Sequential administrations of trifluoroacetate induce tolerance to Palicourea maccgravii, a monofluoroacetate-containing plant, in calves

Environmental effects of stratospheric ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 2019

This assessment, by the United Nations Environment Programme (UNEP) Environmental Effects Assessment Panel (EEAP), one of three Panels informing the Parties to the Montreal Protocol, provides an update, since our previous extensive assessment (Photochem. Photobiol. Sci., 2019, 18, 595-828), of recent findings of current and projected interactive environmental effects of ultraviolet (UV) radiation, stratospheric ozone, and climate change. These effects include those on human health, air quality, terrestrial and aquatic ecosystems, biogeochemical cycles, and materials used in construction and other services. The present update evaluates further evidence of the consequences of human activity on climate change that are altering the exposure of organisms and ecosystems to UV radiation. This in turn reveals the interactive effects of many climate change factors with UV radiation that have implications for the atmosphere, feedbacks, contaminant fate and transport, organismal responses, and many outdoor materials including plastics, wood, and fabrics. The universal ratification of the Montreal Protocol, signed by 197 countries, has led to the regulation and phase-out of chemicals that deplete the stratospheric ozone layer. Although this treaty has had unprecedented success in protecting the ozone layer, and hence all life on Earth from damaging UV radiation, it is also making a substantial contribution to reducing climate warming because many of the chemicals under this treaty are greenhouse gases.

Techniques for prevention and control of poisoning by sodium monofluoroacetate (MFA)-containing plants in ruminants

ABSTRACT: Monofluoroacetate (MFA)-containing plants cause sudden death associated with exercise in ruminants, and are responsible for significant losses in Brazilian livestock, estimated at 500,000 bovine deaths annually. Most of the times, the control and treatment of this type of poisoning are not efficient, because disease evolution is superacute, usually causing the death of the animal. Due to the difficulty in controlling this intoxication, several studies have suggested alternatives to prevent it, mainly by making animals resistant to the MFA present in these plants or by avoiding their consumption. This literature review addresses the techniques used experimentally to control the poisoning of ruminants by plants containing MFA. The first studies carried out in Brazil demonstrated that goats and sheep that continuously receive non-toxic doses of plant containing MFA show greater resistance to poisoning than untreated animals, and that this resistance can be transmitted by ruminal fluid transfaunation, suggesting that poisoning occurs due to the presence of bacteria that hydrolyze MFA in the rumen. Based on this hypothesis, several MFA-hydrolyzing bacteria were isolated (Enterococcus faecalis, Bacillus sp., Paenibacillus sp., Burkholderia sp., Cupriavidus sp., Staphylococcus sp., Ancylobacter sp., Ralstonia sp., Stenotrophomonas sp., Pigmentiphaga kullae, and Ancylobacter dichloromethanicus). When some of these bacteria were administered intraruminally, they provided the animal with a different level of protection against poisoning. However, it was observed that protection is gradually lost when the bacterium administration is interrupted. Consequently, to obtain more efficient protection, these bacteria should be administered continuously, probably in the form of probiotics. In another assay, MFA was administered to sheep at non-toxic doses to test the hypothesis that this substance could induce the multiplication of bacteria that hydrolyze it in the rumen. There was no increase in resistance to poisoning after administration of MFA; however, no signs of poisoning were observed when animals received trifluoroacetate and no clinical signs were verified when they were challenged with toxic doses of MFA; in contrast, all control animals presented clinical signs. These results suggest that trifluoroacetate induces the proliferation of MFA-degrading bacteria, and can be used in intoxication prophylaxis. The conditioned food aversion technique, using lithium chloride, has been successfully used experimentally to prevent ruminants from ingesting plants that contain MFA. Another alternative tested was the spraying of Amorimia septentrionalis with the endophytic bacterium Herbaspirillum seropedicae, which degrades MFA, resulting in decreased concentration of this compound in the plants. In conclusion, several experimental techniques have been proved efficient in the control and prophylaxis of MFA-containing plant poisoning; however, none of these techniques are available commercially. Further experiments, mainly in the field, should be carried out to adapt some of these techniques to the conditions of extensive breeding in the numerous areas where MFA-containing plants occur.