Search

Changes in cellulose content and the accumulation of PpCesA1 mRNA, putatively encoding the catalytic subunit of cellulose synthase (CesA), were analysed in endocarp and mesocarp during endocarp hardening in peach fruit. The cellulose content of the endocarp was undetectable or very low [< 0.1 mg g-1 fresh weight (FW) of endocarp] until 48 d after full bloom (DAFB), but began to increase rapidly at 55 DAFB, when the endocarp had attained its maximum size, and reached 4.4 mg g-1 FW of endocarp at 85 DAFB. In contrast, the cellulose content of the mesocarp reached a detectable level (1.5 mg g-1 FW of mesocarp) at 34 DAFB, stayed at this level until 85 DAFB, but then was lower at 107 DAFB. PpCesA1 mRNA was detected in the endocarp throughout the hardening, but was undetectable in the mesocarp. It is suggested that PpCesA1 has a role in the rapid synthesis of cellulose in the secondary cell walls of endocarp tissue during hardening. [ABSTRACT FROM AUTHOR]

We investigated the effects of reorienting shoots 60° from the vertical to horizontal on carbohydrate concentrations and the related enzyme activities in the lateral bud and the shoot internode of 'Kosui' Japanese pear, to clarify the change of sugar metabolism in response to shoot reorientation which is known to accelerate flower-bud formation. The carbohydrates included: fructose, glucose, sorbitol, sucrose and starch, where the related enzymes included: NAD-dependent sorbitol dehydrogenase (NAD-SDH), NADP-dependent SDH (NADP-SDH), sorbitol oxidase (SOX), sucrose synthase (SS) and acid invertase (AI). Concentrations of sorbitol and sucrose in the lateral buds of a horizontal shoot temporarily decreased on 3 d after shoot reorientation (DAR) but did not differ significantly from those of the controls on 7 DAR and thereafter. On the other hand, sorbitol and sucrose concentrations of the central internode of horizontal shoots were higher on 30 DAR than those of untreated shoots. Glucose and fructose levels were not influenced by shoot reorientation. Activities of NAD-SDH, NADP-SDH and soluble AI, that degrade translocated sugars, in lateral buds increased on 20 and 30 DAR, whereas NAD-SDH in the internode of the shoot center decreased on 30 DAR. No other enzymes measured were influenced by the reorientation. Consequently, these changes may increase the sink capacity of the bud relative to shoot tissue, thereby stimulating bud growth. [ABSTRACT FROM AUTHOR]

We have prepared a series of single quantum wells consisting of a (Ga,Mn)As well and have studied the photo-induced magnetization rotation by means of the time-resolved Kerr rotation measurements with circularly polarized light. In the magnetic circular dichroism spectra, the characteristic broad structure around the band gap energy shifts towards to higher energies with decreasing well layer thickness, indicating the formation of quantized states in a magnetic well. Temporal profile of polar Kerr rotation for the 5-nm quantum wells (QW) (TC=80 K) reveals magnetization rotation from in-plane to out-of-plane direction without the external magnetic fields, with the magnitude of rotation being about 40 times larger than that reported in the bulk. The observed enhancement is discussed in terms of enhanced polarization of hole spins which results from non-degenerate light and heavy hole bands in the QWs. [Copyright &y& Elsevier]