Evaluation of actual evapotranspiration of a Quercus ilex L. stand by the Bowen Ratio-Energy Budget method

Actual evapotranspiration from a closed-canopy Quercus ilex L. stand has been estimated by applying the Bowen Ratio-Energy Budget method. Daily water loss was 3.5 mm day^–1, with a peak rate near 0.6 mm hour^–1. The phenomenon of thermal inversion, quite common in mediterranean climates, seemed to play a significant role in reducing evapotranspiration, by promoting dew formation and delaying the establishment of fluxes of latent and sensible heat away from the canopy. Dew, which may form over many hours in the night, appears to be a major sink of available energy in the early morning and may represent a useful water source for stressed foliage. The alternating processes of condensation and evaporation may have a beneficial effect on the closed stand micro-environment.     

Synthesis,Enzymatic Resolution,and Stereochemical Characterization of Isoparaconic Acid Derivatives: A Combined Experimental and Theoretical Investigation

Enantiomerically enriched isoparaconic acid derivatives were obtained by kinetic enzymatic resolution. To explain the solvent dependence observed for their optical rotatory power a computational investigation of their chiroptical properties was performed. Chirality 26:640–650, 2014. © 2014 Wiley Periodicals, Inc.     

First chemoenzymatic synthesis of (+)-2-carboxypyrrolidine-3-acetic acid, the nucleus of kainoid amino acids

The distinctive nucleus of kainoid amino acids, (2S,3R)-(+)-2-carboxypyrrolidine-3-acetic acid 6, was synthesized by a chemoenzymatic process, exploiting the diastereomeric cis/trans methyl pyroglutamate derivatives 10a-c/11a-c as key intermediates. These mixtures, when subjected to a kinetic resolution mediated by α-chymotrypsin, reacted diastereo-, regio-, and enantioselectively to give the trans derivatives (+)-10a-c possessing the correct (2S,3R) configuration. Subsequently, the desired product (2S,3R)-(+)-6 could be obtained after well-established transformations.     

Enzymatic Resolution of α‐Methyleneparaconic Acids and Evaluation of their Biological Activity

Both enantiomers of three biologically relevant paraconic acids—MB‐3, methylenolactocin, and C75—were obtained with enantioselectivities up to 99% by kinetic enzymatic resolutions. Good enantiomeric excesses were obtained for MB‐3 and methylenolactocin, using α‐chymotrypsin and aminoacylase as enantiocomplementary enzymes, while C75 was resolved with aminoacylase. They all were evaluated for their antiproliferative, antibacterial, and antifungal activities, showing weak effects and practically no difference between enantiomers in each case. At high concentrations (16–64 µg/mL), (–)‐ C75 acted as an antimicrobial agent against Gram‐positive bacteria. Chirality 27:239–246, 2015. © 2015 Wiley Periodicals, Inc.     

Optically Active α‐Phenylethylamine as Efficient Organocatalyst in the Solvent‐free Reactions Between 2,3‐Butanedione and Conjugated Nitroolefins

(R)‐(+) and (S)‐(?)‐1‐phenylethylamine have been shown to promote highly diastereoselective and complementary enantioselective formal [3 + 2]carbocyclization reactions between 2,3‐butanedione and conjugated nitroalkenes with formation of enantiomerically rich 2‐hydroxy‐3‐nitrocyclopentanone derivatives. The reactions were carried out both in solvent and under solvent‐free conditions. The absolute configurations of the products were assigned by X‐ray and circular dichroism spectra analyses. Chirality 24:1005–1012, 2012. © 2012 Wiley Periodicals, Inc.     

Solvent effects on the conformational distribution and optical rotation of gamma-methyl paraconic acids and esters

A computational investigation of the optical rotatory power of cis and trans 2-methyl-5-oxo-tetrahydro-3-furancarboxylic acids and the corresponding methyl and ethyl esters is presented. Solvent effects on both the conformational space and the rotatory power are analyzed by comparing results obtained in vacuo with those computed--using the Polarizable Continuum Model--in methanol. A comparison with experimental observations for the optical rotatory power of the title compounds in methanol is also carried out, in a few cases also for several wavelengths. Agreement between theory and experiment is in all cases excellent, in particular when solvent effects are included both in the geometry optimization and in the calculation of the OR, thus confirming the validity of the computational procedure adopted, even for this challenging family of floppy molecules.     

The ecology of the Mediterranean stony coral Cladocora caespitosa (Linnaeus, 1767) in the Gulf of Trieste (northern Adriatic Sea): a 30-year long story

Cladocora caespitosa is an endemic coral of the Mediterranean Sea and an important carbonate bioconstructor that adds 3D complexity to the habitat, thus increasing marine biodiversity. Despite its important role in the ecosystem, the real status of the population along most of the Mediterranean coastline is still poorly investigated and very little is known about the resilience of the species. Using non-destructive visual surveys, colonies of C. caespitosa were investigated by SCUBA diving in 2013 and 2015 at seven sites of the northern Adriatic Sea (southern part of the Gulf of Trieste). Data about colony size, index of sphericity and corallite diameter were collected. Almost all biometrical parameters differed significantly among sampling sites, showing low occurrence of the larger size classes compared to the abundance of small-sized colonies. This pattern of distribution is typical of long-lived organisms. The positively skewed colony size distribution could be due to both a high mortality rate of small colonies unable to reach larger size classes, and to a high fragmentation rate of colonies, related to a strong hydrodynamic forces. The northern Adriatic population of C. caespitosa has previously been investigated by Schiller, who reported size and abundance data of colonies from one site, at a depth range of 2–5?m. We compared these data with our findings from the same sampling site, adding new information about the ecology of C. caespitosa. After a 30-year period, the comparison shows a change in the size distribution of colonies, with a decrease of the small class and an increase of the medium class of colonies. In view of these conclusions, further assessments are required in order to evaluate the trend of the northernmost C. caespitosa population in the Mediterranean Sea.     

Hormonal responses to partial drying of the root system of Helianthus annuus

Plants of Helianthus annuus were pot-grown in soil, with approximately30% of the root system protruding through the base. After 7d, the upper part of the root system of half of the plants wasexposed to drought (internal roots) while the lower part waskept in aerated nutrient solution (protruding root). The treatmentrapidly reduced the internal roots' water content from 26.1to 21.9 g g^–1 dry weight (DW), while in protruding rootsof stressed plants it slowly and continuously decreased from31.9 to 25.2 g g^–1 DW. Leaf water content rapidly decreasedin treated plants from 7.4 to 6.4 g g^–1 DW in the first2d and then reached a plateau. In stressed plants leaf stomatalresistance was significantly higher in the first 3 d while leafwater potential was lower only on the last day. Abscisic acid (ABA) concentration in treated plants increasedsignificantly compared to the controls. In treated internalroots, ABA rose from the first day, reaching a maximum of 1.48±0.49nmol g^–1 DW after 3 d. In treated protruding roots a maximumof 0.99±0.09 nmol g^–1 DW was reached after 1 d.ABA concentration in the xylem sap increased 2 d and 3 d afterthe start of soil drying, with a maximum of 113±12nmoll^–1 during the third day. The ABA rise in the leaves oftreated plants was less significant. Indol-3yl-acetic acid (IAA) concentration in internal rootsof treated plants reached a maximum of 22.54±3.34 nmolg^–1 DW on the third day, then decreased dramatically.The protruding root system of control plants showed a maximumvalue of 16.05±1.77 nmol g^–1 DW on the sixth day. Little difference in cytokinin content of xylem sap was notedbetween control and treated plants. Hormonal variations in different parts of the plant are discussedin relation to drought stress. Key words: Soil drying, roots, ABA, IAA, cytokinins     

Termination of pupal diapause in the pine processionary moth Thaumetopoea pityocampa

Diapause development is a complex process involving several eco‐physiological phases. Understanding these phases, especially diapause termination, is vital for interpreting the life history of many insect species and for developing suitable predictive models of population dynamics. The pine processionary moth is a major defoliator of pine and a vertebrate health hazard in the Mediterranean region. This species can display either univoltine or semivoltine development, with a pupal diapause extending from a few months to several years, respectively. Although the ecological and applied importance of diapause is acknowledged, its physiological regulation in either case remains obscure. In the present study, we characterize pre‐termination, termination and post‐termination phases of pupae developing as univoltine or remaining in prolonged diapause. Changes in metabolic activity are monitored continuously using thermocouples, comprising a novel method based on direct calorimetry, and periodically by use of O₂ respirometry. The two methods clearly detect diapause termination in both types of pupae before any visible morphological or behavioural changes can be observed. Univoltine individuals are characterized by an increase in metabolic activity from pre‐termination through to termination and post‐termination, ultimately resulting in emergence. Remarkably, a synchronous termination is observed in individuals that enter prolonged diapause instead of emerging; however, in these pupae, the increased metabolic activity is only transient. The present study represents a starting point toward understanding the eco‐physiology of diapause development processes in the pupae of the pine processionary moth.