DETERMINATION OF HIT NUMBERS FROM DOSE-RESPONSE CURVES FOR PHYTOCHROME CONTROL OF SEED GERMINATION (LACTUCA SATIVA CV NORAN)

1976 ◽  
Vol 25 (5) ◽  
pp. 341-348 ◽  
Author(s):  
O. H. Blaauw ◽  
G. Blaauw-Jansen ◽  
O. Elgersma
Keyword(s):  
Seed Germination ◽  
Dose Response ◽  
Lactuca Sativa ◽  
Response Curves ◽  
Dose Response Curves

Inductively Coupled Electrical Stimulation - Part 4: Effect of PEMF on seed germination; evidence of triphasic inverse hormesis

2021 ◽  
Vol 2 (4) ◽  
pp. 1-44
Author(s):  
Robert Dennis ◽  
Anna Tommerdahl ◽  
Andromeda Dennis
Keyword(s):  
Seed Germination ◽  
Pulse Rate ◽  
Dose Response ◽  
Germination Rate ◽  
Bell Pepper ◽  
Response Curves ◽  
Data Set ◽  
Positive Effects ◽  
Lettuce Seeds ◽  
Dose Response Curves

Our objectives were to study the effects of PEMF on a non-animal living system with a simple and unambiguous biomarker: seed germination rate. We selected seeds representing three groups: high- intermediate- and low-germination-rate seeds (lettuce, bell pepper, and strawberry, respectively). PEMF was applied at 15 pulses per second (pps or Hz) to strawberry and lettuce seeds, and 3 or 15 pps to bell pepper seeds, using only one well-defined PEMF pulse waveform shape and intensity. The only PEMF variables between groups were therefore PEMF pulse rate and total number of pulses, which was taken to be the PEMF dose, equivalent to the duration of exposure at a known pulse rate. In the case of lettuce, we studied the effects of germination using only one PEMF dose compared to no-dose (PEMF -) controls, and no interactions with other pre-planting procedures. In the case of strawberry seeds, we studied possible interactions between PEMF, pre-freezing and pre-soaking of seeds immediately before planting. For bell peppers, extensive dose-response curves are reported. Total dose was calculated as D = R * t, where R = pulse rate (pulses per second) and t = treatment duration (seconds), the product yielding D (dose, i.e. total number of pulses in the PEMF treatment). Bell pepper seeds have an intermediate germination rate that allows the possibility for large and commercially important swings in germination rate both up and down, so we attempted to construct a full spectrum dose-response curve, beginning with PEMF dosing thought to be below threshold then extending into what was thought to potentially be the excessive and toxic range. We also attempted to identify which PEMF parameters are most relevant for dosing: total number of pulses versus “frequency” (pulse rate) and duration of exposure. Results: Lettuce seeds showed evidence of a positive effect of PEMF on germination rate (79% unstimulated, 92% stimulated), with no effect on average time to germination. Strawberry seeds showed little effect of PEMF on germination, if any, and no apparent interaction with pre-freezing or pre-soaking of seeds. Bell Pepper seeds showed a clear inverse hormesis response within the dose range studied, and suggested a tri-phasic response to PEMF exposure for doses in excess of those applied. Specifically, extremely low PEMF doses had a negative effect on bell pepper seed germination rate, whereas intermediate doses had significant positive effects on germination rate, and germination rate began trending down again for the highest PEMF doses, suggesting a third phase of inhibited germination for extreme PEMF dosages. This latter trend was not fully elucidated by the present data set, but is only suggested by data points at the most extreme upper dosages included in this study. Overall, these results were entirely unexpected and may be of importance, therefore independent replication of these results is advised. To explain the unexpected results, a detailed discussion of various multi-phasic dose-response curves is also included. All negative findings were included in this report, specifically to counteract the dominant practice of publication bias in the life sciences.

Increased contractility in vascular smooth muscle of dystrophic hamsters

1983 ◽  
Vol 61 (2) ◽  
pp. 182-185 ◽  
Author(s):  
E. G. Hunter ◽  
J. Elbrink
Keyword(s):  
Animal Model ◽  
Smooth Muscle ◽  
Muscular Dystrophy ◽  
Vascular Smooth Muscle ◽  
Cumulative Dose ◽  
Dose Response ◽  
Response Curves ◽  
Collagen Protein ◽  
Dose Response Curves

To investigate the "vascular" hypothesis of muscular dystrophy, the sensitivity and contractility of aortic spiral strips of dystrophic (BIO 14.6) and normal (FIB) hamsters have been determined to various smooth muscle agonists. The results obtained with cumulative dose–response curves show that there is no increase in the sensitivity of the dystrophic compared with the normal aorta to noradrenaline, phenylephrine, isoproterenol, histamine, or 5-hydroxytryptamine. However, there was a significant increase in the force generated by aortic strips of the dystrophic animals to all agonists. Determination of noncollagen and collagen protein showed that there was no difference in the relative proportions of these proteins in the aortas from the two strains. The results show that in this animal model of dystrophy an increased response to vasopressor amines occurs and is in accordance with that expected of the vascular hypothesis.

Ein Wirkungsspektrum der Photomorphogenese unter Hochenergiebedingungen und seine Interpretation auf der Basis des Phytochroms (Hypokotylwachstumshemmung bei Lactuca sativa L.)

1967 ◽  
Vol 22 (11) ◽  
pp. 1172-1175 ◽  
Author(s):  
Karl M. Hartmann
Keyword(s):  
Dose Response ◽  
Lactuca Sativa ◽  
Wave Length ◽  
Action Spectrum ◽  
Ultra Violet ◽  
Response Curves ◽  
Hypocotyl Length ◽  
Lactuca Sativa L ◽  
Long Time ◽  
Dose Response Curves

Control by ligth of hypocotyl lengthening in lettuce seedlings (Lactuca sativa L., cv. Grand Rapids, tip burn resistant strain) has been investigated using high quality monochromatic bands of radiation between 320 and 1100 nm wave length. Continuous irradiation was applied between 54 and 72 hours after sowing. The increase of hypocotyl length during this period was measured. — A set of characteristic dose-response-curves is presented. For the calculation of the action spectrum — relative quantum efficiency (N447nm/Nλ) as a function of wave length — the branches of the dose-response-curves between 60 and 80% increase were used. The action spectrum shows a symmetric peak around λ = 716 nm with a band width of 30 nm. This fact agrees with the conclusion1 that the far-red peak of action in the case of long-time irradiation is exclusively due to phytochrome. The photostationary state [Pfr] / [P] for optimum effectiveness with respect to control of hypocotyl lengthening in lettuce is probably around 3%. — The fine structure of the action spectrum in the blue and ultraviolet range (especially the peak around λ= 363 nm) points to a flavoproteid as the photoreceptor. On the other hand it is well known 1 that with long-time irradiation short wavelengths light as well will maintain photostationary states of the phytochrome system. Further experiments are required to solve the problem of how much of the effect of blue and ultra-violet light can be attributed to phytochrome.

Observational Determination of Dose-Response Curves in Hallucinogen-Treated Monkeys

1976 ◽  
Vol 11 (2) ◽  
pp. 102-108 ◽  
Author(s):  
J.M. Brewster ◽  
R.K. Siegel ◽  
C.A. Johnson ◽  
M.E. Jarvik
Keyword(s):  
Dose Response ◽  
Response Curves ◽  
Dose Response Curves

Dose-response Curves in the Fibrin Plate Assay Fibrinolytic Activity of Proteases

1974 ◽  
Vol 32 (02/03) ◽  
pp. 356-365 ◽  
Author(s):  
F Haverkate ◽  
D. W Traas
Keyword(s):  
Dose Response ◽  
Fibrinolytic Activity ◽  
Enzyme Concentration ◽  
Response Curves ◽  
Agar Gel ◽  
Porcine Tissue ◽  
Plate Assay ◽  
Fibrin Plate ◽  
Different Types ◽  
Dose Response Curves

SummaryIn the fibrin plate assay different types of relationships between the dose of applied proteolytic enzyme and the response have been previously reported. This study was undertaken to determine whether a generally valid relationship might exist.Trypsin, chymotrypsin, papain, the plasminogen activator urokinase and all of the microbial proteases investigated, including brinase gave a linear relationship between the logarithm of the enzyme concentration and the diameter of the circular lysed zone. A similar linearity of dose-response curves has frequently been found by investigators who used enzyme plate assays with substrates different from fibrin incorporated in an agar gel. Consequently, it seems that this linearity of dose-response curves is generally valid for the fibrin plate assay as well as for other enzyme plate bioassays.Both human plasmin and porcine tissue activator of plasminogen showed deviations from linearity of semi-logarithmic dose-response curves in the fibrin plate assay.

BIOASSAY OF THYROID HORMONE USING HYPOTHYROID TADPOLES

1962 ◽  
Vol 41 (1) ◽  
pp. 143-153 ◽  
Author(s):  
U. Henriques
Keyword(s):  
Thyroid Hormone ◽  
Dose Response ◽  
Developmental Rate ◽  
Response Curves ◽  
Sodium Salts ◽  
Dose Response Curves

ABSTRACT A bioassay of thyroid hormone has been developed using Xenopus larvae made hypothyroid by the administration of thiourea. Only tadpoles of uniform developmental rate were used. Thiourea was given just before the metamorphotic climax in concentrations that produced neoteni in an early metamorphotic stage. During maintained thiourea neotoni, 1-thyroxine and 1-triiodothyronine were added as sodium salts to the water for three days and at the end of one week the stage of metamorphosis produced was determined. In this way identical dose-response curves were obtained for the two compounds. No qualitative differences between their effects were noted except that triiodothyronine seemed more toxic than thyroxine in equivalent doses. Triiodothyronine was found to be 7–12 times as active as thyroxine.

Dose Response Curves for Microwave Ablation in the Cardioplegia-Arrested Porcine Heart

2005 ◽  
Vol 8 (4) ◽  
pp. E269-E274 ◽  
Author(s):  
Sydney L. Gaynor ◽  
Gregory D. Byrd ◽  
Michael D. Diodato ◽  
Yosuke Ishii ◽  
Anson M. Lee ◽  
...  
Keyword(s):  
Dose Response ◽  
Microwave Ablation ◽  
Response Curves ◽  
Porcine Heart ◽  
Dose Response Curves
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