Characterization of the endosperm starch and the pleiotropic effects of biosynthetic enzymes on their properties in novel mutant rice lines with high resistant starch and amylose content.

Resistant starch (RS) is beneficial to human health. In order to reduce the current prevalence of diabetes and obesity, several transgenic and mutant crops containing high RS content are being developed. RS content of steamed rice with starch-branching enzyme (BE)IIb-deficient mutant endosperms is considerably high. To understand the mechanisms of RS synthesis and to increase RS content, we developed novel mutant rice lines by introducing the gene encoding starch synthase (SS)IIa and/or granule-bound starch synthase (GBSS)I from an indica rice cultivar into a japonica rice-based BEIIb-deficient mutant line, be2b. Introduction of SSIIa from an indica rice cultivar produced higher levels of amylopectin chains with degree of polymerization (DP) 11-18 than those in be2b; the extent of the change was slight due to the shortage of donor chains for SSIIa (DP 6-12) owing to BEIIb deficiency. The introduction of GBSSI from an indica rice cultivar significantly increased amylose content (by approximately 10%) in the endosperm starch. RS content of the new mutant lines was the same as or slightly higher than that of the be2b parent line. The relationship linking starch structure, RS content, and starch biosynthetic enzymes in the new mutant lines has also been discussed.

Screening Method for Novel Rice Starch Mutant Lines Prepared by Introducing Gene Encoding Starch Synthase IIa and Granule-bound Starch Synthase I from Indica Cultivar into a Branching Enzyme IIb-Deficient Mutant Line.

The structure and properties of starch reserves in rice seeds are strongly affected by deficiencies in specific starch biosynthetic enzymes, which are highly expressed in storage tissues. Rice lines with unique seed starches should be utilized for food and industrial applications in the near future. We are currently developing novel rice mutant lines with distinct starch properties by introducing specific genes from different cultivars into mutant lines and by producing multiple combinations of single mutant lines. Obtaining the homozygous genotypes of the target genes is necessary during the screening process of these materials. In this study, we developed an effective, accurate screening method for identifying rice lines with novel starch composition. Specifically, we produced a novel mutant line in which we introduced genes encoding starch synthase IIa (SSIIa) and granule-bound starch synthase I (GBSSI) from indica cultivar into a starch branching enzyme IIb (BEIIb)-deficient mutant line.

Overexpression of interleukin 2 receptor, thymidine kinase and immunoglobulin-associated alpha-1 messenger RNA in a clinical case of enzootic bovine leukosis.

A 49-month-old Holstein cow with anorexia, tachypnea, enlarged peripheral lymph nodes, and difficulty standing up was suspected of bovine leukosis. Hematological examination revealed lymphocytosis with the presence of neoplastic cells. Increased total lactate dehydrogenase (LDH) activity, isozymes of LDH-2 and LDH-3 activities and thymidine kinase activity were observed. Cytological findings of fine needle aspiration of subiliac lymph nodes indicated lymphosarcoma. Histopathology and antibody analysis confirmed the diagnosis of enzootic bovine leukosis, a B-cell bovine lymphoma caused by bovine leukemia virus. Gene expressions known as biomarkers of hematopoietic neoplasia in human were also examined in the present case. Increased messenger RNA expression of interleukin 2 receptor, thymidine kinase, and immunoglobulin-associated alpha-1 was observed in the case animal.