Spatial patterns of avian malaria prevalence in Zonotrichia capensis on the western slope of the Peruvian Andes

Environmental heterogeneity largely dictates the spatial distributions of parasites and therefore the susceptibility to infection of host populations. We surveyed avian malaria infections in Rufous-collared sparrows (Zonotrichia capensis) across replicated altitudinal and latitudinal transects along the western slope of the Peruvian Andes to assess geographic patterns of prevalence. We found malaria infection prevalence peaked at midelevations along all 3 altitudinal transects (x ≈ 2,733 m), with highest overall prevalence observed in the northern transect. We observed low levels of malarial parasite diversity, with 94% of infected birds carrying a single Haemoproteus (subgenus Parahaemoproteus) strain. The remaining infected birds harbored either a single alternate Haemoproteus or 1 of 2 Plasmodium strains. Our data suggest that temperature and precipitation are the primary drivers of the spatial patterns in avian malaria prevalence along the western slope of the Andes.

RNA-seq analysis of the C. briggsae transcriptome

Curation of a high-quality gene set is the critical first step in genome research, enabling subsequent analyses such as ortholog assignment, cis-regulatory element finding, and synteny detection. In this project, we have reannotated the genome of Caenorhabditis briggsae, the best studied sister species of the model organism Caenorhabditis elegans. First, we applied a homology-based gene predictor genBlastG to annotate the C. briggsae genome. We then validated and further improved the C. briggsae gene annotation through RNA-seq analysis of the C. briggsae transcriptome, which resulted in the first validated C. briggsae gene set (23,159 genes), among which 7347 genes (33.9% of all genes with introns) have all of their introns confirmed. Most genes (14,812, or 68.3%) have at least one intron validated, compared with only 3.9% in the most recent WormBase release (WS228). Of all introns in the revised gene set (103,083), 61,503 (60.1%) have been confirmed. Additionally, we have identified numerous trans-splicing leaders (SL1 and SL2 variants) in C. briggsae, leading to the first genome-wide annotation of operons in C. briggsae (1105 operons). The majority of the annotated operons (564, or 51.0%) are perfectly conserved in C. elegans, with an additional 345 operons (or 31.2%) somewhat divergent. Additionally, RNA-seq analysis revealed over 10 thousand small-size assembly errors in the current C. briggsae reference genome that can be readily corrected. The revised C. briggsae genome annotation represents a solid platform for comparative genomics analysis and evolutionary studies of Caenorhabditis species.

The atm-1 gene is required for genome stability in Caenorhabditis elegans

The Ataxia-telangiectasia-mutated (ATM) gene in humans was identified as the basis of a rare autosomal disorder leading to cancer susceptibility and is now well known as an important signal transducer in response to DNA damage. An approach to understanding the conserved functions of this gene is provided by the model system, Caenorhabditis elegans. In this paper we describe the structure and loss of function phenotype of the ortholog atm-1. Using bioinformatic and molecular analysis we show that the atm-1 gene was previously misannotated. We find that the transcript is in fact a product of three gene predictions, Y48G1BL.2 (atm-1), K10E9.1, and F56C11.4 that together make up the complete coding region of ATM-1. We also characterize animals that are mutant for two available knockout alleles, gk186 and tm5027. As expected, atm-1 mutant animals are sensitive to ionizing radiation. In addition, however, atm-1 mutants also display phenotypes associated with genomic instability, including low brood size, reduced viability and sterility. We document several chromosomal fusions arising from atm-1 mutant animals. This is the first time a mutator phenotype has been described for atm-1 in C. elegans. Finally we demonstrate the use of a balancer system to screen for and capture atm-1-derived mutational events. Our study establishes C. elegans as a model for the study of ATM as a mutator potentially leading to the development of screens to identify therapeutic targets in humans.

Intravascular frequency-domain optical coherence tomography assessment of atherosclerosis and stent-vessel interactions in human carotid arteries

BACKGROUND AND PURPOSE

Carotid artery-related stroke is largely an embolic disease that has been correlated with inflammation, plaque rupture, and thrombus formation in "vulnerable" atherosclerotic plaque. Nevertheless, current guidelines for carotid revascularization in asymptomatic patients rely on the calculation of stenosis for risk assessment, a parameter that has been viewed with increasing skepticism. Intravascular OCT is an imaging technique that offers high axial resolution (10 μm), allowing an unprecedented micron-level assessment of human carotid plaque morphology. This observational article reports the first successful use of the newest iteration of this technology, FDOCT without balloon occlusion to assess human carotid artery disease and carotid stent-vessel interaction in vivo.

MATERIALS AND METHODS

Four patients with asymptomatic carotid artery disease and ambiguous noninvasive and/or angiographic data underwent carotid FDOCT to assess risk and to formulate a treatment strategy.

RESULTS

Findings include the unexpected demonstration of TCFAs, plaque rupture, thrombus, inflammation, and marked tissue prolapse through stent struts in patients without high-risk factors by conventional criteria, as well as low-risk features in a patient with a high-risk noninvasive study. The procedures were performed without safety issues or special accommodations for vessel occlusion.

CONCLUSIONS

The present study demonstrates the technical feasibility of FDOCT in cervical carotid arteries. As such, this technology holds the promise of not only clarifying ambiguous data in individual patients but of providing data that might call for a future paradigm shift in the assessment of asymptomatic carotid artery disease.

Effects of colesevelam on glucose absorption and hepatic/peripheral insulin sensitivity in patients with type 2 diabetes mellitus

AIM

Colesevelam lowers glucose and low-density lipoprotein cholesterol levels in patients with type 2 diabetes mellitus. This study examined the mechanisms by which colesevelam might affect glucose control.

METHODS

In this 12-week, randomized, double-blind, placebo-controlled study, subjects with type 2 diabetes and haemoglobin A(1c) (HbA(1c)) ≥7.5% on either stable diet and exercise or sulphonylurea therapy were randomized to colesevelam 3.75 g/day (n = 16) or placebo (n = 14). Hepatic/peripheral insulin sensitivity was evaluated at baseline and at week 12 by infusion of (3) H-labelled glucose followed by a 2-step hyperinsulinemic-euglycemic clamp. Two 75-g oral glucose tolerance tests (OGTTs) were conducted at baseline, one with and one without co-administration of colesevelam. A final OGTT was conducted at week 12. HbA(1c) and fasting plasma glucose (FPG) levels were evaluated pre- and post-treatment.

RESULTS

Treatment with colesevelam, compared to placebo, had no significant effects on basal endogenous glucose output, response to insulin or on maximal steady-state glucose disposal rate. At baseline, co-administration of colesevelam with oral glucose reduced total area under the glucose curve (AUC(g)) but not incremental AUC(g). At week 12, neither total AUC(g) nor incremental AUC(g) were changed from pre-treatment values in either group. Post-load insulin levels increased with colesevelam at 30 and 120 min, but these changes in total area under the insulin curve (AUC(i)) and incremental AUC(i) did not differ between groups. Both HbA(1c) and FPG improved with colesevelam, but treatment differences were not significant.

CONCLUSIONS

Colesevelam does not affect hepatic or peripheral insulin sensitivity and does not directly affect glucose absorption.

Specialized chromosomes and their uses in Caenorhabditis elegans

Research on Caenorhabditis elegans involves the use of a wide range of genetic and molecular tools consisting of chromosomal material captured and modified for specific purposes. These "specialized chromosomes" come in many forms ranging from relatively simple gene deletions to complex rearrangements involving endogenous chromosomes as well as transgenic constructs. In this chapter, we describe the specialized chromosomes that are available in C. elegans, their origins, practical considerations, and methods for generation and evaluation. We will summarize their uses for biological studies, and their contribution to our knowledge about chromosome biology.

Association study of four key folliculogenesis genes in polycystic ovary syndrome

Polycystic ovaries and impaired fertility are the result of abnormal folliculogenesis. Our objective was to determine the role of four candidate folliculogenesis genes in the development of polycystic ovary syndrome (PCOS). Women with and without PCOS (335 cases; 198 controls) were genotyped for single nucleotide polymorphisms in GDF9, BMP15, AMH, and AMHR2. Variants in these genes were not associated with PCOS. Certain GDF9 variants were associated with hirsutism scores and parity in PCOS patients. GDF9 may thus serve as a modifier gene. These results suggest that inherited defects in folliculogenesis are not major factors in the genetic susceptibility to PCOS.

Genomic sequence of a mutant strain of Caenorhabditis elegans with an altered recombination pattern

Background

The original sequencing and annotation of the Caenorhabditis elegans genome along with recent advances in sequencing technology provide an exceptional opportunity for the genomic analysis of wild-type and mutant strains. Using the Illumina Genome Analyzer, we sequenced the entire genome of Rec-1, a strain that alters the distribution of meiotic crossovers without changing the overall frequency. Rec-1 was derived from ethylmethane sulfonate (EMS)-treated strains, one of which had a high level of transposable element mobility. Sequencing of this strain provides an opportunity to examine the consequences on the genome of altering the distribution of meiotic recombination events.

Results

Using Illumina sequencing and MAQ software, 83% of the base pair sequence reads were aligned to the reference genome available at Wormbase, providing a 21-fold coverage of the genome. Using the software programs MAQ and Slider, we observed 1124 base pair differences between Rec-1 and the reference genome in Wormbase (WS190), and 441 between the mutagenized Rec-1 (BC313) and the wild-type N2 strain (VC2010). The most frequent base-substitution was G:C to A:T, 141 for the entire genome most of which were on chromosomes I or X, 55 and 31 respectively. With this data removed, no obvious pattern in the distribution of the base differences along the chromosomes was apparent. No major chromosomal rearrangements were observed, but additional insertions of transposable elements were detected. There are 11 extra copies of Tc1, and 8 of Tc2 in the Rec-1 genome, most likely the remains of past high-hopper activity in a progenitor strain.

Conclusion

Our analysis of high-throughput sequencing was able to detect regions of direct repeat sequences, deletions, insertions of transposable elements, and base pair differences. A subset of sequence alterations affecting coding regions were confirmed by an independent approach using oligo array comparative genome hybridization. The major phenotype of the Rec-1 strain is an alteration in the preferred position of the meiotic recombination event with no other significant phenotypic consequences. In this study, we observed no evidence of a mutator effect at the nucleotide level attributable to the Rec-1 mutation.

Long-term Safety and Tolerability of Colesevelam HCl in Subjects with Type 2 Diabetes

The bile acid sequestrant, colesevelam hydrochloride, is approved for glycemic control in adults with type 2 diabetes. In three double-masked, placebo-controlled studies, colesevelam hydrochloride 3.75 g/day demonstrated its glycemic-lowering properties when added to existing metformin-, insulin-, or sulfonylurea-based therapy in adults with inadequately controlled type 2 diabetes. This was a 52-week open-label extension study conducted at 63 sites in the United States and one site in Mexico to further evaluate the safety and tolerability of colesevelam hydrochloride in subjects with type 2 diabetes. All subjects who completed the three double-masked, placebo-controlled studies were eligible to enroll in this open-label extension. In total, 509 subjects enrolled and received open-label colesevelam hydrochloride 3.75 g/day for 52 weeks. Safety and tolerability of colesevelam hydrochloride was evaluated by the incidence and severity of adverse events. In total, 360 subjects (70.7%) completed the extension. Of the safety population, 361 subjects (70.9%) experienced an adverse event, most (88.1%) being mild or moderate in severity. Fifty-six adverse events (11.0%) were drug-related; the most frequent drug-related adverse events were constipation and dyspepsia. Thirty-five subjects (6.9%) discontinued due to an adverse event. Fifty-four subjects (10.6%) experienced a serious adverse event; only one was considered drug-related (diverticulitis). Seventeen subjects (3.3%) experienced hypoglycemia; most episodes were mild or moderate in severity. Glycemic improvements with colesevelam hydrochloride were seen without change in weight over 52 weeks (0.2 kg mean reduction from baseline). Colesevelam hydrochloride was safe and well-tolerated as long-term therapy for patients with type 2 diabetes.

High-resolution array comparative genomic hybridization analysis reveals unanticipated complexity of genetic deficiencies on chromosome V in Caenorhabditis elegans

Genomic rearrangements are widely used in Caenorhabditis elegans research but many remain incompletely characterized at the physical level. We have used oligo-array comparative genomic analysis to assess the physical structure of 20 deficiencies and a single duplication of chromosome V. We find that while deletions internal to the chromosome appear simple in structure, terminal deletions are complex, containing duplications in addition to the deletion. Additionally, we confirm that transposon-induced deficiencies contain breakpoints that initiate at Tc1 elements. Finally, 13 of these deficiencies are known to suppress recombination far beyond the extent of the deletion. These deficiencies fall into two classes: strong and weak suppressors of adjacent recombination. Analysis of the deleted regions in these deficiencies reveals no common physical sites to explain the observed differences in recombination suppression. However, we find a strong correlation between the size of the rearranged chromosome and the severity of recombination suppression. Rearranged chromosomes that have a minor effect on recombination fall within 2% of normal chromosome size. Our observations highlight the use of array-based approaches for the analysis of rearranged genomes, revealing previously unidentified deficiency characteristics and addressing biologically relevant questions.

Dysregulation of neurosteroids in obsessive compulsive disorder

Alterations in hormone concentrations, including adrenocorticotropin, corticotropin releasing hormone, and cortisol have been reported in patients with obsessive compulsive disorder (OCD). Dehydroepiandrosterone (DHEA) and its sulfated metabolite, DHEA-S, have not been assessed in patients with OCD. We report 24-h serum DHEA, DHEA-S, and cortisol concentrations in a young man with OCD and 15 healthy young men. Circadian patterns of DHEA and cortisol were markedly different in the subject with OCD than in the control subjects. DHEA and DHEA-S concentrations were substantially higher in the OCD subject than in the control subjects. In contrast, cortisol concentrations were similar in the OCD subject and the control subjects. Future clinical studies are needed to evaluate the significance of DHEA and DHEA-S in OCD.

Attenuation characteristics of MagnaDense high-density concrete at 6, 10 and 15 mv for use in radiotherapy bunker design

The attenuation characteristics of MagnaDense high-density concrete are measured using the x-ray beams from two Varian linear accelerators at nominal 6, 10, and 15 megavolt energies. The tenth value layers for the primary beam are evaluated under broad- and narrow-beam conditions. The attenuation of secondary radiation is also investigated. Measured data are compared with existing data used in radiotherapy bunker design, derived from the scaling of published tenth value layers for ordinary concrete according to physical density. Instantaneous dose rates around an existing bunker with MagnaDense concrete walls and a conventional concrete roof are predicted using the various different data and compared to actual dose-rate measurements. Primary beam tenth value layer values derived from the broad-beam measurements are found to represent the attenuation properties of the MagnaDense more accurately than those produced by density-based scaling or from narrow-beam measurements.

Oligonucleotide Array Comparative Genomic Hybridization (oaCGH) based characterization of genetic deficiencies as an aid to gene mapping in Caenorhabditis elegans

Background:

A collection of genetic deficiencies covering over 70% of the Caenorhabditis elegans genome exists, however the application of these valuable biological tools has been limited due to the incomplete correlation between their genetic and physical characterization.

Results:

We have applied oligonucleotide array Comparative Genomic Hybridization (oaCGH) to the high resolution, molecular characterization of several genetic deficiency and duplication strains in a 5 Mb region of Chromosome III. We incorporate this data into a physical deficiency map which is subsequently used to direct the positional cloning of essential genes within the region. From this analysis we are able to quickly determine the molecular identity of several previously unidentified mutations.

Conclusion:

We have applied accurate, high resolution molecular analysis to the characterization of genetic mapping tools in Caenorhabditis elegans. Consequently we have generated a valuable physical mapping resource, which we have demonstrated can aid in the rapid molecular identification of mutations of interest.

Polymorphism of the follistatin gene in polycystic ovary syndrome

Follistatin has been reported as a candidate gene for polycystic ovary syndrome (PCOS) from linkage and association studies. Acting to regulate the development of ovarian follicles and as an antagonist to aromatase activity, alterations in follistatin function or expression may result in key features of PCOS such as reduced serum FSH, impaired ovarian follicle development and augmented ovarian androgen production. We investigated polymorphisms in the FST gene to determine if genetic variation is associated with susceptibility to PCOS or key phenotypic features of PCOS patients in a case-control association study. One hundred and seventy-three PCOS patients of Caucasian descent (mean age 30.0 +/- 4.8 years), conforming to the NIH diagnostic criteria, were recruited from a clinical practice database and 107 normal ovulating women (mean age 38.8 +/- 13.4 years) were recruited from the general community as control subjects. Morphometric data, biochemistry and genomic DNA were collected from study subjects and genotyping was performed on seven Single nucleotide polymorphisms (SNPs) in the FST gene region. Allele frequencies of the SNPs were rs1423560 G/C (0.99/0.01), rs3797297 C/A (0.80/0.20), rs11745088 C/G (0.98/0.02), rs3203788 A/T (0.98/0.02) and rs1062809 G/C (1.00/-), rs1127760 A/T (0.98/0.02) and rs1127761 A/T (0.98/0.02), and these were not significantly different between the PCOS and control groups (P < 0.05). Statistical analysis revealed significant associations between the SNP rs3797297 and sex hormone-binding globulin (P = 0.04) and free androgen index (FAI) (P < 0.01). We conclude that FST is not a susceptibility locus for PCOS; however, the SNP rs3797297 from FST gene was associated with androgenic markers for PCOS and may be of importance in the hyperandrogenaemia of the disease.

Bloodstream infections in a secondary and tertiary care hospital setting

BACKGROUND

Bloodstream infections (BSI) occurring in community and health-care settings vary with the patient group and treatment of underlying medical conditions. We studied the clinical infectious syndromes occurring in patients with positive blood cultures routinely obtained at a regional secondary and tertiary care hospital.

METHODS

BSI were categorized as either community-acquired (C-BSI), or health-care-associated (H-BSI) acquired either as a (i) non-inpatient (outpatient) or (ii) hospital inpatient. Clinical information was collected prospectively during the 1-year study.

RESULTS

There were 193 C-BSI and 230 H-BSI. The large majority of C-BSI were caused by bacterial pathogens susceptible to narrow-spectrum antibiotics, particularly in children. Cefuroxime was active against 90% of C-BSI isolates and 46% of H-BSI isolates, excluding anaerobes. Of all H-BSI, the 35% occurring in outpatients had a similar source, microbiological cause and bacterial susceptibilities to the inpatients. H-BSI were infrequently due to enterococci (4%), Candida (3%) or methicillin-resistant Staphylococcus aureus (0.4%). No BSI were due to vancomycin-resistant enterococci or extended-spectrum beta-lactamase producing Enterobacteriaciae. I.v. catheters, predominantly central lines, were the source of 60% of all H-BSI, mostly in haematology-oncology or neonatal patients. Mortality at 1 month was 12% overall for both C-BSI and H-BSI, varying markedly by underlying disease and increasing age (for C-BSI).

CONCLUSION

In this population, C-BSI have remained susceptible to narrow-spectrum antibiotics, whereas H-BSI due to multiresistant organisms were rare. Obtaining a history of recent medical procedures is important for community patients presenting with a BSI.

Lipids in and around photosynthetic reaction centres

Reaction centres are membrane-embedded pigment-protein complexes that transduce the energy of sunlight into a biologically useful form. The most heavily studied reaction centres are the PS-I (Photosystem I) and PS-II complexes from oxygenic phototrophs, and the reaction centre from purple photosynthetic bacteria. A great deal is known about the compositions and structures of these reaction centres, and the mechanism of light-activated transmembrane electron transfer, but less is known about how they interact with other components of the photosynthetic membrane, including the membrane lipids. X-ray crystallography has provided high-resolution structures for PS-I and the purple bacterial reaction centre, and revealed binding sites for a number of lipids, either embedded in the protein interior or attached to the protein surface. These lipids play a variety of roles, including the binding of cofactors and the provision of structural support. The challenges of modelling surface-associated electron density features such as lipids, detergents, small amphiphiles and ions are discussed.

Rewiring photosynthesis: engineering wrong-way electron transfer in the purple bacterial reaction centre

The purple bacterial reaction centre uses light energy to separate charge across the cytoplasmic membrane, reducing ubiquinone and oxidizing a c-type cytochrome. The protein possesses a macroscopic structural two-fold symmetry but displays a strong functional asymmetry, with only one of two available membrane-spanning branches of cofactors (the so-called A-branch) being used to catalyse photochemical charge separation. The factors underlying this functional asymmetry have been the subject of study for many years but are still not fully understood. Site-directed mutagenesis has been partially successful in rerouting electron transfer along the normally inactive B-branch, allowing comparison of the kinetics of equivalent electron transfer reactions on the two branches. Both the primary and secondary electron transfer steps on the B-branch appear to be considerably slower than their A-branch counterparts. The effectiveness of different mutations in rerouting electron transfer along the B-branch of cofactors is discussed.

Temporal and spatial organization of doctors' computer usage in a UK hospital department

This paper describes the use of an application accessible via distributed desktop computing and wireless mobile devices in a specialist department of a UK acute hospital. Data (application logs, in-depth interviews, and ethnographic observation) were simultaneously collected to study doctors' work via this application, when and where they accessed different areas of it, and from what computing devices. These show that the application is widely used, but in significantly different ways over time and space. For example, physicians and surgeons differ in how they use the application and in their choice of mobile or desktop computing. Consultants and junior doctors in the same teams also seem to access different sources of patient information, at different times, and from different locations. Mobile technology was used almost exclusively during the morning by groups of clinicians, predominantly for ward rounds.

Animal models for the study of adenosine receptor function

Adenosine receptors represent a family of G-protein coupled receptors that are ubiquitously expressed in a wide variety of tissues. This family contains four receptor subtypes: A1 and A3, which mediate inhibition of adenylyl cyclase; and A2a and A2b, which mediate stimulation of this enzyme. Currently, all receptor subtypes have been genetically deleted in mouse models except for the A2b adenosine receptor, and some have been overexpressed in selective tissues of transgenic mice. Studies involving these transgenic mice indicated that receptor levels are rate limiting, as effects were amplified upon increases in receptor level. The knockout models pointed to clusters of activities related to the physiologies of the cardiovascular and the nervous systems, which are either reduced or enhanced upon specific receptor deletion. Interestingly, the trend of effects on these systems is similar in the A1 and A3 adenosine receptor knockout mice and opposite to the effects observed in the A2a adenosine receptor knockout model. This review summarizes in vitro studies on pathways affected by each adenosine receptor, and primarily focuses on the above in vivo models generated to investigate the physiologic role of adenosine receptors. Furthermore, it illustrates the need for multiple adenosine receptor subtype deficiency studies in mice and the deletion of the A2b subtype.

A functional genomic analysis of cell morphology using RNA interference

Background

The diversity of metazoan cell shapes is influenced by the dynamic cytoskeletal network. With the advent of RNA-interference (RNAi) technology, it is now possible to screen systematically for genes controlling specific cell-biological processes, including those required to generate distinct morphologies.

Results

We adapted existing RNAi technology in Drosophila cell culture for use in high-throughput screens to enable a comprehensive genetic dissection of cell morphogenesis. To identify genes responsible for the characteristic shape of two morphologically distinct cell lines, we performed RNAi screens in each line with a set of double-stranded RNAs (dsRNAs) targeting 994 predicted cell shape regulators. Using automated fluorescence microscopy to visualize actin filaments, microtubules and DNA, we detected morphological phenotypes for 160 genes, one-third of which have not been previously characterized in vivo. Genes with similar phenotypes corresponded to known components of pathways controlling cytoskeletal organization and cell shape, leading us to propose similar functions for previously uncharacterized genes. Furthermore, we were able to uncover genes acting within a specific pathway using a co-RNAi screen to identify dsRNA suppressors of a cell shape change induced by Pten dsRNA.

Conclusions

Using RNAi, we identified genes that influence cytoskeletal organization and morphology in two distinct cell types. Some genes exhibited similar RNAi phenotypes in both cell types, while others appeared to have cell-type-specific functions, in part reflecting the different mechanisms used to generate a round or a flat cell morphology.

"Computers can land people on Mars, why can't they get them to work in a hospital?" Implementation of an Electronic Patient Record System in a UK Hospital

OBJECTIVES

This paper aims to describe and interpret the implementation of a hospital information system in a large UK hospital.

METHODS

The paper is based on a longitudinal case study over a three-year period in which a cross section of hospital staff involved with the information system were interviewed.

RESULTS AND CONCLUSIONS

Ambitious government targets for the use of Information Technology in the UK National Health Service sit alongside a history of notable project failures. The decision by a UK hospital to install an advanced, integrated electronic patient record system therefore faced conflicting demands and expectations. This paper suggests that its simple categorisation as either a success or failure is problematic. Rather, the differing viewpoints that lead some clinicians to express "disappointment" with its performance, while others described its features as "tremendous" and managers suggested that the system had become "taken for granted" are explored. A number of broader phenomena relating to the organisational processes surrounding information systems implementation are also identified.

RNA-mediated interference as a tool for identifying drug targets

The nematode Caenorhabditis elegans is the first multicellular organism with a fully sequenced genome. As a model organism, C. elegans is playing a special role in functional genomic analyses because it is experimentally tractable on many levels. Moreover, the lessons learned from C. elegans are often applicable across phyla because many of the key biologic processes involved in development and disease have been well conserved. Many global approaches for analysing gene activity are being pursued in C. elegans. RNA-mediated interference (RNAi) is an efficient high-throughput method to disrupt gene function. The basic technique of RNAi involves introducing sequence-specific double-stranded RNA into C. elegans in order to generate a nonheritable, epigenetic knockout of gene function that phenocopies a null mutation in the targeted gene. This technique drastically reduces the time needed to jump from the identification of an interesting gene sequence to achieving an understanding of its function. Thus, RNAi facilitates the high-throughput functional analysis of gene targets identified during drug discovery. RNAi can also help to identify the biochemical mode of action of a drug or pesticide and to identify other genes encoding products that may respond or interact with specific compounds.