Sucrose and fructan metabolism in wheat roots at chilling temperatures

Sucrose and fructan metabolism were studied in wheat ( Triticuin aotiirum L. cv. Tribal 800) roots during a period at chilling temperature. Enzyme activities related to fructan and sucrose metabolism were measured. Sucrose-sucrose fructosyl transfer-ase (EC 2.4.1.99) activity increased more than 25-fold when plants were cooled to 4°C. Sucrose synthase (EC 2.4.1.13) and sucrose-phosphate synthase (EC 2.4.1.14) activities also increased, but low temperatures had no significant effect on invertaso (EC 3.2.1.26) or on fructan hydrolase (EC 3.2.1.26) activities. The accumulation pattern of fructan in roots was different to that in leaves. In roots chilling stimulated the synthesis of fructans of high degree of polymerization.     

An Ustilago maydis Mutant Partially Blocked in P45014DM Activity Is Hypersensitive to Azole Fungicides

An Ustilago maydis ergosterol biosynthesis mutant (A14) which is partially blocked in sterol 14alpha-demethylase (P45014DM) activity is described. This mutant accumulated the abnormal 14alpha-methyl sterols, eburicol, 14alpha-methylfecosterol, and obtusifoliol, along with significant amounts of ergosterol. Although the A14 mutant grew nearly as well as the wild type, it was impaired in cell extension growth, which indicated a dysfunction in apical cell wall synthesis. The mutant was also found to be hypersensitive to the azole fungicides penconazole and tebuconazole.     

Hexazonium pararosaniline as a fixative for animal tissues

Hexazonium pararosaniline is a valuable reagent that has been used in enzyme activity histochemistry for 50 years. It is an aqueous solution containing the tris-diazonium ion derived from pararosaniline, an aminotriarylmethane dye, and it contains an excess of nitrous acid that was not consumed in the diazotization reaction. Other investigators have found that immersion for 2 min in an acidic (pH 3.5) 0.0015 M hexazonium pararosaniline solution can protect cryostat sections of unfixed animal tissues from the deleterious effects of aqueous reagents such as buffered solutions used in immunohistochemistry, while preserving specific affinities for antibodies. In the present investigation hexazonium pararosaniline protected lymphoid tissue and striated muscle against the damaging effects of water or saline. The same protection was conferred on unfixed sections treated with dilute nitrous or hydrochloric acid in concentrations similar to those in hexazonium pararosaniline solutions. Model tissues (solutions, gels or films containing gelatin and/or bovine albumin) responded predictably to well known cross-linking (formaldehyde) or coagulant (mercuric chloride) fixatives. Hexazonium pararosaniline solutions prevented the dissolution of protein gels in water only after 9 or more days of contact, during which time considerable swelling occurred. It is concluded that there is no evidence for a “fixative” action of hexazonium pararosaniline. The protective effect on frozen sections of unfixed tissue is attributable probably to the low pH of the solution.     

Is cooperativeness readable in static facial features? An inter-cultural approach

There is evidence in the literature that non-verbal physical features are used as cues for a propensity to cooperate. However, further studies of the human ability to visually detect cooperativeness are required. In particular, the existence of static facial cues of altruism remains questionable. Moreover, an investigation of both sex differences and cross-cultural applicability with respect to altruism detection skills is crucial in the context of the evolution of human cooperation. In this study, we used both a public good game and a charitable contribution to assess the cooperativeness of 156 men and 172 women in rural Senegal and took facial photographs of these individuals. The second portion of the study was conducted in France. In total, 194 men and 171 women were asked to distinguish the most and least selfish individual from a series of 80 pairs of Senegalese facial photographs, each pair consisting of the highest and the lowest contributor from a group in the public good game. Using mixed modeling techniques, we controlled for facial masculinity, age and socio-economic status. For male pairs, both male and female French raters were able to identify more often than by chance which individual made the smallest contribution to the public good in each group; however, detection was not successful with female faces. These results suggest that sex-specific traits are involved and that only male facial traits indicating cooperative skills are, at least inter-culturally, readable. The specific facial traits involved are investigated. However, the charitable contribution was not correlated with the contribution to the public good, and further work is necessary to identify which specific altruistic traits are detectable and to assess the generality of these results.     

Deficit irrigation and fertigation practices in olive growing: Convergences and divergences in two case studies

Abstract

The response of mature olive (Olea europaea L.) trees to both regulated deficit irrigation and fertigation was studied for some consecutive years in sub-humid (Italy) and semi-arid conditions (Spain). All cultivars tested in these experiments were preferentially for table olive consumption (pickling and double-aptitude). Data from these long-term studies on field-grown, mature trees are summarized for assessing common effects of water and nutrient supply on plant behaviour and fruit yield. Seasonal yield variations were observed, and showed that the effect of irrigation treatments was somewhat more gradual in the “on” than in the “off” year. Differences amongst cultivars were always marked. Dry matter accumulation in pulp and pit was positively affected by progressively increasing the amount of water supplied to plants, regardless of years and cultivars. The ratio between pulp and pit fresh weight was negatively affected by irrigation, while fruit size was positively influenced by the gradual increase of irrigation water. Average nitrogen levels in leaves were generally above the deficiency threshold at both experimental plantations. Crop yield was not consistently increased by addition of soil nutrients. The effect of fertigation treatments was relatively uninfluential on oil accumulation in fruits. However, polyphenols in oil samples decreased progressively as the addition of nutrients increased. Critical aspects and strategic decisions in modern olive growing are the selection of cultivar, the supply of water, the option of fertilization, together with other orchard management practices. In this paper we outline various aspects of long-term studies in experimental olive plantations with the aim of highlighting inter-regulatory processes, involving plant growth and crop yield, which must be taken into account when planning future field research and modelling exercises.     

Tree-ring wood anatomy and stable isotopes show structural and functional adjustments in olive trees under different water availability

Background and Aims

Olive tree (Olea europaea L.) is a drought-tolerant tree species cultivated in Mediterranean-type environments. Although it is tolerant to drought, dry conditions decrease its productivity. A thorough analysis of the hydraulic architecture and wood anatomical plasticity, as well as of their physiological significance, is needed to understand how olive trees will adapt to the predicted increase in frequency and severity of drought in the Mediterranean region.

Methods

Dendrochronological, stable isotopic (δ¹³C, δ¹⁸O) and wood anatomical analyses were applied to understand how different water availability can affect wood stem structure and function, in rainfed and irrigated at 100 % of crop evapotranspiration (ETc) olive trees in an experimental orchard close to Benevento (Italy) from 1992 to 2009.

Results

Dendrochronological data indicate that cross-dating and synchronization of ring-width time series in olive tree is possible. After the start of irrigation, significantly more negative δ¹³C and lower δ¹⁸O values were recorded in irrigated trees indicating higher stomatal conductance and transpiration rates. Increased water balance induced the formation of a higher number of vessels with higher diameter.

Conclusions

Water balance variations affected wood anatomy and isotopic composition. Anatomical analyses detected structural and functional adjustments in rainfed trees that produced more vessels with lower diameter to prevent cavitation. Isotopic analyses confirmed that irrigated trees continuously showed enhanced transpiration rates.     

Differential ozone sensitivity interferes with cadmium stress in poplar clones

Information on plant responses to combined ozone and cadmium stresses are scarce and limited to herbaceous species. In this research, two poplar clones (I-214 and Eridano), differently sensitive to O₃, were grown for 5 weeks in pots supplied with 0, 53.5, and 160.5 mg(Cd) kg^?1 (soil d.m.) and then exposed to 15-d O₃ fumigation (0.06 mm³ dm^?3, 5 h a day). The effects of the two stressors, alone or in combination, on Cd, Ca, Fe, and Zn accumulation in above-nad below-ground organs, photosynthesis, leaf pigments, and accumulation of H₂O₂ and NO were investigated. Cadmium induced a reduction in stomatal conductance and a significant accumulation of H₂O₂ and NO in both clones nad negatively affected the carotenoid content in I-214. Ozone, on the other hand, counteracted Cd accumulation in the above-ground organs and significantly increased the xanthophyll de-epoxidation state indicating photoinhibition in O₃-treated plants. Surprisingly, O₃ alone or in combination with Cd decreased H₂O₂ accumulation in I-214. The NO production was generally stimulated by Cd, whereas it decreased following O₃ exposure in I-214. The overall data indicate that Cd and O₃ induced clone specific responses. Moreover, when they were applied in combination, antagonistic rather than synergistic effects were observed.