Isolation of microorganisms from the feces of Kitasato Yakumo beef cattle as bioactive natural product producers.

We envisioned that the rumen of Kitasato Yakumo beef cattle would contain unique microorganisms which produce bioactive compounds as their defense response to the external environment. The variety of microorganisms were collected from the feces of Kitasato Yakumo beef cattle. We evaluated the biological activity of the culture broth of the isolated strains, proving the utility of our approach.

Levels of major and trace metals in the scalp hair of Crohn's disease patients: correlations among transition metals.

Concentrations of 16 metals in the scalp hair of male Crohn's disease (CD) patients (n = 28) were compared to those of male control subjects (n = 25). The majority of patients (n = 20) took an anti-inflammatory agent (mesalazine), and several patients underwent colectomy. A low concentration of serum ferritin was observed in approximately 50% of CD patients due to Fe-deficiency anemia. The concentrations of Fe, Cr, and Co in the hair of CD patients were significantly higher than those of control subjects, and particularly high concentrations were found in CD patients with low serum ferritin. Significant correlations were found among the concentrations of Fe, Cr, and Co in the hair of CD patients, but not in control subjects. In agreement with previous reports, a significant negative correlation was found between ferritin and transferrin concentrations in serum, although the available data in this study was limited (n = 8). Transferrin not only binds to Fe3+ but also to Cr3+ and Co3+, and the amount of transferrin is increased in Fe-deficiency anemia. Thus, the majority of the Fe3+, Cr3+, and Co3+ in the serum of CD patients is likely to bind to transferrin, which may be associated with the higher concentrations of those metals, as well as the significant correlations among those metals in the scalp hair of CD patients. In addition, colectomy may alter the intestinal absorption rate of some metals, while mesalazine may increase the concentrations of Mn and some metals in the scalp hair by chelate formation.

Coordinated alteration of mRNA-microRNA transcriptomes associated with exosomes and fatty acid metabolism in adipose tissue and skeletal muscle in grazing cattle.

OBJECTIVE: On the hypothesis that grazing of cattle prompts organs to secrete or internalize circulating microRNAs (c-miRNAs) in parallel with changes in energy metabolism, we aimed to clarify biological events in adipose, skeletal muscle, and liver tissues in grazing Japanese Shorthorn (JSH) steers by a transcriptomic approach. METHODS: The subcutaneous fat (SCF), biceps femoris muscle (BFM), and liver in JSH steers after three months of grazing or housing were analyzed using microarray and quantitative polymerase chain reaction (qPCR), followed by gene ontology (GO) and functional annotation analyses. RESULTS: The results of transcriptomics indicated that SCF was highly responsive to grazing compared to BFM and liver tissues. The 'Exosome', 'Carbohydrate metabolism' and 'Lipid metabolism' were extracted as the relevant GO terms in SCF and BFM, and/or liver from the >1.5-fold-altered mRNAs in grazing steers. The qPCR analyses showed a trend of upregulated gene expression related to exosome secretion and internalization (charged multivesicular body protein 4A, vacuolar protein sorting-associated protein 4B, vesicle associated membrane protein 7, caveolin 1) in the BFM and SCF, as well as upregulation of lipolysisassociated mRNAs (carnitine palmitoyltransferase 1A, hormone-sensitive lipase, perilipin 1, adipose triglyceride lipase, fatty acid binding protein 4) and most of the microRNAs (miRNAs) in SCF. Moreover, gene expression related to fatty acid uptake and inter-organ signaling (solute carrier family 27 member 4 and angiopoietin-like 4) was upregulated in BFM, suggesting activation of SCF-BFM organ crosstalk for energy metabolism. Meanwhile, expression of plasma exosomal miR-16a, miR-19b, miR-21-5p, and miR-142-5p was reduced. According to bioinformatic analyses, the c-miRNA target genes are associated with the terms 'Endosome', 'Caveola', 'Endocytosis', 'Carbohydrate metabolism', and with pathways related to environmental information processing and the endocrine system. CONCLUSION: Exosome and fatty acid metabolism-related gene expression was altered in SCF of grazing cattle, which could be regulated by miRNA such as miR-142-5p. These changes occurred coordinately in both the SCF and BFM, suggesting involvement of exosome in the SCF-BFM organ crosstalk to modulate energy metabolism.

Stable isotope ratios of carbon, nitrogen and selenium concentration in the scalp hair of Crohn's disease patients who ingested the elemental diet Elental®.

RATIONALE: Elental® is an elemental diet widely used as a nutritional supplement for Crohn's disease (CD) patients in Japan. Elental® contains amino acids as nitrogen sources and does not contain selenium (Se), and the δ13 C and δ15 N values of Elental® are markedly higher and lower, respectively, than those of a normal diet. METHODS: We compared the δ13 C and δ15 N values and Se concentration in the scalp hair of CD patients with those of control subjects who ate a regular diet, and estimated the amount of Elental® ingested as a supplement. The δ13 C and δ15 N values and the Se concentrations were quantified using isotope ratio mass spectrometry (IRMS) and inductively coupled plasma mass spectrometry (ICP-MS), respectively. RESULTS: An increase in Elental® ingestion increased the δ13 C value in the hair of CD patients (p <0.05), while it reduced the δ15 N value (p <0.05) and tended to reduce the Se concentration in female patients. CONCLUSIONS: The amount of Elental® ingested could be estimated by the δ13 C and δ15 N values in the hair of CD patients. Furthermore, the Se deficiency in female patients may be predicted from the δ13 C and δ15 N values.

Correlations between mercury concentration, and stable isotope ratios of carbon and nitrogen of amino acids in scalp hair from whale meat eaters and heavy fish eaters.

RATIONALE: As mercury (Hg) accumulation in marine animals generally increases with increased trophic level (δ15 N values) through the food web, predators accumulate higher levels of Hg. The main source of human Hg intake is the consumption of fish and other marine animals, and Hg concentration in scalp hair is the preferred marker for evaluating consumption of marine animals. Difference in δ15 N values between trophic and source amino acids of human consumers could enable us to estimate the trophic level of the consumer without knowing the bulk δ15 N value of their prey. METHODS: We measured the δ15 N values of 15 amino acids in scalp hair from heavy fish eaters and whale meat eaters using isotope ratio monitoring gas chromatography/mass spectrometry (irm-GC/MS), and investigated the correlations between Hg concentrations in the hair and the δ15 N values of the individual constituent amino acids. RESULTS: The δ15 N values for all trophic amino acids (Ala, Val, Leu, Ile, Pro, Asx and Glx) increased with increases in Hg concentration (p < 0.01), with the highest correlation being with Glx (R2  = 0.725). In contrast, the δ15 N value for Thr decreased with increases in Hg concentration (R2  = 0.663, p < 0.01). The difference in δ15 N values between Glx and Thr was positively correlated with Hg concentration, showing the highest correlation coefficient (R2  = 0.773, p < 0.01) among the various combinations for amino acids. CONCLUSIONS: The difference in δ15 N values between Glx and Thr appears to be the best proxy for the estimation of Hg concentration in scalp hair. Copyright © 2017 John Wiley & Sons, Ltd.

Mounting exhibited between cows is not associated with sexual motivation.

Females of various species exhibit mounting behavior toward other mature females, i.e., female-female (f-f) mounting. Cows exhibit f-f mounting, which is commonly considered a sexual behavior based on a few similarities with male sexual mounting. Here, we hypothesized that the degree of f-f mounting exhibited by cows in estrus would increase when they are sexually motivated by sexually relevant stimuli. To test this hypothesis, two groups of four cows each were prepared. First, estrus was induced in one of the cows in each group by injecting estradiol in the presence of a non-sexually active male steer as a stimulus animal (steer-stimulus condition), and all f-f mounts were recorded. Estrus induction was repeated until induced in all cows. We then changed the stimulus animal from the steer to a sexually active bull (bull-stimulus condition), and the estrus induction procedures were repeated as before. We confirmed that estrus was induced successfully in cows injected with estradiol and that they were sexually motivated by switching the stimulus animal from steer to bull, as they spent relatively more time with the stimulus animal in the bull-stimulus than in the steer-stimulus condition and when not in estrus. However, f-f mounting frequency in the bull-stimulus condition showed no significant difference to that in the steer-stimulus condition. We observed that six of the eight subjects exhibited f-f mounting when not in estrus, which accounted for 44.6 % of f-f mounting we observed (n = 668). These findings suggest that f-f mounting in cows is not associated with sexual motivation.

Levels of mercury in muscle and liver of star-spotted dogfish (Mustelus manazo) from the northern region of Japan: a comparison with spiny dogfish (Squalus acanthias).

We analyzed mercury (Hg) concentrations in muscle and liver samples of star-spotted dogfish (Mustelus manazo) caught off the northern region of Japan and compared them with those of spiny dogfish (Squalus acanthias) caught in the same region. The average body length of male star-spotted dogfish specimens was significantly smaller than that of female specimens, reflecting the slower growth rate of male fish. Hg concentrations in liver and muscle increased with increases in body length and estimated age of both male and female star-spotted dogfish specimens. However, the relationships between Hg concentration in liver or muscle and body length or estimated age of male specimens differed markedly from those of female specimens, reflecting differences in growth rate and cessation of growth on reaching maturity. Marked increases in Hg concentration in liver of male and female star-spotted dogfish specimens were observed slightly later than increases in Hg concentration in muscle of those specimens due to growth cessation. These marked increases in Hg in liver may reflect increases in Hg due to the formation of mercury selenide. Similar results were previously reported in spiny dogfish specimens, except spiny dogfish showed only trace levels of Hg in liver (Endo et al., Chemosphere 77:1333-1337, 2009). The greater lipid content in liver and the larger liver size in spiny dogfish may explain the much lower levels of Hg observed in liver of spiny dogfish compared with those in the star-spotted dogfish.

Levels of mercury and organohalogen compounds in the muscle and liver of kidako moray eels (Gymnothorax kidako) caught off the southern region of Japan.

We analyzed the levels of total mercury (T-Hg), methylmercury (M-Hg) and Cd in the muscle and liver of kidako moray eels (Gymnothorax kidako) of different body lengths caught off Kochi Prefecture in southern Japan. Furthermore, we analyzed the levels of organohalogen compounds such as polychlorinated biphenyls (PCBs), p,p'-1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE), trans-nonachlor and 2,3,3',4,4',5,5'-heptachloro-1'-methyl-1-2'-bipyrrole (Q1) and stable isotope ratios of carbon (δ(13)C) and nitrogen (δ(15)N) in the muscle of eels. The concentrations of T-Hg and M-Hg in the muscle (edible part) were 0.31±0.08 µg/wet g and 0.25±0.06 µg/wet g (n=26), respectively, and those in large eels exceeded the Japanese legislated levels of T-Hg (0.4 µg/wet g) and M-Hg (0.3 µg/wet g) in fish and shellfish, respectively. The T-Hg and M-Hg concentrations in the liver were markedly higher than those in the muscle, respectively. The ratios of M-Hg to T-Hg in the muscle and liver were about 80 and 60%, respectively, and those ratios tended to decrease with increased body length. The Cd concentrations in the liver tended to increase proportionally with body length, while that in the muscle was trace (around or below 0.03 µg/wet g). The concentrations of PCBs, p,p'-DDE, trans-nonachlor in the muscle tended to increase proportionally with body length, while that of Q1 did not. The δ(13)C and δ(15)N values in the kidako moray eel were markedly higher than those in offshore habit predators reported elsewhere, which may reflect the inshore habitat of this eels.

Edible insect Locusta migratoria shows intestinal protein digestibility and improves plasma and hepatic lipid metabolism in male rats.

Although edible insect migratory locusts are considered sustainable food resources with proteins and n-3 lipids, their physiological effects on lipid metabolism are not clarified. Here, we clarified the amino acid (AA) value of the edible migratory locust powder (MLP), protein digestibility, and dietary effects of MLP on growth and lipid metabolism in rats. The AA score was 63, which was low score due to the limiting AA (Trp). MLP protein digestibility was resistant to gut pepsin but digestible to intestinal trypsin and chymotrypsin. Dietary MLP represented favorable growth and enhanced intestinal condition and lipid metabolism in rats, particularly, low-density lipoprotein metabolism and arteriosclerosis-related fatty acid profiles. Liver triglyceride accumulation and fatty acid desaturation indices were increased by activating lipids uptake into the liver, while lipogenic protein expression and enzyme activities and liver function indices were reduced by MLP. Conclusively, intestinal digestible MLP is a nutraceutical for the prevention of dyslipidemia.

Anterior pituitary progenitor cells express costimulatory molecule 4Ig-B7-H3.

Stem/Progenitor cells in the postnatal pituitary gland are embedded in a marginal cell layer around Rathke's pouch. However, the nature and behavior of anterior pituitary progenitor cells remain unclear. We established bovine anterior pituitary progenitor cell line (BAPC)-1 from the anterior pituitary gland, which expressed stem/progenitor cell-related genes and several inflammatory cytokines. To characterize and localize these pituitary progenitor cells, we produced a mAb (12B mAb) against BAPC-1. The 12B mAb recognized the 4Ig-B7-H3 molecule, which is a costimulatory molecule and negative regulator in T cell activation. WC1(+) gammadelta T cells in young bovine PBMC express the 4Ig-B7-H3 molecule, but few or no 4Ig-B7-H3-immunoreactive cells are expressed in PBMC in adult cattle. The 12B-immunoreactive cells in the bovine anterior pituitary gland were localized around Rathke's pouch and expressed IL-18 and MHC class II. However, the number of 12B-immunoreactive cells was lower in adult than in young cattle. BAPC-1 expressed IL-18 and MHC class II, and demonstrated phagocytotic activity. BAPC-1 also had the ability to promote CD25 expression in PBMC after 5 days of coculture, and blocking 4Ig-B7-H3 x 12B mAb enhanced their expression of CD25. In addition, the 12B-immunoreactive cells were observed around the pars tuberalis closely bordering the median eminence and in the blood vessels of the primary portal plexus in the anterior pituitary gland. These results suggest that an established BAPC-1 may originate from these progenitor cells, and that the progenitor cells with 4Ig-B7-H3 may play a critical role in the immunoendocrine network.

Correlation between skeletal muscle fiber type and responses of a taste sensing system in various beef samples.

The difference of muscle fiber type composition affects several parameters related to meat quality; however, the relationship between muscle fiber types and meat taste is unclear. To elucidate this relationship, we determined the taste of various beef samples using a taste sensor (INSENT SA402B) and analyzed its correlation with different muscle fiber type composition. We used 22 kinds of beef samples and measured nine tastes, including the relative and change of membrane potential caused by adsorption (CPA) values, using six sensors (GL1, CT0, CA0, AAE, C00, and AE1). The taste sensor analysis indicated positive value outputs for the relative C00, AAE, and GL1 values as well as for the CPA value of AAE, which corresponded to bitterness, umami, sweetness, and richness, respectively. We found significant positive correlations of the myosin heavy chain 1 (MyHC1) composition with umami taste, and with richness. This result suggests that high levels of slow MyHC1 can induce strong umami taste and richness in beef. We expect that our results will contribute to the elucidation of the relationship between muscle fiber types and meat palatability.

[A case of thoracic empyema caused by Actinomyces species nova].

A 50-year-old man was referred and admitted to our hospital because of pneumonia and pleuritis. The patient had attempted suicide by inhaling automobile exhaust 3 years ago. Carbon monoxide intoxication had caused persistent disturbance of consciousness and quadriplegia. He had been tracheostomised and under nutrition by percutaneous endoscopic gastrostomy. On admission the presence of left pleural fluid with thickening of the pleura was shown on computed tomography. Thoracocentesis produced suppurative fluid with Actinomyces species nova identified by the 16S rRNA method. The patient was successfully treated with antibiotics and drainage of suppurative fluid.

Expression of inflammatory-related factors in porcine anterior pituitary-derived cell line.

Recent studies have shown that undifferentiated stem cells act as immunomodulators. To investigate the immunomodulatory function of the progenitor cells of the anterior pituitary gland, we attempted to establish a stem/progenitor cell line from the porcine anterior pituitary gland, and to detail its inflammatory cytokine expression. A cloned cell line from the porcine anterior pituitary gland was established and was designated as the porcine anterior pituitary-derived cell line (PAPC). PAPC expressed the mRNA of Nanog and Oct-4, and showed positive immunoreactivity for beta-catenin and Hes1 in its nucleus. PAPC grew stably by repeated passage and rapidly in the EGF and bFGF containing medium. RT-PCR showed that PAPC expressed mRNA of IL-1alpha, IL-6, IL-12, IL-15, IL-18 and TLR4. PAPC expressed S100alpha and IL-18 protein, which was localized in the marginal epithelial cells of Rathke's pouch. These results suggest that PAPC is a stem/progenitor cell and may regulate anterior pituitary cell function through an immuno-endocrine pathway.

Localization of leptin and leptin receptor in the bovine adenohypophysis.

The present study was carried out to detail the cellular localization of leptin (Lep) and the leptin receptor (LepR) in the bovine adenohypophysis. Lep immunoreactivity (Lep-ir) was found in about 30% of adenohypophysial cells in the gland. Immunochemistry of Lep and specific hormones using serial sections revealed that Lep-ir was present in 60.4% of somatotrophs, 15.9% of gonadotrophs, 6.5% of mammotrophs, 6.5% of thyrotrophs and 2.4% of corticotrophs. Both the common short isoform (OBRa) and the long isoform (OBRb) of LepR mRNA were expressed in the bovine adenohypophysis. LepR immunoreactivity (LepR-ir) was found in only 2.8% of the adenohypophysial cells and over 50% of LepR-ir cells were gonadotrophs, in which most of the cells were distributed in the zona tuberalis. The findings on Lep and LepR in the adenohypophysial cells indicate that Lep may regulate gonadotroph function through autocrine/paracrine pathway in the bovine adenohypophysis.

Presence of neuropeptide Y in somatotrophs of cattle.

Neuropeptide Y (NPY), a 36-amino acid member of the pancreatic polypeptide family, was found to be present by immunohistochemistry in the bovine adenohypophysis. NPY mRNA expression was confirmed in the adenohypophysis by RT-PCR. NPY immunoreactivity was present in about 38% of adenohypophyseal cells in the pars distalis. However, NPY immunoreactive cells (NPY-ir cells) were scarce in the zona tuberalis. Immunohistochemistry of NPY and specific hormones using mirror sections revealed that NPY was colocalized in GH immunoreactive cells. Over 90% of somatotrophs corresponded to NPY-ir cells. These results indicate that endogenous NPY is present in the bovine somatotroph and may act as an endocrine intercellular mediator in the adenohypophysis.

[New criteria for discharge from ward in patients with pulmonary tuberculosis using mycobacteria growth indicator tube].

OBJECTIVES: To find a new method to predict the result of the egg based Ogawa medium using the Mycobacterium Growth Indicator Tube (MGIT) system and to evaluate the usefulness of a new discharge criterion that uses the new prediction method for smear positive pulmonary tuberculosis patients. MATERIALS AND METHODS: We compared mycobacterial growth of sputum specimens weekly between the Mycobacterium Growth Indicator Tube (MGIT) and the egg based Ogawa solid media, using a total of 3952 sputum specimens of patients with pulmonary tuberculosis (TB) who underwent chemotherapy in our hospital from September 2001 to March 2006 to find relationship between the results of the two culture methods and to utilize the findings to new discharge criteria of pulmonary TB patients. And we compared the duration of hospitalization between two patients' group: one group using the new discharge criterion, the other the old one. RESULTS: We found that if a specimen shows negative culture on the MGIT system within the first two weeks, the same specimen shows negative or scant growth on the Ogawa media in the 8th week. Introducing this fact as a part of new criteria for hospital discharge of patients with pulmonary tuberculosis, the median duration of hospitalization in our hospital was shortened from 121 days to 71 days and no patient showed treatment failure. DISCUSSION: We have used the result of sputum culture on Ogawa medium as a standard when we judge infectivity of patients with pulmonary tuberculosis in Japan, but it was one of the reasons why Japanese pulmonary tuberculosis patients stay long in TB hospital. Using our finding, we can predict the results of Ogawa system six weeks earlier, when a specimen shows negative culture on the MGIT system in the first 2 weeks. After we introduced this fact into new criteria for hospital discharge of patients with pulmonary tuberculosis, the median duration of hospitalization in our hospital was shortened and no patient shows treatment failure until now. We highly recommend the usefulness of the MGIT system (especially when a specimen shows negative growth in the first two weeks) as a reliable method of predicting infectivity of patients with pulmonary tuberculosis and propose that the new TB discharge criterion should be widely confirmed and used in other hospitals.

Serotonin Improves High Fat Diet Induced Obesity in Mice.

There are two independent serotonin (5-HT) systems of organization: one in the central nervous system and the other in the periphery. 5-HT affects feeding behavior and obesity in the central nervous system. On the other hand, peripheral 5-HT also may play an important role in obesity, as it has been reported that 5-HT regulates glucose and lipid metabolism. Here we show that the intraperitoneal injection of 5-HT to mice inhibits weight gain, hyperglycemia and insulin resistance and completely prevented the enlargement of intra-abdominal adipocytes without having any effect on food intake when on a high fat diet, but not on a chow diet. 5-HT increased energy expenditure, O2 consumption and CO2 production. This novel metabolic effect of peripheral 5-HT is critically related to a shift in the profile of muscle fiber type from fast/glycolytic to slow/oxidative in soleus muscle. Additionally, 5-HT dramatically induced an increase in the mRNA expression of peroxisome proliferator-activated receptor coactivator 1α (PGC-1α)-b and PGC-1α-c in soleus muscle. The elevation of these gene mRNA expressions by 5-HT injection was inhibited by treatment with 5-HT receptor (5HTR) 2A or 7 antagonists. Our results demonstrate that peripheral 5-HT may play an important role in the relief of obesity and other metabolic disorders by accelerating energy consumption in skeletal muscle.

[Relationship between pollen allergy and oral allergy syndrome].

We recently evaluated the relationship between pollen allergy and oral and pharyngeal hypersensitivity to fruits and vegetables (oral allergy syndrome) over 8 years (1995 approximately 2002) in Sapporo. 1. Of 843 patients with birch pollen (BP) allergy (CAP score 2 or more), 378 patients (37%) had episodes of oral allergy syndrome (OAS), and the rate in BP allergy was higher than in other allergies. 2. In patients with BP allergy, the most frequent foods causing OAS were apple, peach and cherry, followed by kiwi, pear, plum and melon. BP allergy patients demonstrated much more OAS with these foods than the patients without BP allergy. The higher the CAP score of BP, the higher the incidence of OAS to these foods was found to be. In patients with OAS and BP allergy, the higher the CAP score of BP, the higher the number of foods causing OAS was found to be. 3. In patients with BP allergy, a multiple logistic regression analysis was performed to identify factors affecting the rate of OAS. Positive factors were a high BP CAP score and being female. A negative factor was mite CAP positive. Furthermore, mugwort pollen (MP) CAP positive patients had much more OAS to kiwi and tomato than MP CAP negative patients.

Grazing Affects Exosomal Circulating MicroRNAs in Cattle.

Circulating microRNAs (c-miRNAs) are associated with physiological adaptation to acute and chronic aerobic exercise in humans. To investigate the potential effect of grazing movement on miRNA circulation in cattle, here we profiled miRNA expression in centrifugally prepared exosomes from the plasma of both grazing and housed Japanese Shorthorn cattle. Microarray analysis of the c-miRNAs resulted in detection of a total of 231 bovine exosomal miRNAs in the plasma, with a constant expression level of let-7g across the duration and cattle groups. Expression of muscle-specific miRNAs such as miR-1, miR-133a, miR-206, miR-208a/b, and miR-499 were undetectable, suggesting the mildness of grazing movement as exercise. According to validation by quantitative RT-PCR, the circulating miR-150 level in the grazing cattle normalized by the endogenous let-7g level was down-regulated after 2 and 4 months of grazing (P < 0.05), and then its levels in housed and grazing cattle equalized when the grazing cattle were returned to a housed situation. Likewise, the levels of miR-19b, miR-148a, miR-221, miR-223, miR-320a, miR-361, and miR-486 were temporarily lowered in the cattle at 1 and/or 2 month of grazing compared to those of the housed cattle (P < 0.05). In contrast, the miR-451 level was up-regulated in the grazing cattle at 2 months of grazing (P = 0.044). The elevation of miR-451 level in the plasma was coincident with that in the biceps femoris muscle of the grazing cattle (P = 0.008), which suggests the secretion or intake of miR-451 between skeletal muscle cells and circulation during grazing. These results revealed that exosomal c-miRNAs in cattle were affected by grazing, suggesting their usefulness as molecular grazing markers and functions in physiological adaptation of grazing cattle associated with endocytosis, focal adhesion, axon guidance, and a variety of intracellular signaling, as predicted by bioinformatic analysis.

Grazing-induced changes in muscle microRNA-206 and -208b expression in association with myogenic gene expression in cattle.

To investigate the roles of microRNAs (miRNAs) in muscle type conversion, the effects of 4 months of grazing on the expression levels of miRNAs and mRNAs associated with skeletal muscle development were analyzed by quantitative RT-PCR using the Biceps femoris muscle of Japanese Shorthorn cattle. After 4 months of grazing, the expression of muscle fiber type-associated miR-208b was higher in the grazed cattle than in the housed. In concordance with the pattern in miR-208b expression, the expression of MyoD, a myogenic regulatory factor associated with the shifting of muscle property to the fast type, was lower in the grazed cattle after 4 months of grazing than in the housed cattle. In addition, the expression of MyHC-2x (a fast type) was higher in the housed cattle than in the grazed, after 4 months of grazing. During the grazing period, miR-206 expression decreased in the housed cattle, whereas expression in the grazed cattle did not change, but rather remained higher than that of the housed cattle even at 3 months after the grazing ended. These miRNAs including miR-206 persisting with muscles of grazed cattle may be associated with regulation of muscle gene expression during skeletal muscle adaptation to grazing.