Molecular data reshape our understanding of the life cycles of three digeneans (Monorchiidae and Gymnophallidae) infecting the bivalve, Donax variabilis: it’s just a facultative host!

The coquina, Donax variabilis, is a known intermediate host of monorchiid and gymnophallid digeneans. Limited morphological criteria for the host and the digeneans’ larval stages have caused confusion in records. Herein, identities of coquinas from the United States (US) Atlantic coast were verified molecularly. We demonstrate that the current GenBank sequences for D. variabilis are erroneous, with the US sequence referring to D. fossor. Two cercariae and three metacercariae previously described in the Gulf of Mexico and one new cercaria were identified morphologically and molecularly, with only metacercariae occurring in both hosts. On the Southeast Atlantic coast, D. variabilis’ role is limited to being a facultative second intermediate host, and D. fossor, an older species, acts as both first and second intermediate hosts. Sequencing demonstrated 100% similarities between larval stages for each of the three digeneans. Sporocysts, single tail cercariae, and metacercariae in the incurrent siphon had sequences identical to those of monorchiid Lasiotocus trachinoti, for which we provide the complete life cycle. Adults are not known for the other two digeneans, and sequences from their larval stages were not identical to any in GenBank. Large sporocysts, cercariae (Cercaria choanura), and metacercariae in the coquinas’ foot were identified as Lasiotocus choanura (Hopkins, 1958) n. comb. Small sporocysts, furcocercous cercariae, and metacercariae in the mantle were identified as gymnophallid Parvatrema cf. donacis. We clarify records wherein authors recognized the three digenean species but confused their life stages, and probably the hosts, as D. variabilis is sympatric with cryptic D. texasianus in the Gulf of Mexico.

KOMPOSISI ASAM LEMAK KERANG BUAH (Donax variabillis) PREPARASI DENGAN PEMANASAN UNTUK MELEPAS CANGKANG

Kerang “Buah” (Donax variabillis.) merupakan salah satu biota laut yang banyak dikonsumsi terutama karena kandungan proteinnya yang tinggi. Kerang “Buah” biasanya diolah dengan cara kerang dilepas dari cangkang dengan pisau atau dipanaskan, setelah itu direbus dan di tumis dengan bumbu-bumbu seperti bawang putih bawang merah dan caberawit[TR1] . Kerang dimanfaatkan oleh masyarakat sebagai bahan makanan sudah cukup lama namun kandungan gizi terutama perubahan kandungan lemak dan komposisi asam lemak akibat penanganan kerang belum ada penelitian serta informasinya. Penelitian bertujuan untuk membandingkan kandungan lemak dan profil asam lemak kerang “Buah” (Donax variabillis.) perlakuan pelepasan cangjang dengan dipanaskan dan tanpa dipanaskan. Metode penelitian yang digunakan adalah eksperimen dan dilakukan analisa kandungan lemak dan profil asam lemak kerang. Hasil penelitian menunjukkan bahwa kandungan lemak kerang buah ( Donax variabilis ) perlakuan dipanaskan meningkat sedangkan kadar air menuru. Kandungan asam lemak daging kerang buah ( Donax variabilis ) terdeteksi 24 jenis asam lemak yang terdiri dari dari 10 asam lemak jenuh (Saturated Fatty Acid/SAFA), 5 asam lemak tak jenuh tunggal ( Monounsauturated Fatty Acid/MUFA) dan 9 asam lemak jenuh jamak (Polysaturated Fatty Acid/PUFA). Kandungan asam lemak jenuh (SAFA) menurun demikian pula asam lemak omega-3, EPA dan DHA menurun tetapi asam lemak jenuh tunggal (MUFA) meningkat dengan perlakuan dipanaskan.[TR2]