Efficiency of Peptide Nucleic Acid-Directed PCR Clamping and Its Application in the Investigation of Natural Diets of the Japanese Eel Leptocephali

Polymerase chain reaction (PCR)-clamping using blocking primer and DNA-analogs, such as peptide nucleotide acid (PNA), may be used to selectively amplify target DNA for molecular diet analysis. We investigated PCR-clamping efficiency by studying PNA position and mismatch with complementary DNA by designing PNAs at five different positions on the nuclear rDNA internal transcribed spacer 1 of the Japanese eel Anguilla japonica in association with intra-specific nucleotide substitutions. All five PNAs were observed to efficiently inhibit amplification of a fully complementary DNA template. One mismatch between PNA and template DNA inhibited amplification of the template DNA, while two or more mismatches did not. DNA samples extracted from dorsal muscle and intestine of eight wild-caught leptochephalus larvae were subjected to this analysis, followed by cloning, nucleotide sequence analysis, and database homology search. Among 12 sequence types obtained from the intestine sample, six were identified as fungi. No sequence similarities were found in the database for the remaining six types, which were not related to one another. These results, in conjunction with our laboratory observations on larval feeding, suggest that eel leptocephali may not be dependent upon living plankton for their food source

北西および中部太平洋におけるアナゴ科魚類の葉形幼生に関する研究-Ⅰ : 外腸をもつAriosoma-type幼生

黒潮海域からニューカレドニア周辺海域に至る西部太平洋域(36゜N～26゜S、115～177゜E)に出現するアナゴ科のAriosoma-type幼生は、外腸の有無によって2つのグループに分けられる。本研究では外腸をもつ幼生について、形態と地理的分布を明らかにした。これらの幼生は体側の筋隔上に体軸に沿って並ぶ小黒色素胞列の数(1～3列)によって次の3グループに分けられた。1)体側の小黒色素胞列は1列(TypeA₁～A₅)。このグループは背縁部の小黒色素胞の有無によってさらに2グループに分けられる。背縁部に小黒色素胞をもたない幼生(Type A₁)は体側の筋節上に散在する小黒色素胞を有する。背縁部に小黒色素胞をもつグループは総筋節数と戯終垂直血管の位置によって4タイプ(TypeA₂～A₅)に類別される。2)体側の小黒色素胞列は2列(TypeB₁、B₂)。このグループは鰓蓋の内側と体側正中線直上部の小黒色素胞の有無によって2タイプに類別される。3)体側の小黒色素胞列は3列(TypeC₁、C₂)。このグループは体側の正中線付近の黒色素叢の有無によって2タイプに類別される。 これら9タイプはそれぞれ種に相当し、ゴテンアナゴ亜科(Bathymyrinae)に属すると考えられる。これらのうち、Type A₂、A₄、A₅、B₁、B₂は本研究によって初めて記載され、TypeA₁.A₂、A₄は北西太平洋から初記録である。また、名タイプの筋節数構成より、腹椎と尾椎の数が知られているゴテンアナゴ亜科の親魚との関連について論じた。各タイプの地理的分布図を示し、小型の幼生が採集されたタイプについては、産卵場の推定を行った。これらの幼生は主として、夜間の表層と中層(ワイヤー長、75～200m)で採集され、昼間の各層の曳網でははとんど採集されなかった。Ariosoma-type larvae with outer-intestine (exterilium) of the eel family Congridae from the western North and Middle Pacific are described and characterized. Nine types are recorded based on pigmentation, position of last vertical blood vessel at myomere level and number of myomeres. Five types from the western North Pacific and their relationship with the adult are discussed. None has been conclusively identified with the adult. A key is provided to the exterilium Ariosoma-type larvae known from the western North and Middle Pacific. Distribution maps showing capture locations are given for each type

Fig. 2 in First Japanese Records of Bathycongrus castlei (Teleostei: Anguilliformes: Congridae) from Tosa Bay, Kochi Prefecture

Fig. 2. Schematic illustration of the head of Bathycongrus castlei, NSMT-P 132343, 352+mm TL. Abbreviations: SO, supraorbital pores; IO, infraorbital pores; POM, preoperculomandibular pores; ST, supratemporal pore.Published as part of Sakai, Kyohei, Ohkawa, Toshiyuki & Mochioka, Noritaka, 2022, First Japanese Records of Bathycongrus castlei (Teleostei: Anguilliformes: Congridae) from Tosa Bay, Kochi Prefecture, pp. 341-346 in Species Diversity 27 (2) on page 344, DOI: 10.12782/specdiv.27.341, http://zenodo.org/record/752276

Species composition, abundance and seasonal inshore recruitment patterns of the tropical eels Anguilla spp. to Viti Levu, Fiji Islands in the western South Pacific

To understand the inshore recruitment mechanisms of tropical eels, Anguilla spp., we collected 1368 glass eels at the mouth of a small river at Namelimeli, approximately 2km East of Navua Town, Fiji Islands between April 2015 and June 2016. Specimens were identified using both morphological characters and DNA barcoding to only 3 species; one short-finned Anguilla obscura and two long-finned eels A. marmorata and A. megastoma. A. obscura was the most abundant species (55% of collected glass eels) with peak recruitment periods from February to April. A. marmorata was the second most abundant species (41.4% of collected glass eels) with peak recruitment periods in April 2015 and September to October 2015. A. megastoma only comprised of 3.9% of collected glass eels with peak recruitment periods in April 2015 and October 2015. A. obscura and A. marmorata were present in samples almost throughout the year suggesting that tropical eels recruit to some degree throughout the year. Results suggest that peak recruitment occurs during seasons of heavy rain, from September to October and February to April commencing one hour after sunset on the day following new moo