Volatile organic compounds (VOC) as biomarkers for detection of Ceratocystis platani

Ceratocystis platani causes canker stain of plane trees, and it represents a serious disease of Platanus spp. both in the United States and Europe. Current chemical or biological controls do not effectively manage C. platani, so new preventive methods need to be developed in order to limit this pathogen spreading. In this work, we have characterized the main volatile organic compounds (VOC) emitted in vitro from pure cultures of C. platani and other common pathogenic fungal species of hosts plants growing in the same ecosystems as plane trees. We found that C. platani emitted a similar blend of VOC compared with phylogenetically similar species C. populicola. In particular, C. platani was characterized by emission of isoamyl acetate and isobutyl acetate while C. populicola by ethyl acetate and isobutyl acetate, which were not released by any of the other out‐group fungal species grown on the same medium. Moreover, following a targeted approach based on the main VOC found in vitro, we have successfully validated in vivo that VOC uniquely emitted by C. platani (i.e. isobutyl acetate along with isoamyl alcohol) were released from the bark of plane trees following C. platani inoculation. Our results highlight the possibility to exploit VOC emitted specifically by C. platani as biomarkers to recognize Platanus x acerifolia plants infected by this pathogen.     

Ovine toxoplasmosis: Seroconversion during pregnancy and lamb birth rate in Uruguayan sheep flocks

Specific anti-Toxoplasma gondii antibodies were analyzed by latex agglutination during the 5 months of pregnancy in the serum of sheep from two flocks in the Uruguayan north-west: one flock (79 sheep) kept under an intensive management system and the other (494 sheep) kept under an extensive management system. Titers obtained using the latex test correlated with those obtained by indirect immunofluorescence. Pregnancy was confirmed by laparoscopy in all sheep from the smaller flock and by determination of serum progesterone levels in the seroconverted sheep from the larger flock. The percentage of sheep originally exhibiting significant serum levels of anti-T. gondii anti-bodies (13.9% in the smaller flock and 28.5% in the larger one) as well as the observed levels of seroconversion (22.8% and 7.7%, respectively), indicated a high prevalence of this infection in the north-west of Uruguay. In addition, birth rates of seroconverted sheep in the larger flock were significantly different from those of non-seroconverted animals. These results, although preliminary, suggest that Toxoplasma infection would produce considerable economic losses in extensive ovine production in Uruguay.     

Ectoparasite control.

The severity of damage that insects, ticks, and mites may have on their bovine hosts ranges from undetectable effects on energy expenditure to the death of the host. These pest insects can cause direct damage to their hosts by their annoyance, irritation, blood feeding, modification of host behavior, and invasion of tissues. This direct damage can result in such direct losses as dermatitis, anemia,reduction in weight gain performance, devaluation of carcass,injury during pest avoidance, injury by chemical control of pests,necrosis, and death. The main flies that affect cattle performance and specifically, stockers, are discussed in this article.     

Water-use efficiency in cork oak (Quercus suber) is modified by the interaction of water and light availabilities

We studied the interaction of light and water on water-use efficiency in cork oak (Quercus suber L.) seedlings. One-year-old cork oak seedlings were grown in pots in a factorial experiment with four light treatments (68, 50, 15 and 5% of full sunlight) and two irrigation regimes: well watered (WW) and moderate drought stress (WS). Leaf predawn water potential, which was measured at the end of each of two cycles, did not differ among the light treatments. Water-use efficiency, assessed by carbon isotope composition (delta(13)C), tended to increase with increasing irradiance. The trend was similar in the WW and WS treatments, though with lower delta(13)C in all light treatments in the WW irrigation regime. Specific leaf area increased with decreasing irradiance, and was inversely correlated with delta(13)C. Thus, changes in delta(13)C could be explained in part by light-induced modifications in leaf morphology. The relationship between stomatal conductance to water vapor and net photosynthesis on a leaf area basis confirmed that seedlings in higher irradiances maintained a higher rate of carbon uptake at a particular stomatal conductance, implying that shaded seedlings have a lower water-use efficiency that is unrelated to water availability.     

Effects of Dietary Protein Source and Feeding Regime on Growth Performance,Nutrient Digestibility,Fatty Acids,and Quality Characteristics of Rainbow Trout,Oncorhynchus mykiss,Fillets

This study investigated the effects of dietary protein source and feeding regime (apparent satiation and rationed) on growth performance, nutrient digestibility, fatty acid (FA) profile, and fillet quality traits in rainbow trout. A stock of 1200 juvenile trout (mean weight 114.6 ± 0.2 g) were randomly distributed into 24 fiberglass tanks (four diets × three replications × two feeding regimes). The experimental diets were formulated to be isoproteic and isoenergetic based on bacterial protein meal (BPM), pea protein concentrate (PPC), mixture thereof (MIX), and fish meal (FM), respectively. The feeding trial lasted 77 d with water temperature of 13 C. Statistical differences appeared among the diets only in terms of crude protein digestibility. Growth performance and somatic indexes were significantly affected by the diet, while only the condition factor was influenced by the feeding regime. None of the parameters appeared to be affected by the interaction effects. Differences appeared between the FA profiles of the dorsal muscle. Oleic, linoleic, α‐linolenic, and docosahexaenoic acid contents were influenced by diet, while only minor FAs were influenced by feeding regime. In conclusion, growth performance and nutrient digestibility resulted lower in fish fed BPM diet than other groups, while PPC group was similar to FM group.