The Origin of Parasitism Gene in Nematodes: Evolutionary Analysis through the Construction of Domain Trees

Inferring evolutionary history of parasitism genes is important to understand how evolutionary mechanisms affect the occurrences of parasitism genes. In this study, we constructed multiple domain trees for parasitism genes and genes under free-living conditions. Further analyses of horizontal gene transfer (HGT)-like phylogenetic incongruences, duplications, and speciations were performed based on these trees. By comparing these analyses, the contributions of pre-adaptations were found to be more important to the evolution of parasitism genes than those of duplications, and pre-adaptations are as crucial as previously reported HGTs to parasitism. Furthermore, speciation may also affect the evolution of parasitism genes. In addition, Pristionchus pacificus was suggested to be a common model organism for studies of parasitic nematodes, including root-knot species. These analyses provided information regarding mechanisms that may have contributed to the evolution of parasitism genes

A new enteric nematode of Camallanus (Nematoda : Camallanidae) from Jiyu Island of Amoy (Taiwan Strait)

yA new enteric nematode, Camallanus jiyuensis n. sp., is described from the intestine of the shokihaze goby, Tridentiger barbatus (Gunther, 186 1), collected from the beach of Jiyu Island, Amoy, southeast of China. The new species differs from its congeners mainly in the following combination of characters. The body is rather small in size, with 2 squarish, chitinized thickenings on the anterior border of the buccal capsule. The prongs of the trident are unequal. The nerve ring is near the posterior end of tridents. Cervical papillae are located in the middle of muscular esophagus. The excretory pore is located in the posterior third of muscular esophagus. Twelve pairs of pedunculate caudal papillae are present, of which 7 pairs are preanal and 5 are postanal. Spicules are similar. but subequal in length; the right and the left account for 9.8% and 8.9% of body length, respectively. The vulva does not protrude conspicuously from body surface and is located postequatorially

Description of a new ascarid species in elasmobranchs from Taiwan Strait

A new ascarid of elasmobranchs, Terranova amoyensis sp. n., is described from the intestine of the red stringray, Dasyatis akajei (Muller and Henle), from Taiwan Strait. This is the second report from this genus with a gubernaculum in fish. The new species differs from its congeners mainly in the following combination of characters: the 3 lips are unequal in size and different in shape, i.e., the subventral lips are asymmetric bilaterally and larger than the dorsal lip; the latter lip is bilaterally symmetrical. The ventriculus is spherical, and the cecum is short relative to the esophagus. Spicules are unequal in size, 1.48 rum long for the right spicule and 1.34 mm for the left spicule, or 4.3 and 3.9% of body length, respectively. Nineteen pairs of caudal sessile papillae (excluding phasmids) are present, of which 13 pairs are precloacal; pairs 14 and 15 lie close together on either side of the cloaca, composing ad-cloacal papillae (the pair near the tail end are twins). The remaining 4 pairs of postcloacal papillae form a group near the tail tip (pair 18 also twins and near the phasmids). The gubernaculum is I-shaped. The excretory pore is located on top of a coniform prominence whose location is just behind or between the bases of the 2 subventral lips. The vulva is prominent at one-third of the anterior part of the body; the distance from the vulva opening to the anterior body end is 17.4 mm (13.61-21.41), 26.8% (25.14-28.93%) of the body length

Improved Marine Predator Algorithm for Wireless Sensor Network Coverage Optimization Problem

A wireless sensor network (WSN) is a distributed network system composed of a great many sensor nodes that rely on self-organization. The random deployment of WSNs in city planning often leads to the problem of low coverage of monitoring areas. In the construction of smart cities in particular, a large number of sensor nodes need to be deployed to maintain the reception, processing, and transmission of data throughout the city. However, the uneven distribution of nodes can cause a lot of wasted resources. To solve this problem, this paper proposes a WSN coverage optimization model based on an improved marine predator algorithm (IMPA). The algorithm introduces a dynamic inertia weight adjustment strategy in the global exploration and local exploitation stages of the standard marine predator algorithm to balance the exploration and exploitation capabilities of the algorithm and improve its solution accuracy. At the same time, the improved algorithm uses a multi-elite random leading strategy to enhance the information exchange rate between population individuals and improve the algorithm’s ability to jump out of the local optimum. The optimization experiment results of 11 benchmark test functions and part of the CEC2014 test functions show that the optimization performance of the improved algorithm is significantly better than the standard marine predator algorithm and other algorithms in the literature. Finally, the improved algorithm is applied to the WSN coverage optimization problem. The simulation results demonstrate that the IMPA has a better coverage rate than other metaheuristic algorithms and other improved algorithms in the literature for solving the WSN coverage optimization problem

Angiostrongylus cantonensis cathepsin B-like protease (Ac-cathB-1) is involved in host gut penetration

Although the global spread of the emerging zoonosis, human angiostrongyliasis, has attracted increasing attention, understanding of specific gene function has been impeded by the inaccessibility of genetic manipulation of the pathogen nematode causing this disease, Angiostrongylus cantonensis. Many parasitic proteases play key roles in host-parasite interactions, but those of A. cantonensis are always expressed as the inactive form in prokaryotic expression systems, thereby impeding functional studies. Hence, a lentiviral system that drives secreted expression of target genes fused to a Myc-His tag was used to obtain recombinant Ac-cathB-1 with biological activity. Although this class of proteases was always reported to function in nutrition and immune evasion in parasitic nematodes, recombinant Ac-cathB-1 was capable of hydrolysis of fibronectin and laminin as well as the extracellular matrix of IEC-6 monolayer, so that the intercellular space of the IEC-6 monolayer increased 5.15 times as compared to the control, while the shape of the adherent cells partly rounded up. This suggests a probable role for this protease in intestinal epithelial penetration. The inhibition of Ac-cathB-1 enzymatic activity with antiserum partly suppressed larval penetration ability in the isolated intestine. Thus, an effective system for heterologous expression of parasite proteases is presented for studying gene function in A. cantonensis; and Ac-cathB-1 was related to larval penetration ability in the host small intestine

PCR assay for the cell-free copro-DNA detection of Angiostrongylus cantonensis in rat faeces

Science and Technology Planning Project of Fujian Province [2008N2005]; Natural Science Foundation of Fujian Province [2010J01229]; National Foundation for Fostering Talents of Basic Science [J1030626]To facilitate improved detection of the first stage larvae (L1) of Angiostrongylus cantonensis from rat faeces, a TaqMan (R) probe real-time PCR method for the detection in situ was developed targeting the second internal transcribed region of the ribosomal DNA (ITS2) of A. cantonensis. The assay was capable of detecting a single L1 in a grain of fresh faeces (weight 320 +/- 125 mg) from the experimental infected Sprague-Dawley rats, and the method can also detect cell-free copro-DNA from positive faeces placed for up to 12 months at ambient environment. The present study exhibited a high level of specificity for A. cantonensis, with no fluorescence signals were observed in reference control consisting of four parasite species commonly found in the intestine of rat. This approach can overcome the limitations of DNA-based identification that faecal materials should be stored in 70% ethanol or kept as frozen samples for further tests, and thus it might be suitable and feasible for the detection of target DNA in faecal materials preserved at ambient temperature, but the detecting efficiency will depend on the amount of DNA in the samples and the time placed for the samples due to DNA degradation. (C) 2011 Elsevier B.V. All rights reserved

Comparative transcriptomic analysis of two important life stages of Angiostrongylus cantonensis: fifth-stage larvae and female adults

Abstract The mechanisms involved in the fast growth of Angiostrongylus cantonensis from fifth-stage larvae (L5) to female adults and how L5 breaks through the blood-brain barrier in a permissive host remain unclear. In this work, we compared the transcriptomes of these two life stages to identify the main factors involved in the rapid growth and transition to adulthood. RNA samples from the two stages were sequenced and assembled de novo. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses of 1,346 differentially expressed genes between L5 and female adults was then undertaken. Based on a combination of analytical results and developmental characteristics, we suggest that A. cantonensis synthesizes a large amount of cuticle in L5 to allow body dilatation in the rapid growth period. Products that are degraded via the lysosomal pathway may provide sufficient raw materials for cuticle production. In addition, metallopeptidases may play a key role in parasite penetration of the blood-brain barrier during migration from the brain. Overall, these results indicate that the profiles of each transcriptome are tailored to the need for survival in each developmental stage