An approach to acorn production in Iberian dehesas

Acorn production is one of the most important products in silvopastoral systems in the Mediterranean region. In the present study we carried out two preliminary trials to analyze the distribution of production over time and the effect of pruning. The objective was to develop tools to manage this valuable resource within these systems. In the first part of the study, we analyzed the total acorn production of a holm oak stand, and its seasonal distribution (October–January) over two years (1997–1998 and 1998–1999) in five sites in the southwest of Spain. Mean total acorn production ranged from 590 to 830 kg ha⁻¹. There was considerable variation between the different sites and years studied, as was expected from studies on other oak species. A comparison was also made of acorn production, comparing annual acorn production between 40 pruned and 40 non-pruned trees, for the period 1994–1999. There was an interaction between ‘pruning treatment’ and ‘year’. Pruning, significantly decreased acorn production in all but two years when production was above the average, whereas production was not affected by pruning the three years that acorn yield was below the average. The study of acorn production and the analysis of the effect of pruning, needs to be studied over a longer time period.     

Lythrum hyssopifolia (lesser loosestrife) poisoning of sheep in Victoria

Objective To document an ovine disease attributed to the consumption of Lythrum hyssopifolia (lesser loosestrife). Procedures Historical and histological review of field and experimental cases. Results 1–20% mortality occurred in sheep flocks grazing paddocks where L. hyssopifolia was the predominant green vegetation. Well‐documented disease outbreaks occurred in summer on nine farms across Victoria between 1974 and 2002. Liver damage occurred in all nine outbreaks, with kidney damage in at least eight. Hepatocyte necrosis was usually zonal to midzonal (zone 2) in the liver samples from four farms and periacinar (zone 3) in those from three farms, but some livers showed only single‐cell necrosis. Multinucleate hepatocytes near necrotic areas were a feature in six cases. Proximal tubular epithelium appeared to be the primary renal target and brown granules were often present in renal tubules. Biochemical and histological evidence of liver and kidney damage was obtained from two sheep experimentally pen‐fed harvested L. hyssopifolia. Conclusion Chemicals in L. hyssopifolia are toxic to ovine hepatocytes and renal tubular epithelial cells.     

Assessment of Selected Quality Parameters of Epididymal Cat (Felis catus s. domestica,L. 1758) Sperm Using Flow Cytometry Method and Computer Assisted Sperm Analyser

The improvement of biotechnical methods connected with fast and precise semen quality assessment and its utilization in assisted reproductive techniques is an urgent necessity in felids. The aim of this study was to evaluate some quality parameters (i.e. the viability and share of cells with intact plasma membrane) of epididymal sperm of cats using the flow cytometry method and computer‐assisted sperm analysis (CASA) examination. The material consisted of epididymal spermatozoa flushed from 22 pairs of epididymes after routine neutering procedures obtained from domestic cats aged between 8 and 36 months. The epididymes were cut and incubated with an extender without egg yolk. The samples were assessed for sperm viability (Live/Dead Sperm Viability Kit^®), percentage of subtle membrane changes (Apoptosis Detection Kit^®) and motility using FACScalibur flow cytometer and assisted sperm analyser htm ivos version 12.2. The flow cytometry method revealed 71.3% and 84.4% of live sperm using Live/Dead Sperm Viability Kit and Apoptosis Detection Kit respectively. The population of early‐apoptotic and late‐apoptotic sperm were 0.8% and 1.1% respectively. The CASA examination found 51.5% of motile sperm. However, the motility examination under light microscope revealed 69.5% of motile sperm. The data revealed an indistinctive per cent of apoptotic cells and 18.9% and 15.6% of dead cells using Live/Dead Sperm Viability Kit and Apoptosis Detection Kit, respectively, which indicate that the sperm obtained after flushing the epididymis possess potential properties for further assisted reproduction techniques.     

Proinsecticides effective against insecticide-resistant peach-potato aphid (Myzus persicae (Sulzer))

A range of potential proinsecticides was synthesised and tested against insecticide-susceptible and -resistant clones of Myzus persicae (Sulzer). They were all esters of compounds known to be toxic or pharmacologically active, and were designed to have increased lipophilicity and to be subject to more rapid activation by hydrolysis in resistant than in susceptible aphids due to the increased amount of esterase present in the resistant clones. The most potent toxins were esters of monofluoroacetic acid. When applied topically, the toxicity of these esters to M. persicae was directly proportional to the esterase content of the aphids. Such compounds would not be suitable as commercial insecticides, but the results serve to illustrate the potential benefits of exploiting a resistance mechanism against one class of compounds to render another class more toxic, i.e. to design compounds that show negative cross-resistance. © 1998 SCI     

Detection and spread of Phytophthora austrocedri within infected Juniperus communis woodland and diversity of co‐associated Phytophthoras as revealed by metabarcoding

Phytophthora austrocedri is a recently invasive soilborne pathogen which is causing widespread mortality of Juniperus communis in northern Britain. The pathways by which a single genotype of P. austrocedri has spread to infect such a geographically dispersed range of woodland sites within a relatively short timeframe are unknown. This study examined the detectability of P. austrocedri in soil and water within infected J. communis woodland using qPCR to gain a better understanding of the pathogen's key mechanisms of spread. A Phytophthora metabarcoding method was also applied to investigate the wider diversity of Phytophthora species present in water at one of the sites. qPCR analyses of P. austrocedri in soil samples at a J. communis woodland exhibiting low‐to‐moderate levels of disease suggested a slow natural spread of the pathogen in soil, requiring high moisture conditions. However, the ubiquity of P. austrocedri DNA in soil samples collected across a heavily infected J. communis site suggests that once established at a site the pathogen can be spread readily in soil locally, most likely vectored by animal movements and/or human activities. The hypothesis that P. austrocedri is aerially transmitted in rainwater was not adequately proven, and an alternative hypothesis for the widespread distribution of the pathogen on J. communis in northern Britain is presented. Metabarcoding identified DNA from a diverse range of Phytophthora species in river and rainwater samples although the main target pathogen, P. austrocedri, was not amplified which disagreed with some of the qPCR findings. Possible reasons for this are discussed.     

The Current State of Solar Modeling

Data from the Global Oscillation Network Group (GONG) project and other helioseismic experiments provide a test for models of stellar interiors and for the thermodynamic and radiative properties, on which the models depend, of matter under the extreme conditions found in the sun. Current models are in agreement with the helioseismic inferences, which suggests, for example, that the disagreement between the predicted and observed fluxes of neutrinos from the sun is not caused by errors in the models. However, the GONG data reveal subtle errors in the models, such as an excess in sound speed just beneath the convection zone. These discrepancies indicate effects that have so far not been correctly accounted for; for example, it is plausible that the sound-speed differences reflect weak mixing in stellar interiors, of potential importance to the overall evolution of stars and ultimately to estimates of the age of the galaxy based on stellar evolution calculations.     

Assessing the conservation status of mangroves in Rakhine,Myanmar

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