Regulation of taste-active components of meat by dietary leucine

1. Regulation of meat taste is one effective method for improvement of meat quality. In this study, effects of dietary leucine (Leu) content on taste-active components, especially free glutamate (Glu), in meat were investigated. 2. Broiler chickens (28 d old) were fed on diets with graded dietary Leu content (100, 130 or 150% of Leu requirement in NRC, 1994) for 10 d before marketing. Taste-active components of meat (free amino acids and ATP metabolites) and sensory score of meat soup were estimated. 3. Free Glu content, the main taste-active component of meat, was significantly increased by dietary Leu. Compared with the Leu 130% group, free Glu was increased by 17% in the Leu 100% group. Free Glu of meat tended to decrease in the Leu 150% group. In contrast, inosine monophosphate content in meat did not change among all groups. 4. Sensory evaluation of meat soup from the Leu 100 and 150% groups showed that they had different meat tastes. Sensory scores of overall preference, umami taste and chicken-like taste were significantly higher in the Leu 100% group. 5. These results suggest that dietary Leu content is a regulating factor of free Glu in meat. Decreasing dietary Leu induces an increase in the free Glu content of meat and improves meat taste.     

Characterization of mutations in the two-component histidine kinase gene that confer fludioxonil resistance and osmotic sensitivity in the os-1 mutants of Neurospora crassa

Osmotic-sensitive (os-1) mutant alleles in Neurospora crassa exhibit resistance to dicarboximides, aromatic hydrocarbons and phenylpyrroles. We have previously reported that the os-1 mutants can be classified into two groups based on their resistance to fungicides and osmotic stress: type I, which are highly resistant to iprodione and fludioxonil but moderately sensitive to osmotic stress, and type II, which are highly sensitive to osmotic stress but moderately resistant to fungicides. To explain the mechanism of resistance to these fungicides, we cloned and sequenced the mutant os-1 genes that encode putative osmo-sensing histidine kinase. Within the os-1 gene product (Os1p), the type I strains, NM233t and Y256M209, carried a stop codon at amino acid position 308 and a frameshift at amino acid position 294, respectively. These mutation sites were located on the upstream of histidine kinase and the response regulator domains of Os1p, strongly suggesting that type I strains are null mutants. The null mutants, NM233t and Y256M209, were highly resistant to iprodione and fludioxonil; thus Os1p is essential for these fungicides to express their antifungal activity. The amino acid changes in Os1p, 625Pro from Leu, 578Val from Ala, and 580Arg from Gly were found in the type II strains, M16, M155-1 and P5990, respectively. Os1p is novel in having six tandem repeats of 90 amino acids in the N terminal. Each amino acid change of the type II strains was located on the fifth unit of six tandem repeats. Type II strains with single amino acid changes were more sensitive to osmotic stress than the null mutants (type I), indicating that the amino acid repeats of Os1p were responsible for an important function in osmo-regulation.     

Intratubal insemination with fresh semen in dogs

The number of spermatozoa required to obtain conception by intratubal insemination in dogs was examined. Three groups consisting of 5, 8 and 8 dogs received 0.5 x 10 (6), 2.0 x 10(6) and 4.0 x 10(6) spermatozoa, respectively, into each uterine tube. No conception occurred in the 5 animals inseminated with 0.5 x 10(6) spermatozoa, but conception occurred in 6/8 (75.0%) and 3/8 (37.5%) dogs inseminated with 2.0 x 10(6) and 4.0 x 10 (6) spermatozoa, respectively. Among the pregnant animals, three aborted (33.3%) and the mean number of newborns was small, 2.5 +/- 0.5 (SE). One acardiacus anceps was observed with normal fetus in one animal with a Caesarean delivery.     

Lectin-binding characteristics and capacitation of canine epididymal spermatozoa

Cross sections of the testes and the caput, corpus and cauda epididymides removed from 12 dogs were stamped on glass slides, and the sperm on the slides were stained with 6 different FITC-lectins (Con A, DBA, PNA, PSA, SBA, and WGA) to examine the characteristics of the surface glycoproteins (GPs) on canine epididymal sperm. The corpus epididymal sperm were washed three times by centrifugation, and their lectin-binding characteristics were investigated. The washed sperm from the corpus and cauda epididymides were incubated for 24 hr, and the fertilizing capacity of the sperm was evaluated by calculating the percentages of actively motile sperm (%MO), hyperactivated sperm (%HA), and acrosome-reacted sperm (%AR), and the number of canine zona-pellucida (ZP)-binding sperm. The testicular sperm did not stain with SBA lectin, but the SBA lectin fluorescence was observed on the surface of the entire heads of the caput epididymal sperm. Although all of the entire heads or acrosomal regions of the corpus epididymal sperm stained with all 6 FITC-lectins, the heads and acrosomal regions of the cauda epididymal sperm did not stain with DBA or SBA lectins. Washing the sperm from the corpus epididymis resulted in loss of the fluorescence of the FITC-DBA and -SBA lectins. The mean %MO, %HA, %AR, and ZP-binding number of the cauda epididymal sperm after 24 hr of incubation were higher than the values for the corpus epididymal sperm. All of the mean values for the washed sperm from the corpus and cauda epididymides were higher than the values for the unwashed sperm from the corpus and cauda, and with the exception of %AR, the values from the washed sperm from the corpus epididymis were significantly higher (P<0.05, 0.01). The results indicate that DBA- and SBA-lectin-binding GPs on the surface of canine epididymal sperm are associated with the fertilizing capacity and may be decapacitation factors.     

Factors affecting transuterine migration of canine embryos

Dogs, cats, and pigs have a bicornuate uterus, and transuterine migration of embryos occurs in 40% or more of pregnant animals. However, the mechanism of the transuterine migration has not been elucidated in dogs. Thus, we investigated the occurrence of transuterine migration of embryos when embryos were retained in an unilateral uterine tube with more ovulated ova (Experiment 1), when one ovary was excised (Experiment 2), and when ova ovulated from the right and left ovaries were fertilized with sperm from male dogs with different blood types (Experiment 3). Transuterine migration of embryos was observed in 7/8 (87.5%), 10/10 (100%), and 11/17 (67.4%) fertilized animals in Experiments 1, 2, and 3, respectively. In Experiment 3, intrauterine embryo mixing reported in pigs did not occur. These findings suggest that transuterine migration of embryos occurs due to the number of embryos that enter the uterus but that differences in the number of ovulated ova between the right and left ovaries or the number of embryos retained in the uterine tube do not affect the migration.     

Performance of using opposing homozygotes for paternity testing in Japanese Black cattle

Genome-wide single nucleotide polymorphism (SNP) markers in Japanese Black cattle enable genomic prediction and verifying parent–offspring relationships. We assessed the performance of opposing homozygotes (OH) for paternity testing in Japanese Black cattle, using SNP genotype information of 50 sires and 3,420 fattened animals, 1,945 of which were fathered by the 50 genotyped sires. The number of OH was counted for each sire–progeny pair in 28,764 SNPs with minor allele frequencies of ≥0.05 in this population. Across all pairs of animals, the number of OH tended to increase as the pedigree-based coefficient of relationship decreased. With a threshold of 288 (1% of SNPs) for paternity testing, most sire–progeny pairs were detected as true relationships. The frequency of Mendelian inconsistencies was 2.4%, reflecting the high accuracy of pedigree information in Japanese Black cattle population. The results indicate the utility of OH for paternity testing in Japanese Black cattle.     

Effects of acorn attack by curculio weevils on the germination and early growth of <Emphasis Type="Italic">Pasania edulis</Emphasis> (Makino) seedlings

We conducted field studies to evaluate the impact that curculio weevil attacks on Pasania edulis (Fagacea) acorns have on the regeneration of this tree. The germination ratio of weevil-attacked acorns was significantly lower than that of sound acorns. The number and position of the attacks on acorns affected the germination ratio. The seedlings from weevil-attacked acorns were shorter and had a smaller leaf area than those from sound acorns. The negative effects on seedling height lasted for at least three years after germination. We also studied the handling of the two types of acorns by granivorous Apodemus mice in a broad-leaved forest dominated by P. edulis. The mice picked up, transported, hoarded, and recovered sound and weevil-attacked acorns similarly. In the study site, the seedlings from weevil-attacked acorns were estimated to account for 1.5–20.4 % of the total seedlings for cohorts of mast years and 0–3.7 % for those of poor or medium acorn production. From these results, we conclude that acorns with the lower part of their cotyledons slightly damaged by weevil larvae might still be able to contribute to the regeneration of P. edulis in the field but that their contribution would be negligible or small even in mast years in this study site.     

Continuum contraction of tension wood fiber induced by repetitive hygrothermal treatment

Wood Science and Technology - Tension wood, when kiln-dried, is likely to deform hugely, which is probably caused by a gelatinous layer of the gelatinous fiber. To elucidate the mechanism behind...     

The therapeutic effects of SET/I2PP2A inhibitors on canine melanoma

Canine melanoma is one of the most important diseases in small animal medicine. Protein phosphatase 2A (PP2A), a well conserved serine/threonine phosphatase, plays a critical role as a tumor suppressor. SET/I2PP2A is an endogenous inhibitor for PP2A, which directly binds to PP2A and suppresses its phosphatase activity. Elevated SET protein levels have been reported to exacerbate human tumor progression. The role of SET in canine melanoma, however, has not been understood. Here, we investigated the potential therapeutic role for SET inhibitors in canine melanoma. The expression of SET protein was observed in 6 canine melanoma cell lines. We used CMeC-1 cells (primary origin) and CMeC-2 cells (metastatic origin) to generate cell lines stably expressing SET-targeting shRNAs. Knockdown of SET expression in CMeC-2, but not in CMeC-1, leads to decreased cell proliferation, invasion and colony formation. Phosphorylation level of p70 S6 kinase was decreased by SET knockdown in CMeC-2, suggesting the involvement of mTOR (mammalian target of rapamycin)/p70 S6 kinase signaling. The SET inhibitors, OP449 and FTY720, more effectively killed CMeC-2 than CMeC-1. We observed PP2A activation in CMeC-2 treated with OP449 and FTY720. These results demonstrated the potential therapeutic application of SET inhibitors for canine melanoma.     

Ligand-binding characteristics of feline insulin-binding immunoglobulin G

Polyclonal immunoglobulin (Ig) G autoantibodies against insulin have been identified in sera of healthy cats. We purified and fractionated insulin-binding IgGs from cat sera by affinity chromatography and analyzed affinity of insulin-binding IgGs for insulin and their epitopes. Following the passing of fraction A, which did not bind to insulin, insulin-binding IgGs were eluted into two fractions, B and C, by affinity chromatography using a column fixed with bovine insulin. Dissociation constant (KD) values between insulin-binding IgGs and insulin, determined by surface plasmon resonance analysis (Biacore™system), were 1.64e⁻⁴ M for fraction B (low affinity IgGs) and 2e⁻⁵ M for fraction C (high affinity IgGs). Epitope analysis was conducted using 16 peptide fragments synthesized in concord with the amino acid sequence of feline insulin by an enzyme-linked immunosorbent assay. Fractions B and C showed higher absorbance (affinity) of the peptide fragment of 10 amino acid residues at the carboxyl-terminal of the B chain (peptide No. 19), followed by peptide fragments of 6 to 15 amino acid residues of the B chain (peptide No. 8). Fraction C showed a higher absorbance to 7 to 16 amino acid residues of the B chain (peptide No. 5) compared with the absorbance of fraction B. Polyclonal insulin-binding IgGs may form a macromolecule complex with insulin through the multiple affinity sites of IgG molecules. Feline insulin-binding IgGs are multifocal and may be composed of multiple IgG components and insulin.