First Observations of Buzzards (Buteo) as Definitive Hosts of Sarcocystis Parasites Forming Cysts in the Brain Tissues of Rodents in Lithuania.

Representatives of the genus Sarcocystis are worldwide distributed apicomplexan parasites characterised by two-host prey-predator relationships. Sarcocystis spp. produce sarcocysts in the muscles and brains of intermediate hosts and develop sporocysts in the intestines of definitive hosts. Two species, Sarcocystis glareoli and Sarcocystis microti, previously assigned to the genus Frenkelia, form cysts in the brains of rodents and are transmitted through the common buzzard (Buteo buteo). In our study, brain samples of 694 small mammals caught in different regions of Lithuania were examined for Sarcocystis spp. Additionally, 10 B. buteo and two rough-legged buzzards (Buteo lagopus) were tested for sporocysts of the analysed parasites. Sarcocystis species were identified based on 28S rRNA sequence comparison. Of the eleven species of small mammals tested, Sarcocystis parasites were observed only in the bank vole (Clethrionomys glareolus). Cysts of S. glareoli were detected in 34 out of 374 C. glareolus (9.1%, 95% CI = 6.4-12.5%). Molecular investigation showed the presence of only S. glareoli in the intestines of 50% of B. buteo. Furthermore, two species, Sarcocystis sp. Rod3 and Sarcocystis sp. Rod4, were confirmed in B. lagopus. Our results demonstrate the need for further studies on Sarcocystis cycling between rodents and birds.

Morphological and Molecular Description of Sarcocystis myodes n. sp. from the Bank Vole (Clethrionomys glareolus) in Lithuania

Numerous rodent species have been broadly examined for Sarcocystis parasites. Nevertheless, recent investigations on Sarcocystis spp. in voles are lacking. As many as 45 bank voles (Clethrionomys glareolus) captured in several locations in Lithuania were examined in the present study. Based on morphological, genetic, and phylogenetic results, sarcocysts detected in one bank vole were described as Sarcocystis myodes n. sp. Using light microscopy analysis, the observed sarcocysts were ribbon-shaped, 6000−3000 × 70−220 µm in size. Sarcocysts were characterized by a relatively thin (about 1 µm) and apparently smooth cyst wall. The lancet-shaped bradyzoites were 9.6−12.0 × 3.1−4.6 µm in size. By transmission electron microscopy, the sarcocyst wall was up to 1 µm thick, parasitophorous vacuolar membrane had small knob-like blebs. Based on 18S rDNA, 28S rDNA, cox1, rpoB, and ITS1 loci, S. myodes showed highest similarity with S. ratti from the black rat (Rattus rattus). According to phylogenetic placement, S. myodes was most closely related to Sarcocystis spp. that employ predatory mammals as their definitive hosts. Morphologically, sarcocysts of S. myodes have similar features to those of S. cernae, S. dirumpens, and S. montanaensis described in voles, however, they use birds of prey or snakes as their definitive hosts.

Resource partitioning confirmed by isotopic signatures allows small mammals to share seasonally flooded meadows.

Meadows in river deltas are characterized by a high diversity and abundance of small mammals. However, neither their spatial arrangement nor differences in their use of microhabitat can necessarily explain the dense co-occurrence of sympatric species. We investigated how several small mammal species share a seasonally flooded meadow of limited size, testing predictions (P1) that herbivore, granivore, insectivore, and omnivore species are separated in time (dominant in different years), (P2) that sympatric species undergo isotopic partitioning, and (P3) that there are intraspecific differences in diet. Stable carbon and nitrogen isotope signatures in the hair of seven synantropic shrew, vole, and mice species were used as a proxy for their diet. We found that the three most abundant species in eight of the nine years were from different diet groups. However, based on the number of species in the functional groups, the state of small mammal community was considered unfavored in five out of the nine investigation years. In years with the greatest dominance of Apodemus agrarius, the small mammal community was characterized by decreased diversity and Micromys minutus was either in low abundance or absent. In 2014 and 2016, years of low abundance or absence of M. oeconomus, M. agrestis, and M. glareolus were both recorded in high numbers. Differences in the isotopic signatures of the three most abundant small mammal species in the community were clearly expressed and core areas in the isotopic space were separated, showing their dependence on different dietary resources. Intraspecific dietary separation between young and adult animals was observed only in M. oeconomus. Thus, the high species diversity of small mammals and the formation of their community in this investigated flooded meadow are maintained by isotopic partitioning (segregation in dietary space) and by changes in their number over time (shifting dominance).

Accumulation of chemical elements in yellow-necked mice under a colony of great cormorants.

This study represents the first investigation into the accumulation of chemical elements in small mammals inhabiting the territory of a great cormorant colony. Trapping was done in the Juodkrante great cormorant colony, one of the largest colonies in Europe. The accumulation of 20 chemical elements in the bodies (muscle and bones) of yellow-necked mice (Apodemus flavicollis) was investigated using the energy-dispersive x-ray fluorescence equipment Spectro Xepos HE. Two groups of positively inter-correlated chemical elements (Mg, Al, P, Ca and Al, S, Cl, K) were identified. The concentrations of five elements differed significantly between mice trapped in different zones of the colony with differing intensities of cormorant influence: the values of K and Cu in A. flavicollis increased in line with an increase in the influence of the cormorants, while the concentrations of Rb and Pb decreased. The concentrations of Mn differed between zones, but were not related to the intensity of bird influence. Differences in the concentration of Zn (ANOVA F = 24.38; p < 0.001), Fe (F = 4.60; p < 0.05) and Mo (F = 4.47; p < 0.05) were related to the gender factor, all concentrations being higher in females. The concentrations of Zn were age-dependent, being highest in adult individuals (21.7 ±â€¯4.5 µg g-1) and exceeding those in subadult (19.4 ±â€¯3.4 µg g-1) individuals or juveniles (16.7 ±â€¯1.3 µg g-1). In general, the concentrations of accumulated elements in A. flavicollis from the territory of the cormorant colony were lower than in rodents from industrially polluted sites.

Detection of rat hepatitis E virus, but not human pathogenic hepatitis E virus genotype 1-4 infections in wild rats from Lithuania.

Rat hepatitis E virus (HEV) is an orthohepevirus which is related to other HEV found in humans and other mammals. It was first identified in Norway rats (Rattus norvegicus) from Germany in 2010, and later it has been detected in Black rats (Rattus rattus) and Norway rats from USA, China, Indonesia, Vietnam and many European countries. In this study, we describe molecular and serological investigations of Black and Norway rats trapped in Lithuania, Eastern Europe, for infections with rat HEV and human HEV genotypes 1-4. Rat HEV-specific real-time reverse transcription-PCR (RT-qPCR) analysis of rat liver samples revealed the presence of rat HEV in 9 of 109 (8.3%) samples. In contrast, a RT-qPCR specific for HEV genotypes 1-4 did not reveal any positive samples. A nested broad spectrum RT-PCR was used for a confirmation of rat HEV infection with a subsequent sequencing of the amplified rat HEV genome fragment. Phylogenetic analysis revealed a clustering of all newly identified rat HEV sequences with Norway rat-derived rat HEV sequences from Germany within the species Orthohepevirus C. An indirect ELISA using a yeast-expressed truncated rat HEV capsid protein variant revealed 31.2% seropositive samples indicating a high rate of rat HEV circulation in the rat population examined. In conclusion, the current investigation confirms rat HEV infections in Norway and Black rats in Lithuania, Eastern Europe, and the non-persistent nature of HEV infection.

The impact of Great Cormorants on biogenic pollution of land ecosystems: Stable isotope signatures in small mammals.

Studying the isotopic composition of the hair of two rodent species trapped in the territories of Great Cormorant colonies, we aimed to show that Great Cormorants transfer biogens from aquatic ecosystems to terrestrial ecosystems, and that these substances reach small mammals through the trophic cascade, thus influencing the nutrient balance in the terrestrial ecosystem. Analysis of δ(13)C and δ(15)N was performed on two dominant species of small mammals, Apodemus flavicollis and Myodes glareolus, inhabiting the territories of the colonies. For both species, the values of δ(13)C and δ(15)N were higher in the animals trapped in the territories of the colonies than those in control territories. In the hair of A. flavicollis and M. glareolus, the highest values of δ(15)N (16.31±3.01‰ and 17.86±2.76‰, respectively) were determined in those animals trapped in the biggest Great Cormorant colony. δ(15)N values were age dependent, highest in adult A. flavicollis and M. glareolus and lowest in juvenile animals. For δ(13)C values, age-dependent differences were not registered. δ(15)N values in both small mammal species from the biggest Great Cormorant colony show direct dependence on the intensity of influence. Biogenic pollution is at its strongest in the territories of the colonies with nests, significantly diminishing in the ecotones of the colonies and further in the control zones, where the influence of birds is negligible. Thus, Great Cormorant colonies alter ecosystem functioning by enrichment with biogens, with stable isotope values in small mammals significantly higher in the affected territories.