The Two Sides of the Mediterranean: Population Genomics of the Black Sea Urchin Arbacia lixula (Linnaeus, 1758) in a Warming Sea

Global environmental changes may have a profound impact on ecosystems. In this context, it is crucial to gather biological and ecological information of the main species in marine communities to predict and mitigate potential effects of shifts in their distribution, abundance, and interactions. Using genotyping by sequencing (GBS), we assessed the genetic structure of a keystone species in the Mediterranean shallow littoral ecosystems, the black sea urchin Arbacia lixula. This bioengineer species can shape their communities due to its grazing activity and it is experiencing an ongoing expansion with increasing temperatures. The population genomic analyses on 5,241 loci sequenced in 240 individuals from 11 Mediterranean sampled populations revealed that all populations were diverse and showed significant departure from equilibrium. Albeit genetic differentiation was in general shallow, a significant break separated the western and eastern Mediterranean populations, a break not detected in previous studies with less resolutive markers. Notably, no clear effect of the Almería-Oran front, an important break in the Atlanto-Mediterranean transition, could be detected among the western basin populations, where only a slight differentiation of the two northernmost populations was found. Despite the generally low levels of genetic differentiation found, we identified candidate regions for local adaptation by combining different genomic analysis with environmental data. Salinity, rather than temperature, seemed to be an important driver of genetic structure in A. lixula. Overall, from a population genomics standpoint, there is ample scope for A. lixula to continue thriving and adapting in the warming Mediterranean.

Chemical characterization of red cells from the black sea urchin Arbacia lixula by X-ray photoelectron spectroscopy

Red spherula cells from sea urchin coelomic fluid have attracted great interest for their specific and intriguing properties, such as antimicrobial activities and immune response, that probably tie in with their red characteristic pigments.

STUDY OF NUTRITIONAL CONTENTS OF SEA URCHIN GONAD FROM DRINI BEACH, GUNUNG KIDUL, YOGYAKARTA

ABSTRACTThis paper aims to determine the types and contents of protein, fatty acids, amino acids and protein in the gonads of Arbacia lixula, Colobocentrotus atratus, Heterocentrotus trigonarius and Echinotrix diadema from the waters of Drini, Gunung Kidul, Yogyakarta. Kjedal method was used to analyze the protein content, while GC and HPLC methods were employed to analyze amino acids in this study. The results showed that the protein contents of each sample, consequently from highest to lowest, were Heterocentrotus trigonarius (13.3 %), Echinotrix diadema (10.86), Colobocentrotus atratus (10.41) and Arbacia lixula (9.90%). Amino acids analysis from all identified both saturated fatty acids, consisting of lauric acid, myristic acid, palmitic acid, stearic acid, arachidonic acid, lignoceric acid, as well as non-saturated fatty acids, consisting of palmitoleic acid, oleic acid, linoleic acid, erucic acid, EPA, and DHA. The highest contents of non-saturated fatty acids were identified in Colobocentrotus atratus (434.14 mg/100g) and the lowest content in Arbacia lixula (197.71 mg/100g). The highest percentage of essential fatty acids was found in Heterocentrotus trigonarius (0.29%), whereas the lowest was found in Echinotrix diadema (0.19 %). It is concluded that the gonad of Heterocentrotus trigonarius showed the highest protein and essential fatty acids contents. This study also found that Colobocentrotus atratus sea urchin gonads possess the highest content of non-saturated fatty acids (434.14 mg/100g). Keywords: amino acid, fatty acid, protein, sea urchin gonad.