scholarly journals Genomics of the Parasitic Nematode Ascaris and Its Relatives

Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 493
Author(s):  
Jianbin Wang
Keyword(s):  
Small Rna ◽  
Drug Targets ◽  
Sex Chromosome ◽  
Model Organisms ◽  
Parasitic Nematodes ◽  
Embryonic Cells ◽  
Genomic Resources ◽  
Dna Elimination ◽  
Parasite Relationship ◽  
Host Parasite

Nematodes of the genus Ascaris are important parasites of humans and swine, and the phylogenetically related genera (Parascaris, Toxocara, and Baylisascaris) infect mammals of veterinary interest. Over the last decade, considerable genomic resources have been established for Ascaris, including complete germline and somatic genomes, comprehensive mRNA and small RNA transcriptomes, as well as genome-wide histone and chromatin data. These datasets provide a major resource for studies on the basic biology of these parasites and the host–parasite relationship. Ascaris and its relatives undergo programmed DNA elimination, a highly regulated process where chromosomes are fragmented and portions of the genome are lost in embryonic cells destined to adopt a somatic fate, whereas the genome remains intact in germ cells. Unlike many model organisms, Ascaris transcription drives early development beginning prior to pronuclear fusion. Studies on Ascaris demonstrated a complex small RNA network even in the absence of a piRNA pathway. Comparative genomics of these ascarids has provided perspectives on nematode sex chromosome evolution, programmed DNA elimination, and host–parasite coevolution. The genomic resources enable comparison of proteins across diverse species, revealing many new potential drug targets that could be used to control these parasitic nematodes.

Changes in gene expression during stimulation and hatching of the potato cyst nematode Globodera rostochiensis

Parasitology ◽  
1997 ◽  
Vol 114 (3) ◽  
pp. 309-315 ◽  
Author(s):  
J. T. JONES ◽  
L. ROBERTSON ◽  
R. N. PERRY ◽  
W. M. ROBERTSON
Keyword(s):  
Gene Expression ◽  
Globodera Rostochiensis ◽  
Cyst Nematode ◽  
Potato Cyst Nematode ◽  
Parasitic Nematodes ◽  
Examine Gene Expression ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Stage Juvenile ◽  
Host Parasite

The potato cyst nematode (PCN) Globodera rostochiensis, like other parasitic nematodes, needs to synchronize its life-cycle with that of its host. This synchrony is achieved by the invasive-stage juvenile remaining dormant within its egg until stimulated to hatch by the presence of root diffusates of its host. Root diffusates may induce changes in gene expression in PCN, some of which may be important in the transition to a parasitic mode of existence. We have used a range of techniques including differential display to examine gene expression during stimulation and hatching of PCN. We find that few changes in gene expression appear to be induced directly by root diffusates. Instead, changes in gene expression seem to occur during or immediately after the hatching process. These results are discussed in the context of the host–parasite relationship.

scholarly journals Symbiosis of the Millipede Parasitic Nematodes Rhigonematoidea and Thelastomatoidea with Evolutionary Different Origins

2020 ◽  
Author(s):  
Seiya Nagae ◽  
Kazuki Sato ◽  
Tsutomu Tanabe ◽  
Koichi Hasegawa
Keyword(s):  
Evolutionary Biology ◽  
Parasitic Nematode ◽  
Nematode Species ◽  
Parasitic Nematodes ◽  
Infection Prevalence ◽  
Broad Host Range ◽  
Parasite Relationship ◽  
Nematode Diversity ◽  
Different Origins ◽  
Host Parasite

Abstract BackgroundHow various host-parasite combinations have been established is an important question in evolutionary biology. We have previously described two nematode species, Rhigonema naylae and Travassosinema claudiae, which are parasites of the Xystodesmidae millipede Parafontaria laminata in Aichi Prefecture, Japan. Rhigonematoidea belongs to the infraorder Rhigonematomorpha and is phylogenetically close to the Ascaridomorpha, which includes the roundworm parasite in animals. Thelastomatoidea spp. belong to the infraorder Oxyuridomorpha, which comprises a wide variety of parasites in many vertebrates and invertebrates. These nematodes were isolated together with high prevalence; however, the phylogenetic, evolutionary, and ecological relationships between these two parasitic nematodes and between host-parasites are not well known.ResultsWe collected nine species (11 isolates) of Xystodesmidae millipede from seven different locations in Japan and found that all species were co-infected with the parasitic nematodes Rhigonematoidea spp. and Thelastomatoidea spp. Rhigonematoidea spp. is exclusively a millipede parasite, and combinations of parasitic nematode groups and host genera seem to be fixed, supporting the hypothesis of their co-speciation. Intriguingly, Thelastomatoidea spp. were isolated, and the host-parasite relationship was not clarified, clearly indicating the broad host range of these nematode groups. Although the infection prevalence and population of Rhigonematoidea spp. were higher than those of Thelastomatoidea spp., these parasites were not competitive. The population of Rhigonematoidea spp. was not negatively affected by co-infection with Thelastomatoidea spp.ConclusionsPhylogenetic analysis supported our hypothesis that, during the evolution of parasitic nematode diversity in millipedes, the Rhigonematoidea spp. first established relationships with millipedes and were followed by the Thelastomatoidea spp.. The ancestor of the latter nematode might have moved from other host arthropods such as cockroaches.

The influence of the actionmycete,Pasteuria penetrans, on the host–parasite relationship of the plant-parasitic nematode,Meloidogyne javanica

Parasitology ◽  
1986 ◽  
Vol 93 (3) ◽  
pp. 571-580 ◽  
Author(s):  
A. F. Bird
Keyword(s):  
Giant Cells ◽  
Parasitic Nematodes ◽  
Pasteuria Penetrans ◽  
Root Knot Nematode ◽  
Plant Host ◽  
Parasite Relationship ◽  
Short Time ◽  
Host Parasite ◽  
Relationship Of ◽  
Plant Parasitic

SUMMARYThe actinomycete,Pasteuria penetrans, is a specific endoparasite of various plant-parasitic nematodes. When parasitizing the root-knot nematode (Meloidogyne javanical) the nematode's capacity to reproduce is destroyed and feeding on and stimulation of the plant host are unaffected even though the bulbous body of the female nematode becomes filled with spores. Parasitism by the actinomycete does not alter the rate of growth in the early stages of nematode development although the non-parasitized female grows more rapidly than the parasitized one for a short time immediately after the final moult.Pasteuriadid not invade or inactivate the anterior oesophageal region of the femaleMeloidogyneor influence the morphology of the giant cells induced by these nematodes in their hosts' roots. The influence of this parasite on the developmental physiology of its nematode host is discussed.

scholarly journals Environmental RNAi pathways in the two-spotted spider mite

BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Mosharrof Mondal ◽  
Jacob Peter ◽  
Obrie Scarbrough ◽  
Alex Flynt
Keyword(s):  
Gene Expression ◽  
Small Rna ◽  
Spider Mite ◽  
Genetic Manipulation ◽  
Model Organisms ◽  
Rnai Pathway ◽  
Plant Host ◽  
Rnai Technology ◽  
Two Spotted Spider Mite ◽  
Multicellular Organisms

Abstract Background RNA interference (RNAi) regulates gene expression in most multicellular organisms through binding of small RNA effectors to target transcripts. Exploiting this process is a popular strategy for genetic manipulation and has applications that includes arthropod pest control. RNAi technologies are dependent on delivery method with the most convenient likely being feeding, which is effective in some animals while others are insensitive. The two-spotted spider mite, Tetranychus urticae, is prime candidate for developing RNAi approaches due to frequent occurrence of conventional pesticide resistance. Using a sequencing-based approach, the fate of ingested RNAs was explored to identify features and conditions that affect small RNA biogenesis from external sources to better inform RNAi design. Results Biochemical and sequencing approaches in conjunction with extensive computational assessment were used to evaluate metabolism of ingested RNAs in T. urticae. This chelicerae arthropod shows only modest response to oral RNAi and has biogenesis pathways distinct from model organisms. Processing of synthetic and plant host RNAs ingested during feeding were evaluated to identify active substrates for spider mite RNAi pathways. Through cataloging characteristics of biochemically purified RNA from these sources, trans-acting small RNAs could be distinguished from degradation fragments and their origins documented. Conclusions Using a strategy that delineates small RNA processing, we found many transcripts have the potential to enter spider mite RNAi pathways, however, trans-acting RNAs appear very unstable and rare. This suggests potential RNAi pathway substrates from ingested materials are mostly degraded and infrequently converted into regulators of gene expression. Spider mites infest a variety of plants, and it would be maladaptive to generate diverse gene regulators from dietary RNAs. This study provides a framework for assessing RNAi technology in organisms where genetic and biochemical tools are absent and benefit rationale design of RNAi triggers for T.urticae.

Susceptibilities of Various Snail Intermediate Hosts of Schistosoma mansoni to Different Strains of the Parasite

1965 ◽  
Vol 39 (4) ◽  
pp. 363-376 ◽  
Author(s):  
M.F.A. Saoud
Keyword(s):  
Puerto Rico ◽  
Schistosoma Mansoni ◽  
Intermediate Hosts ◽  
Considerable Evidence ◽  
The Past ◽  
Host Parasite Relationship ◽  
Parasite Relationship ◽  
Different Strains ◽  
Host Parasite ◽  
Comprehensive Studies

In the past two decades, considerable evidence has accumulated in the literature about the differences in the susceptibility of various intermediate hosts of Schistosoma mansoni to different strains of the parasite. Comprehensive studies on this aspect of host-parasite relationship have been published by Files & Cram (1949), Abdel-Malek (1950) and Files (1951). The results of more recent studies have been reported by Wright (1962) and Saoud (1964).In the present paper, the writer has studied the susceptibility of four intermediate hosts of S. mansoni from Brazil, Puerto Rico, Egypt and Tanganyika to some strains of the parasite.

Certain aspects of the host-parasite relationship ofNematospiroides dubius(Baylis). II. The effect of sex on experimental infections in the rat (an abnormal host)

Parasitology ◽  
1961 ◽  
Vol 51 (3-4) ◽  
pp. 499-510 ◽  
Author(s):  
Colin Dobson
Keyword(s):  
Male Rats ◽  
Male Rat ◽  
Normal Male ◽  
Female Rat ◽  
Castrate Male ◽  
Parasite Relationship ◽  
Nematospiroides Dubius ◽  
Resistance To Infection ◽  
Host Parasite ◽  
The Relationship

1. The male rat is more susceptible to infections ofNematospiroides dubiusthan the female. As the rat grows older the resistance of the female rat to infection increases at a greater rate than that of the male.2. The course of the infection is modified by the sex of the host.3. More larvae penetrated the intestinal mucosa to encyst in the male than in the female. More larvae, however, formed cysts in the female than in the male rat by the fifth day.4. The male harboured more adult worms than the female rat, although this difference was not significant in the immature animals.5. The sex resistance of the rat toN. dubiusinfections was removed by bilateral gonadectomy. Castration decreased the susceptibility of the male rat, while spaying increased it in the female compared with the susceptibility in the respective normal hosts.6. Subsequent replacement of the homologous sex hormone in the gonadectomized rat restores the sex resistance, and may even increase it (particularly in the immature animals). Oestradiol increased the resistance of the spayed female rat, while testosterone increased the susceptibility of the castrate male rat to infection.7. Oestradiol implanted in castrate male rats increased the resistance of these hosts to a greater level than was shown in the normal male rat.8. The rat shows a marked age resistance over which the sex resistance is superimposed.9. The relationship between the sex of the host and its resistance to infection is discussed.This work was done during the tenure of a Department of Scientific and Industrial Research Studentship. My thanks are due to Dr E. T. B. Francis for his helpful and critical supervision and to Professor I. Chester Jones, in whose department the work was done, for the facilities he provided.

scholarly journals Prospects of Using High-Throughput Proteomics to Underpin the Discovery of Animal Host–Nematode Interactions

Pathogens ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 825
Author(s):  
Tao Wang ◽  
Robin Gasser
Keyword(s):  
Mass Spectrometry ◽  
High Throughput ◽  
Anthelmintic Resistance ◽  
Nematode Species ◽  
Economic Losses ◽  
Future Research ◽  
Parasitic Nematodes ◽  
Public Health Burden ◽  
Host Parasite Interactions ◽  
Host Parasite

Parasitic nematodes impose a significant public health burden, and cause major economic losses to agriculture worldwide. Due to the widespread of anthelmintic resistance and lack of effective vaccines for most nematode species, there is an urgent need to discover novel therapeutic and vaccine targets, informed through an understanding of host–parasite interactions. Proteomics, underpinned by genomics, enables the global characterisation proteins expressed in a particular cell type, tissue and organism, and provides a key to insights at the host–parasite interface using advanced high-throughput mass spectrometry-based proteomic technologies. Here, we (i) review current mass-spectrometry-based proteomic methods, with an emphasis on a high-throughput ‘bottom-up’ approach; (ii) summarise recent progress in the proteomics of parasitic nematodes of animals, with a focus on molecules inferred to be involved in host–parasite interactions; and (iii) discuss future research directions that could enhance our knowledge and understanding of the molecular interplay between nematodes and host animals, in order to work toward new, improved methods for the treatment, diagnosis and control of nematodiases.

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