Meeting Abstract
Global warming is a phenomenon that is increasingly difficult to deny and has been linked to the increasing temperature of sea water which is a form of environmental stress for aquatic organisms. To understand the effects of feverish temperature on gonadal functions in economically and environmentally important marine invertebrates, Atlantic sea urchin were collected from South Padre Island in the Gulf of Mexico and placed in six aquariums (capacity: 20-gallon) with high temperatures (28 and 32oC) and control variable (24oC) under controlled laboratory conditions. After one week of exposure to different temperatures, gonadal tissue samples were collected to analyze the effects of warmer temperature on gonadal apoptosis and reproductive functions in sea urchin. Gonadal tissues were sectioned and stained with hematoxylin-eosin, and the proportions of mature egg (ova) and sperm contents were determined. Sea urchin exposed to high temperatures had the lowest gonadosomatic index compared to controls. Ovaries and testes from sea urchin exposed to high temperature showed a decrease in the proportion of ova and sperm contents, respectively. Colorimetric in situ TUNEL assay and caspase activity were also conducted to evaluate cellular apoptosis in gonadal tissues. Ovaries from sea urchin exposed to high temperature showed an increased proportion of TUNEL-positive cells compared to controls. Massive apoptotic cells detected by TUNEL signals were also observed in testicular tissues after exposure to high temperature. Caspase activity was significantly increased in ovary and testis protein of sea urchin exposed to high temperature compared to controls. Collectively, our results suggest that elevated water temperature induces gonadal apoptosis which might be involved in the impairment of reproductive functions in Atlantic sea urchin.
