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  1. Effects of simulated microgravity on gene expression and biological phenotypes of a single generation Caenorhabditis elegans cultured on 2 different media
    Tee LF, Neoh HM, Then SM, Murad NA, Asillam MF, Hashim MH, et al.
    Life Sci Space Res (Amst), 2017 Nov;15:11-17.
    PMID: 29198309 DOI: 10.1016/j.lssr.2017.06.002
    Studies of multigenerational Caenorhabditis elegans exposed to long-term spaceflight have revealed expression changes of genes involved in longevity, DNA repair, and locomotion. However, results from spaceflight experiments are difficult to reproduce as space missions are costly and opportunities are rather limited for researchers. In addition, multigenerational cultures of C. elegans used in previous studies contribute to mixture of gene expression profiles from both larvae and adult worms, which were recently reported to be different. Usage of different culture media during microgravity simulation experiments might also give rise to differences in the gene expression and biological phenotypes of the worms. In this study, we investigated the effects of simulated microgravity on the gene expression and biological phenotype profiles of a single generation of C. elegans worms cultured on 2 different culture media. A desktop Random Positioning Machine (RPM) was used to simulate microgravity on the worms for approximately 52 to 54 h. Gene expression profile was analysed using the Affymetrix GeneChip® C. elegans 1.0 ST Array. Only one gene (R01H2.2) was found to be downregulated in nematode growth medium (NGM)-cultured worms exposed to simulated microgravity. On the other hand, eight genes were differentially expressed for C. elegans Maintenance Medium (CeMM)-cultured worms in microgravity; six were upregulated, while two were downregulated. Five of the upregulated genes (C07E3.15, C34H3.21, C32D5.16, F35H8.9 and C34F11.17) encode non-coding RNAs. In terms of biological phenotype, we observed that microgravity-simulated worms experienced minimal changes in terms of lifespan, locomotion and reproductive capabilities in comparison with the ground controls. Taking it all together, simulated microgravity on a single generation of C. elegans did not confer major changes to their gene expression and biological phenotype. Nevertheless, exposure of the worms to microgravity lead to higher expression of non-coding RNA genes, which may play an epigenetic role in the worms during longer terms of microgravity exposure.
    Matched MeSH terms: Caenorhabditis elegans/physiology
  2. Fulltext Effect of the tocotrienol-rich fraction on the lifespan and oxidative biomarkers in Caenorhabditis elegans under oxidative stress
    Aan GJ, Zainudin MS, Karim NA, Ngah WZ
    Clinics (Sao Paulo), 2013 May;68(5):599-604.
    PMID: 23778402 DOI: 10.6061/clinics/2013(05)04
    OBJECTIVE: This study was performed to determine the effect of the tocotrienol-rich fraction on the lifespan and oxidative status of C. elegans under oxidative stress.

    METHOD: Lifespan was determined by counting the number of surviving nematodes daily under a dissecting microscope after treatment with hydrogen peroxide and the tocotrienol-rich fraction. The evaluated oxidative markers included lipofuscin, which was measured using a fluorescent microscope, and protein carbonyl and 8-hydroxy-2'-deoxyguanosine, which were measured using commercially available kits.

    RESULTS: Hydrogen peroxide-induced oxidative stress significantly decreased the mean lifespan of C. elegans, which was restored to that of the control by the tocotrienol-rich fraction when administered before or both before and after the hydrogen peroxide. The accumulation of the age marker lipofuscin, which increased with hydrogen peroxide exposure, was decreased with upon treatment with the tocotrienol-rich fraction (p<0.05). The level of 8-hydroxy-2'-deoxyguanosine significantly increased in the hydrogen peroxide-induced group relative to the control. Treatment with the tocotrienol-rich fraction before or after hydrogen peroxide induction also increased the level of 8-hydroxy-2'-deoxyguanosine relative to the control. However, neither hydrogen peroxide nor the tocotrienol-rich fraction treatment affected the protein carbonyl content of the nematodes.

    CONCLUSION: The tocotrienol-rich fraction restored the lifespan of oxidative stress-induced C. elegans and reduced the accumulation of lipofuscin but did not affect protein damage. In addition, DNA oxidation was increased.

    Matched MeSH terms: Caenorhabditis elegans/physiology
  3. Pathogenicity and phenotypic analysis of sopB, sopD and pipD virulence factors in Salmonella enterica serovar typhimurium and Salmonella enterica serovar Agona
    Khoo CH, Sim JH, Salleh NA, Cheah YK
    Antonie Van Leeuwenhoek, 2015 Jan;107(1):23-37.
    PMID: 25312847 DOI: 10.1007/s10482-014-0300-7
    Salmonella is an important food-borne pathogen causing disease in humans and animals worldwide. Salmonellosis may be caused by any one of over 2,500 serovars of Salmonella. Nonetheless, Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Agona are the second most prevalent serovars isolated from humans and livestock products respectively. Limited knowledge is available about the virulence mechanisms responsible for diarrheal disease caused by them. To investigate the contribution of sopB, sopD and pipD as virulence factors in intracellular infections and the uniqueness of these bacteria becoming far more prevalent than other serovars, the infection model of Caenorhabditis elegans and phenotypic microarray were used to characterize their mutants. The strains containing the mutation in sopB, sopD and pipD genes were constructed by using latest site-specific group II intron mutagenesis approach to reveal the pathogenicity of the virulence factors. Overall, we observed that the mutations in sopB, sopD and pipD genes of both serovars did not exhibit significant decrease in virulence towards the nematode. This may indicate that these virulence effectors may not be universal virulence factors involved in conserved innate immunity. There are significant phenotypic differences amongst strains carrying sopB, sopD and pipD gene mutations via the analysis of biochemical profiles of the bacteria. Interestingly, mutant strains displayed different susceptibility to chemical stressors from several distinct pharmacological and structural classes when compared to its isogenic parental strains. These metabolic and chemosensitivity assays also revealed multiple roles of Salmonella virulence factors in nutrient metabolism and antibiotic resistance.
    Matched MeSH terms: Caenorhabditis elegans/physiology
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