha s) were replaced with the corresponding sequence of the Gi alpha subunit (alpha i2). When a carboxyl-terminal chimera alpha s-i(38), which has the last 38 amino acids of alpha s substituted with the last 36 residues of alpha i2, was expressed in Chinese hamster ovary cells, the receptor-stimulated phospholipase A2 activity was inhibited, although the chimera could still activate adenylyl cyclase. Thus, alpha s-i(38) is an active alpha s, but also a dominant negative alpha i molecule, indicating that the last 36 amino acids of alpha i2 are a critical domain for G protein regulation of phospholipase A2 activity.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gupta, S K -- Diez, E -- Heasley, L E -- Osawa, S -- Johnson, G L -- DK37871/DK/NIDDK NIH HHS/ -- GM30324/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 1990 Aug 10;249(4969):662-6.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Basic Sciences, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/2166341" target="_blank"〉PubMed〈/a〉
    Keywords: Adenosine Triphosphate/pharmacology ; Animals ; Arachidonic Acid ; Arachidonic Acids/metabolism ; Cell Line ; Chlorides/pharmacology ; Enzyme Activation ; GTP-Binding Proteins/*genetics/metabolism ; Inositol Phosphates/metabolism ; Kinetics ; Lithium/pharmacology ; Lithium Chloride ; Macromolecular Substances ; *Mutation ; Phospholipases/*metabolism ; Phospholipases A/*metabolism ; Phospholipases A2 ; Receptors, Purinergic/drug effects/*physiology ; Restriction Mapping ; Thrombin/antagonists & inhibitors/*pharmacology ; Transfection
    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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  • 10
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    Functional evidence for an RNA template in telomerase (1990)
    American Association for the Advancement of Science (AAAS)
    Details
    Publication Date: 1990-02-02
    Description: The RNA moiety of the ribonucleoprotein enzyme telomerase from the ciliate Euplotes crassus was identified and its gene was sequenced. Functional analysis, in which oligonucleotides complementary to portions of the telomerase RNA were tested for their ability to prime telomerase in vitro, showed that the sequence 5' CAAAACCCCAAA 3' in this RNA is the template for synthesis of telomeric TTTTGGGG repeats by the Euplotes telomerase. The data provide a direct demonstration of a template function for a telomerase RNA and demarcate the outer boundaries of the telomeric template. Telomerase can now be defined as a specialized reverse transcriptase.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Shippen-Lentz, D -- Blackburn, E H -- New York, N.Y. -- Science. 1990 Feb 2;247(4942):546-52.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Molecular and Cell Biology, University of California, Berkeley 94720.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1689074" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Base Sequence ; Ciliophora/enzymology/*genetics ; DNA Nucleotidylexotransferase/*genetics ; Genes ; Molecular Sequence Data ; Oligonucleotide Probes ; RNA/*genetics ; Sequence Homology, Nucleic Acid ; *Templates, Genetic
    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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