Effects of testosterone on rat placental development

We investigated the morphological effects of testosterone on placental development in a rat model of polycystic ovarian syndrome (PCOS). Testosterone propionate (TP), which was subcutaneously administered to pregnant rats with 5 mg/animal from gestation day (GD) 14 to GD 18, induced a maternal weight reduction without mortality or clinical signs from GD 19 onwards. A decrease in fetal and placental weight, an increase in intrauterine growth retardation (IUGR) rates, and histological changes in the placenta were observed on GD 21 but not on GD15 or 17. Histopathologically, on GD 21, the trophoblast septa thickened, and the maternal sinusoids were narrowed in the labyrinth zone, resulting in a small placenta. Additionally, the placental weight, thickness, and histological morphology in the labyrinth zone on GD 21 in the TP-treated group were nearly identical to those on GD 17 in the control and TP-treated groups. Therefore, it was assumed that the testosterone-induced small placenta was induced in association with the developmental inhibition of the fetal part of the placentas from GD 17 onwards.     

Genetic variability and stock structure of red tilefish Branchiostegus japonicus inferred from mtDNA sequence analysis

Sequence analysis based on the anterior part of the mitochondrial DNA control region was carried out to reveal the genetic diversity, stock structure, and historical demography of the red tilefish. Nucleotide sequences of 388 bp in length were determined for 280 individuals taken from eight localities. The molecular diversity, haplotype diversity, and nucleotide diversity were relatively high (average h = 0.929 ± 0.011; average π = 0.008 ± 0.005). The mismatch distribution was not significantly different from the expected distribution for a rapidly expanding population (P = 0.453). The minimum spanning network connecting with full-sequence haplotypes contained star-like topologies derived from multiple ancient lineages, supporting the mismatch distribution analysis. No significant genetic differentiation was observed among eight localities (maximum pairwise F _ST = 0.023, reduced-sequence data set). Our results suggest a large panmictic population of the red tilefish along the coast of Honshu to the East China Sea.     

Ubiquitous increase in taurine transporter mRNA in tissues of tilapia (Oreochromis mossambicus) during high-salinity adaptation

We have isolated a cDNA encoding the taurine transporter from a tilapia (Oreochromis mossambicus) gill cDNA library. Transient expression of the cDNA in COS-7 cell indicates that the clone encodes a Na⁺- and Cl^–-dependent and -amino acid-specific taurine transporter. By the transfer of tilapia cultured in freshwater to 70% artificial seawater, plasma osmolality increased by up to 100–135 mOsm/kgH₂O along with the marked increase in the taurine transporter mRNA level in all the tissues examined i.e., kidney, stomach, intestine, gill, eye, liver, fin, muscle and brain. In most tissues, time-dependent change in the taurine transporter mRNA level corresponds to that in plasma osmolality. However, fin showed an acute and muscle showed a delayed increase in taurine transporter mRNA compared to changes in plasma osmolality. The taurine transporter mRNA level in tilapia embryos also increased after transfer from freshwater to 100% artificial seawater. Increase in taurine transporter expression leads to the activation of cellular uptake of taurine from plasma and the accumulation of taurine in the cell. Thus the results in the present study suggest that taurine plays an important role as an osmolyte in the ubiquitous tissues of tilapia during high-salinity adaptation.     

Effect of artemia nauplii enriched with vitamin A palmitate on hypermelanosis on the blind side in juvenile Japanese flounder Paralichthys olivaceus

ABSTRACT:   The effect of Artemia nauplii enriched with different level of vitamin A (VA) palmitate (1 µg = 1 IU) on the occurrence of hypermelanosis on the blind side of Japanese flounder Paralichthys olivaceus was determined. Artemia were enriched with 0, 1, 2, 5 or 10 mg VA palmitate/L (control group, and 1-, 2-, 5-, and 10-mg groups). The enriched Artemia were fed to the larvae from 27 to 31 days post hatching (dph) corresponding to the F–G stage. VA palmitate, retinol and retinoic acid (RA) contents of Artemia were correlatively elevated with increasing VA palmitate in the culture medium. RA was detected in Artemia enriched with 5 mg and 10 mg, and a significantly high frequency of hypermelanosis on the blind side was observed in these groups at 65 dph ( P  < 0.05). These results suggest that RA synthesized from VA palmitate in Artemia could induce hypermelanosis on blind side of flounder when Artemia are enriched with more than 5 mg VA palmitate/L.     

Effects of high dose of vitamin A on reproduction and egg quality of Japanese flounder Paralichthys olivaceus

ABSTRACT: The present study was conducted to investigate the effects of dietary vitamin A on reproduction and egg quality in Japanese flounder Paralichthys olivaceus . Broodstock were fed experimental pellets containing two levels of vitamin A [11 × 10³ IU/100 g (control diet; CD), 337 × 10³ IU/100 g (experimental diet; ED)] for approximately 2 months before spawning and during the spawning period. Two groups of five females (average weight 1.4 kg) and 10 males (average weight 0.7 kg) were randomly allocated to two 30 m³ indoor tanks. Total egg production of the CD group was slightly higher than the ED group. Percentage of buoyant eggs and hatching rate of the ED group were significantly higher than the CD. In other egg quality parameters, such as percentage abnormal larvae and starvation tolerance of larvae, no notable difference was found between these two groups. At the end of the experiment, the skin color of broodstock in the ED group was darker than that of the CD group. Vitamin A content in eggs of the ED group was significantly higher than that of the CD group. However, the difference in vitamin A content in eggs between the ED and CD groups was much smaller than that in the liver of the females between the two groups. These results indicate that feeding broodstock a higher level of vitamin A increases the vitamin A content in eggs but does not affect egg quality in Japanese flounder because excess dietary vitamin A was stored mainly in the broodstocks' liver.     

Quantitative assessment of muscle mass and gene expression analysis in dogs with glucocorticoid-induced muscle atrophy

The present study aimed to quantitatively evaluate muscle mass and gene expression in dogs with glucocorticoid-induced muscle atrophy. Five healthy beagles received oral prednisolone for 4 weeks (1 mg/kg/day), and muscle mass was then evaluated via computed tomography. Histological and gene expression analyses were performed using biopsy samples from the biceps femoris before and after prednisolone administration. The cross-sectional area of the third lumbar paraspinal and mid-femoral muscles significantly decreased after glucocorticoid administration (from 27.5 ± 1.9 to 22.6 ± 2.0 cm² and from 55.1 ± 4.7 to 50.7 ± 4.1 cm², respectively; P<0.01). The fast- and slow-twitch muscle fibers were both atrophied (from 2,779 ± 369 to 1,581 ± 207 μm² and from 2,871 ± 211 to 1,971 ± 169 μm², respectively; P<0.05). The expression of the growth factor receptor-bound protein 10 (GRB10) significantly increased after prednisolone administration (P<0.05). Because GRB10 suppresses insulin signaling and the subsequent mammalian target of rapamycin complex 1 activity, increased expression of GRB10 may have resulted in a decrease in protein anabolism. Taken together, 1 mg/kg/day oral prednisolone for 4 weeks induced significant muscle atrophy in dogs, and GRB10 might participate in the pathology of glucocorticoid-induced muscle atrophy in canines.     

Quantitative structure-activity analysis of larvicidal 1-(substituted benzoyl)-2-benzoyl-1-tert-butylhydrazines against Chilo suppressalis

The larvicidal activity of a number of 1-(substituted benzoyl)-2-benzoyl–1 -ten-butylhydrazines against the rice stem borer (Chilo suppressalis Walk.) was measured. Variations in the activity were examined quantitatively using physico-chemical substituent and molecular parameters and regression analysis. The results indicated that the molecular hydrophobicity and the electron-withdrawing inductive/ field effect of ontho substituents are favourable to larvicidal activity. The bulkiness of substituents at the meta and para positions was unfavourable to activity, substitution at the para position being more unfavourable than that at the meta position in terms of van der Waals' volume. The 2,3–, 2,5- and 2,6-disubstitution patterns were also unfavourable to activity. Reductions in larvicidal activity caused by the 2,6-,- 2,3,5- and 2,3,4,5-substitutions were greater than those induced by the 2,3- and 2,5-disubstitutions. When the sum of contributions from favourable effects is greater than that from unfavourable effects, the larvicidal activity is expected to be superior to that of the unsubstituted compound.     

New severe strains of Melon necrotic spot virus: symptomatology and sequencing

New strains of Melon necrotic spot virus (MNSV), designated MNSV-YS and MNSV-KS, caused much more severe growth retardation on melon plants than MNSV-NH, which was previously reported as the most severe strain of MNSV in Japan. MNSV-YS spread much more quickly than MNSV-NH in infected plants, and induced more severe growth retardation, even though the appearance of necrotic lesions on inoculated cotyledons was much slower. MNSV-KS had properties intermediate between those of the other two strains. The results suggest that faster-spreading strains can multiply more rapidly as a result of lower levels of activity in inducing necrotic lesions in melon plants. The complete sequences of MNSV-YS and MNSV-KS were determined, and an RT–PCR–RFLP method based on these sequences was successfully developed to detect and discriminate between the three strains.     

Differences between carcass grades in some morphological, behavioral and physiological measurements at early and middle stages of fattening in crossbred steers

The differential variables for carcass grades were identified from morphological, behavioral and physiological measurements of young steers at a commercial farm. Thirty‐five Japanese Black × Holstein steers aged 6–10 months were randomly assigned to three pens. The steers had free access to ryegrass hay and a restricted amount of concentrate diet for the first 6 months of trial. They were then given oat straw ad libitum and an additional concentrate diet until slaughter. Behavioral observations (15 categories) were carried out once every 2 weeks for 2 h after feeding. Bodyweight was measured, blood sampled (for seven metabolic hormones and five metabolites), ultrasonic scanning conducted and physical measurements taken (10 parts for each animal) in months 1, 3 and 5 (early fattening stage, EFS) and in months 7, 9 and 11 (middle fattening stage, MFS) of the trial. Temperament scores during these procedures, entry order into restraint stalls, social rank and average daily gain were also assessed. A factor analysis and one‐way anova were used to identify clusters of variables which had different factor scores between carcass grades. As for the carcass yields, a cluster of chest girth and depth, bodyweight, withers and hip height, and rump length (P < 0.01), and a cluster of the frequency of scratching the body with facilities (P < 0.05) were identified as differential variables in the EFS. In the MFS, a cluster of concentrations of cortisol and epinephrine, and the frequency of eating straw were identified (P < 0.10). As for the carcass quality grade, a cluster of social rank, triglyceride concentration and the frequencies of stand‐chewing cud and eating hay, and a cluster of the frequency of investigating facilities (both P < 0.10) were identified in the EFS. In the MFS, a cluster of hip height, bodyweight, cannon circumference, chest depth, withers height and chest girth, and a cluster of the frequencies of eating a concentrate diet and stand‐chewing the cud, and social rank (both P < 0.10) were identified. In conclusion, bodyweight, chest girth and depth, withers and hip height were identified as good differential variables for future carcass grades of young steers. Facility enrichment that encourages steers to eat hay in the EFS, and to eat a concentrate diet in and after the MFS would be effective in upgrading carcass grades. High incidence of investigating and scratching the body with facilities and stand‐chewing the cud might lead to lower carcass grades.