Hypoxia modulates cyclin and cytokine expression and inhibits peripheral mononuclear cell proliferation.

Previously, we found that hypoxia can deeply affect the production of cytokines in human peripheral mononuclear cells (PBMC). Here, we demonstrated that the cycle progression of hypoxic PBMC, cultured in the presence or not of a specific T cell activator such as phytohaemagglutinin (PHA), was delayed when compared with aerobic cultures. This delay was accompanied by a decrease of the expression of specific cyclins associated to cell cycle progression phases. Ribonuclease Protection Assay (RPA) studies reveal a decrease in the expression of cyclin A and B in PHA-stimulated PBMC kept for 40 hr under hypoxic condition (2% O(2)), when compared with aerobic cultures (20% O(2)). In concomitance, a decrease of cyclin D2 expression was present after 16 hr of hypoxic treatment. However, the decrease was transient and disappeared after 40 hr of hypoxic treatment. Furthermore, cyclin C expression was not affected by hypoxia. Hypoxia-induced cyclin modulation was accompanied by an increased synthesis of interleukin (IL)-2 and IL-4, analyzed by ELISA. By evaluating these results, it appears that hypoxia induces a growth suppressive state in mitogen-activated PBMC by inhibiting the synthesis of mitotic cyclins A and B. However hypoxic PBMC maintain their viability and capability of producing stimulatory cytokines, after mitogen treatment. This should be important in local hypoxia, usually associated with necrotic areas, in inflammation, and infections, where T lymphocyte capability of producing stimulatory cytokines is desirable.     

Apple Proliferation Epidemics Detected in Scab-Resistant Apple Trees

In the Friuli-Venezia Giulia, a region of Italy, where serious epidemics of apple proliferation (AP) are known to occur, varieties resistant to scab (Venturia inaequalis (Cke.) Wint.) are increasingly being used in new orchards. The most important cvs are Florina. Prima and Priscilla. These varieties were cultivated according to organic farming regimes with no insecticides used. The results obtained in two orchards during a 7-year period of investigation indicated that the three varieties resistant to scab are highly susceptible to AP. Florina was most susceptible (high infection rate) to AP while Priscilla was most sensitive (severely affected). The identification of the disease was based on symptom expression, DAPI (4–6-diamidino-2-phenylindole) fluorescence technique, electron microscopy observations and by polymerase chain reaction (PCR). Neither complete spontaneous recovery nor death of AP-infected plants was noticed. The pattern of natural diffusion of AP does not seem to be uniform, the affected trees may be in line or grouped in certain spots of the orchards. This may indicate the activity of a not very mobile vector. It can be concluded that planting of Florina, Prima and Priscilla should be discouraged in areas where AP is a problem, particularly when organic farming regimes are being applied.     

Involvement of reactive oxygen species in the oxidation of tyrosine and dopa to melanin and in skin tanning

The role of reactive oxygen (1O2 and O2-.) in skin photosensitization and tanning reaction has been examined. Riboflavin (RF), hematoporphyrin (HP), 3-carbethoxypsoralen (3-CP), and 8-methoxypsoralen (8-MOP), upon photoexcitation under aerobic conditions, produced singlet O2 (1O2). RF, 3-CP, and 8-MOP also produced superoxide anion (O2-.). Reactive O2 produced by photosensitized RF, 3-CP, and 8-MOP was found to oxidize tyrosine and dopa to dopachrome and subsequently their conversion to melanin. HP did not oxidize tyrosine to dopachrome, and 3-CP and RF revealed substantial oxidation of tyrosine. Dopa was oxidized to dopachrome and subsequently to melanin by all photosensitizers tested at a variable rate as follows: RF greater than 3-CP greater than HPD greater than 8-MOP. UVA alone and to a lesser extent UVB also produced 1O2 which induced the oxidation of tyrosine and dopa to dopachrome and subsequently to melanin. The production of dopachrome was higher with dopa compared to tyrosine under all irradiation conditions. These observations appear to have relevance to the O2-requiring immediate tanning reaction of the skin stimulated by solar radiation and in the induction of skin photosensitization.     

The role of ecosystem transpiration in creating alternate moisture regimes by influencing atmospheric moisture convergence

The terrestrial water cycle links the soil and atmosphere moisture reservoirs through four fluxes: precipitation, evaporation, runoff, and atmospheric moisture convergence (net import of water vapor to balance runoff). Each of these processes is essential for sustaining human and ecosystem well-being. Predicting how the water cycle responds to changes in vegetation cover remains a challenge. Recently, changes in plant transpiration across the Amazon basin were shown to be associated disproportionately with changes in rainfall, suggesting that even small declines in transpiration (e.g., from deforestation) would lead to much larger declines in rainfall. Here, constraining these findings by the law of mass conservation, we show that in a sufficiently wet atmosphere, forest transpiration can control atmospheric moisture convergence such that increased transpiration enhances atmospheric moisture import and results in water yield. Conversely, in a sufficiently dry atmosphere increased transpiration reduces atmospheric moisture convergence and water yield. This previously unrecognized dichotomy can explain the otherwise mixed observations of how water yield responds to re-greening, as we illustrate with examples from China's Loess Plateau. Our analysis indicates that any additional precipitation recycling due to additional vegetation increases precipitation but decreases local water yield and steady-state runoff. Therefore, in the drier regions/periods and early stages of ecological restoration, the role of vegetation can be confined to precipitation recycling, while once a wetter stage is achieved, additional vegetation enhances atmospheric moisture convergence and water yield. Recent analyses indicate that the latter regime dominates the global response of the terrestrial water cycle to re-greening. Evaluating the transition between regimes, and recognizing the potential of vegetation for enhancing moisture convergence, are crucial for characterizing the consequences of deforestation as well as for motivating and guiding ecological restoration.     

The evolution and ecology of multiple antipredator defences

Prey seldom rely on a single type of antipredator defence, often using multiple defences to avoid predation. In many cases, selection in different contexts may favour the evolution of multiple defences in a prey. However, a prey may use multiple defences to protect itself during a single predator encounter. Such “defence portfolios” that defend prey against a single instance of predation are distributed across and within successive stages of the predation sequence (encounter, detection, identification, approach (attack), subjugation and consumption). We contend that at present, our understanding of defence portfolio evolution is incomplete, and seen from the fragmentary perspective of specific sensory systems (e.g., visual) or specific types of defences (especially aposematism). In this review, we aim to build a comprehensive framework for conceptualizing the evolution of multiple prey defences, beginning with hypotheses for the evolution of multiple defences in general, and defence portfolios in particular. We then examine idealized models of resource trade-offs and functional interactions between traits, along with evidence supporting them. We find that defence portfolios are constrained by resource allocation to other aspects of life history, as well as functional incompatibilities between different defences. We also find that selection is likely to favour combinations of defences that have synergistic effects on predator behaviour and prey survival. Next, we examine specific aspects of prey ecology, genetics and development, and predator cognition that modify the predictions of current hypotheses or introduce competing hypotheses. We outline schema for gathering data on the distribution of prey defences across species and geography, determining how multiple defences are produced, and testing the proximate mechanisms by which multiple prey defences impact predator behaviour. Adopting these approaches will strengthen our understanding of multiple defensive strategies.     

Use of nuclear morphometry characteristics to distinguish between normal and abnormal cervical glandular histologies.

This is a methodological study exploring the use of quantitative histopathology applied to the cervix to discriminate between normal and cancerous (consisting of adenocarcinoma and adenocarcinoma in situ) tissue samples. The goal is classifying tissue samples, which are populations of cells, from measurements on the cells. Our method uses one particular feature, the IODs-Index, to create a tissue level feature. The specific goal of this study is to find a threshold for the IODs-Index that is used to create the tissue level feature. The main statistical tool is Receiver Operating Characteristic (ROC) curve analysis. When applied to the data, our method achieved promising results with good estimated sensitivity and specificity for our data set. The optimal threshold for the IODs-Index was found to be 2.12.     

Conformational properties of the N-terminal residues of S-peptide. I. The ribonuclease S′ system

The contribution of the 1–6 N-terminal sequence to the conformational properties of the S-peptide (the 1–20 sequence of ribonuclease A) was assessed by determining in the ribonuclease S′ system the helical content and the binding capability of synthetic [Orn¹⁰]-S-peptide analogs, in which lysine¹, glutamic² and threonine³ were progressively deleted, alanine⁴ and alanine⁵were alternatively replaced by serine, and alanine⁶ was substituted by serine or proline. Both the deletion of the three N-terminal residues and the alanine⁶/proline replacement produces the loss of the helical structure up to lysine⁷. No or minor effects are found in all other cases. From the comparison of the binding data, the energy for the conformational stabilization of the N-terminal region was calculated to amount to 1.4 kcal/mol. The results are discussed in comparison with the known x-ray data of the enzyme, with some predictive rules of secondary structure which were applied to this region and with the known phylogenetic variance of the residues in this region.     

Biosynthesis of the sesquiterpenoid ageratriol

Ageratriol is biosynthesized from agerol through a diepoxide derivative. Mevalonic acid incorporation revealed that the formation of the isopropenylic double bond is not stereospecific.