Illustrations for Health Assessment Techniques of the Atlantic Horseshoe Crab, Limulus polyphemus

Horseshoe crab blood cells detect extremely small amountsof bacteria allowing them to be used in medicine to test thesterilization of medical devices, vaccines, and implants. This is aworldwide standard test called Limulus Amebocyte Lysate. TheNational Aquarium in Baltimore, MD, has developed guidelinesfor health examinations that are aimed to improve healthmaintenance and conservation strategies for horseshoe crabs.Illustrations were created to accompany this specic literatureto ensure the overall eectiveness of the material. A total of 28color illustrations were created to help educate veterinariansand veterinarian technicians, aquarists, and biologists.

The Draft Genome and Transcriptome of the Atlantic Horseshoe Crab,Limulus polyphemus

The horseshoe crab,Limulus polyphemus, exhibits robust circadian and circatidal rhythms, but little is known about the molecular mechanisms underlying those rhythms. In this study, horseshoe crabs were collected during the day and night as well as high and low tides, and their muscle and central nervous system tissues were processed for genome and transcriptome sequencing, respectively. The genome assembly resulted in7.4×105contigs with N50 of 4,736, while the transcriptome assembly resulted in9.3×104contigs and N50 of 3,497. Analysis of functional completeness by the identification of putative universal orthologs suggests that the transcriptome has three times more total expected orthologs than the genome. Interestingly, RNA-Seq analysis indicated no statistically significant changes in expression level for any circadian core or accessory gene, but there was significant cycling of several noncircadian transcripts. Overall, these assemblies provide a resource to investigate theLimulusclock systems and provide a large dataset for further exploration into the taxonomy and biology of the Atlantic horseshoe crab.