Dentex Tumifrons Research Articles

Maturation and Spawning of Yellowback Seabream Dentex tumifrons in the Coastal Waters of Korea

Maturation and Spawning of Yellowback Seabream Dentex tumifrons in the Coastal Waters of Korea

A new and two known species of Hatschekia Poche, 1902 (Copepoda, Siphonostomatoida, Hatschekiidae) parasitic on Japanese fishes

Abstract Hatschekia laeopsi sp. nov., H. branchiostegi Yamaguti, 1939 and H. pagrosomi Yamaguti, 1939 are (re-)described based on specimens collected from the branchial lamellae of three Japanese fishes, Laeops kitaharae (Smith & Pope, 1906) (Pleuronectidae), Branchiostegus japonicus (Houttuyn, 1782) (Malacanthidae), and Dentex tumifrons (Temminck & Schlegel, 1843) (Sparidae), respectively. The free-living stages of H. branchiostegi are described for the species for the first time.

Length-weight and length-length relationships for six commercial fishes from southern Korean waters

Summary Presented are the relationships between total length and weight, and between total length and standard length for six commercial fishes collected twice a month from local fish markets in southern Korea between 2005–2006 for Acanthopagrus schlegelii (Bleeker, 1854), Hexagrammos agrammus (Temminck & Schlegel, 1843) and Hexagrammos otakii (Jordan & Starks, 1895), and monthly in 2004 for Dentex tumifrons (Temminck & Schlegel, 1843), Doederleinia berycoides (Hilgendorf, 1879) and Scomberomorus niphonius (Cuvier, 1832). The LWR for D. tumifrons is estimated for the first time, and a new maximum length was recorded for S. niphonius. All total length and weight relationships were significant (all r2 > .953). The values of exponent b, estimated using simple linear least squares of log-transformed weight and length data, ranged from 2.945 to 3.317.

TheCardiovascularandNeurotoxicEffectsofthe VenomsofSixBonyandCartilaginousFishSpecies.

Fish venoms are often poorly studied, in part due to the difficulty in obtaining, extracting, and storing them. In this study, we characterize the cardiovascular and neurotoxic effects of the venoms from the following six species of fish: the cartilaginous stingrays Neotrygon kuhlii and Himantura toshi, and the bony fish Platycephalus fucus, Girella tricuspidata, Mugil cephalus, and Dentex tumifrons. All venoms (10–100 µg/kg, i.v.), except G. tricuspidata and P. fuscus, induced a biphasic response on mean arterial pressure (MAP) in the anesthetised rat. P. fucus venom exhibited a hypotensive response, while venom from G. tricuspidata displayed a single depressor response. All venoms induced cardiovascular collapse at 200 µg/kg, i.v. The in vitro neurotoxic effects of venom were examined using the chick biventer cervicis nerve-muscle (CBCNM) preparation. N. kuhlii, H. toshi, and P. fucus venoms caused concentration-dependent inhibition of indirect twitches in the CBCNM preparation. These three venoms also inhibited responses to exogenous acetylcholine (ACh) and carbachol (CCh), but not potassium chloride (KCl), indicating a post-synaptic mode of action. Venom from G. tricuspidata, M. cephalus, and D. tumifrons had no significant effect on indirect twitches or agonist responses in the CBCNM. Our results demonstrate that envenoming by these species of fish may result in moderate cardiovascular and/or neurotoxic effects. Future studies aimed at identifying the molecules responsible for these effects could uncover potentially novel lead compounds for future pharmaceuticals, in addition to generating new knowledge about the evolutionary relationships between venomous animals.

Isolation and characterization of acid-soluble collagen from the scales of marine fishes from Japan and Vietnam

Acid-soluble collagen (ASC) was successfully extracted from the scales of lizard fish (Saurida spp.) and horse mackerel (Trachurus japonicus) from Japan and Vietnam and grey mullet (Mugil cephalis), flying fish (Cypselurus melanurus) and yellowback seabream (Dentex tumifrons) from Japan. ASC yields were about 0.43–1.5% (on a dry weight basis), depending on the species. The SDS–PAGE profile showed that the ASCs were type I collagens, and consisted of two different α chains, α1 and α2, as well as a β component. ASC of horse mackerel from Vietnam contained a higher imino acid level than that from Japan. ASC denaturation temperature (Td) ranged from 26 to 29°C, depending on fish species and imino acid content (p<0.01). Maximal solubility of individual collagens was observed at pHs 1–3. Collagen solubility decreased sharply at NaCl concentrations >0.4M, regardless of fish type.

Genetic structure of yellowback sea bream Dentex tumifrons in China inferred from AFLP data

The resource of yellowback sea bream Dentex tumifrons has declined very quickly in China due to overfishing since the 1970s. In this study, a total of 122 wild samples of the yellowback sea bream from marine waters of Qingdao (QD), Zhoushan (ZS), Shenzhen (SZ), and Beihai (BH) were analyzed using amplified fragment length polymorphism (AFLP). A total of 265 putative loci were detected by five AFLP primer sets, 116 of which were polymorphic (43.8%). The locality with the highest proportion of polymorphic loci (PPL, 29.4%) and number of polymorphic loci (PL, 78) was ZS, whereas that with the lowest was BH, in which a PL of 64 and a PPL of 24.2% were detected. The locality with the highest Nei’s gene diversity was also ZS with a value of 0.2237, whereas the locality with the lowest was BH with a value of 0.1905. Analysis of Wright’s Fst indicated that there existed distinct genetic differentiation among four localities (P≤0.001). It is speculated that there exist at least four distinct geographic subpopulations of the sea bream in Chinese waters. This research provides some of the first published AFLP data in the species.

Behaviour of connective tissue in fish surimi on fractionation by sieving

The surimis prepared from the three fish species, red barracuda Sphyraena pinguis, yellow sea bream Dentex tumifrons, and spotted shark Mustelus manazo, were fractionated by sieving through a 30-mesh stainless steel sieve. Chemical analyses revealed significant differences in the collagen content among the residual fraction on the sieve (fraction A), the passed fraction (fraction C), and the original surimi before sieving (fraction B): the fractions A and B showed values 10–20 and 5–10 times higher than those of the fraction C, respectively, for all the species examined. Histological observation indicated the richness of the thick connective tissues derived from myocommata in fractions A and B, while thick connective tissue was hardly observed in fraction C. These results suggested that the present fractionation method may have an effect of reducing the collagen content to about 10–20% of the original value, and that a large part of collagen in fish surimi exists in the relatively thick connective tissue, probably derived from myocommata.

Reproductive cycle of yellow sea bream Dentex tumifrons in Wakasa Bay, the Sea of Japan off central Honshu

To determine the spawning season and reproductive cycle of the yellow sea bream, Dentex tumifrons, in Wakasa Bay, in the Sea of Japan off central Honshu, seasonal change in the gonadosomatic index (GSI) was examined and histological observations of both ovaries and testes were conducted. The female GSI gradually increased from May, maintained a high level between that vitellogenesis began from May and developed until September. Spent fish began to be observed in October and all the fish collected in December were spent. There was only one peak in the seasonal change in GSI of males and females in Wakasa Bay. Thus, yellow sea bream spawn only in autumn in Wakasa Bay. Differences in the reproductive cycle and number of spawning seasons were found between the two different latitudinal areas, Wakasa Bay and the East China Sea (low latitudinal area) where the spawning seasons were spring and autumn. An increase in water temperature is an important factor to initiate gonadal maturation (recrudescence) and is terminated by the short day-length in Wakasa Bay.

Age, Growth and Reproductive Characteristics of the Yellow Sea Bream &lt;i&gt;Dentex tumifrons&lt;/i&gt; in the East China Sea

Age, Growth and Reproductive Characteristics of the Yellow Sea Bream &lt;i&gt;Dentex tumifrons&lt;/i&gt; in the East China Sea

Cytogenetical studies on fishes, IV. Karyotypes of six species in the sparoid fishes.

All six sparoid fish species (Pagrus major, Evynnis japonica, Dentex tumifrons, Acanthopagrus schlegeli, A. latus and Sparus sarba) studied here showed a diploid chromosome number of 48. Although the total numbers of chromosomes in these species were identical, the numbers of the acrocentrics, subtelocentrics and submetacentrics were different from each other. Thus, they had different numbers of chromosome arms such as 50, 52, 58 and 60 (Table 2). Based on the karyotype analysis the sparoid species can be classified roughly into two groups according to the number of biarmed chromosomes; one of them had 2 or 4 biarmed chromosomes as found in P. major, E. japonica and D. tumifrons, and the other one had 10 or 12 biarmed chromosomes as seen in A. schlegeli, A. latus and S. sarba. The secondary constrictions were found in No. 4 chromosomes of two species (A. schlegeli and A. latus). Although a heteromorphic chromosome pair was found in No. 1 chromosomes of P. major and E. japonica, it can not be identified at present whether this heteromorphic pair is sex chromosome or not.