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  • 1995-1999  (5)
  • 1940-1944
  • colonization  (3)
  • Gene duplication  (2)
  • 1
    ISSN: 1432-1432
    Keywords: Metalloproteinase ; Disintegrin ; Evolution ; Venom ; Phylogeny ; Gene duplication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The evolution of the Metalloproteinase Disintegrin Cysteine-rich (MDC) gene family and that of the mammalian Matrix-degrading Metalloproteinases (MMPs) are compared. The alignment of snake venom and mammalian MDC and MMP precursor sequences generated a phylogenetic tree that grouped these proteins mainly according to their function. Based on this observation, a common ancestry is suggested for mammalian and snake venom MDCs; it is also possible that gene duplication of the already-assembled domain structure, followed by divergence of the copies, may have significantly contributed to the evolution of the functionally diverse MDC proteins. The data also suggest that the structural resemblance of the zinc-binding motif of venom MDCs and MMPs may best be explained by common ancestry and conservation of the proteolytic motifs during the divergence of the proteins rather than through convergent evolution.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1432
    Keywords: Snake venom ; Bothrops ; Phospholipase ; Myotoxin ; Evolution ; cDNA ; Gene duplication ; Phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sequence coding for a snake venom phospholipase A2 (PLA2), BJUPLA2, has been cloned from a Bothrops jararacussu venom gland cDNA library. The cDNA sequence predicts a precursor containing a 16-residue signal peptide followed by a molecule of 122 amino acid residues with a strong sequence similarity to group II snake venom PLA2's. A striking feature of the cDNA is the high sequence conservation of the 5′ and 3′ untranslated regions in cDNAs coding for PLA2's from a number of viper species. The greatest sequence variation was observed between the regions coding for the mature proteins, with most substitutions occurring in nonsynonymous sites. The phylogenetic tree constructed by alignment of the amino acid sequence of BJUPLA2 with group II PLA2's in general groups them according to current taxonomical divisions and/or functional activity. It also suggests that gene duplications may have occurred at a number of different points during the evolution of snake venom group II PLA2's.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 313-314 (1995), S. 15-20 
    ISSN: 1573-5117
    Keywords: colonization ; rotifers ; zooplankton ; vagility ; dispersal ; metapopulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twelve new experimental ponds were constructed identically, filled simultaneously, had similar physical and chemical properties, and were maintained with minimal manipulation. Colonizing zooplankton communities were sampled bi-weekly for one year. Rotifers dominated zooplankton communities in densities, biomass, and species number (47 of 61 observed species were rotifers). Only 14 species were observed in all 12 ponds; 9 were rotifers. Twenty-nine species (26 rotifers) were recorded in 〈-6 ponds. Species with high vagility exhibited greater viability. Ponds differed in zooplankton community composition throughout the year, due to differences in both vagility and viability among colonizing species.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 287-388 (1998), S. 15-21 
    ISSN: 1573-5117
    Keywords: Rotifera ; zooplankton ; dispersal ; colonization ; wind ; rain ; waterfowl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zooplankton, and especially rotifers, have long been thought to be readily dispersed by wind, rain and animals (especially waterfowl). Given that premise, local processes (tolerance to abiotic conditions, biotic interactions) have been the main focus of ecological studies. We tested the premise of high dispersal rates by incubating particulates collected with windsocks and rain samplers at two sites over 1 year. The sites were 80 km apart and differed in proximity to water and surrounding terrain. We also incubated fecal material of wild ducks. Pond sediments were identically incubated as a test of incubation method. Only bdelloid rotifers were collected in wind samples, and only four rotifer species were collected in rain samples: Lecane leontina, Lecane closterocerca, Keratella cochlearis, and a bdelloid. No metazoans were found in incubated duck feces, yet incubated pond sediments yielded 11 rotifer, one copepod, four cladoceran, and three ostracod species. Our results do not support the premise of readily dispersed zooplankton. If zooplankton dispersal is infrequent and limited to few species, a series of other questions should be addressed on processes regulating zooplankton population dynamics and community composition.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 387-388 (1998), S. 15-21 
    ISSN: 1573-5117
    Keywords: Rotifera ; zooplankton ; dispersal ; colonization ; wind ; rain ; waterfowl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zooplankton, and especially rotifers, have long been thought to be readily dispersed by wind, rain and animals (especially waterfowl). Given that premise, local processes (tolerance to abiotic conditions, biotic interactions) have been the main focus of ecological studies. We tested the premise of high dispersal rates by incubating particulates collected with windsocks and rain samplers at two sites over 1 year. The sites were 80 km apart and differed in proximity to water and surrounding terrain. We also incubated fecal material of wild ducks. Pond sediments were identically incubated as a test of incubation method. Only bdelloid rotifers were collected in wind samples, and only four rotifer species were collected in rain samples: Lecane leontina, Lecane closterocerca, Keratella cochlearis, and a bdelloid. No metazoans were found in incubated duck feces, yet incubated pond sediments yielded 11 rotifer, one copepod, four cladoceran, and three ostracod species. Our results do not support the premise of readily dispersed zooplankton. If zooplankton dispersal is infrequent and limited to few species, a series of other questions should be addressed on processes regulating zooplankton population dynamics and community composition.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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