Search PubMed⌕ Search

Biomedical subjects

M Higa

Publications and source records attributed to M Higa.

At least 19 recordsLinked to original sources
PubMed2006

Protein kinase B/Akt signalling is required for palmitate-induced beta-cell lipotoxicity.

AIM: This study was conducted to clarify cell death and survival signals in pancreatic beta-cell lipotoxicity. METHODS: Rat insulinoma INS-1 cells, with or without expression of dominant-negative mutant of Akt (K179M), were cultured with palmitate (C16:0) or oleate (C18:1) and cell numbers were determined by 0.2% eosin dye exclusion assay. The Akt activity was determined by anti-3'-phospho-inositide-dependent protein kinase (Akt)/protein kinase B (PKB) or anti-phospho-Akt (Serine 473) immunoblotting, and nuclear protein nuclear factor-kB (NF-kappaB)-binding activity was by supershift analysis. RESULTS: Twenty-four hours treatment with palmitate increased the INS-1 cell number at 0.1-0.2 mM but decreased the cell number at 0.5-1 mM. Oleate did not affect cell number at 0.1-1.0 mM. Palmitate dose-dependently increased phosphorylation of 473th serine in Akt/PKB. The K179M form of Akt/PKB abolished palmitate-induced cell proliferation at the low dose and death at the high dose. Nuclear protein NF-kappaB binding was enhanced at 0.2 and 0.5 mM of palmitate but decreased at 1.0 mM. CONCLUSION: Results suggest that Akt/PKB signalling is involved in palmitate-induced cell death and survival of pancreatic beta cell.

Animals↗
PubMed2005

Three-dimensional computer-aided design based design sensitivity analysis and shape optimization of the stem using adaptive p-method.

The number of stem designs for total hip arthroplasty is increasing, and occasionally design changes have yielded unexpected clinical results. At present, we are not able to clearly identify which parameter of the stem is most important, and the optimum value of many parameters. The goals of this study were to identify which parameter is most important, to understand the effect of design change, and to find the optimum stem shape. For this purpose, we used adaptive p-method together with three-dimensional computer-aided design software program for the design sensitivity analysis (DSA) and shape optimization of the stem. The results suggested that increasing the lateral and medial width of the distal cross-section together with decreasing the medial-lateral width and the medial radius of the distal cross-section from the default value would lead to a decrease in the largest maximum principal stress of the distal cement. The medial width of middle cross-section, however, was not so simple. The result of DSA suggested that decreasing this parameter from the default value decreased the stress in the distal cement, but the optimum shape was obtained by increasing this parameter. The method used in this study will assist our engineers and surgeons in the process of modifying and optimizing the stem design.

Arthroplasty, Replacement, Hip↗
PubMed2002

Epstein-Barr virus (EBV) subtype in EBV related oral squamous cell carcinoma in Okinawa, a subtropical island in southern Japan, compared with Kitakyushu and Kumamoto in mainland Japan.

AIM: In Okinawa, a subtropical island located between the East China Sea and Pacific Ocean, 2000 km south of mainland Japan, the incidence of oral squamous cell carcinoma is 1.5 times higher than that seen in mainland Japan, and a large number of these patients have been reported to be infected with the Epstein-Barr virus (EBV). This study aimed to gain a better understanding of the pathogenesis of this malignancy in this area by carrying out genomic analysis of EBV. METHODS: Fifty four patients with oral squamous cell carcinoma reported from 1997 to 1999 in Okinawa were compared with 21 and 20 patients from Kitakyushu and Kumamoto in Kyushu, mainland Japan, respectively. Diagnosis was confirmed by conventional histological examination of paraffin wax sections. EBV was detected by non-isotopic in situ hybridisation (NISH) and the polymerase chain reaction (PCR) (Bam HI-F, EBV nuclear antigen 2 (EBNA2), and latent membrane protein 1 (LMP-1) regions). Sequence analysis of the PCR products was also carried out. RESULTS: In Okinawa, 25 patients were found to be infected with EBV type A by analysing the 3' sequence divergence of the EBNA2 genes. Six patients were positive for EBV type B, and eight for both type A and B. Therefore, type A virus infection was demonstrated in 33 of 54 patients, and type B in 14 of 54. In total, 39 of 54 patients were infected with EBV. However, the "f" variant was shown in only one patient, who was also infected with type A virus. In contrast, 97.0% of EBV type A infected patients showed a 30 bp deletion of the LMP-1 gene, but those infected with EBV type B did not. Sequence analysis of the type A virus EBNA2 gene revealed slight variations of the sequence (mutations)-(48991)G-->T and (48998)C-->A-in 18 of 33 cases compared with the B95-8 strain, and in 14 cases, in addition to these, a further mutation of (48917)T-->C was demonstrated; in the single remaining case, only one mutation at (49137)A-->G was detected. The mutations at 48991 (G-->T), and 49137 (A-->G) are associated with amino acid changes Arg-->Met and Thr-->Ala, respectively. In contrast, no mutation was seen in the EBNA2 DNA from the 14 cases of type B virus when compared with that of the Jijoye strain. In Kitakyushu and Kumamoto, only 10 of 41 patients (six in Kitakyushu and four in Kumamoto) were infected with EBV. Among them, nine patients were infected with type A virus, and only one patient from Kitakyushu was infected with type B virus. The (48991)G-->T and (48998)C-->A mutations of the EBNA2 region were demonstrated in type A virus, but the (48917)T-->C and (49137)A-->G mutations were not when compared with the B95-8 strain. In the case of type B virus no mutation was noted. A 30 bp deletion was found in these nine cases of type A, but not in type B. The sequence analysis of EBV type A in Okinawa, Kitakyushu, and Kumamoto showed slight variations when compared with B95-8, but EBV type B LMP-1 did not when compared with the Jijoye strains. CONCLUSION: In Okinawa, EBV infection was frequently demonstrated in oral squamous cell carcinoma (p < 0.001). However, in mainland Japan there was no significant correlation between EBV and oral squamous cell carcinoma. In Okinawa, EBV type B infection is approximately 10 times more common than in the mainland. However, in these areas-Okinawa, Kitakyushu, and Kumamoto-the frequency of the "f " variant was very low, whereas a high incidence of a 30 bp deletion of LMP-1 was noted. The number of EBV (including type A and/or B) infected oral squamous cell carcinomas in Okinawa was about three times higher than that seen in the mainland, although the frequency of oral squamous carcinoma was only 1.5 times higher than that seen in the mainland. A high prevalence of type B virus infection and slight differences in the EBNA2 gene sequence in the type A virus might influence the frequency of this carcinoma in Okinawa.

Adult↗
PubMed2001

Expression of Fushi tarazu factor 1 homolog and Pit-1 genes in the pituitaries of pre-spawning chum and sockeye salmon.

Fushi tarazu factor-1 (FTZ-F1) and Pit-1 are major pituitary transcription factors, controlling expression of genes coding for gonadotropin (GTH) subunits and growth hormone/prolactin/somatolactin family hormone, respectively. As a first step to investigate physiological factors regulating gene expression of these transcription factors, we determined their mRNA levels in the pituitaries of chum salmon (Oncorhynchus keta) at different stages of sexual maturation. FTZ-F1 gene expression was increased in males at the stage before spermiation, where the levels of GTH alpha and IIbeta subunit mRNAs were elevated. Pit-1 mRNA showed maximum levels at the final stage of sexual maturation in both sexes, when expression of somatolactin gene peaked. To clarify whether gonadotropin-releasing hormone (GnRH) is involved in these increases in FTZ-F1 and Pit-1 gene expression, we examined effects of GnRH analog (GnRHa) administration on their gene expression in maturing sockeye salmon (Oncorhynchus nerka). GnRHa stimulated Pit-1 gene expression in females only, but failed to stimulate FTZ-F1 gene expression in both sexes. The up-regulated expression of FTZ-F1 and Pit-1 genes at the pre-spawning stages suggest that the two transcription factors have roles in sexual maturation of salmonids. Physiological factors regulating gene expression of FTZ-F1 and Pit-1 are discussed in this review.

Animals↗
PubMed2001

Extremely high Langerhans cell infiltration contributes to the favourable prognosis of HPV-infected squamous cell carcinoma and adenocarcinoma of the lung.

AIMS: The infiltration of Langerhans cells in adenocarcinomas and squamous cell carcinomas of the lung was examined in relation to prognostic implications and human papillomavirus (HPV) infection. METHODS AND RESULTS: Samples from 62 adenocarcinoma and 59 squamous cell carcinoma patients in 1995-97, the prognosis of which had been followed up, were used. The Langerhans cells were demonstrated immunohistochemically using anti S100a and CD1 antibodies. Human papillomavirus (HPV) infection was examined by polymerase chain reaction (PCR) and nonisotopic in-situ hybridization (NISH) methods. Statistical analysis was carried out using the Kaplan-Meier method (Wilcoxon analysis) and multiple regression analysis. HPV infection was demonstrated in 12 cases (19.4%) of adenocarcinoma. The HPV-infected adenocarcinomas had abundant faintly eosinophilic cytoplasm, and were immunohistochemically positive for the surfactant apoprotein A. In the 59 cases of squamous cell carcinomas 19 were of the well differentiated form, and 29 and 11 were moderately and poorly differentiated cases, respectively. HPV was detected in 29 cases (49.2%) (13 well and 16 moderately differentiated cases). In all HPV-infected adenocarcinoma and squamous cell carcinoma cases, extremely large numbers of Langerhans cells (more than 100 per high-power field) were demonstrated in the tumour nests. In contrast, in the non-HPV-infected adenocarcinomas and squamous cell carcinomas, only a few (less than about 10 per high-power field) Langerhans cells were observed. The squamous cell carcinoma cases with high Langerhans cell infiltration, which were also infected with HPV, showed a significantly good prognosis (P = 0.007). The adenocarcinoma cases with high Langerhans cell infiltration tended to have a better prognosis than the cases with low Langerhans cell infiltration, but the difference was not statistically significant. The low number of highly infiltrated cases was insufficient for an adequate statistical analysis. Furthermore, there was no significant correlation between either Langerhans cell infiltration and smoking, or HPV infection and smoking, in either squamous cell carcinoma or adenocarcinoma cases. CONCLUSIONS: It was considered that the extremely high Langerhans cell infiltration in the tumours was caused by HPV infection. The extremely large number of Langerhans cells in the tumours contributes to the favourable prognosis for HPV-infected lung cancer.

Adenocarcinoma↗
PubMed2001

Differences in EBNA2 and LMP-1 carboxy terminal region sequences of Epstein-Barr virus type A between the tumors in a multiple cancer patient.

Using PCR, type A Epstein-Barr virus (EBV) infection was demonstrated in a squamous cell carcinoma of the maxilla (in a 52-year-old man) and the tongue of the same patient 18 years later (at the age of 70). Furthermore, at the age of 72, this patient developed an EBV-infected anaplastic large cell lymphoma. Analysis of the terminal regions of the EBV genome revealed a monoclonal proliferation of EBV-infected lymphoma cells. However, sequence analysis of the EBV revealed a slight difference in the EBNA2 regions between the virus-infected lymphoma and the squamous cell carcinomas. The mutations at 48991 (G-->T) and 48998 (C-->A) were demonstrated in the lymphoma. Although the squamous cell carcinoma of the tongue occurred after an interval of 18 years, the mutation site in the carcinomas was the same, 49137 (A-->G), as compared with B95-8 strain EBV EBNA2. The mutations at 48991 and at 49137 were associated with amino acid changes, Arg-->Met and Thr-->Ala, respectively, but the alteration at 48998 was a silent mutation. Thirty-bp deletion in the LMP-1 carboxy terminal region was demonstrated in the virus-infected lymphoma, but not in the squamous cell carcinomas. On the other hand, HTLV-1 proviral DNA (tax, gag and env) was not detected in the lymphoma, nor was HPV demonstrated in the squamous cell carcinomas, although Okinawa is known as an HTLV-1 and HPV prevalence region. The T-cell receptor beta gene rearrangement was demonstrated in the lymphoma, but the t(2;5) fusion transcript was not detected using PCR. Cytogenetic analysis of the lymphoma cells showed a complex hypertriploid karyotype with 76XY. The type A EBV infection might play a role in the carcinogenesis of the tumors of our patient. Interestingly, the infected virus genome sequences, the EBNA2 and LMP-1 regions, which were closely associated with carcinogenesis in the squamous cell carcinomas and the lymphoma, showed slight differences.

Aged↗
PubMed2001

Portal and mesenteric vein and inferior vena cava thrombosis associated with antiphospholipid syndrome.

We report a 48-year-old man with thrombosis of the portal and superior mesenteric vein and inferior vena cava associated with primary antiphospholipid syndrome (APS). Primary APS was diagnosed by a positive reaction with anticardiolipin antibody (aCL) and the absence of any evidence suggesting the presence of other disease states known to be associated with aCL. A coeliac angiography showed obstruction of the portal and superior mesenteric vein with prominent collaterals and cavernous transformation. Femoral vein angiography showed total obstruction of the external iliac vein and inferior vena cava, and dilation of the pelvic veins, with contrast medium in the lumbar vein. This case is noteworthy as a report of primary APS accompanied by extensive abdominal and pelvic venous thrombosis.

Antiphospholipid Syndrome↗
PubMed2001

An outbreak of allergy-like food poisoning.

Eight cases of allergy-like food poisoning resulting from the ingestion of yellowfin tuna, which had been kept in stock for 10 days prior to being cooked, are described. The main symptoms were headaches, facial flushing and palpitation. Samples of the ingested fish were analyzed for histamine content, and a high level of histamine was confirmed (310 mg/100 g of fish). Corticosteroids were given to 3 patients who exhibited dyspnea or persistent symptoms, while the remaining patients improved without medication. In situations where allergy-like clinical features are present after the ingestion of food, the possibility of allergy-like food poisoning should be recognized and included in a differential diagnosis.

Adult↗
PubMed2001

[A case of acute pulmonary embolism associated with squatting].

The patient was a 69-year-old man with a 3-year history of diabetes mellitus accompanied by cerebral infarction and arteriosclerosis obliterans of the lower extremities. After squatting to clean a car, the patient began to experience dyspnea. A blood gas analysis was performed upon admission, and the patient's PaCO2 and PaO2 levels were found to be low. Examination of a blood sample revealed elevated FDP, FDP-D dimer and platelet factor 4 levels. A perfusion lung scan showed multiple defects in both lungs, but no abnormal findings were detected on a ventilation scan. A pulmonary angiogram showed an interrupted blood flow in branches A9 + 10 of the left pulmonary artery. Accordingly, a pulmonary embolism was diagnosed. Squatting may have caused a partial obstruction of the venous return from the lower extremities by compression of the inguinal region and may have been a predisposing cause of the thrombosis. To our knowledge, such cases of pulmonary embolism triggered by the act of squatting are very rare.

Acute Disease↗
PubMed2001

[Aeromonas species infection with severe clinical manifestation in okinawa, Japan -association with gas gangrene-].

We experienced two patients having Aeromonas species infection with severe clinical manifestations. The one patient was a 15-year-old high school girl student, who had been healthy in her school life, was admitted to the hospital with a sudden onset of left thigh muscle pain and swelling. She subsequently went into septic shock and died one day after admission. Pathological examination on autopsy revealed massive gas formation, skin bullas and ulcers, and extensive severe soft tissue damage throughout the body. Also, all the specimens, including brain, liver, spleen, thigh muscle, and blood in cardiac cavity, were positive for A. veronii biovar sobria. The other patient was 35-year-old man, who suffered from multiple bone fractures during the work in the harbor. One day after admission, he became febrile and went into septic shock. With the presumptive diagnosis of sepsis and gas gangrene, amputation of left thigh was performed. The exudate and aspirate of the amputated portion were repeatedly positive for A. hydrophila. Through the surveillance in Okinawa, Kagoshima, Miyazaki, and Kumamoto Prefectures, a total of 426 isolates from blood cultures were collected in the period from August, 1999 to February, 2000. Of these, 14 isolates (3.3%) were the species of Aeromonas. Of 14 isolates of Aeromonas, 13 were reported from Okinawa and the remaining one was from Kumamoto. Most patients had underlying diseases, particularly liver diseases including liver cirrhosis. The mortality rate was extremely high at 62.5%, and the patients died in short terms after blood culture became positive. With these, Aeromonas species infection is unique to Okinawa, and positive blood culture for Aeromonas species potentially indicates a high-risk, particularly among the patients with underlying diseases.

Adolescent↗
PubMed2000

Slow recovery of body fat lost during adenovirus-induced hyperleptinemia.

In normal rats, adenovirus-induced hyperleptinemia causes disappearance of visible body fat, downregulation of lipogenic enzymes, and upregulation of oxidative enzymes and thermogenic proteins. In addition, preadipocyte markers replace mature adipocyte markers, suggesting dedifferentiation. In weight loss induced by caloric restriction, by contrast, the lipogenic machinery is essentially intact. To determine if the radical changes induced by leptin would slow the reappearance of body fat, we compared normal lean rats made hyperleptinemic by infusing an adenovirus-leptin construct with diet-matched littermates. Initially, in plasma leptin the hyperleptinemic rats averaged approximately 50x the controls and, although it declined progressively, it was still slightly elevated at 150 days (P < 0.05). In the hyperleptinemics, body fat mass, quantified by magnetic resonance spectroscopy, remained below the pretreatment value for 60 days, while in diet-matched controls it exceeded the pretreatment value. Epididymal fat pad weight in hyperleptinemics was still 28% below paired controls at 150 days posttreatment. Histologic examination revealed adipocytes of hyperleptinemic animals to be smaller 60 days after treatment. At 60 days, adipose tissue UCP-2 gene expression in hyperleptinemics was still above controls, but expression of other lipogenic and oxidative enzymes had returned to baseline expression levels. We conclude that in normal rats recovery of body fat following adenovirus-induced hyperleptinemia is much slower than after caloric restriction, possibly because of persistent upregulation of adipocyte UCP-2.

Adenoviridae↗
PubMed2000

Liporegulation in diet-induced obesity. The antisteatotic role of hyperleptinemia.

To test the hypothesis that the physiologic liporegulatory role of hyperleptinemia is to prevent steatosis during caloric excess, we induced obesity by feeding normal Harlan Sprague-Dawley rats a 60% fat diet. Hyperleptinemia began within 24 h and increased progressively to 26 ng/ml after 10 weeks, correlating with an approximately 150-fold increase in body fat (r = 0.91, p < 0.0001). During this time, the triacylglycerol (TG) content of nonadipose tissues rose only 1-2.7-fold implying antisteatotic activity. In rodents without leptin action (fa/fa rats and ob/ob and db/db mice) receiving a 6% fat diet, nonadipose tissue TG was 4-100 times normal. In normal rats on a 60% fat diet, peroxisome proliferator-activated receptor alpha protein and liver-carnitine palmitoyltransferase-1 (l-CPT-1) mRNA increased in liver. In their pancreatic islets, fatty-acid oxidation increased 30% without detectable increase in the expression of peroxisome proliferator-activated receptor-alpha or oxidative enzymes, whereas lipogenesis from [14C]glucose was slightly below that of the 4% fat-fed rats (p < 0.05). Tissue-specific overexpression of wild-type leptin receptors in the livers of fa/fa rats, in which marked steatosis is uniformly present, reduced TG accumulation in liver but nowhere else. We conclude that a physiologic role of the hyperleptinemia of caloric excess is to protect nonadipocytes from steatosis and lipotoxicity by preventing the up-regulation of lipogenesis and increasing fatty-acid oxidation.

Animals↗
PubMed2000

Leptin, troglitazone, and the expression of sterol regulatory element binding proteins in liver and pancreatic islets.

Overaccumulation of lipids in nonadipose tissues of obese rodents may lead to lipotoxic complications such as diabetes. To assess the pathogenic role of the lipogenic transcription factor, sterol regulatory element binding protein 1 (SREBP-1), we measured its mRNA in liver and islets of obese, leptin-unresponsive fa/fa Zucker diabetic fatty rats. Hepatic SREBP-1 mRNA was 2.4 times higher than in lean +/+ controls, primarily because of increased SREBP-1c expression. mRNA of lipogenic enzymes ranged from 2.4- to 4.6-fold higher than lean controls, and triacylglycerol (TG) content was 5.4 times higher. In pancreatic islets of fa/fa rats, SREBP-1c was 3.4 times higher than in lean +/+ Zucker diabetic fatty rats. The increase of SREBP-1 in liver and islets of untreated fa/fa rats was blocked by 6 weeks of troglitazone therapy, and the diabetic phenotype was prevented. Up-regulation of SREBP-1 also occurred in livers of Sprague-Dawley rats with diet-induced obesity. Hyperleptinemia, induced in lean +/+ rats by adenovirus gene transfer, lowered hepatic SREBP-1c by 74% and the lipogenic enzymes from 35 to 59%. In conclusion, overnutrition increases and adenovirus-induced hyperleptinemia decreases SREBP-1c expression in liver and islets. SREBP-1 overexpression, which is prevented by troglitazone, may play a role in the ectopic lipogenesis and lipotoxicity complicating obesity in Zucker diabetic fatty rats.

Adenoviridae↗
PubMed2000

Lipotoxic heart disease in obese rats: implications for human obesity.

To determine the mechanism of the cardiac dilatation and reduced contractility of obese Zucker Diabetic Fatty rats, myocardial triacylglycerol (TG) was assayed chemically and morphologically. TG was high because of underexpression of fatty acid oxidative enzymes and their transcription factor, peroxisome proliferator-activated receptor-alpha. Levels of ceramide, a mediator of apoptosis, were 2-3 times those of controls and inducible nitric oxide synthase levels were 4 times greater than normal. Myocardial DNA laddering, an index of apoptosis, reached 20 times the normal level. Troglitazone therapy lowered myocardial TG and ceramide and completely prevented DNA laddering and loss of cardiac function. In this paper, we conclude that cardiac dysfunction in obesity is caused by lipoapoptosis and is prevented by reducing cardiac lipids.

Age Factors↗
PubMed2000

Experimental myelitis in BALB/cN and C57BL/6N mice caused by herpes simplex virus type 1 compared with herpes simplex virus type 2.

Intraperitoneal and footpad inoculations of herpes simplex virus type 1 (HSV) into BALB/cN (HSV-susceptible) and C57BL/6N (HSV-resistant) mice were carried out to induce experimental myelitis. Standard laboratory strains (McIntyre, F, RK, and recently Okinawa strain R1) were inoculated in mice. As a control, the HSV 2 standard laboratory strain SAV was also inoculated. The McIntyre strain was the most virulent, while the F strain was the least. RK and R1 were both moderately virulent. Myelitis was induced in BALB/cN mice after intraperitoneal and footpad inoculations of low to high doses of the McIntyre strain, and intraperitoneal inoculation of moderate and high doses of the RK and R1 strains. Symptoms of paraplegia of the hind legs and rectal and urinary incontinence were observed, but not until 3-5 hours before death. The symptoms caused by footpad inoculation were slightly different from those following intraperitoneal inoculation; rectal incontinence, in particular, was inconspicuous in the former. In the case of footpad inoculation of RK and R1, only one mouse inoculated with R1 showed symptoms and histology of myelitis. The F strain caused no symptoms. In the case of C57BL/6N mice, high dose intraperitoneal and footpad inoculations of the McIntyre strain also caused myelitis, and the symptoms were observed about 6-7 hours before death. In only one C57BL/6N mouse intraperitoneally inoculated with a high dose of R1 did symptoms appear about 6 hours before death. The same symptoms caused by intraperitoneal and footpad inoculations of HSV 2 (SAV) were observed more clearly and for a longer period (half to one day) than those caused by HSV 1 inoculation. Spinal cord necrosis was noted with McIntyre, RK and R1 inoculations, but it was not marked with randomly located foci, when compared with that caused by SAV. Further, the foci of necrosis in C57BL/6N mice were smaller than in BALB/cN mice, even when high dose McIntyre strain was used. Nuclear pyknosis and edema of the brain in the dead mice following HSV 1 inoculation were more marked than in those killed by SAV.

Animals↗
PubMed2000

Quantitative analysis of fushi tarazu factor 1 homolog messenger ribonucleic acids in the pituitary of salmon at different prespawning stages.

Steroidogenic factor 1 (SF-1) or Ad4BP is a member of the fushi tarazu factor 1 (FTZ-F1) family and an orphan nuclear receptor that plays an important role in the hypothalamus-pituitary-gonadal axis and the adrenal cortex. Although its critical role in the differentiation of adrenals, gonads, and pituitary gonadotropes has been well demonstrated, regulatory function of SF-1 during sexual maturation is yet to be examined. To investigate the potential role of SF-1 in sexual maturation, expression of two salmon FTZ-F1 homolog genes, sFF1-I and sFF1-II, was examined in the pituitaries of chum and sockeye salmons, using specific and sensitive RNase protection assays. Only sFF1-I mRNA was found in the pituitary and other organs, such as the ovary, spleen, liver, brain, and skeletal muscle. In chum salmon during upstream migration from the bay to the hatchery, the level of sFF1-I mRNA in the male fish was increased on the midway in the river, where the levels of gonadotropin alpha- and II beta-subunit mRNAs were increased. In maturing sockeye salmon, the expression of the sFF1-I gene was elevated in the mature male fish, but the administration of GnRH analog did not further enhance the expression. These results indicate that sFF1-I gene expression in the pituitary is upregulated in maturing salmon, and this upregulation may not depend on GnRH.

Animals↗