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  • Springer  (11)
  • The American Society for Biochemistry and Molecular Biology (ASBMB)  (2)
  • AGU (American Geophysical Union)  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Importance of life cycle events in the population dynamics of Gonyaulax tamarensis (1983)
    Springer
    Marine biology 76 (1983), S. 179-189 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Life cycle changes that allow populations of the toxic dinoflagellate Gonyaulax tamarensis Lebour to inhabit the benthos and the plankton alternately are important factors regulationg the initiation and decline of blooms in restricted embavments. When the dynamics of these estuarine populations were monitored during “bloom” and “non bloom” years, it was shown that: (1) each year, germination of benthie cysts inoculated the overlying waters during the vernal warming period, but a large residual population remained in the sediments throughout the blooms; (2) the resulting planktonic population began growth under suboptimal temperature conditions; (3) the populations developed from this inoculum through asexual reproduction until sexuality (and cyst formation) were induced; (4) encystment was not linked to any obvious environmental cue and occurred under apparently optimal conditions; and (5) an increase in the number of non-mitotic swimming cells (planozygotes, the precursors to dormant cysts) accompanied the rapid decline of the planktonic population. Thus encystment, in combination with hypothesized losses due to advection and grazing, contributed substantiatly to the decline of the vegetative cell population. We conclude that the encystment/excystment cycle temporally restricts the occurrence of the vegetative population and may not be optimized for rapid or sustained vegetative growth and bloom formation in shallow embayments. The factors that distinguish “bloom” from “non-bloom” years thus appear to be operating on the growth of the planktonic population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392734
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  • 2
    Electronic Resource
    Electronic Resource
    The analysis of water in the Martian regolith (1979)
    Springer
    Journal of molecular evolution 14 (1979), S. 33-38 
    Details
    ISSN: 1432-1432
    Keywords: Water ; Mars ; Adsorbed water ; Capillary water ; Mineral hydrates-hygroscopic minerals ; Endolithic organisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary One of the scientific objectives of the Viking Mission to Mars was to accomplish an analysis of water in the Martian regolith. The analytical scheme originally envisioned was severly compromised in the latter stages of the Lander instrument package design. Nevertheless, a crude soil water analysis was accomplished. Samples from each of the two widely separated sites yielded roughly 1 to 3% water by weight when heated successively to several temperatures up to 500°C. A significant portion of this water was released in the 200° to 350°C interval indicating the presence of mineral hydrates of relatively low thermal stability, a finding in keeping with the low temperatures generally prevailing on Mars. The presence of a duricrust at one of the Lander sites is taken as possible evidence for the presence of hygroscopic minerals on Mars. The demonstrated presence of atmospheric water vapor and thermodynamic calculations lead to the belief that adsorbed water could provide a relatively favorable environment for endolithic organisms on Mars similar to types recently discovered in the dry antarctic deserts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01732365
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  • 3
    Electronic Resource
    Electronic Resource
    High-frequency stable transformation of cotton (Gossypium hirsutum L.) by particle bombardment of embryogenic cell suspension cultures (2000)
    Springer
    Plant cell reports 19 (2000), S. 539-545 
    Details
    ISSN: 1432-203X
    Keywords: Key words Biolistic transformation ; Cotton ; Embryogenic cell suspension ; Gossypium hirsutum ; Stable expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Stable transformation of cotton (Gossypium hirsutum L.) at a high frequency has been obtained by particle bombardment of embryogenic cell suspension cultures. Transient and stable expression of the β-glucuronidase (GUS) gene was monitored in cell suspension cultures. Transient expression, measured 48 h after bombardment, was abundant, and stable expression was observed in over 4% of the transiently expressing cells. The high efficiency of stable expression is due to the multiple bombardment of rapidly dividing cell suspension cultures and the selection for transformed cells by gradually increasing the concentrations of the antibiotic Geneticin (G418). Southern analysis indicated a minimum transgene copy number of one to four in randomly selected plants. Fertile plants were obtained from transformed cell cultures less than 3 months old. However, transgenic and control plants from cell cultures older than 6 months produced plants with abnormal morphology and a high degree of sterility.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050770
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  • 4
    Electronic Resource
    Electronic Resource
    Toxic phytoplankton blooms in the southwestern Gulf of Maine: testing hypotheses of physical control using historical data (1992)
    Springer
    Marine biology 112 (1992), S. 165-174 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Blooms of the toxic dinoflagellate Alexandrium tamarense Lebour have been nearly annual features along the coasts of southern Maine, New Hampshire and Massachusetts, USA, since 1972. In 1990 two hypotheses which have been used to explain the initiation of these blooms in the southwestern portion of the Gulf of Maine were tested using historical records of shellfish toxicity, wind, and river flow. The first hypothesis states that the blooms were initiated or advected to shore by wind-driven coastal upwelling. The second states that established blooms were advected from north to south alongshore in a coastally trapped buoyant plume of water. Of the eleven years examined (1979 to 1989), we found seven cases inconsistent with the wind-driven upwelling hypothesis, and only one case (1985) which contradicts the plume-advection hypothesis. 1985 was an unusual year in many respects, and we suggest that some other mechanism was responsible for the toxic outbreaks. In addition, the wind-driven upwelling hypothesis could not explain the observed north-to-south temporal progression of toxicity each year. The plume-advection hypothesis was found to best explain the datails of the timing and spread of shellfish toxicity in Gulf of Maine waters to the south of Penobscot Bay, Maine. These include the variable north-to-south progression with time, the presence of a toxin-free zone south of Cape Ann, Massachusetts, the sporadic nature of toxic outbreaks south of Massachusetts Bay, and the apparently rare occurrence of high toxicity levels well offshore on Nantucket Shoals and Georges Bank.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349740
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  • 5
    Electronic Resource
    Electronic Resource
    Biogeography of toxic dinoflagellates in the genusAlexandrium from the northeastern United States and Canada (1994)
    Springer
    Marine biology 120 (1994), S. 467-478 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twenty-eight strains of toxic dinoflagellates in the genusAlexandrium from the northeastern United States and Canada were characterized on the basis of morphology, bioluminescence capacity, mating compatibility, and toxin composition. The distributions of these characters were evaluated in the context of regional patterns of paralytic shellfish poisoning (PSP) and coastal hydrography. Two morphospecies were identified-A. tamarense Lebour andA. fundyense Balech. The two are interspersed geographically though there are areas, such as the Gulf of Maine, where apparently onlyA. fundyense occurs. Southern waters (Cape Cod, Connecticut, and Long Island) have especially diverse populations. The two species are sexually compatible. Virtually all northern isolates are bioluminescent, whereas southern isolates include bioluminescent and non-bioluminescent strains. Cluster analyses, based on high performance liquid chromatography (HPLC) determinations of the suite of toxins produced by each isolate, revealed two and perhaps three distinct groups. One is comprised almost exclusively of northern strains, and the other of southern strains. A Cape Cod cluster may be separable from the southern group. These analyses explain a previously reported north-to-south trend of decreasing toxicity, as the northern isolates produce greater proportions of the more potent toxins than do southern forms. The overall perspective is that the biogeography of toxicAlexandrium spp. in the study region is not that of a single, widespread, homogeneous population, but rather is comprised of several sub-populations, each with its own physiological characteristics and history. Two scenarios are considered with respect to this regional biogeography. The first invokes recent and continuing dispersal of isolates to the south from a center of origin in the north, followed by recombination and strong selection. The second holds that the northern and southern populations diverged from a common ancestor (vicariance), but now represent localized populations with little mixing of genotypes. Neither hypothesis can be completely refuted by the data presented here, though the weight of the evidence favors the latter. The correct scenario may be a combination of both, with recent and continuous speading occuring within the Gulf of Maine and perphaps the Gulf of St. Laerence, but with endemic localized populations persisting without genetic exchange in most southern locations. These data also indicate that although morphological criteria separate toxicAlexandrim isolates from the study region into two morphospecies, these assignments do not coincide with clusterings based on toxin composition or allozyme electrophoresis, and they are further violated by mating results. A revision of taxon designations to the varietal level could be justified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00680222
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  • 6
    Electronic Resource
    Electronic Resource
    Variation among congeneric dinoflagellates from the northeastern United States and Canada (1989)
    Springer
    Marine biology 101 (1989), S. 427-435 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Relationships among dinoflagellates of the genus Alexandrium (=Protogonyaulax) from Long Island, New England, USA, and northeastern Canada were investigated between 1983 and 1987 using enzyme electrophoresis. A relative lack of heterogeneity among toxic isolates was observed despite large geographic separations of source populations. This observation is in marked contrast to observations on toxic members of this genus from the west coast of Canada and the United States. These different enzyme variability patterns support the proposal that dispersal of toxic strains in the east from a common source has occurred recently, presumably from established populations in northern Maine, USA, or Canada. Non-toxic strains from the study area were only distantly related to toxic isolates, consistent with their different morphology and separate species designations. One non-toxic isolate from a different region, that is conspecific with a number of the toxic strains, was more similar to these isolates than to other non-toxic clones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00541643
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  • 7
    Electronic Resource
    Electronic Resource
    Dynamics and physiology of saxitoxin production by the dinoflagellatesAlexandrium spp. (1990)
    Springer
    Marine biology 104 (1990), S. 511-524 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Toxin content (fmol cell−1) and a suite of elemental and macromolecular variables were measured in batch cultures of the dinoflagellatesAlexandrium fundyense, A. tamarense andAlexandrium sp. from the southern New England region, USA. A different perspective was provided by semicontinuous cultures which revealed sustained, steady-state physiological adaptations by cells to N and P limitation. Two types of variability were investigated. In batch culture, changes in nutrient availability with time caused growth stage variability in toxin content, which often peaked in mid-exponential growth. A second type of variability that could be superimposed on growth stage differences is best exemplified by the high toxin content of cells grown at suboptimal temperatures. Calculations of the net rate of toxin production (R tox ; fmol cell−1 d−1) for these different culture treatments and modes made it possible to separate the dynamics of toxin production from cell division. Over a wide range of growth rates, cells produced toxin at rates approximating those needed to replace “losses” to daughter cells during division. The exception to this direct proportionality was with P limitation, which was associated with a dramatic increase in the rate of toxin production as cells stopped dividing due to nutrient limitation in batch culture. Growth stage variability in batch culture thus reflects small imbalances (generally within a factor of two) between the specific rates of toxin production and cell division. N limitation and CO2 depletion both affect pathways involved in toxin synthesis before those needed for cell division; P limitation does the opposite. The patterns of toxin accumulation were the same as for major cellular metabolites or elemental pools. The highest rates of toxin production appear to result from an increased availability of arginine (Arg) within the cell, due to either a lack of competition for this amino acid from pathways involved in cell division or to increased de novo synthesis. There were no significant changes in toxin content with either acclimated growth at elevated salinity, or with short term increases or decreases of salinity. These results demonstrate that toxin production is a complex process which, under some conditions, is closely coupled to growth rate; under other conditions, these processes are completely uncoupled. Explanations for the observed variability probably relate to pool sizes of important metabolites and to the differential response of key biochemical reactions to these pool sizes and to environmental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01314358
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  • 8
    Electronic Resource
    Electronic Resource
    Alongshore transport of a toxic phytoplankton bloom in a buoyancy current: Alexandrium tamarense in the Gulf of Maine (1992)
    Springer
    Marine biology 112 (1992), S. 153-164 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined the mechanisms controlling blooms of the toxic dinoflagellate Alexandrium tamarense Lebour and the concomintant patterns of shellfish toxicity in the southwestern Gulf of Maine, USA. During a series of cruises from 1987 to 1989, hydrographic parameters were measured to elucidate the physical factors affecting the distribution and abundance of dinoflagellates along this coast. In 1988 and 1989 when toxicity was detected in the southern part of this region, A. tamarense cells were apparently transported into the area between Portsmouth, New Hampshire, and Cape Ann, Massachusetts, in a coastally trapped buoyant plume. This plume appears to have been formed by the outflow from the Androscoggin and Kennebec Rivers. Flow rates of these rivers, hydrographic sections, and satellite images led us to conclude that the plume persisted for about a month, and extended alongshore for several hundred kilometers. The distribution of cells followed the position of the plume as it was influenced by wind and topography. When winds were downwelling-favorable (to the southwest), cells were moved alongshore to the south, and were held to the coast; when winds were upwelling-favorable (to the northeast),the plume sometimes separated from the coast, advecting the cells offshore. In 1987 when no plume was present, A. tamarense cells were scarce, and no toxicity was recorded at the southern stations. The alongshore advection of toxic cells within a coastally trapped buoyant plume can explain the details of the temporal and spatial patterns of shellfish toxicity along the coast. We hypothesize that (1) the source of the A. tamarense populations is in the north, possibly associated with the Androscoggin and Kennebec estuaries, that (2) toxicity patterns follow a predictable relationship with river flow volume and timing of flow peaks and that (3) wind stresses directly influence the distribution of low salinity water and the dinoflagellate cells. Local, in situ growth of dinoflagellates can be an important factor initiating toxic dinoflagellate blooms. However, these data demonstrate the significant role of alongshore transport of established populations of A. tamarense in controlling the location and timing of paralytic shellfish poisoning (PSP) outbreaks in May and June along the southwestern coast of the Gulf of Maine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349739
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  • 9
    Electronic Resource
    Electronic Resource
    Nucleotide sequence of a gene encoding an organophosphorus nerve agent degrading enzyme from Alteromonas haloplanktis (1997)
    Springer
    Journal of industrial microbiology and biotechnology 18 (1997), S. 49-55 
    Details
    ISSN: 1476-5535
    Keywords: Keywords: Alteromonas organophosphorus acid anhydrolase gene; X-Pro dipeptidase; sequencing and functional homology to prolidase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Organophosphorus acid anhydrolases (OPAA) catalyzing the hydrolysis of a variety of toxic organophosphorus cholinesterase inhibitors offer potential for decontamination of G-type nerve agents and pesticides. The gene (opa) encoding an OPAA was cloned from the chromosomal DNA of Alteromonas haloplanktis ATCC 23821. The nucleotide sequence of the 1.7-kb DNA fragment contained the opa gene (1.3 kb) and its flanking region. We report structural and functional similarity of OPAAs from A. haloplanktis and Alteromonas sp JD6.5 with the enzyme prolidase that hydrolyzes dipeptides with a prolyl residue in the carboxyl-terminal position. These results corroborate the earlier conclusion that the OPAA is a type of X-Pro dipeptidase, and that X-Pro could be the native substrate for such an enzyme in Alteromonas cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/sj.jim.2900358
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  • 10
    Electronic Resource
    Electronic Resource
    Relationship of Tarbush Leaf Surface Terpene Profile with Livestock Herbivory (1998)
    Springer
    Journal of chemical ecology 24 (1998), S. 1-12 
    Details
    ISSN: 1573-1561
    Keywords: Flourensia cernua ; leaf surface chemistry ; diet selection ; epicuticular wax ; monoterpenes ; sesquiterpenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Tarbush (Flourensia cernua DC.) is a Chihuahuan Desert shrub with a resinous leaf surface containing terpenes that may affect livestock herbivory. Cattle, sheep, and goats were densely stocked in paddocks containing tarbush in two consecutive years for six to nine days and defoliation of 160 plants was recorded daily. Plants were categorized as exhibiting high or low defoliation. Leaves were collected from these plants the third year for chemical analysis. A selection procedure was used to generate two variable sets closely related to defoliation category. One set contained 14 variables (dry matter, ash, α-pinene, sabinene, 3-carene, p-cymene, limonene, camphor, borneol, cis-jasmone, β-caryophyllene, α-humulene, ledene, and flourensadiol) and the other set contained 14 unidentified compounds. When subjected to multivariate analysis, each group distinguished between the two defoliation categories (P 〈 0.001 and P 〈 0.0019 for known and unknown variable sets, respectively). These data support the hypothesis that leaf surface chemistry of individual tarbush plants is related to extent of defoliation by livestock.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022399426352
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