Insulin promotes the expression of the gluconeogenic rate-limiting enzymes phosphoenolpyruvate carboxykinase (Pepck) and glucose 6-phosphatase (G6pase) through PI3k/Akt/mTOR signaling pathway in goose hepatocytes

To identify what makes insulin have an activating or inhibiting role in gluconeogenesis in goose hepatocytes and whether insulin regulates PEPCK and G6Pase through the PI3k/Akt/mTOR pathway or not, goose primary hepatocytes were isolated and cultured in vitro. After 12h cultured in serum-free medium, hepatocytes were incubated for 24 h in the medium with no addition (control) or with the addition of 50, 100, and 150 nM of insulin, 1000 nM NVP-BEZ235, or co-addition of 150nM insulin and 1000nM NVP-BEZ235. Glucose concentration and PEPCK and G6Pase expression were determined. The results showed that PEPCK and G6Pase mRNA levels and activities were up regulated in the 50, 100, and 150nM insulin treatments, while glucose concentration was not significantly altered (p > 0.05). Compared with the activation role of 150nM insulin alone, the co-treatment with1000nM NVP-BEZ235 and 150nM insulin significantly down regulated PEPCK mRNA level and G6Pase protein activity (p < 0.05). However, there is a different result on mRNA level of G6Pase. In conclusion, G6Pase and PEPCK are up regulated by insulin through PI3k/Akt/mTOR pathway in goose hepatocytes. However, G6Pase mRNA and protein levels may be regulated by insulin through different signaling pathways.(AU)

Insulin promotes the expression of the gluconeogenic rate-limiting enzymes phosphoenolpyruvate carboxykinase (Pepck) and glucose 6-phosphatase (G6pase) through PI3k/Akt/mTOR signaling pathway in goose hepatocytes

To identify what makes insulin have an activating or inhibiting role in gluconeogenesis in goose hepatocytes and whether insulin regulates PEPCK and G6Pase through the PI3k/Akt/mTOR pathway or not, goose primary hepatocytes were isolated and cultured in vitro. After 12h cultured in serum-free medium, hepatocytes were incubated for 24 h in the medium with no addition (control) or with the addition of 50, 100, and 150 nM of insulin, 1000 nM NVP-BEZ235, or co-addition of 150nM insulin and 1000nM NVP-BEZ235. Glucose concentration and PEPCK and G6Pase expression were determined. The results showed that PEPCK and G6Pase mRNA levels and activities were up regulated in the 50, 100, and 150nM insulin treatments, while glucose concentration was not significantly altered (p > 0.05). Compared with the activation role of 150nM insulin alone, the co-treatment with1000nM NVP-BEZ235 and 150nM insulin significantly down regulated PEPCK mRNA level and G6Pase protein activity (p < 0.05). However, there is a different result on mRNA level of G6Pase. In conclusion, G6Pase and PEPCK are up regulated by insulin through PI3k/Akt/mTOR pathway in goose hepatocytes. However, G6Pase mRNA and protein levels may be regulated by insulin through different signaling pathways.

PI3K-Akt-mTOR signal inhibition affects expression of genes related to endoplasmic reticulum stress.

PI3K-Akt-mTOR signaling pathway is associated with endoplasmic reticulum (ER) stress. However, it is not clear how this signaling pathway affects the ER stress. The present study aimed to determine whether the PI3K-Akt-mTOR signaling pathway regulates tunicamycin (TM)-induced increases in mRNA levels of genes involved in the ER stress, to help elucidate the mechanism by which this pathway affects the ER stress in primary goose hepatocytes. Primary hepatocytes were isolated from geese and cultured in vitro. After 12 h in a serum-free medium, the hepatocytes were incubated for 24 h in a medium with either no addition (control) or with supplementation of TM or TM together with PI3K-Akt-mTOR signaling pathway inhibitors (LY294002, rapamycin, NVP-BEZ235). Thereafter, the expression levels of genes involved in the ER stress (BIP, EIF2a, ATF6, and XBP1) were assessed. The results indicated that the mRNA level of BIP was up-regulated in 0.2, 2, and 20 µM TM treatment group (P < 0.05), whereas the mRNA levels of EIF2a, ATF6, and XBP1 were up-regulated in the 2 µM TM treatment group (P < 0.05). However, the TM mediated induction of mRNA levels of genes involved in the ER stress (BIP, EIF2a, ATF6, and XBP1) was down-regulated after the treatment with PI3K-Akt-mTOR pathway inhibitors (LY294002, NVP-BEZ235, and rapamycin). Therefore, our results strongly suggest that the PI3K-Akt-mTOR signaling pathway might be involved in the down-regulation of the TM-induced ER stress in primary goose hepatocytes.

Root tip chromosome karyotype analysis of hyacinth cultivars.

Karyotype analysis in plants helps to reveal the affinity relationships of species and their genetic evolution. The current study aimed to observe chromosome karyotypes and structures of Hyacinthus orientalis. Twenty hyacinth cultivars were introduced from Holland, and their water-cultivated root tips were used as experimental samples. A solution of colchicine (0.02%) and 8-hydroxyquinoline (0.02 M) was used as a 20-h pre-treatment. Subsequently, Carnot I was used for fixation and 45% acetic acid was used for dissociation. The squash method was selected to prepare chromosome spreads for microscopic observation. The basic chromosome number of the hyacinth cultivar was 8, and the number of chromosomes in the diploid, triploid, tetraploid, and aneuploid cultivars was 16, 23, 24, 31, and 32, respectively. The L-type chromosome was predominant in the chromosomal composition. The hyacinth satellite was located on the short arm in numbers equivalent to the ploidy. This satellite is located on the middle-sized chromosome in the fourth group of chromosomes, demonstrating that Hyacinthus has a more primitive evolution than Lilium and Polygonatum. Among 20 hyacinth cultivars, 'Fondant' had the highest level of evolution and a maximum asymmetric coefficient of 61.69%. Moreover, the ratio between the shortest and longest chromosomes in this cultivar was 4.40, and its karyotype was type 2C. This study may elucidate long-term homonym and synonym phenomena. It may also provide a method of cytological identification as well as direct proof of the high outcross compatibility between hyacinth cultivars.

Cloning and characterization of peanut allene oxide cyclase gene involved in salt-stressed responses.

In this study, the full-length cDNA encoding allene oxide cyclase (AhAOC) was isolated from peanut (Arachis hypogaea L.). The deduced amino acid sequence of AhAOC showed high homology with other plant AOCs. The transcript of AhAOC was found to be abundantly expressed in roots. Expression analysis demonstrated that AhAOC was induced by abscisic acid, methyl-jasmonic acid, salicylic acid, salinity, polyethylene glycol, and cold stresses, particularly by high salinity. Overexpression of AhAOC in rice increased root elongation and plant height compared with expression in control plants and conferred tolerance against salinity. Thus, the AhAOC gene may play an important role in increasing the expression of transcription factors (MYB2 and OsONAC045) and functional genes (DREB1F and LEA3) in transgenic rice under salt stress as well as improve stress tolerance through the accumulation of compatible solutes (proline and soluble sugar). The AhAOC gene is a potential resource for enhancing salt tolerance in crop species.

SNPs in the 5'-regulatory region of the tyrosinase gene do not affect plumage color in ducks (Anas platyrhynchos).

Tyrosinase, encoded by the TYR gene, is the rate-limiting enzyme in the production of melanin pigment. In this study, plumage color separation was observed in Cherry Valley duck line D and F1 and F2 hybrid generations of Liancheng white ducks. Gene sequencing and bioinformatic analysis were applied to the 5'-regulatory region of TYR, to explore the connection between TYR sequence variation and duck plumage color. Four SNPs were found in the 5'-regulatory region. The SNPs were in tight linkage and formed three haplotypes. However, the genotype distribution in groups with different plumage color was not significantly different, and there were no changes in the transcription factor binding sites between the different genotypes. In conclusion, these SNP variations may not cause the differences in feather color observed in this test group.

Expression profile of insulin-like growth factor system genes in muscle tissues during the postnatal development growth stage in ducks.

Insulin-like growth factors (IGFs) are regulators that modulate the proliferation and differentiation of muscle tissues. We quantified the messenger RNA (mRNA) expression of IGF-I, IGF-II, and type I and II IGF receptors (IGF-IR and IGF-IIR) in muscle tissues including the breast, leg, and myocardium during an early postnatal development growth stage (post-hatching weeks 1-8) in ducks. The results showed a significant age-related change in mRNA in these muscle tissues. In breast muscle, the developmental expression of IGF-I and IGF-II was highest during week 1 but decreased quickly and maintained a relatively lower level. Leg muscle had the highest mRNA expression of IGF-I and IGF-II genes at week 3. In myocardial tissues, the expression level of IGF-IR and IGF-IIR genes exhibited a "rise-decline" developmental trend. The expression patterns of IGF-I/IGF-IR and IGF-II/IGF-IIR were different between weeks 4 and 6. The same expression pattern was observed for IGF-I and IGF-IR; however, it was different from that observed for IGF-II and IGF-IIR. Our results showed a negative correlation between IGF-II mRNA expression and leg muscle weight at week 4 (P < 0.05). A negative correlation was also found between IGF-II mRNA expression and breast muscle weight (P < 0.01), and a positive correlation was found between IGF-IR expression and breast muscle weight. At week 6, a positive correlation was found between IGF-IR expression and breast muscle weight. However, at week 8, a negative correlation was found between IGF-IR expression and breast muscle weight. The results showed that the expression of IGF mRNA in duck tissues exhibits a specific developmental trend and an age-related pattern, suggesting that the regulation mechanism of these 4 genes in proliferation and differentiation of muscle tissues differed.