Relationship between the earlywood-to-latewood transition and changes in levels of stored starch around the cambium in locally heated stems of the evergreen conifer <Emphasis Type="Italic">Chamaecyparis pisifera</Emphasis>

Key message

We observed the formation of latewood tracheids with narrow diameters and thick walls and the disappearance of stored starch around the cambium on the locally heated region of stems in evergreen conifer Chamaecyparis pisifera during winter cambial dormancy.

Abstract

Wood formation is controlled by cambial cell division, which determines the quantity and quality of wood. We investigated the factors that control cambial activity and the formation of new tracheids in locally heated stems of the evergreen conifer Chamaecyparis pisifera. Electric heating tape was wrapped around one side of the stem, at breast height, of two trees in 2013 and two in 2014. Pairs of stems were locally heated in winter, and small blocks were collected from heated and non-heated regions of stems. Cambial activity and levels of stored starch around the cambium were investigated by microscopy. Cambial reactivation and xylem differentiation occurred earlier in heated than in non-heated regions. New cell plates were formed after 14–18 days of heating. After a few layers of tracheids with large diameters and thin walls had formed, cell division and cell enlargement during differentiation were inhibited. Tracheids with narrow diameters and thick walls, defining those as latewood, were formed near the cambium, and finally, four to six layers of tracheids were induced. After cambial reactivation, amounts of stored starch started to decrease and starch disappeared completely from phloem and xylem cells that were located near the cambium during the differentiation of heated regions. Our results suggest that an increase in temperature induces the conversion of stored starch to soluble sugars for continuous cambial cell division and earlywood formation. By contrast, a shortage of stored starch might be responsible for inhibition of cambial activity and induction of the formation of latewood tracheids.

     

Differentiation of Chlamydia Species by Combined Use of Polymerase Chain Reaction and Restriction Endonuclease Analysis

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Distribution of tobamovirus movement protein in infected cells and implications for cell-to-cell spread of infection

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Effects of a Pulse of Blue Light on the Extracellular pH in the Pulvinus of Phaseolus vulgaris L.: Measurements with a Double-Barreled pH-Sensitive Electrode

Effects of a pulse of blue light on the extracellular pH inthe pulvinus of Phaseolus vulgaris L. were studied with double-barreledpH-sensitive microelectrodes. A blue-light pulse (30 s) inducedtransient alkalization, sometimes with initial acidification.This result is consistent with the hypothesis that blue lightinactivates the plasmalemma H⁺-ATPase. (Received January 17, 1995; Accepted May 29, 1995)     

Antioxidant Activities of Dihydrolipoic Acid and its Structural Homologues

The relationships between structure and antioxidant activity of dihydrolipoic acid (DHLA) were studied using homologues of DHLA: bisonor-DHLA (a derivative which lacks two carbons in the hydrophobic tail), tetranor-DHLA (which lacks four carbons) and a methyl ester derivative. It was observed that: i) DHLA homologues with shorter hydrocarbon tails (i.e., bisnor- and tetranor-DHLA) had greater ability to quench superoxide radicals (O^-₂); ii) no differences among homologues with different chain lengths were found for peroxyl radical (ROO) scavenging in aqueous solution, and iii) DHLA was the best membrane antioxidant in terms of ROO scavening and lipid peroxidation inhibition. Differences among the DHLA homologues in their antioxidant properties in polar and apolar environments generally agreed with differences in their partition coefficients. The methyl ester was the least effective antioxidant both in aqueous phase and in membranes. Tetranor-DHLA was found not only to be less effective in preventing ROO-induced lipid peroxidation, but also to induce lipid peroxidation in the presence of residual iron. Thus, the complexity of biological systems seems to complicate generalizations on the correlation of molecular structure with antioxidant activity of DHLA.     

Formation of Crystalline delta-Endotoxin or Poly-beta-Hydroxybutyric Acid Granules by Asporogenous Mutants of Bacillus thuringiensis

Parental strains and asporogenous mutants of Bacillus thuringiensis subspp. kurstaki and aizawai produced high yields of delta-endotoxin on M medium, which contained 330 mug of potassium per ml, but not on ST and ST-a media, each of which contained only 11 mug of potassium per ml. On ST and ST-a media, refractile granules were formed instead. These granules had no insecticidal activity against silkworms and were isolated and identified as poly-beta-hydroxybutyric acid. Supplementation of the potassium-deficient ST-a medium with 0.1% KH(2)PO(4) (3.7 mM) led to the formation of crystalline delta-endotoxin. The replacement of KH(2)PO(4) with equimolar amounts of KCl, KNO(3), and potassium acetate or an equivalent amount of K(2)SO(4) had a similar effect, whereas the addition of an equimolar amount of NaH(2)PO(4) or NH(4)H(2)PO(4) did not cause the endotoxin to form. An asporogenous mutant, B. thuringiensis subsp. kurstaki strain 290-1, produced delta-endotoxin on ST-a medium supplemented with 3 mM or more potassium but formed only poly-beta-hydroxybutyric acid granules on the media containing 相似文献   

Asporogenous Bacillus thuringiensis Mutant Producing High Yields of delta-Endotoxin

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Distribution and redistribution of pigment granules in the development of sea urchin embryos

Summary Pigment granules (PGs) are embeded in the cortex of embryos of the Japanese sea urchins,Hemicentrotus pulcherrimus and Anthocidaris crassispina. PGs in the cortex actively retreated from the vegetal pole area at the 4-cell stage and then a notable PG-distribution gradient formed along the egg axis (the polar redistribution of PGs). The polar redistribution of PGs in the cortex occurred at the same time after fertilization even in solutions of microtubule disrupting reagents such as Colcemid, vinblastine sulfate or griseofulvin. Consequently, the polar redistribution of PGs was not associated with the microtubules. However, the polar redistribution of PGs was interrupted in seawater containing cytochalasin B (CB), dithiothreitol (DTT) or tetracaine, and the distribution pattern of PGs in the cortex was definitely disturbed. Moreover, CB, DTT and tetracaine altered the division pattern of vegetal blastomeres at the 4th cleavage which is normally unequal so that all the blastomeres divided equally. Microtubule disrupting reagents did not have such an effect on the cleavage pattern. Thus the cortical movement along the egg axis reflected by the polar redistribution of PGs seems to correlate with the micromere formation.     

Application of temperature-sensitive mutants for single-cell protein production

Cell-division-cycle, temperature-sensitive mutants of Saccharomyces cerevisiae were investigated as a means of altering the morphological characteristics and subsequent physical properties of single-cell protein (SCP). Strain 4471, harboring mutation cdc 4, formed a visible complex mass at the nonpermissive temperature, after being grown at 30°C and then transferred to 37°C for 8 hr. Microscopic observation showed that the mother cell was unable to complete the budding process at the nonpermissive temperature, which caused the cells to enlarge. Viscosity measurements were used to establish and characterize optimum morphological changes in the yeast. The Maximum increase in viscosity occurred when cells were incubated at 30°C and then shifted to 37°C for 8 hr. Strain 4471 exhibited yield stress, whereas A364A did not. Maximum change in yield stress occurred when cells were shifted from 30 to 37°C for 8 hr. No significant loss of protein or RNA occurred in strain 4471, as compared to strain A364A, when incubated at the nonpermissive temperature.     

Relative biological efficiency of neutrons (2 MeV) and X-rays for mastocytoma cell division capacity]

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