BACKGROUND: A water-impermeable testa acts as a barrier to a seed's imbibition, thereby imposing dormancy. The physical and functional properties of the macrosclereids are thought to be critical determinants of dormancy; however, the mechanisms underlying the maintenance of and release from dormancy in pea are not well understood. METHODS: Seeds of six pea accessions of contrasting dormancy type were tested for their ability to imbibe and the permeability of their testa was evaluated. Release from dormancy was monitored following temperature oscillation, lipid removal and drying. Histochemical and microscopic approaches were used to characterize the structure of the testa. KEY RESULTS: The strophiole was identified as representing the major site for the entry of water into non-dormant seeds, while water entry into dormant seeds was distributed rather than localized. The major barrier for water uptake in dormant seeds was the upper section of the macrosclereids, referred to as the 'light line'. Dormancy could be released by thermocycling, dehydration or chloroform treatment. Assays based on either periodic acid or ruthenium red were used to visualize penetration through the testa. Lipids were detected within a subcuticular waxy layer in both dormant and non-dormant seeds. The waxy layer and the light line both formed at the same time as the establishment of secondary cell walls at the tip of the macrosclereids. CONCLUSIONS: The light line was identified as the major barrier to water penetration in dormant seeds. Its outer border abuts a waxy subcuticular layer, which is consistent with the suggestion that the light line represents the interface between two distinct environments - the waxy subcuticular layer and the cellulose-rich secondary cell wall. The mechanistic basis of dormancy break includes changes in the testa's lipid layer, along with the mechanical disruption induced by oscillation in temperature and by a decreased moisture content of the embryo.
- MeSH
- hrách setý * MeSH
- klíčení * MeSH
- semena rostlinná MeSH
- teplota MeSH
- vegetační klid MeSH
- voda MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Background and Aims: Root absorptive characteristics rely on the presence of apoplastic barriers. However, little is known about the establishment of these barriers within a complex root system, particularly in a major portion of them - the lateral roots. In Zea mays L., the exodermis differentiates under the influence of growth conditions. Therefore, the species presents a suitable model to elucidate the cross-talk among environmental conditions, branching pattern and the maturation of barriers within a complex root system involved in the definition of the plant-soil interface. The study describes the extent to which lateral roots differentiate apoplastic barriers in response to changeable environmental conditions. Methods: The branching, permeability of the outer cell layers and differentiation of the endo- and exodermis were studied in primary roots and various laterals under different types of stress of agronomic importance (salinity, heavy metal toxicity, hypoxia, etc.). Histochemical methods, image analysis and apoplastic tracer assays were utilized. Key Results: The results show that the impact of growth conditions on the differentiation of both the endodermis and exodermis is modulated according to the type/diameter of the root. Fine laterals clearly represent that portion of a complex root system with a less advanced state of barrier differentiation, but with substantial ability to modify exodermis differentiation in response to environmental conditions. In addition, some degree of autonomy in exodermal establishment of Casparian bands (CBs) vs. suberin lamellae (SLs) was observed, as the absence of lignified exodermal CBs did not always fit with the lack of SLs. Conclusions: This study highlights the importance of lateral roots, and provides a first look into the developmental variations of apoplastic barriers within a complex root system. It emphasizes that branching and differentiation of barriers in fine laterals may substantially modulate the root system-rhizosphere interaction.
Cílem práce bylo srovnat efekt postizometrické relaxace a manuální centrace ramene dle Čápové na utlumení reflexních změn v musculus trapezius při cervikálních bolestivých syndromech. Byla vytvořena skupina pacientů A ošetřovaná postizometrickou relaxací a skupina pacientů B ošetřovaná manuální centrací ramene dle Čápové. Reflexní změny ve svalech byly detekovány diagnostickým režimem kombinované terapie, který využívá měřitelně změněné dráždivosti hypertonních vláken na elektrické podněty oproti normotonním vláknům. Byla zaznamenaná numerická hodnota prahově motorické intenzity před terapií, bezprostředně po terapii a následující den. Práce ukazuje, že obě terapie pracují na rozdílném neurofyziologickém podkladě, ale mají shodný statisticky významný efekt na útlumení reflexních změn ve svalu. Centrace ramene na rozdíl od postizometrické relaxace není cíleně zaměřená na léčbu reflexních změn ve svalu. Snížení hypertonu ve svalu je pouze vedlejší účinek vlastní centrace jako důsledek normalizace koaktivace svalů kolem centrovaného kloubu .
The goal of the thesis was the comparison of the effect of the postisometrical relaxation and manual centration according to Čápová on the trigger points in musculus trapezius when the patient suffers from cervical pain syndromes. The patients were divided into the groups A and B; group A was treated by postisometrical relaxation, and group B by manual centration according to Čápová. The trigger points were detected by the combination therapy. The combination therapy uses the different irritation of hypertonic fibers by electrical stimulus. The numeric value of the treshold motoric intensity was taken down before the therapy, after the therapy and the next day. The thesis shows that both therapies work on a different neurofysiological basis but they have the same statistically significant effect on removing the trigger points in the muscles. The intent of the centration of shoulder is not treating the trigger points in the muscle; this is the focus of the postisometric relaxation. The removal of the trigger points is only a side effect of the centration, due to coactivation of muscles round the centration joint.
