A fluorescent investigation of subcellular damage in H9c2 cells caused by pavetamine, a novel polyamine

Food, Feed and Veterinary Public Health Programme, Agricultural Research Council-Onderstepoort Veterinary Institute, Private Bag X5, Onderstepoort 0110, South Africa.
Toxicology in Vitro (Impact Factor: 2.9). 02/2010; 24(4):1258-65. DOI: 10.1016/j.tiv.2010.02.002
Source: PubMed


Gousiekte, which can be translated literally as "quick disease", is one of the six most important plant toxicoses that affect livestock in South Africa. It is a plant-induced cardiomyopathy of domestic ruminants characterised by the sudden death of animals within a period of 4-8weeks after the initial ingestion of the toxic plant. The main ultrastructural change in sheep hearts is degradation of myofibres. In this study, fluorescent probes were used to investigate subcellular changes induced by pavetamine, the toxic compound that causes gousiekte, in H9c2 cells. The sarcoplasmic reticula (SR) and mitochondria showed abnormalities that were not present in the control cells. The lysosomes of treated cells were more abundant and enlarged than those of the control cells. There was increased activity of cytosolic hexosaminidase and acid phosphatase, indicating increased lysosomal membrane permeability. Lysosomes play an important role in both necrosis and apoptosis. The degradation of the myofibres may be a consequence of the increased lysosomal membrane permeability. Pavetamine was also found to cause alterations in the organisation of F-actin. F-actin in the nucleus is a transcription regulator and can therefore influence protein synthesis. Actin filament organisation also regulates the cardiac L-type Ca(2+) channels. Fluorescent staining demonstrated that pavetamine may damage a number of organelles, all of which can influence the proper functioning of the heart.

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    • "Hitherto research into gousiekte was primarily carried out by veterinarians and focused on the aetiology and pathology of the disease. More recently toxicologists and chemists showed interest in the disease resulting in the isolation and chemical characterization of pavettamine, the compound claimed to be the cause of the cardiotoxicosis [2]–[4]. Gousiekte is a disease of ruminants characterized by acute heart failure without early warning signs 4–8 weeks after the initial ingestion of certain bacteriophilous Rubiaceae. "
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    ABSTRACT: South African plant species of the genera Fadogia, Pavetta and Vangueria (all belonging to Rubiaceae) are known to cause gousiekte (literally 'quick disease'), a fatal cardiotoxicosis of ruminants characterised by acute heart failure four to eight weeks after ingestion. Noteworthy is that all these plants harbour endophytes in their leaves: nodulating bacteria in specialized nodules in Pavetta and non-nodulating bacteria in the intercellular spaces between mesophyll cells in Fadogia and Vangueria. Isolation and analyses of these endophytes reveal the presence of Burkholderia bacteria in all the plant species implicated in gousiekte. Although the nodulating and non-nodulating bacteria belong to the same genus, they are phylogenetically not closely related and even fall in different bacterial clades. Pavetta harborii and Pavetta schumanniana have their own specific endophyte--Candidatus Burkholderia harborii and Candidatus Burkholderia schumanniana--while the non-nodulating bacteria found in the other gousiekte-inducing plants show high similarity to Burkholderia caledonica. In this group, the bacteria are host specific at population level. Investigation of gousiekte-inducing plants from other African countries resulted in the discovery of the same endophytes. Several other plants of the genera Afrocanthium, Canthium, Keetia, Psydrax, Pygmaeothamnus and Pyrostria were tested and were found to lack bacterial endophytes. The discovery and identification of Burkholderia bacteria in gousiekte-inducing plants open new perspectives and opportunities for research not only into the cause of this economically important disease, but also into the evolution and functional significance of bacterial endosymbiosis in Rubiaceae. Other South African Rubiaceae that grow in the same area as the gousiekte-inducing plants were found to lack bacterial endophytes which suggests a link between bacteria and gousiekte. The same bacteria are consistently found in gousiekte-inducing plants from different regions indicating that these plants will also be toxic to ruminants in other African countries.
    PLoS ONE 06/2011; 6(4):e19265. DOI:10.1371/journal.pone.0019265 · 3.23 Impact Factor
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    ABSTRACT: Fadogia homblei, Pavetta harborii, Pavetta schumanniana, Vangueria pygmaea (=Pachystigma pygmaeum), Vangueria latifolia (=Pachystigma latifolium) and Vangueria thamnus (=Pachystigma thamnus) all induce one of the most important cardiotoxicoses of domestic ruminants in southern Africa, causing the sickness gousiekte. All the plants which cause gousiekte have previously been shown to contain bacterial endophytes. However, in this study other plants within the Vanguerieae tribe that have not been reported to cause gousiekte; namely Vangueria infausta, Vangueria macrocalyx and Vangueria madagascariensis, have now been shown to also contain endophytes within the inter-cellular spaces of the leaves. The disease gousiekte is difficult to characterise due to fluctuations in plant toxicity. The majority of reported cases of gousiekte poisoning are at the beginning of the growing season; and thus the plants are thought to be more toxic at this time. By using both transmission and scanning electron microscopy the endophytes within these Vanguerieae plants were compared visually. Using the plant reported most often for gousiekte poisoning, V. pygmaea, a basic seasonal comparison of the presence of endophytes was done. It was found that the bacterial endophyte colonies were most abundant during the spring season.
    South African Journal of Botany 05/2013; 86:41-45. DOI:10.1016/j.sajb.2013.01.007 · 0.98 Impact Factor

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