WormBase 2007

WormBase (www.wormbase.org) is the major publicly available database of information about Caenorhabditis elegans, an important system for basic biological and biomedical research. Derived from the initial ACeDB database of C. elegans genetic and sequence information, WormBase now includes the genomic, anatomical and functional information about C. elegans, other Caenorhabditis species and other nematodes. As such, it is a crucial resource not only for C. elegans biologists but the larger biomedical and bioinformatics communities. Coverage of core areas of C. elegans biology will allow the biomedical community to make full use of the results of intensive molecular genetic analysis and functional genomic studies of this organism. Improved search and display tools, wider cross-species comparisons and extended ontologies are some of the features that will help scientists extend their research and take advantage of other nematode species genome sequences

Wormwholes: A Commentary On K.F. Schaffer\u27s Genes, Behavior, And Developmental Emergentism

Although Caenorhabditis elegans was chosen and modified to be an organism that would facilitate a reductionist program for neurogenetics, recent research has provided evidence for properties that are emergent from the neurons. While neurogenetic advances have been made using C. elegans which may be useful in explaining human neurobiology, there are severe limitations on C. elegans to explain any significant human behavior

Haematophagic Caenorhabditis elegans

Caenorhabditis elegans is a free-living nematode that resides in soil and typically feeds on bacteria. We postulate that haematophagic C. elegans could provide a model to evaluate vaccine responses to intestinal proteins from hematophagous nematode parasites, such as Necator americanus. Human erythrocytes, fluorescently labelled with tetramethylrhodamine succinimidyl ester, demonstrated a stable bright emission and facilitated visualization of feeding events with fluorescent microscopy. C. elegans were observed feeding on erythrocytes and were shown to rupture red blood cells upon capture to release and ingest their contents. In addition, C. elegans survived equally on a diet of erythrocytes. There was no statistically significant difference in survival when compared with a diet of Escherichia coli OP50. The enzymes responsible for the digestion and detoxification of haem and haemoglobin, which are key components of the hookworm vaccine, were found in the C. elegans intestine. These findings support our postulate that free-living nematodes could provide a model for the assessment of neutralizing antibodies to current and future hematophagous parasite vaccine candidates

Diversification of the Caenorhabditis heat shock response by Helitron transposable elements.

Heat Shock Factor 1 (HSF-1) is a key regulator of the heat shock response (HSR). Upon heat shock, HSF-1 binds well-conserved motifs, called Heat Shock Elements (HSEs), and drives expression of genes important for cellular protection during this stress. Remarkably, we found that substantial numbers of HSEs in multiple Caenorhabditis species reside within Helitrons, a type of DNA transposon. Consistent with Helitron-embedded HSEs being functional, upon heat shock they display increased HSF-1 and RNA polymerase II occupancy and up-regulation of nearby genes in C. elegans. Interestingly, we found that different genes appear to be incorporated into the HSR by species-specific Helitron insertions in C. elegans and C. briggsae and by strain-specific insertions among different wild isolates of C. elegans. Our studies uncover previously unidentified targets of HSF-1 and show that Helitron insertions are responsible for rewiring and diversifying the Caenorhabditis HSR

Intermediary metabolism

Caenorhabditis elegans has orthologs for most of the key enzymes involved in eukaryotic intermediary metabolism, suggesting that the major metabolic pathways are probably present in this species. We discuss how metabolic patterns and activity change as the worm traverses development and ages, or responds to unfavorable external factors, such as temperature extremes or shortages in food or oxygen. Dauer diapause is marked by an enhanced resistance to oxidative stress and a shift toward microaerobic and anaplerotic metabolic pathways and hypometabolism, as indicated by the increased importance of the malate dismutation and glyoxylate pathways and the repression of citric acid cycle activity. These alterations promote prolonged survival of the dauer larva; some of these changes also accompany the extended lifespan of insulin/IGF-1 and several mitochondrial mutants. We also present a brief overview of the nutritional requirements, energy storage and waste products generated by C. elegans

The microbial zoo in the C. elegans intestine: Bacteria, fungi and viruses

Press freedom has become one of the major challenges facing Journalism practice in the world. This paper explores the factors hindering press freedom in Nigeria using some relevant examples. The researcher used the qualitative method of research; using secondary data comprising of books and journals. The study is embedded on social responsibility theory. The study reveals that there are a lot of factors in Nigeria that hinders press freedom ranging from secrecy, legal pressure, direct censorship and force among others. Findings also reveal that Nigerian press freedom is a paradox and only exist on paper i.e. in the constitution but not in practice. The study recommends that since press freedom is granted in the constitution of Nigeria, there should be statutory backup and in order not to hinder press freedom, journalist should be allowed to have access to government sources and records so long as it will not bring chaos to the society at large

Evolution of a polymodal sensory response network

Background: Avoidance of noxious stimuli is essential for the survival of an animal in its natural habitat. Some avoidance responses require polymodal sensory neurons, which sense a range of diverse stimuli, whereas other stimuli require a unimodal sensory neuron, which senses a single stimulus. Polymodality might have evolved to help animals quickly detect and respond to diverse noxious stimuli. Nematodes inhabit diverse habitats and most nematode nervous systems are composed of a small number of neurons, despite a wide assortment in nematode sizes. Given this observation, we speculated that cellular contribution to stereotyped avoidance behaviors would also be conserved between nematode species. The ASH neuron mediates avoidance of three classes of noxious stimuli in Caenorhabditis elegans. Two species of parasitic nematodes also utilize the ASH neuron to avoid certain stimuli. We wanted to extend our knowledge of avoidance behaviors by comparing multiple stimuli in a set of free-living nematode species. Results: We used comparative behavioral analysis and laser microsurgery to examine three avoidance behaviors in six diverse species of free-living nematodes. We found that all species tested exhibit avoidance of chemo-, mechano- and osmosensory stimuli. In C. elegans, the bilaterally symmetric polymodal ASH neurons detect all three classes of repellant. We identified the putative ASH neurons in different nematode species by their anatomical positions and showed that in all six species ablation of the ASH neurons resulted in an inability to avoid noxious stimuli. However, in the nematode Pristionchus pacificus, the ADL neuron in addition to the ASH neuron contributed to osmosensation. In the species Caenorhabditis sp. 3, only the ASH neuron was required to mediate nose touch avoidance instead of three neurons in C. elegans. These data suggest that different species can increase or decrease the contribution of additional, non-ASH sensory neurons mediating osmosensation and mechanosensation. Conclusion: The overall conservation of ASH mediated polymodal nociception suggests that it is an ancestral evolutionarily stable feature of sensation. However, the finding that contribution from non-ASH sensory neurons mediates polymodal nociception in some nematode species suggests that even in conserved sensory behaviors, the cellular response network is dynamic over evolutionary time, perhaps shaped by adaptation of each species to its environment

Lifespan extension in Caenorhabditis elegans insulin/IGF-1 signalling mutants is supported by non-vertebrate physiological traits

The insulin/IGF-1 signalling (IIS) pathway connects nutrient levels to metabolism, growth and lifespan in eukaryotes ranging from yeasts to humans, including nematodes such as the genetic model organism Caenorhabditis elegans. The link between ageing and the IIS pathway has been thoroughly studied in C. elegans; upon reduced IIS signalling, a genetic survival program is activated resulting in a drastic lifespan extension. One of the components of this program is the upregulation of antioxidant activity but experiments failed to show a clear causal relation to longevity. However, oxidative damage, such as protein carbonyls, accumulates at a slower pace in long-lived C. elegans mutants with reduced IIS. This is probably not achieved by increased macroautophagy, a process that sequesters cellular components to be eliminated as protein turnover rates are slowed down in IIS mutants. The IIS mutant daf-2, bearing a mutation in the insulin/IGF-1 receptor, recapitulates the dauer survival program, including accumulation of fat and glycogen. Fat can be converted into glucose and glycogen via the glyoxylate shunt, a pathway absent in vertebrates. These carbohydrates can be used as substrates for trehalose synthesis, also absent in mammals. Trehalose, a non-reducing homodimer of glucose, stabilises intracellular components and is responsible for almost half of the lifespan extension in IIS mutants. Hence, the molecular mechanisms by which lifespan is extended under reduced IIS may differ substantially between phyla that have an active glyoxylate cycle and trehalose synthesis, such as ecdysozoans and fungi, and vertebrate species such as mammals

Caenorhabditis elegans and probiotics interactions from a prolongevity perspective

Probiotics exert beneficial effects on host health through different mechanisms of action, such as production of antimicrobial substances, competition with pathogens, enhancement of host mucosal barrier integrity and immunomodulation. In the context of ageing, which is characterized by several physiological alterations leading to a low grade inflammatory status called inflammageing, evidences suggest a potential prolongevity role of probiotics. Unraveling the mechanisms underlying anti-ageing effects requires the use of simple model systems. To this respect, the nematode Caenorhabditis elegans represents a suitable model organism for the study of both host-microbe interactions and for ageing studies, because of conserved signaling pathways and host defense mechanisms involved in the regulation of its lifespan. Therefore, this review analyses the impact of probiotics on C. elegans age-related parameters, with particular emphasis on oxidative stress, immunity, inflammation and protection from pathogen infections. The picture emerging from our analysis highlights that several probiotic strains are able to exert anti-ageing effects in nematodes by acting on common molecular pathways, such as insulin/insulin-like growth factor-1 (IIS) and p38 mitogen-activated protein kinase (p38 MAPK). In this perspective, C. elegans appears to be advantageous for shedding light on key mechanisms involved in host prolongevity in response to probiotics supplementation