Imaginal Feeding for Progression of Diapause Phenotype in the Two-Spotted Spider Mite (Acari: Tetranychidae).

Adult females of the two-spotted spider mite (Tetranychus urticae Koch) enter diapause under conditions of short-day length and low temperature. A conspicuous body color change, from greenish yellow to bright orange, accompanies diapause induction. This pigmentation is attributed to accumulation of keto-carotenoids produced internally from ß-carotene, which is a precursor of vitamin A essential for inducing diapause. The quantity of ß-carotene transferred from females to eggs has been considered sufficient to induce diapause. Moreover, carotenoid biosynthesis genes were recently found in this mite. Therefore, imaginal feeding is not likely to be necessary to progress to diapause. In contrast, diapause-induced adult females have been known to feed between the last molt and the time of body color changes. Consequently, the function of imaginal feeding in diapause-induced females was largely unknown. We aimed to clarify whether imaginal feeding was essential to enter diapause. First, we verified that body color change occurred in connection with the feeding behavior, and also verified the change in the composition of carotenoids in diapausing females. Subsequently, we tested the effects of restraints on feeding after molting on carotenoid composition and diapausing rates. Body color change required imaginal feeding. Fed, but not unfed, females accumulated astaxanthin. Moreover, starvation reduced diapausing rates. We concluded that imaginal feeding between the last molt and the time of body color change was necessary to progress to the diapausing phenotype and that starvation at the adult stage reduced the percentage of adults entering reproductive diapause.

Expression of Ins1 and Ins2 genes in mouse fetal liver.

A possible cure for diabetes is explored by using non-pancreatic cells such as fetal hepatocytes. The expression of insulin and transcription factors for insulin is investigated in mouse fetal liver. We detected mRNAs for insulin I (Ins1) and insulin II (Ins2) and proinsulin- and mature insulin-positive cells in mouse fetal liver by reverse transcription plus the polymerase chain reaction and immunohistochemistry. Glucagon, somatostatin and pancreatic polypeptide were not expressed throughout development. Mouse Ins2 and Ins1 promoters were transiently activated in mouse fetal hepatocytes of embryonic days 13.5 and 16.5, respectively. Pancreatic and duodenal homeobox 1 (Pdx1) mRNA was not expressed during development of the liver. In contrast, mRNAs and proteins of neurogenic differentiation (NeuroD)/ß cell E-box transactivator 2 (Beta2) and v-maf musculoaponeurotic fibrosarcoma oncogene homolog (MafA) were almost simultaneously expressed with insulin genes in the liver. Ins2 and Ins1 promoters were activated in hepatoma cells by the transfection of the expression vector for NeuroD/Beta2 alone and by the combination of NeuroD/Beta2 and MafA, respectively. These results indicate that the expression of NeuroD/Beta2 and MafA is linked temporally with the transcription of Ins2 and Ins1 genes in mouse fetal liver and suggest the potential usage of fetal hepatocytes to make insulin-producing ß cells by introducing transcription factors.

Cyclin D1 activation through ATF-2 in Reg-induced pancreatic beta-cell regeneration.

Regenerating gene product (Reg) is induced in pancreatic beta-cells and acts as an autocrine/paracrine growth factor for regeneration via a cell surface Reg receptor. However, the manner by which Reg induces beta-cell regeneration was unknown. In the present study, we found that Reg increased phospho-ATF-2, which binds to -57 to -52 of the cyclin D1 gene to activate the promoter. The Reg/ATF-2-induced cyclin D1 promoter activation was attenuated by PI(3)K inhibitors such as LY294002 and wortmannin. In Reg knockout mouse islets, the levels of phospho-ATF-2, cyclin D1, and phospho-Rb were greatly decreased. These results indicate that the Reg-Reg receptor system stimulates the PI(3)K/ATF-2/cyclin D1 signaling pathway to induce beta-cell regeneration.

Molecular cloning, expression and chromosomal localization of a novel human REG family gene, REG III.

Regenerating gene (Reg), first isolated from a regenerating islet cDNA library, encodes a secretory protein with a growth stimulating effect on pancreatic beta cells that ameliorates the diabetes of 90% depancreatized rats and non-obese diabetic mice. Reg and Reg-related genes have been revealed to constitute a multigene family, the Reg family, which consists of four subtypes (types I, II, III, IV) based on the primary structures of the encoded proteins of the genes [Diabetes 51(Suppl. 3) (2002) S462]. Plural type III Reg genes were found in mouse and rat. On the other hand, only one type III REG gene, HIP/PAP (gene expressed in hepatocellular carcinoma-intestine-pancreas/gene encoding pancreatitis-associated protein), was found in human. In the present study, we found a novel human type III REG gene, REG III. This gene is divided into six exons spanning about 3 kilobase pairs (kb), and encodes a 175 amino acid (aa) protein with 85% homology with HIP/PAP. REG III was expressed predominantly in pancreas and testis, but not in small intestine, whereas HIP/PAP was expressed strongly in pancreas and small intestine. IL-6 responsive elements existed in the 5'-upstream region of the human REG III gene indicating that the human REG III gene might be induced during acute pancreatitis. All the human REG family genes identified so far (REG Ialpha, REG Ibeta, HIP/PAP, REG III and REG IV) have a common gene structure with 6 exons and 5 introns, and encode homologous 158-175-aa secretory proteins. By database searching and PCR analysis using a yeast artificial chromosome clone, the human REG family genes on chromosome 2, except for REG IV on chromosome 1, were mapped to a contiguous 140 kb region of the human chromosome 2p12. The gene order from centromere to telomere was 5' HIP/PAP 3'-5' RS 3'-3' REG Ialpha 5'-5' REG Ibeta 3'-3' REG III 5'. These results suggest that the human REG gene family is constituted from an ancestor gene by gene duplication and forms a gene cluster on the region.

[A case of epidural hematoma associated with epidural catheterization which occurred on 12th days after the last medication of ticlopidine hydrochloride].

A 72-year-old woman underwent choledocholithotomy under general anesthesia combined with epidural block. She was complicated with hypertension, diabetes mellitus and angina pectoris, and was given ticlopidine hydrochloride. The medication was stopped 12 days before the operation. Her coagulation tests and platelet counts were within normal ranges. An epidural catheter was inserted at Th 9-10 interspace, and continuous epidural anesthesia was started for postoperative pain. Just after the operation, numbness and motor paralysis in both legs occurred. We stopped continuous epidural anesthesia, and the symptom on right leg improved. However, after 2 days, magnetic resonance imaging revealed epidural hematoma extending from Th7 to L1, and the patient underwent laminectomy. After a month, her motor paralysis in the left leg started to improve gradually. It is possible that the term of discontinuation of ticlopidine was not enough. We should stop antiplatelet drugs early enough, and should be aware of early symptoms of spinal cord compression.