• Applied Microscopy
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• v.27 no.4
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• pp.417-432
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• 1997

The structures of the fertilized egg envelope in three species of cichlidae, golden severum (Cichlasoma severum var.), convic cichlid (Cichlasoma nigrofasciatum) and discus (Symphysodon aequifasciatus) were investigated by routine light and electron microscopies. The fertilized eggs of all three species were of the non-transparent, ellipsoidal, adhesive and non-floted type. The egg envelopes have a single micropyle, which is thought to the pathway of sperm in the area of the animal pole. In golden severum, an outer surface of egg envelope was covered by a reticular layer, that of convic cichlid was covered by an amorphous reticular layer and that of discus was covered by a branched reticular layer. The fertilized egg envelopes consisted of two distinct layers, an adhesive outer layer and an inner layer, consisted of lamellae alternating with interlamellae of lower electron density, in all three species; an inner layer of golden severum was $15\sim17$ layers, that of convic cichlid was $14\sim16$ layers, and that of discus was $18\sim19$ layers.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.2
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• pp.184-189
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• 2016

We investigated physiological changes in the freshwater cichlid, fish Maylandia lombardoi in response to different calcium concentrations in rearing water. Four different calcium concentrations (0, 2, 4 and 8 mM) were prepared in rearing water by the addition of ionized calcium (CaO) to examine the effect of various calcium concentrations in rearing water on physiological changes in the cichlid fish, M. lombardoi. Total calcium concentrations in plasma and body increased in a calcium concentration-dependent manner and reached the maximum at 8-mM calcium concentration. Stress-related cortisol was significantly decreased in the 8-mM group compared to the control group (0 mM). Lysozyme activity also significantly decreased in the 8-mM group. These results suggest that CaO in rearing water increases calcium uptake in fish and affects the body by decreasing stress and improving immunity in fish.

• Development and Reproduction
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• v.20 no.3
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• pp.267-274
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• 2016

Cichlid fish species exhibit characteristic sexual behaviors according to not only reproductive stages but also social status. In a reproductive season, Astatotilapia burtoni males compete for females and a small number of dominant winners finally obtain the chance of spermiation. In addition to the characteristic behaviors, the dominant males have relatively bigger gonadotropin-releasing hormone 1 (GnRH1) neurons in the preoptic area (POA) of brain compared to those of subordinate males. Although the stimulatory effect of GnRH1 in vertebrate reproduction is well established, little is known about the triggering signal pathway to control GnRH1 neurons and GnRH1-mediated sexual behavior. In the present study, we evaluated the potential effect of TOR inhibitor rapamycin in relation to the cichlid male behaviors and GnRH1 neuron. After 14 h and 26 h of intraventricular injection of rapamycin, behavior patterns of chasing and courtship display did not show significant changes between rapamycin- and DMSO-injected males. Behaviors of spawning site entry increased in rapamycin-injected fish at 26 h post-injection than at 14 h post-injection significantly (P<0.05). Meanwhile, there was a tendency that GnRH1 neurons' soma size in the POA shrank by rapamycin injection, whereas the testes did not show notable changes. Taken together, these results suggest the possible role of TOR signal on GnRH1-mediated sexual behavior in cichlid dominant males, although further biological characterization of the TOR signaling pathway will be required to clarify this matter.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.4
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• pp.420-425
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• 2018

We characterized egg development and investigated the effects of temperature on embryonic development time, in the convict cichlid Amatitlania nigrofasciata. Fertilized eggs of this species have an ovoid shape (horizontal axis, $1.56{\pm}0.02mm$; vertical axis, $1.26{\pm}0.04mm$) and smooth translucent chorion surrounded by a layer of mucous secretion. At $27{\pm}0.5^{\circ}C$, the first cleavage, blastula, gastrula and 16-somite stages of A. nigrofasciata eggs began at 1.5, 4.83, 14 and 40 hours after fertilization, respectively. We measured the development rate of embryos at $12-33^{\circ}C$ and found that the time period from fertilization to hatching was 94 hours at $24^{\circ}C$, 64 hours at $27^{\circ}C$ and 50 hours at $30^{\circ}C$. At temperatures of $12-21^{\circ}C$, all fertilized eggs died before hatching and those incubated at $33^{\circ}C$ died immediately after hatching.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.3 no.2
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• pp.67-72
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• 2022

Ecological research relies on the interpretation of large amounts of visual data obtained from extensive wildlife surveys, but such large-scale image interpretation is costly and time-consuming. Using an artificial intelligence (AI) machine learning model, especially convolution neural networks (CNN), it is possible to streamline these manual tasks on image information and to protect wildlife and record and predict behavior. Ecological research using deep-learning-based object recognition technology includes various research purposes such as identifying, detecting, and identifying species of wild animals, and identification of the location of poachers in real-time. These advances in the application of AI technology can enable efficient management of endangered wildlife, animal detection in various environments, and real-time analysis of image information collected by unmanned aerial vehicles. Furthermore, the need for school education and social use on biodiversity and environmental issues using AI is raised. School education and citizen science related to ecological activities using AI technology can enhance environmental awareness, and strengthen more knowledge and problem-solving skills in science and research processes. Under these prospects, in this paper, we compare the results of our early 2013 study, which automatically identified African cichlid fish species using photographic data of them, with the results of reanalysis by CNN deep learning method. By using PyTorch and PyTorch Lightning frameworks, we achieve an accuracy of 82.54% and an F1-score of 0.77 with minimal programming and data preprocessing effort. This is a significant improvement over the previous our machine learning methods, which required heavy feature engineering costs and had 78% accuracy.

• Journal of Veterinary Clinics
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• v.27 no.2
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• pp.202-204
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• 2010

A flowerhorn fish with a subopercular mass, which had been reared in one of the private commercial aquaria was sent to the laboratory just before death. This fish began to show symptoms such as lethargy, anorexia, depression and dyspnea, and eventually died. The mass and intestinal organs were examined histopathologically. Thyroid showed variably sized follicles that contained abundant colloid and liver revealed steatosis. This report presents a case of goiter in the flowerhorn cichlid and its effect on the liver.

• Molecules and Cells
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• v.26 no.4
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• pp.387-395
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• 2008

A novel Tc1-like transposable element has been identified as a new DNA transposon in the mud loach, Misgurnus mizolepis. The M. mizolepis Tc1-like transposon (MMTS) is comprised of inverted terminal repeats and a single gene that codes Tc1-like transposase. The deduced amino acid sequence of the transposase-encoding region of MMTS transposon contains motifs including DDE motif, which was previously recognized in other Tc1-like transposons. However, putative MMTS transposase has only 34-37% identity with well-known Tc1, PPTN, and S elements at the amino acid level. In dot-hybridization analysis used to measure the copy numbers of the MMTS transposon in genomes of the mud loach, it was shown that the MMTS transposon is present at about $3.36{\times}10^4$ copies per $2{\times}10^9$ bp, and accounts for approximately 0.027% of the mud loach genome. Here, we also describe novel MMTS-like transposons from the genomes of carp-like fishes, flatfish species, and cichlid fishes, which bear conserved inverted repeats flanking an apparently intact transposase gene. Additionally, BLAST searches and phylogenetic analysis indicated that MMTS-like transposons evolved uniquely in fishes, and comprise a new subfamily of Tc1-like transposons, with only modest similarity to Drosophila melanogaster (foldback element FB4, HB2, HB1), Xenopus laevis, Xenopus tropicalis, and Anopheles gambiae (Frisky).

• Fisheries and Aquatic Sciences
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• v.26 no.9
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• pp.548-557
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• 2023

The purposes of this research were to identify fish species using DNA barcodes or partial sequences of cytochrome b (Cytb) and to assess the diversity of fish in the Mae Tam reservoir, Phayao province, Thailand. Fish samples were collected 3 times, during the winter, summer, and rainy seasons, from 2 sampling sites using gillnets with 3 mesh sizes (30, 50, and 70 mm). A total of 34 representative samples were classified into 12 species, 7 families and 6 orders by morphological- and DNA barcoding-based identifications. However, one cichlid species, Cichlasoma trimaculatum, could only be identified using DNA barcoding. Family Cyprinidae had the greatest diversity, 50.00%. The diversity, richness and evenness indices ranged from 0.43-0.65, 0.64-1.46, and 0.27-0.40, respectively, indicating that fish diversity at both sampling sites was relatively low. A comparison of the catch per unit effort (CPUE) with 3 different mesh sizes found that the 50 mm mesh size was the best (474.80 ± 171.56 g/100 m²/night), followed by the 70 mm (417.41 ± 176.24 g/100 m²/night) and 30 mm mesh sizes (327.88 ± 115.60 g/100 m²/night). These results indicate that DNA barcoding is a powerful tool for species identification. Our data can be used for planning the sustainable management of fisheries resources in the Mae Tam reservoir.