Photosensitisation diseases of animals: Classification and a weight of evidence approach to primary causes

Clare's (1952) classification system for photosensitisation diseases (types I, II, III and Uncertain) has endured many years of use despite some confusion regarding his secondary, or type III, category, as well as the more recent discovery of two mechanisms (types I and II) of phototoxicity. Therefore, to reduce confusion in terminology, I propose that Clare's four groups be known as primary (or direct), secondary (indirect or hepatogenous), endogenous (aberrant porphyrin synthesis), and idiopathic. The use of the word type can then be reserved for the mechanisms of phototoxicity. Clare's (1952, 1955) papers listed three plants as primary photosensitisers and three as idiopathic. In the literature, several other plants have been associated with photosensitisation in farm animals. Most of these are likely to have a primary pathogenesis; however, the weight of evidence for all but a few is sparse. With respect to plants (and certain mycotoxins and insects) implicated in primary photosensitisation outbreaks, McKenzie's "toxicity confidence rankings" (Australia's Poisonous Plants, Fungi and Cyanobacteria, 2012) has been adapted to "phototoxic agent confidence rankings". Thus, plants, mycotoxins or insects can be categorised regarding phototoxicity, i.e. definite (A); some evidence (B); suspected (C); or phototoxin isolated but no field cases known (D), and weight of evidence, i.e. field cases (1); experimental feeding produces photosensitisation (2); phototoxin isolated (3); phototoxin produces photosensitisation experimentally (4); and/or correlation of the action spectrum/chromatogram in blood or skin with the absorption spectrum/chromatogram of the phototoxin (5). As a result, confidence rankings ranging from A5 to D1 can be allocated. From the available literature, at least seventeen plant species can be ranked as A5 (definite phototoxicity with a maximum weight of evidence). The relatively recent breakthrough regarding the discovery of phototoxic anthraquinones in Heterophyllaea spp. has led to the serendipitous association of the same and similar anthraquinones as the most likely phototoxins in alligator weed (Alternanthera philoxeroides).

Evaluating the use of plant hormones and biostimulators in forage pastures to enhance shoot dry biomass production by perennial ryegrass (Lolium perenne L.)

Fertilisation of established perennial ryegrass forage pastures with nitrogen (N)-based fertilisers is currently the most common practice used on farms to increase pasture forage biomass yield. However, over-fertilisation can lead to undesired environmental impacts, including nitrate leaching into waterways and increased gaseous emissions of ammonia and nitrous oxide to the atmosphere. Additionally, there is growing interest from pastoral farmers to adopt methods for increasing pasture dry matter yield which use 'natural', environmentally safe plant growth stimulators, together with N-based fertilisers. Such plant growth stimulators include plant hormones and plant growth promotive microorganisms such as bacteria and fungi ('biostimulators', which may produce plant growth-inducing hormones), as well as extracts of seaweed (marine algae). This review presents examples and discusses current uses of plant hormones and biostimulators, applied alone or together with N-based fertilisers, to enhance shoot dry matter yield of forage pasture species, with an emphasis on perennial ryegrass.

Impact of mycotoxins and of a mycotoxin deactivator on alpacas grazing perennial ryegrass infected with wild endophyte (Neotyphodium spp.)

Liveweight gain, animal health and the effectiveness of a mycotoxin deactivator were studied on an old pasture that contained 61% perennial ryegrass. Sixty-seven percent of the ryegrass population was infected with endophyte (Neotyphodium spp.). The pasture was fenced into two halves and two groups of 28 alpaca male weaners were rotated between the two plots. Nine to 10 Suris and 18–19 Huacayas were allocated to each group. One group was fed a concentrate supplement (100 g/head per day) and the other was fed the same supplement to which was added the toxin deactivator, Mycofix® Plus (5 g/100 g). Mean liveweight gain on the low-quality pasture over late summer and early autumn was not significantly (P > 0.05) different between the groups. For the control group it was 41 g/day but individual rates of gain ranged from 67 to 0 g/day, depending on the severity of signs of perennial ryegrass toxicosis (r = 0.82, P < 0.001). Liveweight gain was independent of neurotoxic signs in the Mycofix® Plus treated group. Ergovaline concentration in perennial ryegrass varied from 0.43 to a peak in early autumn (March) of 1.05 mg/kg. Mean urine lysergol alkaloid concentration peaked in mid-summer (January) at 109 ng/mg creatinine (control group) and was consistently lower in the Mycofix® Plus group, although the difference approached significance (P = 0.06) only in March. Lolitrem B concentration in perennial ryegrass varied from 0.78 to 1.57 mg/kg. Neurotoxic signs in alpacas were observed throughout the study and peaked in early autumn, coinciding with peak lolitrem B concentration; at this time, 84% of alpacas exhibited neurotoxic signs. Over the 145-day study, the Mycofix® Plus treated group exhibited a lower mean rating of perennial ryegrass toxicosis signs (P < 0.05). Variation in liveweight gain and signs of toxicosis were not associated with significant differences in liver enzyme activity.

Advanced data-mining strategies for the analysis of direct-infusion ion trap mass spectrometry data from the association of perennial ryegrass with its endophytic fungus, Neotyphodium lolii

Direct-infusion mass spectrometry (MS) was applied to study the metabolic effects of the symbiosis between the endophytic fungus Neotyphodium lolii and its host perennial ryegrass (Lolium perenne) in three different tissues (immature leaf, blade, and sheath). Unbiased direct-infusion MS using a linear ion trap mass spectrometer allowed metabolic effects to be determined free of any preconceptions and in a high-throughput fashion. Not only the full MS(1) mass spectra (range 150-1,000 mass-to-charge ratio) were obtained but also MS(2) and MS(3) product ion spectra were collected on the most intense MS(1) ions as described previously (Koulman et al., 2007b). We developed a novel computational methodology to take advantage of the MS(2) product ion spectra collected. Several heterogeneous MS(1) bins (different MS(2) spectra from the same nominal MS(1)) were identified with this method. Exploratory data analysis approaches were also developed to investigate how the metabolome differs in perennial ryegrass infected with N. lolii in comparison to uninfected perennial ryegrass. As well as some known fungal metabolites like peramine and mannitol, several novel metabolites involved in the symbiosis, including putative cyclic oligopeptides, were identified. Correlation network analysis revealed a group of structurally related oligosaccharides, which differed significantly in concentration in perennial ryegrass sheaths due to endophyte infection. This study demonstrates the potential of the combination of unbiased metabolite profiling using ion trap MS and advanced data-mining strategies for discovering unexpected perturbations of the metabolome, and generating new scientific questions for more detailed investigations in the future.

The relationship between mycotoxin synthesis and isolate morphology in fungal endophytes of Lolium perenne

•  Variability in the fungal endophytes of 83 natural populations of Lolium perenne (perennial ryegrass) from Europe was assessed. •  One plant per population was used for endophyte isolation and mycotoxin analysis. Variability in three isozymes, colony morphology and growth rate on potato dextrose agar (PDA), and synthesis of ergovaline, lolitrem B and peramine was recorded. •  Three species were found among 94 strains isolated: Neotyphodium lolii, Neotyphodium sp. (LpTG-2) and Gliocladium-like. The most frequent species was N. lolii, which showed high variability. In 12 populations, a single plant harboured two different endophytes. One-third of the isolates of N. lolii did not produce ergovaline whereas a few isolates did not produce lolitrem B. Ergovaline and lolitrem B-deficient strains, but not the few peramine-deficient isolates, had characteristic morphologies on PDA. No isolate was deficient for both ergovaline and lolitrem B synthesis. •  Selection of ergovaline and lolitrem-deficient strains based only on the morphology of the isolates in culture may be possible.

The lethal principle of Poa huecu (coiron blanco): a plant indigenous to Argentina

The lethality of Poa huecu, a plant toxic to cattle and sheep, was followed by injection of chromatographic fractions in mice. The lethal aqueous extract was administered i.p. to Rockland mice of either sex and produced motor incoordination, transient ataxia, rough hair coat, tremors and muscle contractions and, occasionally, blindness. Doses greater than 1.5 g/kg mouse were always lethal. Fractionation of this lethal extract included dialysis, column chromatography on Sephadex G-25 and fractional precipitation with ethanol. Precipitates obtained with 70% and 85% ethanol were further purified on a DEAE-cellulose column. Eight fractions were obtained, each was injected into mice. Only fractions 3-6 were toxic. Fraction 3 produced slight hepatosis and hyperemia in the liver and gliosis in the brain. None of the other tissues exhibited histological lesions. Fractions 4 and 5 caused death of all animals within 30 min to 4 hr after injection. Polyacrylamide gel electrophoresis and acid hydrolysis showed that fractions 4 and 5 contained a glycoprotein of nearly the same mol. wt (67,000-94,000). Microscopic pathology in the mice treated with the lethal glycoprotein of fraction 4 included hyperemia in the kidneys, megakaryocytes in the spleen, slight hepatosis and focal coagulative necrosis with nuclear pyknosis and karyonexis in the liver, gliosis, intracellular brain edema with axon degeneration and swollen astrocytes in the brain. These brain injuries may relate to the motor incoordination of cattle that causes a delayed righting reflex. The major monosaccharides of the lethal glycoprotein are glucose and mannose, while rhamnose, arabinose, xylose and galactose are present in low percentages. Proline and the acidic amino acids (glutamic and aspartic acids) are the most abundant in the peptidic residue.

[Perloline content in fodder grasses. 1. Quantitative determination of perloline]

A colorimetric method for the quantitative determination of perloline in fodder grasses was established. The comparison with the internationally used spectrofluorimetric method shows that the established method is applicable as a routine method. The average variation coefficient of the colorimetric method is 4.9%. The average rediscovery quota was 95.8% (93.8-99.0%).

The potent tremorgenic neurotoxins lolitrem B and aflatrem: a comparison of the tremor response in mice

Tremor dose-response curves were determined for mice dosed with the ryegrass neurotoxin lolitrem B, and the tremor-genic mycotoxin aflatrem. A family of characteristic curves was revealed for each tremorgenic, with lolitrem B eliciting a sustained tremor response persisting for over 24 h.

Rapid determination of the neurotoxin lolitrem B in perennial ryegrass by high-performance liquid chromatography with fluorescence detection

A rapid, sensitive and quantitative method, based on high-performance liquid chromatography with fluorescence detection, is described for the determination of the neurotoxin lolitrem B in perennial ryegrass, in the ppm to sub-ppm range. The method, which requires a minimal clean-up step prior to chromatographic analysis, is suitable for the routine analysis of large numbers of ryegrass samples, and is currently being used in New Zealand to study the livestock disorder ryegrass staggers. The method is suitable for determining lolitrem B in the whole plant, the seed, and dissected plant components.

Wimmera rye grass toxicity in Western Australia

Outbreaks of Wimmera rye grass toxicity in the south-west of Western Australia, and the associated distribution of Wimmera rye grass parasitised by Anguina sp and Corynebacterium sp were investigated. Between 1970 and 1974, 58 outbreaks occurred on 26 farms in sheep and cattle grazing pasture, cereal crop, stubble, screenings, or hay containing parasitised Wimmera rye grass. Morbidity rates up to 77% were observed. Clinical signs were characterised by staggering, collapse, periods of convulsions and other nervous signs, often followed by death. A pale, friable liver and haemorrhages in different organs were the most constant gross autopsy findings, but no specific histopathological changes were observed. Symptomatic treatment of affected animals and agronomic control measures attempted by farmers were unsuccessful in controlling the disease.

Isolation and separation of tall fescue and ryegrass alkaloids

Bases were extractable from dried, powdered grass material by percolation with methanol. The bases were removed from the methanol by cation-exchange resins and subsequently removed from the resins. Isolation of bases by these methods eliminated the problems associated with the use of large quantities of chlorinated solvents and formation of emulsions found in previously described isolation methods. The bases were separated by paper and thin-layer chromatography (TLC). TLC and a spectrodensitometer were used to quantify the principal alkaloids in crude extracts of tall fescue samples. This procedure recovered all of the alkaloids in spiked samples, and the standard deviation for perlolidine and perloline in tall fescue samples was 3% or less of the mean value.