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[
J Exp Biol,
2013]
Gravity on Earth is a constant stimulus and many organisms are able to perceive and respond to it. However, there is no clear evidence that nematodes respond to gravity. In this study, we demonstrated negative gravitaxis in a nematode using dauer larvae (DL) of Caenorhabditis japonica, which form an association with their carrier insect Parastrachia japonensis. Caenorhabditis japonica DL demonstrating nictation, a typical host-finding behavior, had a negative gravitactic behavior, whereas non-nictating C. japonica and C. elegans DL did not. The negative gravitactic index of nictating DL collected from younger nematode cultures was higher than that from older cultures. After a 24 h incubation in M9 buffer, nictating DL did not alter their negative gravitactic behavior, but a longer incubation resulted in less pronounced negative gravitaxis. These results are indicative of negative gravitaxis in nictating C. japonica DL, which is maintained once initiated, seems to be affected by the age of DL and does not appear to be a simple passive mechanism.
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[
Exp Gerontol,
2012]
The nematode dauer larva (DL) is a non-aging diapause stage. The DL of the model nematode Caenorhabditis elegans has been studied as a model system for aging and longevity. However, information on DL in other nematode species is limited. In this study, the survivorship, storage, energy consumption, and oxidative stress tolerance of Caenorhabditis japonica DL were examined. C. japonica is a close relative of C. elegans, but has species-specific phoretic associations with the shield bug Parastrachia japonensis. Also, its DL has a much longer lifespan than C. elegans in a biological setting. However, when C. japonica DLs were detached from their phoretic host, they did not survive more than 10 days while more than 80% of C. elegans survived under the same conditions. Also, C. japonica DL showed more active movement (swimming) and lower tolerance to oxidative stress than C. elegans DL. Because the concentration of triacylglycerol (TAG), the energy source of nematodes, did not decrease significantly during the experiment, exhaustion of the energy reservoir did not cause the low survivorship of C. japonica. Instead, low tolerance to oxidizing stress and increased production of reactive oxygen species in C. japonica were the main causes of the reduced survivorship. The fact that C. japonica DL cannot survive away from its insect host indicates that its longevity is increased by unknown factors derived from the host. Despite these significant differences between C. japonica and C. elegans, these two species are phylogenetically closely related (they are derived from a common ancestor). Therefore, C. japonica could be a good comparative system for C. elegans, and further physiological and molecular analyses of C. japonica DL may provide important information about the internal and external factors affecting the longevity of nematodes in general.
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[
Comparative Biochemistry and Physiology,
1968]
1. Under axenic conditions, the free-living nematodes, Caenorhabditis briggsae, Turbatrix aceti and Panagrellus redivivus, are unable to synthesize cholesterol from acetate-2-C14 or DL-mevalonate-2-C14. 2. No evidence could be found that sterols other than cholesterol are synthesized by any of the organisms.
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[
J Cell Biol,
1993]
The organization of myosin heavy chains (mhc) A and B and paramyosin (pm) which are the major proteins of thick filaments in adult wild-type Caenorhabditis elegans were studied during embryonic development. As a probe of myosin-paramyosin interaction, the
unc-15 mutation
e73 which produces a
glu342lys charge change in pm and leads to the formation of large paracrystalline multi-filament assemblages was compared to wild type. These three proteins colocalized in wild-type embryos from 300 to 550 min of development after first cleavage at 20 degrees C on the basis of immunofluorescence microscopy using specific monoclonal antibodies. Linear structures which were diversely oriented around the muscle cell peripheries appeared at 360 min and became progressively more aligned parallel to the embryonic long axis until distinct myofibrils were formed at 550 min. In the mutant, mhc A and pm were colocalized in the linear structures, but became progressively separated until they showed no spatial overlap at the myofibril stage. These results indicate that the linear structures represent nascent assemblies containing myosin and pm in which the proteins interact differently than in wild-type thick filaments of myofibrils. In
e73, these nascent structures were distinct from the multi-filament assemblages. The overlapping of actin and mhc A in the nascent linear structures suggests their possible structural and functional relationship to the "stress fiber-like structures" of cultured vertebrate muscle cells.
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[
J Cell Biol,
1988]
The thick filaments of the nematode, Caenorhabditis elegans, arising predominantly from the body-wall muscles, contain two myosin isoforms and paramyosin as their major proteins. The two myosins are located in distinct regions of the surfaces, while paramyosin is located within the backbones of the filaments. Tubular structures constitute the cores of the polar regions, and electron-dense material is present in the cores of the central regions (Epstein, H.F., D.M. Miller, I. Ortiz, and G.C. Berliner. 1985. J. Cell Biol. 100:904-915). Biochemical, genetic, and immunological experiments indicate that the two myosins and paramyosin are not necessary core components (Epstein, H.F., I. Ortiz, and L.A. Traeger Mackinnon. 1986. J. Cell Biol. 103:985-993). The existence of the core structures suggests, therefore, that additional proteins may be associated with thick filaments in C. elegans. To biochemically detect minor associated proteins, a new procedure for the isolation of thick filaments of high purity and structural preservation has been developed. The final step, glycerol gradient centrifugation, yielded fractions that are contaminated by, at most, 1-2% with actin, tropomyosin, or ribosome-associated proteins on the basis of Coomassie Blue staining and electron microscopy. Silver staining and radioautography of gel electrophoretograms of unlabeled and 35S-labeled proteins, respectively, revealed at least 10 additional bands that cosedimented with thick filaments in glycerol gradients. Core structures prepared from wild-type thick filaments contained at least six of these thick filament-associated protein bands. The six proteins also cosedimented with thick filaments purified by gradient centrifugation from CB190 mutants lacking myosin heavy chain B and from CB1214 mutants lacking paramyosin. For these reasons, we propose that the six associated proteins are potential candidates for putative components of core structures in the thick filaments of body-wall muscles of C. elegans.
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[
Drug Deliv,
2014]
CONTEXT: In our recent studies, Brugia malayi molecules have shown interesting immune-stimulating and immune-suppressive properties. Among these, F6 a pro-inflammatory (54-68 kDa) SDS-PAGE resolved fraction of the parasite when administered with Freund's complete/incomplete adjuvant in animals, elicited both Th1 and Th2 type immune responses and protects the host from filarial parasite. OBJECTIVE: The present study was aimed at developing biodegradable microspheres for filarial antigenic protein molecules and to investigate the immunoadjuvanticity of microspheres (Ms)-loaded F6 molecules. MATERIALS AND METHODS: Poly-lactide microspheres (DL-PLA-Ms) were prepared using double emulsification and solvent evaporation method; and studied their size, shape, antigen adsorption efficiency, in-process stability, and antigen release profiles. F6 and B. malayi adult worm (BmA: 17 to 180 kDa) protein molecules adsorbed on the Ms were administered in a single shot into Swiss mice, subcutaneously, and investigated their immunoadjuvant effect and compared with one/two doses-schedule of plain F6/BmA. RESULTS: Immunization with F6/BmA-loaded DL-PLA-Ms resulted in upregulation of cellular proliferation, IFN- , TNF- and NO release from host's cells stimulated with F6/BmA or LPS/Con A, IgG, IgG1 and IgG2a levels. These responses were well comparable with the responses produced by two doses of plain BmA/F6. DISCUSSION AND CONCLUSION: In conclusion, a single dose of DL-PLA-Ms-F6 induced predominantly Th1 immune responses and well comparable with two doses of plain F6. This is the first ever report on potential of DL-PLA-Ms as adjuvant for filarial immunogen.
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[
MicroPubl Biol,
2021]
Fic domain-containing AMPylases (Fic AMPylases) are a family of evolutionarily conserved enzymes present in most metazoans. Fic AMPylases are bi-functional: as monomers, these enzymes catalyze the transfer of AMP at the expense of an ATP molecule to surface-exposed threonine and serine hydroxyl groups (target AMPylation) (Chatterjee and Truttmann, 2021; Perera et al., 2019); upon dimerization and co-factor exchange, the same catalytic site supports AMP removal from modified proteins (target deAMPylation) (Casey et al., 2018; Moehlman et al., 2018; Preissler et al., 2017a; Preissler et al., 2017b; Veyron et al., 2019). Work by many groups suggests that fic AMPylases modify proteins in the endoplasmic reticulum (ER) as well as in the cytoplasm, with a preference for the ER-resident chaperone BiP/Grp78 (Fig. 1A). The activity of fic AMPylases is tightly regulated. Fic AMPylase-mediated hyper-AMPylation, achieved by the over-expression of constitutive AMPylase mutants, is toxic and leads to cell death in human in cellulo models (Sanyal et al., 2015), as well as Saccharomyces cerevisiae (Truttmann et al., 2017), Drosophila melanogaster (Casey et al., 2018) and Caenorhabditis elegans (Truttmann et al., 2018) in vivo models. Hyper-AMPylation-mediated cell death involves caspase-dependent apoptotic signaling (Sanyal et al., 2015). However, a detailed understanding as to why hyper-AMPylation is lethal remains elusive. One major hypothesis in the field is that hyper-AMPylation will deplete cellular ATP pools, leading to starvation-induced apoptosis.
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[
MicroPubl Biol,
2021]
Reproductive adults and developmentally arrested larvae often occupy different ecological niches and thus are expected to respond differently to environmental stimuli. To understand the genes that coordinate dauer development and olfactory behavior, we examined adult and dauer C. elegans in wild-type and dauer constitutive mutants (Daf-c). We found all dauers showed decreased attraction to all three odorants tested compared to adults, with
daf-7 dauer larva (DL) exhibiting a concentration-dependent preference shift towards isoamyl alcohol, suggesting that the TGF- pathway is involved in both dauer regulation and dauer-specific odortaxis.
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[
BioData Min,
2021]
BACKGROUND: The data explosion caused by unprecedented advancements in the field of genomics is constantly challenging the conventional methods used in the interpretation of the human genome. The demand for robust algorithms over the recent years has brought huge success in the field of Deep Learning (DL) in solving many difficult tasks in image, speech and natural language processing by automating the manual process of architecture design. This has been fueled through the development of new DL architectures. Yet genomics possesses unique challenges that requires customization and development of new DL models. METHODS: We proposed a new model, DASSI, by adapting a differential architecture search method and applying it to the Splice Site (SS) recognition task on DNA sequences to discover new high-performance convolutional architectures in an automated manner. We evaluated the discovered model against state-of-the-art tools to classify true and false SS in Homo sapiens (Human), Arabidopsis thaliana (Plant), Caenorhabditis elegans (Worm) and Drosophila melanogaster (Fly). RESULTS: Our experimental evaluation demonstrated that the discovered architecture outperformed baseline models and fixed architectures and showed competitive results against state-of-the-art models used in classification of splice sites. The proposed model - DASSI has a compact architecture and showed very good results on a transfer learning task. The benchmarking experiments of execution time and precision on architecture search and evaluation process showed better performance on recently available GPUs making it feasible to adopt architecture search based methods on large datasets. CONCLUSIONS: We proposed the use of differential architecture search method (DASSI) to perform SS classification on raw DNA sequences, and discovered new neural network models with low number of tunable parameters and competitive performance compared with manually engineered architectures. We have extensively benchmarked DASSI model with other state-of-the-art models and assessed its computational efficiency. The results have shown a high potential of using automated architecture search mechanism for solving various problems in the field of genomics.
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[
Nematologica,
1977]
The quantitative sterol requirements were studied in C. briggsae, C. elegans (Be), C. elegans (Br), and T. aceti. It was shown that all four nematodes had similar minimal sterol requirements (0.1-2.0 ug/ml) and toxicity appeared in T. aceti at 50 ug/ml. Cholesterol and five precursors were tested for population growth. We found that acetic acid, DL-mevalonic acid lactone, and farnesol did not support population growth; while squalene, lanosterol, and cholesterol supported significant population growth in all four nematodes. Our results suggest that the major metabolic block in the pathway of sterol biosynthesis occurs between the step of farnesol and squalene.