Conformation-associated health in pet rabbits in the UK: A VetCompass cohort study.

BACKGROUND: Domestic rabbit breeds vary substantially from the wild rabbit body type. However, little is known about how the conformation of pet rabbits influences their health. METHODS: Data were extracted from VetCompass anonymised clinical records of rabbits under UK primary veterinary care during 2019. RESULTS: The study included 162,107 rabbits. Based on 88,693 rabbits with relevant breed information recorded, skull shape was classified as brachycephalic (79.69%), mesaticephalic (16.80%) and dolichocephalic (3.51%). Based on 83,821 rabbits with relevant breed information recorded, ear carriage was classified as lop-eared (57.05%) and erect-eared (42.95%). From a random sample of 3933 rabbits, the most prevalent disorders recorded overall were overgrown nail(s) (28.19%), overgrown molar(s) (14.90%) and obesity (8.82%). Compared to those with a mesaticephalic skull shape, brachycephalic rabbits had lower odds of obesity, anorexia and gastrointestinal stasis and higher odds of perineal faecal impaction, tear duct abnormality and haircoat disorder. Compared to erect-eared rabbits, lop-eared rabbits had higher odds of perineal faecal impaction and tear duct abnormality. LIMITATION: A large proportion of records with incomplete breed information hindered full analysis for breed-related and conformation-related attributes. CONCLUSION: Limited evidence for major links between skull shape or ear carriage conformations and overall disorder risk suggests that factors such as husbandry or even just living life as a domesticated species may be bigger drivers of common health issues in pet rabbits in the UK.

Ames test study designs for nitrosamine mutagenicity testing: qualitative and quantitative analysis of key assay parameters.

The robust control of genotoxic N-nitrosamine (NA) impurities is an important safety consideration for the pharmaceutical industry, especially considering recent drug product withdrawals. NAs belong to the 'cohort of concern' list of genotoxic impurities (ICH M7) because of the mutagenic and carcinogenic potency of this chemical class. In addition, regulatory concerns exist regarding the capacity of the Ames test to predict the carcinogenic potential of NAs because of historically discordant results. The reasons postulated to explain these discordant data generally point to aspects of Ames test study design. These include vehicle solvent choice, liver S9 species, bacterial strain, compound concentration, and use of pre-incubation versus plate incorporation methods. Many of these concerns have their roots in historical data generated prior to the harmonization of Ames test guidelines. Therefore, we investigated various Ames test assay parameters and used qualitative analysis and quantitative benchmark dose modelling to identify which combinations provided the most sensitive conditions in terms of mutagenic potency. Two alkyl-nitrosamines, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were studied. NDMA and NDEA mutagenicity was readily detected in the Ames test and key assay parameters were identified that contributed to assay sensitivity rankings. The pre-incubation method (30-min incubation), appropriate vehicle (water or methanol), and hamster-induced liver S9, alongside Salmonella typhimurium strains TA100 and TA1535 and Escherichia coli strain WP2uvrA(pKM101) provide the most sensitive combination of assay parameters in terms of NDMA and NDEA mutagenic potency in the Ames test. Using these parameters and further quantitative benchmark dose modelling, we show that N-nitrosomethylethylamine (NMEA) is positive in Ames test and therefore should no longer be considered a historically discordant NA. The results presented herein define a sensitive Ames test design that can be deployed for the assessment of NAs to support robust impurity qualifications.

Unigems: plasmids and parts to facilitate teaching on assembly, gene expression control and logic in E. coli.

Synthetic biology enables the creative combination of engineering and molecular biology for exploration of fundamental aspects of biological phenomena. However, there are limited resources available for such applications in the educational context, where straightforward setup, easily measurable phenotypes and extensibility are of particular importance. We developed unigems, a set of ten plasmids that enable classroom-based investigation of gene-expression control and biological logic gates to facilitate teaching synthetic biology and genetic engineering. It is built on a high-copy plasmid backbone and is easily extensible thanks to a common primer set that facilitates Gibson assembly of PCR-generated or synthesized DNA parts into the target vector. It includes two reporter genes with either two constitutive (high- or low-level) or two inducible (lactose- or arabinose-) promoters, as well as a single-plasmid implementation of an AND logic gate. The set can readily be employed in undergraduate teaching settings, during outreach events and for training of iGEM teams. All plasmids have been deposited in Addgene.