Columbia spotted frogs (Rana luteiventris) have characteristic skin microbiota that may be shaped by cutaneous skin peptides and the environment.

Global amphibian declines due to the fungal pathogen Batrachochytrium dendrobatidis (Bd) have led to questions about how amphibians defend themselves against skin diseases. A total of two amphibian defense mechanisms are antimicrobial peptides (AMPs), a component of amphibian innate immune defense and symbiotic skin bacteria, which can act in synergy. We characterized components of these factors in four populations of Columbia spotted frogs (Rana luteiventris) to investigate their role in disease defense. We surveyed the ability of their AMPs to inhibit Bd, skin bacterial community composition, skin metabolite profiles and presence and intensity of Bd infection. We found that AMPs from R. luteiventris inhibited Bd in bioassays, but inhibition did not correlate with Bd intensity on frogs. R. luteiventris had two prevalent and abundant core bacteria: Rhizobacter and Chryseobacterium. Rhizobacter relative abundance was negatively correlated with AMP's ability to inhibit Bd, but was not associated with Bd status itself. There was no relationship between metabolites and Bd. Bacterial communities and Bd differ by location, which suggests a strong environmental influence. R. luteiventris are dominated by consistent core bacteria, but also house transient bacteria that are site specific. Our emergent hypothesis is that host control and environmental factors shape the microbiota on R. luteiventris.

Intestinal physiology and regulatory T cell response to immediate or delayed access to feed and water in Pekin ducklings.

This study investigated the effects of delayed access to feed and water on early duckling growth, selected aspects of intestinal physiology, and immune responses. Ducklings were assigned to one of 2 experimental groups. In one treatment group (referred to as the fed group), feed and water were provided beginning on d 0, and in the other treatment group (referred to as the withheld group), feed and water were withheld until d 2. The ducklings in the withheld treatment had lower BW at 2 and 6 d posthatch than ducklings in the fed group. At 8 d posthatch (6 d postfeeding), the BW of the ducklings in the withheld group was comparable to the BW of the 6-d-old ducklings in the fed group. At 2 d posthatch, withheld ducklings had lower absolute and relative duodenum plus pancreas weight than fed ducklings. At 8 d posthatch (6 d postfeeding), withheld ducklings had higher absolute and relative duodenum plus pancreas weight than fed ducklings at 6 d posthatch. At 2 d posthatch, mucin 5B mRNA content was approximately 2 times lower in withheld ducklings (P = 0.09) than in fed ducklings. At 6 d posthatch, mucin 5b mRNA content was approximately 2.5-fold higher in withheld ducklings (P = 0.07) than in fed ducklings. Delayed access to feed and water increased the CD25(+) cell number in the cecal tonsil at 2, 6, and 8 d posthatch. The IL-10 content of CD25(+) cells was higher in the withheld ducklings than in the fed ducklings at 2 and 6 d posthatch. In conclusion, delaying access of ducklings with no experimental pathogen infection to feed and water has no long-term effects on early growth parameters, intestinal physiology, and immune responses.