Transcriptional response of Caenorhabditis elegans when exposed to Shigella flexneri.

In recent years, researchers have begun to use Caenorhabditis elegans as a potential animal model to study Shigella pathogenesis. This study aims to further develop this model using RNA-sequencing to understand which pathways/cellular characteristics are affected and potentially cause death in Shigella-exposed worms. We identified 1631 differentially expressed genes in Shigella-exposed worms (6 h exposure).

Functions of Flavonoids in Plant⁻Nematode Interactions.

Most land plants can become infected by plant parasitic nematodes in the field. Plant parasitic nematodes can be free-living or endoparasitic, and they usually infect plant roots. Most damaging are endoparasites, which form feeding sites inside plant roots that damage the root system and redirect nutrients towards the parasite.

Shigella flexneri infection in Caenorhabditis elegans: cytopathological examination and identification of host responses.

The Gram-negative bacterium Shigella flexneri is the causative agent of shigellosis, a diarrhoeal disease also known as bacillary dysentery. S. flexneri infects the colonic and rectal epithelia of its primate host and induces a cascade of inflammatory responses that culminates in the destruction of the host intestinal lining.

The periplasmic enzyme, AnsB, of Shigella flexneri modulates bacterial adherence to host epithelial cells.

S. flexneri strains, most frequently linked with endemic outbreaks of shigellosis, invade the colonic and rectal epithelium of their host and cause severe tissue damage. Here we have attempted to elucidate the contribution of the periplasmic enzyme, L-asparaginase (AnsB) to the pathogenesis of S.

C. elegans RNA-dependent RNA polymerases rrf-1 and ego-1 silence Drosophila transgenes by differing mechanisms.

Drosophila possesses the core gene silencing machinery but, like all insects, lacks the canonical RNA-dependent RNA polymerases (RdRps) that in C. elegans either trigger or enhance two major small RNA-dependent gene silencing pathways. Introduction of two different nematode RdRps into Drosophila showed them to be functional, resulting in differing silencing activities.

VHA-19 is essential in Caenorhabditis elegans oocytes for embryogenesis and is involved in trafficking in oocytes.

There is an urgent need to develop new drugs against parasitic nematodes, which are a significant burden on human health and agriculture. Information about the function of essential nematode-specific genes provides insight to key nematode-specific processes that could be targeted with drugs. We have characterized the function of a novel, nematode-specific Caenorhabditis elegans protein, VHA-19, and show that VHA-19 is essential in the germline and, specifically, the oocytes, for the completion of embryogenesis.

Differential gene expression at coral settlement and metamorphosis--a subtractive hybridization study.

Background: A successful metamorphosis from a planktonic larva to a settled polyp, which under favorable conditions will establish a future colony, is critical for the survival of corals. However, in contrast to the situation in other animals, e.g.

Minireview: the role of the vacuolar ATPase in nematodes.

The vacuolar ATPase enzyme complex (V-ATPase) pumps protons across membranes, energised by hydrolysis of ATP. It is involved in many physiological processes and has been implicated in many different diseases. While the broader functions of V-ATPases have been reviewed extensively, the role of this complex in nematodes specifically has not.

Hosts use altered macronutrient intake to circumvent parasite-induced reduction in fecundity.

Explanations for the evolution of pathogen-induced fecundity reduction usually rely on a common principle: the trade-off between host longevity and reproduction. Recent advances in nutritional research have, however, challenged this assumption and shown that longevity and reproduction are not inextricably linked. In this study, we showed that beetles infected by cysticercoids of the tapeworm Hymenolepis diminuta increased their total food intake and, more particularly, their carbohydrate consumption compared with uninfected insects.

Expression of Caenorhabditis elegans RNA-directed RNA polymerase in transgenic Drosophila melanogaster does not affect morphological development.

Drosophila melanogaster, along with all insects and the vertebrates, lacks an RdRp gene. We created transgenic strains of Drosophila melanogaster in which the rrf-1 or ego-1 RdRp genes from C. elegans were placed under the control of the yeast GAL4 upstream activation sequence.

CUTI-1: A novel tetraspan protein involved in C. elegans CUTicle formation and epithelial integrity.

The nematode cuticle is a tough extracellular matrix composed primarily of cross-linked collagens and non-collagenous cuticulins. It is required for nematode motility and protection from the external environment. Little is known about how the complex process of cuticle formation has been adapted to the specialized requirements of the nematode cuticle, which is structurally and compositionally unique from other organisms.

Molecular imaging of endothelial vascular cell adhesion molecule-1 expression and inflammatory cell recruitment during vasculogenesis and ischemia-mediated arteriogenesis.

Background: Inflammatory responses contribute to vascular remodeling during tissue repair or ischemia. We hypothesized that inflammatory cell recruitment and endothelial cell activation during vasculogenesis and ischemia-mediated arteriogenesis could be temporally assessed by noninvasive molecular imaging.

Methods And Results: Contrast ultrasound perfusion imaging and molecular imaging with microbubbles targeted to activated neutrophils, alpha(5)-integrins, or vascular cell adhesion molecule (VCAM-1) were performed in murine models of vasculogenesis (subcutaneous matrigel) or hind-limb ischemia produced by arterial occlusion in wild-type or monocyte chemotactic protein-1-deficient mice.

Target identification and validation for anthelmintic discovery.

Anthelmintics presently used in humans were discovered using empirical biological screening processes targeting helminths of veterinary importance. The modern approach to drug discovery is based on genetic, bioinformatic and genomic identification of protein targets followed by specific validation assays and high-throughput screening using chemical libraries. Existing broad-spectrum anthelmintics bind just three classes of molecular targets; more classes of targets are urgently needed.

High-resolution myocardial perfusion imaging in mice with high-frequency echocardiographic detection of a depot contrast agent.

High-resolution methods for assessing myocardial perfusion in murine models of cardiovascular disease are needed. We hypothesized that regional hypoperfusion could be assessed with ultrahigh-frequency myocardial contrast echocardiography (MCE) and a novel strategy of depot contrast enhancement. MCE was performed with 30-MHz transthoracic imaging 10 seconds and 10 minutes after intravenous administration of microbubbles in control mice, and in mice after left anterior descending coronary artery ligation.

Effect of microbubble ligation to cells on ultrasound signal enhancement: implications for targeted imaging.

Objectives: Molecular imaging with contrast-enhanced ultrasound (CEU) relies on the detection of microbubbles retained in regions of disease. The aim of this study was to determine whether microbubble attachment to cells influences their acoustic signal generation and stability.

Materials And Methods: Biotinylated microbubbles were attached to streptavidin-coated plates to derive density versus intensity relations during low- and high-power imaging.

Cellular and molecular imaging with targeted contrast ultrasound.

There is growing interest in the availability of methods for imaging disease at the level of the cellular and/or molecular mediators. Techniques for imaging molecular alterations have been develop for essentially all non-invasive cardiac imaging modalities. Molecular imaging with contrast-enhanced ultrasound relies on the detection of novel site-targeted contrast agents.

Heritable and inducible gene knockdown in C. elegans using Wormgate and the ORFeome.

Double-stranded RNA (dsRNA) mediated gene silencing (RNA interference; RNAi) is a powerful tool for investigating gene function. It is usually performed in Caenorhabditis elegans via the injection or oral delivery of dsRNA, but an alternative approach, the expression of RNA hairpins from introduced DNA (hairpin RNAi; hpRNAi) has several advantages: (1) it can be induced systemically or in a tissue-specific manner; (2) because it is heritable, it allows consistent RNAi silencing across a whole population of genetically identical animals; and (3) it can be applied in refractory tissue such as neurons. hpRNAi has not been widely used to investigate gene function because a number of steps are relatively inefficient and labour-intensive.

RNAi-based discovery and validation of new drug targets in filarial nematodes.

Human filarial nematodes cause river blindness and lymphatic filariasis, both of which are diseases that produce considerable morbidity. Control of these diseases relies on drug treatments that are ineffective against macrofilariae and are threatened by the development of resistance. New validated drug targets are required to allow development of new classes of antifilarial drugs.

Clinical correlates and mortality of hemodynamically significant tricuspid regurgitation.

Background And Aim Of Study: Limited data exist regarding the etiologies and prognostic significance of severe tricuspid regurgitation (TR) in the modern medical era. This retrospective chart review examines the causes of, and mortality associated with, hemodynamically significant TR.

Methods: The database of the echocardiography laboratory at a major academic medical center was searched from August 2000 to October 2001, identifying 91 patients (1.

Tritrichomonas foetus and Trichomonas vaginalis: the pattern of inactivation of hydrogenase activity by oxygen and activities of catalase and ascorbate peroxidase.

The concentration-dependence of the inhibition of whole-cell hydrogen formation by oxygen has been measured in the trichomonads Trichomonas vaginalis and Tritrichomonas foetus, and compared with the oxygen inhibition of the in situ hydrogenase activity as measured by a tritium exchange assay. The inhibition profiles closely paralleled each other, suggesting that hydrogenase is the primary site of inhibition of anaerobic fermentative metabolism. In addition the inhibition profile for isolated hydrogenosomes was measured and shown to be similar to that for whole organisms.