Batrachochytrium dendrobatidis Shows High Genetic Diversity and Ecological Niche Specificity among Haplotypes in the Maya Mountains of Belize

The amphibian pathogen Batrachochytrium dendrobatidis (Bd) has been implicated in amphibian declines around the globe. Although it has been found in most countries in Central America, its presence has never been assessed in Belize. We set out to determine the range, prevalence, and diversity of Bd using quantitative PCR (qPCR) and sequencing of a portion of the 5.8 s and ITS1-2 regions. Swabs were collected from 524 amphibians of at least 26 species in the protected areas of the Maya Mountains of Belize. We sequenced a subset of 72 samples that had tested positive for Bd by qPCR at least once; 30 samples were verified as Bd. Eight unique Bd haplotypes were identified in the Maya Mountains, five of which were previously undescribed. We identified unique ecological niches for the two most broadly distributed haplotypes. Combined with data showing differing virulence shown in different strains in other studies, the 5.8 s - ITS1-2 region diversity found in this study suggests that there may be substantial differences among populations or haplotypes. Future work should focus on whether specific haplotypes for other genomic regions and possibly pathogenicity can be associated with haplotypes at this locus, as well as the integration of molecular tools with other ecological tools to elucidate the ecology and pathogenicity of Bd

Anguillicola (Anguillicoides) crassus: Morphometric characteristics and pathogenicity in eels (Anguilla anguilla) in Greece

Anguillicola (Anguillicoides) crassus is a swimbladder nematode parasite of Anguilla anguilla (Linnaeus, 1758). The present study investigates the morphology and pathogenicity of A. crassus in European eel, as well as, the effects of different aquatic environments on the infection of A. crassus, in Greece. A total of 268 nematodes were collected from four estuarine systems in Greece. In all collected parasites, measurements carried out to define the morphological characteristics of parasites: parasite length and width, oesophagus max length and max width. Τhe mean parasite length was 23.50 mm (95% CI: 22.42–24.58) for females, 12.95 mm (95% CI: 12.25–13.64) for the males and 6.39 mm (95% CI: 5.27–7.50) for the juveniles. The mean parasite width was 1.99 mm (95% CI: 1.88–2.10) for females, 0.93 mm (95% CI: 0.86–1.00) for males and 0.51 mm (95% CI: 0.39–0.64) for juveniles. In total, the mean intensity was found 3.15 (95% CI: 2.53–3.78), while the highest mean intensity per eel was 8.00 (95% CI: 0.00–29.51) in Tholi Lagoon and the lowest was 2.20 (95% CI: 0.36–4.04) in Amvrakikos Gulf. Longitudinal and transverse histological sections of two adults A. crassus and two swimbladders were carried out. Multiple granules were observed, as a tissue reaction of the organism to swath around the 4th stage larvae (L4) that have entered the swimbladder. Molecular analysis was performed on three female adults A. crassus derived from eel specimens coming from the Vistonis estuarine system. The high reproductive capacity of the parasite reveals that A. anguilla has low effective defense mechanisms against the parasite. Also, the morphometric variations of the A. crassus seems to have a plastic feature which is being differently expressed when exposed to various environments. © 202