Search

Urotensin II (UII) is a cyclic peptide that was originally extracted from the caudal neurosecretory system (CNSS) of fish. UII is well known to exhibit cardiovascular, ventilatory, and motor effects in vertebrates. Studies have reported that UII exerts mitogenic effects and can act as an autocrine/paracrine growth factor in mammals. However, similar information in fish is limited. In this study, the full-length cDNAs of UII and its receptor (UT) were cloned and characterized in the orange-spotted grouper. UII and UT were expressed ubiquitously in various tissues in grouper, and particularly high levels were observed in the CNSS, CNS, and ovary. A functional study showed that UT was coupled with intracellular Ca2C mobilization in HEK293 cells. Studies carried out using i.p. injections of UII in grouper showed the following: i) in the hypothalamus, UII can significantly stimulate the mRNA expression of ghrh and simultaneously inhibit the mRNA expression of somatostatin 1 (ss1) and ss2 3 h after injection; ii) in the pituitary, UII also significantly induced the mRNA expression of gh 6 and 12 h after injection; and iii) in the liver, the mRNA expression levels of ghr1/ghr2 and igf1/igf2 were markedly increased 12 and 3 h after the i.p. injection of UII respectively. These results collectively indicate that the UII/UT system may play a role in the promotion of the growth of the orange-spotted grouper. [ABSTRACT FROM AUTHOR]

Purpose: We induced neural stem cells (NSCs) to neurons by olfactory ensheathing cell (OEC) conditioned medium and characterized their electrophysiological properties after neuronal differentiation. Methods: Fetal NSCs and OECs were cultured from embryonic day 14 SD rats and the conditioned medium was collected and stored at -20°C when the cell number was up to 80% of the culture flasks. The experiment groups were divided into a control group (cultured with DMEM/F12 without FBS) and an OECs induction group (cultured with OEC conditioned medium and DMEM/F12 without FBS). Immunocytochemistry staining was carried out to identify the neurons derived from NSCs and their electrophysiological properties were characterized after neuronal differentiation using a patch-clamp technique. Results: The NSCs divided rapidly in the expansion medium, forming small proliferating spheres after 7 days. The OECs induction group presented an evident neuron-like type 7 days after adding OEC conditioned medium, and the nestin immunochemistry staining was positive. The electrophysiological characterization showed that the derived neurons presented a transient inward sodium current and slow outward potassium current under proper electric stimulus, which were blocked by tetrodotoxin (TTX) and tetraethylammonium (TEA). Conclusion: OEC conditioned medium can induce NSCs to form neurons, and electrophysiological characterization demonstrated that the derived neurons presented active electrophysiological properties which are essential for nervous excitation. [ABSTRACT FROM AUTHOR]

Growth hormone and insulin-like growth factors play important roles in the growth, development and metabolism of vertebrates. In this study, we used reverse transcription and rapid amplification of cDNA ends (RACE) to obtain the three full-length cDNA sequences encoding GH and two forms of IGF-I from the giant grouper ( Epinephelus lanceolatus), a coral fish of high commercial value cultured in Southeast Asia. GH precursor cDNA consists of 938 bp in size with an open-reading frame (ORF) encoding 204 amino acid (aa), a 65 bp 5′-untranslated region and a 236 bp 3′-untranslated region. The sequence of giant grouper GH shared 98.6% nucleotide sequence homology with orange-spotted grouper ( E. coioides) GH. Two forms of IGF-I precursor cDNA were cloned from giant grouper, IGF-I a consisting of 159 aa, and IGF-I b with 186 aa. They shared 98.4 and 98.7% aa identity with IGF-I reported in the orange-spotted grouper, respectively. Giant grouper IGF-I a and b have the same signal peptide and B-C-A-D domains, but they are different in the E domain. Using real-time reverse transcription PCR strategy, tissue distribution profile showed that GH and IGF-I mRNA signals were all observed in pituitary, brain, liver, ovary and spleen. GH mRNA in pituitary was the most abundant, and IGF-I mRNA level in liver was found to be more abundant than that in other selected tissues. These findings will contribute to the understanding of the evolution of GH and IGF-I, and provide some basic information about the characterization of GH and IGF-I in the giant grouper. [ABSTRACT FROM AUTHOR]

A systematic study was made on the topological nature of the system of non-static rotating fluid. Several initial (boundary) value problems and their well-posedness were discussed. [ABSTRACT FROM AUTHOR]

A necessary and sufficient conditions of the existence of formal solution to the initial value problem of Navier-Stokes equation on R3×R are presented. A computation case is also given [ABSTRACT FROM AUTHOR]