The American lobster, Homarus americanus, is integral to marine ecosystems and supports an important commercial fishery. This iconic species also serves as a valuable model for deciphering neural networks controlling rhythmic motor patterns and olfaction. Here, we report a high-quality draft assembly of the H. americanus genome with 25,284 predicted gene models. Analysis of the neural gene complement revealed extraordinary development of the chemosensory machinery, including a profound diversification of ligand-gated ion channels and secretory molecules. The discovery of a novel class of chimeric receptors coupling pattern recognition and neurotransmitter binding suggests a deep integration between the neural and immune systems. A robust repertoire of genes involved in innate immunity, genome stability, cell survival, chemical defense, and cuticle formation represents a diversity of defense mechanisms essential to thrive in the benthic marine environment. Together, these unique evolutionary adaptations contribute to the longevity and ecological success of this long-lived benthic predator.

The green crab Carcinus maenas is an invader on the Atlantic coast of Canada and the USA. In these locations, crab populations have facilitated the development of a legal fishery in which C. maenas is caught and sold, mainly for use as bait to capture economically important crustaceans such as American lobster Homarus americanus. The paucity of knowledge on the symbionts of invasive C. maenas in Canada and their potential for transfer to lobsters poses a potential risk of unintended transmission. We carried out a histological survey for symbionts of C. maenas from their native range in Northern Europe (in the UK and Faroe Islands), and invasive range in Atlantic Canada. In total, 19 separate symbiotic associations were identified from C. maenas collected from 27 sites. These included metazoan parasites (nematodes, Profilicollis botulus, Sacculina carcini, Microphallidae, ectoparasitic crustaceans), microbial eukaryotes (ciliates, Hematodinium sp., Haplosporidium littoralis, Ameson pulvis, Parahepatospora carcini, gregarines, amoebae), bacteria (Rickettsia-like organism, milky disease), and viral pathogens (parvo-like virus, herpes-like virus, iridovirus, Carcinus maenas bacilliform virus and a haemocyte-infecting rod-shaped virus). Hematodinium sp. were not observed in the Canadian population; however, parasites such as Trematoda and Acanthocephala were present in all countries despite their complex, multi-species lifecycles. Some pathogens may pose a risk of transmission to other decapods and native fauna via the use of this host in the bait industry, such as the discovery of a virus resembling the previously described white spot syndrome virus (WSSV), B-virus and 'rod-shaped virus' (RV-CM) and amoebae, which have previously been found to cause disease in aquaculture (e.g. Salmo salar) and fisheries species (e.g. H. americanus).

This study evaluated the effect of the delivery of a commercial essential oil blend containing the phytonutrients star anise, cinnamon, rosemary, and thyme oil (via different routes) on broiler chickens’ ileal and ceca microbiota and liver transcriptome compared to an antibiotic growth promoter. Eggs were incubated and allocated into three groups: non-injected, in ovo saline, and in ovo essential oil. On day 18 of incubation, 0.2 mL of essential oil in saline (dilution ratio of 2:1) or saline alone was injected into the amnion. At hatch, chicks were assigned to post-hatch treatment combinations: (A) a negative control (corn-wheat-soybean diet), (B) in-feed antibiotics, (C) in-water essential oil (250 mL/1000 L of drinking water), (D) in ovo saline, (E) in ovo essential oil, and (F) in ovo essential oil plus in-water essential oil in eight replicate cages (six birds/cage) and raised for 28 days. On days 21 and 28, one and two birds per cage were slaughtered, respectively, to collect gut content and liver tissues for further analysis. Alpha and beta diversity differed significantly between ileal and ceca samples but not between treatment groups. In-feed antibiotic treatment significantly increased the proportion of specific bacteria in the family Lachnospiraceae while reducing the proportion of bacteria in the genus Christensenellaceae in the ceca, compared to other treatments. Sex-controlled differential expression of genes related to cell signaling and tight junctions were recorded. This study provides data that could guide the use of these feed additives and a foundation for further research.