Takifugu Niphobles Research Articles

복섬 간장의 독성분과 pH 및 가열 조건에 따른 독성의 변화

우리나라 남해안 연안에 서식하는 복섬(Takifugu niphobles) 간장의 TTX유도체들을 활성탄 칼럼을 이용하여 부분 정제하고, Hydrophilic Interaction Liquid Chromatography(HILIC)를 사용한 LC/MS(SIM mode)로 분석하였으며, pH와 가열 조건에 따른 독성 변화를 조사하고 복섬 fillet으로 복국 조리시 독성의 분포를 조사하였다. 복섬 간장의 독성분은 LC/MS에 의하여 7개의 성분이 분석되었으며, 각 성분의 함량과 조성은 5,6,11-trideoxyTTX(34.0%, 1,029.6 n㏖/g), 6,11-dideoxyTTX(29.3%, 887.6 n㏖/g), TTX(22.1%, 667.8 n㏖/g), 4,9-anhydroTTX(11.2%, 339.3 n㏖/g), 11-deoxyTTX＋5-deoxyTTX(2.6%, 78.6 n㏖/g), 4-epiTTX(0.8%, 23.6 n㏖/g), 5,6,11-trideoxyTTX(34.0%), 6,11-dideoxyTTX(29.3%), TTX(22.1%), 4,9-anhydroTTX(11.2%), 4-epiTTX(0.8%)이었다. 복섬 간장 추출물 희석액의 독성은 pH에 따라 크게 변하여 pH 3에서 8.4 MU/mL로 최고의 독성을 나타내었고, 알칼리로 갈수록 독성이 감소하여 pH 10에서는 pH 3의 1/7(1.4 MU/mL)을 나타내었다. 각각의 pH(pH 5, 7, 9)에서 80℃, 100℃, 115℃를 유지하며 가열 시 온도는 높을수록, 시간은 길수록 독성은 감소하였다. 특히, 산성이나 중성에서는 독성이 완만하게 감소하는 경향을 보였으나, 알칼리 영역인 pH 9에서는 가열 10분 후에 80℃의 경우라도 최초 독성(79 MU/mL)이 1/2 이하로 급격히 감소하였으며, 115oC에서는 완전 소멸하였다. 복섬 개체별 fillet 중의 총 독량은 43.2～106.7 MU로 개체에 따라서 2.5배까지 독량의 차이를 나타내었으며, 복섬 가식부에 3배량의 물을 가하여 10분간 끓일 경우 총 독량의 64～78%는 국물 중으로 용출되어 나와 육에 남아있는 것보다 독성이 강하였다.

Isolation of halotolerant Lactococcus lactis subsp. lactis from intestinal tract of coastal fish

We isolated lactic acid bacteria from the intestinal tract of the pufferfish Takifugu niphobles caught in Shimoda, Shizuoka, Japan by using MRS broth prepared with 50% seawater. Additional screening was carried out using phenotypic tests such as Gram staining, cell morphology, catalase, oxidase and fermentation of glucose. Subsequently 227 isolates screened by the phenotypic tests were subjected to species-specific PCR for Lactococcus lactis, resulting in four positive isolates. The 16S rRNA gene sequences from three isolates were highly similar to that of L. lactis subsp. lactis (DNA database accession number M58837), while that of one isolate was identical to that of Leuconostoc mesenteroides ( AB023246). These isolates were characterized by API 50 CH for carbohydrate fermentation and other phenotypic criteria for salt tolerance, and the characteristics were compared with those of L. lactis subsp. lactis from a cheese starter culture. The carbohydrate fermentation profiles of these isolates were characteristic of L. lactis subsp. lactis strains, whereas the tolerance of these isolates to salt was higher than that of L. lactis subsp. lactis from the cheese starter culture: the new L. lactis isolates showed high salt tolerance in MRS-agar plates containing 200% seawater or 6% sodium chloride. This is the first report of the isolation of halotolerant strains of L. lactis subsp. lactis from a marine environment.

한국 연안산 졸복(Takifugu pardalis)과 복섬(Takifugu niphobles)의 독성

The toxicity of two species of puffer fish, Takifugu pardalis and T. niphobles, collected from the coastal regions of Korea was determined using a mouse bioassay. In T. pardalis collected at Tongyeong, the proportion of toxic specimens containing <TEX>${\geq}10MU/g$</TEX> exceeded 90% for the skin, fins, liver, intestine, ovary, and gallbladder, 11.1% for the testis, and 6.9% for the muscle. In each of the organs, the highest toxin levels were several tens (14-39) of mouse units (MU) per gram in the muscle, testis, and eyeball, but thousands (1,444-5,755) of MU per gram in the skin, liver, intestine, ovary, and gallbladder. The organs of T. pardalis exhibited remarkable variation in toxicity. In T. niphobles, the proportion of toxic specimens exceeded 90% for the ovary and skin, 60-80% for the fins, liver, intestine, and gallbladder, and 4.5% for the muscle; no toxicity was detected in the testis or eyeball using the mouse bioassay. The highest toxin levels were thousands (2,291-7,777) of MU per gram in the liver, intestine, ovary, and gallbladder, hundreds(146-328) of MU per gram in the skin and fins, and 18 MU/g in the muscle. Takifugu niphobles toxicity also exhibited remarkable regional variation. The toxicity in the edible muscle of T. pardalis and T. niphobles was at acceptable levels for human consumption, while the toxicity of the skin of both species of puffer fish was very high, so that care must be taken when used for human consumption.

Structure of neurohypophysial hormone genes and changes in the levels of expression during spawning season in grass puffer ( Takifugu niphobles)

Vasotocin (VT) has been shown to influence various aspects of social and sexual behaviors in a broad range of vertebrate species, but less is known about the mechanisms through which this peptide modulates behavior. Additionally, much less is known about roles of isotocin (IT) in regulation of behavior. Grass puffer, Takifugu niphobles, has unique spawning behavior; spawning occurs on beach only for several days around the spring tide and is conducted by a group of 10–60 individuals, of which one is female. As a first step toward investigating the roles of VT and IT in this species’ spawning behavior, we determined the structures of the VT and IT genes from grass puffer using the genome resources of the closely related tiger puffer and green puffer. We then used these sequences to develop real-time PCR assays and examined changes in expression of the VT and IT genes over the spawning season. The structures of VT and IT genes are well conserved among three puffer species. Particularly, the sequence similarities between grass and tiger puffers were very high not only in the coding region (85–99%), but also in the non-coding regions (92–98%) that include the 5′-upstream regions. The levels of expression of VT gene increased in the brain of pre-spawning females. The levels of VT mRNA in the spawning females tended to be higher than that in the spawning males. In contrast, the levels of IT mRNA did not show such variation. The present results suggest that VT gene expression augments in the brain of females during the spawning period. The unique spawning behavior of grass puffer provides a useful model for studying the molecular mechanism of sexual behavior utilizing the genome resources of tiger puffer.

Identification of novel genes related to tetrodotoxin intoxication in pufferfish

To investigate the genes related to the biosynthesis or accumulation of tetrodotoxin (TTX) in pufferfish, mRNA expression patterns in the liver from pufferfish, akamefugu Takifugu chrysops and kusafugu Takifugu niphobles, were compared by mRNA arbitrarily primed reverse transcription-polymerase chain reaction (RAP RT-PCR) with fish bearing different concentrations of TTX and its derivatives. RAP RT-PCR provided a 383 bp cDNA fragment and its transcripts were higher in toxic than non-toxic pufferfish liver. Its deduced amino acid sequence was similar to those of fibrinogen-like proteins reported for other vertebrates. Northern blot analysis and rapid amplification of cDNA ends (RACE) revealed that the cDNA fragment of 383 bp was composed of at least three fibrinogen-like protein (flp) genes, flp-1, flp-2 and flp-3. Relative mRNA levels of flp-1, flp-2 and flp-3 showed a linear correlation with toxicity of the liver for two pufferfish species.

Cloning and polymorphism analysis of intron 2 of the GH gene in Takifugu

Size and nucleotide polymorphisms of intron 2 of the growth hormone (GH) gene was studied in 82 individuals from Takifugu obscurus, Takifugu rubripes and Takifugu niphobles with PAGE, SSCP and cloning. Results showed that there were nine length variants (A~I) in these fishes, ranging from 271351 bp, with a frequency of variation of 24.22%. Sequence analysis of the 9 length variants showed the average percentages of the four bases (ATG and C) were 17.15, 20.77, 37.38 and 24.70, respectively, and the difference between GC content (45.47) and AT content (54.53) was not remarkable. Length variation was mainly due to the variable number of microsatellite TCTG repeats (N=20 approximately 40). Further sequence comparison revealed 4 substitution sites: a (C-->A) transversion at nucleotide 103 and 3 transitions 83(C-->T), 101(A-->G) and 296(G-->A), respectively. Phylogenetic analysis of these length variants placed DD and II into one group first, which was subsequently joined by GG and AA, BB and CC, EE and HH were then clustered together, FF was joined last. Thus, intraspecific variations were much smaller than interspecific variations for the intron 2 of the GH gene.

Involvement of host recognition by oncomiracidia and post-larval survivability in the host specificity of Heterobothrium okamotoi (Monogenea: Diclidophoridae)

Heterobothrium okamotoi, a monogenean gill parasite, shows high host specificity for tiger puffer, Takifugu rubripes. In the present study, in vivo and in vitro experimental infections were conducted using various fish species, including T. rubripes, to understand the mechanisms of specificity. In in vivo experiments, T. rubripes, grass puffer, Takifugu niphobles, olive flounder, Paralichthys olivaceus, and red sea bream, Pagrus major, were exposed to oncomiracidia of H. okamotoi labelled with a fluorescent dye, 5- (and -6) carboxyfluorescein diacetate succinimidyl ester, and the numbers of parasites on the gills and skin were recorded at intervals. Oncomiracidia were attached to gills and skin of all the experimental fish species immediately after exposure, and the infection intensity on T. rubripes was higher than that on T. niphobles and much higher than those on the other two species. After 2 days, the attached parasites remained on the gills of T. rubripes, but disappeared from the other hosts. During in vitro experiments, gill filaments excised from seven different fish species (four fish species used in the in vivo experiments and panther puffer, Takifugu pardalis, southern flounder, Paralichthys lethostigma and spotted halibut, Verasper variegates) were exposed to oncomiracidia and the attachment to each fish species and subsequent larval behaviour was observed. The percentage of post-larvae that attached to T. rubripes was slightly higher than those which attached to congeneric fish species and much higher than those of non-tetraodontid fish species. In vivo and in vitro experiments demonstrated that oncomiracidia of H. okamotoi have an affinity for their natural host, T. rubripes, and congeneric fish species. The disappearance of attached post-larvae from ‘alien’ hosts within 2 days during in vivo experiments suggested that host recognition by oncomiracidia and subsequent post-larval survivability are involved in the host specificity of H. okamotoi.

여수 연안 승망 어장에서 어획된 어업생물의 계절별 분포특성

A study on the species composition and seasonal variations of fishery creatures caught by a funnel net was carried out in the coastal water off Dolsan Island, Yeosu from 2002 to 2003. During the study period, a total of 23 fishery creatures species were caught. Seabream(Acanthopagrus schlegeli), sea bass(Lateolabrax japonicus), mullet(Mugil cephalus), puffer(Takifugu niphobles) and rockfish(Sebastes inermis) predominated. These five species accounted for 85.1% of the total number of fishery creatures caught. Seasonal peaks of number of species occurred in summer, while those of number of individuals occurred in autumn. The lowest number of species and individuals were observed in winter. The large annual variation of diversity indices were observed from May to August. These large annual variation of diversity indices were mainly due to predominance of seabream, sea bass and mullet which accounted for most of all fishery creatures caught. The seasonal variations of fishery creatures showed that sea bass and mullet were caught mainly from spring to summer, seabream and puffer were caught mainly in autumn, and rockfish and brotula(Hoplobrotula armata) were caught mainly in winter.

Detection of tetrodotoxin (TTX) from two copepods infecting the grass puffer Takifugu niphobles: TTX attracting the parasites?

In May 2002, two parasitic copepods, Pseudocaligus fugu and Taeniacanthus sp., were collected from the body surface and gill of the grass puffer Takifugu niphobles, respectively, in Takehara city, Hiroshima Prefecture, faced with Seto Inland Sea located in the western part of Japan. To them was added 5 ml of 0.1% acetic acid, then the suspension was subjected to ultrasonic disruption with an ultrasonicator for 10 min. The resulting mixture was heated in a boiling water bath for 10 min, and then centrifuged. The supernatant was concentrated under reduced pressure, and loaded on to a Sep-Pak plus C18 Environmental Cartridge (Waters). The unbound fraction was analyzed by HPLC and gas chromatography–mass spectrometry (GC–MS) for tetrodotoxin (TTX). It was rather unexpectedly revealed from these results that this fraction was comprised of TTX and its analogues. As far as we know, this is the first record to show the existence of TTX in the copepods. In addition, relationships between the more and less than the average number of the two parasites and the toxicity of its skin mucus of the host were examined by student's t-test. In P. fugu, the average number per host was 13.9, and those are 520.7 ( n=9) and 269.0 MU/g ( n=22), respectively. A highly significant difference between them was detected at p-value 0.0011. In contrast, as for Taeniacanthus sp., the average number was 2.7, and those were 338.0 ( n=14) and 345.5 MU/g ( n=17), respectively. No significant difference was detected in Taeniacanthus sp. The high host-specificity of P. fugu on the toxic puffer and the present bioassay of its skin mucus suggest a possibility that TTXs may attract the parasite.

Molecular identification of intestinal microflora in Takifugu niphobles

We investigated the intestinal microflora of coastal fish including Takifugu niphobles using both culture techniques and library cloning. As a result, the numbers of bacteria appeared on agar media were 1.0 × 10 4 to 1.4 × 10 9 CFU/g (colony forming units/gram), whereas those of total bacteria stained with 4′,6-diamidino-2-phenylindole were 4.7 × 10 10 to 1.9 × 10 11 cells/gram, irrespective of different fish species. In addition, the culture technique showed that the intestinal microflora in all specimens was mainly composed of the genus Vibrio. In contrast, the direct count method showed that spirochaetes with length of 2.5-4.5 μm were present in the intestinal contents of T. niphobles at high densities, whereas such bacteria could not be detected in those of other fish species. Library cloning yielded the sequences of 16S rRNA genes that were divided into seven taxonomic categories of bacteria including Actinobacteria, Bacilli, Clostridia, Gammaproteobacteria, Mollicutes, Spirochaetes and an unclassified bacterial group. These results demonstrate that the molecular diversity of the intestinal bacteria in T. niphobles based on the clone library method reflects the direct observation by fluorescence microscopy to some extent.

Food habits of fishes in the surf zone of a sandy beach at Sanrimatsubara, Fukuoka Prefecture, Japan

To clarify the feeding habits of fishes in surf zones, the gut contents of 19 fish species collected in the surf zone of a sandy beach at Sanrimatsubara, western Japan, were examined. Ontogenetic changes in food preference were recognized in seven species (Mugil cephalus cephalus, Lateolabrax latus, Sillago japonica, Paralichthys olivaceus, Paraplagusia japonica, Takifugu poecilonotus, and Takifugu niphobles). A cluster analysis based on dietary overlaps showed that the surf zone fish assemblage comprised six trophic groups (zooplankton, benthic and epiphytic crustacean, detritus, polychaete, fish, and insect feeders). Of these, the most abundant trophic group was zooplankton feeders, along with benthic and epiphytic crustacean feeders.

Reversible frequency-dependent predation of a puffer, Takifugu niphobles (Pisces: Tetraodontidae), related to spatial distribution of colour-polymorphic prey

The puffer Takifugu niphobles is a top predator of hard-shelled prey such as molluscs; its predatory tactics may affect the evolution of prey coloration. Two hypotheses concerning its foraging were tested: (1) T. niphoblesshows frequency dependence in foraging colour-polymorphic prey, and (2) such dependence reverses in response to changes in prey distribution. Captive fish were provided with 70 artificial prey, coloured either dark brown or pale brown, at four frequencies (1 : 4, 2 : 3, 3 : 2, 4 : 1) and in two distribution patterns (uniform and aggregated). When prey were uniformly distributed, frequency and feeding rate significantly influenced colour preference: the common morph was consumed more. When prey were aggregated, frequency significantly affected preference only when the feeding rate was low, in which case the rare morph was consumed more. Thus both hypotheses were supported. The impact of T. niphobles's frequency-dependent predation and its reversal on the colour evolution of prey species, especially molluscs, is discussed. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81, 197–202.

How do multiple environmental cycles in combination determine reproductive timing in marine organisms? A model and test

Summary Each of the multiple environmental cycles – the light–dark, tidal, semilunar, lunar and seasonal cycles – may have an independent, specific effect on reproductive timings of marine organisms and can alone or in combination produce a variety of temporal reproductive patterns. Assuming that each ecological interaction with these fluctuating environmental cycles generates a unique functional relationship between a component of fitness and the timing of reproduction, a model is proposed that predicts that all fitness components are multiplicative and therefore the reproductive timing is entrained or driven by a cycle(s) having a sharp functional curve of the relevant fitness component. According to this model, many of the reproductive patterns, ranging from diel to lunar, commonly seen in marine organisms were explained by changing relative kurtosis among functional curves of fitness components. Each curve could also differ in its optimum and skewness, making various intermediates and modifications possible. As a model system for the model to be applied, intraspecific variation in the timing of spawning by a puffer, Takifugu niphobles (Jordan &amp; Snyder) was examined. The patterns of daily variation in a day's spawning time within a population and geographical variation in spawning days among populations indicated that (1) the semilunar cycle (i.e. spring–neap tide cycle) has no direct influence on spawning days, (2) a combination between the functional curves of the fitness components associated with the light–dark and tidal cycles produce an apparent biweekly, semilunar spawning rhythm, (3) the curves may be skewed toward earlier and later times, respectively, and (4) their form may differ among populations. This model approach argues that to understand the ecology and evolution of temporal patterns of reproduction, one must properly decouple and evaluate the form of the functional curve of a fitness component associated with each of the multiple environmental cycles.

Partial Purification of Kuchijirosho Causative Agent by Sodium lotalamate Density Gradient Centrifugation

To purify the kuchijirosho causative agent derived from brains of kuchijirosho-affected tiger puffer Takifugu rubripes, the method of density gradient centrifugation using iodinated contrast medium, Angio-Conray (solium iotalamata solution), was used. The extracts of kuchijirosho-affected brains were loaded on 3-55% gradient of Angio-Conray, and centrifuged at 280, 000 ×g for 2 h. The lethal activity to grass puffer Takifugu niphobles was found in a fraction with a density around 1.096 g/cm3. The infectivity of the extracts of kuchijirosho-affected brains was lost by treatment with ether, UV-irradiation, β-propiolacton or proteinase K.

Gluconacetobacter Persimmonis KJ145T를 이용한 Bacterial Cellulose및 식초의 동시 생산에 관한 연구

The living Glass puffers, Takifugu niphobles (Bogseom as Korean name), 10 specimens, were purchased at Tongyeong traditional fisheries market every month from November, 2001 to October, 2002, and tested anatomical distribution of the toxicity such as muscle, skin, intestine, liver and ovary by mouse bioassay method. Significant seasonal variations of the toxicity were not shown in muscle, skin, intestine and liver except having lower toxicity in spawning season (May and June) than non-spawning seasons. 92 specimens (76.7%) out of 120 ones were non toxic (below 10 MU/g) for the edible and 28 ones (23.3%) were weakly toxic (10 MU/g~100 MU/g) for the non-edible in muscle ranged between 0 MU/g and 46.4 MU/g. All of those toxicity were shown over 10 MU/g in skin for the non-edible in skin ranged from 10.0 MU/g to 674.4 MU/g. Toxicity range in intestine and liver was varied between non-toxic and strongly toxic (over 1,000 MU/g) for individual specimens. Toxicity range of the ovary found only in May (7 specimens) and June (1 specimens) was 84.2 MU/g to 2,191.3 MU/g.

가덕도 주변 해역 어류의 종조성과 계절 변동 -3. 꽃게통발에 의해 채집된 어류-

가덕도 주변 해역에 서식하는 어류의 종조성과 계절 변동을 알아보기 위해 꽃게통발을 이용하여 어류를 채집하였다. 1998년 1월부터 12월까지 매월 소조기에 채집된 어류는 26과 49종이었다. 붕장어 (Conger myriaster)가 가장 많이 채집되었으며, 그 다음으로 볼락 (Sebastes inermis), 쥐노래미 (Hexagrammos otakii), 노래미(H. agrammus), 쥐치 (Stephanolepis cirrhifer), 문절망둑 (Acanthogobius flavimanus) 등이 많이 채집되었는데, 이들 6종이 전체채집 개체수와 생체량의 <TEX>$67.1\%$</TEX>와 <TEX>$69.4\%$</TEX>를 차지하였다. 그 밖에도 말쥐치 (Thamnaconus modestus), 복섬 (Takifugu niphobles), 그물코쥐치 (Rudarisu ercodes), 그물베도라치 (Dictyosoma burgeri), 횐꼬리볼락 (Sebastes longispinis), 능성어 (Epinephelus septemfasciatus) 등이 비교적 많이 채집되었다. 채집 종수는 11월에 28종으로 가장 많았고, 7월에 14종으로 가장 적었다. 개체수와 생체량은 모두 3월에 가장 높은 값을 보였으며, 개체수는 7월에 생체량은 9월에 가장 낮은 값을 나타냈다. 종다양도지수는 연중 큰 변동이 없는 편이었으나, 채집 어종수가 적고 쥐치와 말쥐치가 극우점하였던 8월에 가장 낮은 값을 보였다. The monthly collected fish samples by crab pots were analyzed in order to study the species composition and seasonal variation of fish assemblage in the coastal water off Gadeok-do, Korea in 1998, During the study period, 49 species of fishes representing 26 families were collected, The dominant species were Conger myriaster, Sebastes inermis, Hexagrammos otakii, H. agrammus, Stephanolepis cirrhifer and Acanthogobius flavimanus. These 6 dominant species accounted for <TEX>$67.1\%$</TEX> and <TEX>$69.4\%$</TEX> in the number of individuals and biomass, respectively. The secondary importance species were Thamnaconus modestus, Takifugu niphobles, Rudarius ercodes, Dictyosoma burgeri, Sebastes longispinis and Epinephelus septemfasciatus. The highest number of species was collected in November, and the number of individuals and biomass were highest in March. But the lowest numbers of species and individuals were collected in July and the lowest biomass in September, Although the species diversity indices varied little monthly, the lowest value was recorded in August because of small number of species and predominance of 5. cirrhifer and T. modestus.

Fish Communities in the Surf Zone of a Protected Sandy Beach at Doigahama, Yamaguchi Prefecture, Japan

Fish communities comprising postlarval to early adult stages were studied in the surf zone of a protected sandy beach, with runnels and a low tide terrace, at Doigahama, Yamaguchi Prefecture, western Japan. One elasmobranch and 100 teleost species, represented by a total of 17608 individuals (1·85–785mm in TL), were collected by fine and coarse meshed beach seines from May 1994 to April 1999. Species richness, abundance and biomass were greater during the evenings as well as in the warmer seasons (May to October). Larval and smaller juvenile ichthyofauna (collected mainly by fine-mesh seine) was relatively poor compared to larger juvenile ichthyofauna (coarse-mesh seine). Tidal effect was observed in the fine-mesh seine samples, whereas no tide-related trends were evident in the coarse-mesh seine samples. Effects of time of the day and tide on the species diversities were not so evident in both seines. Dominant species were classified according to the developmental stages occurring in the surf zone, as follows: Type-I: Postlarval (transformation) stage (Plecoglossus altivelis altivelis,Sardinops melanostictus , Enneapterygius etheostomus, Tripterygion bapturum, Luciogobius sp.). Type-II: Juvenile stage (Lateolabrax latus, Trachurus japonicus, Gerres oyena, Acanthopagrus schlegeli, Sparus sarba, Girella punctata, Mugil cephalus cephalus, Paralichthys olivaceus, Tarphops oligolepis, Heteromycteris japonica). Type-III: Postlarval and juvenile stages (Spratelloides gracilis, Engraulis japonicus, Gobiidae sp.1). Type-IV: Juvenile and early adult stages (Sillago japonica, Paraplagusia japonica). Type V: Postlarval to early adult stages (Takifugu niphobles). It is considered that the surf zone at Doigahama functions as a nursery area, particularly as a feeding place for larger juveniles than as a shelter for larvae and smaller juveniles.

가덕도 주변 해역 어류의 종조성과 계절 변동 -2. 삼각망에 의해 채집된 어류-

The monthly collected fish samples by three sides tyke nets were analyzed in order to study species composition and seasonal variation of fish assemblage in the coastal water off Gadeok-do, Korea through a year of 1998, During the study period, a total of 136 fish species of 69 families were collected. Trachums japonicus, Konosims punctatus and Mugil cephaus were three dominant species in the fish assemblage and they accounted for and in the number of individuals and biomass, respectively. Fish species of secondary importance in abundance were Leiognathus nuchalis, Takifugu niphobles, Somber japonious, Trichiurus lepturus, Chelon affinis, Apogon lineatus, Nibea aibiflora and Acanthopagrus schlegeli. The highest number of species was collected in July and the lowest in february. Abundance was high in spring, and low in winter. Species diversity indices showed that the fish assemblage was less diverse in spring than any other seasons.

Are puffer fish more toxic in their spawning seasons?

It has been a common belief that all puffer fishes are more toxic in their spawning seasons, perhaps to protect their fertilized eggs. However, the current study of two puffer fishes, Takifugu niphobles (Jordan and Snyder) and Takifugu alboplumbeus (Richardson), collected in Hong Kong waters continuously for over a year and bioassayed for toxicity in terms of mouse units (MU), showed the contrary. Their annual spawning seasons (evident from the enlargement of the gonads and the presence of eggs in the ovary) were found to be from October to February (4 consecutive months) and December to February (2 consecutive months), respectively. In both species, the ovaries were highly toxic (100–1,000 MU/g) only in their non-spawning seasons and they became weakly toxic (10–100 MU/g) in their spawning seasons; unlike the ovaries, liver and intestine, the flesh and the skin did not have marked annual toxicity patterns. Their flesh was basically non-toxic (less than 10 MU/g) throughout the whole year. The testes, which were only developed in the spawning seasons, were also found to be non-toxic.

Identification of Toxin and Fish Species in Cooked Fish Liver Implicated in Food Poisoning

ABSTRACT: The cooked fish liver retained by the victims was assayed for toxicity and mitochondrial DNA. Meanwhile, 8 live specimens of puffer Takifugu niphobles were also assayed. The toxicity of cooked fish liver was 280 ± 20 mouse units per gram (MU/g). All specimens of T. niphobles showed high toxicity (more than 850 MU/g) in the liver. The toxin from cooked fish liver and liver of T. niphobles was identified to be tetrodotoxin. The cooked fish liver and fresh liver of T. niphobles showed the same sequence genotype and the same single restriction site for Bsa I. Therefore, the species of cooked fish liver was suggested as T. niphobles.