Use of genomic recursions and algorithm for proven and young animals for single‐step genomic BLUP analyses – a simulation study

The purpose of this study was to examine accuracy of genomic selection via single‐step genomic BLUP (ssGBLUP) when the direct inverse of the genomic relationship matrix ( G ) is replaced by an approximation of G ^?1 based on recursions for young genotyped animals conditioned on a subset of proven animals, termed algorithm for proven and young animals (APY). With the efficient implementation, this algorithm has a cubic cost with proven animals and linear with young animals. Ten duplicate data sets mimicking a dairy cattle population were simulated. In a first scenario, genomic information for 20k genotyped bulls, divided in 7k proven and 13k young bulls, was generated for each replicate. In a second scenario, 5k genotyped cows with phenotypes were included in the analysis as young animals. Accuracies (average for the 10 replicates) in regular EBV were 0.72 and 0.34 for proven and young animals, respectively. When genomic information was included, they increased to 0.75 and 0.50. No differences between genomic EBV (GEBV) obtained with the regular G ^?1 and the approximated G ^?1 via the recursive method were observed. In the second scenario, accuracies in GEBV (0.76, 0.51 and 0.59 for proven bulls, young males and young females, respectively) were also higher than those in EBV (0.72, 0.35 and 0.49). Again, no differences between GEBV with regular G ^?1 and with recursions were observed. With the recursive algorithm, the number of iterations to achieve convergence was reduced from 227 to 206 in the first scenario and from 232 to 209 in the second scenario. Cows can be treated as young animals in APY without reducing the accuracy. The proposed algorithm can be implemented to reduce computing costs and to overcome current limitations on the number of genotyped animals in the ssGBLUP method.     

Undulated flooring in the rearing tank decreases hypermelanosis in Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis>

In the aquaculture of the Japanese flounder Paralichthys olivaceus, hypermelanosis, a malpigmentation condition in which the scales of a significant area on the blind side express the characteristics of those on the ocular side, remains a major concern. Since introducing sand into the rearing tank effectively suppresses hypermelanosis, the inhibitory effects of various characteristics of the surface of the tank floor were investigated. Although an inhibitory effect was observed in both tanks with a sand-image floor and a sand-pasted floor, the strongest effect was found in tanks with a dimpled floor. In addition, covering the inner surface of the tank with net also inhibited hypermelanosis. Using a commercially available corrugated plate, the inhibition of hypermelanosis was confirmed with a noted increase in this effect when combined with light coloration. Juveniles tended to situate themselves in the valley portions of the corrugated plate, suggesting that floor contact with the blind side may contribute to hypermelanosis inhibition. Further observations on the floor contact area with various floor configurations suggested that hypermelanosis is locally suppressed in the areas with floor contact. Therefore, suppression by an undulated (both dimpled and corrugated) floor is likely due to an increase in floor contact area with the blind side.     

Juveniles of threadsail filefish, <Emphasis Type="Italic">Stephanolepis cirrhifer</Emphasis>, can survive and grow by feeding on moon jellyfish <Emphasis Type="Italic">Aurelia aurita</Emphasis>

We conducted feeding experiments on threadsail filefish Stephanolepis cirrhifer juveniles for 16 days to evaluate the efficacy of moon jellyfish Aurelia aurita as a prey item. Four treatments, each with 40 individuals, were prepared to compare fish growth performance. The treatments consisted of filefish that were starved (control) (S), fed only jellyfish (J), fed only krill (K), and fed both jellyfish and krill (JK). Fish in the S treatment exhibited a 50% mortality rate and reduced body weight, whereas the J treatment exhibited a zero mortality rate and increased body weight. Fish in the JK treatments showed a significantly faster growth than those in the K treatment. Filefish consumed as much as 24 and 13 times their own body weight in jellyfish per day in the J and JK treatments, respectively. This is the first report showing that growth can be sustained by feeding a marine fish only jellyfish, and indicates the potential of jellyfish as a fish prey in both nature and captivity.     

Identification of oyster-derived hypotensive peptide acting as angiotensin-I-converting enzyme inhibitor

Angiotensin-I-converting enzyme (ACE) plays a crucial role in the crisis of hypertension. Some peptides that originate from protease hydrolysates are known to suppress ACE activity in vitro and in vivo. Here, we investigated whether trypsin hydrolysate of oyster Crassostrea gigas showed hypotensive activity and ACE inhibition. The hydrolysate significantly suppressed systolic blood pressure and ACE activity in spontaneously hypertensive rats following a one-shot oral administration and a long-term feeding experiment lasting 9 weeks. Each hydrolysate from oyster tissue showed ACE inhibitory activity, indicating the hypotensive effect was due to synergism. One potent ACE inhibitory peptide, Asp-Leu-Thr-Asp-Tyr, was identified from the hydrolysate of the striate muscle, and the peptide exhibited hypotensive activity in vivo. Protease digestion analysis suggested that Asp-Tyr could be the real effector of this penta-peptide in vivo.     

Effect of pH on the thermal stability of potent roasty odorants, 3-mercapto-3-methylbutyl esters, in coffee drink

The effect of pH on the thermal stability of potent roasty odorants, 3-mercapto-3-methylbutyl esters, in coffee drinks was investigated. The concentration of 3-mercapto-3-methylbutyl formate in the coffee drink was drastically decreased during the heat processing. However, the residual ratio of this compound in the coffee drink adjusted to pH 5.0 was higher than that of pH 6.5. On the other hand, the residual ratios of 3-mercapto-3-methylbutyl acetate showed high values in the coffee drinks adjusted to both pHs. In the pH range of 3-7, the residual ratios of 3-mercapto-3-methylbutyl formate in aqueous model solutions varied depending on the pH value. It had a thermal stability maximum at pH 4.0, while 3-mercapto-3-methylbutyl acetate showed stability during heat processing over all the pH values tested. In addition, the residual ratios of the formate and acetate esters, which were composed of various alcohol derivatives, showed the same tendency as that of the 3-mercapto-3-methylbutyl esters. These results suggested that the low thermal stability and pH dependence of 3-mercapto-3-methylbutyl formate are based on the structure of the formate ester.     

Formation mechanism of p-methylacetophenone from citral via a tert-alkoxy radical intermediate

The aim of this study was to clarify the formation mechanism of a potent off-odorant, p-methylacetophenone, from citral under acidic aqueous conditions. An acidic aqueous solution (pH 3.0) containing 10 mg/L of citral was stored at 40 degrees C for 2 weeks. Among the compounds detected in the stored citral solution, 4-(2-hydroxy-2-propyl)benzaldehyde was identified for the first time as a degradation product from citral. The formation of p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde behaved the same when antioxidants were added to the citral solution. In addition, both compounds were formed by the Fe(2+)-induced decomposition of 8-hydroperoxy-p-cymene, another compound identified in the stored citral solution. These results suggested that both p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde can be formed via the same radical intermediate [p-CH3C6H4C(CH3)2O*] that can be derived from the O-O bond homolysis of 8-hydroperoxy-p-cymene. On the other hand, the degradation of 8-hydroperoxy-p-cymene without Fe2+ under acidic aqueous conditions did not yield p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde, but the degradation of citral without Fe2+ did. Therefore, other than the decomposition of 8-hydroperoxy-p-cymene, a mechanism to generate the tert-alkoxy radical intermediate was proposed for the formation of p-methylacetophenone and 4-(2-hydroxy-2-propyl)benzaldehyde in the citral solution.     

Identification of geranic acid, a tyrosinase inhibitor in lemongrass (Cymbopogon citratus)

Lemongrass is a popular Asian herb having a lemon-like flavor. Very recently, potent tyrosinase inhibitory activity has been found in lemongrass in addition to various biological activities reported in the literature. The aim of the present study is to identify the active compounds in the lemongrass. An assay-guided purification revealed that one of the active substances was geranic acid. Geranic acid has two stereoisomers, which are responsible for the trans and cis geometry on the conjugated double bond. Both isomers are present in the active ethyl acetate-soluble extract of the lemongrass, and their IC50 values were calculated to be 0.14 and 2.3 mM, respectively. The structure requirement of geranic acid for the potent tyrosinase inhibitory activity was investigated using geranic acid-related compounds.     

Identification of odor-active 3-mercapto-3-methylbutyl acetate in volatile fraction of roasted coffee brew isolated by steam distillation under reduced pressure

In a roasted Arabica coffee brew, the potent roasty odor quality compound was identified as 3-mercapto-3-methylbutyl acetate by comparison of its Kovats gas chromatography retention index, mass spectrum, and odor quality to those of the synthetic authentic compound. 3-Mercapto-3-methylbutyl acetate has been identified for the first time in the coffee, and according to the results of the aroma extract dilution analysis, the contribution of this compound to the flavor of the roasted coffee brew varied depending on the degree of the coffee bean roasting. The concentration of this compound in the coffee brews as with 3-mercapto-3-methylbutyl formate increased with an increase in the degree of roasting. However, the slope of the amount of both esters was different, and 3-mercapto-3-methylbutyl acetate hardly increased with a low degree of roasting at more than a 21 luminosity (L)-value, but it rapidly increased when the roasting degree of the coffee beans reached the L-value of 18. These results suggested that the contribution of 3-mercapto-3-methylbutyl acetate to the overall flavor is peculiar to the flavor of the highly roasted coffee.     

Characterization of epoxydecenal isomers as potent odorants in black tea (Dimbula) infusion

In a black tea (Dimbula) infusion, the potent "sweet and/or juicy" odorants were identified as the cis- and trans-4,5-epoxy-(E)-2-decenals by comparison of their gas chromatography retention indices, mass spectra, and odor quality to those of the actual synthetic compounds. Of the two odorants, cis-4,5-epoxy-(E)-2-decenal has been identified for the first time in the black tea. On the basis of the aroma extract dilution analysis on the flavor distillate obtained using the solvent-assisted flavor evaporation technique from the black tea infusion, these isomers showed higher flavor dilution (FD) factors. The FD factors and concentrations of these odorants in the black tea infusion were observed to be much higher than those from Japanese green tea. In addition, the model studies showed that these odorants were generated from linoleic acid and its hydroperoxides by heating, but the generated amounts of these odorants from linoleic acid were much less than those of its hydroperoxides. It can be assumed from these results that the withering and fermentation, which are characteristic processes during the manufacturing of the black tea, which includes the enzymatic reaction such as lipoxygenase, is one of the most important factors for the formation of the epoxydecenal isomers.