Genetic relationships and hybrid vigour in olive (Olea europaea L.) by microsatellites

The olive (Olea europaea) is one of the most important oleaginous crops of the Mediterranean basin. Increased demand for olive oil creates a need for new olive varieties to help meet the requirements of the global market. However, olive breeding has been handicapped by such varied challenges as a prolonged juvenile period, agrotechnical problems and insufficient genetic knowledge. The use of DNA markers has the potential to overcome these problems and increase the effectiveness of classical breeding programmes. In this study, co‐dominant polymorphic simple sequence repeats (SSRs) were used as markers to analyse the genetic relationships between several local and other ‘non‐native’ olive cultivars. Cluster analysis revealed four major groups among the 15 cultivars examined in this study. Table and oil cultivars were clustered in different groups. However, the clusters did not differentiate between cultivars of different geographical origins. In addition, we used the data gathered to analyse genetic relationships to evaluate the effects of heterosis in agricultural traits. Genetic distances between cultivars were determined based on the SSR genotype data and were used for evaluating the possible effects of heterosis in various F₁ populations. Interestingly, phenotypic data of F₁ progenies from crosses between different cultivars indicated the potential effects of heterosis as expressed in several traits. Genetic distance between parents was significantly correlated to F₁ performance for three traits: percentage of dry fruit weight, oil content and commercial oil production. Thus, crosses between olive cultivars exhibiting relatively extensive genetic distances one from the other are expected to result in better progeny performance in future Olea breeding programmes. Our study linked assessment of biodiversity of commercial olive cultivars with the application of this information in olive breeding programmes for selection of specific parents to generate superior new cultivars.     

Synaptic theory of working memory

It is usually assumed that enhanced spiking activity in the form of persistent reverberation for several seconds is the neural correlate of working memory. Here, we propose that working memory is sustained by calcium-mediated synaptic facilitation in the recurrent connections of neocortical networks. In this account, the presynaptic residual calcium is used as a buffer that is loaded, refreshed, and read out by spiking activity. Because of the long time constants of calcium kinetics, the refresh rate can be low, resulting in a mechanism that is metabolically efficient and robust. The duration and stability of working memory can be regulated by modulating the spontaneous activity in the network.     

Fatty Acid Production and Direct Acyl Transfer through Polar Lipids Control TAG Biosynthesis during Nitrogen Deprivation in the Halotolerant Alga Dunaliella tertiolecta

The aims of this work were to evaluate the contribution of the free fatty acid (FA) pool to triacylglyceride (TAG) biosynthesis and to try to characterize the mechanism by which FA are assimilated into TAG in the green alga Dunaliella tertiolecta. A time-resolved lipidomic analysis showed that nitrogen (N) deprivation induces a redistribution of total lipidome, particularly of free FA and major polar lipid (PL), in parallel to enhanced accumulation of polyunsaturated TAG. The steady-state concentration of the FA pool, measured by prolonged ¹⁴C-bicarbonate pre-labeling, showed that N deprivation induced a 50% decrease in total FA level within the first 24 h and up to 85% after 96 h. The abundance of oleic acid increased from 50 to 70% of total free FA while polyunsaturated FA (PUFA) disappeared under N deprivation. The FA flux, measured by the rate of incorporation of ¹⁴C-palmitic acid (PlA), suggests partial suppression of phosphatidylcholine (PC) acyl editing and an enhanced turnover of the FA pool and of total digalactosyl-diacylglycerol (DGDG) during N deprivation. Taken together, these results imply that FA biosynthesis is a major rate-controlling stage in TAG biosynthesis in D. tertiolecta and that acyl transfer through PL such as PC and DGDG is the major FA assimilation pathway into TAG in that alga and possibly in other green microalgae. Increasing the availability of FA could lead to enhanced TAG biosynthesis and to improved production of high-value products from microalgae.     

Effect of fruit size and yield on the fruit-removal-force within and between olive cultivars

The fruit-removal-force (FRF) of green mature fruit on trees of 21 olive cultivars (Olea europaea) was determined. A high positive correlation was found between fruit size and FRF, and between fruit size and the thickness of the fruit stalks. The natural FRF was not cultivar-dependent, but was determined by the mechanics of the stalk. All cultivars tested responded to ethephon. The degree of FRF reduction due to ethephon treatments was cultivar-dependent and was generally independent of fruit stalk diameter. The amount of yield per tree had no direct effect on the FRF of the fruits except via fruit size.     

Detection and counting of flowers on apple trees for better chemical thinning decisions

Precision Agriculture - Accurate chemical thinning of apple trees requires estimation of their blooming intensity, and determination of the blooming peak date. Performing this task, as of...     

Fluid beds: at last, challenging two entrenched practices

Originating in the 1920' s and 1930's, two distinct fluidization arts have emerged, one for treating coarse solids and the other for fine powders. Fluidization research has tended to focus on bubbling beds of coarse solids, but designers of such beds for burning coal have learned to appreciate the importance of combustion of fine char particles in the freeboard. Designers of successful processes for powders have focused on bubble suppression. Since about 1980, combustion fluid beds of both types are challenging the conventional pulverized-coal boiler; they provide better means for controlling emissions from the combustion of high-sulfur fuels. Progress in the "bubbleless" fluidization of fine powders is increasing the fluid bed's competitiveness with the fixed-bed catalytic reactor. Efforts to advance the fluid bed for catalysis, besides increasing gas velocities beyond levels that most researchers have used in the past, must include systematic study of the level of fine particles smaller than 40 micrometers.