RESUMO
We examined factors related to dietary intake status (food form) of long-term care facility (LTCF) residents to identify factors related to proper food form choice for older individuals requiring nursing care. We surveyed 888 residents from 37 LTCFs in Japan. We evaluated basic information (age, sex, body mass index [BMI]), food form (swallowing-adjusted diet class), Barthel Index (BI), Clinical Dementia Rating (CDR), simply evaluated eating and swallowing functions, the number of present/functional teeth, oral diadochokinesis, repetitive saliva swallowing test (RSST), and modified water swallowing test. To clarify factors associated with food form, participants who had good nutrition by oral intake were categorized into the dysphagic diet (DD) and normal diet (ND) groups. Multi-level analyses were used to detect oral functions associated with food form status. Among objective assessments, BMI (odds ratio [OR] 0.979, 95% confidence interval [CI] - 0.022- to 0.006, p = 0.001), BI (OR 0.993, 95% CI - 0.007 to - 0.004, p < 0.001), CDR 3.0 (OR 1.002, 95% CI 0.002â0.236, p = 0.046), present teeth (OR 0.993, 95% CI - 0.007 to - 0.001, p = 0.011), functional teeth (OR 0.989, 95% CI - 0.011 to - 0.005, p < 0.001), and RSST (OR 0.960, 95% CI - 0.041 to - 0.007, p = 0.006) were significantly associated with DD vs ND discrimination. Simple evaluations of coughing (OR 1.056, 0.054â0.198, p = 0.001) and rinsing (OR 1.010, 0.010â0.174, p = 0.029) could also discriminate food form status. These simple evaluations provide insight into the discrepancies between food form status and eating abilities of LTCF residents. Periodic evaluations by the nursing caregiver may help to prevent aspiration by older individuals with dysphagia.
Assuntos
Transtornos de Deglutição , Seguro de Assistência de Longo Prazo , Humanos , Deglutição , Transtornos de Deglutição/diagnóstico , Estado Nutricional , Ingestão de Alimentos , Assistência de Longa DuraçãoRESUMO
BACKGROUND: Currently, patients with dysphagia are receiving dietary management that deviates from their original swallowing function. OBJECTIVE: To evaluate the clinical significance of fibreoptic endoscopic evaluation of swallowing (FEES) and dietary intervention (DI) by multi-professional collaboration during visit care for determining the actual oral intake status in patients with dysphagia. METHODS: Five hundred and eighteen patients with dysphagia underwent FEES, focusing on the penetration-aspiration scale, and DI. Oral intake status was categorised using the functional oral intake scale (FOIS). FOIS scores at the first visit, after FEES, and at the reassessment were compared. RESULTS: At the first visit, 34.7% of the patients had an FOIS score of level 1 (no oral intake) and 65.3% had a score of level 2 or higher (capable of oral intake). Following FEES, 7.1% of patients had an FOIS score of level 1, and 44.4% had a score of level 2 with resumption of oral intake. At the reassessment, 489 patients (94.4%) were capable of oral ingestion (FOIS level 2 or higher). There were significant differences between the distributions of FOIS scores at the first visit and following FEES (P < .01) and between those at the first visit and at the reassessment (P < .01). Regarding tube feeding, 17 (5.9%) of 289 patients, who had received tube feeding at the first visit, were completely capable of oral intake following FEES and at the reassessment. CONCLUSION: Appropriate evaluation of swallowing function using FEES and DI helps to understand the definite swallowing function in patients with dysphagia.
Assuntos
Transtornos de Deglutição , Deglutição , Idoso , Transtornos de Deglutição/diagnóstico , Assistência Odontológica , Nutrição Enteral , HumanosRESUMO
We studied the profiles of thyroid hormone receptors (TRs) in Japanese eels (Anguilla japonica) during development from hatched larvae to juveniles. Two TRαs (TRαA and TRαB) and one TRß (TRßA) cDNA clones were generated by RACE. The TRαA, TRαB and TRßA cDNAs encoded 416, 407 and 397 amino acid proteins with much higher homologies to the Japanese conger eel (Conger myriaster) TRs than to other fish TRs. In a transiently transfected Japanese eel cell line, Hepa-E1, the TRs showed thyroid hormone (TH)-dependent activation of transcription from the TH-responsive promoter. Four TR cDNA clones, including TRßB reported in a previous study, were analyzed by real-time RT-PCR. The TR mRNA levels in hatched larvae were determined. The two TRß mRNAs were present at low levels but there was a peak in the TRαs during the larval stage before metamorphosis. During metamorphosis, the two TRαs both exhibited peaks and expression of the two TRßs was higher than during the early growth stage. This expression pattern is similar to that of the Japanese conger eel. It is possible that thyroid hormones control the early development of Japanese eels and Japanese conger eels through TRs. This is the first analysis of the expression sequence of TRs during early larval stages of Anguilliformes.
Assuntos
Enguias/metabolismo , Receptores dos Hormônios Tireóideos/genética , Receptores dos Hormônios Tireóideos/metabolismo , Hormônios Tireóideos/genética , Animais , Enguias/genética , Larva/genética , Larva/metabolismo , Masculino , Metamorfose Biológica/genética , Metamorfose Biológica/fisiologia , Regiões Promotoras Genéticas/genéticaRESUMO
The viability of ornamental fish culture relies on the maintenance of high-quality breeds. To improve the profitability of culture operations we attempted to produce cloned fish from the somatic nucleus of the high-quality Japanese goldfish (Carassius auratus auratus) breed 'Ranchu'. We transplanted the nucleus of a cultured fin-cell from an adult Ranchu into the non-enucleated egg of the original goldfish breed 'Wakin'. Of the 2323 eggs we treated, 802 underwent cleavage, 321 reached the blastula stage, and 51 reached the gastrula stage. Two of the gastrulas developed until the hatching stage. A considerable number of nuclear transplants retained only the donor nucleus. Some of these had only a 2n nucleus derived from the same donor fish. Our results provide insights into the process of somatic cell nuclear transplantation in teleosts, and the cloning of Ranchu.
Assuntos
Núcleo Celular/metabolismo , Clonagem de Organismos/métodos , Engenharia Genética/métodos , Carpa Dourada/genética , Técnicas de Transferência Nuclear , Animais , Animais Geneticamente Modificados , Núcleo Celular/genética , Embrião não Mamífero/citologia , Embrião não Mamífero/embriologia , Embrião não Mamífero/metabolismo , Desenvolvimento Embrionário , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Carpa Dourada/embriologia , Carpa Dourada/metabolismo , Masculino , Óvulo/citologia , Óvulo/metabolismo , Poliploidia , Técnica de Amplificação ao Acaso de DNA PolimórficoRESUMO
In the present study, we examined methods for the cryopreservation of Epinephelus septemfasciatus spermatozoa. The percent motility, average path velocity, and linearity of movement (LIN) of fresh and corresponding post-thaw sperm were evaluated. Sperm motility was investigated using computer-assisted sperm analysis. Five percent dimethyl sulphoxide (Me2SO) with 95% fetal bovine serum (FBS) was the most successful cryoprotectant diluent with a comparative post-thaw motility of 77.6±8.5%; 5% dimethyl formamide was also effective. Fetal bovine serum was significantly better as an extender when compared with artificial seminal plasma, glucose, and trehalose solution. Sperm tolerated a wide range of cooling rates (from 27.1 to 94.3 °C min⻹); however, the post-thaw motility of sperm cooled to -30 °C was significantly lower than that of other cooled temperatures (-40 to -70 °C). The velocity of post-thaw sperm was significantly lower than that of fresh sperm, although LIN remained the same. For effective cryopreservation of seven-band grouper sperm, samples should be diluted in 5% Me2SO with 95% FBS and cooled to at least -40 °C before immersion in liquid nitrogen.
Assuntos
Criopreservação/veterinária , Preservação do Sêmen/veterinária , Animais , Aquicultura/métodos , Bass , Bovinos , Criopreservação/métodos , Dimetil Sulfóxido/farmacologia , Dimetilformamida/farmacologia , Sangue Fetal/fisiologia , Masculino , Preservação do Sêmen/métodos , Motilidade dos Espermatozoides , Espermatozoides/efeitos dos fármacosRESUMO
Major yolk protein (MYP), a transferrin superfamily protein contained in yolk granules of sea urchin eggs, also occurs in the coelomic fluid of male and female adult sea urchins regardless of their reproductive cycle. MYP in the coelomic fluid (CFMYP; 180 kDa) has a zinc-binding capacity and has a higher molecular mass than MYP in eggs (EGMYP; 170 kDa). CFMYP is thought to be synthesized in the digestive tract and secreted into the coelomic fluid where it is involved in the transport of zinc derived from food. To clarify when and where MYP synthesis starts, we investigated the expression of MYP during larval development and growth in Pseudocentrotus depressus. MYP mRNA was detected using RT-PCR in the early 8-arm pluteus stage and its expression persisted until after metamorphosis. Real-time RT-PCR revealed that MYP mRNA increased exponentially from the early 8-arm stage to metamorphosis. Western blotting showed that maternal EGMYP disappeared by the 4-arm stage and that newly synthesized CFMYP was present at and after the mid 8-arm stage. In the late 8-arm larvae, MYP mRNA was detected in the digestive tract using in situ hybridization, and the protein was found in the somatocoel and the blastocoel-derived space between the somatocoel and epidermis using immunohistochemistry. These results suggest that CFMYP is synthesized in the digestive tract and secreted into the body cavities at and after the early 8-arm stage. We assume that in larvae, CFMYP transports zinc derived from food via the body cavities to various tissues, as suggested for adults.
Assuntos
Proteínas do Ovo/biossíntese , Proteínas do Ovo/metabolismo , Trato Gastrointestinal/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Ouriços-do-Mar/metabolismo , Transferrina/metabolismo , Animais , Western Blotting , Imuno-Histoquímica , Hibridização In Situ , Larva/metabolismoRESUMO
The eels are teleost fishes from the order Anguilliformes that includes several species with high commercial value. Due to the high interest for aquaculture production of some eel species and for the need to restore eel species that are endangered, several research groups have directed their research toward developing protocols to cryopreserve the spermatozoa of Japanese eel (Anguilla japonica) and European eel (Anguilla anguilla). In this review, we provide an overview on the different protocols that have been developed so far. The first developed protocols used DMSO as cryoprotectant in both species with good success, obtaining sperm motilities of over 45% in Japanese eel and over 35% in European eel. Moreover, sperm cryopreserved using DMSO was successfully used in fertilization trials, although with low fertilization rates. However, recent studies show that DMSO produce epigenetic changes in eel sperm and therefore, the last developed protocols used methanol as cryoprotectant instead. Cryopreservation protocols using methanol as cryoprotectant, showed improved motility values in both Japanese and European eel. In addition, the latest protocols have been adapted to cryopreserve larger volumes of sperm of up to 5â¯mL, which is useful for larger scale fertilization trials. The present study introduces the state of the art and future perspectives of the eel sperm cryopreservation to be applied in aquaculture and biological conservation programs.
Assuntos
Anguilla/fisiologia , Preservação do Sêmen/veterinária , Espermatozoides/fisiologia , Animais , Criopreservação/métodos , Criopreservação/veterinária , Masculino , Preservação do Sêmen/métodos , VitrificaçãoRESUMO
We examined the relationship of several cardiovascular disease (CVD) risk factors to flow-mediated vasodilatation of the brachial artery (FMD) and the clustering effect of risk factors on FMD in Japanese subjects free of CVD. In 819 Japanese subjects free of CVD (age 45+/-10 years, 611 men and 208 women), FMD correlated significantly with the Framingham risk points score (FRS) (r=-0.27, p<0.01). FMD was higher in subjects in the 1st tertile of the FRS range than in patients in either the 2nd or 3rd tertiles of the FRS range, but it was similar between the subjects in the 2nd and 3rd tertiles. FMD was found to have a significant independent negative correlation with age (beta=-0.19, p<0.01), gender (beta=-0.024, p<0.01) and smoking habit (beta=-0.08, p=0.02). In subjects >or=50 years of age, the FMD in men with one CVD risk factor, excluding smoking, was similar to that in men with no CVD risk factors. CVD risk factors did not attenuate FMD in women. Thus, in Japanese subjects free of CVD, FMD may be a useful marker of CVD risk, but it may not be a robust marker for endothelial damage related to clusters of CVD risk factors. Age, gender and smoking were independent variables related to the impairment of FMD, which therefore appears to be less applicable in subjects aged 50 or more, and especially in women. (Hypertens Res 2008; 31: 2019-2025).
Assuntos
Artéria Braquial/fisiologia , Doenças Cardiovasculares/etiologia , Vasodilatação , Adulto , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fluxo Sanguíneo Regional , Fatores de RiscoRESUMO
Thyroid hormones (THs) are essential for the embryonic and post-embryonic development of fish. We studied the role of THs during the early, post-embryonic, development of Pacific bluefin tuna. Embryos were treated with L-thyroxine (T(4)) or the anti-thyroid drug methimazole (MMI), and reared in microtitre plates for 3 days. Immersion in MMI, but not T(4), led to retardation of retinal pigment epithelium (RPE) pigmentation 3 days post-hatching (dph). Concurrent immersion in T(4) and MMI had no effect of RPE pigmentation. We also measured the expression of TRalphaA, TRalphaB, and TRbeta mRNA using real-time RT-PCR. Treatment with MMI significantly reduced TRbeta mRNA expression. Taken together these results suggest that the development of RPE pigmentation is mediated by TH, most likely via TRbeta.
Assuntos
Olho/efeitos dos fármacos , Olho/metabolismo , Pigmentação/efeitos dos fármacos , Tiroxina/farmacologia , Atum/metabolismo , Animais , Cruzamento , Regulação da Expressão Gênica/efeitos dos fármacos , Metimazol/farmacologia , Epitélio Pigmentado Ocular/citologia , Epitélio Pigmentado Ocular/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores dos Hormônios Tireóideos/genética , Receptores dos Hormônios Tireóideos/metabolismo , Análise de Sobrevida , Atum/crescimento & desenvolvimentoRESUMO
Major yolk protein (MYP), a transferrin superfamily protein that forms yolk granules in sea urchin eggs, is also contained in the coelomic fluid and nutritive phagocytes of the gonad in both sexes. MYP in the coelomic fluid (CFMYP; 180 kDa) has a higher molecular mass than MYP in eggs (EGMYP; 170 kDa). Here we show that MYP has a zinc-binding capacity that is diminished concomitantly with its incorporation from the coelomic fluid into the gonad in the sea urchin Pseudocentrotus depressus. Most of the zinc in the coelomic fluid was bound to CFMYP, whereas zinc in eggs was scarcely bound to EGMYP. Both CFMYP and EGMYP were present in nutritive phagocytes, where CFMYP bound more zinc than EGMYP. Saturation binding assays revealed that CFMYP has more zinc-binding sites than EGMYP. Labeled CFMYP injected into the coelom was incorporated into ovarian and testicular nutritive phagocytes and vitellogenic oocytes, and the molecular mass of part of the incorporated CFMYP shifted to 170 kDa. Considering the fact that the digestive tract is a major production site of MYP, we propose that CFMYP transports zinc, essential for gametogenesis, from the digestive tract to the ovary and testis through the coelomic fluid, after which part of the CFMYP is processed to EGMYP with loss of zinc-binding site(s).
Assuntos
Proteínas do Ovo/metabolismo , Proteínas do Ovo/fisiologia , Gametogênese/fisiologia , Zinco/metabolismo , Animais , Western Blotting , Cromatografia em Gel , Proteínas do Ovo/isolamento & purificação , Eletroforese em Gel de Poliacrilamida , Ligação Proteica , Transporte Proteico , Ouriços-do-MarRESUMO
Two heterotrinuclear complexes, [Mn(II)(Ni(II)L)2].2CH3OH (where H3L = 1,1,1-tris(N-salicylideneaminomethyl)ethane) and [Fe(III)(Ni(II)L)2]NO3.C2H5OH, consisting of three face-sharing octahedra have been prepared; although these complexes have closely related structures and have the same 1-5/2-1 spin system, they show completely different magnetic interactions between the adjacent metal ions: ferromagnetic (Ni(II)-Mn(II)) and antiferromagnetic (Ni(II)-Fe(III)).
RESUMO
A cDNA encoding transthyretin was cloned from the Pacific bluefin tuna (Thunnus orientalis). This cDNA contains a complete open reading frame encoding 151 amino acid residues. The deduced amino acid sequence is 81% and 55% identical to the gilthead seabream and common carp forms, respectively, and 33-39% to mammalian, reptilian, and amphibian forms. A 1.0-kb transcript was found in the the liver and ovary; the liver is the main source of this protein. Analysis of triiodo-L-thyronine (T(3)) and L-thyroxine (T(4)) binding demonstrated that both T(3) and T(4) bind to bluefin transthyretin. The binding activity of T(3) for bluefin transthyretin is higher than that of T(4). These results indicate that bluefin transthyretin acts as a transporter of thyroid hormones (THs) in the plasma, and plays an important role in the function of THs in target cells.
Assuntos
DNA Complementar/análise , Fígado/metabolismo , Pré-Albumina/genética , Pré-Albumina/isolamento & purificação , Hormônios Tireóideos/metabolismo , Atum/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , DNA Complementar/química , Feminino , Expressão Gênica , Masculino , Dados de Sequência Molecular , Fases de Leitura Aberta , Ovário/metabolismo , Pré-Albumina/química , RNA Mensageiro/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Alinhamento de Sequência , Homologia de Sequência do Ácido Nucleico , Tiroxina/metabolismo , Tri-Iodotironina/metabolismo , Atum/sangueRESUMO
In a previous study, we identified cDNAs encoding the growth hormone receptor (eGHR1) and eGHR1 homologue (eGHR2) in Japanese eel (Anguilla japonica). In the present study, changes in the developmental expression of growth hormone (GH), eGHR1 and eGHR2 were investigated in the Japanese eel eggs and preleptocephali by RT-PCR and immunohistochemical methods in an attempt to examine the involvement of these proteins in larval growth. The GH transcripts and the production of GH protein were not detected in the newly hatched larvae and preleptocephali at day 3 post-hatch, however, these were detected at day 6 post-hatch, and also detected at higher levels at day 10 post-hatch. In contrast, prolactin and somatolactin transcripts could not be detected in all preleptocephalus specimens (newly hatched larvae and preleptocephali at day 3, 6 and 10 post-hatch). eGHR1 and eGHR2 transcripts were detected in all preleptocephalus specimens. Therefore, it is plausible that the actions of GH during the preleptocephalus stage are mediated through the eGHRs. The present data suggest that GHR-mediated actions of GH begin at the same time as the initiation of GH production, and that GH plays important roles in larval growth and survival to the leptocephalus stage. eGHR1 mRNA, which is thought to be of maternal origin, was also detected in ovulated eggs. However, the role of eGHR1 mRNA in eggs is not clear.
Assuntos
Anguilla/crescimento & desenvolvimento , Anguilla/metabolismo , Hormônio do Crescimento/metabolismo , Receptores da Somatotropina/metabolismo , Animais , Feminino , Regulação da Expressão Gênica , Imuno-Histoquímica , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismoRESUMO
We previously isolated cDNAs encoding conger eel (Conger myriaster) thyroid hormone (TH) receptors (TRs). In the present study, we investigated the transactivation activities of conger eel TRs treated with THs (3,3',5-triiodo-l-thyronine [T3], l-thyroxine [T4], and 3,3',5'-triiodo-l-thyronine [rT3]), or ligands and activators of other nuclear receptors. Following transient transfection into the Japanese eel (Anguilla japonica) hepatocyte cell line Hepa-E1, the conger eel TRs (cTRs) showed TH-dependent activation of transcription from a TH-responsive promoter. However, no transactivation activity of any of the four cTRs was observed with ligands or activators of other nuclear receptors. Although T3 activation for cTRs is stronger than other THs (T3>T4>rT3), the transactivation sensitivity was different from the activity of cTRs with THs, respectively. Therefore, we conclude that cTRs can act in concert with THs in fish metamorphosis.
Assuntos
Enguias/metabolismo , Receptores dos Hormônios Tireóideos/metabolismo , Hormônios Tireóideos/farmacologia , Ativação Transcricional , Animais , Linhagem Celular , Hepatócitos/citologia , Hepatócitos/metabolismo , Fígado/metabolismo , Receptores dos Hormônios Tireóideos/agonistas , Receptores dos Hormônios Tireóideos/genética , Tiroxina/farmacologia , Tri-Iodotironina Reversa/farmacologiaRESUMO
The eel has long been esteemed as an important food fish in the world, especially in Japan, and has been used as an experimental fish for many fields of fish physiology. However, the decreases in eel resources have been a serious concern in recent years. The catches of glass eels as seedlings for aquaculture have shown a long-term decrease in both Europe and East Asia. To increase eel resources, the development of techniques for artificial induction of maturation and spawning and rearing their larvae have been eagerly desired. Recent progress of reproductive physiology of fish, especially mechanisms of oocyte maturation and ovulation in female and of spermatozoa maturation in male, facilitate to establish techniques for hormonal induction of maturation and spawning in sexually immature eels. With persistent effort to development of rearing techniques of larvae, we have first succeeded to produce glass eel. These applied techniques are may contribute to understand the basic reproductive physiology of the eel.
RESUMO
Sea urchins of both sexes store the nutrients necessary for gametogenesis in nutritive phagocytes of the agametogenic gonad. A zinc-binding protein termed the major yolk protein (MYP) is stored here as two isoforms: the egg-type (predominant in egg yolk granules) and the coelomic fluid-type (a precursor with greater zinc-binding capacity). MYP is used during gametogenesis as material for synthesizing gametic proteins and other components. We investigated its accumulation and relationship to zinc contents in gonads during the non-reproductive season in Pseudocentrotus depressus. MYP constituted most of the protein in coelomic fluid and gonads. Both ovaries and testes grew gradually, accumulating MYP and zinc during the year. Total zinc contents and the ratio of coelomic fluid-type to egg-type protein were higher in ovaries than in testes as gametogenesis approached. Most of the zinc in the coelomic fluid was bound to MYP, and the concentrations of MYP and zinc were elevated toward the onset of oogenesis in the female coelomic fluid. Thus, MYP accumulates in the agametogenic ovaries and testes during the non-reproductive season, playing a role as a carrier to transport zinc to the gonad. Transportation of zinc by MYP is more active in females than in males.
Assuntos
Proteínas do Ovo/metabolismo , Fagócitos/metabolismo , Ouriços-do-Mar/fisiologia , Zinco/metabolismo , Animais , Feminino , Gônadas/metabolismo , Masculino , Ligação Proteica , Ouriços-do-Mar/metabolismoRESUMO
Species and sex identification are among the most important parameters for conservation management. However, it is extremely difficult to perform such identification in Formosa landlocked salmon (Oncorhynchus masou formosanus). Both sexual dimorphism in landlocked dwarf form Formosa landlocked salmon and morphological difference among cherry salmon complex are minimal. We developed a simple, rapid and noninvasive method for identifying sex and species of this critically endangered species using a loop-mediated isothermal amplification (LAMP) technique. The LAMP assay showed the advantage of simple detection (evaluated by visual inspection), rapid reaction time (< 1 h), isothermal condition (less equipment required) and high efficiency (only 0.5-5 pg of DNA was required in the reaction mixture). Therefore, the method is more economical and practical than PCR. The LAMP assay can be easily performed in the field and is a valuable tool for detecting sex ratios in wild populations and identifying species in commercial imports. This is the first application of LAMP in identifying species and sex of salmonids as far as we know and clearly shows the potential application of LAMP in molecular ecology and conservation efforts.
Assuntos
Conservação dos Recursos Naturais/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Oncorhynchus/genética , Animais , Primers do DNA/genética , Eletroforese em Gel de Ágar , Sensibilidade e Especificidade , Análise para Determinação do Sexo , Especificidade da Espécie , TaiwanRESUMO
Hyaluronan (HA) is a linear polysaccharide of high molecular weight that exists as a component of the extracellular matrix. The larvae (leptocephali) of the Japanese conger eel (Anguilliformes: Conger myriaster) have high levels of hyaluronan (HA) which is thought to help control body water content. We isolated glycosaminoglycans (GAGs) from Japanese conger eel leptocephali and measured the changes in tissue HA content during metamorphosis. HA content decreased during metamorphosis. In contrast, neutral sugar content increased during metamorphosis. We hypothesize that the leptocephali utilize a metabolic pathway that converts HA to glucose during metamorphosis. Glucose may then be metabolized to glycogen and stored in the juvenile life-history stage.
RESUMO
We studied the profiles of 3,5,3'-l-triiodothyronine (T3), thyroxine (T4), and thyroid hormone receptors (TRs) in Pacific bluefin tuna (Thunnus orientalis) during embryonic and post-embryonic development. Both T3 and T4 were detected in embryos just before hatching, and it was found that the levels of both were increased in postflexion fish. The thyroid follicles were increased in both size and number in postflexion fish compared with preflexion fish. A TRbeta cDNA clone was generated by RACE. Two TRalpha cDNA clones were also partially identified and analyzed by real-time RT-PCR in this study. The TR mRNA levels in embryos were determined, and these were found to be lower than those in preflexion fish. Therefore, we considered that thyroid hormones function during early post-embryonic development as well as during embryonic development. Moreover, there was a peak in the TR mRNA level during postflexion stages, as seen during metamorphosis in Japanese flounder and Japanese conger eel. It is possible that thyroid hormones control the early development of scombrid fish through TRs, as they do for Pluronectiformes and Anguilliformes.