GLORIA — GEOMAR Library Ocean Research Information Access

Hits per page

hits 1 - 2 | 2 hits

Sorting

Electronic Resource

Computer-based video digitizer analysis of surface extension in maize roots (1991)

Ishikawa, Hideo ; Hasenstein, Karl H. ; Evans, Michael L.

Springer

Planta 183 (1991), S. 381-390

add to mindlist on the mindlist

Details

ISSN: 1432-2048

Keywords: Digitizer ; Gravitropism (root, digitizer analysis) ; Growth (root) ; Root (gravitropism, growth) ; Zea (root gravitropism)

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract We used a video digitizer system to measure surface extension and curvature in gravistimulated primary roots of maize (Zea mays L.). Downward curvature began about 25 ± 7 min after gravistimulation and resulted from a combination of enhanced growth along the upper surface and reduced growth along the lower surface relative to growth in vertically oriented controls. The roots curved at a rate of 1.4 ± 0.5° · min−1 but the pattern of curvature varied somewhat. In about 35% of the samples the roots curved steadily downward and the rate of curvature slowed as the root neared 90°. A final angle of about 90° was reached 110 ±35 min after the start of gravistimulation. In about 65% of the samples there was a period of backward curvature (partial reversal of curvature) during the response. In some cases (about 15% of those showing a period of reverse bending) this period of backward curvature occurred before the root reached 90°. Following transient backward curvature, downward curvature resumed and the root approached a final angle of about 90°. In about 65% of the roots showing a period of reverse curvature, the roots curved steadily past the vertical, reaching maximum curvature about 205 ± 65 min after gravistimulation. The direction of curvature then reversed back toward the vertical. After one or two oscillations about the vertical the roots obtained a vertical orientation and the distribution of growth within the root tip became the same as that prior to gravistimulation. The period of transient backward curvature coincided with and was evidently caused by enhancement of growth along the concave and inhibition of growth along the convex side of the curve, a pattern opposite to that prevailing in the earlier stages of downward curvature. There were periods during the gravitropic response when the normally unimodal growth-rate distribution within the elongation zone became bimodal with two peaks of rapid elongation separated by a region of reduced elongation rate. This occurred at different times on the convex and concave sides of the graviresponding root. During the period of steady downward curvature the elongation zone along the convex side extended farther toward the tip than in the vertical control. During the period of reduced rate of curvature, the zone of elongation extended farther toward the tip along the concave side of the root. The data show that the gravitropic response pattern varies with time and involves changes in localized elongation rates as well as changes in the length and position of the elongation zone. Models of root gravitropic curvature based on simple unimodal inhibition of growth along the lower side cannot account for these complex growth patterns.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00197737

Permalink

	Location	Call Number	Limitation	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

Electronic Resource

Determination of the primary structure of peptides using fast atom bombardment mass spectrometry (1990)

Zidarov, Dimo ; Thibault, Pierre ; Evans, Michael J. ; [et al.]

Chichester : Wiley-Blackwell

Biological Mass Spectrometry 19 (1990), S. 13-26

add to mindlist on the mindlist

Details

ISSN: 1052-9306

Keywords: Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The determination of the amino acid composition and sequence of a peptide, using both conventional and tandem fast atom bombardment mass spectrometry, is presented. First a list of potential empirical formulae is generated using the accurate mass and isotopic peak intensity ratios from the molecular ion cluster. The formulae are mathematically analyzed to ensure that they correspond to linear peptides composed of 19 common amino acids. Then using the ions below m/z 160 Da, which are characteristic of the amino acid content of the peptide, the formulae are decomposed into possible amino acid compositions. From each composition sequences are generated and their predicted fragment ions are compared to ions present in the mass spectrum. A score based on the intensities and the occurrence of consecutive sequence fragments is calculated. Finally sequences with the ten highest scores are retained. Analyses performed on typical peptides with molecular weights below 1500 Da indicate that identification can generally be achieved using this approach.

Additional Material: 5 Ill.