8 research outputs found
Method using male sterility and a marker to produce hybrid seeds and plants
A method is provided for efficiently producing superior hybrid seed and plants. The method uses a genetic mechanism for ensuring high percentages of natural cross-pollination and combines this mechanism with a genetically conferred morphological trait that allows recognition of desirable genotypes at an early development stage. The genetic mechanism for ensuring high percentages of cross-pollination is male-sterile, a recessive genetic mutant. Thus, the method includes protocols for developing genetic male-sterile (ms) lines. The genetically conferred morphological trait that allows recognition of desirable genotypes at an early development stage is a seedling marker. Thus, the method includes protocols for developing genetic male-sterile (ms) lines with a seedling marker. In watermelon for example, the seedling marker can be a conditionally unfit mutant such as juvenile-albino (ja)
Central and Peripheral Administration of Secretin Inhibits Food Intake in Mice through the Activation of the Melanocortin System
Secretin (Sct) is released into the circulation postprandially from the duodenal S-cells. The major functions of Sct originated from the gastrointestinal system are to delay gastric emptying, stimulate fluid secretion from pancreas and liver, and hence optimize the digestion process. In recent years, Sct and its receptor (Sctr) have been identified in discrete nuclei of the hypothalamus, including the paraventricular nucleus (PVN) and the arcuate nucleus (Arc). These nuclei are the primary brain sites that are engaged in regulating body energy homeostasis, thus providing anatomical evidence to support a functional role of Sct in appetite control. In this study, the effect of Sct on feeding behavior was investigated using wild-type (wt), Sctâ/â, and secretin receptor-deficient (Sctrâ/â) mice. We found that both central and peripheral administration of Sct could induce Fos expression in the PVN and Arc, suggesting the activation of hypothalamic feeding centers by this peptide. Consistent with this notion, Sct was found to increase thyrotropin-releasing hormone and melanocortin-4 receptor (Mc4r) transcripts in the PVN, and augment proopiomelanocortin, but reduces agouti-related protein mRNA expression in the Arc. Injection of Sct was able to suppress food intake in wt mice, but not in Sctrâ/â mice, and that this effect was abolished upon pretreatment with SHU9119, an antagonist for Mc4r. In summary, our data suggest for the first time that Sct is an anorectic peptide, and that this function is mediated by the melanocortin system