GASTROINTESTINAL TRACT ADENOCARCINOMA IDENTIFIED IN CAPTIVE GILA MONSTERS (HELODERMA SUSPECTUM) IN A NORTH AMERICAN ZOO, 1997-2023.

Neoplasia in the Gila monster (Heloderma suspectum) is not commonly investigated, and literature regarding the prevalence and type of neoplasms that affect this species is sparse. Gastrointestinal tract adenocarcinoma (GTA) in particular has only been reported twice in Gila monsters, once in the small intestine and once in the colon. In this case series, 50% (7/14) of the Gila monsters presented to the pathology service at Smithsonian's National Zoo and Conservation Biology Institute (SNZCBI) over the span of 26 yr (1997-2023) were found to have intestinal and/or colonic adenocarcinoma. The frequency of GTA reported in this collection likely represents a multifactorial etiology including geriatric age of specimens, chronic inflammation, gastrointestinal tract infection, and/or increased cognizance of the disease because of previous reports within the collection. An increased awareness of GTA in this species may lead to improved recognition of the disease.

Lack of Dosage Balance and Incomplete Dosage Compensation in the ZZ/ZW Gila Monster (Heloderma suspectum) Revealed by De Novo Genome Assembly.

Reptiles exhibit a variety of modes of sex determination, including both temperature-dependent and genetic mechanisms. Among those species with genetic sex determination, sex chromosomes of varying heterogamety (XX/XY and ZZ/ZW) have been observed with different degrees of differentiation. Karyotype studies have demonstrated that Gila monsters (Heloderma suspectum) have ZZ/ZW sex determination and this system is likely homologous to the ZZ/ZW system in the Komodo dragon (Varanus komodoensis), but little else is known about their sex chromosomes. Here, we report the assembly and analysis of the Gila monster genome. We generated a de novo draft genome assembly for a male using 10X Genomics technology. We further generated and analyzed short-read whole genome sequencing and whole transcriptome sequencing data for three males and three females. By comparing female and male genomic data, we identified four putative Z chromosome scaffolds. These putative Z chromosome scaffolds are homologous to Z-linked scaffolds identified in the Komodo dragon. Further, by analyzing RNAseq data, we observed evidence of incomplete dosage compensation between the Gila monster Z chromosome and autosomes and a lack of balance in Z-linked expression between the sexes. In particular, we observe lower expression of the Z in females (ZW) than males (ZZ) on a global basis, though we find evidence suggesting local gene-by-gene compensation. This pattern has been observed in most other ZZ/ZW systems studied to date and may represent a general pattern for female heterogamety in vertebrates.

The toxicology of Heloderma suspectum: the Gila monster

The biotoxicology of Heloderma suspectum, the Gila monster, is presented in order to complement the homeopathic provings. (AU)