Dose response of sheep poisoned with locoweed (Oxytropis sericea)

Lisosomal storage disease caused by ingestion of Astragalus spp in llamas: an emergent concern

Lysosomal storage diseases are inherited or acquired disorders characterized by dysfunctional lysosomes that lead to intracytoplasmic accumulation of undegraded substrates, causing impaired cellular function and death. Many acquired lysosomal storage diseases are produced by toxic plants, which have indolizidine alkaloids, including swainsonine, that inhibits lysosomal α-mannosidase and Golgi α-mannosidase II. Swainsonine-induced nervous disease associated with various plants has been reported, including species of the genus Astragalus, Sida, Oxitropis, Swainsona, and Ipomoea. Two species of Astragalus (i.e. Astragalus garbancillo and Astragalus punae) have been found to cause neurologic disease in llamas. In addition, A. garbancillo was also associated with malformations in the offspring, and possibly abortions and neonatal mortality in llamas. The diagnosis of Astragalus spp. intoxication is established based on clinical signs, microscopic and ultrastructural findings, lectin histochemistry, abundance of these plants in the grazing area and determination of swainsonine in plant specimens.

Toxicological evaluation of microbial secondary metabolites in the context of European active substance approval for plant protection products

Risk assessment (RA) of microbial secondary metabolites (SM) is part of the EU approval process for microbial active substances (AS) used in plant protection products (PPP). As the number of potentially produced microbial SM may be high for a certain microbial strain and existing information on the metabolites often are low, data gaps are frequently identified during the RA. Often, RA cannot conclusively clarify the toxicological relevance of the individual substances. This work presents data and RA conclusions on four metabolites, Beauvericin, 2,3-deepoxy-2,3-didehydro-rhizoxin (DDR), Leucinostatin A and Swainsonin in detail as examples for the challenging process of RA. To overcome the problem of incomplete assessment reports, RA of microbial AS for PPP is in need of new approaches. In view of the Next Generation Risk Assessment (NGRA), the combination of literature data, omic-methods, in vitro and in silico methods combined in adverse outcome pathways (AOPs) can be used for an efficient and targeted identification and assessment of metabolites of concern (MoC).

Microbial pesticides - challenges and future perspectives for testing and safety assessment with respect to human health

Plant protection measures are necessary to prevent pests and diseases from attacking and destroying crop plants and to meet consumer demands for agricultural produce. In the last decades the use of chemical pesticides has largely increased. Farmers are looking for alternatives. Biopesticides should be considered a sustainable solution. They may be less toxic than chemical pesticides, be very specific to the target pest, decompose quickly, and be less likely to cause resistance. On the other hand, lower efficacy and higher costs are two disadvantages of many biopesticides. Biopesticides include macroorganisms, natural compounds and microorganisms. Microbial pesticides are the most widely used and studied class of biopesticides. The greatest difference between microbial and chemical pesticides is the ability of the former to potentially multiply in the environment and on the crop plant after application. The data requirements for the European Union and the United States Environmental Protection Agency are highlighted, as these regulatory processes are the most followed in regions where local regulations for biopesticide products are not available or vague. New Approach Methods already proposed or harmonized for chemical pesticides are presented and discussed with respect to their use in evaluating microbial pesticide formulations. Evaluating the microbials themselves is not as simple as using the same validated New Approach Methods as for synthetic pesticides. Therefore, the authors suggest considering New Approach Method strategies specifically for microbials and global harmonization with acceptability with the advancements of such approaches. Further discussion is needed and greatly appreciated by the experts.

Alternaria gansuense, a Plant Systematic Fungal Pathogen Producing Swainsonine in Vivo and in Vitro

Astragalus adsurgens (A. adsurgens), which is considered a forage in China, grows widely in Eurasia and North America. However, Alternaria gansuense (A. gansuense) (synonym: Embellisia astragali) systematically infects A. adsurgens, producing swainsonine (SW), which poisons domesticated animals. In this study, we hypothesized that the A. gansuense SW-producing fungus is morphologically and molecularly related to the locoweed endophyte, Alternaria oxytropis (A. oxytropis), which systematically grows in host plants. Therefore, pure cultures of the fungi from diseased plants or endophytic interactions were collected from fields and assayed for SW via high-performance liquid chromatography linked to mass spectroscopy (HPLC-MS). The production of SW was also detected in A. adsurgens, A. oxytropis and diseased plants by assaying for the presence of the β-ketoacyl synthase (KS) gene, which is required for SW synthesis. Diseased A. adsurgens and pure cultures of A. gansuense have SW and the healthy-looking A. adsurgens plants also contained SW, probably because they were infected with A. gansuense. Therefore, A. adsurgens-infected A. gansuense are not safe for livestock consumption.

Biomarkers and their potential for detecting livestock plant poisonings in Western North America

The United States National Cancer Institute defines a biomarker as: "A biological molecule found in blood, other body fluids, or tissues that is a sign of a normal or abnormal process, or of a condition or disease." In Veterinary Medicine, biomarkers associated with plant poisonings of livestock have great utility. Since grazing livestock poisoned by toxic plants are often found dead, biomarkers of plant poisoning allow for a more rapid postmortem diagnosis and response to prevent further deaths. The presence and concentration of toxins in poisonous plants are biomarkers of risk for livestock poisoning that can be measured by the chemical analysis of plant material. More difficult is, the detection of plant toxins or biomarkers in biological samples from intoxicated or deceased animals. The purpose of this article is to review potential biomarkers of plant poisoning in grazing livestock in the Western North America including recently investigated non-invasive sampling techniques. Plants discussed include larkspur, lupine, water hemlock, swainsonine-containing plants, selenium-containing plants, and pyrrolizidine alkaloid containing plants. Other factors such as animal age and sex that affect plant biomarker concentrations in vivo are also discussed.

Intoxication of llamas by Astragalus punae in Argentina

Several plants that contain indolizidine alkaloids, including swainsonine, are toxic to livestock, causing dysfunctional lysosomes and storage disease. Swainsonine induces a neurovisceral disease, known as locoism, in sheep, goats, and cattle, which occurs in several parts of the world, including, but not limited to, the western United States, China, and parts of Australia. In South America, locoism has been described in the Andean region of Argentina affecting sheep, cattle, and llamas. Intoxication by consumption of Astragalus punae was suspected in 4 llamas in Jujuy Province, northwestern Argentina. The grazing area contained abundant specimens of A. punae. The clinical course was ~15 d, and included moderate ataxia, incoordination of hindlimbs, and progressive loss of body condition. Microscopically, fine cytoplasmic microvacuolation was observed in the proximal convoluted renal tubules. Ultrastructurally, these changes consisted of severely dilated lysosomes. Swainsonine was detected in stem and leaf samples of A. punae at a concentration of 0.06%. Based on clinical history and signs, histologic and ultrastructural changes, and plant analysis, a diagnosis of swainsonine toxicosis caused by consumption of A. punae was made, which has not been reported previously, to our knowledge.

Alpha-mannosidosis caused by toxic plants in ruminants of Argentina

It is well known that several of the swainsonine-containing plant species found widespread around the world have a negative economic impact in each country. In Argentina, most of the information on the poisonous plant species that produce α-mannosidosis is published in Spanish and thus not available to most English-speaking researchers interested in toxic plants. Therefore, the aim of this review is to summarize the information about swainsonine-containing plants in Argentina, which are extensively distributed throughout different ecoregions of the country. To date, five species from three genera have been shown to induce α-mannosidosis in livestock in Argentina: Ipomoea carnea subsp. fistulosa, Ipomoea hieronymi subsp. calchaquina (Convolvulaceae), Astragalus garbancillo, Astragalus pehuenches (Fabaceae), and Sida rodrigoi (Malvaceae). These species contain the indolizidine alkaloid swainsonine, which inhibits the lysosomal enzyme α-mannosidase and consequently affects glycoprotein metabolism, resulting in partially metabolized sugars. The prolonged consumption of these poisonous plants produces progressive weight loss and clinical signs related to a nervous disorder, characterized by tremors of head and neck, abnormalities of gait, difficulty in standing, ataxia and wide-based stance. Histological lesions are mainly characterized by vacuolation of different cells, especially neurons of the central nervous system. The main animal model used to study α-mannosidosis is the guinea pig because, when experimentally poisoned, it exhibits many of the characteristics of naturally intoxicated livestock.

Toxicity of the swainsonine-containing plant Ipomoea carnea subsp. fistulosa for goats and sheep

In order to determine the toxicity of swainsonine present in Ipomoea carnea for goats and sheep, 12 goats and 12 sheep were divided into 3 groups of 4 goats (G1, G2 and G3) and 3 groups of 4 sheep (S4, S5 and S6) each. Groups G1 and S4 were used as controls; G2 and S5 received 1 mg/kg body weight of swainsonine from plant material and G3 and S6 received 3 mg/kg. Groups G2 and G3 presented the first clinical signs, on average, after the 54th and 39th days of ingestion of the plant, respectively. Groups S5 and S6 presented the first clinical signs, on average, on the 64th and 42nd days of the experiment, respectively. In sheep, in addition to having a longer period of ingestion until the onset of clinical signs, these signs were less severe, being evident only after the animals were forced to move. These results demonstrated that goats are more susceptible to swainsonine poisoning than sheep. Complete regression of clinical signs was observed in 5 goats and 6 sheep. However, three goats and one sheep remained with clinical signs until 120 days of the experiment, suggesting that to control the poisoning the animals should be removed from the pastures immediately after the first clinical signs. There were no significant differences in weight between the different groups, suggesting that for goats ingesting the plant, toxic Ipomoea species can be used as forage for intermittent periods of 15-30 days.

Intoxication by Astragalus garbancillo var. garbancillo in llamas

Lysosomal storage diseases are inherited and acquired disorders characterized by dysfunctional lysosomes. Intracytoplasmic accumulation of undegraded substrates leads to impaired cellular function and death. Several plant species are toxic to livestock because of the presence of indolizidine alkaloids, including swainsonine, which cause a storage disease. Swainsonine-induced nervous disease (i.e., locoism) of sheep and cattle is well recognized in several parts of the world, particularly in the western United States and in parts of Australia. Spontaneous intoxication by Astragalus garbancillo var. garbancillo was suspected in a group of 70 llamas (Lama glama) in Jujuy Province, northwestern Argentina. The animals grazed an area dominated by stands of A. garbancillo var. garbancillo. Clinical signs were staggering, ataxia, hypermetria, and progressive weight loss. The clinical course in individual animals was ~50 d. The main microscopic changes were Purkinje cell degeneration, necrosis, and loss, associated with intracytoplasmic vacuolation, meganeurite formation, and Wallerian degeneration. Specific positive labeling for ubiquitin was observed in axonal spheroids. Composite leaf and stem samples of A. garbancillo var. garbancillo analyzed by high-performance liquid chromatography contained 0.03% swainsonine. Based on the microscopic lesions, clinical history, and plant analysis, a diagnosis was made of storage disease caused by consumption of swainsonine-containing A. garbancillo var. garbancillo.

Clinical and pathological comparison of Astragalus lentiginosus and Ipomoea carnea poisoning in goats

The indolizidine alkaloid swainsonine, found in some Astragalus and Oxytropis (i.e., locoweed) species, is a potent cellular glycosidase inhibitor that often poisons livestock. Other toxic genera such as some Ipomoea species also contain swainsonine as well as calystegines which are similar polyhydroxy alkaloids. The toxicity of calystegines is poorly characterized; however, they are also potent glycoside inhibitors capable of intestinal and cellular glycoside dysfunction. The objective of this study was to directly compare A. lentiginosus and I. carnea poisoning in goats to better characterize the role of the calystegines. Three groups of four goats each were treated with ground alfalfa (control), I. carnea or A. lentiginosus to obtain daily doses of 0.0, 1.5, and 1.5 mg swainsonine/kg bw per day, respectively, for 45 days. Animals were observed daily and weekly body weights, serum enzyme activities, and serum swainsonine concentrations were determined. At day 45 all animals were euthanized and necropsied. Goats treated with A. lentiginosus and I. carnea developed clinical disease characterized by mild intention tremors and proprioceptive deficits. Goats treated with A. lentiginosus developed clinical disease sooner and with greater consistency. No differences in body weight, serum swainsonine concentrations and serum enzyme activity were observed between goats treated with A. lentiginosus and I. carnea. Additionally, there were no differences in the microscopic and histochemical studies of the visceral and neurologic lesions observed between goats treated with A. lentiginosus and I. carnea. These findings suggest that I. carnea-induced clinical signs and lesions are due to swainsonine and that calystegines contribute little or nothing to toxicity in goats in the presence of swainsonine.

Maternal exposure to swainsonine impaired the early postnatal development of mouse dentate gyrus of offspring

Neurogenesis in the dentate gyrus (DG) plays a key role in the normal of structure and function of the hippocampus-learning and memory. After eating the locoweeds, animals develop a chronic neurological disease called "locoism". Swainsonine (SW) is the main toxin in locoweeds. Studies have shown that SW induces neuronal apoptosis in vitro and impairs learning and memory in adult mouse. The present study explored effects of SW exposure to dams on the postnatal neurogenesis of DG of offspring. Pregnant ICR mice were orally gavaged with SW at a dose of 0, 5.6 or 8.4 mg/kg/day from gestation day 10 to postnatal day (PND) 21, respectively. We found that SW impaired the proliferation capacity of neural progenitor cells in the DG so that the number of newborn cells was reduced at PND 8. Using the postnatal in vivo electroporation, we showed that the dendritic branching and total length of granule cells were significantly decreased due to SW exposure. In addition, on PND 21, the density of NeuN-positive and Reelin-positive interneurons increased in the hilus, implying the disorder of neuronal migration. These results suggest that maternal exposure to SW, the neurogenesis of DG on offspring was disrupted, finally leading to the functional disorder of DG.

Inhibiting gustatory thalamus or medial amygdala has opposing effects on taste neophobia

Taste neophobia is a feeding system defense mechanism that limits consumption of an unknown, and therefore potentially dangerous, edible until the post-ingestive consequences are experienced. We found that transient pharmacological inhibition (induced with the GABA agonists baclofen and muscimol) of the gustatory thalamus (GT; Experiment 1), but not medial amygdala (MeA; Experiment 2), during exposure to a novel saccharin solution attenuated taste neophobia. In Experiment 3 we found that inhibition of MeA neurons (induced with the chemogenetic receptor hM4DGi) enhanced the expression of taste neophobia whereas excitation of MeA neurons (with hM3DGq) had no influence of taste neophobia. Overall, these results refine the temporal involvement of the GT in the occurrence of taste neophobia and support the hypothesis that neuronal excitation in the GT is necessary for taste neophobia. Conversely, we show that chemogenetically, but not pharmacologically, inhibiting MeA neurons is sufficient to exaggerate the expression of taste neophobia.

Characterisation of the circulating acellular proteome of healthy sheep using LC-MS/MS-based proteomics analysis of serum

BACKGROUND

Unlike humans, there is currently no publicly available reference mass spectrometry-based circulating acellular proteome data for sheep, limiting the analysis and interpretation of a range of physiological changes and disease states. The objective of this study was to develop a robust and comprehensive method to characterise the circulating acellular proteome in ovine serum.

METHODS

Serum samples from healthy sheep were subjected to shotgun proteomic analysis using nano liquid chromatography nano electrospray ionisation tandem mass spectrometry (nanoLC-nanoESI-MS/MS) on a quadrupole time-of-flight instrument (TripleTOF® 5600+, SCIEX). Proteins were identified using ProteinPilot™ (SCIEX) and Mascot (Matrix Science) software based on a minimum of two unmodified highly scoring unique peptides per protein at a false discovery rate (FDR) of 1% software by searching a subset of the Universal Protein Resource Knowledgebase (UniProtKB) database (http://www.uniprot.org). PeptideShaker (CompOmics, VIB-UGent) searches were used to validate protein identifications from ProteinPilot™ and Mascot.

RESULTS

ProteinPilot™ and Mascot identified 245 and 379 protein groups (IDs), respectively, and PeptideShaker validated 133 protein IDs from the entire dataset. Since Mascot software is considered the industry standard and identified the most proteins, these were analysed using the Protein ANalysis THrough Evolutionary Relationships (PANTHER) classification tool revealing the association of 349 genes with 127 protein pathway hits. These data are available via ProteomeXchange with identifier PXD004989.

CONCLUSIONS

These results demonstrated for the first time the feasibility of characterising the ovine circulating acellular proteome using nanoLC-nanoESI-MS/MS. This peptide spectral data contributes to a protein library that can be used to identify a wide range of proteins in ovine serum.

A survey of swainsonine content in Swainsona species

The indolizidine alkaloid swainsonine is an inhibitor of α-mannosidase and mannosidase II that causes lysosomal storage disease and alters glycoprotein processing. Several plant species worldwide contain swainsonine, grazing these plants may cause severe toxicosis in livestock, leading to a chronic disease characterised by altered behaviour, depression, weight loss, decreased libido, infertility and death. Swainsona is a large genus of the Fabaceae family with all species but one being endemic to Australia. Swainsonine has previously been reported to be, or expected to be, present in 26 Swainsona species in Australia. Methods of detection in these 26 species were a jack bean α-mannosidase inhibition assay, gas chromatography, or gas or liquid chromatography coupled with mass spectrometry. Seven of these 26 Swainsona species are reported to be toxic, and for three of these no chemical assay for swainsonine has been undertaken. Only 1 of the 26 species has been analysed for swainsonine using modern instrumentation such as gas or liquid chromatography coupled with mass spectrometry. Using both liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry, 248 specimens representing 41 Swainsona species were screened in the present study for swainsonine. Swainsonine was detected in 9 of the 41 Swainsona species, eight of which had not been determined to contain swainsonine previously using modern instrumentation. The list of swainsonine-containing taxa reported here will serve as a reference for diagnostic purposes and risk assessment.

Locoweed (Oxytropis sericea)—induced Lesions in Mule Deer (Odocoileius hemionus)

Locoweed poisoning has been reported in wildlife, but it is unknown whether mule deer ( Odocoileius hemionus)are susceptible. In areas that are heavily infested with locoweed, deer and elk ( Cervus elaphus nelsoni)have developed a spongiform encephalopathy, chronic wasting disease (CWD). Although these are distinct diseases, no good comparisons are available. The purpose of this study was to induce and describe chronic locoweed poisoning in deer and compare it with the lesions of CWD. Two groups of four mule deer were fed either a complete pelleted ration or a similar ration containing 15% locoweed ( Oxytropis sericea). Poisoned deer lost weight and developed a scruffy, dull coat. They developed reluctance to move, and movement produced subtle intention tremors. Poisoned deer had extensive vacuolation of visceral tissues, which was most severe in the exocrine pancreas. Thyroid follicular epithelium, renal tubular epithelium, and macrophages in many tissues were mildly vacuolated. The exposed deer also had mild neuronal swelling and cytoplasmic vacuolation that was most obvious in Purkinje cells. Axonal swelling and dystrophy was found in many white tracts, but it was most severe in the cerebellar peduncles and the gracilis and cuneate fasciculi. These findings indicate that deer are susceptible to locoweed poisoning, but the lesions differ in severity and distribution from those of other species. The histologic changes of locoweed poisoning are distinct from those of CWD in deer; however, the clinical presentation of locoweed poisoning in deer is similar. Histologic and immunohistochemical studies are required for a definitive diagnosis.

Pathogenesis and preventive treatment for animal disease due to locoweed poisoning

Locoweeds are perennial herbaceous plants included in Astragalus spp. and Oxytropis spp. that contain the toxic indolizidine alkaloid swainsonine. The livestock that consume locoweed feeding can suffer from a type of toxicity called "locoism." There are aliphatic nitro compounds, selenium, selenium compounds and alkaloids in locoweed. The toxic component in locoweeds has been identified as swainsonine, an indolizidine alkaloid. Swainsonine inhibits lysosomal α-mannosidase and mannosidase II, resulting in altered oligosaccharide degradation and incomplete glycoprotein processing. As a result, livestock that consume locoweeds exhibit several symptoms, including dispirited behavior, staggering gait, chromatopsia, trembling, ataxia, and cellular vacuolar degeneration of most tissues by pathological observation. Locoism results in significant annual economic losses. Recently, locoweed populations have increased domestically in China and abroad, resulting in an increase in the incidence of poisoning. Therefore, in this paper, we review the current research on locoweed, including on species variation, pathogenesis, damage and poisoning prevention measures.

Poisonous plants: effects on embryo and fetal development

Poisonous plant research in the United States began over 100 years ago as a result of livestock losses from toxic plants as settlers migrated westward with their flocks, herds, and families. Major losses were soon associated with poisonous plants, such as locoweeds, selenium accumulating plants, poison-hemlock, larkspurs, Veratrum, lupines, death camas, water hemlock, and others. Identification of plants associated with poisoning, chemistry of the plants, physiological effects, pathology, diagnosis, and prognosis, why animals eat the plants, and grazing management to mitigate losses became the overarching mission of the current Poisonous Plant Research Laboratory. Additionally, spin-off benefits resulting from the animal research have provided novel compounds, new techniques, and animal models to study human health conditions (biomedical research). The Poisonous Plant Research Laboratory has become an international leader of poisonous plant research as evidenced by the recent completion of the ninth International Symposium on Poisonous Plant Research held July 2013 in Hohhot, Inner Mongolia, China. In this article, we review plants that negatively impact embryo/fetal and neonatal growth and development, with emphasis on those plants that cause birth defects. Although this article focuses on the general aspects of selected groups of plants and their effects on the developing offspring, a companion paper in this volume reviews current understanding of the physiological, biochemical, and molecular mechanisms of toxicoses and teratogenesis.

Potential degradation of swainsonine by intracellular enzymes of Arthrobacter sp. HW08

Swainsonine (SW) is a toxin produced by locoweeds and harmful to the livestock industry. Degrading SW by Arthrobacter sp. HW08 was demonstrated as a promising way to deal with SW poisoning. However, it is unknown which part of the subcellular enzymes in Arthrobacter sp. HW08 is responsible for biodegrading SW and whether the metabolites are atoxic. In this study, intracellular and extracellular enzymes of Arthrobacter sp. HW08 were isolated and their enzyme activity was evaluated. The metabolites were fed to mice, and physiological and histological properties of the treated mice were investigated. The results showed that only intracellular enzyme of Arthrobacter sp. HW08 (IEHW08) could degrade SW efficiently. Compared with mice in SW treatment group, mice in SW + IEHW08 treatment group (1) increased their body weights; (2) showed higher number of platelets and lower number of white blood cells; (3) decreased the levels of creatinine, urea nitrogen, alanine transaminase and aspartate aminotransferase in serum; (4) reduced the number of vacuolated cells in cerebellum, liver and kidney. All these data demonstrate that IEHW08 was potentially safe for mice, while keeping the capacity of degrading SW. This study indicates a possible application of IEHW08 as an additive in the livestock industry to protect animals from SW poisoning.

Locoweed dose responses to nitrogen: Positive for biomass and primary physiology, but inconsistent for an alkaloid

PREMISE OF THE STUDY

Plant communities may be influenced by toxic secondary metabolites or enhanced plant growth from plant-symbiont interactions. The C:N hypothesis predicts that carbon or nitrogen constrains plant secondary metabolite production, but it does not consider compounds produced by plant symbionts. Locoweeds are legumes that can have fungal endophyte alkaloid (swainsonine [SWA]) production, which causes livestock poisoning. We studied four locoweed taxa to test whether average SWA concentrations influenced SWA positive dose responses to N fertilizer.

METHODS

We measured locoweed leaf SWA, pigment concentrations and photosynthetic activity, and plant biomass dose responses to N supplementation for 3 mo in two greenhouse experiments.

KEY RESULTS

Leaf photosynthesis, leaf pigment concentrations, and plant biomass had positive, unsaturated dose responses across tested N doses. Although N enhanced primary growth, two moderate-SWA taxa (Astragalus mollissimus var. bigelovii and Oxytropis sericea) had negative SWA dose responses to increasing N, the high-SWA taxon (A. moll. var. mollissimus) had no SWA change, and the very low-SWA taxon (A. moll. var. matthewsii) had a transient positive dose response.

CONCLUSIONS

Supplemented N led to positive dose responses for plant biomass and leaf photosynthesis and pigments, but SWA dose responses differed across locoweed taxa and time. At N levels that enhanced plant growth and reduced antioxidant protective systems, fungal endophyte alkaloid production was not strongly influenced. Production of SWA may be more strongly influenced by factors other than C:N supply (e.g., seasonality, plant age) in the locoweed-endophyte-Rhizobium complex.

Toxins and adverse drug reactions affecting the equine nervous system

This article provides an overview of the more common toxins and adverse drug reactions, along with more rare toxins and reactions (Table 1), that result in neurologic dysfunction in horses. A wide variety of symptoms, treatments, and outcomes are seen with toxic neurologic disease in horses. An in-depth history and thorough physical examination are needed to determine if a toxin or adverse drug reaction is responsible for the clinical signs. Once a toxin or adverse drug reaction is identified, the specific antidote, if available, and supportive care should be administered promptly.

Encefalopatia hereditária em bovinos no estado do Espírito Santo

Descrevem-se os aspectos epidemiológicos e clínico-necroscópicos de uma doença neurológica hereditária observada em bovinos no município de Ecoporanga, norte do Estado do Espírito Santo. Trata-se de enfermidade do sistema nervoso central verificada exclusivamente em fêmeas, filhas de touro reprodutor de 5 anos de idade da raça Nelore, oriundo do município de Curvelo, Minas Gerais, com vacas mestiças Nelore x Quianini; bezerros machos oriundos deste cruzamento não demonstraram quaisquer sinais relacionados à enfermidade. Os sinais clínicos, presentes ao nascimento ou detectáveis nas primeiras semanas de vida, caracterizam-se por ataxia, perda do equilíbrio, instabilidade, andar em círculos, posicionamento incorreto dos membros no animal em estação ou em marcha (afastamento e/ou desvio de membros da posição normal) e desvio lateral da coluna (eixo principal do corpo em diagonal). De animal para animal, há marcada variação na intensidade das manifestações clínicas. Os bovinos mais afetados morrem devido à incapacidade de se alimentar. O exame macroscópico evidenciou, em grau variável de intensidade, áreas de depressão assimétrica setorial, sobretudo nos lobos frontal e temporal do córtex telencefálico e no córtex cerebelar. Em adição observou-se atrofia de grupos musculares de membros correspondentes às porções defeituosas no sistema nervoso central. O estudo histológico inicial revelou que as áreas deprimidas devem-se à redução setorial de populações neuronais (provavelmente abiotrofia/atrofia) principalmente nos lobos cerebrais frontal e temporal e nas camadas granular e molecular do córtex cerebelar. Estudos morfométrico, imunohistoquímico e ultraestrutural estão sendo realizados e devem trazer mais informações sobre os aspectos microscópicos e patogenéticos. Os achados epidemiológicos indicam que a enfermidade está diretamente ligada ao cromossoma X, com penetrância completa e expressividade variável.

Swainsonine and endophyte relationships in Astragalus mollissimus and Astragalus lentiginosus

Locoweeds are defined as Astragalus and Oxytropis species that induce locoism due to the toxic alkaloid swainsonine. Swainsonine was detected in all parts of Astragalus lentiginosus and Astragalus mollissimus , with greater concentrations found in the aboveground parts. Undifilum oxytropis , a fungal endophyte responsible for the synthesis of swainsonine, was detected in all plant parts of A. lentiginosus and A. mollissimus. The amount of endophyte within a plant part does not always correspond to the concentration of swainsonine in the same part. Plants of A. mollissimus and A. lentiginosus can be divided into two chemotypes: those that contain swainsonine (>0.1%; chemotype 1) and those that contain little or no detectable swainsonine (<0.01%; chemotype 2). Chemotype 1 plants in both species had quantitatively higher amounts of endophyte compared to chemotype 2 plants. Swainsonine and endophyte amounts were not uniformly distributed within stalks of the same plant. For that reason, repeated sampling of stalks from the same plant during one growing season may provide misleading results. Sequence variants of U. oxytropis exist within populations of A. mollissimus, A. lentiginosus, and Oxytropis sericea and do not correlate with chemotype. These findings suggest several possible reasons for differential concentrations of swainsonine that will be tested in future work.

Development of a transformation system in the swainsonine producing, slow growing endophytic fungus, Undifilum oxytropis

Undifilum oxytropis (Phylum: Ascomycota; Family: Pleosporaceae) is a slow growing endophytic fungus that produces a toxic alkaloid, swainsonine. This endophyte resides in locoweeds, which are perennial flowering legumes. Consumption of this fungus by grazing animals induces a neurological disorder called locoism. The alkaloid swainsonine, an alpha-mannosidase inhibitor, is responsible for the field toxicity related to locoism. Little is known about the biosynthetic pathway of swainsonine in endophytic fungi. Genetic manipulation of endophytic fungi is important to better understand biochemical pathways involved in alkaloid synthesis, but no transformation system has been available for studying such enzymes in Undifilum. In this study we report the development of protoplast and transformation system for U. oxytropis. Fungal mycelia required for generating protoplasts were grown in liquid culture, then harvested and processed with various enzymes. Protoplasts were transformed with a fungal specific vector driving the expression of Enhanced Green Florescent Protein (EGFP). The quality of transformed protoplasts and transformation efficiency were monitored during the process. In all cases, resistance to antibiotic hygromycin B was maintained. Such manipulation will open avenues for future research to decipher fungal metabolic pathways.

Relationship between the endophyte Embellisia spp. and the toxic alkaloid swainsonine in major locoweed species (Astragalus and Oxytropis)

Locoweeds (Astragalus and Oxytropis spp. that contain the toxic alkaloid swainsonine) cause widespread poisoning of livestock on western rangelands. There are 354 species of Astragalus and 22 species of Oxytropis in the US and Canada. Recently, a fungal endophyte, Embellisia spp., was isolated from Astragalus and Oxytropis spp. and shown to produce swainsonine. We conducted a survey of the major locoweeds from areas where locoweed poisoning has occurred to verify the presence of the endophyte and to relate endophyte infection with swainsonine concentrations. Species found to contain the fungal endophyte and produce substantial amounts of swainsonine were A. wootoni, A. pubentissimus, A. mollissimus, A. lentiginosus, and O. sericea. Astragalus species generally had higher concentrations of swainsonine than Oxytropis. Swainsonine was not detected in A. alpinus, A. cibarius, A. coltonii, A. filipes, or O. campestris. The endophyte could not be cultured from A. mollissimus var. thompsonii or A. amphioxys, but was detected by polymerase chain reaction, and only 30% of these samples contained trace levels of swainsonine. Further research is necessary to determine if the endophyte is able to colonize these and other species of Astragalus and Oxytropis and determine environmental influences on its growth and synthesis of swainsonine.

Intoxicação experimental por Sida carpinifolia (Malvaceae) em ovinos

Administrou-se Sida carpinifolia L.f. secada à sombra e moída, em doses diárias de 11 a 30g/kg/dia, para sete ovinos. Um animal foi encontrado morto aos 18 e outro morreu apresentando sinais clínicos aos 53 dias do início do experimento. Outros quatro animais adoeceram e foram eutanasiados aos 30, 45, 75 e 100 dias do experimento. O fornecimento de S. carpinifolia foi interrompido em um ovino ao 80º dia do experimento, e o animal foi eutanasiado 70 dias após. Todos os animais foram necropsiados. O consumo variou entre 11 e 30 g/kg/dia da planta seca. As principais alterações clínicas iniciaram a partir do 20º dia com emaciação progressiva e leve diarréia. Os sinais neurológicos iniciaram no 25º dia e eram caracterizados por ataxia com dismetria, tremores da cabeça, posturas atípicas, quedas freqüentes, lentidão dos movimentos, dificuldade em apreender e deglutir os alimentos. Esses sinais clínicos se acentuavam quando os animais eram forçados a se movimentar. O ovino que parou de consumir Sida carpinifolia, recuperou-se clinicamente e 11 dias após a interrupção não apresentava mais alterações clínicas. Na necropsia havia aumento de volume dos linfonodos mesentéricos em cinco dos sete ovinos. Ao exame histológico as alterações mais significativas estavam presentes no sistema nervoso central e constavam de distensão e vacuolização citoplasmáticas afetando principalmente as células de Purkinje do cerebelo, os neurônios do córtex cerebral, do tálamo, do mesencéfalo e dos cornos ventrais da medula espinhal. Também foram observados esferóides axonais mais freqüentes na camada granular do cerebelo. A vacuolização citoplasmática foi observada também no epitélio dos ácinos pancreáticos e dos túbulos renais, nas células foliculares da tireóide, nos hepatócitos e macrófagos de órgãos linfóides. As lesões ultra-estruturais observadas foram vacuolizações citoplasmáticas, algumas envoltas por membranas, em neurônios de Purkinje do cerebelo e nas células foliculares da tireóide. O ovino que permaneceu 70 dias sem consumir S. carpinifolia não apresentou alterações histológicas.

Effects of locoweed on serum swainsonine and selected serum constituents in sheep during acute and subacute oral/intraruminal exposure1

A study was conducted to evaluate the effects of acute and subacute locoweed exposure on serum swainsonine concentrations and selected serum constituents in sheep. Thirteen mixed-breed wethers (BW = 47.5 +/- 9.3 kg) were assigned randomly to 0.2, 0.4, or 0.8 mg of swainsonine x kg BW(-1) x d(-1) treatments. During acute (24 h) and subacute (19 d) exposure, serum swainsonine was detected in all treatments and was greatest (P < 0.03) in the 0.8 mg treatment. Serum alkaline phosphate (ALK-P) activity was increased (P < 0.01) for the 0.8 mg treatment compared with baseline (0 h) by 7 h and continued to increase throughout the initial 22 h following acute exposure to locoweed. A linear increase (P < 0.01) in serum ALK-P activity was noted, with the rate being 3.00 +/- 0.56 U x L(-1) x h(-1). Serum ALK-P activity was increased (P < 0.05) across treatments on d 7 over d -19, -12, 0, 1, 21, and 26; on d 14 over d -19, -12, 0, and 26; and on d 19 over d -19, -12, 0, 1, 21, and 26. By d 20, approximately 48 h after last exposure to swainsonine, serum ALK-P activities were no longer different (P = 0.13) than baseline (d -19, -12, and 0), and by d 26 values had generally returned to baseline. No linear (P = 0.98), quadratic (P = 0.63), or cubic effects of swainsonine with time from exposure were noted for serum aspartate aminotransferase. Similar to serum ALK-P activities, serum aspartate aminotransferase activities were increased (P < 0.05) across treatment levels on d 7, 14, 19, 20, 21, and 26 over those on d -19, -12, 0, and 1. Total serum Fe was decreased (P < 0.05) within the initial 22 h following the swainsonine exposure. On d 21 (48 h after swainsonine feeding ended), serum Fe increased to 472 mg/L. Concentrations of ceruloplasmin were lower (P < 0.10) on d 14 and 19 following exposure to locoweed. Recovery of ceruloplasmin levels coincided with similar changes in serum Fe. There was a linear (slope = 0.33 mg x dL(-1) x d(-1); P < 0.01) effect with time of exposure to locoweed (i.e., swainsonine) on serum triglyceride concentrations. Rapid changes in serum ALK-P and Fe concentrations without parallel changes in other damage markers indicate that acute exposure to swainsonine induces metabolic changes that may impair animal production and health before events of cytotoxicity thought to induce clinical manifestation of locoism.

Analysis of swainsonine: extraction methods, detection, and measurement in populations of locoweeds (Oxytropis spp.)

An analytical method has been developed to measure the locoweed toxin, swainsonine, in locoweed plant material. Dry ground plant samples were extracted using a small-scale liquid/liquid extraction procedure followed by isolation of the swainsonine by solid phase extraction with a cation-exchange resin. Detection and quantitation of the swainsonine were accomplished using reversed phase high-performance liquid chromatography coupled to atmospheric pressure chemical ionization tandem mass spectrometry (LC-MS(2)). The limit of quantitation was estimated to be 0.001% swainsonine by weight in dry plant material, which corresponds to the lower threshold for toxicity of locoweeds. The method of analysis was applied to the analysis of Oxytropis sericea (white locoweed) and Oxytropis lambertii (Lambert locoweed) plant samples to measure the variability of individual plant swainsonine levels within populations and within species. Individual plant variability was found to be highly significant for both O. sericea and O. lambertii populations. The combined three-year mean swainsonine values taken from three populations of O. sericea ranged from 0.046% in Utah to 0.097% in a New Mexico population. Sixteen individual populations of O. lambertii were sampled from eight different U.S. states. Swainsonine was detected at levels >0.001% in only 5 of the 16 collection sites. Those populations of O. lambertii found to contain higher swainsonine levels were restricted to the most southern and western portion of its distribution, and all were identified as belonging to var. bigelovii, whereas var. articulata and var. lambertii samples contained swainsonine at levels <0.001%.