Osmolality and non-structural carbohydrate composition in the secondary phloem of trees across a latitudinal gradient in Europe

Phloem osmolality and its components are involved in basic cell metabolism, cell growth, and in various physiological processes including the ability of living cells to withstand drought and frost. Osmolality and sugar composition responses to environmental stresses have been extensively studied for leaves, but less for the secondary phloem of plant stems and branches. Leaf osmotic concentration and the share of pinitol and raffinose among soluble sugars increase with increasing drought or cold stress, and osmotic concentration is adjusted with osmoregulation. We hypothesize that similar responses occur in the secondary phloem of branches. We collected living bark samples from branches of adult Pinus sylvestris, Picea abies, Betula pendula and Populus tremula trees across Europe, from boreal Northern Finland to Mediterranean Portugal. In all studied species, the observed variation in phloem osmolality was mainly driven by variation in phloem water content, while tissue solute content was rather constant across regions. Osmoregulation, in which osmolality is controlled by variable tissue solute content, was stronger for Betula and Populus in comparison to the evergreen conifers. Osmolality was lowest in mid-latitude region, and from there increased by 37% toward northern Europe and 38% toward southern Europe due to low phloem water content in these regions. The ratio of raffinose to all soluble sugars was negligible at mid-latitudes and increased toward north and south, reflecting its role in cold and drought tolerance. For pinitol, another sugar known for contributing to stress tolerance, no such latitudinal pattern was observed. The proportion of sucrose was remarkably low and that of hexoses (i.e., glucose and fructose) high at mid-latitudes. The ratio of starch to all non-structural carbohydrates increased toward the northern latitudes in agreement with the build-up of osmotically inactive C reservoir that can be converted into soluble sugars during winter acclimation in these cold regions. Present results for the secondary phloem of trees suggest that adjustment with tissue water content plays an important role in osmolality dynamics. Furthermore, trees acclimated to dry and cold climate showed high phloem osmolality and raffinose proportion.Peer reviewe

Diversity of trends of viremia and T-cell markers in experimental acute feline immunodeficiency virus infection.

International audienceOBJECTIVE: The early events of human immunodeficiency virus infection seem critical for progression toward disease and antiretroviral therapy initiation. We wanted to clarify some still unknown prognostic relationships between inoculum size and changes in various immunological and virological markers. Feline immunodeficiency virus infection could be a helpful model. METHODS: Viremia and T-cell markers (number of CD4, CD8, CD8β(low)CD62L(neg) T-cells, CD4/CD8 ratio, and percentage of CD8β(low)CD62L(neg) cells among CD8 T-cells) were measured over 12 weeks in 102 cats infected with different feline immunodeficiency virus strains and doses. Viremia and T-cell markers trajectory groups were determined and the dose-response relationships between inoculum titres and trajectory groups investigated. RESULTS: Cats given the same inoculum showed different patterns of changes in viremia and T-cell markers. A statistically significant positive dose-response relationship was observed between inoculum titre and i) viremia trajectory-groups (r = 0.80, p<0.01), ii) CD8β(low)CD62L(neg) cell-fraction trajectory-groups (r = 0.56, p<0.01). Significant correlations were also found between viremia and the CD4/CD8 ratio and between seven out of ten T-cell markers. CONCLUSIONS: In cats, the infectious dose determines early kinetics of viremia and initial CD8+ T-cell activation. An expansion of the CD8β(low)CD62L(neg) T-cells might be an early predictor of progression toward disease. The same might be expected in humans but needs confirmation

Preliminary Results of a Prospective Study of Testicular Sperm Extraction in Young Versus Adult Patients With Nonmosaic 47,XXY Klinefelter Syndrome

International audienc

Number of infected cats according to the virus strain and the inoculum titre.

<p>Number of infected cats according to the virus strain and the inoculum titre.</p

Aspect of the trajectories of viremia and changes in T-cell markers.

<p>Aspect of the trajectories of viremia and changes in T-cell markers.</p

Sex and age of cats by trajectory group for viremia and changes in T-cell markers.

<p>Sex and age of cats by trajectory group for viremia and changes in T-cell markers.</p

Criteria for the choice of the optimal number of trajectory-groups.

<p>Criteria for the choice of the optimal number of trajectory-groups.</p

Trajectory-groups.

<p>Trajectory-groups (with 95% confidence intervals) for viremia and changes in T-cell markers over time since contamination (in weeks). Viremia is expressed in log₁₀ of viral RNA copies per mL of plasma. The hatched area indicates the area below the virus detection threshold (1.9). Each T cell marker is expressed as the predicted value of log₁₀(<i>X</i>_w/<i>X</i>₀) where <i>X</i>₀ is the value at baseline and <i>X</i>_w the value at week <i>w</i> (1 to 12).</p

Cross-tabulation of trajectory-groups according to viremia and changes in T-cell markers during the 12-week period after FIV inoculation.

a<p>The content of each cell is the number of cats among the 102 cats of the study.</p

Polychoric correlation coefficients between groups of inoculum and trajectory-groups of viremia and changes in T-cell markers during the 12-week period after virus inoculation.

<p>Significance:</p>†<p>p<0.01,</p>*<p>p<0.05,</p><p>Polychoric correlations are not correlations between quantitative variables but correlations between ordinal variables; here, the trajectory-groups. For example, CD4 and CD8 are viewed as ordinal variables, each with three categories. Using the cross-tabulation of CD8 by CD4 given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0056135#pone-0056135-t004" target="_blank">Table 4</a>, a polychoric correlation of 0.88 means that cats that belong to group 3 for CD4 have a higher probability of belonging also to group 3 for CD8 than to the two other groups. Conversely, 0.08 means that cats that belong to group 3 for CD4 have a low probability of belonging to group 3 for CD4/CD8 ratio and could belong to any of the three groups for the CD4/CD8 ratio.</p