Two distinct conformations of the conserved RNA-rich decoding center of the small ribosomal subunit are recognized by tRNAs and release factors

The mRNA is bound and poised in the decoding center of the small subunit of the ribosome where the genetic code is translated by the tRNAs, which recognize sense codons, and by the release factors, which recognize stop-codons. Structural and biochemical studies have identified key universally conserved nucleotides, G530, A1492, and A1493, that are important for selection of cognate tRNA species during elongation. Here, we present evidence that these same universally conserved nucleotides are also important for interactions with the release factors, but must assume a very different structure during stopcodon recognition. These data provide mechanistic insight into how the decoding center of the ribosome has evolved to recognize distinct substrates with high fidelity, which in turn regulates the downstream chemical events of peptidyl transfer and peptide release.

The taxane-enhancer STA-4783 induces Hsp70 expression and apoptosis via an oxidative stress mechanism

14107

Background: STA-4783 is an inducer of Hsp70 expression and apoptosis that recently completed a successful Phase II clinical trial in melanoma. In a double-blind, randomized, controlled trial in patients with Stage IV disease, STA-4783 plus paclitaxel doubled progression-free survival compared to paclitaxel alone (Perspectives in Melanoma X and the Third International Melanoma Research Congress, 2006). The mechanism by which STA-4783 synergizes with paclitaxel is not fully understood. To identify the major pathway modulated by STA- 4783 in vitro, a transcriptional profiling analysis of drug-treated melanoma cells was performed. Methods: Transcriptional profiling was performed on Hs294T and MDA-MB-435 melanoma cell lines treated with STA-4783. The induction of Hsp70 RNA and other human genes was monitored by Real Time-PCR (RT-PCR) analysis. Measurement of reactive oxygen species (ROS) was performed in human cells using the Carboxy-H2DCFDA probe. Levels of apoptotic cell death were determined by flow cytometry analysis using an Annexin V specific probe. Results: Transcriptional profiling revealed that STA-4783 induced the expression of numerous gene families known to be regulated by oxidative stress, including heat shock proteins and metallothioneins. STA-4783 induced the generation of ROS in cells resulting in the oxidation and activation of the Carboxy-H2DCFDA fluorescent probe. The antioxidants N-Acetyl Cysteine (NAC) and Tiron potently blocked the induction of Hsp70 RNA and apoptotic cell death. Conclusions: STA-4783 induces oxidative stress in cells resulting in Hsp70 induction and apoptotic cell death. Although STA-4783 initially induced a transient protective response, apoptotic cell death occurred due to sustained oxidative stress. Cancer cells produce more ROS than normal cells and are thus more sensitive to insults that induce oxidative stress. The induction of ROS in melanoma cells by STA-4783 may therefore enhance the efficacy of paclitaxel in vivo. STA-4783 belongs to a novel class of anticancer agents that induce cell death by pushing the cancer cell beyond its oxidative stress breaking point.

[Table: see text]

A rapid immunoassay to determine concentrations of busulfan in plasma

7111

Background: High-dose busulfan is an important component of many bone marrow transplantation preparative regimens. High busulfan plasma levels have been shown to increase the chance of veno-occlusive disease and low levels are associated with recurrence of disease or graph rejection. Currently, busulfan levels are monitored by physical methods which are expensive and time- consuming, resulting in relatively low overall use of busulfan testing for dose adjustment. Methods: Novel, highly selective antibodies for busulfan have been generated and micro-titer plate immunoassays that are capable of quantifying busulfan levels in plasma have been developed. The assay was configured using a busulfan-horseradish peroxidase conjugate as the reporter group and busulfan monoclonal antibodies. The assay requires only 5 μL of plasma per determination with no sample preparation. Results: The immunoassay has a standard curve based on busulfan with a range of 75 to 2,000 ng/mL. The time to first result is 30 minutes with up to 240 tests generated per hour. The coefficient of variation (CV) on signal is < 5% for an entire plate and the 95% confidence interval for negative samples (n=78) is below the lowest calibrator of 75 ng/mL. Cross-reactivity with the major inactive metabolites (tetrahydrothiophene,tetramethyl sulfone and tetrahydrothiophene-3-ol-1,1-dioxide), are <0.1%. Clinical samples (n=70) correlate well to LC-MSMS or GC-MS (R > 0.97) with a slope of < 1.05. Conclusions: This immunoassay method may be suitable for determining levels of busulfan in human plasma. It offers the advantages of using a smaller sample size, does not require sample preparation and is less labor intensive than other methods. The ability to make 240 determinations per hour enables effective routine monitoring of busulfan levels in clinical practice.

No significant financial relationships to disclose.

Early onset vitreous amyloidosis in familial amyloidotic polyneuropathy with a transthyretin Glu54Gly mutation is associated with elevated vitreous VEGF

AIM

To report the early vitreous involvement in a rare familial amyloidotic polyneuropathy (FAP) mutation and associated vitreous vascular endothelial growth factor (VEGF) levels.

DESIGN

Observational case series.

METHODS

Review of clinical, pathological, photographic, and angiographic records of two FAP siblings with severe vitreous involvement. Laboratory ELISA analysis of vitreous samples for VEGF, and DNA sequence analysis of peripheral blood for transthyretin (TTR) mutational analysis.

RESULTS

Two patients underwent 25-gauge vitrectomy in three eyes with marked improvement of visual acuity. Neovascularisation seen intraoperatively responded to endolaser. Analysis of vitrectomy samples for VEGF showed raised levels in all three specimens. Mutational analysis revealed an isolated Glu54Gly mutation in the transthyretin gene.

CONCLUSIONS

Early involvement of the vitreous occurs in a rare transthyretin mutation of FAP, with increased vitreous levels of VEGF.

272 EXPRESSION OF Lef1 TRANSCRIPTION FACTOR AND ITS NOVEL ISOFORMS IN PRE-IMPLANTATION EMBRYOS

Lymphoid enhancer-binding factor 1 (Lef1) is a key transcriptional factor in the Wnt signaling pathway. Recently, the Wnt pathway has been shown to function in human and mouse embryonic stem cells; however, its role in ES cell differentiation and self-renewal remains contradictory. Our lab has identified two novel Lef1 isoforms, Lef1Δ2,3,6 and Lef1Δ6, that are transcribed in mouse embryonic stem cells in addition to the full-length Lef1. Both Lef1Δ2,3,6 and Lef1Δ6 contain an N-terminal β-catenin binding domain and a C-terminal HMG DNA binding domain. However, Lef1Δ2,3,6 lacks exons II, III, and VI, and Lef1Δ6 lacks exon VI. Exons II, III, and VI are a part of the context-dependent repression domain, whereas exon VI contains a Groucho binding motif. The absence of these repression domains suggests that Lef1Δ2,3,6 and Lef1Δ6 may be regulated differently than the full-length Lef1. In this study, we determined the expression patterns of Lef1 mRNA and the two isoforms during murine and bovine pre-implantation development using RT-PCR. Total RNA was isolated from pools of 10–20 in vitro-produced bovine embryos at the 2-cell, 4–8 cell, morulae, and blastocyst stages and in vivo-derived mouse embryos at the 8-cell, morula, and blastocyst stages using a Stratagene Nanoprep kit. Reverse transcription was performed using the Invitrogen Supercript III first-strand synthesis system. PCR was then completed using Invitrogen Platinum Taq DNA Polymerase. As determined in preliminary work, full-length Lef1 was expressed in 8-cell-stage mouse embryos but was not detectable in morulae and was only slightly expressed in mouse blastocysts. In contrast, Lef1Δ6 mRNA was not detectable in 8-cell mouse embryos, but became obvious at morula and blastocyst stages. Similarly, in bovine embryos, full-length Lef1 was detected at early cleavage stages (2–8 cells) with undetectable or low levels at the morula and blastocyst stages; however, unlike what was observed in the mouse embryos, Lef1Δ6 was expressed in all stages of bovine embryos tested. Lef1Δ2,3,6 was very low (mouse) or undetected (bovine). Because Lef1 appears to be playing a critical role in response to Wnt differentiation signals in mouse embryonic stem cells (He, unpublished), further exploration of these transcription factors and their regulation in developing mammalian embryos is critical to understanding the process of initial embryonic differentiation.

Impact of Lotensin and Salviae on the changes of TGF-beta1 and its receptors in a rat model of chronic cyclosporine-induced nephropathy

OBJECTIVES

Transforming growth factor-beta(1) (TGF-beta(1)) and its receptors, type 1 (TR-1) and type 2 (TR-2) play important roles in chronic cyclosporine (CsA)-induced nephropathy. Lotensin is known as an angiotensin-converting enzyme inhibitor and may reduce chronic CsA-induced nephropathy. Recently it is reported that Salviae (a Chinese medicine), which can improve microcirculation and decrease the expression of TGF-beta(1) has the same effect as that of lotensin. Therefore, in this study we assessed the effects of Lotensin or Salviae on the chronic CsA-induced upregulation of TGF-beta(1), TR-1, and TR-2 in a rat model.

MATERIALS AND METHODS

Sodium-depleted rats were administered CsA by gastric gavage and a new rat model of chronic CsA-induced nephropathy was established. Rats with chronic CsA-induced nephropathy were treated by lotensin or Salviae. The proteins of TGF-beta(1), TR-1, and TR-2, and the mRNA of TR-1 and TR-2 in the kidneys of CsA-treated rats, were measured by immunohistochemistry (IHC) and in situ hybridization (ISH). The results were investigated semiquantitatively by image analysis.

RESULTS

Lotensin or Salviae individually attenuated CsA-induced nephropathy in the rat models, and downregulated the protein expressions of TGF-beta(1), TR-1, and TR-2, and the mRNA transcripts of TR-1 and TR-2 in the rat model.

CONCLUSION

Our studies show that treatment with lotensin or Salviae is useful in preventing chronic CsA-induced nephropothy.

Production, characterization, and applications of two novel monoclonal antibodies against human interleukin-28A

Interleukin-28A (IL-28A) is a novel cytokine discovered in recent years and has been shown to have antiviral activity. In this study, IL-28A complementary DNA was inserted into prokaryotic expression vector pET-44 Ek/LIC. The Nus-S-His-tagged IL-28A fusion protein was expressed in Escherichia coli BL21 (DE3) in the soluble fraction. The fusion protein was purified by S-protein agarose affinity chromatography, and the fusion tag was removed from recombinant IL-28A by cleavage with thrombin. To prepare specific monoclonal antibody against human IL-28A, BALB/c mice were immunized with IL-28A, and hybridoma cell lines were obtained by fusing mouse spleen cells with myeloma NS-1 cells. Two strains of hybridoma cells, which produced the anti-human IL-28A antibodies 1B9 and 4B5 were obtained. They are IgM isotype and working in western blot analysis and enzyme-linked immunosorbent assay. In the present study, it was shown for the first time that human umbilical vein endothelial cells treated with interferon-alpha and poly(I:C) express IL-28A protein assessed by flow cytometry and immunofluorescent staining techniques. Immunohistochemistry showed that macrophage-like cells in colon and lung tissue and alveolar epithelial cells in lung tissue contain IL-28A, indicating a novel mechanism for both cell types to carry out their antivirus or antitumor functions.

Preparation, characterization and epitope mapping of monoclonal antibodies specific to human mast cell carboxypeptidase

Human mast cell carboxypeptidase (hMC-CP) is a unique product of mast cells. Unlike tryptase and chymase, its potential function and expression in diseased conditions remain largely unknown. To develop an assay for hMC-CP, the recombinant fusion protein of hMC-CP and purified native skin hMC-CP was prepared, and two novel monoclonal antibodies against hMC-CP named CCP1 (IgG1 isotype) and CCP2 (IgM isotype) were raised in the present study. Epitope analysis shows that CCP1 and CCP2 antibodies recognize epitopes located in the region of amino acids 112-202 of hMC-CP, and hydrophilicity analysis implies that epitopes might be located in the amino acid residues 123-134 and 165-177. Furthermore, using a competition enzyme-linked immunosorbent assay, it was shown that the epitope recognized by CCP1 is close to that recognized by CCP2 or the two antibodies partially share the same epitope. Flow cytometry analysis shows that basophilic leukemia cell line KU812 reacts with both CCP1 and CCP2 antibodies, suggesting that this cell line expresses hMC-CP. In conclusion, although the two antibodies possess different isotypes, they may partially share the same epitope. These two antibodies will be valuable tools for the development of an assay to detect the levels of hMC-CP in the biological fluids in man.

Stem cell self-renewal and cancer cell proliferation are regulated by common networks that balance the activation of proto-oncogenes and tumor suppressors

Networks of proto-oncogenes and tumor suppressors that control cancer cell proliferation also regulate stem cell self-renewal and possibly stem cell aging. Proto-oncogenes promote regenerative capacity by promoting stem cell function but must be balanced with tumor suppressor activity to avoid neoplastic proliferation. Conversely, tumor suppressors inhibit regenerative capacity by promoting cell death or senescence in stem cells. For example, the polycomb family proto-oncogene, Bmi-1, is consistently required for the self-renewal of diverse adult stem cells, as well as for the proliferation of cancer cells in the same tissues. Bmi-1 promotes stem cell self-renewal partly by repressing the expression of Ink4a and Arf, tumor suppressor genes that are commonly deleted in cancer. Despite ongoing Bmi-1 expression, Ink4a expression increases with age, potentially reducing stem cell frequency and function. Increased tumor suppressor activity during aging therefore may partly account for age-related declines in stem cell function. Thus, networks of proto-oncogenes and tumor suppressors have evolved to coordinately regulate stem cell function throughout life. Imbalances within such networks cause cancer or premature declines in stem cell activity that resemble accelerated aging.

Induction of interleukin-6 release from monocytes by serine proteinases and its potential mechanisms

Serine proteinases have been recognized playing an important role in inflammation via proteinase-activated receptors (PAR). However, little is known of the influence of serine proteinases and PAR on interleukin-6 (IL-6) secretion from highly purified monocytes. We challenged monocytes from human peripheral blood with serine proteinases and agonist peptides of PAR and measured the levels of IL-6, IL-1beta and IL-12 in culture supernatants by enzyme-linked immunosorbent assay. The results showed that thrombin, trypsin, tryptase and elastase stimulated approximately up to 2.9-, 2.0-, 1.8- and 2.1-fold increase in IL-6 release from monocytes following 16 h of incubation, respectively. Proteinase inhibitors inhibited the actions of proteinases on monocytes. Agonist peptides of PAR-1 (SFLLR-NH(3)) and PAR-4 (GYPGQV-NH(2)), but not PAR-3 (TFRGAP-NH(2)), also induced IL-6 release from monocytes. The proteinases and agonists of PAR failed to stimulate IL-1beta and IL-12 secretion. In conclusion, the induction of IL-6 secretion by serine proteinases may be through the activation of PAR.

Antitumor activities of the four sesquiterpene lactones from Elephantopus scaber L

AIM

To evaluate antitumor activity of sesquiterpene lactones (scabertopin (ES-2), isoscabertopin (ES-3), deoxyelephantopin (ES-4), isodeoxyelephantopin (ES-5)) isolated from Elephantopus scaber L. in vitro and in vivo.

METHODS

SMMC-7721, Caco-2 and HeLa cell lines were treated with ES-2,3,4,5. Cell viability was determined by MTT assay. Agarose gel electrophoresis was used to detect DNA fragmentation. To evaluate in vivo antitumor activity of ES-4, experimental murine tumor model was used.

RESULTS

It was shown that ES-2, ES-4, ES-5 exhibited significant antitumor effect in vitro in a concentration-dependent manner. However, the effect of ES-3 on the growth of tested cell lines was relatively weak. In HeLa cells exposed to ES-4 for 48 h, morphological changes and DNA ladder pattern evidencing on apoptosis were detected. ES-4 revealed in vivo antitumor activity.

CONCLUSION

Antitumor activity of studied sesquiterpene lactones may be due, at least in part, to induction of apoptosis in vitro. ES-4 possesses also antitumor activity in vivo.

Fine-scale differences between Accumulibacter-like bacteria in enhanced biological phosphorus removal activated sludge

A lab-scale sequencing batch reactor (SBR) and six full-scale wastewater treatment plants (WWTPs) performing enhanced biological phosphorus removal (EBPR) were surveyed. The abundance of Accumulibacter-related organisms in the full-scale plants was investigated using fluorescent in situ hybridization. Accumulibacter-related organisms were present in all of the full-scale EBPR plants, at levels ranging from 9% to 24% of total cells. The high percentage of Accumulibacter-related organisms seemed to be associated with configurations which minimize the nitrate recycling to the anaerobic zone and low influent BOD:TP ratios. PCR-based clone libraries were constructed from the community 16S rRNA gene plus the internally transcribed spacer region amplified from the SBR and five of the full-scale WWTPs. Comparative sequence analysis was carried out using Accumulibacter-related clones, providing higher phylogenetic resolution and revealing finer-scale clustering of the sequences retrieved from the SBR and full-scale EBPR

The Role of Alteration of Glutamic Acid and Gaba in Learning and Memory Impairment of Rats Induced by Aluminum

Aluminum exposure has been reported to be related to learning and memory impairment. This study examines the role of aluminum in alterating amino acids of the cerebral cortex of rats. The Step-down type tests were performed to investigate the alteration of learning and memory of rats induced by aluminum. The amino acids in the cerebral cortex were detected by high performance liquid chromatography (HLPC). Results show that the amounts of aluminum in the cerebral cortex increased by 5.0mgAl3+/(Kg·BW) group and 10.0mg Al3+/(Kg·BW) group. In the Step-down type test, the EN1 increased significantly in the Al3+ 10.0mg/(Kg·BW) group. The latency shortened obviously and the EN2 increased significantly in the 10.0mg Al3+/(Kg·BW) group. The content of Glu (Glutamic acid) increased but the content of GABA (gamma-aminobutyric acid) decreased significantly in the 10.0mg Al3+/(Kg·BW) group. This present study shows evidence that the disorder of amino acid neurotransmitters system plays an important role in the impairment of learning and memory of rats induced by aluminum.

[Carboxyamido-triazole inhibits substeps of choroidal neovascularization on retinal pigment epithelial cells and choroidal endothelial cells in vitro]

BACKGROUND

Retinal pigment epithelial cells (RPE cells) and choroidal endothelial cells (CECs) are important cell types in the process of choroidal neovascularization in exudative age-related macular degeneration (AMD). In this study, we evaluated the antiproliferative and antimigratory abilities of carboxyamido-triazole (CAI), a drug modulating calcium-dependent signal transduction on RPE cells and CECs.

METHODS

Human fetal RPE cells and bovine CECs were exposed to CAI in a concentration range of 0.1 to 10 microM. Cell proliferation was stimulated with 10% serum or 10 ng/ml bFGF. The effect of CAIs on cell proliferation was estimated. Furthermore, we evaluated CAI's effects on CEC and RPE cell migration induced by fibronectin.

RESULTS

CAI had a stronger inhibitory effect on serum-induced CEC proliferation than on RPE cell proliferation. A much stronger effect was seen on the proliferation of bFGF-stimulated RPE cells and CECs. Furthermore, the fibronectin-stimulated migration of RPE cells and CECs was inhibited by CAI. In this assay, a stronger inhibitory effect was seen on RPE cells than on CECs. CONCLUSION; CAI inhibits important substeps of choroidal neovascularization on RPR cells and CECs. Therefore, CAI may be of value for the treatment of choroidal neovascularization in exudative AMD.

RPGR ORF15 isoform co-localizes with RPGRIP1 at centrioles and basal bodies and interacts with nucleophosmin

The ORF15 isoform of RPGR (RPGR(ORF15)) and RPGR interacting protein 1 (RPGRIP1) are mutated in a variety of retinal dystrophies but their functions are poorly understood. Here, we show that in cultured mammalian cells both RPGR(ORF15) and RPGRIP1 localize to centrioles. These localizations are resistant to the microtubule destabilizing drug nocodazole and persist throughout the cell cycle. RPGR and RPGRIP1 also co-localize at basal bodies in cells with primary cilia. The C-terminal (C2) domain of RPGR(ORF15) (ORF15(C2)) is highly conserved across 13 mammalian species, suggesting that it is a functionally important domain. Using matrix-assisted laser desorption ionization time-of-flight mass spectrometry, we show that this domain interacts with a 40 kDa shuttling protein nucleophosmin (NPM). The RPGR(ORF15)-NPM interaction was confirmed by (i) yeast two-hybrid analyses; (ii) binding of both recombinant and native HeLa cell NPM to RPGR(ORF15) fusion proteins in vitro; (iii) co-immunoprecipitation of native NPM, RPGR(ORF15) and RPGRIP1 from bovine retinal extracts and of native HeLa cell NPM and transfected RPGR(ORF15) from cultured cells and (iv) co-localization of NPM and RPGR(ORF15) at metaphase centrosomes in cultured cells. NPM is a multifunctional protein chaperone that shuttles between the nucleoli and the cytoplasm and has been associated with licensing of centrosomal division. RPGR and RPGRIP1 join a growing number of centrosomal proteins involved in human disease.

Effects of high-dose selegiline on morphine reinforcement and precipitated withdrawal in dependent rats

Selegiline is an irreversible inhibitor of monoamine oxidase (MAO) with psychostimulant and neuroprotective effects. Several lines of evidence suggest that treatment with selegiline at doses that exceed levels required for inhibition of MAO can produce distinct pharmacologic effects. The purpose of this study was to evaluate the effects of chronic treatment with high-dose selegiline on extinction responding, cue-induced reinstatement, morphine reinforcement and naloxone-precipitated withdrawal. After pretreatment with noncontingent morphine to establish opiate dependence, rats acquired self-administration of 3.2 mg/kg per injection of morphine under a progressive ratio schedule. Daily treatment with saline or 6.4 mg/kg per day of selegiline was then administered over extinction, reinstatement and re-acquisition of morphine self-administration. To enhance or diminish the potential for psychostimulant effects, selegiline was administered either immediately prior to (pre-session) or 1 h following (post-session) extinction, reinstatement and self-administration sessions. Pre-session selegiline decreased the number of ratios completed on days 2, 3 and 4 of extinction, and decreased morphine self-administration during all four re-acquisition sessions. When administered at the same dose level, post-session selegiline decreased responding on the fourth extinction session, and was ineffective in modifying re-acquisition of self-administration. Selegiline administered by either schedule did not modify cue-induced reinstatement. Daily treatment with 6.4 mg/kg per day of selegiline did not modify self-administration of food under a progressive ratio schedule. Acute treatment with single, 6.4 mg/kg doses of selegiline attenuated naloxone-induced increases in ptosis and global withdrawal score, but did not modify any other sign of withdrawal or global withdrawal score calculated without ratings of ptosis. In conclusion, high-dose selegiline can attenuate extinction responding and morphine-reinforced behavior, and these effects may be mediated by psychostimulant metabolites.

The effect of platelets on fibrin gel structure formed in the presence of recombinant factor VIIa in hemophilia plasma and in plasma from a patient with Glanzmann thrombasthenia

Fibrin gel structure has been shown to be dependent on the thrombin concentration as well as the rate of thrombin generation. Accordingly, factor VIII (FVIII)- and FIX-deficient plasma (hemophilia A and B) form loose fibrin clots with high permeability constants. By adding rFVIIa in vitro to FVIII-deficient plasma containing platelets (frozen and thawed), the fibrin gel permeability constant normalized, indicating that extra rFVIIa (1.2 microg mL(-1) or higher) induced a tight fibrin structure. Thrombin generation is highly dependent on the number of platelets, and in this study it was demonstrated that the addition of rFVIIa (5 microg mL(-1)) normalizes the fibrin gel permeability in samples containing platelets (frozen-thawed) in numbers of at least down to 20 x 10(6) mL(-1). The effect of rFVIIa was not observed when unfrozen platelets instead of frozen-thawed platelets were added. Neither was any effect on the fibrin permeability seen, in the presence of annexin V, known to block the effect of phospholipids on the platelet surface. This indicates an important role of platelet phospholipids for the effect of rFVIIa. A similar effect on the fibrin permeability of rFVIIa was observed when added to platelet-rich plasma from a patient with Glanzmann thrombasthenia. Recombinant FVIIa has been found to induce hemostasis in patients with hemophilia and inhibitors against FVIII/FIX as well as in patients with Glanzmann thrombasthenia, indicating the importance of the formation of a tight fibrin gel structure, more resistant against premature proteolysis, for maintaining hemostasis. In conclusion, the addition of rFVIIa (5 microg mL(-1)) also substantially decreased the permeability constant of fibrin gels formed in FVIII-deficient plasma in the presence of low numbers of frozen-thawed platelets (down to 20 x 10(6) mL(-1)). A similar pattern was obtained in plasma from a Glanzmann patient. No effect was found in the presence of unfrozen instead of frozen-thawed platelets. Annexin V blocked any effect of rFVIIa. A normalization of the overall fibrinolysis potential (OFP) during the same condition supports the effect of rFVIIa on the fibrin permeability in the presence of a limited number of platelets.

Simultaneous nitrification and de-nitrification in MBR

Experiments have been carried out to get an understanding of the effect of DO, C/N ratio and pH on the performance of a bench scale membrane bioreactor (MBR) in simultaneous nitrification and denitrification. It was found that under the conditions of MLSS in the range of 8000-9000 mg/L and temperature of water in the MBR of 24 degrees C, influent COD and NH3-N in the range of 523-700 mg/L and 17.24-24 mg/L respectively, the removals of COD, NH3-N and TN were 98%, 99% and 60%; 96.5%, 0,98% and 75%; 96%, 95% and 92%; 90%,70% and 60% respectively at DO of 6, 3, 1 and 0.5 mg/L. It was also found that the changes in C/N ratio and pH in a certain range have a slight effect on COD removal but have significant influence on the removal of NH3-N and TN. The results showed that only under the conditions that each ecological factor was maintained relatively steadily, simultaneous nitrification and de-nitrification proceeded smoothly. It was found that when C/N ratio was 30, the influent pH 7.2, the temperature of water in MBR 24 degrees C and DO 1 mg/L, as optimum conditions, the removals of COD, NH3-N and TN were 96%, 95% and 92% respectively. In addition, mechanism research on simultaneous nitrification and de-nitrification in MBR has been conducted as well.

105 EXPRESSION OF PLURIPOTENCY-DETERMINING FACTORS Oct-4 AND NANOG IN PRE-IMPLANTATION GOAT EMBRYOS

The objective of this study was to determine the expression patterns of the pluripotency-determining factors, Oct-4 and Nanog, in pre-implantation goat embryos. The POU octamer-binding domain transcription factor Oct-4 and the homeobox transcription factor Nanog have been shown to play key roles in the maintenance of pluripotency in the inner cell mass (ICM) of pre-implantation mouse embryos and in embryonic stem cells. As Oct-4 protein has been observed in human, monkey, bovine, and porcine pre-implantation embryos, its role in embryonic development and differentiation may be conserved across these species. The patterns of mRNA expression for Oct-4 and Nanog have not been reported for ruminant embryos. In this study, total RNA was extracted from 10 in vivo-derived goat embryos at each stage (8-cell, morula, and blastocyst) using an Absolutely RNA Nanoprep Kit (Stratagene, La Jolla, CA, USA). The first-strand cDNAs were synthesized using Superscript III (Invitrogen, Carlsbad, CA, USA) and cDNAs were amplified with PfuUltra hotstart PCR master mix (Stratagene). Oct-4 primers were designed based on bovine Oct-4 open-reading sequence, while Nanog primers were designed based on the human Nanog open-reading sequence. Expression screening by PCR was performed. Oct-4 mRNA expression was detected at the 8-cell, morula and blastocyst stages. Sequencing of the 1.1-kb PCR product with Oct-4 primers revealed 87% homology to human cDNA sequence and 96% homology to the bovine sequence. Protein localization of Oct-4 as observed by immunocytochemistry was diffuse at the morula stage, but moved to a more nuclear location at the blastocyst stage. Oct-4 protein and mRNA expression were detected in both the ICM and trophectoderm of expanded blastocysts. This pattern of protein expression is similar to that reported by others in the pig and cow. As caprine, bovine, and porcine embryos all show extensive proliferation and elongation of the trophectoderm, continued expression of Oct-4 protein in the trophectoderm may be necessary to prevent premature differentiation of the trophectoderm. Nanog mRNA was detected at the morula and blastocyst stages. Nanog mRNA was detected in the ICM but not the trophectoderm of expanded goat blastocysts, a pattern that follows the expression observed in mice. Sequencing of the 698 bp PCR product obtained by RT-PCR from goat blastocysts confirmed that the mRNA detected was Nanog. Sequence alignment (ClustalW) showed that the cDNA sequence identities were 96% between goat and human and 70% between goat and mouse. The amino acid identities were 93% between goat and human and 52% between goat and mouse. To our knowledge this is the first report of detection of Nanog in domestic animals. These results are supportive of the premise that core components involved in the control of pluripotency are analogous across vertebrate species.