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Cytokinin-Induced Wall Extensibility in Excised Cotyledons of Radish and Cucumber 1

Thomas, Jerry; Ross, Cleon W.; Chastain, Chris J.; Koomanoff, Nancy; Hendrix, John E.; Van Volkenburgh, Elizabeth
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /07/1981 EN
Relevância na Pesquisa
27.26%
The mechanism of cytokinin-induced cell expansion in cotyledons excised from dark-grown seedlings of radish (Raphanus sativus L.) and cucumber (Cucumus sativus L.) was studied. Cotyledons were incubated in dim light with or without 17 micromolar zeatin for periods up to 3 days. Fresh weights and osmotic potentials were measured daily. Cell wall extensibility properties were measured before and after the growth period. Also, experiments in which radish cotyledons were grown in mannitol solutions of various concentrations were performed. Comparisons of growth rates and increases of tissue osmotic potentials (toward zero) during growth without mannitol indicate that wall extensibility increased during the growth period and that this extensibility was enhanced by zeatin.

Phytochrome Control of Maize Coleoptile Section Elongation: the Role of Cell Wall Extensibility 1

Warner, Timothy J.; Ross, James D.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/1981 EN
Relevância na Pesquisa
27.45%
Maize (Zea mays) coleoptile section cell wall extensibility was found to be stimulated by red light. This stimulation was largely removed by simultaneous or immediately subsequent far-red treatment. Qualitatively similar patterns of response occurred at 0 C and 20 C. Plastic extensibility responded more than elastic extensibility after red light treatment. Red-induced extensibility increases were detectable by 20 minutes after irradiation, and extensibility continued to increase up to at least 1 hour after irradiation. The kinetics of escape from far-red reversibility indicate that the initial events leading to this phenomenon are among the fastest known phytochrome responses.

Roles of Extensibility and Turgor in Gibberellin- and Dark-stimulated Growth 1

Stuart, David A.; Jones, Russell L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1977 EN
Relevância na Pesquisa
27.26%
The elongation response elicited by incubating excised hypocotyl sections of lettuce (Lactuca sativa L.) in light in gibberellin (GA) can be enhanced by the addition of Cl−, Br−, and NO3− salts of K+ and Na+. Sections incubated in light in the absence of GA do not elongate in response to the addition of salts. In contrast, excised hypocotyls incubated in darkness elongate equally in both GA and water, and their elongation can also be enhanced by KCl treatment. Growth stimulation by the salts of K+ and Na+ occurs optimally at 10 mm and the magnitude of the response is proportional to the duration of salt treatment. Although the growth of sections incubated in light in the absence of GA is not enhanced by various salts of K+ and Na+, the concentration of these cations exceeds that in GA-treated sections. In dark-grown tissue, uptake of K+ also occurs in both GA- and H2O-treated sections incubated in 10 mm KCl. Since increased osmotic potential resulting from cation uptake does not correlate with growth stimulation resulting from salt treatments, we conclude that increased cell turgor is not the principal driving force for growth in hypocotyl sections. Changes in the extensibility of GA-treated, light-grown tissue and dark-grown tissue incubated with and without GA correlate with the increased growth rate of these sections. Incubation of sections in KCl results only in changes in water potential of sections without having a significant effect on extensibility. When changes in water potential are accompanied by increased extensibility...

Salinity Stress Inhibits Bean Leaf Expansion by Reducing Turgor, Not Wall Extensibility 1

Neumann, Peter M.; Van Volkenburgh, Elizabeth; Cleland, Robert E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1988 EN
Relevância na Pesquisa
27.45%
Treatment of bean (Phaseolus vulgaris L.) seedlings with low levels of salinity (50 or 100 millimolar NaCl) decreased the rate of light-induced leaf cell expansion in the primary leaves over a 3 day period. This decrease could be due to a reduction in one or both of the primary cellular growth parameters: wall extensibility and cell turgor. Wall extensibility was assessed by the Instron technique. Salinity did not decrease extensibility and caused small increases relative to the controls after 72 hours. On the other hand, 50 millimolar NaCl caused a significant reduction in leaf bulk turgor at 24 hours; adaptive decreases in leaf osmotic potential (osmotic adjustment) were more than compensated by parallel decreases in the xylem tension potential and the leaf apoplastic solute potential, resulting in a decreased leaf water potential. It is concluded that in bean seedlings, mild salinity initially affects leaf growth rate by a decrease in turgor rather than by a reduction in wall extensibility. Moreover, longterm salinization (10 days) resulted in an apparent mechanical adjustment, i.e. an increase in wall extensibility, which may help counteract reductions in turgor and maintain leaf growth rates.

Differential Effect of Auxin on in Vivo Extensibility of Cortical Cylinder and Epidermis in Pea Internodes 1

Kutschera, Ulrich; Briggs, Winslow R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1987 EN
Relevância na Pesquisa
27.37%
The effect of auxin indole-3-acetic acid (IAA) on growth and in vivo extensibility of third internode sections from red light grown pea seedlings (Pisum sativum L. cv Alaska) and the isolated tissues (cortex plus vascular tissue = cortical cylinder, and epidermis) was investigated. Living tissue was stretched at constant force (creep test) in a custom-built extensiometer. In the intact section, IAA-induced increase in total (Etot), elastic (Eel), and plastic (Epl) extensibility is closely related to the growth rate. The extensibility of the cortical cylinder, measured immediately after peeling of intact sections incubated for 4 hours in IAA, is not increased by IAA. Epidermal strips, peeled from growing sections incubated in IAA, show a Epl increase, which is correlated to the growth rate of the intact segments. The isolated cortical cylinder expands in water; IAA has only a small growth-promoting effect. The extensibility of the cortical cylinder is not increased by IAA. Epidermal strips contract about 10% on isolation. When incubated in IAA, they do not elongate, but respond with an Epl increase. The amount of expansion of the cortical cylinder and contraction of the epidermis (tissue tension), measured immediately following excision and peeling...

Gibberellic Acid Regulates Cell Wall Extensibility in Wheat (Triticum aestivum L.) 1

Keyes, Geoff; Sorrells, Mark E.; Setter, Tim L.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1990 EN
Relevância na Pesquisa
27.37%
Mutations (Rht genes) blocking sensitivity to gibberellic acid (GA) were used to examine phytohormone mediated cell wall expansion in wheat (Triticum aestivum L.). Irreversible extensibility of immature leaf segments, as determined by stress/strain (instron) measurements, declined with Rht gene dose. Exogenous GA3 significantly increased wall extensibility in the nonmutant controls but had no effect on the near-isogenic GA-insensitive genotypes. Furthermore, ancymidol, an inhibitor of gibberellin biosynthesis, diminished wall extensibility in the nonmutant control. Extensibility of immature segments was highly correlated with mature leaf sheath length (R = +0.95). The results indicate that wall yielding properties of expanding wheat leaves are associated with leaf cell expansion potential and that GA is involved in the determination of those properties.

Wall Extensibility and Cell Hydraulic Conductivity Decrease in Enlarging Stem Tissues at Low Water Potentials 1

Nonami, Hiroshi; Boyer, John S.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1990 EN
Relevância na Pesquisa
27.26%
Measurements with a guillotine psychrometer (H Nonami, JS Boyer [1990] Plant Physiol 94: 1601-1609) indicate that the inhibition of stem growth at low water potentials (low ψw) is accompanied by decreases in cell wall extensibility and tissue hydraulic conductance to water that eventually limit growth rate in soybean (Glycine max L. Merr.). To check this conclusion, we measured cell wall properties and cell hydraulic conductivities with independent techniques in soybean seedlings grown and treated the same way, i.e. grown in the dark and exposed to low ψw by transplanting dark grown seedlings to vermiculite of low water content. Wall properties were measured with an extensiometer modified for intact plants, and conductances were measured with a cell pressure probe in intact plants. Theory was developed to relate the wall measurements to those with the psychrometer. In the elongation zone, the plastic deformability of the walls decreased when measured with the extensiometer while growth was inhibited at low ψw. It increased during a modest growth recovery. This behavior was the same as that for the wall extensibility observed previously with the psychrometer. Tissue that was killed before measurement with the extensiometer also showed a similar response...

Growth Physics in Nitella: a Method for Continuous in Vivo Analysis of Extensibility Based on a Micro-manometer Technique for Turgor Pressure 1

Green, Paul B.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1968 EN
Relevância na Pesquisa
27.55%
The view that the plant cell grows by the yielding of the cell wall to turgor pressure can be expressed in the equation: rate = cell extensibility × turgor. All growth rate responses can in principle be resolved into changes in the 2 latter variables. Extensibility will relate primarily to the yielding properties of the cell wall, turgor primarily to solute uptake or production. Use of this simple relationship in vivo requires that at least 2 of the 3 variables be measured in a growing cell. Extensibility is not amenable to direct measurement. Data on rate and turgor for single Nitella cells can, however, be continuously gathered to permit calculation of extensibility (rate/turgor). Rate is accurately obtained from measurements on time-lapse film. Turgor is estimated in the same cell, to within 0.1 atm or less, by measurement of the ability of the cell to compress gas trapped in the closed end of a capillary the open end of which is in the cell vacuole. The method is independent of osmotic equilibrium. It operates continuously for several days, over a several fold increase in cell length, and has response time of less than one minute. Rapid changes in turgor brought on by changes in tonicity of the medium, show that extensibility...

Influence of Hamstring Muscles Extensibility on Spinal Curvatures and Pelvic Tilt in Highly Trained Cyclists

Muyor, José M.; Alacid, Fernando; López-Miñarro, Pedro A.
Fonte: Versita, Warsaw Publicador: Versita, Warsaw
Tipo: Artigo de Revista Científica
Publicado em 04/10/2011 EN
Relevância na Pesquisa
27.51%
The purpose of this study was to determine the influence of hamstring muscles extensibility in standing, maximal trunk flexion with knees extended and on the bicycle in lower handlebar-hands position of highly trained cyclists. Ninety-six cyclists were recruited for the study (mean ± SD, age: 30.36 ± 5.98 years). Sagittal spinal curvatures and pelvic tilt were measured in the standing position, maximal trunk flexion with knees extended (sit-and-reach test) and while sitting on a bicycle in lower handlebar-hand position using a Spinal Mouse system. Hamstring muscles extensibility was determined in both legs by passive straight leg raise test (PSLR). The sample was divided into three groups according to PSLR angle: (1) reduced extensibility (PSLR < 80º; n = 30), (2) moderate hamstring extensibility group (PSLR = 80º – 90º; n = 35), and (3) high hamstring extensibility (PSLR = > 90º; n = 31). ANOVA analysis showed significant differences among groups for thoracic (p < 0.001) and pelvic tilt (p < 0.001) angles in the sit-and-reach test. No differences were found between groups for standing and on the bicycle position. Post hoc analysis showed significant differences in all pairwise comparisons for thoracic angle (p < 0.01) and pelvic angle (p < 0.001) in the sit-and-reach test. No differences were found in lumbar angle in any posture. In conclusion...

Criterion-Related Validity of Sit-and-Reach Tests for Estimating Hamstring and Lumbar Extensibility: a Meta-Analysis

Mayorga-Vega, Daniel; Merino-Marban, Rafael; Viciana, Jesús
Fonte: Asist Group Publicador: Asist Group
Tipo: Artigo de Revista Científica
Publicado em 20/01/2014 EN
Relevância na Pesquisa
27.65%
The main purpose of the present meta-analysis was to examine the scientific literature on the criterion-related validity of sit-and-reach tests for estimating hamstring and lumbar extensibility. For this purpose relevant studies were searched from seven electronic databases dated up through December 2012. Primary outcomes of criterion-related validity were Pearson´s zero-order correlation coefficients (r) between sit-and-reach tests and hamstrings and/or lumbar extensibility criterion measures. Then, from the included studies, the Hunter- Schmidt´s psychometric meta-analysis approach was conducted to estimate population criterion- related validity of sit-and-reach tests. Firstly, the corrected correlation mean (rp), unaffected by statistical artefacts (i.e., sampling error and measurement error), was calculated separately for each sit-and-reach test. Subsequently, the three potential moderator variables (sex of participants, age of participants, and level of hamstring extensibility) were examined by a partially hierarchical analysis. Of the 34 studies included in the present meta-analysis, 99 correlations values across eight sit-and-reach tests and 51 across seven sit-and-reach tests were retrieved for hamstring and lumbar extensibility...

Estimation and utilisation of glutenin gene effects from the analysis of unbalanced data from wheat breeding programs

Eagles, H.; Hollamby, G.; Gororo, N.; Eastwood, R.
Fonte: C S I R O Publishing Publicador: C S I R O Publishing
Tipo: Artigo de Revista Científica
Publicado em //2002 EN
Relevância na Pesquisa
27.37%
Glutenins are a major determinant of dough characteristics in wheat. These proteins are determined by genes at 6 loci (Glu genes), with multiple alleles present in most breeding programs. This study was conducted to determine whether estimates of allele effects for the important dough rheological characters, maximum dough resistance (Rmax) and dough extensibility, could be determined from aggregated data from southern Australian wheat breeding programs using statistical techniques appropriate for unbalanced data. From a 2-stage analysis of 3226 samples of 1926 cultivars and breeding lines, estimates of Rmax and extensibility effects were obtained, first for the lines, and then for 31 glutenin alleles. Glutenin genes did not determine flour protein concentration, and this character was used as a covariate. Rankings of the estimates of Rmax for the alleles were similar to the relative scores for dough strength reported from previous studies, providing strong evidence that the analysis of a large, unbalanced data set from applied wheat breeding programs can provide reliable estimates. All 2-way interactions between loci were present for 18 of the alleles. Analyses including interactions showed that epistasis was important for both Rmax and extensibility...

Layer- and Direction-Specific Material Properties, Extreme Extensibility and Ultimate Material Strength of Human Abdominal Aorta and Aneurysm: A Uniaxial Extension Study

Teng, Zhongzhao; Feng, Jiaxuan; Zhang, Yongxue; Huang, Yuan; Sutcliffe, Michael P. F.; Brown, Adam J.; Jing, Zaiping; Gillard, Jonathan H.; Lu, Qingsheng
Fonte: Springer US Publicador: Springer US
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.37%
Mechanical analysis has the potential to provide complementary information to aneurysm morphology in assessing its vulnerability. Reliable calculations require accurate material properties of individual aneurysmal components. Quantification of extreme extensibility and ultimate material strength of the tissue are important if rupture is to be modelled. Tissue pieces from 11 abdomen aortic aneurysm (AAA) from patients scheduled for elective surgery and from 8 normal aortic artery (NAA) from patients who scheduled for kidney/liver transplant were collected at surgery and banked in liquid nitrogen with the use of Cryoprotectant solution to minimize frozen damage. Prior to testing, specimen were thawed and longitudinal and circumferential tissue strips were cut from each piece and adventitia, media and thrombus if presented were isolated for the material test. The incremental Young’s modulus of adventitia of NAA was direction-dependent at low stretch levels, but not the media. Both adventitia and media had a similar extreme extensibility in the circumferential direction, but the adventitia was much stronger. For aneurysmal tissues, no significant differences were found when the incremental moduli of adventitia, media or thrombus in both directions were compared. Adventitia and media from AAA had similar extreme extensibility and ultimate strength in both directions and thrombus was the weakest material. Adventitia and media from AAA were less extensible compared with those of NAA...

Molecular dissection of N2B cardiac titin's extensibility.

Trombitás, K; Freiburg, A; Centner, T; Labeit, S; Granzier, H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1999 EN
Relevância na Pesquisa
27.37%
Titin is a giant filamentous polypeptide of multidomain construction spanning between the Z- and M-lines of the cardiac muscle sarcomere. Extension of the I-band segment of titin gives rise to a force that underlies part of the diastolic force of cardiac muscle. Titin's force arises from its extensible I-band region, which consists of two main segment types: serially linked immunoglobulin-like domains (tandem Ig segments) interrupted with a proline (P)-, glutamate (E)-, valine (V)-, and lysine (K)-rich segment called PEVK segment. In addition to these segments, the extensible region of cardiac titin also contains a unique 572-residue sequence that is part of the cardiac-specific N2B element. In this work, immunoelectron microscopy was used to study the molecular origin of the in vivo extensibility of the I-band region of cardiac titin. The extensibility of the tandem Ig segments, the PEVK segment, and that of the unique N2B sequence were studied, using novel antibodies against Ig domains that flank these segments. Results show that only the tandem Igs extend at sarcomere lengths (SLs) below approximately 2.0 microm, and that, at longer SLs, the PEVK and the unique sequence extend as well. At the longest SLs that may be reached under physiological conditions ( approximately 2.3 microm)...

Growth, in Vivo Extensibility, and Tissue Tension in Developing Pea Internodes 1

Kutschera, Ulrich; Briggs, Winslow R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/1988 EN
Relevância na Pesquisa
27.45%
The relationship between growth, in vivo extensibility, and tissue tension in the first 3 internodes of 5, 6, and 7 day-old pea plants (Pisum sativum L. cv Alaska), grown under continuous red light was investigated. The upper 15 millimeters of each internode was marked with ink and its elongation growth measured over the next subsequent 8 hours. In vivo extensibility was measured by stretching living tissue at constant force (creep test) in a custom-built extensiometer. Tissue tension was determined by (a) measuring the rate of expansion of the isolated cortical cylinder after adding water and the amount of contraction of the epidermis after peeling, and (b) by use of the `split section test.' A good correlation between rate of elongation growth, in vivo extensibility, and tissue tension was established. The epidermis peeled from the growing third internode of 7 day-old plants and measured immediately showed a plastic extensibility (Epl twice that of peels from nongrowing excised sections. This high Epl-value was lost on incubation of the sections in distilled water, and was subsequently restored by incubating the sections in auxin (indole-3-acetic acid). We conclude that the in situ growth of the internodes is a function of tissue-tension...

On the theory of muscle contraction: filament extensibility and the development of isometric force and stiffness.

Mijailovich, S M; Fredberg, J J; Butler, J P
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1996 EN
Relevância na Pesquisa
27.37%
The newly discovered extensibility of actin and myosin filaments challenges the foundation of the theory of muscle mechanics. We have reformulated A. F. Huxley's sliding filament theory to explicitly take into account filament extensibility. During isometric force development, growing cross-bridge tractions transfer loads locally between filaments, causing them to extend and, therefore, to slide locally relative to one another. Even slight filament extensibility implies that 1) relative displacement between the two must be nonuniform along the region of filament overlap, 2) cross-bridge strain must vary systematically along the overlap region, and importantly, 3) the local shortening velocities, even at constant overall sarcomere length, reduce force below the level that would have developed if the filaments had been inextensible. The analysis shows that an extensible filament system with only two states (attached and detached) displays three important characteristics: 1) muscle stiffness leads force during force development; 2) cross-bridge stiffness is significantly higher than previously assessed by inextensible filament models; and 3) stiffness is prominently dissociated from the number of attached cross-bridges during force development. The analysis also implies that the local behavior of one myosin head must depend on the state of neighboring attachment sites. This coupling occurs exclusively through local sliding velocities...

Study on changes in skin extensibility during the development of joint contracture due to joint immobilization in rats

Tasaka, Atsushi; Ono, Takeya; Oki, Sadaaki; Umei, Namiko; Ishikura, Hideki; Aihara, Kazuki; Sato, Yuta; Matsumoto, Tomohiro
Fonte: The Society of Physical Therapy Science Publicador: The Society of Physical Therapy Science
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.37%
[Purpose] The purpose of this study was to elucidate whether skin extensibility decreases when a contracture develops as a result of joint immobilization. [Subjects] This study was conducted on six female Wistar rats. [Methods] The rats were divided into two experimental groups. In the immobilized group, the right ankle joints were immobilized in complete plantar flexion by plaster casts for two weeks. In the control group, the left ankle joints had no intervention. On the final day, skin extensibility was determined from a length-tension curve by collecting skin from the posterior aspect of the ankle joint and using a tensile strength tester. [Results] Compared with the control group, the immobilized group showed a significant decrease in skin extensibility. [Conclusion] The results demonstrated that the extensibility of the skin itself decreases when joint contracture develops.

A uni-extension study on the ultimate material strength and extreme extensibility of atherosclerotic tissue in human carotid plaques

Teng, Zhongzhao; Feng, Jiaxuan; Zhang, Yonhxue; Sutcliffe, Michael P. F.; Huang, Yuan; Brown, Adam J.; Jing, Zaiping; Lu, Qingsheng; Gillard, Jonathan H.
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; published version
EN
Relevância na Pesquisa
37.45%
This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.jbiomech.2015.09.037; Atherosclerotic plaque rupture occurs when mechanical loading exceeds its material strength. Mechanical analysis has been shown to be complementary to the morphology and composition for assessing vulnerability. However, strength and stretch thresholds for mechanics-based assessment are currently lacking. This study aims to quantify the ultimate material strength and extreme extensibility of each atherosclerotic component from human carotid plaques. Tissue strips of fibrous cap, media, lipid core and intraplaque hemorrhage/thrombus were obtained from 21 carotid endarterectomy samples of symptomatic patients. Uni-extension test with tissue strips was performed until they broke or slid. The Cauchy stress and stretch ratio at the peak loading of strips broken about 2 mm away from the clamp were used to characterize their ultimate strength and extensibility. Results obtained indicated that ultimate strength of fibrous cap and media were 158.3 [72.1, 259.3] kPa (Median [Inter quartile range]) and 247.6 [169.0, 419.9] kPa, respectively; those of lipid and intraplaque hemorrhage/thrombus were 68.8 [48.5, 86.6] kPa and 83.0 [52.1...

Layer- and direction-specific material properties, extreme extensibility and ultimate material strength of human abdominal aorta and aneurysm: a uniaxial extension study

Teng, Zhongzhao; Feng, Jiaxuan; Zhang, Yongxue; Huang, Yuan; Sutcliffe, Michael P. F.; Brown, Adam J.; Jing, Zaiping; Gillard, Jonathan H.; Lu, Qingsheng
Fonte: Springer Publicador: Springer
Tipo: Article; published version
EN
Relevância na Pesquisa
37.45%
This is the final version. It was first published by Springer at http://dx.doi.org/10.1007/s10439-015-1323-6; Mechanical analysis has the potential to provide complementary information to aneurysm morphology in assessing its vulnerability. Reliable calculations require accurate material properties of individual aneurysmal components. Quantification of extreme extensibility and ultimate material strength of the tissue are important if rupture is to be modelled. Tissue pieces from 11 abdomen aortic aneurysm (AAA) from patients scheduled for elective surgery and from 8 normal aortic artery (NAA) from patients who scheduled for kidney/liver transplant were collected at surgery and banked in liquid nitrogen with the use of Cryoprotectant solution to minimize frozen damage. Prior to testing, specimen were thawed and longitudinal and circumferential tissue strips were cut from each piece and adventitia, media and thrombus if presented were isolated for the material test. The incremental Young?s modulus of adventitia of NAA was direction-dependent at low stretch levels, but not the media. Both adventitia and media had a similar extreme extensibility in the circumferential direction, but the adventitia was much stronger. For aneurysmal tissues...

Wheat-flour dough extensibility as a discriminator for wheat varieties

Anderssen, Robert S; Bekes, F; Gras, P W; Nikolov, A; Wood, Jeffrey
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
27.37%
The extension testing of wheat-flour dough has become one of the key cereal chemistry links to end product quality assessment, because of its perceived relevance to baking performance, and because of the various correlations that have been inferred and assumed since the extensibility of a dough was first investigated in the late 19th century. As a consequence, from a plant breeding perspective, there is a need to understand and interpret the extensibility of a dough in terms of the molecular dynamics occurring during its extension, not only as it relates to its baking, but also to the HMW/LMW glutenin and gliadin composition of the wheat. The focus of this paper is the direct measurement of extensibility on a micro-extension tester. The theoretical justification is that the resulting extensogram represents an encapsulation of the extensional rheology of the dough. The paper reports on a graphical and statistical analysis of extension tests performed on eight representative flours. They yield validation for the conclusion that the historic assessment of extensibility as ExtRupture should be replaced by ExtRmax and the difference ExtRupture - ExtRmax. It is relatively easy to obtain accurate estimates of R max, ExtRmax and ExtRupture from electronically recorded extensograms. Among other things...

Contribution of Glu-B1, Glu-D1 and Glu-B3 loci to dough quality of bread wheat

Martínez Cruz,Eliel; Espitia Rangel,Eduardo; Villaseñor Mir,Héctor E.; Peña Bautista,Roberto J.
Fonte: Sociedad Mexicana de Fitogenética A.C. Publicador: Sociedad Mexicana de Fitogenética A.C.
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2012 EN
Relevância na Pesquisa
27.45%
The aim of this research was to identify the combinations and allelic variants of high and low molecular weight glutenins (HMWG and LMWG) to determine their effects on the rheological characteristics of dough of bread wheat (Triticum aestivum L.). A set of 98 lines derived by single seed descent from F2 to F6 of the cross 'Bacanora T88 x Salamanca' was used. Genotypes were sown at Celaya, Guanajuato, México, 2008 during the Winter-Spring cycle. Variables evaluated were:mixing time, mixing stability, tolerance to overmixing, dough strength and the tenacity/extensibility ratio. Both HMWG and LMWG were identified with sodium dodecyl sulfate in polyacrylamide gel. It was found that loci Glu-B1, Glu-D1 and Glu-B3 affected both dough strength and extensibility. The combination 2*, 7+9, 5 +10, c, g, b was associated to strong gluten and excellent extensibility, suitable for bread-making; in contrast, combination 2*, 7+9, 2+12, c, g, b showed weak and extensible gluten, useful for manufacturing cookies and tortillas. The combination 2*, 7+9, 2+12 c, j, b showed lowest dough strength and 2*, 7+8, 2+12 c, j, b showed the highest extensibility. Alleles 7+9 and 5+10 were associated with higher gluten strength than alleles 7+8 and 2+12. The highest tenacity and lowest ratio tenacity/extensibility values were presented by the allele j...