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  • 1995-1999  (3)
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  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Seven colonies of Lobophytum compactum Tixier-Durivault, 1956, which produce isolobophytolide as the major secondary metabolite, were selected from a fringing reef in the Pelorus Channel, Palm Island Group (18°34′S; 146°29′E), North Queensland, Australia. In September 1991, they were sectioned to afford two portions which were relocated to a grid, and a significant part of the parent colony which was left in place. The aim of the experiment was to determine the effect of relocation and contact with a toxic alga on the secondary metabolite content of a soft coral. A significant increase in the concentration of isolobophytolide was observed for all relocated colonies (n=14, p=0.001) compared to the non-relocated control colonies. This decreased after 2 mo, and was not significantly different from that of the non-relocated control colonies (n=14, p=0.881). After 1 mo, Plocamium hamatum J. Agardh plants were placed in direct contact with 50% of the relocated colonies. All soft-coral colonies in contact with the alga (n=7), showed tissue necrosis on the parts in direct contact with the alga after a further 2 wk. Tissues of the relocated control colonies (n=7), and those portions of treated colonies which were not in direct contact with the alga, were not affected. The parts of the colonies in contact with the alga showed a significant decrease in lipid content over time (n=7, p=0.001) and also a decrease in the concentration of the diterpene isolobophytolide (n=7, p=0.001). The effects of P. hamatum on the soft coral were essentially restricted to contract necrosis; chemical variations in the affected tissue were the outcomes of this necrosis. These results indicate that stress due to relocation is a more important factor in the variation of isolobophytolide levels in the soft coral L. compactum than is contact with the alga P. hamatum.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The eggs of Lobophytum crassum Von Marenzeller, 1886, collected at Magnetic Island (19°10′S; 146°52′E) in October or November between 1983 and 1993, contained significant amounts (6% dry weight) of (-)-epi-thunbergol, in addition to other terpenoid metabolites also present in the parent colony. (-)-Epi-thunbergol was not present in the tissues of the releasing colony. Using fluorocarbon droplets impregnated with the chemotactic molecules and a videomicroscopic technique for the direct observation of sperm under the influence of attractant molecules, we showed that (-)-epi-thunbergol, whether isolated from L. crassum or from a gorgonian octocoral (Briareum sp.), significantly attracts sperm from L. crassum colonies. Attraction could be detected using direct observation at concentrations as low as 3.25 μg ml-1. This is the first evidence for sperm chemotaxis in the Alcyonacea. Eggs from L compactum, a common alcyonacean coral at Orpheus Island (18°36′S; 146°29′E) contained (-)-thunbergol as the egg-specific compound. L. compactum was not found at Magnetic Island. (-)-Thunbergol from L. compactum and (+)-thunbergol from a Douglas fir tree both showed levels of attraction similar to (-)-epi-thunbergol against L. crassum sperm. Although L. crassum sperm were apparently neither stereo- nor enantio-specific in their selectivity for chemotactic molecules, (-)-epi-thunbergol was identified as the natural sperm attractant in the eggs of L. crassum.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1777
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Gene mapping in cattle has progressed rapidly in recent years largely owing to the introduction of powerful genetic markers, such as the microsatellites, and through advances in physical mapping techniques such as synteny mapping and fluorescence in situ hybridization (FISH). Microsatellite markers are often not physically mapped because they are generally isolated from small insert plasmid libraries, which makes their chromosomal localization inefficient. In this report we describe the FISH mapping of a large group of cosmid-derived bovine microsatellite markers, as our contribution to the European mapping initiative, BovMap. One objective of BovMap is to develop a set of anchored loci for the cattle genome map. Two cosmid libraries were screened with probes corresponding to the (AC) n microsatellite motif. Positive clones were mapped by FISH, and then a subset was further analyzed by sequencing the region flanking the microsatellite repeat. In total, 58 clones were hybridized with chromosomes and identified loci on 22 of the 31 different bovine chromosomes. Three clones contained satellite DNA. Two or more markers were placed on 12 chromosomes. Sequencing of the microsatellites and flanking regions was performed directly from 43 cosmids, as previously reported (Ferretti et al. Anim. Genet. 25, 209–214, 1994). Primers were developed for 39 markers and used to describe the polymorphism associated with the corresponding loci.
    Type of Medium: Electronic Resource
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