Worm Body Research Articles

Studies on monieziasis of sheep I. Prevalence and antihelminthic effects of some plant extracts, a light and electron microscopic study

Out of 2,343 examined sheep throughout the whole year, 271 were found to be infected with tapeworms (11.5%). The highest infection rate (22.1%) was recorded in autumn, while the lowest (6%) occurred in summer. Six species of cestodes were identified according to their prevalence: Moniezia expansa (74%), Moniezia denticulata (8.5%), Moniezia benedeni (4.8%), Moniezia trigonophora (2.7%), and Thysaniezia giardi (2.7%), T. giardi was recorded in Egypt for the first time. M. expansa was found throughout the year with two peaks in January (92.3%) and June (88.5%). SEM examination revealed that M. expansa scolex has four triangular suckers guarded by an X-shaped fibrous band that makes them open permanently. Also, there is a Y-shaped apical part at the scolex center which may be an embryonically non-developed rostellum. The whole worm body surface is covered with unidirectional microtriches. TEM showed that the tegument is underlaid by a thick fibrous interstitial layer below which an outer circular and an inner longitudinal muscular layer are arranged. Beneath these structures the subtegumental cells are found which have spherical electron-dense inclusions and various other cell organelles. Moreover, M. expansa has interproglottidal glands which contain secretory vesicles and secretions. For biological control of this parasite, different concentrations of crude plant extract of Artemisia cina were used in vitro and in vivo. In vitro, the results indicated that the plant extract is efficacious at all concentrations tested. Electron microscopic examination showed that many structures of the treated worms were affected. The most affected sites were the scolex and the microtriches of the outer tegumental surface. In vivo, treatment of heavily infected animals showed an antihelminthic effect, since the complete absence of eggs was recorded 9days after treatment when fecal investigations were done.

SISG: self‐immune automated signature generation for polymorphic worms

Purpose – The purpose of this paper is to propose a self‐immune automated signature generation (SISG) for polymorphic worms which is able to work well, even while being attacked by any types of malicious adversary and produces global‐suited signatures other than local‐suited signatures for its distributed architecture. Through experimentations, the method is thereafter evaluated.Design/methodology/approach – The ideal worm signature exist in each copy of the corresponding worm, but never in other worm categories and normal network traffic. SISG compares each worm copy and extract the same components, then produces the worm signature from the components which must achieve low‐false positive and low‐false negative. SISG is immune from the most attacks by filtering the harmful noise made by malicious adversaries before signature generation.Findings – NOP sled, worm body and descriptor are not good to be signature because they can be confused intricately by polymorphic engines. Protocol frames may not suit to...

Regeneration in the HemichordatePtychodera flava

When the body of P. flava is severed, the animal has the ability to regenerate its missing anterior or posterior as appropriate. We have focused on anterior regeneration when the head and branchial regions are severed from the body of the worm. After transection, the body wall contracts and heals closed in 2 to 3 days. By the third day a small blastema is evident at the point of closure. The blastema grows rapidly and begins the process of differentiating into a head with a proboscis and collar. At 5 days the blastema has increased greatly in size and differentiated into a central bulb, the forming proboscis, and two lateral crescents, the forming collar. Between 5 and 7 days a mouth opens ventral to the differentiating blastema. Over the next few days the lateral crescents extend to encircle the proboscis and mouth, making a fully formed collar. By 10 to 12 days a new head, sized to fit the worm's body, has grown attached to the severed site. At about this time the animal regains apparently normal burrowing behavior. After the head is formed, a second blastema-like area appears between the new head and the old body and a new branchial region is inserted by regeneration from this blastema over the next 2 to 3 weeks. The regenerating tissues are unpigmented and whitish such that in-situ hybridization can be used to study the expression of genes during the formation of new tissues.

Toxic effects and bioaccumulation of the herbicide isoproturon in Tubifex tubifex (Oligocheate, Tubificidae): A study of significance of autotomy and its utility as a biomarker

Tubifex is the only animal reported to respond with autotomy to contamination. This response of contaminated worm is understood as a mode of metal excretion. Few data concern the potential of organic compounds to induce tubifex autotomy. The objective of this study was to investigate if autotomy can be induced by a herbicide isoproturon (IP) and be related to the way of excretion. Isoproturon accumulation in worm tissues and its effect on tubifex mortality, autotomy and regeneration rates were analysed after 4 and 7 days of exposure to the herbicide and also when worms were replaced for 10 days in clean water. IP accumulated in the same way in all parts of the worm body but IP metabolite rates were significantly higher in the posterior part of the worm. Thus the loss of the posterior part allows the worm to eliminate an important amount of pesticide. Autotomy has a population importance and is related to the degree of worm contamination so it may become an interesting biomarker.

Fasciolagigantica: Parasitological and scanning electron microscopy study of the in vitro effects of ivermectin and/or artemether

Objective To evaluate the in vitro effects of different concentrations of ivermectin and/or artemether on Fasciola gigantica worms and to study the parasitological changes and tegumental alterations using scanning electron microscopy (SEM). Methods Fasciola gigantica worms were incubated in vitro for 24 and 48 h with three concentrations of either ivermectin or artemether (10, 20 and 50 μg/ml) or both in half concentration of either (5, 10 and 25 μg/ml). Results Exposure of Fasciola worms to 25 + 25 μg/ml of combined drug regimens or to 50 μg/ml of either ivermectin or artemether for 48 h led to 100%, 41.7% and 75% worm killing which were accompanied by a significant reduction in egg laying capacity and significant increase in dead eggs maximally recorded in combined drug regimens. SEM of the flukes incubated for 48 h with combined drug regimens showed maximal tegumental disruption with swelling of the worm body, roughness, blebbing, sloughing and complete loss of spines. Disruption to the tegument of the flukes induced by artemether was more than that of ivermectin. Conclusions Artemether alone or combined with ivermectin in half doses had potent fasciocidal activities. Besides, half doses of combined drug regimens had higher ovicidal effects than each drug alone. In vivo studies are recommended to explore the efficacy of combined regimens against Fasciola infection.

The in vitro effect of mefloquine and praziquantel against juvenile and adult Schistosoma japonicum

Mefloquine, an antimalarial drug, has been found to be effective against various stages of schistosomes in vivo. The purpose of the study is to explore the in vitro effect of mefloquine against adult and juvenile Schistosoma japonicum and to compare its efficacy with praziquantel. Three-hour-old schistosomula were prepared by penetrating the mouse skin with schistosome cercariae, while schistosomes 7-, 14-, and 35-day-old were collected from mice infected with S. japonicum cercariae for 7, 14, and 35 days by perfusion. Schistosomes were placed to each of 24 wells of a Falcon plate and maintained in Hanks' balanced salt solution-20% calf serum. Besides observation on the direct in vitro effect of mefloquine and praziquantel, adult worms exposed to mefloquine and praziquantel for 1 and 4 h were transferred to the medium without the drugs and incubated continuously for another 72 h. The reversible effect of mefloquine and praziquantel was assessed by the recovery of the worm motor activity and parasite survival. The minimal effective concentration of mefloquine against adult schistosomes in vitro was 10 microg/mL, which revealed that the worm motor activity was first stimulated, then decreased significantly, followed by bleb formation, focal swelling and elongation of the worm body, cessation of gut peristalsis, and death of 56.3% (18/32) worms within 24-72 h. Similar appearance was seen in the adult worms exposed to higher mefloquine concentration of 20 and 30 microg/mL, but all worms died within 4-24 h. The adult schistosomes exposed to praziquantel 1-30 microg/mL showed fast spasmodic contraction of the worm body, followed by bleb formation along the tegument, feeble movement of oral sucker, and death of a part of males and females 72 h after incubation. When male and female schistosomes exposed to mefloquine 10 and 20 microg/mL for 1 and 4 h were transferred to the medium without the drug, no apparent recovery of worm motor activity and survival was seen. In case of worms exposed to praziquantel at the same concentration for 1 and 4 h before replacement of drug-free medium, a well recovery of worm motor activity, looseness of worm body, and reduction or disappearance of blebs along the tegument were observed. Mefloquine also exhibited in vitro effect against 3-h-old and 7- and 14-day-old schistosomula which was similar to that seen in adult worms, but all or parts of worms showed decrease in motor activity or even death (3-h-old and 7-day-old schistosomula) at a lower mefloquine concentration of 5 microg/mL. In 14 day-old schistosomula exposed to praziquantel 1-30 microg/mL, spasmodic contraction and significant decrease in motor activity of the worm body with movement of oral and ventral suckers were observed, but no death of worm was seen during a 3-day incubation period. The results indicate that in vitro mefloquine exhibits a direct killing effect against adult and juvenile S. japonicum which is different from that of praziquantel. Meanwhile, the juvenile schistosomes are more susceptible to mefloquine than the adult ones. Furthermore, the in vitro effect of mefloquine against adult schistosomes is irreversible, while that of praziquantel is reversible.

Caenorhabditis elegans utilizes dauer pheromone biosynthesis to dispose of toxic peroxisomal fatty acids for cellular homoeostasis

Caenorhabditis elegans excretes a dauer pheromone or daumone composed of ascarylose and a fatty acid side chain, the perception of which enables worms to enter the dauer state for long-term survival in an adverse environment. During the course of elucidation of the daumone biosynthetic pathway in which DHS-28 and DAF-22 are involved in peroxisomal beta-oxidation of VLCFAs (very long-chain fatty acids), we sought to investigate the physiological consequences of a deficiency in daumone biosynthesis in C. elegans. Our results revealed that two mutants, dhs-28(tm2581) and daf-22(ok693), lacked daumones and thus were dauer defective; this coincided with massive accumulation of fatty acyl-CoAs (up to 100-fold) inside worm bodies compared with levels in wild-type N2 worms. Furthermore, the deficiency in daumone biosynthesis and the massive accumulation of fatty acids and their acyl-CoAs caused severe developmental defects with reduced life spans (up to 30%), suggesting that daumone biosynthesis is be an essential part of C. elegans homoeostasis, affecting survival and maintenance of optimal physiological conditions by metabolizing some of the toxic non-permissible peroxisomal VLCFAs from the worm body in the form of readily excretable daumones.

Cloning, molecular characterization of a 13-kDa antigen from Schistosoma japonicum, Sj13, a putative salivary diagnosis candidate for Schistosomiasis japonica

Saliva has been suggested as an easily accessible and a noninvasive diagnostic alternative for detection of antibodies. To identify and characterize Schistosoma japonicum (S. japonicum) antigens that are recognized by saliva of infected host, we have used a pool of saliva from infected patients to immunoscreen an egg cDNA library of S. japonicum. The open reading frame of the isolated two clones encodes same protein of 116 amino acids exhibiting 100% identity to an amino acid sequence (AY222893) of S. japonicum in NCBInr database. The protein encoded is inferred a secretory protein with a molecular mass of 13 kDa (Sj13) and shares no homology to any entries in the NCBInr database, demonstrating that Sj13 might be a schistosome-specific protein. Reverse transcriptase polymerase chain reaction, Western blotting, and immunolocalization analysis revealed Sj13 could be detected in cercaria, adult, and egg and was localized to forehead and tegument of cercaria, cell body ("cytons") of adult worm, egg shell, and epidermal plate of miracidium. Furthermore, Sj13 showed a good antigenicity when reacted with saliva or serum from schistosomiasis patients. The recombinant Sj13 (rSj13) expressed and purified from Escherichia coli was applied to detect its specific salivary antibody for schistosomiasis diagnosis by an indirect enzyme linked immunosorbent assay (ELISA). Preliminary laboratory test of 116 subjects, 40 with parasitologically proven S. japonicumm infection, 46 with other infectious diseases, and 30 negative controls exhibited 92.50% sensitivity with saliva/rSj13 and 95.00% with serum/SWAP (P > 0.05). The specificity of the ELISA using saliva/rSj13 was 92.11% versus 85.53% with serum/SWAP (P < 0.05). No direct correlations of anti-Sj13 IgG levels with egg counts in stool were observed in saliva detection. These results suggest that Sj13 specific salivary antibody detection may be useful as an antigen for the salivary diagnosis of schistosomiasis japonica and contribute to epidemiological study of schistosomiasis infection in endemic areas.

Effect of single-dose oral mefloquine on the morphology of adult Schistosoma japonicum in mice

It has been recently documented that the antimalarial drug mefloquine shows in vivo activity against schistosomes. In the present study, we assessed the effect of mefloquine on the morphology of adult Schistosoma japonicum worms. Mice were infected with S. japonicum cercariae for 35 days and then treated with a single 400-mg/kg oral dose of mefloquine. Groups of mice were killed between 24 h and 14 days post-treatment and worms were recovered from the liver and mesenteric veins, fixed in 70% alcohol, stained with acid carmine, and examined under a light microscope. Worms obtained from nontreated mice served as controls. S. japonicum recovered from mice 24 h post-treatment had severely dilated guts and the entire worm body was swollen. Meanwhile, reproductive glands, including the testis, ovary, and vitelline gland, showed signs of degeneration. Damage further progressed, particularly among vitelline glands, which resulted in disturbance of ova formation and cessation of oviposition 3 days post-treatment. Three to 7 days after mefloquine administration, adherence of host leukocytes on the damaged tegument was observed. Our results confirm that mefloquine possesses antischistosomal properties, exhibiting a rapid onset of action and causing extensive morphologic damage to adult S. japonicum.

INDIVIDUAL- AND POPULATION-LEVEL EFFECTS OF THE SYNTHETIC MUSK, HHCB, ON THE DEPOSIT-FEEDING POLYCHAETE, CAPITELLA SP. I

A life table response experiment lasting 120 d was used to investigate the effects of the synthetic polycyclic musk HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8-hexamethylcyclopenta-gamma-2-benzopyrane; 0, 1.5, 26, 123, and 168 mg/kg dry wt sediment) on the life history of the infaunal polychaete Capitella species I. The HHCB exposure showed no detectable effects on adult survival, age at first reproduction, length of the reproductive period, number of broods, individual worm body volumes, or body size-specific egestion rates. In contrast, HHCB significantly affected juvenile survival (>or=123 mg/kg), maturation time (168 mg/kg), total number of eggs produced (>or=26 mg/kg), and brood size (>or=123 mg/kg) and marginally increased time between breeding attempts (>or=26 mg/kg). A declining trend was observed for population growth rate with increasing HHCB concentrations, but differences between the control and exposed groups were not significant. Thus, despite detectable effects of HHCB on individual life-history traits, the results suggest that environmentally realistic concentrations of HHCB are not likely to reduce the growth rate of Capitella sp. I populations.

Sensory Regulation of C. elegans Male Mate-Searching Behavior

How do animals integrate internal drives and external environmental cues to coordinate behaviors? We address this question by studying mate-searching behavior in C. elegans. C. elegans males explore their environment in search of mates (hermaphrodites) and will leave food if mating partners are absent. However, when mates and food coincide, male exploratory behavior is suppressed and males are retained on the food source. We show that the drive to explore is stimulated by male-specific neurons in the tail, the ray neurons. Periodic contact with the hermaphrodite detected through ray neurons changes the male's behavior during periods of no contact and prevents the male from leaving the food source. The hermaphrodite signal is conveyed by male-specific interneurons that are postsynaptic to the rays and that send processes to the major integrative center in the head. This study identifies key parts of the neural circuit that regulates a sexual appetitive behavior in C. elegans.

Fishing lines, time‐delayed guideposts, and other tricks used by developing pharyngeal neurons in Caenorhabditis elegans

The 20 neurons that innervate the Caenorhabditis elegans pharynx form a simple nervous system that develops and operates in near complete isolation from the rest of the worm body and, therefore, offers a manageable degree of complexity for developmental genetics studies. This review discusses the progress that has been made in determining the mechanisms by which 4 of the 20 pharyngeal neurons develop, and emphasizes surprising processes that add to the classic growth cone guidance model which is usually thought to explain how most axons establish their trajectories.

Using Articulated Models for Tracking Multiple C. elegans in Physical Contact

We present a method for tracking and distinguishing multiple C. elegans in a video sequence, including when they are in physical contact with one another. The worms are modeled with an articulated model composed of rectangular blocks, arranged in a deformable configuration represented by a spring-like connection between adjacent parts. Dynamic programming is applied to reduce the computational complexity of the matching process. Our method makes it possible to identify two worms correctly before and after they touch each other, and to find the body poses for further feature extraction. All joint points in our model can be also considered to be the pseudo skeleton points of the worm body. It solves the problem that a previously presented morphological skeleton-based reversal detection algorithm fails when two worms touch each other. The algorithm has many applications in the study of physical interactions between C. elegans.

Mapping technique for biodistribution of elements in a model organism, Caenorhabditis elegans, after exposure to copper nanoparticles with microbeam synchrotron radiation X-ray fluorescence

To investigate the toxicological effects of nanomaterials, experimental studies on the absorption and accumulation in organisms are of broad interest. In the present study, Caenorhabditis elegans (C. elegans) was used as a “model” organism to investigate the bioaccumulation and toxicological effects of engineered copper nanoparticles with a scanning technique of microbeam synchrotron radiation X-ray fluorescence (μ-SRXRF). The adult hermaphrodite is anatomically simple with 959 somatic cells and 1 mm in length. The mapping results of the whole organism indicate that the exposure to copper nanoparticles can result in an obvious elevation of Cu and K levels, and a change of bio-distribution of Cu in nematodes. Accumulation of Cu occurs in the head and at a location 1/3 of the way up the body from the tail compared to the un-exposed control. In contrast, a higher amount of Cu was detected in other portion of worm body, especially in its excretory cells and intestine when exposed to Cu2+. The results compared well with total Cu levels in nematodes, which were 4.10 ± 0.54, 12.32 ± 0.49 and 5.22 ± 0.63 μg g−1 dry weight for the PBS, Cu2+ and Cu nanoparticle groups, respectively, measured by ICP-MS. The nondestructive and multi-elemental μ-SRXRF provides an important tool for mapping the elemental distribution in the whole body of a single tiny nematode at lower levels.

Co-inoculation of Capitella sp. I with its synergistic bacteria enhances degradation of organic matter in organically enriched sediment below fish farms

A polychaete, Capitella sp. I has been shown to degrade organics actively in organically enriched sediment below fish farms. Our aim of the present study is to enhance the biological treatment of sediment by co-inoculation of Capitella sp. I with bacterial isolates that possess high degrading potential for organic matter. We isolated a total of 200 bacterial strains from fecal pellets, burrow lining, worm body, and sediment, and selected six of them for the degradation experiments in the sediment microcosms. With two out of the six isolates, tentatively identified as Vibrio sp. and Vibrio cyclitrophicus by 16SrDNA sequence, we found the TOC reduction rate was stimulated in sediment co-inoculated with the worms and each of the bacteria. In contrast, this was not observed in sediments inoculated only with the worms or the bacterium. These results strongly suggest that co-inoculation of Capitella sp. I with bacteria improves biodegradation.

Uptake of hexanitrohexaazaisowurtzitane (CL-20) by the earthworm Eisenia fetida through dermal contact

The explosive compound hexanitrohexaazaisowurtzitane (CL-20) has been shown to cause both lethal and sublethal (reproductive and neurotoxic) effects in exposed oligochaetes. However, whether worms take up CL-20 and how much CL-20 enters worm bodies leading to toxicity (e.g., lethality) remain to be determined. In the present study, we used high performance liquid chromatography (HPLC) and radiolabeled tracer methods to investigate the CL-20 uptake in the whole worm body after contact exposures. Worms (Eisenia fetida) were exposed to filter paper spiked with non-radioactive or [U-14C]-labeled CL-20 for 1–3 d. The radiolabeled tracer method allowed us to detect the parent compound and transformation products in worms exposed to as low as 0.04 μg CL-20 cm−2 of filter paper. The HPLC method without radiolabeled tracer was far less sensitive with a detection limit of 2.17 μg CL-20 cm−2. Using the radiolabeled tracer, we were able to demonstrate that the worm body concentration linearly correlated to the filter paper concentration ≤0.34 μg cm−2 (r=0.94) if no breakdown products are assumed. At higher concentrations, the body concentration increased slowly and saturated at around 11 μg g−1 dry mass resulting in an estimated lethal critical body burden of 10–15 μg CL-20 g−1 dry mass. These findings demonstrate that CL-20 or potential transformation products are taken into the earthworm body through dermal contact. This information should prove valuable in assessing the bioaccumulation potential and ecological risks of CL-20.

Survivorship and tube growth of reef‐building Serpula vermicularis (Polychaeta: Serpulidae) in two Scottish sea lochs

Abstract In the UK, reef formation by the tubicolous polychaete Serpula vermicularis L. has been recorded in only two sea lochs in Argyll, west Scotland. Serpula vermicularis aggregations are now confined to Loch Creran, those in Loch Sween having died out for unknown reasons. Survivorship and tube extension rates were measured in situ in order to compare habitat quality of the two sea lochs and to determine the feasibility of artificial restoration of Loch Sween reefs using stock translocated from Loch Creran. After labelling and measurement, clusters of inhabited tubes collected from Loch Creran were re‐planted at two sites in Loch Sween and two in Loch Creran in July 2004, and monitored at intervals before recovery and remeasurement in July 2005. In Loch Sween the tube clusters gradually disappeared over the monitoring period. Only remnants were left by May 2005 and no growth data were obtained. In Loch Creran 76% of the labelled tubes were relocated. Confirmed mortality over the year was 5.3% and mean tube extension rate was 33 mmy−1. There was no significant difference in tube growth between the two Loch Creran sites and inter‐individual differences accounted for most of the variability in the data. Individual tube extension declined significantly with worm body mass but mean extension showed no relationship to total worm biomass in each cluster. Annual tube extension rate in Loch Creran was low in comparison with literature data from other serpulids, suggesting that tube growth is strongly seasonal. The 10‐month persistence of some living worms in Loch Sween suggests that there is no physiological barrier to survival of stock translocated from Loch Creran but in situ video monitoring would be necessary to determine the cause of tube disappearance. Copyright © 2007 John Wiley &amp; Sons, Ltd.

The twisted pharynx phenotype in C. elegans

BackgroundThe pharynx of C. elegans is an epithelial tube whose development has been compared to that of the embryonic heart and the kidney and hence serves as an interesting model for organ development. Several C. elegans mutants have been reported to exhibit a twisted pharynx phenotype but no careful studies have been made to directly address this phenomenon. In this study, the twisting mutants dig-1, mig-4, mnm-4 and unc-61 are examined in detail and the nature of the twist is investigated.ResultsWe find that the twisting phenotype worsens throughout larval development, that in most mutants the pharynx retains its twist when dissected away from the worm body, and that double mutants between mnm-4 and mutants with thickened pharyngeal domains (pha-2 and sma-1) have less twisting in these regions. We also describe the ultrastructure of pharyngeal tendinous organs that connect the pharyngeal basal lamina to that of the body wall, and show that these are pulled into a spiral orientation by twisted pharynges. Within twisted pharynges, actin filaments also show twisting and are longer than in controls. In a mini screen of adhesionmolecule mutants, we also identified one more twisting pharynx mutant, sax-7.ConclusionDefects in pharyngeal cytoskeleton length or its anchor points to the extracellular matrix are proposed as the actual source of the twisting force. The twisted pharynx is a useful and easy-to-score phenotype for genes required in extracellular adhesion or organ attachment, and perhaps forgenes required for cytoskeleton regulation.

Proteomic analysis of the shistosome tegument and its surface membranes

The tegument surface of the adult schistosome, bounded by a normal plasma membrane overlain by a secreted membranocalyx, holds the key to understanding how schistosomes evade host immune responses. Recent advances in mass spectrometry (MS), and the sequencing of the Schistosoma mansoni transcriptome/genome, have facilitated schistosome proteomics. We detached the tegument from the worm body and enriched its surface membranes by differential extraction, before subjecting the preparation to liquid chromatography-based proteomics to identify its constituents. The most exposed proteins on live worms were labelled with impearmeant biotinylation reagents, and we also developed methods to isolate the membranocalyx for analysis. We identified transporters for sugars, amino acids, inorganic ions and water, which confirm the importance of the tegument plasma membrane in nutrient acquisition and solute balance. Enzymes, including phosphohydrolases, esterases and carbonic anhydrase were located with their catalytic domains external to the plasma membrane, while five tetraspanins, annexin and dysferlin were implicated in membrane architecture. In contrast, few parasite proteins could be assigned to the membranocalyx but mouse immune response proteins, including three immunoglobulins and two complement factors, were detected, plus host membrane proteins such as CD44, integrin and a complement regulatory protein, testifying to the acquisitive properties of the secreted bilayer.

Immunoreactivity to molluskan neuropeptides in the central and stomatogastric nervous systems of the earthworm, Lumbricus terrestris L.

Polyclonal antisera against two related command neuropeptides (CNP2 and CNP4) described in neurons of the terrestrial snail Helix were used in a study of the nervous system of the earthworm Lumbricus. The CNP-like peptides belong to the same neuropeptide subfamily and bear a C-terminal signature sequence Tyr-Pro-Arg-X. The distribution patterns of immunoreactive (IR) neurons were studied in the central nervous system (CNS), skin, and stomatogastric nervous system of the earthworm. IR neurons were found in all CNS ganglia, the patterns being similar for both antibodies used. Several clusters of IR cells were observed in the cerebral and subesophageal ganglia. In the ventral cord ganglia, the number of IR cells decreased in the rostro-caudal direction, and the IR cells sent their fibers mostly into the median fiber bundle. Segmental nerves contained no IR fibers. After injury of the worm body, the number of IR neurons in the CNS significantly increased. In the skin, IR sensory neurons were present in sensory buds. The stomatogastric ganglia only contained IR fibers. Numerous scattered IR neurons were found in the inner subepithelial layer of the esophagus and formed the enteric plexus in which the cell bodies displayed a segmentally repeated pattern. Possible involvement of CNP-like-IR neurons in central integratory processes, sensory processes, and the regulation of feeding is discussed.