Seasonal Evolution of the Quality of Fresh Glasshouse Tomatoes under Mediterranean Conditions, as Affected by Air Vapour Pressure Deficit and Plant Fruit Load

Changes in yield and quality of fresh tomatoes in response toair vapour pressure deficit (VPD) and plant fruit load werestudied under Mediterranean summer conditions. Plants thinnedto three or six fruits per truss were grown in two compartments,one at a VPD below 1.5 kPa, the other without VPD control. Theseasonal trend in fruit yield and quality was assessed fromApril to September by weekly measurement of number, fresh weightand dry matter content of harvested fruits, together with theoccurrence of blossom-end-rot (BER) and cracking. On two occasions,in July and September, sugar and acid content was measured atthree ripening stages. The seasonal decrease in fresh yieldwas attenuated at low VPD, because of higher individual fruitfresh weight, especially at low fruit load. Low VPD decreasedoccurrence of BER but like low fruit load, it increased fruitcracking. Fruit dry matter content was lower at low VPD, butwas unaffected by fruit load. Sugar content and the ratio ofsugars:acids was increased at high VPD and low fruit load, withinteractive effects depending on season and ripening stage.The influence of VPD on acid content differed with fruit loadand also changed during ripening and between seasons. Resultsshowed that water was the main limiting factor for growth offruits picked in July; at this time, reducing fruit load topromote mean fruit size had negative effects on BER and cracking.Reducing VPD reduced BER but had a negative effect on crackingand diluted both the dry matter and sugar content. For fruitsharvested later in summer, these negative effects were attenuatedbecause fruit growth was also carbon limited. Copyright 2000Annals of Botany Company Lycopersicon esculentum Mill., tomato, water and carbon stress, yield, quality, dry matter, sugar, acid, BER, volatile composition     

The ras oncogene and tumour metastasis: observations on murine cells transfected with activated human c-Ha-ras

Transfection of cells with cloned genes or total genomic DNA offers a means for studying aspects of neoplastic behaviour. We have used this method to examine whether incorporation of the cloned 6.6-kilobase (kb) fragment of DNA containing the mutant c-Ha-ras human oncogene can confer metastatic capability on murine NIH 3T3 cells. Cells co-transfected with the mutated ras gene and the neomycin resistance marker pSV2neo were selected by culture in neomycin. On subcutaneous inoculation into MF 1 nude mice, these cells proved to be tumourigenic with short latent periods (approximately 14 days)--nude mice were used to circumvent immunological rejection of the mouse cells expressing the product of the human oncogene. Transfectants were capable of lung colonisation after intravenous injection, but there was no evidence of spontaneous metastasis at autopsy, or on histological examination of the lungs and other organs, 90 days after inoculation. Incorporation of the transfected oncogene was confirmed by Southern blotting and its expression by dot-blot hybridisation and immunoprecipitation. The results in this experimental system indicate that transfection of a mutated human ras oncogene into non-neoplastic 3T3 cells can confer part of the metastatic phenotype, namely lung colonisation, but is not by itself sufficient to induce spontaneous metastatic behaviour.     

Muscle hypertrophy and fast fiber type conversions in heavy resistance-trained women

Twenty-four women completed a 20-week heavy-resistance weight training program for the lower extremity. Workouts were twice a week and consisted of warm-up exercises followed by three sets each of full squats, vertical leg presses, leg extensions, and leg curls. All exercises were performed to failure using 6-8 RM (repetition maximum). Weight training caused a significant increase in maximal isotonic strength (1 RM) for each exercise. After training, there was a decrease in body fat percentage (p less than 0.05), and an increase in lean body mass (p less than 0.05) with no overall change in thigh girth. Biopsies were obtained before and after training from the superficial portion of the vastus lateralis muscle. Sections were prepared for histological and histochemical examination. Six fiber types (I, IC, IIC, IIA, IIAB, and IIB) were distinguished following routine myofibrillar adenosine triphosphatase histochemistry. Areas were determined for fiber types I, IIA, and IIAB + IIB. The heavy-resistance training resulted in significant hypertrophy of all three groups: I (15%), IIA (45%), and IIAB + IIB (57%). These data are similar to those in men and suggest considerable hypertrophy of all major fiber types is also possible in women if exercise intensity and duration are sufficient. In addition, the training resulted in a significant decrease in the percentage of IIB with a concomitant increase in IIA fibers, suggesting that strength training may lead to fiber conversions.     

Organic matter and nutrient cycling within an endemic birch stand in the Etna massif (Sicily):Betula aetnensis Rafin

At altitudes between 1300 m to 2100 m in the Etna massif (Sicily), an endemic species of theBetula genus,Betula aetnensis Rafin, grows in a well-defined microclimatical context. Aboveground biomass and nutrient content studies within one stand revealed no significant differences from the otherBetula species, normally found in colder more temperate climate regions.Throughout the studied sites, biomass production, nutrient cycling and various structural or physiological characteristics (leaf area index) varied very little.Other researches indicate that the originality ofBetula aetnensis lies more in the histological or anatomical characteristics of its water conducting system which enables the species to adapt to Mediterranean-climate summer droughts in the Etna massif.

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Riassunto Sull'Etna, tra 1300 e 2100 m d'altitudine, in una zona microclimaticamente ben definita del versante nordorientale, si rinviene laBetula aetnensis Rafin.Dallo studio della fitomassa e della mineralomassa aerea del bosco di Monte Baracca, è emerso che non vi sono differenze notevoli con le altre specie indagate del genereBetula, più caratteristiche dei climi temperati e freddi.La produzione di biomassa, cosi come la gestione degli elementi nutritivi, è molto simile ai diversi popolamenti già indagati, cosi come certe caratteistiche strutturali e fisiologiche (leaf area index).L'originalità dellaBetula aetnensis è da ricercarsi nel vantaggio che ne ricava, a livello endogeno, sfruttando le caratteristiche istologiche ed anatomiche del suo apparato conduttore, che le consentono un efficace ed eccellente adattamento alle condizioni di siccità estive particolari del clima mediterraneo del vulcano.

     

X-ray diffraction analysis of collagen fibers processed with glutaraldehyde and glycerol

Rat tail tendon collagen fixed with glutaraldehyde and treated with glycerol has been studied by X-ray diffraction technique. The evaluation of the distribution of the areas at higher and less density of molecular packing in the collagen fibrils has been carried out through the analysis of the intensity distribution of the low angle X-ray diffraction maxima. The results show that this treatment usually employed in the freeze-etching technique induces a modification of the degree of order in specific regions inside the axial period D.     

Lack of tropomyosin correlates with the absence of stress fibers in transformed rat kidney cells

We have utilized epithelial rat kidney cells and their Kirsten viral transformant (442) to examine the role of actin-binding proteins in cellular morphogenesis. Normal rat kidney cells are well spread while the transformed cells are more spherical, poorly adherent, and lack actin stress fibers (Rubin, R.W., Warren, R.H., Lukeman, D.S. and Clements, E. (1978) J. Cell Biol. 78, 28-35). By immunofluorescence, antitropomyosin prominently stains normal rat kidney cell stress fibers while only a weak, nonspecific fluorescence is observed in 442 cells. Using two-dimensional gel electrophoresis, tropomyosin can be detected in normal rat kidney cells homogenates. The tropomyosin subunits are enriched in Triton-extracted filamentous normal rat kidney cell models, and in extracts of normal rat kidney cell homogenate produced by using a rapid myosin affinity technique to isolate actin and actin-associated proteins. The identity of the tropomyosin subunits has been confirmed by electrophoretic mobility, lack of proline, and the peptide map generated by limited proteolysis. None of these techniques have detected tropomyosin in the corresponding 442 preparations. Our results suggest that the transformation of normal rat kidney cells has led to an overall reduction in tropomyosin content. This may be related to the inability of 442 cells to organize filamentous actin stress fibers.     

A global assessment of forest surface albedo and its relationships with climate and atmospheric nitrogen deposition

We present a global assessment of the relationships between the short‐wave surface albedo of forests, derived from the MODIS satellite instrument product at 0.5° spatial resolution, with simulated atmospheric nitrogen deposition rates (N_dep), and climatic variables (mean annual temperature T_m and total annual precipitation P), compiled at the same spatial resolution. The analysis was performed on the following five forest plant functional types (PFTs): evergreen needle‐leaf forests (ENF); evergreen broad‐leaf forests (EBF); deciduous needle‐leaf forests (DNF); deciduous broad‐leaf forests (DBF); and mixed‐forests (MF). Generalized additive models (GAMs) were applied in the exploratory analysis to assess the functional nature of short‐wave surface albedo relations to environmental variables. The analysis showed evident correlations of albedo with environmental predictors when data were pooled across PFTs: T_m and N_dep displayed a positive relationship with forest albedo, while a negative relationship was detected with P. These correlations are primarily due to surface albedo differences between conifer and broad‐leaf species, and different species geographical distributions. However, the analysis performed within individual PFTs, strengthened by attempts to select ‘pure’ pixels in terms of species composition, showed significant correlations with annual precipitation and nitrogen deposition, pointing toward the potential effect of environmental variables on forest surface albedo at the ecosystem level. Overall, our global assessment emphasizes the importance of elucidating the ecological mechanisms that link environmental conditions and forest canopy properties for an improved parameterization of surface albedo in climate models.     

Degradation of aromatic hydrocarbons by white-rot fungi in a historically contaminated soil

Phanerochaete chrysosporium NRRL 6361 and Pleurotus pulmonarius CBS 664.97 were tested for their ability to grow under nonsterile conditions and to degrade various aromatic hydrocarbons in an aged contaminated soil that also contained high concentrations of heavy metals. After 24 days fungal incubation, carbon-CO2 liberated, an indicator of microbial activity, reached a plateau. At the end of the incubation time (30 days), fungal colonization was clearly visible and was confirmed by ergosterol and cell organic carbon determinations. In spite of unfavorable pH (around 7.4) and the presence of heavy metals, both fungi produced Mn-peroxidase activity. In contrast, laccase and aryl-alcohol oxidase were detected only in the soil treated with P. pulmonarius CBS 664.97 and lignin-peroxidase in that with P. chrysosporium NRRL 6361. No lignin-modifying enzyme activities were present in non-inoculated soil incubated for 30 days (control microcosm). Regardless of the fungus employed, a total removal of naphtalene, tetrachlorobenzene, and dichloroaniline isomers, diphenylether and N-phenyl-1-naphtalenamine, was observed. Significant release of chloride ions was also observed in fungal-treated soil, in comparison with that recorded in the control microcosm. Both fungi led to a significant decrease in soil toxicity, as assessed using two different soil contact assays, including the Lepidium sativum L. germination test and the Collembola mortality test.