Topp, S.H., Rasmussen, S.K., Sander, L.
"Alcohol induced silencing of gibberellin 20-oxidases in Kalanchoe blossfeldiana"
Plant Cell, Tissue and Organ Culture, 93 (3), pp. 241-248. (2008)
Reduction in the amounts of active gibberellic acids (GA) in elongating cuttings from the ornamental crop Kalanchoe blossfeldiana were pursued by genetic manipulation as an alternative to synthetic growth regulators. An alcohol inducible promoter system was used to control silencing of GA activating enzymes. Apart from affecting the stem length, abnormal levels of GA can lead to altered flowering time, lacking seed maturation and changes in morphology. The effects of down regulating a group of GA 20-oxidases were investigated in fast growing cuttings of K. blossfeldiana Poelln. cv. Molly. The transgenic plants were phenotypically indistinguishable from wild type plants until silencing was induced by low concentrations of ethanol. Treated plants were reduced in height but otherwise appeared normal; flowering was delayed but with large variations in time between the transgenic lines. These data indicate that optimisation of the ethanol treatments can enable us to produce more compact growing plants still maintaining normal flowering. © 2008 Springer Science+Business Media B.V.
Lei, T.T., Nilsen, E.T., Semones, S.W.
"Light environment under Rhododendron maximum thickets and estimated carbon gain of regenerating forest tree seedlings"
Plant Ecology, 184 (1), pp. 143-156. (2006)
Canopy tree recruitment is inhibited by evergreen shrubs in many forests. In the southern Appalachian mountains of the USA, thickets of Rhododendron maximum L. restrict dominant canopy tree seedling survival and persistence. Using R. maximum as a model system, we examined available light under the thickets and the photosynthetic responses of seedlings of canopy tree species. We tested the hypothesis that the additional shading from under R. maximum drives carbon gain in seedlings below the threshold for growth and survival. A reduction in light under the thicket was found where canopy openness (derived from canopy photographs) under R. maximum was half the amount measured in forest without R. maximum. R. maximum also reduced direct radiation by 50% and diffuse radiation by 12-29% compared to forest without the shrub layer. Mean mid-day PPFD (photosynthetically active photon flux density between 1000 and 1400 h) under R. maximum (obtained from quantum sensors) was below 10 μmol m -2 s-1 on both clear and overcast days and the amount of sunflecks greater than 10 μmol m-2 s-1 PPFD was only 0-20 min per day. In contrast, forest without R. maximum received a mean PPFD of 18-25 μmol m-2 s-1 on clear days and a cumulative sunfleck duration of 100-220 min per day in all sky conditions. Consistent with light availability between the sites, daily carbon gain in Quercus rubra L. seedlings was lower in forest with R. maximum compared to forest where the shrub was absent. The presence of the shrub layer also significantly suppressed average mid-day photosynthesis of both Q. rubra and Prunus serotina Ehrt. seedlings on 8 out of 11 measurement dates. However, parameters derived from light response curves between seedlings growing in forest sites with or without a thicket of R. maximum was significantly different only in A max (maximum photosynthetic rate), indicating a lack of further acclimation to the deeper shade under R. maximum. While the additional shade cast by R. maximum is sufficient to prevent the regeneration of tree seedlings under this shrub, there was sufficient heterogeneity in light under the thicket to imply that deep shade only partially explains the complete inhibition of regenerating canopy trees under R. maximum. © Springer 2005.
Rathore, N., Knotts IV, T.A., De Pablo, J.J.
"Confinement effects on the thermodynamics of protein folding: Monte Carlo simulations"
Biophysical Journal, 90 (5), pp. 1767-1773. (2006)
The effects of chaperonin-like cage-induced confinement on protein stability have been studied for molecules of varying sizes and topologies. Minimalist models based on Gō-like interactions are employed for the proteins, and density-of-states-based Monte Carlo simulations are performed to accurately characterize the thermodynamic transitions. This method permits efficient sampling of conformational space and yields precise estimates of free energy and entropic changes associated with protein folding. We find that confinement-driven stabilization is not only dependent on protein size and cage radius, but also on the specific topology. The choice of the confining potential is also shown to have an effect on the observed stabilization and the scaling behavior of the stabilization with respect to the cage size. © 2006 by the Biophysical Society.
Woods, K., Hilu, K.W., Wiersema, J.H., Borsch, T.
"Pattern of variation and systematics of Nymphaea odorata: I. Evidence from morphology and inter-simple sequence repeats (ISSRs)"
Systematic Botany, 30 (3), pp. 471-480. (2005)
Nymphaea odorata, Nymphaeaceae, is the most widely distributed water-lily in North America. Disagreement exists on whether this morphologically variable species should be split into two species, N. odorata and N. tuberosa, or treated as one species with two subspecies. Morphological characters and markers from the inter-simple sequence repeats (ISSRs) were examined to assess taxonomic status and elucidate patterns of genetic variation among populations. This study provides evidence against treatment of N. tuberosa at species rank. The principal component analysis of 26 vegetative characters underscores immense variability, but does partially segregate populations of subsp. odorata and subsp. tuberosa. Based on analysis of variance, a new set of morphological characters is proposed to distinguish the two subspecies: mean leaf blade length-to-width ratio, petiole striping, and lobe apex shape. Results from ISSRs show high polymorphism within and among populations. Genetic variation was found largely within geographical regions (89%) rather than among regions. Principal coordinate (PCOA) analyses and minimum spanning tree (MST) analyses based on ISSRs clearly distinguished Nymphaea mexicana and N. odorata. Within N. odorata, samples of subsp. odorata appear to be a distinct entity, whereas samples largely but not completely separated from samples of subsp. tuberosa. PCOA and MST showed linkage between most samples of subsp. odorata whereas this was less evident in UPGMA. © Copyright 2005 by the American Society of Plant Taxonomists.
Jepsen, J.R., Laursen, L.H., Larsen, A.I., Hagert, C.-G.
"Manual strength testing in 14 upper limb muscles: A study of inter-rater reliability"
Acta Orthopaedica Scandinavica, 75 (4), pp. 442-448. (2004)
Background: Manual muscle testing has been termed a "lost art" and is often considered to be of minor value. The aim of this investigation was to study the inter-rater reliability of manual examination of the maximal voluntary strength in a sample of upper limb muscles. Patients and methods: The material consisted of a series of 41 consecutive patients (82 limbs) who had been referred to a clinic of occupational medicine for various reasons. Two examiners who were blinded as to patient-related information classified 14 muscles in terms of normal or reduced strength. In order to optimize the evaluation, the individual strength was assessed simultaneously on the right and left sides with the limbs in standardized positions that were specific for each muscle. Information on upper limb complaints (pain, weakness and/or numbness/tingling) collected by two other examiners resulted in 38 limbs being classified as symptomatic and 44 as asymptomatic. For each muscle the inter-rater reliability of the assessment of strength into normal or reduced was estimated by κ-statistics. In addition, the odds ratio for the relation to symptoms of the definition in agreement of strength was calculated. Results: The median κ-value for strength in the muscles examined was 0.54 (0.25-0.72). With a median odds ratio of 4.0 (2.5-7.7), reduced strength was significantly associated with the presence of symptoms. Interpretation: This study suggests that manual muscle testing in upper limb disorders has diagnostic potential.
Hjelm, M., Bergh, Ø., Riaza, A., Nielsen, J., Melchiorsen, J., Jensen, S., Duncan, H., Ahrens, P., Birkbeck, H., Gram, L.
"Selection and identification of autochthonous potential probiotic bacteria from turbot larvae (Scophthalmus maximus) rearing units"
Systematic and Applied Microbiology, 27 (3), pp. 360-371. (2004)
The purpose of this study was to select, identify and characterise bacteria as a disease control measure in the rearing of marine fish larvae (turbot, Scophthalmus maximus). Thirty-four out of 400 marine bacterial strains exhibited in vitro anti-bacterial activity against three fish larval pathogens. Two strains originated from culture collections and thirty two strains were isolated directly from turbot larvae rearing units using a pre-selection procedure to facilitate detection of antagonists. Approximately 8,500 colonies from colony-count plates were replica-plated on agar seeded with Vibrio anguillarum, and 196 of them caused zones of clearing in the V. anguillarum agar layer. Of these, 32 strains exhibited reproducible antibacterial properties in vitro when tested against the fish pathogens V. anguillarum 90-11-287, V. splendidus DMC-1 and a Pseudoalteromonas HQ. Seventeen antagonists were identified as Vibrio spp. and four of twelve tested were lethal to yolk-sac larvae. The 15 remaining strains were identified as Roseobacter spp. based on phenotypic criteria and 16S rDNA gene sequence analysis of two strains representing the two major RAPD groups. Most of the remaining 164 strains selected in the initial replica plating were identified as Vibrionaceae or Pseudoalteromonas. Roseobacter spp. were not lethal to egg yolk sac turbot larvae and in two of three trials, the mortality of larvae decreased (p > 0.001) in treatments where 107 cfu/ml Roseobacter sp. strain 27-4 was added, indicating a probiotic potential.