PS 49-152 - CANCELLED - Physicochemical characterization of the exoskeleton of Horseshoe Crab Limulus polyphemus (Chelicerata: Xiphosura) from the Yucatan peninsula, Mexico

Background/Question/Methods

The American horseshoe crab (Limulus polyphemus), has an ecological, evolutive and biomedical important role. This species inhabits the east coast of the United States, from Florida to Maine, and on the Yucatan peninsula, in Mexico. Although, information about ecological and toxicological aspects has recently been enhanced, physicochemical characterization of the exoskeleton of this species is a factor scarcely studied in Mexico. Because of this, a study to determine differences between the two main parts of the body of the L. polyphemus, the prosoma (PR) and the opisthosoma (OP), was carried out. Exoskeleton was collected in Rio Lagartos Biosphere Reserve in Yucatan, Mexico. The samples, as a powder fragments of each of these anatomical parts, with sizes around 2 mm was evaluated for elemental organic chemical analysis (CHONS), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TGA).

Results/Conclusions

The CHONS analysis showed no differences between the chemical structure of PR and OP. Carbon is the chemical element present in the highest proportion, followed by oxygen and nitrogen, with percentages of 45.5%, 26.5% and 13.7% respectively. On the other hand, the FTIR spectra of the PR and OP, both spectra present a wide band between 3600-3000 cm-1, which seems to have several contributions to 3385, 3258 and 3094 cm-1; these bands are due to stretching of the O-H and N-H bonds of the chitin structure. The TGA and DTGA curves of the prosoma and opisthosoma samples showed a similar decomposition profile, exhibiting two mass losses. One of these is associated with the thermal decomposition of the poly (N-acetyl glucosamine) chain and is located at 345°C, according to the first derivative curve. The residual mass at 650°C was slightly higher for the opisthosoma (40%) than for the prosoma (30%), which could indicate that there is a higher mineral content in the back of the exoskeleton, compared to the anterior part of prosoma. These results can expand the genetic data to support the implementation of management and conservation strategies for the species in Mexico.