Browsing by Author "Martínez-Rojas, Rosa"

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A New Species of Mymarothecium tantaliani n. sp (Monogenea: Dactylogiridae) in the Gills of Gamitana Colossoma macropomum (Cuvier) from Madre de Dios, Peru
(Springer Science and Business Media LLC, 2020-7-12) Cayulla-Quispe, David; Mondragón-Martínez, Aarón; Rojas-De-Los-Santos, Estrellita; Garcia-Candela, Enrique; Babilonia-Medina, Jorge; Martínez-Rojas, Rosa
Introduction: Members of the genus Mymarothecium Kritsky, Boeger & Jégu, 1996 infect characiform fish in the Amazon River Basin. Although the Peruvian Amazon hosts rich fauna of fish, the taxonomic diversity of parasitic organisms such as Mymarothecium has been few explored. A new species of Mymarothecium in Colossoma macropomum Cuvier, from the southeast of the Peruvian Amazon, is described. Methods: Monogeneans were isolated from gills of C. macropomum, fixed in formaldehyde in 4% solution. For morphological examinations were stained with Gomori’s trichrome and others were clarified with Hoyer’s medium. Results: Mymarothecium is the third species of the genus recorded in C. macropomum. These new species have been characterized by a slightly sigmoid male copulatory organ (MCO) and the accessory piece with sinuous distal rod with hook-shaped process and a bifurcation in the middle part. Furthermore, the anteromedial projection of the ventral rod has a small conspicuous filament in both anchors. Conclusions: With the description of this new species, eight species of Mymarothecium have been reported in fish of the Serrasalmidae family originating in the Amazon. © 2021 Elsevier B.V., All rights reserved.
Complete mitochondrial genome assembly and analysis of a Neotropical lineage of Ligula intestinalis reveals evolutionary and phylogenetic insights
(Springer Science and Business Media LLC, 2026-02-17) Mondragón-Martínez, Aarón; Martínez-Rojas, Rosa; Gárate, Inés; Sánchez-Venegas, Jaime R; Moreno-Morales, Gerald; Cruz-Neyra, Lidia; Cruces, Celso Luis; Garcia-Candela, Enrique; Escudero, Frank Guzman; Chero, Jhon D; Yunis-Aguinaga, Jefferson; Štefka, Jan; Nazarizadeh, Masoud
Ligula intestinalis (Cestoda: Diphyllobothriidea) is a cosmopolitan tapeworm parasite characterized by a complex life cycle that includes freshwater fish infection. Ligula disrupts host reproduction, and causes ecological imbalances. Despite its broad geographic distribution and ecological significance, molecular data for South American populations have been lacking, leaving a critical gap in understanding its genetic diversity and evolutionary history. To address this, we conducted the first molecular characterization of L. intestinalis plerocercoid larvae isolated from the native fish Orestias agassizii in Lake Titicaca, Peru. Using Illumina next-generation sequencing, we assembled a complete mitochondrial genome of 13,657 bp, containing 12 protein-coding genes, 22 tRNA genes, two rRNA genes, and two non-coding regions. The mitogenome exhibited an A + T-rich composition (66.3%) and contained over 580 repetitive elements, primarily concentrated within its control region. Comparative analyses with European and Asian mitogenomes revealed substantial regional differences in nucleotide diversity and amino acid composition, with closer similarity observed between South American and Asian lineages. Genes atp6, nad5, and nad6 showed the highest variability, whereas cox1 demonstrated significant intercontinental divergence yet remained conserved within South America, reflecting both phylogeographic patterns and strong functional constraints. Phylogenetic inference based on mitochondrial markers (cytb, cox1, and nd1) confirmed the Titicaca specimen as a distinct South American lineage, closely related to the Nearctic lineage. These findings enhance our understanding of L. intestinalis mitogenomic diversity, emphasize the importance of geographic isolation in parasite diversification, and provide an essential genomic resource for future evolutionary and ecological research in high-altitude ecosystems.
Molecular and morphological identification of Adenocephalus pacificus (Cestoda) isolated from South American sea lion Otaria byronia stranded on the northern Peruvian coasts
(Polish Parasitological Society, 2021) Mondragón-Martiínez, Aarón; Martínez-Rojas, Rosa; Cruz-Neyra, Lidia; De-Los-Santos, Estrellita Rojas; Delgado-Candela, Abraham
The most frequent etiologic agent of diphyllobothriosis in South America and the only one confirmed by molecular data in human cases in Peru is Adenocephalus pacificus (syn. Diphyllobothrium pacificum). This cestode is transmitted by ingestion of the plerocercoids found in marine fish, causing a parasitic zoonosis. The objective of the present study was to identify two cestodes isolated from two specimens of the South American sea lion (Otaria byronia) stranded on the beaches of Huacho and Barranca cities, located on the northern Peruvian coasts, in the department of Lima. Tapeworms were confirmed by morphological characteristics due to the presence of transverse papilla-like tegumental protuberances in proglottids and small sized eggs, as well as by sequencing of the partial cytochrome c oxidase subunit 1 (mtDNA-COI) gene that are congruent with additional available A. pacificus sequences. Even though sea lions in Peru are distributed along the coast and in areas of difficult access, generally located in protected natural areas, the fortuitous finding represented an opportunity to confirm the presence of A. pacificus in South American sea lions. This report of tapeworm A. pacificus could allow future monitoring of the occurrence and geographical distribution of this causative agent in epidemiological studies, since it is one of the main species of zoonotic importance in Peru. © 2024 Elsevier B.V., All rights reserved.
Molecular identification and epidemiological data of Anisakis spp. (Nematoda: Anisakidae) larvae from Southeastern Pacific Ocean off Peru
(Elsevier BV, 2021-12) Martínez-Rojas, Rosa; Mondragón-Martínez, Aarón; De-Los-Santos, Estrellita Rojas; Cruz-Neyra, Lidia; García-Candela, Enrique; Delgado-Escalante, Abraham; Sanchez-Venegas, J.R.
The objective of this study is to determine the infection status of nematode larvae and record epidemiological molecular data in commercial fish from the southeast Pacific off the central coast of Peru. Anisakiasis is a fish-borne zoonosis caused by Anisakis larvae, parasites of relevance in the fishery resources that have negative impact on public health. Between January 2012 to December 2014, 345 specimens of four fish species (Trachurus symmetricus murphyi, Scomber japonicus peruanus, Merluccius gayi peruanus and Seriolella violacea) were examined for Anisakis sp. larvae. A total of 997 Anisakis sp. larvae were found in the body cavity of 196 fish (total prevalence 53.7%, total mean intensity 5.08). After morphological analysis, 958 (96.08%) larvae were identified as Type I and 39 (3.92%) as Type II. Specimens were identified by molecular analysis of the mitochondrial cytochrome c oxidase subunit II (cox2) gene, confirming that A. pegreffii is the predominant species and the most important agent of human anisakiasis off the Peru Central Coast. In addition, we revealed the occurrence of A. physeteris (s.l.) in S. japonicus peruanus (P = 18.0%; MI = 2.17). Therefore, the results obtained in the present study improve the knowledge of the occurrence of Anisakis species in the commercial fish from the Southeastern Pacific Ocean, highlighting the importance of considering a potential hazard for humans and the necessity of further research in other fishes of greater preference by the Peruvian population. © 2021 Elsevier B.V., All rights reserved.