Paracyclopina Nana Research Articles

Effect of strain and selection line on the fecundity of the cyclopoid copepodParacyclopina nanaSmirnov, 1935

AbstractWe studied the effect of strain and selection lineson the fecundity of the cyclopoid copepod Paracyc-lopina nana. We used six strains (HL, YL, BS, SL,TH, TS) and six isofemale lines (including threehigher and three lower fecundity lines). As for theselection of strain, total nauplii production perfemale of SL strain was the highest in the individ-ual culture (231 nauplii per female) and popula-tion growth rate in HL and SL strains showedhigher values than the others in combined culture.For the selection of line, the total nauplii produc-tion per female of HF 2 -2 (high fecundity and sec-ond generation) line was the highest (302 naupliiper female) but those of LF 2 -1 (low fecundity) (80nauplii per female), and LF 2 -3 (46 nauplii perfemale) lines were lower than the others. In F 4 generation, three selected HF 2 -2 line showed thatthe total nauplii production were higher thanthose of three selected LF 2 -3 lines. In the combinedculture on the different selection lines (F 8 ), popula-tion growth rate of two selected high fecunditylines showed higher values than that of the non-selection group and selected low fecundity line.Our results demonstrate that the production ofP. nana can be improved by selection of the linewith high fecundity.Keywords: live feed, copepod, strain, selection,fecundity, Paracyclopina nanaIntroductionSince mariculture is an ever expanding sector ofthe food-producing industry, the improvement ofnovel technologies for the intensification of cul-tures and farming of seaweed and animals arewarranted (Dahms, Gao & Hwang 2007; Camus Z Drillet,Frouel, Sichlau, Jepsen, Hojgaard, Joarder & Hansen2011). Especially the nauplius larvae of copepodsprovide natural prey items for marine invertebrate

Extensive analysis of nuclear cistron rDNA sequence of Paracyclopina nana (Cyclopoida: Cyclopettidae)

As a special reference of the nuclear cistron rDNA of cyclopoid copepods, we obtained the entire DNA sequence of a single rDNA repeat unit from Paracyclopina nana (Cyclopoida: Cyclopettidae). The genomic organization of P. nana rDNA (7,974 bp, 51.7% of GC) was observed to be 18S–ITS1–5.8S–ITS2–28S–IGS in order. Comparative analyses of the rDNA between P. nana and other copepods showed that the intergenic spacer (IGS) was highly informative and divergent, while other coding regions are relatively conserved. We detected eleven poly(T) tracts in the IGS, demonstrating the high AT content in this region. In addition, many sub-repeat sequence patterns (e.g., AG, AT, GC, CCG, TC) such as microsatellites were identified from the rDNA IGS of P. nana. In this article, we show the first complete sequence of rDNA from the order Cyclopoida, providing a better understanding of molecular characteristics in molecular taxonomy.

Molecular characterization and expression of vitellogenin ( Vg) genes from the cyclopoid copepod, Paracyclopina nana exposed to heavy metals

Induction of vitellogenin ( Vg) has been used as a biomarker of exposure to heavy metals and endocrine-disruption chemicals (EDCs) in aquatic organisms. Here, we identified the full-length Vg1 and Vg2 sequence from the brackish water copepod, Paracyclopina nana. Vg1 gene contained 5718 bp of the open reading frame (ORF) that encoded the putative protein of 1905 amino acids residues, while Vg2 gene consisted of 5442 bp of ORF, encoding the putative protein of 1813 amino acids residues. P. nana Vgs showed highly conserved domains in the N-terminal region. The phylogenetic analysis revealed that P. nana Vgs are distinct from other arthropods, such as insects and decapods, as it formed a clade with other copepods, Tigriopus japonicus and salmon louse ( Lepeophtheirus salmonis). The expression of Vg transcripts was detectable after the copepodid stages 4–5. Female copepods expressed over 83 times and 223 times more Vg1 and Vg2 transcripts, respectively, than males. When copepods were exposed to heavy metals (0.1 mg/L Cd, 0.4 mg/L Cu, and 2 mg/L AsIII) for 24, 48, 72, and 96 h, P. nana Vg transcripts were highly induced in a time-dependent manner. Interestingly, Vg2 gene was more susceptible than Vg1 to trace heavy metal exposure. This finding indicates that P. nana Vgs provide a potential indicator for assessing the toxic effect of heavy metals. In addition, we suggest P. nana as a potential model species for risk-assessment to environmental pollutants in brackish water.

The complete mitochondrial genome of the cyclopoid copepod Paracyclopina nana: A highly divergent genome with novel gene order and atypical gene numbers

In this paper, we describe the complete mitogenome of the cyclopoid copepod Paracyclopina nana with emphasis on the highly rearranged gene order and high divergence against published copepod mitogenomes. The P. nana mtDNA is 15,981 bp in length (70.9% AT) and consists of 37 genes (12 protein-coding genes, 2 rRNAs, 23 tRNAs) that are atypical for metazoan mitogenomes. Unusually, it contains an extra tRNA (tRNA-Ala) but it does not contain the ATPase 8 gene. The P. nana mitogenome has a long putative control region with high AT content (1351 bp, 77.0% AT). The Cyt b was considerably short in length, compared to other crustaceans. Compared to typical mitogenomes of arthropods and copepods, the gene order of the P. nana mitogenome is highly rearranged with a novel gene structure. In addition, P. nana has highly divergent mt genes (mostly less than 50%), judged by amino acid substitution. We present the first complete mitogenome sequence from a cyclopoid copepod, thereby increasing our understanding of copepod and crustacean evolution from the mitochondrial point of view.

기수산 요각류 Paracyclopina nena의 배양을 위한 최적 미세조류의 선별

This study selected the optimal microalgal species for mass culture of a brackish water copepod Paracyclopina nana. Fifteen microalgal species were tested to examine nauplius production and the survival and maturation of brood females. Total and daily nauplius production were highest in P. nana fed Tetraselmis suecica followed Isochrysis galbana, Dunaliella tertiolecta, and Phaeodactylum tricornutum. With a monospecific microalgal diet, the total density was highest with P. nana fed I. galbana, at 63.3 inds./mL. With a mixed microalgal diet, the total density of P. nana fed T. suecica+I. galbana was higher than that fed other mixed diets, although there was no difference between a monospecific diet of I. galbana and a mixed diet of T. suecica+I. galbana. Examining the fatty acid composition of P. nana, the eicosapentaenoic acid (EPA) was highest in P. nana fed T. suecica at 5.4% while the docosahexaenoic acid (DHA) content was highest I. galbana diet at 31.9%. Although no DHA was detected in T. suecica, P. nana fed this microalgal species had a high DHA composition of 24.3%. We suggest that the optimal microalgal species for the mass culture of P. nana is T. suecica which is easy to culture on masse and has a high linolenic acid content.

Effects of diets on the growth of the brackish water cyclopoid copepod Paracyclopina nana Smirnov

This study was carried out in individual cultures and in community cultures to investigate the effects of various diets (5 single diets: Phaeodactylum tricornutum (PHA), Isochrysis galbana (ISO), Tetraselmis suecica (TET), Marine Chlorella (MCH), condensed freshwater Chlorella (FCH), and 2 mixed diets: TET + ISO, TET + PHA) on the mass culture of cyclopoid copepod, Paracyclopina nana. In the individual cultures, fecundity of female P. nana fed the two mixed diets (TET + ISO, TET + PHA) was significantly higher than the fecundities of female P. nana fed the five single diets. The fecundity of the female P. nana fed PHA was lower than that fed TET and ISO. Also, P. nana nauplii fed TET, ISO and the two mixed diets developed to adult, however no nauplii developed into adult when fed PHA, FCH or MCH. In the community cultures, specific population growth rate of P. nana fed PHA was significantly lower than the specific population growth rate of P. nana fed TET, ISO and the two mixed diets. P. nana fed FCH and MCH showed negative growth and eventually all stages died on the 11th day. Our results suggest that the TET, ISO and TET + ISO diets could be the optimum diet for mass culture of P. nana. Our growth data suggest that P. nana has the potential for mass culture as a live feed organism for fish larvae.

수온과 염분에 따른 5종 요각류의 성장과 생산력

This study investigated the productivity and growth of copepods, Sinocalanus tenellus 2 strains, Paracyclopina nana 3 strains, Apocyclops royi 2 strains, Tachidius triangularis 1 strain and Tigriopus sp. 1 strain at different temperatures <TEX>$(24,\;28\;and\;32^{\circ}C)$</TEX> under 15 psu and various salinities (10, 20, 30 psu) at <TEX>$28^{\circ}C$</TEX> for an individual culture. And the mass culture was carried out to evaluate the production of these copepods in the 500 mL vessel. For an individual culture of copepod, survival period of a brood female tended to increase with the decrease of temperature, but was not significantly influenced by salinity. With an increase of temperature and a decrease of salinity, maturation period of nauplii in all species tended to decrease. Total nauglii production from a broodo female at <TEX>$24^{\circ}C$</TEX> was higoher than that from a brood .female at either 28 or <TEX>$32^{\circ}C$</TEX> for S. tenellus and at <TEX>$32^{\circ}C$</TEX> than either 24 or <TEX>$32^{\circ}C$</TEX> for A. royi Haenam stram, but was not influenced by temperature for another copepods. And total nauplii production from a brood female at 10 and 20 psu tended to be higher than that from a brood female at 30 psu, expect for Tigriopus sp. and P. nana Hwajinpo strain. Total nauplii production from a brood female was the highest in Tigriopus sp. (350 nauplii) at <TEX>$28^{\circ}C$</TEX> under 20 psu, followed by A. royi Haenam strain (187 nauplii) at <TEX>$32^{\circ}C$</TEX> under 15 psu and P. nana Hwajinpo strain (152 nauplii) at <TEX>$24^{\circ}C$</TEX> under 10 psu. In the mass culture of each copepod, P. nana was the most productive (26.6 mg dry weight) and this value was two and four times higher than productivity of Tigriopus sp. and A. royi, respectively.

Second record of Cyclopina kiraensis , a small, brackish-water cyclopoid copepod, in Japan

In the monthly zooplankton survey in Lake Nakaumi, Shimane Prefecture, conducted since July 1997, Cyclopina kiraensis occurred in the samples in July 1997 and July 1998. This species had not been recorded since the original description from the mouth of the Yahagi-furukawa River, Aichi Prefecture, in 1984. This paper is the second record of the species and is the first report of the species from the coast of the Sea of Japan. We describe environmental conditions of the habitat and the characteristics distinguishing this species from the morphologically allied species, Paracyclopina nana, which co-occurred in Lake Nakaumi.

北陸地方におけるプランクトンと塩分濃度との関係について

The writer has made a limnological investigation of five lakes and the rivers connecting with them in the Hokuriku district, with special reference to the relation between the salinity of the waters and the plankton species found there. The results obtained are as follows : 1. Forms of the watersA. Lakes1) Kahoku-gata…Mesohaline water2) Kita-gata…Fresh water-polyhaline water3) Imae-gata…Oligohaline water4) Kiba-gata (south-west) Shibayama-gata…Fresh waterB. Rivers a. Kakehashi-gawa1) at Sumiyoshi-bashi…α Mesohaline water2) at Shiodome-bashi at Mukaimotoori-shinbashi…Oligohaline water b. Kushi-gawa3) Muramatsu-cho…Fresh water-oligohaline water c. Shinhori-kawa4) at Genpei-bashi at Shiodome-suimon…Fresh water2. PlanktonThe plankton consist of 151 species, 20 Rotifera, 2 Cladocera, 6 Copepoda, 1 Bryozoa, 13 Protozoa, 31 Chlorophyceae, 3 Chyanophyceae and 75 Diatomaceae.The dominant and subdominant species occurring in this district are Sinocalanus tenellus, Paracyclopina nana, Pseudodiaptomus inopinus, Diaphanosoma brachyurum, Thermocyclops taihokuensis, Bosminopsis deitersi, Keratella valga, Brachionus calyciflorus var. dorcas and Ceratium hirundinella.Generally speaking, the plankton fauna in these waters, are divided into two groups according to the main representatives. One consists of Paracyclopina nana and Sinocalanus tenellus in L. Kahoku-gata and L. Kita-gata, both of which have the water of high salinity, and the other is represented by Diaphanosoma brachyurum, Bosminopsis deitersi and Thermocyclops taihokuensis in the water of low salinity, such as, L. Kiba-gata, L. Imae-gata and L. Shibayama-gata.As seen from the tables the zooplankton in the waters in question are richer in quantity than the scanty, phytoplankton, thongh the latter is rich in the number of species.Among the phytoplankton, Merismopedia sp., Anabaena sp., Pediastrum tetras, Ankistrodesmus falcatus var. mirabilis, Schroederia setigera, Scenedesmus dimorphus, S. denticulatus, S. longispina, S. maximus, Actinastrum sp., and Coelastrum sphaericum seem to adapt to brackish water.The diatoms are widely distributed in this district. The representative species found at Yoshizaki of L. Kita-gata is Melosira octogona and that at the Shiodome-bashi of the Kakehashi-gawa River is Nitzschia obtusa and N. obtusa var. scalpelliformis; that at Katayamazu by L. Shibayam-agata is Melosira varians. None of representative species is found in the other stations.