Strote G (1985) Trop Med Parasitol "Development of infective larvae of Onchocerca volvulus in diffusion chambers implanted into Mastomys natalensis."

Strote G

[Trop Med Parasitol, 1985]

Diffusion chambers containing vector-derived infective larvae of O. volvulus were implanted into male Mastomys natalensis and removed after periods up to 100 days. Nearly all chambers contained motile living parasites. After two weeks lengths and diameters of the larvae had increased significantly and after 100 days one juvenile worm showed well developed papillae at the posterior end.

Jessica Smith et al. (1999) International C. elegans Meeting "When humans lead the way: uncovering the role of C27H5.1"

Michelle Chambers, Dave Pilgrim, Jessica Smith

[International C. elegans Meeting, 1999]

C27H5.1 is a weak homologue of UNC-119, a gene involved in axon guidance and outgrowth. We first became interested in C27H5.1 because of its similarity to UNC-119. We have since learned that there is a mammalian homologue of C27H5.1; rod phosphodiesterase delta subunit PDE6D. These two proteins are very highly conserved exhibiting 70% identity and 85% similarity. UNC-119 also has a close mammalian homologue; retinal protein HRG4/RRG4. Both C27H5.1 and UNC-119 are pan-neuronal in C. elegans while HRG4 and PDE6D are expressed in the mammalian retina. The conservation of these genes has led us to speculate that they may constitute a new protein family. While UNC-119 has been fairly well characterized, very little is known about C27H5.1. Based upon its conservation with UNC-119 and PDE6D, we suspect that C27H5.1 is playing an important role, perhaps in nervous system development. However, C27H5.1 may play a more general role. Unlike UNC-119, C27H5.1 expression is not limited to the nervous system. There is also expression in pharyngeal and vulval muscle. To determine this role, we have performed RNA interference against C27H5.1. Unfortunately, no phenotype was observed. Subsequently we performed RNAi against GFP under the control of the C27H5.1 promoter. There was no reduction in fluorescence suggesting that the expression of C27H5.1 is not affected by RNAi. We are currently screening for a deletion in C27H5.1. Although we have not yet been successful in determining the C27H5.1 mutant phenotype, studies with its mammalian homologue, PDE6D, suggest a possible role for this protein. PDE6D has been shown to bind to and solubilize rod phosphodiesterase (PDE). Since PDE6D expression is not limited to the retina, PDE d may regulate the membrane binding of a variety of proteins. Interestingly, C27H5.1 also binds human rod phosphodiesterase, suggesting that there is at least some functional conservation between PDE d and C27H5.1.

Lange AM et al. (1994) J Immunol "IL-4- and IL-5-dependent protective immunity to Onchocerca volvulus infective larvae in BALB/cBYJ mice."

Scott P, Lange AM, Abraham D, Yutanawiboonchai W

[J Immunol, 1994]

A significant reduction in challenge worm survival occurred when BALB/cBYJ mice were vaccinated against Onchocerca volvulus infective third stage larvae (L3) by using irradiated O. volvulus L3. Challenge infections consisted of L3 implanted in diffusion chambers, which were used as a means to contain, and thus efficiently recover, the larvae from the host. The goal of the present study was to describe the mechanism of immune-mediated killing of O. volvulus L3 in diffusion chambers in mice. Direct contact between host cells and parasites was required for killing of larvae in immunized hosts. To define the mechanism of immune-mediated killing in this system, the time of influx of cells and cytokines into the infection site was compared with the time challenge infections were killed. The only cell type that was found to increase in diffusion chambers in immunized mice was eosinophils; maximal levels of eosinophils were coincident with the time of parasite killing. IL-5 was found in diffusion chambers of immunized mice coincident with the time of parasite killing; IL-5 was not found in diffusion chambers recovered from control mice. Significant levels of IFN-gamma were absent in the diffusion chambers of both groups. Immunized mice were treated with mAb to eliminate IL-5 or IL-4 to assess the role these cytokines or their by-products play in larval killing. Elimination of either IL-5 or IL-4 significantly reduced the protective effects of vaccination against larval O. volvulus.

Bianco AE et al. (1989) J Helminthol "Fate of developing larvae of Onchocerca lienalis and O. volvulus in micropore chambers implanted into laboratory hosts."

Bianco AE, Ham PJ, Mustafa MB

[J Helminthol, 1989]

Infective larvae of Onchocerca lienalis and O. volvulus implanted subcutaneously within micropore chambers into laboratory hosts moulted to the fourth stage (L4) and underwent limited development and growth. Similar recoveries of O. lienalis L4 larvae in the range of 33-66% were obtained from chambers implanted into CBA and BALB/c strains of mice, jirds, and the natural bovine host. A relatively constant proportion of larvae survived up to 24 days post implantation and thereafter recoveries declined, although some worms were still alive after 96 days. Recoveries of O. volvulus L4 larvae from chambers given to normal or T-cell deprived mice were equivalent to one another and to those obtained with O. lienalis. Moulting of O. lienalis in chambers was observed on days 3 and 5, in close accordance with the timing of the third moult in cattle following systemic infection. Moulting of O. volvulus occurred between days 3-6. Morphological changes in developing larvae included a small but significant increase in length, a transient increase in width, and early development of the spicular primordia and genital tube. L4 larvae of O. lienalis, but not those of O. volvulus, exhibited 3 distinct caudal papillae not present on infective larvae.

Hulme SE et al. (2010) Lab Chip "Lifespan-on-a-chip: microfluidic chambers for performing lifelong observation of C. elegans."

Fontana W, Shevkoplyas SS, Whitesides GM, Apfeld J, Hulme SE, McGuigan AP

[Lab Chip, 2010]

This article describes the fabrication of a microfluidic device for the liquid culture of many individual nematode worms (Caenorhabditis elegans) in separate chambers. Each chamber houses a single worm from the fourth larval stage until death, and enables examination of a population of individual worms for their entire adult lifespans. Adjacent to the chambers, the device includes microfluidic worm clamps, which enable periodic, temporary immobilization of each worm. The device made it possible to track changes in body size and locomotion in individual worms throughout their lifespans. This ability to perform longitudinal measurements within the device enabled the identification of age-related phenotypic changes that correlate with lifespan in C. elegans.

Lange AM et al. (1993) Am J Trop Med Hyg "Induction of protective immunity against larval Onchocerca volvulus in a mouse model."

Abraham D, Lange AM, Yutanawiboonchai W, Lok JB, Trpis M

[Am J Trop Med Hyg, 1993]

BALB/cBYJ mice were immunized against larval Onchocerca volvulus by subcutaneous injection of normal, irradiated, or freeze-thaw-killed Onchocerca sp. larvae. The mice received challenge infections of O. volvulus third-stage larva (L3) contained in diffusion chambers implanted subcutaneously. At two-weeks postinfection, the diffusion chambers were removed and larval survival was assessed. When mice were immunized a single time with 35-krad-irradiated or normal O. volvulus L3, there was a significant reduction in the survival of challenge parasites. However, there was little or no reduction in challenge worm survival when mice were immunized a single time with freeze-thaw-killed O. volvulus L3 or fourth-stage larva (L4), or irradiated O. lienalis L3. When a second dose of freeze-thaw killed O. volvulus L3 or irradiated O. lienalis L3 was administered, there was a significant reduction in parasite survival in immunized mice. Immunization with O. volvulus L4 or a combination of L3 and L4 failed to confer protection. These results demonstrate that mice can be immunized against larval O. volvulus and that diffusion chambers are an efficient method for studying protective immunity to this parasite in a mouse model.

Song P et al. (2015) Biomed Microdevices "A microfluidic device for efficient chemical testing using Caenorhabditis elegans."

Hekimi S, Bernard K, Liu X, Sobolevski A, Zhang W, Song P

[Biomed Microdevices, 2015]

The nematode worm Caenorhabditis elegans has been employed as a popular model organism in many fields of biological research. In this paper, we present a microfluidic device for facilitating chemical testing using C. elegans. For testing chemicals on chip, the device houses single nematodes in microfluidic chambers and precisely adjusts the chamber's chemical environment during experiments. Eight nematodes can be readily loaded into the chambers through separate loading channels in a quick and gentle manner. In addition, a custom-made software with a graphic user interface is also created for quantitative analysis of locomotion parameters (swimming frequency and bend amplitude) of the nematodes in response to chemical stimuli, thus greatly enhancing the efficiency of data collection. We perform proof-of-concept experiments using two chemicals, zinc ion (Zn(2+)) and glucose, to demonstrate the effectiveness of the microfluidic device.

Ghorashian N et al. (2010) Neuronal Development, Synaptic Function and Behavior, Madison, WI "A Parallelized Microfluidic Chamber Device for High-Throughput Nerve Regeneration Studies in C. elegans"

Ghorashian N, Hilliard M A, Ben-Yakar A

[Neuronal Development, Synaptic Function and Behavior, Madison, WI, 2010]

We fabricated and tested a high-throughput microfluidic platform to study nerve regeneration in C. elegans. The device consists of an array of small chambers in a parallel fluidic circuit allowing for simultaneous trapping of dozens of C. elegans worms in individual visualization chambers for in-vivo imaging and laser ablation of fluorescently labeled axons. With proper liquid nutrients, the animals can easily survive in the microfluidic chambers for three days or more for monitoring nerve regeneration. This device could serve as the optical and fluidic interface for automated genome-wide nerve regeneration studies using femtosecond laser nano-axotomy and fluorescence microscopy. Using our device and conventional methods, we investigated the regenerative capacity of the oxygen sensory neuron, PQR. This neuron is located in the left lumbar ganglion on the posterior-lateral side of the worm's body, and has only two processes emerging from the cell body – a dendrite extending posterior toward the tip of the tail and an axon extending anterior joining the ventral nerve cord. We looked at regeneration rates in animals in which either only one or both neurites were severed. We observed that the dendrite process regenerated with a higher frequency when the axon was simultaneously severed. This result suggests that the molecular machinery responsible for regeneration is more efficiently recruited in a given process when there is additional damage to other parts of the neuron.

Kim J et al. (2021) Nat Commun "Maintenance of quiescent oocytes by noradrenergic signals."

Hyun M, You YJ, Kim J, Hibi M

[Nat Commun, 2021]

All females adopt an evolutionary conserved reproduction strategy; under unfavorable conditions such as scarcity of food or mates, oocytes remain quiescent. However, the signals to maintain oocyte quiescence are largely unknown. Here, we report that in four different species - Caenorhabditis elegans, Caenorhabditis remanei, Drosophila melanogaster, and Danio rerio - octopamine and norepinephrine play an essential role in maintaining oocyte quiescence. In the absence of mates, the oocytes of Caenorhabditis mutants lacking octopamine signaling fail to remain quiescent, but continue to divide and become polyploid. Upon starvation, the egg chambers of D. melanogaster mutants lacking octopamine signaling fail to remain at the previtellogenic stage, but grow to full-grown egg chambers. Upon starvation, D. rerio lacking norepinephrine fails to maintain a quiescent primordial follicle and activates an excessive number of primordial follicles. Our study reveals an evolutionarily conserved function of thenoradrenergic signal in maintaining quiescent oocytes.

Steele LM et al. (2018) Methods Enzymol "Approaches to Anesthetic Mechanisms: The C. elegans Model."

Steele LM, Sedensky MM

[Methods Enzymol, 2018]

Understanding the mechanisms of volatile anesthetics has been a complex problem that has intrigued investigators for decades. Through the use of relatively simple model organisms-including the nematode Caenorhabditis elegans-progress has been made. Like any model system, C. elegans has both advantages and disadvantages, which are discussed in this chapter. Methods are provided for exposing worms to volatile anesthetics in airtight glass chambers, and for measuring the concentrations of anesthetic in the chambers by gas chromatography. In addition, various behavioral assays are described for characterizing the worms' responses to anesthetics. C. elegans identified proteins that play a role in anesthetic sensitivity that are highly conserved in other organisms, including humans. With precisely characterized neural development, C. elegans has also afforded an excellent opportunity to study anesthetic-induced neurotoxicity. Continued progress in understanding anesthetic action is anticipated from the ongoing study of C. elegans and other animal models.