The timing of the auxin response was followed in oat and corn coleoptile tissue by a sensitive optical method in which the elongation of about a dozen coleoptile segments was recorded automatically. The response possesses a latent period of about 10 min at 23 degrees C, which is extended by low concentrations of KCN or by reducing the temperature, but is not extended by pretreatments with actin...

Extending the duration of the late reproductive phase in wheat has been proposed as a possible avenue to improve spike fertility. There is a positive correlation between the number of fertile florets and the duration of the stem elongation phase when this phase is varied by extended photoperiod. Photoperiod treatments imposed during the vegetative period also influence the duration of stem elon...

Aluminium is well known to inhibit plant elongation, but the role in this inhibition played by water relations remains unclear. To investigate this, tobacco (Nicotiana tabacum L.) suspension-cultured cells (line SL) was used, treating them with aluminium (50 microM) in a medium containing calcium, sucrose, and MES (pH 5.0). Over an 18 h treatment period, aluminium inhibited the increase in fres...

Although rapid auxin-induced growth of coleoptile sections can persist for at least 18 hours, acid-induced growth lasts for a much shorter period of time. Three theories have been proposed to explain this difference in persistence. To distinguish between these theories, the pH dependence for auxin-induced growth of oat (Avena sativa L.) coleoptiles has been determined early and late in the el...

The pattern and extent of microtubule assembly during spindle elongation has been examined in PtK1 cells by microinjection of biotin-tubulin and immunolocalization of biotin-tubulin-containing microtubules using antibodies to biotin. PtK1 cells were microinjected at 30 degrees C, incubated for various intervals to allow incorporation of biotin-tubulin into microtubules, then lysed, fixed and st...

Inner ear sensory hair cells convert mechanical stimuli into electrical signals. This conversion happens in the exquisitely mechanosensitive hair bundle that protrudes from the cell's apical surface. In mammals, cochlear hair bundles are composed of 50-100 actin-filled stereocilia, which are organized in three rows in a staircase manner. Stereocilia actin filaments are uniformly oriented with t...

A laser diffraction technique has been developed for registering small changes in sarcomere length. The technique is capable of resolving changes as small as 0.2 A in isolated frog skeletal muscle fibers. The small sarcomere lengthening that accompanies the drop in tension in the latent period of contraction was investigated. We suggest this lengthening be named latency elongation (LE). The LE ...

Summa(iry. Hlydroxy-L-proline-induced inhiibition of elongationi of Aven(a coleoptile segments was measuired in water and in indole-3-acetic aci(l. This inhibition was completely reversed by L-proline. Time-sequence experiments revealed that some time had to elapse, or some eloingationi had to occur, prior to the onset of hydroxyproline inhibition. The presence of sucrose supported the rate of ...

Conceptus expansion throughout the uterus of mammalian species with a noninvasive epitheliochorial type of placentation is critical establishing an adequate uterine surface area for nutrient support during gestation. Pig conceptuses undergo a unique rapid morphological transformation to elongate into filamentous threads within 1 h, which provides the uterine surface to support development and m...

PURPOSE To investigate the refractive and biometric changes associated with adult-onset and adult-progression of myopia in an occupational group. METHODS The sample population consisted of 251 clinical microscopists aged 21 to 63 years. Subjects had their refraction and ocular dimensions measured on four occasions during a 2-year period, and a total of 166 subjects (332 eyes) completed the lo...