Aeromonas
Dongyou Liu in Laboratory Models for Foodborne Infections, 2017
Tetrahymena spp. (T. thermophila and T. pyriformis) are freshwater free-living ciliate protozoa that grow readily in culture media between 12°C and 41°C without a CO2-enriched atmosphere, and thus offer an economical and permissive model to evaluate the virulence is aquatic Aeromonas isolates. Aeromonas isolate is considered virulent when relative survival is >60%, whereas Aeromonas isolate is considered avirulent when relative survival is <40%. Similarly, Aeromonas isolate is regarded as virulent when relative survival of T. thermophila is >40% after coculture with Aeromonas, whereas Aeromonas isolate is classified as avirulent when relative survival of T. thermophila is >50% after coculture with Aeromonas [57]. In addition, highly virulent Aeromonas strains grow well in T. thermophila, causing deformation to and even lysis of T. thermophila, whereas avirulent Aeromonas strains are largely phagocytozed by T. thermophila, causing no obvious damage to T. thermophila [59].
Structural and Biochemical Studies of the Dynein ATPase
Claude Gagnon in Controls of Sperm Motility, 2020
The use of ATP analogs such as 8-azido ATP demonstrated that the heavy chains are indeed the site of ATP binding and hydrolysis.16,17 Polypeptide analysis of isolated dyneins from a variety of sources shows a remarkable degree of similarity as well as some significant differences. In all cases, the number of heavy chain polypeptides above 350 kDa (named α, β, and 7, in order of increasing mobility on SDS-PAGE) equals the number of globular heads observed. Thus, dynein obtained from Tetrahymena1 and Chlamydomonas13 each have three heavy chains and three globular heads, whereas sea urchin,14 bull sperm,3 porcine tracheal cilia,4 and MAP 1C18 each have two heavy chains and two globular heads. The numbers of intermediate chains and light chains are a bit more difficult to determine since some of these lighter chains may, in fact, be proteolytic breakdown products of heavier chains. Detailed analysis of the intermediate and light chains in Chlamydomonas show the presence of two intermediate chains with molecular weights of 78 kDa and 69 kDa and up to ten light chains.19Tetrahymena has been reported to have three intermediate chains with molecular weights of 70, 85, and 100,1 and at least four immunologically dissimilar light chains.44
rDNA: Evolution Over a Billion Years
S. K. Dutta in DNA Systematics, 2019
Comparisons of IVSs which insert in the 28S rRNA gene have been made for certain Tetrahymena species and these introns seem to be good phylogenetic probes for at least species level comparisons and possibly familial comparisons in Drosophila. Tetrahymena thermophila and T. pigmentosa are 93% homologous out of the 413 nucleotides sequenced for the IVS.76 The types of changes between the two intervening sequences are found to be basepair substitutions (8 transitions, 14 transversions), and the 5′ end was more conserved than the 3′ end. Barnett and Rae,277 using melting point analysis, indicated that the IVS of D. virilis and D. melanogaster differ in size, but share considerable sequence homologies even with more distantly related dipterans such as Sarcophaga and Musca (both of which are in the same suborder as the Drosophila species).
Development of reliable quantitative structure–toxicity relationship models for toxicity prediction of benzene derivatives using semiempirical descriptors
Published in Toxicology Mechanisms and Methods, 2023
Ayushi Singh, Sunil Kumar, Archana Kapoor, Parvin Kumar, Ashwani Kumar
Invertebrates and algae are the important testing endpoint for chemical safety assessment and in silico predictive methods are required to fill the data gap of toxicity toward toxicity endpoints (EC–European Commission Regulation 1999; ECHA. 2008; Valerio 2012). Algae form one of the most significant parts of the food chain of the aquatic environment and are responsible for providing basic nutrition to aquatic organisms. Bioaccumulation of chemicals by algae leads to biomagnification which can cause toxicity to other living organisms including human beings (Seth and Roy 2020). Therefore, it is important to develop predictive models for toxicity toward algae like Scenedesmus obliquus. Its rapid reproduction ability and high sensitivity to pollutants make it an attractive model organism for environmental toxicity determination (Cai et al. 2008). Likewise, Ciliated protozoa, e.g. Tetrahymena pyriformis possess many characteristics which are desirable in a test organism for assessment of environmental risk, e.g. it occurs at the first tropic level and shows early indications of toxicity. It is significantly involved in energy and matter transfer and can be cultured easily. These models can be used to study physiological and metabolic processes for several generations which is very important from a toxicology point of view (Bogaerts et al. 2001).
Predicting skin sensitization potential of organic compounds based on toxicity enhancement to Tetrahymena pyriformis, fathead minnow, and Daphnia magna
Published in Journal of Immunotoxicology, 2018
Weicheng Zhang, Libao Chen, Lunguang Yao
Toxicity enhancement (Te), previously termed excess toxicity, is widely used to determine whether a compound can elicit reactive toxicity through a comparison with its baseline toxicity (von der Ohe et al. 2005; Schramm et al. 2011). Te = 10 has been proposed as a threshold to discriminate reactive from non-reactive compounds. Similarly, one reasonably assumes that toxicity enhancement can be utilized to discriminate a sensitizer from a non-sensitizer. In the present study, data on the toxicity of 65 compounds to Tetrahymena pyriformis, fathead minnow, and Daphnia magna were compiled and collected, and toxicity enhancements of each in the three biosystems were calculated and applied to predict their sensitization potency. The three selected assays in the different species, toxic endpoints, and exposure durations demonstrated that toxicity enhancement was a reliable parameter that could be used to predict skin sensitization potency and discriminate strong (and extreme) and moderate sensitizers from weak and non-sensitizers.
Ion channels as therapeutic antibody targets
Published in mAbs, 2019
Catherine J. Hutchings, Paul Colussi, Theodore G. Clark
Cilated protozoa devote a large part of their metabolism towards membrane protein production and have expanded gene families for all four of the major classes of membrane transporters, including P-type ATPases, major facilitator superfamily members, ABC transporters and voltage-gated ion channels.75Tetrahymena thermophila, in particular, has been identified as an attractive platform for over-expression of recombinant human ion channels based on the fact that its macronuclear genome encodes approximately three times as many voltage-dependent K+ channels as do human cells.75 Although a complex eukaryote, Tetrahymena shares many of the features of microbial expression hosts, including ease of growth in peptone-based media at scale with relatively short doubling times of 2 to 3 hours.76
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