The primary aim of the present study was to investigate the overexpression of the rice (Oryza sativa L.) programmed cell death 5 (OsPDCD5) gene in rice plant. Constitutive expression of OsPDCD5 from the cauliflower mosaic virus (CaMV) 35S promoter induced programmed cell death (PCD) in transgenic rice. Programmed cell death was accompanied by typical features, including inhibition of developmental growth, a reduction of fresh weight, degradation of total protein content, and fragmentation of genomic DNA. These results suggest that OsPDCD5 plays an essential role in the regulation of PCD in rice plants.
In eukaryotic cells, the origin recognition complex (ORC) governs the initiation site of DNA replication and formation of the prereplication complex. The isolation, characterization and tissue-specific expression of a putative ORC subunit 2 (OsORC2) in Oryza sativa is described here. A novel cDNA fragment encoding rice ORC2 was isolated by screening the subtractive library, which had a higher expression level in inflorescence meristem than in shoot apical meristem. The full-length cDNA of rice ORC2 was obtained by the method of rapid amplification of cDNA ends, which contained an 1140 bp open reading frame encoding a 379 amino acid polypeptide. Sequence alignment shows that there is a high homology between the deduced amino sequence of OsORC2 and maize ORC2 (85%). The tissue-specific expression pattern of OsORC2 reveals that it is abundant in roots, seedling and inflorescence meristem, while its expression level is much lower in mature leaves and shoot.
Feeding and exhaustive exercise are known to elevate metabolism. However, acid-base status may be oppositely affected by the two processes. In this study, we first investigated the acid-base response of Chinese catfish to feeding (the meal size was about 8% of body mass) to test whether an alkaline tide (a metabolic alkalosis created by gastric HCl secretion after feeding) would occur. We then determined the combined effects of feeding and exhaustive exercise on excess post-exercise oxygen consumption and acid-base status to determine whether the alkaline tide induced by feeding protects against acid-base disturbance during exhaustive exercise and affects subsequent recovery. Arterial blood pH increased from 7.74 +/- 0.02 before feeding to 7.88 +/- 0.02 and plasma [HCO(3)(-)](pl) increased from 5.42 +/- 0.29 to 7.83 +/- 0.37 mmol L(-1) 6 h after feeding, while feeding had no significant effect on PCO2. Exhaustive exercise led to a significant reduction in pH by 0.46 units and a reduction of [HCO(3)(-)](pl) by approximately 3 mmol L(-1). Lactate concentrations in white muscle and plasma increased by 2.4 mmol L(-1) and 13.4 micromol g(-1), respectively. Fed fish had a higher pH and [HCO(3)(-)](pl) than fasting fish at rest, and the reductions in pH (0.36 units) and [HCO(3)(-)](pl) (approximately 2 mmol L(-1)) were thus lower after exhaustive exercise. However, the recovery of acid-base status and metabolites were similar in digesting and fasting fish. Overall, a significant alkaline tide was found in Chinese catfish after feeding. The alkaline tide elicited by feeding significantly prevented the decreases in pH and [HCO(3)(-)](pl) immediately after exhaustive exercise, but recovery from exhaustive exercise was not affected by digestion.
The primary aim of the present study was to investigate the overexpression of the rice (Oryza sativa L. subsp. japonica var. Zhonghua 11) flowering control gene (rFCA-RRM2) in monocotyledonous model rice. Constitutive expression of rFCA-RRM2 from the Act1-5 rice promoter caused late flowering in transgenic rice and increased grain weight that was more than 50% higher than that of control plants, which is the first demonstration of rFCA-RRM2 being able to increase rice production. Late flowering was accompanied by strong phenotype and some morphological modifications. These observations suggest that rFCA-RRM2 is a useful tool for phenotype improvement and yield enhancement in cereal crops.
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