Phenotypic and genetic charatcterization of a hybrid aspen (Populus × canescens)

The value of wood is based not only on the species from which it was derived, but also on its aesthetic qualities. Figure, which can be defined as any design, pattern, or marking on the longitudinal surfaces of wood, is one of the characteristics that enhances the beauty of wood. In the research reported here, an attempt was made to elucidate the mechanism by which figure is produced by a male hybrid aspen, ‘Curly Poplar’ (P. × canescens), which is also known as ‘Curly Aspen’ or ‘Grober’. To determine whether figure was reproducible, wood produced by rooted propagules of ‘Curly Poplar’ was compared with that of various straight-grained aspens: ‘A502’ (P. alba), ‘4877’ (P. alba), ‘Ca-2-75’ (P. × canescens ), ‘Crandon’ (P. alba × P. grandidentata ), and ‘Sherrill’ (P. alba × P. grandidentata ). More than 80 ‘Curly Poplar’ propagules were sampled at various times (seven, 11, 12, and 60 months) after being grown under two environmental regimes (field vs. greenhouse) and following two treatments (pruned and unpruned). All ‘Curly Poplar’ propagules exhibited figure, represented by an undulating pattern on radial surfaces, which was visible after splitting stems through their pith. No figure was seen in any of the other groups, whose radial surfaces were all smooth and straight. Moreover, the veneer sliced from a 26-year-old ‘Curly Poplar’ tree revealed a type of figure that had not yet been described; thus, it was named ‘Scattered Moiré’. To investigate the mechanism of figure formation, thin sections from 51 vegetative propagules of three genotypes–‘Curly Poplar’, ‘4877’, and ‘Ca-2-75’–grown under greenhouse and field conditions, were used to make permanent microscope slides. In addition to a variety of anatomical measurements, basic specific gravity (BSG), volumetric shrinkage (VS), and field-grown-tree height (TH) were also determined. Our results showed that environmental conditions had an effect on tangential vessel diameter (TVD), fiber length (FL), and vessel length (VL). Ray height in cells (RHC), which is strongly influenced by genetic background, was lower in ‘Curly Poplar’ than in the other genotypes; this property may be associated with figure. Vessel number per mm2 (VMM2) and TVD are unlikely to be related to figure, as they were significantly different only for ‘4877’, regardless of growing conditions. In the greenhouse, ‘Curly Poplar’ had maximal FL and VL. Environmental conditions affected BSG, but not VS. Growth rate in the field was not significant different for any of the aspen genotypes evaluated. Cell-wall sugar composition was also analyzed, but no differences were detected among figured and non-figured trees as shown by an F-test (p\u3e0.05). In an attempt to produce figured wood, the putative orthologs of two Arabidopsis thaliana genes (TUA4 and TUA6 ) were cloned from hybrid poplar clone INRA 353-38 (P. tremula x P. tremuloides) and used to assemble over-expression binary vectors. Dominant negative mutations of those genes have been shown to cause left-handed helical growth and clockwise twisting in elongating organs. Site-directed mutagenesis was used to cause the substitution of serine with phenylalanine at amino acid 180 in proteins encoded by the poplar genes. Constructs that over-expressed mutagenized versions of the poplar genes were transformed in INRA 353-38 via Agrobacterium tumefaciens. Only one transgenic poplar plant exhibited a visual phenotype: shortened internodes in vitro, and twisted petioles in the greenhouse. Quantitative real-time polymerase chain reaction (qRT-PCR) revealed a seven-fold increase in TUA5 expression of this transgenic line, as compared to the wild type, when grown in a greenhouse. The mutagenized poplar TUA3 and TUA7 genes were also over-expressed in Arabidopsis thaliana (Col-0). Only transgenic plants expressing TUA3 showed a phenotype similar to that seen in lefty mutants of A. thaliana. RNA interference constructs were also made using the putative Populus (INRA 353-38) orthologs of the A. thaliana TWD1 gene, and then transformed into INRA 353-38. However, transgenic poplar plants did not show any clear phenotype when compared to wild-type INRA 353-38. (Abstract shortened by UMI.

Figured grain in aspen is heritable and not affected by graft-transmissible signals

Figure can add value to wood products, but its occurrence is unpredictable. A first step in reliably producing figured wood is determining whether it is faithfully transmitted to progeny via sexual and asexual reproduction. We describe a 26-year-old male aspen genotype, designated ‘Curly Poplar’, which was shown to be a Populus × canescens hybrid using microsatellite markers. All rooted cuttings of this genotype exhibited an undulating pattern on the radial surface that was not seen in the control trees, all of which showed a smooth radial surface and straight grain. We observed spiral grain with a magnitude of 2.77 ± 0.12°/cm from vertical in 11-month-old, field-grown rooted Curly Poplar cuttings, but spiral grain was not apparent in wood from the 26-year-old mature ortet that supplied these cuttings. Veneer cut from the mature tree exhibited a novel type of figure that we called ‘Scattered Moiré’. Reciprocal grafts between Curly Poplar and various non-figured aspens showed that a graft-transmissible signals did not appear to be involved in figure formation in Curly Poplar or the induction of figure in straight-grained trees. Curly Poplar was crossed to a straight-grained clone to test the inheritance of the gene(s) responsible for figure. Samples from the resulting population revealed that 79 out of 377 seedlings exhibited figure. A Chi-square test led to the rejection of a 1:1 segregation ratio between figured and non-figured phenotypes (p < 0.01), but not of a 1:3 segregation ratio (p 0.0793). Overall, these analyses showed that figure in Curly Poplar is under genetic control, but its inheritance may not be simple

Optical Coherence Tomography Macular Volume Correlates With Walking Speed in Patients with Multiple Sclerosis (.pdf)

Optical coherence tomography (OCT) is used to measure the thickness of the layers of the retina. In multiple sclerosis (MS), it is used to quantify the effects of optic neuritis or MS, monitor disease progression, and assess for complications of disease modifying therapy. OCT is being evaluated as a potential biomarker in MS, for use in clinics and in therapeutic trials. The aim of this study was to evaluate the relationship between retinal thickness with walking speed in patients with MS/clinically isolated syndrome (CIS)

Multiple Sclerosis Patients With Depression Are More Likely To Subjectively Rate Their Vision Poorly (.pdf)

Depression is a common condition in patients with multiple sclerosis (MS), and is routinely assessed in our MS center using the Patient Health Questionnaire-9 (PHQ-9). Patient-reported outcomes (PRO) are increasingly utilized in clinics and in clinical trials to assess the impact of neurological symptoms on patients' function. The aim of this study was to determine if depression negatively affects a patient's rating of their visual function

Ruthenium-Catalyzed Enantioselective Hydrogenation of 1,8-Naphthyridine Derivatives

The first asymmetric hydrogenation of 2,7-disubstituted 1,8-naphthyridines catalyzed by chiral cationic ruthenium diamine complexes has been developed. A wide range of 1,8-naphthyridine derivatives were effectively hydrogenated to give 1,2,3,4-tetrahydro-1,8-naphthyridines with up to 99% ee and full conversions. The method provides a practical and facile approach to the preparation of valuable chiral heterocyclic building blocks and useful motifs for a new kind of P,N-ligand

Ruthenium-Catalyzed Enantioselective Hydrogenation of 1,8-Naphthyridine Derivatives

The first asymmetric hydrogenation of 2,7-disubstituted 1,8-naphthyridines catalyzed by chiral cationic ruthenium diamine complexes has been developed. A wide range of 1,8-naphthyridine derivatives were effectively hydrogenated to give 1,2,3,4-tetrahydro-1,8-naphthyridines with up to 99% ee and full conversions. The method provides a practical and facile approach to the preparation of valuable chiral heterocyclic building blocks and useful motifs for a new kind of P,N-ligand

Ruthenium-Catalyzed Enantioselective Hydrogenation of 1,8-Naphthyridine Derivatives

The first asymmetric hydrogenation of 2,7-disubstituted 1,8-naphthyridines catalyzed by chiral cationic ruthenium diamine complexes has been developed. A wide range of 1,8-naphthyridine derivatives were effectively hydrogenated to give 1,2,3,4-tetrahydro-1,8-naphthyridines with up to 99% ee and full conversions. The method provides a practical and facile approach to the preparation of valuable chiral heterocyclic building blocks and useful motifs for a new kind of P,N-ligand