Ultrastructure of the organ of Corti in harbor seals (Phoca vitulina)

Ultrastructural descriptions of the inner ear of highly sound-dependent mammalian species are lacking and needed to gain a better understanding of the hearing sense. Here, we present the first morphometric descriptions of the sensory cells of the inner ear in the harbor seal (Phoca vitulina), a mammal with broadly sensitive amphibious hearing. Scanning electron micrographs of the apical surface of the outer hair cells (OHCs) and inner hair cells (IHCs) within the organ of Corti were obtained from five individuals and analyzed by linear and geometric morphometrics. Measurements were taken at regular locations along the cochlea. The spiral shape of the seal cochlea contained two and a half turns. The organ of Corti had an average length of 27.7 mm with 12,628 OHCs (12,400-12,900). Six linear morphometric parameters showed significant patterns of change associated with their location within the cochlear spiral. Likewise, these trends were similarly expressed in cell configuration (cell blocks with 57 landmarks in 12 representative cells) revealed by geometric morphometry. Cell configuration varied predictably with position in the cochlea according to clustering analyses and Procrustes ANOVA (F= 25.936, p<0001). Changes associated with OHCs were primarily responsible for observed changes in cell configuration. An integration trend in cell shape change was also observed in which IHCs and OHCs share features in their morphological variation by the two-block partial least squares analysis (CR=0.987, p<0.001) and the modularity hypothesis (CV=0.99, p=0.05). These descriptive and quantitative findings provide a baseline for the morphology and morphometry of the sensory cells of the organ of Corti in harbor seals, allowing for comparisons between normal and pathological features. This initial morphological description should enable the correlation between position, morphometric features, and frequency coding along the spiral of the inner ear in this species, whose hearing ability is well studied

Clinicopathological alterations in wild mammals from the reservoir system of Trypanosoma cruzi: a scoping review

Abstract Trypanosoma cruzi is the etiologic agent of Chagas disease. This flagellated protozoan is transmitted to humans as well as different species of domestic and wild animals via vectors from the Reduviidae family (known as “kissing bugs”). Despite the fact that hundreds of species of wild mammals are part of the reservoir system, the morphological changes and clinical manifestations resulting from the pathogenesis of the infection have been largely neglected. The aim of this review is to systematically compile the available information regarding clinicopathological alterations in wild mammals due to natural infection by T. cruzi. Information was obtained from six online bibliographic data search platforms, resulting in the identification of 29 publications that met the inclusion criteria. Mortality was the most common clinical manifestation, cardiac damage was the main finding at necropsy, and lymphoplasmacytic inflammation was the most frequent microscopic injury. Thus, regardless of its role as a reservoir, T. cruzi has the potential to affect the health status of wild mammals, a situation that highlights the need for further research to analyze, measure, and compare its effects at both the individual and population levels

Environmental factors associated With Toxoplasma gondii Exposure in Neotropical Primates of Costa Rica.

The apicomplexan parasite Toxoplasma gondii (T. gondii) has been found in more than 350 species of homoeothermic vertebrates in diverse climates and geographic areas. In most animals, T. gondii produces mild or asymptomatic infection. However, acute and hyperacute toxoplasmosis is associated with high mortality rates observed in Neotropical primates (NP) in captivity. These primates are distributed in 20 countries across the Americas, and although infection has been reported in certain countries and species, toxoplasmosis in the wild and its impact on NP population survival is unknown. Differences among species in exposure rates and disease susceptibility may be due in part to differences in host behavior and ecology. Four species of NP are found in Costa Rica, i.e., howler (Alouatta palliata), spider (Ateles geoffroyi), capuchin (Cebus imitator), and squirrel monkeys (Saimiri oerstedii). This study reports NP exposure to T. gondii using the modified agglutination test in 245 serum samples of NP (198 wild and 47 from captivity) from Costa Rica. Associations of serostatus with environmental (forest cover, annual mean temperature), anthropogenic (human population density), and biological (sex) variables in howler and capuchin monkeys were evaluated. The seroprevalence among wild NP was 11.6% (95% CI = 7.7-17.34), compared with 60% in captive monkeys (95% CI = 44.27-73.63), with significant differences between species (X 2 = 20.072; df = 3, p = 0.000164), suggesting an effect of behavior and ecology. In general, antibody titers were low for wild NP (<1:128) and high for captive NP (>1:8192), suggesting higher exposure due to management factors and increased life span in captivity. Seropositivity in howler monkeys was positively related to forest cover and inversely related to annual rainfall. For capuchins, annual rainfall was inversely related to seropositivity. Surveillance of T. gondii exposure in NP in captivity and in the wild is required to understand drivers of the infection and develop novel strategies to protect them

Composición de comunidades y filoespecificidad de ectoparásitos de murciélagos en paisajes agropecuarios de Veracruz, México.

ABSTRACT: The influence of the anthropogenic transformation of the landscape by livestock activities on the composition and specificity of ectoparasite communities associated with bats was evaluated in livestock productions of the state of Veracruz. Sites with different levels of landscape transformation were compared, including productions under grazing systems in fallow land, silvopasture, and grassland. A total of 944 bats of 23 species were captured in eight livestock production units. The taxonomic identification of 1 433 ectoparasites of 35 species obtained from 428 hosts was carried out. Analyses of taxonomic diversity and phylogenetic specificity were performed between the bat-ectoparasite associations. The composition of the ectoparasite communities associated with Artibeus jamaicensis showed significant differences between the three levels of landscape transformation. The acahual (fallow land), which is the landscape with the least anthropogenic transformation, presented the highest values of diversity of bat species and ectoparasites. The phylospecificity of the streblid bat flies did not show significant changes between the different types of landscape in the study. The consideration of anthropogenic factors that affect the richness, abundance and diversity of the ectoparasites, as well as the phylogenetic relationship with their hosts, is essential to achieve an in-depth study of host-parasite associations.RESUMEN: Se evaluó la influencia de la transformación antropogénica del paisaje por actividades pecuarias sobre la composición y especificidad de las comunidades de ectoparásitos asociadas a murciélagos, en ranchos ganaderos del estado de Veracruz. Se compararon sitios con diferente nivel de transformación del paisaje que incluyeron producciones bajo sistemas de pastoreo en acahual, silvopastoril y pastizal. Se capturaron 944 murciélagos de 23 especies en ocho unidades de producción pecuaria. Se realizó la identificación taxonómica de 1 433 ectoparásitos de 35 especies obtenidos a partir de 428 hospederos. Se realizaron análisis de diversidad taxonómica y especificidad filogenética entre las asociaciones murciélago-ectoparásito. La composición de las comunidades de ectoparásitos asociadas con Artibeus jamaicensis mostró diferencias significativas entre los tres niveles de transformación del paisaje. El acahual, que es el paisaje con menor transformación antropogénica, presentó los valores más altos de diversidad de especies de murciélagos y de ectoparásitos. La filoespecificidad de los estréblidos no presentó cambios significativos entre los diferentes tipos de paisaje del estudio. La consideración de factores antropogénicos que afecten la riqueza, abundancia y diversidad de los ectoparásitos, así como la relación filogenética con sus hospederos es esencial para profundizar en el estudio de las asociaciones hospedero-parásito