内吞作用与胚胎诱导

在两柄类胚胎初级诱导的研究中,诱导物质如何进入反应细胞是一个受到重视(Grunzand Staubach,1979;Toivonen,1979)、但是仍未能解决的问题。为了对这一问题有所阐明,进行了离体诱导实验和电镜的观察。东方蝾螈(Cynops orientalis)早期原肠胚的外胚层块用豚鼠骨髓粗提液(BME)——有效的中胚层诱导物(Toivonen,1953)——处     

Quercetin supplementation suppresses the secretion of pro-inflammatory cytokines in the lungs of Mongolian gerbils and in A549 cells exposed to benzo[a]pyrene alone or in combination with β-carotene: in vivo and ex vivo studies

In vitro studies have shown that quercetin modulates the effects of β-carotene induced by stimulants. Whether these reactions happen in vivo, however, is unclear. Thus, we investigated whether quercetin supplementation suppresses the harmful effects of benzo[a]pyrene (BaP) alone or combined with β-carotene in the lungs of Mongolian gerbils. The gerbils were given quercetin (100 mg/kg body wt, 3 times/week), β-carotene (10 mg/kg body wt, 3 times/week), and BaP (8 mmol, 2 times/week) alone or in combination by gavage for 6 months. β-Carotene supplementation enhanced the pro-inflammatory effects of BaP in the lungs of gerbils. In contrast, quercetin supplementation significantly decreased the infiltration of inflammatory cells as well as the levels of TNF-α and IL-1β in the bronchoalveolar lavage fluid and plasma of gerbils exposed to BaP or BaP+β-carotene (P<.05). Such effects of quercetin supplementation were accompanied by a down-regulation of the expression of phospho-c-Jun and phospho-JNK induced by BaP or BaP+β-carotene in the lungs of gerbils. Furthermore, in the ex vivo study, we found that quercetin-metabolite-enriched plasma (QP) obtained from gerbils acted like a JNK inhibitor to significantly suppress the secretion of pro-inflammatory cytokines induced by BaP or BaP+β-carotene in A549 cells (P<.05). QP also suppressed the activation of the JNK pathway in the A549 cells. These results suggest that supplemental quercetin suppress the pro-inflammatory effect of β-carotene induced by BaP in vivo and ex vivo. The regulation of the JNK pathway by the metabolites of quercetin contributes, at least in part, to such effects of quercetin in vivo.     

A new model for fish ion regulation: identification of ionocytes in freshwater- and seawater-acclimated medaka (Oryzias latipes)

The ion regulation mechanisms of fishes have been recently studied in zebrafish (Danio rerio), a stenohaline species. However, recent advances using this organism are not necessarily applicable to euryhaline fishes. The euryhaline species medaka (Oryzias latipes), which, like zebrafish, is genetically well categorized and amenable to molecular manipulation, was proposed as an alternative model for studying osmoregulation during acclimation to different salinities. To establish its suitability as an alternative, the present study was conducted to (1) identify different types of ionocytes in the embryonic skin and (2) analyze gene expressions of the transporters during seawater acclimation. Double/triple in situ hybridization and/or immunocytochemistry revealed that freshwater (FW) medaka contain three types of ionocyte: (1) Na⁺/H⁺ exchanger 3 (NHE3) cells with apical NHE3 and basolateral Na⁺-K⁺-2Cl^? cotransporter (NKCC), Na⁺-K⁺-ATPase (NKA) and anion exchanger (AE); (2) Na⁺-Cl^? cotransporter (NCC) cells with apical NCC and basolateral H⁺-ATPase; and (3) epithelial Ca²⁺ channel (ECaC) cells [presumed accessory (AC) cells] with apical ECaC. On the other hand, seawater (SW) medaka has a single predominant ionocyte type, which possesses apical cystic fibrosis transmembrane conductance regulator (CFTR) and NHE3 and basolateral NKCC and NKA and is accompanied by smaller AC cells that express lower levels of basolateral NKA. Reciprocal gene expressions of decreased NHE3, AE, NCC and ECaC and increased CFTR and NKCC in medaka gills during SW were revealed by quantative PCR analysis.     

High-throughput sex identification by melting curve analysis in blue-breasted quail and chicken

The objective was to develop a high-throughput method of identifying sex in both Coturnix chinensis and Gallus gallus, which would be useful for biomedical research and hatcheries. Because chromo-helicase-DNA binding protein (CHD)-based Griffiths P2/P8 primers do not produce polymerase chain reaction (PCR) products with distinguishable sex-specific curves in melting curve analysis (MCA), these primers are unsuitable for high throughput application in either species. Conserved regions were identified by basic local alignment search tool (BLAST) analyses of cloned CHD-Z and CHD-W genes of C. chinensis. Based on sequence alignment, a female-specific CHD-W primer (W-cot-F1) and a female/male (or CHD-W/CHD-Z)-common primer (ZW-cot-F1) were redesigned for use in combination with the Griffiths P2 primer for MCA-based PCR reaction. In C. chinensis and G. gallus, W-cot-F1/P2 and ZW-cot-F1/P2 had amplicon lengths of 315/318 and 114 base pairs and melting temperatures (Tm) of approximately 79.5 °C to 80 °C and approximately 78.5 °C to 79°C, respectively. Thus, MCA distinguished sex based on two distinct Tm peaks in females versus only one Tm peak in males. The MCA-based real-time PCR combined with the proposed primer redesign provided a high-throughput method of identifying sex in C. chinensis and G. gallus.     

Partial cross tolerance to D-Ala2-D-Leu5-enkephalin after chronic spinal morphine infusion

The development of tolerance to morphine and cross tolerance to D-Ala2-D-Leu5-enkephalin (DADL) at spinal cord level to the inhibition of tail flick response was studied in rats tolerant to morphine. The long term intrathecal infusion of morphine sulfate was accomplished by means of an osmotic minipump. Intrathecal infusion of morphine sulfate (2 micrograms/hr) markedly elevated the tail flick latency measured 24 hr after the start of infusion. The increased tail flick latencies gradually decreased during 6 days of intrathecal infusion of morphine sulfate. Tolerance to morphine and DADL was determined by inhibition to the tail flick response after intrathecal administration of cumulative doses of morphine sulfate and DADL. Chronic intrathecal infusion of morphine induced a marked tolerance to morphine but developed only a slight cross tolerance to DADL. The results indicate that there exists two separate types of opioid receptor, mu- and delta-opioid receptor in the spinal cord of rats.     

Rho kinase regulates the intracellular micromechanical response of adherent cells to rho activation

Local sol-gel transitions of the cytoskeleton modulate cell shape changes, which are required for essential cellular functions, including motility and adhesion. In vitro studies using purified cytoskeletal proteins have suggested molecular mechanisms of regulation of cytoskeleton mechanics; however, the mechanical behavior of living cells and the signaling pathways by which it is regulated remains largely unknown. To address this issue, we used a nanoscale sensing method, intracellular microrheology, to examine the mechanical response of the cell to activation of the small GTPase Rho. We observe that the cytoplasmic stiffness and viscosity of serum-starved Swiss 3T3 cells transiently and locally enhances upon treatment with lysophosphatidic acid, and this mechanical behavior follows a trend similar to Rho activity. Furthermore, the time-dependent activation of Rho decreases the degree of microheterogeneity of the cytoplasm. Our results reveal fundamental differences between intracellular elasticity and cellular tension and suggest a critical role for Rho kinase in the regulation of intracellular mechanics.     

A Fourier-transform infrared spectroscopic analysis of organic matter degradation in a bench-scale solid substrate fermentation (composting) system

The degradation of organic matter was evaluated by a quantitative Fourier transform infrared spectroscopy (FTIR) analysis technique. The degradation process was conducted in a bench-scale reactor under controlled operational conditions of 50 degrees C, with 50-60% moisture content, and subjected to uniform aeration for 325 h. During the composting process, ATP concentration increased from 0.1 to 8 mug/g and the maximum CO(2) evolution and O(2) consumption rates reached 0.04 and 0.085 mmol/g-h, respectively. Polysaccharide content decreased approximately 50% while lignin content remained unchanged. Three regions of the FTIR spectra were used for quantification: 1070-974, 1705-1614, and 2995-2887 cm(-1), which correspond to polysaccharides and aromatic and aliphatic compounds, respectively. The actual spectra quantification consisted of peak identification using a second derivative and curve fitting technique, followed by normalization using the internal standard CaCO(3). The results obtained with the spectra quantification technique was then compared to commonly used wet chemistry extraction procedures. Reasonable correlation between the two techniques was obtained. (c) 1996 John Wiley & Sons, Inc.     

APP processing is regulated by cytoplasmic phosphorylation

Amyloid-beta peptide (Abeta) aggregate in senile plaque is a key characteristic of Alzheimer's disease (AD). Here, we show that phosphorylation of amyloid precursor protein (APP) on threonine 668 (P-APP) may play a role in APP metabolism. In AD brains, P-APP accumulates in large vesicular structures in afflicted hippocampal pyramidal neurons that costain with antibodies against endosome markers and the beta-secretase, BACE1. Western blot analysis reveals increased levels of T668-phosphorylated APP COOH-terminal fragments in hippocampal lysates from many AD but not control subjects. Importantly, P-APP cofractionates with endosome markers and BACE1 in an iodixanol gradient and displays extensive colocalization with BACE1 in rat primary cortical neurons. Furthermore, APP COOH-terminal fragments generated by BACE1 are preferentially phosphorylated on T668 verses those produced by alpha-secretase. The production of Abeta is significantly reduced when phosphorylation of T668 is either abolished by mutation or inhibited by T668 kinase inhibitors. Together, these results suggest that T668 phosphorylation may facilitate the BACE1 cleavage of APP to increase Abeta generation.