UsingDNAbarcoding to link cystacanths and adults of the acanthocephalanPolymorphus brevisin central Mexico

Abstract

In parasitic organisms, particularly helminths, the usage of the mitochondrial cytochrome c oxidase subunit I gene as the standard DNA barcoding region for species identification and discovery has been very limited. Here, we present an integrated study, based on both DNA barcoding and morphological analyses, for acanthocephalans belonging to the genus Polymorphus, whose larvae (cystacanths) are commonly found in the mesentery of freshwater fishes, while adults are found in the intestine of fish-eating birds. The alpha taxonomy of parasitic helminths is based on adult morphological traits, and because of that larval forms cannot be identified to species level based on morphology alone. DNA barcoding offers an alternative tool for linking larval stages of parasitic organisms to known adults. We sequenced cystacanths collected from freshwater fishes in localities across central Mexico and adults obtained from fish-eating birds, to determine whether they were conspecific. To corroborate the molecular results, we conducted a morphometric analysis with 'Proboscis profiler', which is a software tool developed to detect heterogeneity in morphologically similar acanthocephalans based on the multivariate statistical analysis of proboscis hook dimensions. Both sources of information indicate that cystacanths infecting freshwater fishes in central Mexico belong to a single species, Polymorphus brevis.

Molecular and morphological evidence for three species of Diplostomum (Digenea: Diplostomidae), parasites of fishes and fish-eating birds in Spain

“…[1][2][3][4][5]. The mitochondrial cytochrome c oxidase subunit 1 (cox1) barcode region was found to be suitable for this goal as well as for the identification and recognition of cryptic species diversity within Diplostomum [1,6,7].…”

Molecular and morphological evidence for three species of Diplostomum (Digenea: Diplostomidae), parasites of fishes and fish-eating birds in Spain

“…[1-5]. The mitochondrial cytochrome c oxidase subunit 1 ( cox 1) barcode region was found to be suitable for this goal as well as for the identification and recognition of cryptic species diversity within Diplostomum [1,6,7].…”

Parasite life-cycle studies: a plea to resurrect an old parasitological tradition

“…This approach has been used frequently to either elucidate life cycles, or confirm suspected life cycles, in particular helminth species (e.g. Bartoli et al, 2000;Pina et al, 2009;Randhawa, 2011;Li et al, 2012;Alcántar-Escalera et al, 2013;Jezewski et al, 2013;Selbach et al, 2015;Huston et al, 2016;Gonchar & Galaktionov, 2017). In fact, Blasco-Costa et al (2016) have shown that from 2011 to 2015, the use of genetic data in trematode life-cycle studies has been the most common approach (approximately 65% of all trematode life-cycle studies), making this the method of choice to elucidate and/or confirm helminth life cycles.…”