Enzymatic synthesis of gamma-glutamylvaline to improve the bitter taste of valine

The taste of several bitter amino acids is reduced, sourness produced, and preference increased by gamma-glutamylization. An enzymatic method for synthesizing gamma-Glu-Val involving bacterial gamma-glutamyltranspeptidase (GGT) was developed. The optimum reaction conditions for the synthesis of gamma-Glu-Val were 20 mM Gln, 300 mM Val, and 0.04 U/ml GGT, pH 10. After 3-hr incubation at 37 degrees C, 17.6 mM gamma-Glu-Val was obtained, with the yield being 88%. gamma-Glu-Val was purified on a Dowex 1 x 8 column and then identified by NMR.     

New neurons follow the flow of cerebrospinal fluid in the adult brain

In the adult brain, neuroblasts born in the subventricular zone migrate from the walls of the lateral ventricles to the olfactory bulb. How do these cells orient over such a long distance and through complex territories? Here we show that neuroblast migration parallels cerebrospinal fluid (CSF) flow. Beating of ependymal cilia is required for normal CSF flow, concentration gradient formation of CSF guidance molecules, and directional migration of neuroblasts. Results suggest that polarized epithelial cells contribute important vectorial information for guidance of young, migrating neurons.     

Loss of imprinting of Igf2 alters intestinal maturation and tumorigenesis in mice

Loss of imprinting (LOI) of the insulin-like growth factor II gene (IGF2) is an epigenetic alteration that results in a modest increase in IGF2 expression, and it is present in the normal colonic mucosa of about 30% of patients with colorectal cancer. To investigate its role in intestinal tumorigenesis, we created a mouse model of Igf2 LOI by crossing female H19+/- mice with male Apc+/Min mice. Mice with LOI developed twice as many intestinal tumors as did control littermates. Notably, these mice also showed a shift toward a less differentiated normal intestinal epithelium, reflected by an increase in crypt length and increased staining with progenitor cell markers. A similar shift in differentiation was seen in the normal colonic mucosa of humans with LOI. Thus, altered maturation of nonneoplastic tissue may be one mechanism by which epigenetic changes affect cancer risk.     

甲烷气体产生量与牧草营养参数的相关性分析

为分析野生牧草的营养参数与甲烷气体产生量之间的相关性,采集内蒙古山羊喜食的4科31种处于生长旺盛期野生牧草测定营养参数,以上述牧草为底物,进行体外发酵并测定甲烷气体产生量.体外培养条件下牧草的甲烷气体产生量与牧草中的粗蛋白(CP)、干物质消失率(IVDMR)含量呈正相关,与中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量呈负相关,与无氮浸出物(NFE)含量相关性表现不一致;体外培养条件下4科牧草的甲烷气体产生量的预测模型为Y=5.962+O.107CP+O.035NDF-0.135ADF+0.(NONFE+0.001IVDMR(R=O.767,P<0.001).     

Greenhouse gases emission from paddy soil during the fallow season with and without winter flooding in central Japan

Many papers on measurements of greenhouse gases (GHGs) emission in rice paddies during a rice cropping season have been published. During a non-cropping season between Nov. and Apr., we investigated direct and indirect GHGs emissions in rice paddies. The indirect GHGs emission was evaluated as the amount of dissolved gases leaching from the paddy fields. Water management practices for the experiment were (1) continuous flooding (CF) and (2) non-flooding (NF). Although the direct CO₂ emission in the CF treatment was remained nearly zero during the non-cropping period, direct CO₂ emission in the NF treatment was continuously observed throughout the non-cropping period. The concentration of dissolved N₂O in the NF treatment was below the detection limit of the instrument during the non-cropping period except immediately after the flooding and before the drainage. The concentration of dissolved N₂O kept approximately 2 µg L^?1 during the non-cropping period in the CF treatment. The direct CH₄ emission and dissolved CH₄ were not observed during the non-cropping period. Total gas emission in the NF treatment was 10 times as large as that in the CF treatment. Direct CO₂ emission accounted for more than 90 % of the total emission in both treatments.     

Genetically structured population and demographic history of the goldlined spinefoot <Emphasis Type="Italic">Siganus guttatus</Emphasis> in the northwestern Pacific

Sequence variation of the mitochondrial DNA was analyzed to examine the genetic structure and demographic history of the goldlined spinefoot Siganus guttatus in the northwestern Pacific. In total, 451 nucleotide sequences spanning from the tRNA^Thr gene to the middle of the control region were determined from 254 specimens collected from five localities; three in the Ryukyu Islands (Okinawa, Miyako, and Ishigaki Islands), Taiwan, and Cebu Island of the Philippines; 73 variable sites and 75 haplotypes were detected. Our results showed restricted gene flow and genetic differentiation among all populations, with the exception of genetic homogeneity between the Miyako and Ishigaki populations; that is, this species will be able to cross between Miyako and Ishigaki (ca. 120 km) by the transport of pelagic larvae, and gene flow between Okinawa and Miyako/Ishigaki Islands (ca. 330–450 km) is restricted. A non-dispersal strategy will lead to restricted gene flow and genetic structuring in S. guttatus. Both the neutrality tests and the mismatch distribution indicated that S. guttatus might have been in populations at demographic equilibrium. This suggests that population range expansion may have been restricted owing to a non-dispersal strategy that may have restrained S. guttatus from demographic expansion after glaciation. The result will be of fundamental importance for resource management of this species.     

Benzodiazepines inhibit the acetylcholine receptor-operated potassium current (IK.ACh) by different mechanisms in guinea-pig atrial myocytes

The anticholinergic effects of 7 benzodiazepines, bromazepam, camazepam, chlordiazepoxide, diazepam, lorazepam, medazepam and triazolam, were compared by examining their inhibitory effects on the acetylcholine receptor-operated potassium current (I(K).(ACh)) in guinea-pig atrial myocytes. All of these benzodiazepines (0.3-300 μM) inhibited carbachol (1 μM)-induced I(K).(ACh) in a concentration-dependent manner. The ascending order of IC(50) values for carbachol-induced I(K).(ACh) was as follows; medazepam, diazepam, camazepam, triazolam, bromazepam, lorazepam and chlordiazepoxide (>300 μM). The compounds, except for bromazepam, also inhibited I(K).(ACh) activated by an intracellular loading of 100 μM guanosine 5'-[γ-thio]triphosphate (GTPγS) in a concentration-dependent manner. The ascending order of IC(50) values for GTPγS-activated I(K).(ACh) was as follows; medazepam, diazepam, camazepam, lorazepam, triazolam chlordiazepoxide (>300 μM) and bromazepam (>300 μM). To clarify the molecular mechanism of the inhibition, IC(50) ratio, the ratio of IC(50) for GTPγS-activated I(K).(ACh) to carbachol-induced I(K).(ACh), was calculated. The IC(50) ratio for camazepam, diazepam, lorazepam, medazepam and triazolam was close to unity, while it for chlordiazepoxide could not be calculated. These compounds would act on the GTP binding protein and/or potassium channel to achieve the anticholinergic effects in atrial myocytes. In contrast, since the IC(50) ratio for bromazepam is presumably much higher than unity judging from the IC(50) values (104.0 ± 30.0 μM for carbachol-induced I(K).(ACh) and >300 μM for GTPγS-activated I(K).(ACh), it would act on the muscarinic receptor. In summary, benzodiazepines had the anticholinergic effects on atrial myocytes through inhibiting I(K).(ACh) by different molecular mechanisms.     

Brewer's yeast efficiently degrades phytate phosphorus in a corn-soybean meal diet during soaking treatment

Microbes such as yeast and Aspergillus are known to produce phytase, and Aspergillus phytase has been used as a feed additive for improving phytate-phosphorus bioavailability in monogastric animals. We measured phytase activity in some by-products from fermented food and beverage productions by yeast and Aspergillus . The phytase activity was as high as 3577 and 2225 PU/kg DM in raw and dried brewer's yeasts, respectively. On the other hand, the phytase activity was approximately 400 PU/kg DM in white-wine yeast and red-wine yeast. The phytase activity was further low in natto (fermented soybean) residue, soy sauce cake, rice brewer's grain and the activity was not detected in dried corn-barley distiller's grain with soluble and sweet-potato distiller's residue. The stability of phytase against pepsin was much lower in the brewer's yeast than in an Aspergillus phytase preparation. On the other hand, the addition of raw brewer's yeast effectively degraded phytate phosphorus in a corn-soybean meal diet during soaking. These results suggest that phytase in the examined by-products is not suitable for the phytase source of conventional diets, but that the soaking treatment with a raw brewer's yeast is an alternative method for improving phytate-phosphorus bioavailability in corn-soybean meal diets for pigs.     

Ribotyping of EntomopathogenicVerticittium lecanii in Japan

To estimate the genetic diversity in 30 isolates ofVerticillium lecanii from aphids, whiteflies, mite and black pine in Japan, including two commercialized strains (Mycotal and Vertalec), DNA polymorphisms in ribosomal DNA of those isolates were analyzed using polymerase chain reaction (PCR). The internal transcribed spacer (ITS) and intergenic spacer (IGS) regions of the nuclear ribosomal RNA gene of each isolate were analyzed by PCR-RFLP (restriction fragment length polymorphism). The size of the PCR product from the ITS region was ~ 580 bp in 27 of the isolates. A 600 bp ITS product was detected in Mycotal and Vertalec. One Japanese isolate produced both the 580 bp and 600 bp products. Enzymatic digestion of the ITS region with Sau3A I,Msp I,Hae III andRsa I revealed RFLPs that consisted of eight haplotypes. Mycotal and Vertalec were specific haplotypes that differed from other isolates. The Japanese isolates had a complex relationship with the original host, but we identified several specific haplotypes common to an aphid origin. Ten distinct IGS haplotypes were detected in the IGS region, some of which were associated with aphid and whitefly origins. These results suggest that the haplotype of rDNA RFLP analysis can be used for studying genetic diversity inV. lecanii.     

Effects of rumen‐protected methionine on milk production in early lactation dairy cattle fed with a diet containing 14.5% crude protein

We evaluated the influence on milk production of feeding early lactation cows a diet that included 14.5% crude protein (CP) and that did not meet methionine (Met) requirements or that met them by supplying rumen‐protected Met (RPMet). Thirty‐nine multiparous Holstein cows were allocated into two groups. For 15 weeks after calving, each group was fed one of the two total mixed rations, Control (n = 20) or Treatment (n = 19). The Treatment group received added RPMet at 0.034% (8 g/day) of the Control diet on dry matter basis. The adequacies of Met for the Control and Treatment groups were 96% and 106%, respectively, and for other amino acids, >110%. The CP level (14.5%) was 1 percentage point lower than that recommended by the Japanese Feeding Standard (2006). No between‐group differences were found in milk yield (40 kg/day), milk composition, plasma profile, rumen fermentation, nitrogen balance, or cow health. Met intake and the amount of rumen‐undegradable feed Met were higher in the Treatment group (p < 0.05). Microbial Met and total metabolizable Met did not differ between groups. Supplying RPMet in a 14.5% CP diet during early lactation did not dramatically affect milk production, because the amount of total metabolizable Met was unchanged.