Effects of Inhibitory Concentrations of 3-Indolylacetic Acid and 3-Indolylacetonitrile on Cell Division and Tissue 2

Inhibitory concentrations of 3-indolylacetonitrile (IAN) cause,in cultured excised tomato roots, a marked decrease in the rateof cell division at the apical meristem but only a slight reductionin the lengths of mature exodermal and cortical cells. The reducedrate of cell division is associated with a decrease in the.number of meristematic cells at the root apex. By contrast,3-indolylacetic acid (IAA) causes marked reduction in the lengthsof mature cortical cells but does not markedly reduce cell-divisionrate at the apical meristem. Various lines of evidence indicate that both IAA and IAN causea relative increase in the number of longitudinal and a decreasein the number of transverse division walls in the meristematiczone of the root apex. Partial inhibition of the linear growth of excised tomato rootsby IAA and IAN is accompanied by increases in root and stelardiameters. These increases result from radial enlargement ofthe cortical cells and increase in the number of stelar cellsin the transverse section. The enlarged steles contain an increasednumber of lignified xylem elements, but only with the most inhibitoryconcentration of IAN (10^–4g./ml.) is there evidence ofthe development of secondary xylem. Both auxins increase significantlythe xylem vessel unit length.     

The Role of Calcium Ions in the Acceleration of Resting Muscle Glycolysis by Extracellular Potassium

The activation of the glycolysis of resting muscle by increased extracellular potassium is dependent upon the simultaneous presence of calcium, but not of sodium ions. This regulation of metabolism by a membrane characteristic seems to act upon an early link in the glycolytic enzyme chain.     

Ein Beitrag zur Bekämpfung der Fritfliege in der Roggenzüchtung

Ohne ZusammenfassungMit 2 Abbildungen     

Der Einfluss elektrophysiologisch wirksamer Substanzen auf das mikroskopische Bild des überlebenden Ranvierschen Schnürrings

Cell and Tissue Research - In Ergänzung vorangehender morphologischer Untersuchungen wurde festgestellt, daß nicht nur anisosmotische Lösungen, sondern auch andere, auf die...