Size-dependent mortality in a Neotropical savanna tree: the role of height-related adjustments in hydraulic architecture and carbon allocation

Size-related changes in hydraulic architecture, carbon allocation and gas exchange of Sclerolobium paniculatum (Leguminosae), a dominant tree species in Neotropical savannas of central Brazil (Cerrado), were investigated to assess their potential role in the dieback of tall individuals. Trees greater than ∼6-m-tall exhibited more branch damage, larger numbers of dead individuals, higher wood density, greater leaf mass per area, lower leaf area to sapwood area ratio (LA/SA), lower stomatal conductance and lower net CO₂ assimilation than small trees. Stem-specific hydraulic conductivity decreased, while leaf-specific hydraulic conductivity remained nearly constant, with increasing tree size because of lower LA/SA in larger trees. Leaves were substantially more vulnerable to embolism than stems. Large trees had lower maximum leaf hydraulic conductance ( K _leaf) than small trees and all tree sizes exhibited lower K _leaf at midday than at dawn. These size-related adjustments in hydraulic architecture and carbon allocation apparently incurred a large physiological cost: large trees received a lower return in carbon gain from their investment in stem and leaf biomass compared with small trees. Additionally, large trees may experience more severe water deficits in dry years due to lower capacity for buffering the effects of hydraulic path-length and soil water deficits.     

EXPERTS VERSUS CONSUMERS: A CRITIQUE

In a recent paper Moskowitz (1996) refuted the notion that consumers are incapable of validly rating the sensory aspects of products. An analysis of this paper reveals that references are not presented to support his introduction, there is lack of experimental detail, parameters to compare panels were questionable, the degree of expertise of the expert panel is put to doubt and the model proposed to relate data between panels was not compared to existing models.     

Supercooling along an Altitudinal Gradient in Espeletia schultzii, a Caulescent Giant Rosette Species

Rada, F., Goldstein, G., Azocar, A. and Torres, F. 1987. Supercoolingalong an altitudinal gradient in Espeletia schultzii, a caulescentgiant rosette species.—J. exp. Bot. 38: 491–497. Tropical high Andes plants may be exposed to sub-zero temperaturesany night of the year. These plants have to rely on mechanismswhich protect them from these environmental conditions but atthe same time allow their growth and development. Supercoolinghas been found to be the principal avoidance mechanism in leavesof the caulescent giant rosette genus Espeletia in the Andes.We report here the differences in supercooling capacity andcold injury in several Espeletia schultzii populations growingalong an altitudinal gradient. The relationships between supercooling,water potential and leaf anatomy were also investigated. Thesupercooling capacity increased and injury temperature decreasedfrom lower to higher elevation populations. These changes maybe explained in terms of physiological, morphological and anatomicalcharacteristics of the leaves. Key words: Espeletia schultzii, supercooling, freezing avoidance mechanisms     

Effect of Gossypol on Trypomastigotes and Amastigotes of Trypanosoma cruzi

Bloodstream Trypanosoma cruzi trypomastigotes isolated from infected mice undergo reduction of motility and structural damages after 5 to 45 min exposure to gossypol at concentrations ranging from 5 to 50 μM. When 1% serum albumin is added to the incubation medium, no alterations of parasites are observed, even with 100 μM gossypol. Intracellular T. cruzi amastigotes in infected Vero cell cultures exposed to 5 μM gossypol for 2 h do not show changes. Incubation with 5 μM gossypol for 48 h produces complete disruption of host cells; however, the amastigotes they contain show only mineor alterations. The observations indicate that, in protein-rich media, gossypol is complexed into associations which have no activity on the different forms of the T. cruzi biological cycle.     

Impression Cytology In Patients With Keratoconjunctivitis Sicca

Impression cytology is a simple and painless procedure that allows the collection of the superficial layers of the conjunctival epithelium. Each sample is assigned a grade of epithelial metaplasia, and goblet cell density is calculated in each one. We have studied the superior and temporal bulbar conjuctiva of dry eyes and have compared it with that of normal controls. In normal and dry eyes we find a statistically significant difference both in goblet cell density and grade of metaplasia, between superior and temporal bulbar conjunctiva. the differences in grade of metaplasia and goblet cell density between normal and dry eyes are significant in the superior conjunctiva, but in the temporal conjunctiva we only find significant differences in grade of metaplasia.     

Midday stomatal conductance is more related to stem rather than leaf water status in subtropical deciduous and evergreen broadleaf trees

Midday depressions in stomatal conductance (g_s) and photosynthesis are common in plants. The aim of this study was to understand the hydraulic determinants of midday g_s, the coordination between leaf and stem hydraulics and whether regulation of midday g_s differed between deciduous and evergreen broadleaf tree species in a subtropical cloud forest of Southwest (SW) China. We investigated leaf and stem hydraulics, midday leaf and stem water potentials, as well as midday g_s of co‐occurring deciduous and evergreen tree species. Midday g_s was correlated positively with midday stem water potential across both groups of species, but not with midday leaf water potential. Species with higher stem hydraulic conductivity and greater daily reliance on stem hydraulic capacitance were able to maintain higher stem water potential and higher g_s at midday. Deciduous species exhibited significantly higher stem hydraulic conductivity, greater reliance on stem capacitance, higher stem water potential and g_s at midday than evergreen species. Our results suggest that midday g_s is more associated with midday stem than with leaf water status, and that the functional significance of stomatal regulation in these broadleaf tree species is probably for preventing stem xylem dysfunction.     

Preservation of Solanum pimpinellifolium genomic fragments in recombinant genotypes improved the fruit quality of tomato

Five recombinant inbred lines obtained from the F₂ generation of an interspecific cross between cultivar, Caimanta (Cai, Solanum lycopersicum) and wild accession, LA722 (P, S. pimpinellifolium) were crossed to obtain the second cycle hybrids (SCH). Eleven fruit quality traits were assessed in evaluating phenotypic variability among genotypes P, Cai, F₁ (Cai × P), five RILs, and 10 SCH. One of the five recombinant inbred lines and three SCH had higher values than P, as the best genotype for shelf life. Sequence-related amplified polymorphism was used as the molecular method for detecting polymorphism among these 18 genotypes. The percentage of polymorphism in RILs and SCH was 61% and 66% respectively. Moreover, some bands detected in P were present in SCH. Several multivariate analyses were performed to find agreement between the phenotypic variability observed for fruit quality traits and the polymorphism obtained from sequence-related amplified polymorphism markers. A general Procrustes analysis estimated that there was a consensus proportion of 75% between phenotypic and molecular data. There was considerable preservation of some bands from the wild genotype, which could increase the variability in fruit quality traits in populations where the genetic diversity is limited.     

Levels of IL-17F and IL-33 correlate with HLA-DR activation in clinical-grade human bone marrow–derived multipotent mesenchymal stromal cell expansion cultures

Background aims

Multipotent mesenchymal stromal cell (MSC)-based medicines are extensively investigated for use in regenerative medicine and immunotherapy applications. The International Society for Cell and Gene Therapy (ISCT) proposed a panel of cell surface molecules for MSC identification that includes human leukocyte antigen (HLA)-DR as a negative marker. However, its expression is largely unpredictable despite production under tightly controlled conditions and compliance with current Good Manufacturing Practices. Herein, we report the frequency of HLA-DR expression in 81 batches of clinical grade bone marrow (BM)-derived MSCs and investigated its impact on cell attributes and culture environment.

Integrating Horizontal Gene Transfer and Common Descent to Depict Evolution and Contrast It with “Common Design”1

ABSTRACT. Horizontal gene transfer (HGT) and common descent interact in space and time. Because events of HGT co‐occur with phylogenetic evolution, it is difficult to depict evolutionary patterns graphically. Tree‐like representations of life's diversification are useful, but they ignore the significance of HGT in evolutionary history, particularly of unicellular organisms, ancestors of multicellular life. Here we integrate the reticulated‐tree model, ring of life, symbiogenesis whole‐organism model, and eliminative pattern pluralism to represent evolution. Using Entamoeba histolytica alcohol dehydrogenase 2 (EhADH2), a bifunctional enzyme in the glycolytic pathway of amoeba, we illustrate how EhADH2 could be the product of both horizontally acquired features from ancestral prokaryotes (i.e. aldehyde dehydrogenase [ALDH] and alcohol dehydrogenase [ADH]), and subsequent functional integration of these enzymes into EhADH2, which is now inherited by amoeba via common descent. Natural selection has driven the evolution of EhADH2 active sites, which require specific amino acids (cysteine 252 in the ALDH domain; histidine 754 in the ADH domain), iron‐ and NAD⁺ as cofactors, and the substrates acetyl‐CoA for ALDH and acetaldehyde for ADH. Alternative views invoking “common design” (i.e. the non‐naturalistic emergence of major taxa independent from ancestry) to explain the interaction between horizontal and vertical evolution are unfounded.