Ghrelin differentially modulates the GH secretory response to GHRH between the fed and fasted states in sheep

The effect of energy balance on the growth hormone (GH) secretory responsiveness to growth hormone-releasing hormone (GHRH) has not been determined in ruminant animals. Therefore, we examined the effects of intravenous injections of 0, 3.3, and 6.6 μg ghrelin/kg body weight (BW), with and without GHRH at 0.25 μg/kg BW, on GH secretory responsiveness in both the fed and fasted sheep. The injections were carried out at 48 h (Fasting state) and 3 h (Satiety state) after feeding. Blood samples were taken every 10 minutes, from 30 minutes before to 120 minutes after the injection. Low (3.3 μg/kg BW) and high (6.6 μg/kg BW) doses of ghrelin stimulated GH secretion significantly (P < .05) greater in the Satiety state than in the Fasting state. Growth hormone-releasing hormone plus both doses of ghrelin stimulated GH secretion significantly (P < .05) greater in the Satiety state than in the Fasting state. Ghrelin and GHRH exerted a synergistic effect in the Satiety state, but not in the Fasting state. Plasma ghrelin levels were maintained significantly (P < .05) greater in the Fasting state than in the Satiety state except the temporal increases after ghrelin administration. Plasma free fatty acid (FFA) concentrations were significantly (P < .01) greater in the Fasting state than in the Satiety state. In conclusion, the present study has demonstrated for the first time that ghrelin differentially modulates GH secretory response to GHRH according to feeding states in ruminant animals.     

Impaired Development of Somatotropes, Lactotropes and Thyrotropes in Growth-Retarded (grt) Mice

Congenitally primary hypothyroid growth-retarded (grt) mice exhibit a characteristic growth pause followed by delayed onset of pubertal growth. We characterized the developmental pattern of somatotropes, lactotropes and thyrotropes in the anterior pituitary, as well as plasma levels of their secretory hormones, in grt mice. Compared with normal mice, the weight of grt pituitary gland was similar at 8 weeks of age but significantly heavier after 12 weeks of age. Compared with normal mice, there were significantly fewer somatotropes in the grt pituitary until 8 weeks of age, but the number gradually increased up to 48 weeks. The number of lactotropes in grt mice was consistently lower than that in normal mice from 2 through 48 weeks, whereas the number of thyrotropes in the grt pituitary was consistently higher than in the normal pituitary. Thyrotropes in the grt pituitary exhibited hypertrophy and hyperplasia with less intensive thyroid-stimulating hormone (TSH) immunoreactivity than normal thyrotropes. In normal mice, the sum of the relative proportions of these cells plateaued at 8 weeks, where it remained up to 48 weeks of age. In grt mice, these proportions almost reached normal levels at 12 weeks of age but gradually declined after 24 weeks. Plasma growth hormone concentrations did not differ between grt and normal mice until 24 weeks of age. Compared with normal mice, grt mice exhibited significantly lower plasma prolactin and thyroxine levels but higher TSH levels. These findings indicate that development of somatotropes, lactotropes and thyrotropes in grt mice is impaired, being followed by altered hormone secretion.     

Incidence of Error in Oestrus Detection Based on Secondary Oestrus Signs in a 24-h Tie-Stalled Dairy Herd with Low Fertility

Oestrus detection error and conception rates after AI based only on secondary oestrus signs were evaluated in a high yielding, 24-h tie-stalled dairy herd with low fertility, using milk progesterone profiles. Oestrus detection was based on the secondary oestrus signs such as restlessness, swelling, congestion of vulva and clear mucus discharge. Sixty eight AI conducted after observing the secondary oestrus signs in 44 animals were included in the study. Of the 68 AI, 53 (77.9%) were conducted in the follicular phase, and 13 (19.1%) and 2 (2.9%) were carried out in the luteal phase and during pregnancy, respectively. The overall error in oestrus detection based on milk progesterone profiles was 22.1%. The oestrus detection error did not differ significantly among different secondary oestrus signs. None of the AI conducted in the luteal phase resulted in conception, whereas 20.8% of AI conducted in the follicular phase resulted in conception. No significant difference in the conception rates among the groups of cows with different secondary oestrus signs was shown. The high incidence of oestrus detection error in this study might have been caused by the detection of cows in oestrus based only on secondary oestrus signs due to the confinement of animals. In conclusion, there was a high incidence of heat detection error in the 24-h tie-stalled dairy herd and oestrus detection based only on secondary oestrus signs resulted in low conception rate.     

Production and characterization of recombinant Manchurian trout thyrotropin

Thyrotropin (thyroid-stimulating hormone, TSH), a heterodimeric glycoprotein hormone produced in the pituitary, stimulates the thyroid gland and release of thyroid hormones. In contrast to a well-known efficacy of recombinant mammalian TSHs, there is no report about the production of teleost recombinant TSH and its biological activity. In this study, we report the production of a single-chain recombinant TSH (mtTSH) of Manchurian trout (Brachymystax lenok), by baculovirus in silkworm (Bombyx mori) larvae. The mtTSH was produced in silkworm larvae and characterized as a form of N-linked glycosylation. The cAMP signaling system in transiently transfected COS-7 cells revealed that the mtTSH was recognized by their cognate receptors, salmon TSHα and TSHβ receptors, but not LH receptor. The thyrotropic potency of the mtTSH was examined by rainbow trout basibranchial tissues containing thyroid follicles. The height of follicle epithelial cells was significantly increased by treatments of mtTSH in vivo and in vitro. In conclusion, the present study suggests that the mtTSH produced by baculovirus–silkworm larvae is a biologically active recombinant TSH.     

Isolation and characterization of the rbcS genes from a sterile mutant of Ulva pertusa (Ulvales,Chlorophyta) and transient gene expression using the rbcS gene promoter

We isolated two different genomic DNAs (UprbcS1 and UprbcS2) encoding the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase and portions of the 5′- and 3′-flanking regions from sterile Ulva pertusa Kjellman. The UprbcS1 and UprbcS2 genes had three introns in the coding region. Each predicted UprbcS polypeptide was a 180-amino-acid (AA) residue including a 38-AA transit peptide, although the 104th AA residue was replaced. The nucleotide sequences of UprbcS cDNAs isolated from a cDNA library corresponded to that of the UprbcS1 gene, suggesting that the UprbcS1 gene was predominantly expressed in sterile U. pertusa compared to UprbcS2. Southern blot analysis showed that each UprbcS gene was a single-copy gene in the sterile U. pertusa genome. Northern hybridization indicated that the expression of UprbcS was induced and repressed by dark and light treatments, respectively. When sterile U. pertusa cells were transformed with an expression vector containing the UprbcS1 promoter and terminator sequences fused with the green fluorescent protein (GFP) gene, GFP fluorescence was observed in the cells transformed. These results suggest that the UprbcS1 gene promoter is light regulated and highly active in the sterile U. pertusa cells and is available for genetic transformation system in the alga.     

Recruitment and movement of the hard clam Meretrix lusoria in a tidal river of northern Kyushu,Japan

Size-frequency distributions of Meretrix lusoria, a commercially important bivalve in Japan, were compared among 6 sites in tidal flats of a small river in Kafuri Bay, northern Kyushu, Japan during 2006–2008. In Kafuri Bay, the hard clam resource is strictly managed and mean biomass of this species on the fishing ground (about 1.5 km²) exceeded 1.5 kg m^?2 in 2008. Small clams (<5 mm in shell length, SL) were most abundant in the border area between the river and the sea, while large clams (>40 mm SL) were rare there. In contrast, in the lower site of the marine area (site L), most clams were >30 mm SL. These results indicate that small clams move from riverine to marine areas with growth (post-settlement movement). Year-round, very small clams (<1 mm SL) were present and clams that were 2–5 mm SL were very rare, although the spawning season is thought to occur in summer. Probably, the early growth of many new recruits is very slow and most may even be <1 mm SL in the next spring, although some clams grow to >5 mm SL in a short period of time.     

Effect of combination feeding of <Emphasis Type="Italic">Nannochloropsis</Emphasis> and freshwater <Emphasis Type="Italic">Chlorella</Emphasis> on the fatty acid composition of rotifer <Emphasis Type="Italic">Brachionus plicatilis</Emphasis> in a continuous culture

ABSTRACT:   A continuous culture of rotifer was conducted to investigate the effect of combination feeding of both a high density of Nannochloropsis oculata (N) and condensed freshwater Chlorella (FC) on the fatty acid composition of L-type rotifer Brachionus plicatilis in a continuous culture system. The algal feeding of the rotifers was carried out in three successive steps: N-feeding → N+FC-feeding → FC-feeding. The culture was conducted at 24°C and 25–27 psu in a 2000 mL bottle with 50% of water exchanged daily. The combination N+FC-feeding was effective in increasing rotifer density. The rotifers fed on N+FC (N+FC-R) had more non-polar lipids than polar ones, similar to those on N (N-R), opposite to the rotifers fed on FC (FC-R). N+FC-R contained higher levels of 16:2, 18:2n-6 (linoleic acid [LA]) and 20:2n-6, but lower levels of 18:1, 20:4n-6 (arachidonic acid), 20:5n-3 (eicosapentaenoic acid [EPA]) and 22:5n-3 (docosapentaenoic acid [DPA]) compared with N-R. Whereas N+FC-R contained higher levels of 16:1n-7, EPA and DPA, but lower levels of 16:2 and LA compared with FC-R. N+FC-R had more DPA in polar lipids than in non-polar ones. The Σn-6/Σn-3 ratio in N+FC-R was 0.9–1.0, significantly different from those in N-R (0.4) and FC-R (6.6–8.4). Therefore, it is inferred that the fatty acid profile of the N+FC-R cultured in a continuous culture system was affected by both N and FC. Also, the combination N+FC-feeding may be effective in manipulating the Σn-6/Σn-3 ratio in continuously cultured rotifers.     

Occurrence and distribution during the post-settlement stage of two Choerodon species in shallow waters around Ishigaki Island, southern Japan

The recruitment patterns of black-spot tuskfish Choerodon schoenleinii were compared with those of orange-dotted tuskfish (OT) C. ancholago. Individuals at the settlement and juvenile stages were collected using a push net in the intertidal zone and a seine net in seagrass beds. Relative values of standard length to total length (TL) for the two Choerodon species indicated an inflection point at approximately 10?C20?mm TL, suggesting that both species complete metamorphosis at a similar size. However, their temporal and spatial occurrence patterns were distinct. Newly settled individuals (postflexion stage) of black-spot tuskfish were collected mainly within foliage of Sargassum plants of the intertidal zone around March?CApril, while those of OT occurred in both the intertidal zone and seagrass beds mainly in May and June. In seagrass beds, the abundances of both species increased from May or June; however, the TL of black-spot tuskfish was bigger than that of OT. Therefore, black-spot tuskfish progressively migrate to seagrass beds after settling and completing metamorphosis in the intertidal zone, indicating that they utilize two different habitats as nursery grounds. Early spawning and migration from the intertidal zone by this species contributed to the occurrence of relatively large individuals in seagrass beds.     

Otolith development and daily increment formation in laboratory-reared larval and juvenile black-spot tuskfish <Emphasis Type="Italic">Choerodon schoenleinii</Emphasis>

Microstructures of lapilli were examined for reared larvae and juveniles of black-spot tuskfish Choerodon schoenleinii. Lapilli of larvae at 1 day after hatching have one diffuse and obscure ring with an otolith radius of 4.3 ± 0.50 μm (mean ± SD, N = 8). The slope and intercept of the regression between the number of days after hatching and increment counts did not differ significantly from one and zero, respectively, indicating that lapillus increments were formed on a daily basis after hatching. There was an ontogenetic shift in the relative values of somatic and otolith growth, which corresponded to the transition from pelagic larvae to settlement stage. Simultaneously, the daily increment width reached the maximum value. These findings suggest that age at maximum value of increment width can be used as an indicator of the planktonic larval duration while settlement mark is not found. Since ontogenetic shift in the relationship between otolith radius and body size was observed, back-calculation of somatic growth in black-spot tuskfish using the otolith radius during the early life stages should be analyzed with caution, and the method requires further validation.     

Influence of induced cholestasis on pharmacokinetics of digoxin and digitoxin in dogs

Dogs with ligated common bile ducts were used to determine effects of cholestasis on pharmacokinetics of digoxin and digitoxin. Forty-three dogs were assigned to: group 1--sham-operated controls (n = 13); group 2--dogs with ligated common bile duct (n = 17); group 3--dogs given phenobarbital for 2 weeks before common bile duct was ligated (n = 11); or group 4--dogs with an induced biliary fistula (n = 2). Digoxin (group A) or digitoxin (group B) was given as single IV injections, and digitalis concentration in plasma was measured by radioimmunoassay. In 18 dogs given digoxin, differences in plasma digoxin concentrations among groups 1A to 3A were not significant (P greater than 0.1). Plasma elimination rate of digoxin was delayed in group 2A. Group-3A dogs had a shortened beta phase half-life (t1/2 (beta] and a decreased distribution volume. In 25 dogs given digitoxin, group-2B dogs maintained a significantly higher plasma digitoxin concentration (P less than 0.01) and had a significantly longer t1/2 (beta] than did dogs in groups 1B and 3B (P less than 0.05). In group-3B dogs, plasma digitoxin concentration was decreased and t1/2 (beta] of digitoxin was shortened. In 10 group-B dogs given 3H-digitoxin (groups 1B, 2B, and 4B), the excretion of total radioactivity in urine and bile was 15 to 20 and 7% of the dose, respectively in the first 24 hours. Most radioactivity in urine and bile was a dichloromethane-unextractable fraction.(ABSTRACT TRUNCATED AT 250 WORDS)