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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 398-399 (1999), S. 375-383 
    ISSN: 1573-5117
    Keywords: coastal pollution ; copper pollution ; heavy metals ; macroalgae ; Lessonia ; L. nigrescens ; L. trabeculata ; ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plants of Lessonia trabeculata and L. nigrescens were studied by transmission electron microscopy in order to evaluate ultrastructural level changes in response to copper exposure. Samples of fronds, stipes, and holdfasts were collected from areas with and without copper mining discharges. Changes in cell ultrastructure observed in Lessonia trabeculata were related to copper concentrations in seawater, seaweeds and extracted alginates. The results strongly suggest that tolerance or adaptation of Lessonia to high concentrations of copper is the capacity of different plant tissues to accumulate copper as precipitates, primarily at two levels: the cell wall and periplasmalemmal space, with the vacuolar system being a third site.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5117
    Keywords: algal holdfasts ; Peracarida ; reproduction ; dispersion ; benthos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During the colonisation process of islands, newly immigrating species often arrive as single individuals. Islands that have received single colonisers may subsequently harbour large populations of a species, while other islands may completely lack this species. Exchange between islands is limited, thereby strongly affecting evolutionary processes. While this concept is widely used in the context of oceanic islands or habitat patches on the mainland, it is rarely used to explain and examine the distribution patterns of marine invertebrates. Benthic marine organisms inhabiting patches with island-like features may also be restricted in their movements between patches. Once established in a patch, it may be more favourable to remain there rather than moving to another patch. Juveniles of species with direct development may recruit to the island patch of their parents. Herein, we examined the peracarid fauna in patches that have island-like features, i.e. kelp holdfasts. The number of peracarid species within an individual holdfast increased with its size. Similarly, the number of individuals per holdfast increased with holdfast size. However, several peracarid species showed a strongly aggregated distribution pattern, being highly abundant in some holdfasts and almost completely absent in others. Our results suggest that these aggregations of conspecifics may be a consequence of the peracarid reproductive biology: fully developed juveniles emerge from the female's marsupium and recruit to the immediate vicinity of their mother, showing little or no tendency to emigrate towards other patches. At present, while it is not known how long peracarid aggregations within kelp holdfasts persist, our data suggest that some juveniles may remain with the natal holdfast and possibly reproduce therein. It is concluded that, during certain time periods, reproduction rates of peracarids in a holdfast may exceed their migration rates between holdfasts.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5028
    Keywords: circadian rhythm ; embryogeny ; germin ; globulin ; oxalate oxidase ; seed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Wheat germin is a protein expressed during germination which possesses an oxalate oxidase activity. Germin-type oxalate oxidases have been extensively studied in monocotyledons (wheat and barley) where they are thought to have important functions for development, stress response and defence against pathogens. In contrast, almost nothing is known about the germin-like proteins found in dicotyledons, gymnosperms and myxomycetes. In this work, cDNA clones for three genes (ATGER1, ATGER2 and ATGER3) encoding germin-like proteins, initially characterized as expressed sequence tags (ESTs), from Arabidopsis thaliana cDNA libraries were further characterized. In addition, we isolated and sequenced a Brassica napus cDNA which was strongly homologous to the cDNA for ATGER1. Sequence analysis and secondary structure predictions of the proteins encoded by these cDNAs showed that they possess all the characteristic features of members of the germin family and of the germin/seed globulins/sucrose binding protein superfamily. Sequence comparisons and mapping demonstrated the existence of at least two different gene families in the A. thaliana genome encoding a minimum of three genes for germins. These three genes have been mapped in three different location on the Arabidopsis genome. By northern blot hybridizations we found that these genes are differentially regulated. ATGER1 was expressed during germination, like wheat germin, but also in leaves whereas ATGER2 transcripts were exclusively found in developing embryos, like wheat pseudo-germin. ATGER3 mRNAs were found in leaves and flowers and their abundance was shown to vary during the circadian cycle.
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  • 4
    ISSN: 1573-5028
    Keywords: Brassica napus ; cold acclimation ; gene isolation ; human tumour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to identify genes involved in cold acclimation, we have constructed a cDNA library from Brassica napus (cv. Samouraï) cold-acclimated etiolated seedlings. By differential screening, a cDNA clone named pBnC24 (Brassica napus Cold), corresponding to a new cold-inducible plant gene, was isolated. Northern blot hybridizations using total RNA from acclimated and unacclimated seedlings confirmed that BnC24 represents a cold-regulated gene. In contrast with a number of cold-inducible plant genes, BnC24 does not seem to be responsive to abscisic acid (ABA). In addition, further screening of the ‘cold-acclimated’ cDNA library using pBnC24 cDNA as a probe, allowed the isolation of a second type of homologous cDNA. Sequence analysis showed that the two BnC24 genes encode basic 24 kDa proteins, which are highly hydrophilic and rich in alanine, lysine and arginine. The nucleotide and deduced amino acid sequences of these clones do not show any homology with other previously described cold-induced plants genes. However they have strong homology with a recently discovered human tumour gene, bbc1 (breast basic conserved), which seems to be highly conserved in eukaryotes.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 204-205 (1990), S. 41-47 
    ISSN: 1573-5117
    Keywords: ecological effects ; harvesting ; kelp ; Lessonia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lessonia nigrescens and L. trabeculata are economically important canopy-forming kelps in Chile. Experimental harvesting of stipes above the first dichotomy reduces stipe movement and inter-stipe friction, allowing the development of a heavy epiphytic load and increased grazing. Complete stipe removal leads to holdfast death as neither species is able to simultaneously regenerate all stipes. The invertebrate fauna inside the holdfast does not respond to upper canopy changes, but mortality does occur in partial or complete plant removals. Kelp removal also affects inter-plant distances, results in increased access of grazers to the outside and inside of kelp holdfasts, reduces recruitment of other algal species, and modifies the morphology of L. trabeculata such that the plants become more susceptible to removal by water movement.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 260-261 (1993), S. 313-320 
    ISSN: 1573-5117
    Keywords: Biological ; educational ; economic ; social ; and management factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A number of factors influenced yield from natural beds of marine algae in Chile. These factors are related not only to biological and ecological knowledge of the algal resource, but also to external events, such as; (1) the pressure of international markets for raw material, (2) unemployment level of coastal workers, which increases the number of seasonal harvesters, (3) the low level of regulation enforcement along Chile's extensive coast, (4) the low level of education and income of algal harvesters, and (5) except for Gracilaria, the lack of a management plan for algal resources.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 326-327 (1996), S. 327-333 
    ISSN: 1573-5117
    Keywords: algae ; bioindicators ; Chile ; coastal environment ; mining pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twelve seaweed species were sampled from 1991 to 1993 in order to detect the impact of natural mineralization and mining in 14 contaminated and non-contaminated areas (between 24° and 30° S — more than 1200 km) along the northern Chilean coast. Instrumental neutron activation analysis (INAA) was used to measure the concentration of 17 chemical elements. The results showed high variability in and between species, among sampling sites and times of collection. The high values of heavy metals in seaweeds suggest that these marine organisms can be used as biological indicators for detecting mineralization and anthropogenic impact on coastal marine communities.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied phycology 7 (1995), S. 347-349 
    ISSN: 1573-5176
    Keywords: Lessonia ; northern Chile ; repopulation ; intertidal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Intertidal rocky areas in northern Chile were repopulated experimentally with the brown alga Lessonia nigrescens using spore seeding and placement of reproductive fronds. The results were successful, and it is suggested that methods developed in the field can be done by people without special training.
    Type of Medium: Electronic Resource
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  • 9
    Publication Date: 2016-11-14
    Description: Kelp forests (Order Laminariales) form key biogenic habitats in coastal regions of temperate and Arctic seas worldwide, providing ecosystem services valued in the range of billions of dollars annually. Although local evidence suggests that kelp forests are increasingly threatened by a variety of stressors, no comprehensive global analysis of change in kelp abundances currently exists. Here, we build and analyze a global database of kelp time series spanning the past half-century to assess regional and global trends in kelp abundances. We detected a high degree of geographic variation in trends, with regional variability in the direction and magnitude of change far exceeding a small global average decline (instantaneous rate of change = −0.018 y−1). Our analysis identified declines in 38% of ecoregions for which there are data (−0.015 to −0.18 y−1), increases in 27% of ecoregions (0.015 to 0.11 y−1), and no detectable change in 35% of ecoregions. These spatially variable trajectories reflected regional differences in the drivers of change, uncertainty in some regions owing to poor spatial and temporal data coverage, and the dynamic nature of kelp populations. We conclude that although global drivers could be affecting kelp forests at multiple scales, local stressors and regional variation in the effects of these drivers dominate kelp dynamics, in contrast to many other marine and terrestrial foundation species.
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 10
    Publication Date: 1996-07-01
    Print ISSN: 0018-8158
    Electronic ISSN: 1573-5117
    Topics: Biology
    Published by Springer
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