Search

The key to using planted Eucalyptus as timber lies in controlling the characteristic high tensile growth stress that often causes serious processing defects in sawn logs and lumber. In the present study, we investigated variations in the longitudinal released strain (RS) of surface growth stress in stems of Eucalyptus grandis W. Hill ex Maiden planted in a wide range of latitudes in Brazil and established relationships between RS measurements and anatomical and chemical factors. Cellulose and lignin content, RS, and the microfibril angle (MFA) of the middle layer of the secondary wall (S2 layer) differed among latitudes. The increase in cellulose content and decrease in MFA were correlated with the contractive value of RS, which explained the higher tensile growth stress in stems from high-latitude plantations where higher cellulose content and lower MFA were observed. To reduce processing defects due to tensile growth stress, the factors controlling MFA values and cellulose content must be identified. Resume: Pour utiliser l'eucalyptus comme bois d'oeuvre, la cle consiste a maitriser les fortes contraintes de tension caracteristiques liees a la croissance et qui causent souvent de graves defauts lors de la transformation des billes et du bois scies. Dans cette etude, nous avons examine la variation des deformations longitudinales (DL) dues au relachement des contraintes de croissance en surface dans le tronc d'Eucalyptus grandis W. Hill ex Maiden plante sous un vaste eventail de latitudes au Bresil et nous avons etabli des relations entre les mesures des DL et les facteurs anatomiques et chimiques. La teneur en cellulose et en lignine, la valeur des DL et l'angle des microfibrilles (AMF) de la paroi [S.sub.2] variaient selon la latitude. L'augmentation de la teneur en cellulose et la diminution de l'AMF etaient correlees avec la valeur contractile des DL, ce qui explique que les contraintes de tension liees a la croissance sont plus importantes dans les tiges provenant de plantations dont la latitude est plus elevee, ou une teneur en cellulose plus elevee et un AMF plus faible ont ete observes. Pour reduire les defauts dus a la transformation, il faut identifier les facteurs qui determinent l'AMF et la teneur en cellulose. [Traduit par la Redaction], Introduction Planting fast-growing Eucalyptus species is expected to rapidly recover deteriorated forestland while supplying the market with a large amount of alternative resources (Cossalter and Pye-Smith 2003). Economic incentive is [...]

Escherichia coli cytosolic glycerophosphodiester phosphodiesterase, UgpQ, functions in the absence of other proteins encoded by the ugp operon and requires [Mg.sup.2+], [Mn.sup.2+], or [Co.sup.2+], in contrast to [Ca.sup.2+]-dependent periplasmic glycerophosphodiester phosphodiesterase, GlpQ. UgpQ has broad substrate specificity toward various glycerophosphodiesters, producing sn-glycerol-3-phosphate and the corresponding alcohols. UgpQ accumulates under conditions of phosphate starvation, suggesting that it allows the utilization of glycerophos-phodiesters as a source of phosphate. These results clarify how E. coli utilizes glycerophosphodiesters using two homologous enzymes, UgpQ and GlpQ.

Escherichia coli cytosolic glycerophosphodiester phosphodiesterase, UgpQ, functions in the absence of other proteins encoded by the ugp operon and requires Mg2+, Mn2+, or Co2+, in contrast to Ca2+-dependent periplasmic glycerophosphodiester phosphodiesterase, GlpQ. UgpQ has broad substrate specificity toward various glycerophosphodiesters, producing sn-glycerol-3-phosphate and the corresponding alcohols. UgpQ accumulates under conditions of phosphate starvation, suggesting that it allows the utilization of glycerophosphodiesters as a source of phosphate. These results clarify how E. coli utilizes glycerophosphodiesters using two homologous enzymes, UgpQ and GlpQ. [ABSTRACT FROM AUTHOR]

We screened cDNA fragments that change their expression during compression wood formation by fluorescent differential display (FDD) in five adult trees (Chamaecyparis obtusa (Siebold & Zucc.) Endl.) growing naturally at an angle to the vertical, and in two saplings, one vertical, the other inclined. We conducted anatomical observations and measurements of the released strain of growth stress on the five adult trees to confirm that they formed compression wood on the lower side of the inclined trunks. Based on sequencing results from selected cDNA fragments, we conducted homology searches of the GenBank database and designed specific primers for the 67 screened fragments. Using these primers and different saplings from those used for the FDD screening, we tested the expression levels of each fragment in normal, compression and opposite wood regions of saplings by semiquantitative reverse-transcription polymerase chain reaction. Twenty-four fragments showed reproducible expression patterns, indicating that these fragments changed their expression during compression wood formation. Some fragments showed differential expression between the apical and basal regions of the lower side of the inclined stem in the region of compression wood formation. Anatomical observations indicated more intense compression wood formation in the basal region than in the apical region of the stem, demonstrating a relationship between compression wood development and gene expression.