寒地水稻生长发育动态研究初探

以黑龙江省主栽的两个水稻品种为试验材料,通过调查试验材料的生育期、干物质积累、叶面积变化和分蘖消长动态的测定,明确了拔节至抽穗期是水稻产量形成的关键时期;根据试验材料干物质积累的变化规律建立了干物质随时间变化的生长曲线,经检验拟合较好。     

Effects of exogenous application of proline and betaine on the growth of tobacco cultured cells under saline conditions

The effects of the application of exogenous proline and betaine on the growth of tobacco cultured cells subjected to salt stress were investigated. Both proline and betaine mitigated the inhibition of growth of tobacco cells under saline conditions, but the harmful effect of salinity was less reduced by betaine than by proline. The amount of intracellular betaine in tobacco cells cultured in the NaCI medium supplemented with 20 mm betaine was larger than that of intracellular proline in the NaCI medium with 20 mm proline. The 1,1-diphenyl2-picrylhydrazyl (DPPH) experiments showed that proline displayed an antioxidant activity and that the antioxidant activity of betaine was not detectable. The malondialdehyde (MDA) assay demonstrated that exogenous proline but not betaine decreased the amount of MDA in salt-stressed tobacco cells. These results suggest that the difference in the mitigation effects between proline and betaine may be responsible for the difference in the antioxidant activity.     

Antidiabetic activities of chalcones isolated from a Japanese Herb, Angelica keiskei

Diabetes mellitus is a chronic disease that is characterized by hyperglycemia caused by insufficient insulin action. We have explored the edible ingredients from folk medicines in Japan that contain substances complementing insulin action, such as the induction of adipocyte differentiation and the enhancement of glucose uptake. We eventually found that the ethanol extract from a Japanese herb "Ashitaba", Angelica keiskei, contained two major chalcones of 4-hydroxyderricin (4-HD) and xanthoangelol that showed strong insulin-like activities via a pathway independent of the peroxisome proliferator-activated receptor-gamma activation. The 4-HD especially showed the preventive effects on the progression of diabetes in genetically diabetic KK-Ay mice.     

Effects of the fattening period on the fatty acid composition of fat deposits and free amino acid and inosinic acid contents of the longissimus muscle in carcasses of Japanese Black steers

The effects of the fattening period on carcass characteristics, fatty acid composition of fat deposits, and muscle free amino acid (FAA) and inosinic acid (IMP) contents were evaluated in Japanese Black steers. Ten castrated, 10-month-old calves derived from the same sire were divided into five to be slaughtered at the age of 30 months after a 20-month fattening period (20-month group) and five to be slaughtered at the age of 34 months after a 24-month fattening period (24-month group). Concerning the fatty acid composition of subcutaneous fat, the percentage of palmitoleic acid was higher ( P  < 0.05) in the 24- than in the 20-month group, but no difference was noted in any other fatty acids. For intermuscular fat, no difference was observed in any fatty acids. The percentages of oleic acid and total monounsaturated fatty acid of intramuscular and perinephric fat were higher ( P  < 0.05) in the 24- than in the 20-month group. Of the FAAs in the longissimus thoracis muscle, the threonine and tyrosine contents were lower ( P  < 0.05) in the 24- than in the 20-month group. The IMP content was higher ( P  < 0.05) in the 24- than in the 20-month group, suggesting an effect of prolongation of the fattening period.     

Geographical distribution of ribosomal DNA variation in taro, Colocasia esculenta (L.) Schott, in eastern Asia

Restriction fragment length polymorphism (RFLP) at the ribosomal RNA gene loci (rDNA) was investigated in 227 accessions of taro, Colocasia esculenta (L.) Schott, from China, Japan, Taiwan, and Vietnam. Eighteen different restriction fragment patterns of rDNA were observed. The results were largely consistent with a previous classification based on isozyme data. Some rDNA patterns were distributed extensively in the temperate zone from inland China to Japan. On the other hand, some other patterns ranged in coastal and/or insular areas from the tropical zone to the temperate zone (Japan). These geographical distributions may suggest two different routes for the introduction of taro into Japan: one from China,and the other most likely from Southeast Asia, via Taiwan and the Ryukyu Islands (southern Japan). This revised version was published online in August 2006 with corrections to the Cover Date.     

Quantitative trait loci for whiteness of cooked rice detected in improved rice cultivars in Hokkaido

Improving the eating quality of cooked rice has been one of the most important objectives in rice breeding programs. Eating quality of cooked rice is a complex trait including several components, such as external appearance, taste, aroma, and texture. Therefore, dissection of these components followed by marker-assisted selection of detected QTL(s) may be a useful approach for achieving desirable eating quality in rice breeding. Whiteness of cooked rice (WCR) is an important factor related to the external appearance of cooked rice. WCR is known to be associated with the amylose and protein contents of the endosperm. However, the genetic basis of WCR remains unclear. In this study, we evaluated phenotypic variation in WCR among recently developed rice cultivars from Hokkaido, Japan. Then, we developed doubled haploid lines (DHLs) derived from a cross between two cultivars from Hokkaido, Joiku No. 462 (high WCR) and Jokei06214 (low WCR). Using the DHLs, we detected two QTLs for WCR, qWCR3 and qWCR11, on chromosomes 3 and 11, respectively. We also examined the dosage effect of the two QTLs based on both the categorized segregants in the DHLs and the relationship between the WCR phenotype and inheritance around the QTL regions in cultivars from Hokkaido.     

Absorption and bioavailability of artepillin C in rats after oral administration

Artepillin C (AC), an active ingredient of Brazilian propolis, permeates intact across Caco-2 cells by transcellular passive diffusion. The permeation of AC across Caco-2 cells is as efficient as that of phenolic acids and the microbial metabolites of poorly absorbed polyphenols, which are actively absorbed by the monocarboxylic acid transporter (MCT) (Biochim. Biophys. Acta 2005, 1713, 138-144). Here, the absorption of orally administered AC in rats has been studied to evaluate its pharmacokinetics and bioavailability in vivo in comparison with those of p-coumaric acid (CA), a substrate of MCT. Rats were given 100 micromol/kg of body weight of AC or CA, and blood was subsequently collected from the portal vein and abdominal artery. AC, CA, and their metabolites were quantified by coulometric detection using HPLC-ECD. The serum concentration of intact AC and CA in the portal vein peaked at 5-10 min after administration, with a C(max) of 19.7 micromol/L for AC and 74.8 micromol/L for CA. The area under the curve (AUC) for intact AC and CA in the portal vein was calculated from the serum concentration as 182.6 and 3057.3 micromol.min.L(-1), respectively. The absorption efficiency of CA was about 17-fold higher than that of AC. Furthermore, the bioavailability of CA was about 278-fold higher than that of AC, and the ratio of AUC in the abdominal artery to AUC in the portal vein was 0.04 and 0.70, for AC and CA, respectively. Thus, AC is likely to be more susceptible to hepatic elimination than is CA. The bioactive compound of AC in vivo should be investigated further.     

Deodorization of soybean proteins by enzymatic and physicochemical treatments

To utilize soy protein isolate (SPI) more widely, a convenient and effective method for deodorizing it is required. This paper reports a new deodorizing method using various types of solid adsorbents made of polystyrene, polymethacrylate, and zeolite, as well as charcoal. Treatment of the SPI solution with them decreased the hexanal content in the solution, whereas the content of linoleic acid was not much decreased. A brominated polystyrene adsorbent (SEPABEADS SP207) and a zeolite adsorbent (HSZ-360HUD) removed hexanal most effectively, although 30-40% of the total hexanal remained. A model experiment showed that their hexanal adsorption capacity was much higher than the hexanal content in the SPI solution and that an excess amount of hexanal added to the SPI solution was mostly removed by them. These results suggest that hexanal in the SPI solution can be classified into two types. Hexanal of type I may be free or bound weakly on the surface of proteins and is removable by the adsorbents, whereas hexanal of type II may be bound tightly inside proteins and is unremovable by the adsorbents. Despite the considerable amount of hexanal remaining in the SPI solution even in the most successful cases, the SPI solution was well deodorized as shown by the sensory test. Accordingly, type I hexanal may be closely related to the soybean odor. Removal of hexanal by the adsorbents was not much improved by alpha-chymotryptic digestion of SPI. Type II hexanal might be in similar states even in the chymotryptic digests.     

Coagulation of soy protein isolates induced by subtilisin Carlsberg

The coagulation of soy protein isolates (SPI) induced by subtilisin Carlsberg was studied. The proteins were digested to fragments of 16 kDa or less in the early stage of the reaction, followed by coagulation. The time-course of the coagulation measured by turbidity was separated into three phases. The turbidity decreased from the initial level observed at time zero to the minimum level (OD1) at time T1 (15-20 min) in the first phase. Then, it increased drastically to reach the maximum (OD2) at time T2 (60-70 min) in the second phase, which was followed by a slight decrease in the third phase. The coagulation was terminated at T2, where 30-35% of the weight of the SPI proteins was in coagula. Proteins in the coagula were degraded slowly in the prolonged incubation, and the protein content in the coagula was finally 15-20% of the weight. The time-course of the turbidity agreed well with that of the weight of the precipitates formed, indicating that the turbidity reflects the progress of the coagulation. The turbidity change (OD1 to OD2) from the start to the end of the coagulation increased proportionally to the SPI concentration (4.9-11 mg/mL), although the time (T1 to T2) needed for the coagulation was independent of the concentration. The growth of the coagula is promoted by increasing the SPI concentration and is rate-limiting in the coagulation.