Rapid and widespread suppression of self-renewal by microRNA-203 during epidermal differentiation.

MicroRNAs (miRNAs) play important roles in differentiation of stem cells. However, the precise dynamics of miRNA induction during stem cell differentiation have not been visualized and molecular mechanisms through which miRNAs execute their function remain unclear. Using high-resolution in situ hybridization together with cell lineage and proliferation markers in mouse skin, we show that miR-203 is transcriptionally activated in the differentiating daughter cells upon the asymmetric cell division of interfollicular progenitor cells. Once induced, miR-203 rapidly promotes the cell cycle exit within 6 hours and abolishes self-renewal of the progenitor cells. With an inducible mouse model, we identify numerous miR-203 in vivo targets that are highly enriched in regulation of cell cycle and cell division, as well as in response to DNA damage. Importantly, co-suppression of individual targets, including p63, Skp2 and Msi2 by miR-203 is required for its function of promoting the cell cycle exit and inhibiting the long-term proliferation. Together, our findings reveal the rapid and widespread impact of miR-203 on the self-renewal program and provide mechanistic insights into the potent role of miR-203 during the epidermal differentiation. These results should also contribute to understanding the role of miR-203 in the development of skin cancer.

Compromised mitochondrial fatty acid synthesis in transgenic mice results in defective protein lipoylation and energy disequilibrium.

A mouse model with compromised mitochondrial fatty acid synthesis has been engineered in order to assess the role of this pathway in mitochondrial function and overall health. Reduction in the expression of mitochondrial malonyl CoA-acyl carrier protein transacylase, a key enzyme in the pathway encoded by the nuclear Mcat gene, was achieved to varying extents in all examined tissues employing tamoxifen-inducible Cre-lox technology. Although affected mice consumed more food than control animals, they failed to gain weight, were less physically active, suffered from loss of white adipose tissue, reduced muscle strength, kyphosis, alopecia, hypothermia and shortened lifespan. The Mcat-deficient phenotype is attributed primarily to reduced synthesis, in several tissues, of the octanoyl precursors required for the posttranslational lipoylation of pyruvate and α-ketoglutarate dehydrogenase complexes, resulting in diminished capacity of the citric acid cycle and disruption of energy metabolism. The presence of an alternative lipoylation pathway that utilizes exogenous free lipoate appears restricted to liver and alone is insufficient for preservation of normal energy metabolism. Thus, de novo synthesis of precursors for the protein lipoylation pathway plays a vital role in maintenance of mitochondrial function and overall vigor.

Oxidative stress in rat striatum after pilocarpine-induced seizures is diminished by alpha-tocopherol.

Alpha-tocopherol has numerous nonenzymatic actions and is a powerful liposoluble antioxidant. The objective of the present study was to evaluate the neuroprotective effects of alpha-tocopherol in rats against oxidative stress caused by pilocarpine-induced seizures. Wistar rats were intraperitoneally treated with 0.9% saline (control group), alpha-tocopherol (200 mg/kg, alpha-tocopherol group), pilocarpine (400 mg/kg, pilocarpine group), or the combination of alpha-tocopherol (200 mg/kg) and pilocarpine (400 mg/kg, i.p.; alpha-tocopherol plus pilocarpine group). After the treatments, all groups were observed for 24 h. The superoxide dismutase (Mn-SOD) and catalase activities, lipid peroxidation and nitrite concentrations were measured using spectrophotometrically methods. To clarify the mechanism of alpha-tocopherol on oxidative stress in pilocarpine model, Western blot analysis of Mn-SOD and catalase in rat striatum were performed. In the pilocarpine group, rats showed a significant increase in lipid peroxidation and nitrite levels. However, there were no alterations on Mn-SOD activity. On the other hand, the catalase activity augmented in pilocarpine group. In the alpha-tocopherol and pilocarpine co-administered rats, antioxidant treatment significantly reduced the lipid peroxidation level and nitrite content and increased the Mn-SOD and catalase activities in rat striatum after seizures. Pilocarpine, alpha-tocopherol plus pilocarpine and alpha-tocopherol groups did not affect of the Mn-SOD and catalase mRNA or protein levels. Our findings strongly support the hypothesis that oxidative stress occurs in striatum during pilocarpine-induced seizures, indicating that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences, which implies that strong protective effect could be achieved using alpha-tocopherol.

Antioxidant mechanisms of iso-6-cassine in suppressing seizures induced by pilocarpine

The aim of this study was to evaluate the in vitro antioxidant effects of 12-[(2R,5R,6R)-5-hydroxy-6-methylpiperidin-2-yl]dodecan-2-one (iso-6-cassine; ISO) and the anticonvulsant effects of ISO on pilocarpine-induced seizures in rats. Wistar rats were treated with 0.9 percent saline (i.p., control group), pilocarpine (400 mg/kg, i.p., pilocarpine group), and the association of ISO (1.0 mg/kg, i.p.) plus pilocarpine (400 mg/kg, i.p.), 30 min after administration of ISO (ISO plus pilocarpine group). After the treatments all groups were observed for 1h. The antioxidant effect of ISO on the pilocarpine model was assessed by determining the activity of glutathione peroxidase (GPx), glutathione-S-transferase (GST) and catalase (CAT) as well as the levels of reactive species (RS) and lipid peroxidation (LP). In vitro, ISO (5 μM) reduced RS and LP. ISO (1.0 mg/kg) and abolished seizures and death induced by pilocarpine in rats. ISO protected against the increase in the RS and LP levels, GST activity as well as the inhibition of GPx activity caused by pilocarpine. In addition, ISO increased the catalase activity in hippocampus of seized rats. In conclusion, the dta suggest that ISO can present anticonvulsant and antioxidant properties in the pilocarpine model of seizures in rats.

Evaluation of central nervous system effects of iso-6-cassine isolated from Senna spectabilis var. excelsa (Schrad) in mice.

The depressant and anticonvulsant activities of iso-6-cassine (ISO) from Senna spectabilis (0.5, 1.0 and 1.5mg/kg) injected by oral route in mice caused a significant decrease in the motor activity of animals when compared with the control group, up to 30 days after the administration and at dose of 1.5mg/kg, it reduced the remaining time of animals on Rota-rod apparatus. Additionally, ISO at doses tested was also capable to promote an increase of latency for development of convulsions induced by pentylenetetrazole and picrotoxin. These results suggest possible depressant and anticonvulsant activities in mice that need further investigation.

Caffeic acid effects on oxidative stress in rat hippocampus after pilocarpine-induced seizures.

The objective of the study was to evaluate the caffeic acid (CA) effects against the oxidative stress (OS) observed during seizures. Wistar rats were intraperitoneally treated with either 0.9% saline (control), CA (4 mg/kg), pilocarpine (400 mg/kg, pilocarpine group), or the association of CA (4 mg/kg) plus pilocarpine (400 mg/kg). The thiobarbituric-acid-reacting substances and the hippocampal nitrite content were significantly increased (89 and 94%, respectively) in pilocarpine group when compared with control. There were marked decreases in lipid peroxidation level (43%) and nitrite content (45%) in CA group when compared with pilocarpine group. There were no marked alterations in superoxide dismutase (SOD) and catalase (CAT) activities in pilocarpine group; however, the SOD and CAT activities were significantly increased (35 and 51%, respectively) after CA pretreatment. Our findings strongly support the hypothesis that OS was indeed generated in hippocampus. CA pretreatment can reduces the OS produced by seizures.

Neuropharmacological effects of lipoic acid and ubiquinone on δ-aminolevulinic dehydratase, Na(+) , K(+) -ATPase, and Mg(2+) -ATPase activities in rat hippocampus after pilocarpine-induced seizures.

UNLABELLED: In this study, we investigated the effects of lipoic acid (LA) in the hippocampus oxidative stress caused by pilocarpine-induced seizures in adult rats. Wistar rats were treated with 0.9% saline (i.p., control group), LA (10mg/kg, i.p., LA group), ubiquinone [20mg/kg, i.p., ubiquinone (UQ) group], pilocarpine (400mg/kg, i.p., P400 group), and the association of LA (10mg/kg, i.p.) plus pilocarpine (400mg/kg, i.p.) or UQ (20mg/kg, i.p.) plus pilocarpine (400mg/kg, i.p.), 30min before of administration of P400 (LA plus P400 group and UQ plus P400 group, respectively). After the treatments, all groups were observed for 1h. The enzyme activities (δ-aminolevulinic dehydratase (δ-ALA-D), Mg(2+) -ATPase, and Na(+) , K(+) -ATPase) were measured using spectrophotometric methods, and the results compared to values obtained from saline and pilocarpine-treated animals. Protective effects of LA and UQ were also evaluated on the same parameters. We reported here for the first time that Na(+) , K(+) -ATPase and δ-ALA-D activities inhibition and Mg(2+) -ATPase stimulation in the pilocarpine model are probably attributed to the oxidative stress caused by seizures in the rat hippocampus. The addition of the antioxidants LA and UQ may reverses the previously mentioned Na(+) , K(+) -ATPase and δ-ALA-D inhibitions and Mg(2+) -ATPase stimulation. CONCLUSIONS: The oxidative stress plays an important signaling role in pilocarpine-induced seizures, and antioxidant drugs might be considered as therapeutical tools in this pathology.

Lipoic acid inhibits caspase-dependent and -independent cell death pathways and is neuroprotective against hippocampal damage after pilocarpine-induced seizures.

Alpha-lipoic acid has some neuroprotective properties, but this action has not been investigated in models of epilepsy. The aim of the present study was to investigate the protective efficacy of α-lipoic acid (lipoic acid) against pilocarpine-induced cell death through the caspase-dependent or -independent mitochondrial apoptotic pathways. Wistar rats were injected intraperitoneally with 0.9% saline (control group), pilocarpine (400 mg/kg, pilocarpine group) alone, or α-lipoic acid (20 mg/kg) in association with pilocarpine (400 mg/kg) 30 min before administration of α-lipoic acid. After the treatments all groups were observed for 24 h. Cell death was reduced in lipoic acid-treated rats. Cytosolic translocation of cytochrome c and subsequent activation of caspase-3 were reduced by lipoic acid treatment. AIF nuclear translocation and subsequent large-scale DNA fragmentation were also decreased in lipoic acid-treated rats. Our study suggests that lipoic acid inhibits both caspase-dependent and -independent apoptotic pathways and may be neuroprotective against hippocampal damage during pilocarpine-induced seizures.

The effects of alpha-tocopherol on hippocampal oxidative stress prior to in pilocarpine-induced seizures.

Reactive oxygen species have been implicated in seizure-induced neurodegeneration, and there is a correlation between free radical level and scavenger enzymatic activity in the epilepsy. It has been suggested that pilocarpine-induced seizures is mediated by an increase in oxidative stress. Current research has found that antioxidant may provide, in a certain degree, neuroprotection against the neurotoxicity of seizures at the cellular level. Alpha-tocopherol has numerous nonenzymatic actions and is a powerful liposoluble antioxidant. The objective of the present study was to evaluate the neuroprotective effects of alpha-tocopherol (TP) in rats, against oxidative stress caused by pilocarpine-induced seizures. 30 min prior to behavioral observation, Wistar rats were treated with, 0.9% saline (i.p., control group), TP (200 mg/kg, i.p., TP group), pilocarpine (400 mg/kg, i.p., P400 group), or the combination of TP (200 mg/kg, i.p.) and pilocarpine (400 mg/kg, i.p.). After the treatments all groups were observed for 6 h. The enzymatic activities, lipid peroxidation and nitrite concentrations were measured using speccitrophotometric methods and these data were assayed. In P400 group mice there was a significant increase in lipid peroxidation and nitrite levels. However, no alteration was observed in superoxide dismutase (SOD) and catalase activities. In the TP and pilocarpine co-administered mice, antioxidant treatment significantly reduced the lipid peroxidation level and nitrite content, as well as increased the SOD and catalase activities in rat hippocampus after seizures. Our findings strongly support the hypothesis that oxidative stress occurs in hippocampus during pilocarpine-induced seizures, indicate that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences, and imply that strong protective effect could be achieved using alpha-tocopherol.

Effects of ubiquinone on hydroperoxide concentration and antioxidant enzymatic activities in the rat hippocampus during pilocarpine-induced seizures.

Recent researches have shown that antioxidant compounds may have certain neuroprotective effect against the neurotoxicity of seizures at cellular level. Ubiquinone (UQ), an antioxidant compound, exhibits a wide range of therapeutic effects that are attributed to its potent antioxidant capacity. The objective of the present study was to evaluate the neuroprotective effects of UQ in rats, against the observed oxidative stress during seizures induced by pilocarpine. Wistar rats were treated with either 0.9% saline (i.p., control group), UQ (5, 10 or 20 mg/kg, i.p., UQ5, UQ10 and UQ20 groups), pilocarpine (400 mg/kg, i.p., P400 group), or co-administration of pilocarpine with UQ group rats 30 min prior to UQ administration. After the treatments all groups were observed for 24 h. The antioxidant enzymatic activities as well as the hydroperoxide concentrations were measured using spectrophotometric methods and the results were analyzed. In pilocarpine group there was a significant increase in hydroperoxides concentration and glutathione peroxidase activity. However, no alteration was observed in superoxide dismutase and catalase activities. Antioxidant treatment significantly reduced the hydroperoxide content and increased the superoxide dismutase, catalase and glutathione peroxidase activities in rat hippocampus during seizures induced by pilocarpine. Our findings strongly support the hypothesis that oxidative stress in hippocampus occurs during seizures induced by pilocarpine, which indicates that brain damage induced by the oxidative process plays a crucial role in seizures pathogenic consequences. Our result also suggests that ubiquinone can exert significant neuroprotective effects that might be useful in the treatment of neurodegenerative diseases.

Lipoic acid blocks seizures induced by pilocarpine via increases in delta-aminolevulinic dehydratase and Na+, K+-ATPase activity in rat brain.

In the present study we investigated the effects of lipoic acid (LA) on delta-aminolevulinic dehydratase (delta-ALA-D) and Na(+), K(+)-ATPase activities in rat brain after seizures induction by pilocarpine. Wistar rats were treated with 0.9% saline (i.p., control group), lipoic acid (10mg/kg, i.p., LA group), pilocarpine (400mg/kg, i.p., pilocarpine group), or the combination of LA (10mg/kg, i.p.) with pilocarpine (400mg/kg, i.p.), 30 min before administration of LA (LA plus pilocarpine group). After the treatments all groups were observed for 1h. The enzyme activities (delta-ALA-D and Na(+), K(+)-ATPase) were measured using spectrophotometric methods, and the results were compared with that obtained from saline and pilocarpine-treated animals. Neuroprotective effects of LA against seizures were evaluated based on those enzyme activities. The pilocarpine group showed a reduction in delta-ALA-D and Na(+), K(+)-ATPase activities after seizures. In turn, LA plus pilocarpine abolished the appearance of seizures and reversed the decreased in delta-ALA-D and Na(+), K(+)-ATPase activities produced by seizures, when compared to the pilocarpine seizing group. The results from the present study demonstrate that preadministration of LA abolished seizure episodes induced by pilocarpine in rat, probably by increasing delta-ALA-D and Na(+), K(+)-ATPase activities in rat brain during seizures.

Down-regulation of mitochondrial acyl carrier protein in mammalian cells compromises protein lipoylation and respiratory complex I and results in cell death.

The objective of this study was to evaluate the physiological importance of the mitochondrial fatty acid synthesis pathway in mammalian cells using the RNA interference strategy. Transfection of HEK293T cells with small interfering RNAs targeting the acyl carrier protein (ACP) component reduced ACP mRNA and protein levels by >85% within 24 h. The earliest phenotypic changes observed were a marked decrease in the proportion of post-translationally lipoylated mitochondrial proteins recognized by anti-lipoate antibodies and a reduction in their catalytic activity, and a slowing of the cell growth rate. Later effects observed included a reduction in the specific activity of respiratory complex I, lowered mitochondrial membrane potential, the development of cytoplasmic membrane blebs containing high levels of reactive oxygen species and ultimately, cell death. Supplementation of the culture medium with lipoic acid offered some protection against oxidative damage but did not reverse the protein lipoylation defect. These observations are consistent with a dual role for ACP in mammalian mitochondrial function. First, as a key component of the mitochondrial fatty acid biosynthetic pathway, ACP plays an essential role in providing the octanoyl-ACP precursor required for the protein lipoylation pathway. Second, as one of the subunits of complex I, ACP is required for the efficient functioning of the electron transport chain and maintenance of normal mitochondrial membrane potential.

The transmembrane domain is sufficient for Sbh1p function, its association with the Sec61 complex, and interaction with Rtn1p.

The Sec61 protein translocation complex in the endoplasmic reticulum (ER) membrane is composed of three subunits. The alpha-subunit, called Sec61p in yeast, is a multispanning membrane protein that forms the protein conducting channel. The functions of the smaller, carboxyl-terminally tail-anchored beta subunit Sbh1p, its close homologue Sbh2p, and the gamma subunit Sss1p are not well understood. Here we show that co-translational protein translocation into the ER is reduced in sbh1Delta sbh2Delta cells, whereas there is a limited reduction of post-translational translocation and no effect on export of a mutant form of alpha-factor precursor for ER-associated degradation in the cytosol. The translocation defect and the temperature-sensitive growth phenotype of sbh1Delta sbh2Delta cells were rescued by expression of the transmembrane domain of Sbh1p alone, and the Sbh1p transmembrane domain was sufficient for coimmunoprecipitation with Sec61p and Sss1p. Furthermore, we show that Sbh1p co-precipitates with the ER transmembrane protein Rtn1p. Sbh1p-Rtn1p complexes do not appear to contain Sss1p and Sec61p. Our results define the transmembrane domain as the minimal functional domain of the Sec61beta homologue Sbh1p in ER translocation, identify a novel interaction partner for Shb1p, and imply that Sbh1p has additional functions that are not directly linked to protein translocation in association with the Sec61 complex.

Characterization of GPI14/YJR013w mutation that induces the cell wall integrity signalling pathway and results in increased protein production in Saccharomyces cerevisiae.

We report here identification and characterization of a mutation in the GPI14 gene, the yeast homologue of the mammalian PIG-M that functions in the synthesis of the GPI moiety anchoring proteins to the plasma membrane. We show that the first putative transmembrane domain of Gpi14p is not essential for its function. Downregulation of GPI14 expression/reduced protein function due to an amino terminal deletion resulted in increased transcription and production of an endogenous and a heterologous secreted protein expressed from HSP150 and ADH1 promoter, respectively. In these cells, unfolded protein response was induced but was not responsible for the enhanced production of these proteins. A cell wall defect in the gpi14 mutant cells was suggested by cell aggregation phenotype, increased sensitivity to Calcofluor white, an increased release of Gas1p and total protein into the culture medium. In the gpi14 mutant cells, transcription of RLM1, a transcription factor participating in the cell wall integrity signalling pathway, was increased, and deletion of RLM1 resulted in a synthetic lethal phenotype with the gpi14 mutation. These results suggest that partial inactivation of Gpi14p causes defects in the cell wall structure and suggest that compromised GPI anchor synthesis results in enhanced protein production via the cell wall integrity signalling pathway.

Molecular interactions position Mso1p, a novel PTB domain homologue, in the interface of the exocyst complex and the exocytic SNARE machinery in yeast.

In this study, we have analyzed the association of the Sec1p interacting protein Mso1p with the membrane fusion machinery in yeast. We show that Mso1p is essential for vesicle fusion during prospore membrane formation. Green fluorescent protein-tagged Mso1p localizes to the sites of exocytosis and at the site of prospore membrane formation. In vivo and in vitro experiments identified a short amino-terminal sequence in Mso1p that mediates its interaction with Sec1p and is needed for vesicle fusion. A point mutation, T47A, within the Sec1p-binding domain abolishes Mso1p functionality in vivo, and mso1T47A mutant cells display specific genetic interactions with sec1 mutants. Mso1p coimmunoprecipitates with Sec1p, Sso1/2p, Snc1/2p, Sec9p, and the exocyst complex subunit Sec15p. In sec4-8 and SEC4I133 mutant cells, association of Mso1p with Sso1/2p, Snc1/2p, and Sec9p is affected, whereas interaction with Sec1p persists. Furthermore, in SEC4I133 cells the dominant negative Sec4I133p coimmunoprecipitates with Mso1p-Sec1p complex. Finally, we identify Mso1p as a homologue of the PTB binding domain of the mammalian Sec1p binding Mint proteins. These results position Mso1p in the interface of the exocyst complex, Sec4p, and the SNARE machinery, and reveal a novel layer of molecular conservation in the exocytosis machinery.

[Post-transcriptional gene silencing--a plant defense strategy to viruses invasion].

Gene silencing is a kind of epigenetic phenomenon discovered in transgenic plants in recent years. Gene silencing can be divided into two types: position effect and homology dependent gene silencing (HdGS). Homology-dependent gene silencing (HdGS), which is the generic term for transcriptional gene silencing (TGS), post-transcriptional gene silencing (PTGS) and RNA-mediated virus-resistance (RmVR) have been shown to frequently occur in transgenic plants. Post-transcriptional gene silencing (PTGS) is an antiviral defense system of plants, which has led to a new understanding of the relationship between viruses and plants. And it's a co-evolution result between plants and viruses. A few hypothesis models have been proposed to elucidate the mechanism of gene silencing, but they could not explain all the phenomena in gene silencing. In this paper, we reviewed the relationship between PTGS and the plants defense mechanism to virus, and proposed a model of gene silencing based on our experiments results.

The expression of tga1a gene from tobacco affects the expression of exogenous gene in transgenic plant.

The DNA-binding protein TGA1a of tobacco can specially interact with the enhancer sequence as-1 (-83 to-63) of CaMV35S promoter and show the function of transcriptional activation. In order to study the expression of exogenous gene affected by TGA1a, a trans-acting regulation system was formed by tandem connecting tga1a under the control of the phloem-specific promoter rolC with reporter gene under the control of CaMV35S. Then, the system above was utilized to construct a plant expression vector. Moreover, two plant expression vectors were constructed with the report gene controlled by CaMV35S and rolC promoter respectively as positive controls. Tobacco leaf disc transformed by Agrobacterium-mediated method and transgenic plants were regenerated. It was proved that the reporter gene existed in the genome of transgenic plants by Southern hybridization. The results of GUS activity indicated that the expression of tga1a controlled by rolC remarkably increased the expression of the reporter gene controlled by CaMV35S. GUS activity of transgenic plants containing trans-acting regulation system was higher than that of transgenic plants containing the reporter gene under the control of CaMV35S and rolC respectively, with the highest GUS activity of about tenfolds of two positive controls. Histochemical method demonstrated that GUS staining amassed mainly in phloem tissue of transgenic plants containing the trans-acting regulation system. A new model for arising the expression level and tissue-specific expression of exogenous gene in transgenic plant was established in this study.

The first intron of rice EPSP synthase enhances expression of foreign gene.

The first intron (EPI) of rice 5-enolpyruvylshikimate 3-phosphate synthase gene was isolated by PCR from one clone with genomic EPSP synthase gene. Sequence analysis showed that the first intron is 704 bp in length with 36.2% G+C content. To investigate its effect on expression of foreign gene, we inserted the first intron between CaMV35S promoter and beta-glucuronidase (GUS) gene. The transient expression results showed that GUS could be expressed effectively with EPI. The GUS activity in transgenic tobacco shows that the EPI can greatly enhance the expression level of beta-glucuronidase (P < 0.01) compared with transgenic tobacco without the first intron, and 3-to 6-fold increase in GUS activity in some transgenic tobaccos. Northern blot indicated the first intron was spliced from GUS pre-mRNA, and the steady-state mRNA levels of GUS with EPI in transgenic tobaccos were higher than that in transgenic tobacco without EPI, which suggested that the first intron of EPSP was a non-translated intron.

[Relativity betweeen expression level of potato virus X coat protein and the codon usage of wobble codon].

The relationship between the quantities of rare codons and the expression levels of foreign genes is very important in gene engineering. But up to now, there is few experiment on it in multi-cellular eukaryotes, especially in plants. To study the effect of rare codons on the expression level of potato virus X (PVX) coat protein (CP) in transgenic tobacco, some preferred codons in PVX coat protein gene were substituted with synonymous rare codons without changing the encoded amino acid sequence using site-specific mutation. The modified coat protein gene (cpm) and non-modified coat protein gene (cpw) were inserted into binary vector under the control of CaMV35S promoter, and these two plant expression constructs were transferred into tobacco (Nicotiana tabacum cv. Xanthi) genomes via Agrobacterium mediated method and transgenic plants were generated. Western blot and ELISA of these transgenic tobaccos showed that the expression level of modified CP is about one third to one sixth of that of non-modified CP. Northern blot analysis of RNAs from some transformants indicated that the transcriptional levels of cpm are the same as that of cpw, which implicated that the quantity of rare codons in foreign gene was a possible limited factor in foreign gene expression process. Changing the quantity of rare codons maybe an effective method for organism to control gene expression.

[Anther culture generated stem borer-resistance DH lines of Minghui 81(Oryza sativa L. subsp. indica) expressing modified cry1Ac gene].

2600 Anthers from T0 modified cry1 Ac-transgenic rice lines of Minghui 81, an elite restoring line of commercial CMS indica hybrid rice, were cultured on SK3 media. 83 green plantlets were recovered, 43 double haploid (DH) and 40 haploid among them. Results of PCR analyzes indicated that 55 plants of 83 were harbored the cry1Ac gene, and the ratio of cry1Ac-positive against cry1Ac-negative was 2:1 (55/28). 36 putative transgenic DH plants were further confirmed by Southern blot. ELISA detection showed that Cry1Ac level in different transgenic rice plants of the same cry1Ac-DH clone was almost equal and the highest one amount to 0.25% of the total soluble protein. Pest insect-resistant bioassay at field trials demonstrated that some of the homozygous cry1Ac-transgenic rice plants not only showed high-level resistance against striped stem borer (Chilo suppressalis) but also retained elite agronomy characters. These results demonstrated that rice anther culture has a great value in rice molecular breeding.