PHYLOGEOGRAPHY OF BAYLISASCARIS PROCYONIS (RACCOON ROUNDWORM) IN NORTH AMERICA

Sequences of the mitochondrial cytochrome c oxidase 1 (COI) gene of 115 Baylisascaris procyonis individuals from 13 U.S. states and 1 Canadian province were obtained from 44 raccoon hosts to assess genetic variation and geographic structure. The maximum genetic distance between individuals was low (1.6%), consistent with a single species. Moderate COI haplotype (h = 0.60) and nucleotide (π = 0.0053) diversity were found overall. Low haplotype diversity was found among samples east of the Mississippi River (h = 0.036), suggesting that historical growth and expansion of raccoon populations in this region could be responsible for high parasite gene flow or a selective sweep of B. procyonis mtDNA. There was low genetic structure (average Φst = 0.07) for samples east of the continental divide, but samples from Colorado showed higher diversity and differentiation from midwestern and eastern samples. There was marked genetic structure between samples from east and west of the continental divide, with no haplotypes shared between these regions. There was no significant isolation by distance among any of these geographic samples. The phylogeographic patterns for B. procyonis are similar to genetic results reported for their raccoon definitive hosts. The phylogeographic divergence of B. procyonis from east and west of the continental divide may involve vicariance resulting from Pleistocene glaciation and associated climate variation.

The morphological and molecular characterization of Baylisascaris devosi Sprent, 1952 (Ascaridoidea, Nematoda), collected from Pine marten (Martes martes) in Iran

Background

Baylisascaris devosi is an intestinal nematode found in several carnivores including fisher, wolverine, Beech marten, American marten and sable in different parts of the world, but this nematode has not been reported from Pine marten. Therefore, this study aimed to identify Baylisascaris isolated from a Pine marten in Iran using morphological and molecular approaches.

Methods

Specimens of B. devosi were collected from one road-killed Pine marten in northern Iran. Morphological features were evaluated using scanning electron microscopy, energy dispersive x-ray analysis and ion sectioning. The molecular characterization was carried out using partial Cox1, LSU rDNA and ITS-rDNA genes.

Results

The nematodes isolated from the Pine marten were confirmed to be B. devosi based on the morphological features and the sequence of ribosomal and mitochondrial loci. X-ray scans (EDAX) were completed on gallium cut structures (papillae, eggs, male spike and mouth denticles) of B. devosi using a dual-beam scanning electron microscope. The male spike and mouth denticles had a high level of hardening elements (Ca, P, S), helping to explain the chemical nature and morphology of the worm. Based on these genetic marker analyses, our sequence had the greatest similarity with Russian B. devosi isolated from sable.

Conclusions

In this study, to our knowledge, the occurrence of B. devosi infection in Pine marten is reported for the first time. Molecular analysis showed that these three genes are suitable molecular markers for identification and inferring phylogenetic relationships of Baylisascaris species. Furthermore, the high divergence of Cox1 between Baylisascaris species indicates that Cox1 could be used for their phylogenetic and taxonomic studies.

First record of natural Baylisascaris transfuga (Ascaridoidea, Nematoda) infection in wild rodents

The intestinal parasitic nematode, Baylisascaris transfuga, was recorded in wild rodents for the first time. Representatives of four murid species (15 Myodes rufocanus, 10 M. rutilus, 3 M. glareolus and 27 Microtus oeconomus) were collected in the White Sea coastal habitats in the south of the Kola Peninsula, Russia in July 2015 and examined for parasites. Encapsulated nematode larvae were detected in the mesentery and the large intestine wall of one grey-sided vole (M. rufocanus) and one tundra vole (M. oeconomus). Based on morphology, the larvae were identified as belonging to the genus Baylisascaris Sprent 1968. The partial 18S rDNA sequence of the larvae from the voles was obtained and fully corresponded to the sequence of Baylisascaris transfuga in the NCBI GenBank. The ITS rDNA and CoxI mtDNA sequences these larvae were also similar to the respective B. transfuga sequences in GenBank. The presence of B. transfuga in wild rodents suggests that rodents can participate in the B. transfuga life cycle.

Molecular phylogenetics and species-level systematics of Baylisascaris

Nucleotide sequences representing nine genes and five presumptive genetic loci were used to infer phylogenetic relationships among seven Baylisascaris species, including one species with no previously available molecular data. These genes were used to test the species status of B. procyonis and B. columnaris using a coalescent approach. Phylogenetic analysis based on combined analysis of sequence data strongly supported monophyly of the genus and separated the species into two main clades. Clade 1 included B. procyonis, B. columnaris, and B. devosi, species hosted by musteloid carnivores. Clade 2 included B. transfuga and B. schroederi from ursids, B. ailuri, a species from the red panda (a musteloid), and B. tasmaniensis from a marsupial. Within clade 2, geographic isolates of B. transfuga, B. schroederi (from giant panda), and B. ailuri formed a strongly supported clade. In certain analyses (e.g., some single genes), B. tasmaniensis was sister to all other Baylisascaris species rather than sister to the species from ursids and red panda. Using one combination of priors corresponding to moderate population size and shallow genetic divergence, the multispecies coalescent analysis of B. procyonis and B. columnaris yielded moderate support (posterior probability 0.91) for these taxa as separate species. However, other prior combinations yielded weak or no support for delimiting these taxa as separate species. Similarly, tree topologies constrained to represent reciprocal monophyly of B. columnaris and B. procyonis individuals (topologies consistent with separate species) were significantly worse in some cases, but not others, depending on the dataset analyzed. An expanded analysis of SNPs and other genetic markers that were previously suggested to distinguish between individuals of B. procyonis and B. columnaris was made by characterization of additional individual nematodes. The results suggest that many of these SNPs do not represent fixed differences between nematodes derived from raccoon and skunk hosts.

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A phylogenetic hypothesis for Baylisascaris species was produced using nine genes.

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Genetic data was generated for two new species- B. devosi and B. tasmaniensis.

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Baylisascaris devosi and B. tasmaniensis were part of a monophyletic Baylisascaris.

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B. procyonis (raccoon) and B. columnaris (skunk) could not be reliably distinguished.

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Established SNPs may not be diagnostic for Baylisascaris from raccoons and skunks.

Parasites of the Giant Panda: A Risk Factor in the Conservation of a Species

The giant panda, with an estimated population size of 2239 in the world (in 2015), is a global symbol of wildlife conservation that is threatened by habitat loss, poor reproduction and limited resistance to some infectious diseases. Of these factors, some diseases caused by parasites are considered as the foremost threat to its conservation. However, there is surprisingly little published information on the parasites of the giant panda, most of which has been disseminated in the Chinese literature. Herein, we review all peer-reviewed publications (in English or Chinese language) and governmental documents for information on parasites of the giant pandas, with an emphasis on the intestinal nematode Baylisascaris schroederi (McIntosh, 1939) as it dominates published literature. The purpose of this chapter is to: (i) review the parasites recorded in the giant panda and describe what is known about their biology; (ii) discuss key aspects of the pathogenesis, diagnosis, treatment and control of key parasites that are reported to cause clinical problems and (iii) conclude by making some suggestions for future research. This chapter shows that we are only just 'scratching the surface' when it comes to parasites and parasitological research of the giant panda. Clearly, there needs to be a concerted research effort to support the conservation of this iconic species.