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  • Springer  (198)
  • Wiley-Blackwell  (38)
  • American Association for the Advancement of Science (AAAS)
  • 1
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A stereophotographic technique for determining size and relative position of free-swimming sharks is described and illustrated for schooling scalloped hammerhead sharks (Sphyrna lewini). The method yields total length and nearest-neighbor, interindividual distance; and each of these dimensions is expressed as a function of the shark's distance into a school on the vertical and horizontal planes. Stereopairs of photographs were taken by an aligned, beam-mounted pair of cameras (Nikonos III). The scale to determine the length of a shark from the paired photographic images was obtained from the horizontal displacement between the images. Displacement was correlated with optical axis separation from photographs of a scaled staff at known distances from the camera. Image dimensions on the photographs were measured by projecting a scale onto the stage through a camera lucida. The precision of repeated measurements of a 50 cm section of a scaled staff at increasing distances from the cameras of 2, 4, and 8 m was ≦±5.0%. Lengths of the sharks ranged from 109 to 371 cm, with a median of 178 cm, for 3 offshore sites in the Gulf of California during July and August 1979. At one site, El Bajo Gorda, lengths increased with both distance from the camera and distance into the group; in contrast, the interindividual distances (head-to-head) did not vary with distance into the group and possessed a median of 232 cm.
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  • 2
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Monocerin is a benzopyran fungal toxin with broad activity on plants, fungi and insects. Its effect upon cell cycle progression has been analyzed in maize roots. Meristematic cells were synchronized by treatment with aphidicolin. Flow cytometric DNA analysis and mitotic indices indicated durations of 1.5 h, 5 h, 2 h and 1 h for respectively G1, S, G2 and M phases of the normal cell cycle at 25°C. Treatment of these synchronized meristems with 0.5 mM monocerin during release after an aphidicolin block produced a short delay in S phase and then a more important delay (about 2.5 h) in entry into mitosis. Treatments for similar durations (3 h) during progression through the cycle revealed two periods of action of monocerin. The first appears to be mid to late S and the second one G2, before the transition point between G2 and M. Action on either one of these target periods could lead to a delay in the G2/M transition, but these two responses did not appear to be additive.
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  • 3
    ISSN: 1432-203X
    Keywords: Wheat ; transformation ; glyphosate ; CP4/GOX ; embryos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The lack of alternative selectable markers in crop transformation has been a substantial barrier for commercial application of agricultural biotechnology. We have developed an efficient selection system for wheat transformation using glyphosate-tolerant CP4 and GOX genes as a selectable marker. Immature embryos of the wheat cultivar Bobwhite were bombarded with two separate plasmids harboring the CP4/GOX and GUS genes. After a 1 week delay, the bombarded embryos were transferred to a selection medium containing 2 mM glyphosate. Embryo-derived calli were subcultured onto the same selection medium every 3 weeks consecutively for 9–12 weeks, and were then regenerated and rooted on selection media with lower glyphosate concentrations. Transgenic plants tolerant to glyphosate were recovered. ELISA assay confirmed expression of the CP4 and GOX genes in R0 plants. Southern blot analysis demonstrated that the transgenes were integrated into the wheat genomes and transmitted to the following generation. The use of CP4 and GOX genes as a selectable marker provides an efficient, effective, and alternative transformation selection system for wheat.
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  • 4
    ISSN: 1432-203X
    Keywords: Key wordsCasuarina glauca ; Gymnostoma deplancheana ; Allocasuarina verticillata ; Actinorhizal plants ; Frankia symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genome size and base composition of diploid plant species from three genera of the Casuarinaceae family were determined by flow cytometry. Casuarina glauca Sieb. ex Spring. and Gymnostoma deplancheana (Miq.) L. Johnson showed a small genome with 2C = 0.70 pg, 58.6% AT, 40.5% GC for the first species and 2C = 0.75 pg, 58.7% AT, 40.5% GC for the second. Allocasuarina verticillata (Lam.) L. Johnson had a larger genome: 2C = 1.90 pg, 59.3% AT, 41.1% GC. One haploid genome of C. glauca is therefore about 340×106 base pairs. In leaves, roots or bark of these three species, polysomaty was virtually absent: a maximum frequency of 4C nuclei of only 0.08 was found in bark of C. glauca. The genome sizes of C. glauca and G. deplancheana are among the smallest described for higher plants. Small genome size, diploidy and the absence of polysomaty are advantageous traits for facilitating molecular approaches to improvement of these actinorhizal plants and developing the study of their symbiotic interactions with Frankia.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 77 (1989), S. 295-303 
    ISSN: 1432-2242
    Keywords: Chromosomes ; Flow cytometry ; Theoretical flow karyotypes ; Spreadsheet software
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Theoretical flow karyotypes from both plant and mammalian species have been simply modelled using computer spreadsheet software. The models are based upon published values of relative DNA content or relative lengths of each of the chromosomes. From such data, the histograms of chromosome distribution have been simulated for both linear and logarithmic modules of a flow cytometer, and as a function of the coefficient of variation. Simulated and experimental histograms are compard for Nicotiana plumbaginifolia. This readily accessible exercise facilitates the planning and execution of flow cytometric analysis and sorting of chromosomes.
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  • 6
    ISSN: 1432-2242
    Keywords: Microsatellite ; Germplasm ; Genetic resources ; Genetic analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Simple sequence repeats (SSRs), also known as microsatellites, are highly variable DNA sequences that can be used as markers for the genetic analysis of plants. Three approaches were followed for the development of PCR primers for the amplification of DNA fragments containing SSRs from sorghum [Sorghum bicolor (L.) Moench]: a search for sorghum SSRs in public DNA databases; the use of SSR-specific primers developed in the Poaceae species maize (Zea mays L.) and seashore paspalum grass (Paspalum vaginatum Swartz); and the screening of sorghum genomic libraries by hybridization with SSR oligonucleotides. A total of 49 sorghum SSR-specific PCR primer pairs (two designed from GenBank SSR-containing sequences and 47 from the sequences of genomic clones) were screened on a panel of 17 sorghum and one maize accession. Ten primer pairs from paspalum and 90 from maize were also screened for polymorphism in sorghum. Length polymorphisms among amplification products were detected with 15 of these primer pairs, yielding diversity values ranging from 0.2 to 0.8 with an average diversity of 0.56. These primer pairs are now available for use as markers in crop improvement and conservation efforts.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 93 (1996), S. 222-227 
    ISSN: 1432-2242
    Keywords: Malus x domestica ; Anthocyanin biosynthesis ; Marker-assisted selection ; Sequence-tagged site
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A simple genetic basis for the red/yellow skincolor polymorphism in apple was verified using DNA markers. Bulked segregant analysis identified one 10-base oligomer that generated different fragments in each of the bulks. After testing the primer in four populations, two fragments were found to be associated with red skin color and another two fragments associated with yellow skin color. Three of the fragments (1160, 1180, and 1230 bp) were partly sequenced and found to share high sequence homology, suggesting these were generated from the same locus. A pair of universal primers were designed to amplify the fragments. In the ‘Rome Beauty’ x ‘White Angel’ population, two fragments were associated with red skin color; one fragment designated as A1 (1160 bp) was from ‘Rome Beauty’ and another fragment (A2, 1180 bp) was from ‘White Angel’. Progeny possessing both fragments, or either one, had red fruit. Both parents displayed an alternate fragment, a1 (1230 bp), associated with yellowskinned fruit. In three other crosses tested, only fragment A1 co-segregated with red skin color; two fragments, a1 and a2 (1230 bp and 1320 bp), were associated with yellow skin color. Our results are consistent with the hypothesis that the red/yellow dimorphism is controlled by a monogenic system with the presence of the red anthocyanin pigmentation being dominant. There was no indication that other modifier genes could reverse the effect of the locus (R f ) linked to the markers. Examination of amplification products in 56 apple cultivars and advanced breeding selections demonstrated that the universal primers could be used to correctly predict fruit skin color in most cases.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 121 (1994), S. 373-380 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Feeding, growth and bioluminescence of the thecate heterotrophic dinoflagellate Protoperidinium huberi were measured as a function of food concentration for laboratory cultures grown on the diatom Ditylum brightwellii. Ingestion of food increased with food concentration. Maximum ingestion rates were measured at food concentrations of ∼600 μg C l-1 and were ∼0.7 μg C individual-1 h-1 (1.8 D. brightwelli cells individual-1 h-1). Clearance rates decreased asymptotically with increasing food concentration. Maximum clearance rates at low food concentration were ca. 23 μl ind-1 h-1, which corresponds to a volume-specific clearance rate of 5.9x105 h-1. Cell size of P huberi was highly variable, with a mean diameter of 42 μm, but no clear relationship between cell size and food concentration was evident. Specific growth rates increased with food concentration until maximum growth rates of ∼0.7 d-1 were reached at a food concentration of 400 μg C l-1 (∼1000 cells ml-1). Food concentrations as low as 10 μg C l-1 of D. brightwellii (∼25 cells ml-1) were able to support growth of P. huberi. The bioluminescence of P. huberi varied with its nutritional condition and growth rate. Cells held without food lost their bioluminescence capacity in a matter of days. P. huberi raised at different food concentrations showed increased bioluminescence capacity, up to food concentration that supported maximum growth rates. The bioluminescence of P. huberi varied over a diel cycle, and these rhythmic changes persisted during 48 h of continuous darkness, indicating that the rhythm was under endogenous control.
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  • 9
    ISSN: 1432-2242
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Integral equations and operator theory 11 (1988), S. 49-63 
    ISSN: 1420-8989
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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