ABSTRACT
Two main strategies allow plants to deal with submergence: (i) escape from below water by means of shoot elongation, or (ii) remaining quiescent under the water until water subsides and then resume growth. We investigated these strategies in seedlings of Lotus japonicus, L. corniculatus and L. tenuis subjected to control and submergence for 12 days, with a subsequent 30-day recovery period. All three species survived submergence but used different strategies. Submerged seedlings of L. japonicus exhibited an escape strategy (emerging from water) as a result of preferential carbon allocation towards shoot mass and lengthening, in detriment to root growth. In contrast, seedlings of L. corniculatus and L. tenuis became quiescent, with no biomass accumulation, no new unfolding of leaves and no shoot elongation. Upon de-submergence, seedlings of L. japonicus had the lowest recovery growth (a biomass and shoot height 58% and 40% less than controls, respectively), L. corniculatus was intermediate and L. tenuis showed the greatest recovery growth. Previously submerged seedlings of L. tenuis did not differ from their controls, either in final shoot biomass or shoot height. Thus, for the studied species, quiescence appears to be an adequate strategy for tolerance of short-term (i.e., 12 days) complete submergence, being consistent with field observations of L. tenuis colonisation of flood-prone environments.
Subject(s)
Floods , Lotus/growth & development , Water/physiology , Plant Leaves/growth & development , Plant Roots/growth & development , Plant Shoots/growth & development , Seedlings/growth & developmentABSTRACT
BACKGROUND AND AIMS: Two main strategies that allow plants to cope with soil waterlogging or deeper submergence are: (1) escaping by means of upward shoot elongation or (2) remaining quiescent underwater. This study investigates these strategies in Lotus tenuis, a forage legume of increasing importance in areas prone to soil waterlogging, shallow submergence or complete submergence. METHODS: Plants of L. tenuis were subjected for 30 d to well-drained (control), waterlogged (water-saturated soil), partially submerged (6 cm water depth) and completely submerged conditions. Plant responses assessed were tissue porosity, shoot number and length, biomass and utilization of water-soluble carbohydrates (WSCs) and starch in the crown. KEY RESULTS: Lotus tenuis adjusted its strategy depending on the depth of submergence. Root growth of partially submerged plants ceased and carbon allocation prioritized shoot lengthening (32 cm vs. 24.5 cm under other treatments), without depleting carbohydrate reserves to sustain the faster growth. These plants also developed more shoot and root porosity. In contrast, completely submerged plants became quiescent, with no associated biomass accumulation, new shoot production or shoot elongation. In addition, tissue porosity was not enhanced. The survival of completely submerged plants is attributed to consumption of WSCs and starch reserves from crowns (concentrations 50-75 % less than in other treatments). CONCLUSIONS: The forage legume L. tenuis has the flexibility either to escape from partial submergence by elongating its shoot more vigorously to avoid becoming totally submerged or to adopt a non-elongating quiescent strategy when completely immersed that is based on utilizing stored reserves. The possession of these alternative survival strategies helps to explain the success of L. tenuis in environments subjected to unpredictable flooding depths.
Subject(s)
Floods , Lotus/physiology , Water/physiology , Air , Biomass , Carbohydrates/analysis , Organ Specificity , Plant Leaves/physiology , Plant Roots/physiology , Plant Shoots/anatomy & histology , Porosity , Soil , SolubilityABSTRACT
A remarkable diversity of ploidy, i.e., diploidy, triploidy, and diploid-triploid mosaicism, was found among the somatic and testicular cells in a natural population of the lizard Liolaemus chiliensis from central Chile. Intra pop ulation, intersexual, and intraindividual ploidy variation is reported. In contrast with other species of polyploid reptiles, 86% of L. chiliensis males were mosaics (2n/3n) and 14% were diploids; 33% of females were triploid, 57.1% were mosaics, and 9.5% were diploid. Among 21 specimens, no triploid males were found in this sample. In the mosaic males, the diploid and triploid spermatogonia both enter meiosis, producing both reduced and unreduced metaphase II spermatocytes, most of them euploids. We discuss the origin for this ploidy in this iguanid lizard.
Subject(s)
Lizards/genetics , Mosaicism , Polyploidy , Animals , Female , Genetic Variation , Geography , Karyotyping , Male , Meiosis , Models, Genetic , Sex CharacteristicsABSTRACT
Paciente de 34 años que consulto por poliartralgias, oligoartritis, Fenomeno de Raynaud y rash malar. Posteriormente se añadio debilidad muscular, edema bipalpebral, tumefaccion de manos y pies, y signo de Koebner positivo. Se realizo diagnostico de rosacea y vasculitis urticarina hipocomplementemica. Al año siguiente presento xeroftalmia, xerostomia y sequedad vaginal. Se investigo Sindrome de Sjogren Primario confirmandose tal diagnostico (AU)
Subject(s)
Raynaud Disease , Vasculitis, Leukocytoclastic, Cutaneous , Lupus Erythematosus, SystemicABSTRACT
Paciente de 34 años que consulto por poliartralgias, oligoartritis, Fenomeno de Raynaud y rash malar. Posteriormente se añadio debilidad muscular, edema bipalpebral, tumefaccion de manos y pies, y signo de Koebner positivo. Se realizo diagnostico de rosacea y vasculitis urticarina hipocomplementemica. Al año siguiente presento xeroftalmia, xerostomia y sequedad vaginal. Se investigo Sindrome de Sjogren Primario confirmandose tal diagnostico
Subject(s)
Lupus Erythematosus, Systemic , Raynaud Disease , Vasculitis, Leukocytoclastic, CutaneousABSTRACT
El presente trabajo tiene como finalidad la evoluación del tratamiento OMS en pacientes multibacilares a través de dos grupos. Un grupo conformado por 18 pacientes tratados con el plan OMS, y un grupo de 7 pacientes tratados con el plan OMS modificado, siendo este último una variante del plan OMS en el cual la rifampicina es utilizada con una dosis de 600 mg. por día durante un lapso de dos meses y posteriormente continuada con una dosis de 600 mg. por mes. Asimismo, se evalúan en el presente trabajo las baciloscopías con muestras de mucus nasal, lóbulo de orega, musclo y de la impronta de piel, en relación al índice morfológico y al número de bacilos encontrados; las histopatologías, teniendo en cuenta los cambios histológicos y el número y morfología bacilar;los episodios reaccionales; las reacciones reversales y los colaterales de la medicación empleada.
