Search

The complete mitogenome can provide valuable genetic information to reconstruct relationships between species. In this study, we sequenced a stone loach, Homatula laxiclathra (Teleostei: Nemacheilidae), which is found in the northern region of the Qinling Mountains in China. The size of the H. laxiclathra mitogenome is 16,570 bp, which contains 37 typical mitochondrial genes including 13 protein‐coding genes, 22 transfer RNAs, two ribosomal RNAs, and a control region (D‐loop) with a total AT content of 55.8%. This is similar to other Nemacheilidae sequences published in GenBank. Furthermore, a mito‐phylogenomic analysis of 46 Nemacheilidae species places H. laxiclathra in a robust monophyletic Homatula cluster with other Homatula species. Our results contribute toward a better understanding of a true phylogeny of these species based on large‐scale taxonomic samplings as well as to help grasp the evolution of fish mitogenomes. [ABSTRACT FROM AUTHOR]

Although predator exposure increases the risk of wound infections, it typically induces immunosuppression. A number of non-mutually exclusive hypotheses have been put forward to explain this immunosuppression, including: trade-offs between the immune system and other systems required for anti-predator behaviour, redistribution of immune resources towards mechanisms needed to defend against wound infections, and reconfiguration of the immune system to optimize defence under the physiological state of fight-or-flight readiness. We tested the ability of each hypothesis to explain the effects of chronic predator stress on the immune system of the caterpillar Manduca sexta. Predator exposure induced defensive behaviours, reduced mass gain, increased development time and increased the concentration of the stress neurohormone octopamine. It had no significant effect on haemocyte number, melanization rate, phenoloxidase activity, lysozyme-like activity or nodule production. Predator stress reduced haemolymph glutathione concentrations. It also increased constitutive expression of the antimicrobial peptide attacin-1 but reduced attacin-1 expression in response to an immune challenge. These results best fit the immune reconfiguration hypothesis, although the other hypotheses are also consistent with some results. Interpreting stress-related changes in immune function may require an examination at the level of the whole organism. [ABSTRACT FROM AUTHOR]

A new host record for Pseudocapillaria (Pseudocapillaria) tomentosa (Dujardin, 1843) Moravec, 1987 from the intestine of red shiner, Cyprinella lutrensis, imported from a commercial facility in Missouri to a research facility in Wisconsin is described. Prevalence of infection was 85%. Intensity of infection was 1-26 worms per host. Supplementary information involving sequence data (18S ribosomal RNA gene) and new details of the male spicule are provided. The issue of parasite dispersal through the baitfish trade is briefly discussed. [ABSTRACT FROM AUTHOR]

Myxobolus bilobus n. sp. (Myxozoa) is described from golden shiner Notemigonus crysoleucas in Algonquin Park, Ontario, Canada. Plasmodia develop at the distal end of gill filaments, where they form a novel-shaped plasmodium made up of 2 side-by-side hemispheres joined at a central pore. Surrounding gill tissue is vacuolated, necrotic, and hemorrhagic. Spores of M. bilobus n. sp. resemble those of M. aureatus Ward, 1919, M. angustus Kudo, 1934, M. spalli Landsberg & Lom, 1991, and M. pseudokoi Li & Desser, 1985 in parasitizing cyprinids and in their pyriform shape. Spores of M. bilobus n. sp., however, are much larger (20 to 22.1 microm long, 7.5 to 9.3 microm wide, and 6 microm thick) than those of these other species, and the plasmodium is bi-lobed rather than the typical hollow sphere. A phylogenetic analysis of the 18S rDNA (2014 bp) reveals that M. bilobus n. sp. is a member of a clade that includes 11 species of Myxobolus, all of which are parasites of cyprinid fishes in North America or Eurasia. The study concludes that M. bilobus n. sp. is a member of a clade that has undergone radiation within cyprinid fishes of the 2 continents and that this evolution has involved both host and site switching.