The influence of a polymorphism at position -857 of the tumour necrosis factor gene on clinical response to etanercept therapy in rheumatoid arthritis

OBJECTIVES

We aimed to test whether polymorphisms in the etanercept target genes TNFA and LTA are associated with clinical responses to etanercept therapy in RA patients.

METHODS

Clinical responses of 70 patients treated with etanercept were determined according to the ACR criteria. We genotyped 13 single-nucleotide polymorphisms (SNPs) within TNFA and LTA and tested whether they influenced the responses to 12 weeks of etanercept therapy. Univariate and multivariate analyses were performed to compare allele, genotype and haplotype distributions between responders and non-responders.

RESULTS

Association of the -857C/T SNP at the TNFA promoter was marginally significant when patients were divided into responders and non-responders according to improvement criteria ACR20 or ACR70. When ACR70 responders (the best responders) were compared with ACR20 non-responders (the worst responders), however, the association was prominent [odds ratio (OR) = 12, 95% confidence interval (CI) = 1.4-105, P = 0.0077, P(corrected) = 0.054], as the frequency of the T allele was 5% in the ACR20 non-responders but 39% in the ACR70 responders. Moreover, the ratio of ACR70 responder number to ACR20 non-responder number among T-allele carriers was >10-fold higher than in the C-allele homozygotes (OR = 12, 95% CI = 1.2-120, P = 0.033).

CONCLUSIONS

RA patients with the T allele of TNFA -857C/T SNP respond better to etanercept therapy than homozygotes for the C allele, indicating that, when the results have been confirmed, this SNP could become a useful genetic marker for predicting responses.

Activity of a synthetic hexadecasaccharide (SanOrg123781A) in a pig model of arterial thrombosis

The activity of SanOrg123781A, a new synthetic antithrombotic drug inhibiting both factor Xa and thrombin through antithrombin (AT), was compared to that of unfractionated heparin (UFH) and of the synthetic pentasaccharide (fondaparinux, SP) in an ex vivo arterial thrombosis model in the pig. Six groups of four pigs were administered intravenously with SanOrg123781A (1, 3, 10 and 30 nmol kg(-1)), UFH (30 nmol kg(-1)) or SP (30 nmol kg(-1)). In this arterial model in which platelet thrombus was formed on a thrombogenic surface under a constant high shear rate, UFH and SP had moderate antithrombotic effects while SanOrg123781A exhibited a strong, dose-dependent inhibitory activity on platelet adhesion and platelet thrombus formation. In contrast to UFH, SanOrg123781A did not modify the activated partial thromboplastin time (aPTT) even at 30 nmol kg(-1), but strongly inhibited thrombin generation. At the same dose, despite a lower antithrombotic activity than SanOrg123781A, UFH significantly affected all the coagulation parameters. Taken together, these results show that SanOrg123781A, due to its potent and selective antifactor Xa and antifactor IIa activities is a promising new antithrombotic agent even in arterial setting.

Pathogenesis of and immunity to a new influenza A (H5N1) virus isolated from duck meat

The outbreak of avian influenza H5N1 in Hong Kong in 1997 raised concerns about the potential for the H5 subtype to cause a human pandemic. In 2001 a new H5N1 virus, A/Duck Meat/Anyang/AVL-1/2001 (A/Dkmt), was isolated from imported duck meat in Korea. The pathogenesis of this virus was investigated in mice. A/Dkmt virus had low infectivity but was lethal for mice at high doses, and at lethal doses, the virus replicated in the brains of infected mice. A/Dkmt virus cross-reacted poorly with ferret antisera raised against human H5N1 viruses, but prior infection with A/Dkmt virus protected mice from death after secondary infection with human H5N1 virus.

Pathogenicity and antigenicity of a new influenza A (H5N1) virus isolated from duck meat

Avian influenza A viruses are the ancestral origin of all human influenza viruses. The outbreak of highly pathogenic (HP) avian H5N1 in Hong Kong in 1997 highlighted the potential of these viruses to infect and cause severe disease in humans. Since 1999, HP H5N1 viruses were isolated several times from domestic poultry in Asia. In 2001, a HP H5N1 virus, A/Duck/Anyang/AVL-1/2001 (Dk/Anyang), was isolated from imported frozen duck meat in Korea. Because of this novel source of HP H5N1 virus isolation, concerns were raised about the potential for human exposure and infection; we therefore compared the Dk/Anyang virus with HP H5N1 viruses isolated from humans in 1997 in terms of antigenicity and pathogenicity for mammals. At high doses, Dk/Anyang virus caused up to 50% mortality in BALB/c mice, was isolated from the brains and lymphoid organs of mice, and caused lymphopenia. Overall Dk/Anyang virus was substantially less pathogenic for mice than the H5N1 virus isolated from a fatal human case in 1997. Likewise, Dk/Anyang virus was apathogenic for ferrets. Dk/Anyang virus was antigenically distinguishable by hemagglutination-inhibition (HI) assay from human H5N1 viruses isolated in 1997 and avian H5N1 viruses isolated in 2001 in Hong Kong. Nevertheless, prior infection with Dk/Anyang virus protected mice from death after secondary infection with HP human H5N1 viruses. These results indicate that compared with HP human H5N1 viruses, Dk/Anyang virus is substantially less pathogenic for mammalian species. Nevertheless, the novel source of isolation of this avian H5N1 virus must be considered when evaluating the potential risk to public health.

Intrinsically disordered protein

Proteins can exist in a trinity of structures: the ordered state, the molten globule, and the random coil. The five following examples suggest that native protein structure can correspond to any of the three states (not just the ordered state) and that protein function can arise from any of the three states and their transitions. (1) In a process that likely mimics infection, fd phage converts from the ordered into the disordered molten globular state. (2) Nucleosome hyperacetylation is crucial to DNA replication and transcription; this chemical modification greatly increases the net negative charge of the nucleosome core particle. We propose that the increased charge imbalance promotes its conversion to a much less rigid form. (3) Clusterin contains an ordered domain and also a native molten globular region. The molten globular domain likely functions as a proteinaceous detergent for cell remodeling and removal of apoptotic debris. (4) In a critical signaling event, a helix in calcineurin becomes bound and surrounded by calmodulin, thereby turning on calcineurin's serine/threonine phosphatase activity. Locating the calcineurin helix within a region of disorder is essential for enabling calmodulin to surround its target upon binding. (5) Calsequestrin regulates calcium levels in the sarcoplasmic reticulum by binding approximately 50 ions/molecule. Disordered polyanion tails at the carboxy terminus bind many of these calcium ions, perhaps without adopting a unique structure. In addition to these examples, we will discuss 16 more proteins with native disorder. These disordered regions include molecular recognition domains, protein folding inhibitors, flexible linkers, entropic springs, entropic clocks, and entropic bristles. Motivated by such examples of intrinsic disorder, we are studying the relationships between amino acid sequence and order/disorder, and from this information we are predicting intrinsic order/disorder from amino acid sequence. The sequence-structure relationships indicate that disorder is an encoded property, and the predictions strongly suggest that proteins in nature are much richer in intrinsic disorder than are those in the Protein Data Bank. Recent predictions on 29 genomes indicate that proteins from eucaryotes apparently have more intrinsic disorder than those from either bacteria or archaea, with typically > 30% of eucaryotic proteins having disordered regions of length > or = 50 consecutive residues.

Sequence analysis of hemagglutinin and nucleoprotein genes of measles viruses isolated in Korea during the 2000 epidemic

To characterize the genetic properties of currently circulating measles viruses in Korea, the complete nucleotide sequences of hemagglutinin (H) protein and nucleoprotein (N) genes of Korean viruses were analyzed. The entire genes of H and N were directly amplified by RT-PCR from each clinical specimen and sequenced. Sequence analyses of H and N genes indicated that all Korean viruses had a high degree of homology (>99.8%) when compared with each other. The Korean viruses differed from other wild-type viruses by as much as 6.8% in the H gene and 6.5% in the N gene at the nucleotide level. The deduced amino acid variability was up to 6.4% for the H protein and up to 6.5% for the N protein. Phylogenetic analyses of nucleotide sequences and deduced amino acid sequences of the H and N genes revealed that all Korean viruses were grouped into the clade H1.

FADD-deficient T cells exhibit a disaccord in regulation of the cell cycle machinery

FADD is an adapter protein that was originally isolated as a transducer of apoptotic signals for death domain-containing receptors. However, FADD-deficient mice are embryonic lethal and FADD(-/-) T cells developed from FADD(-/-) embryonic stem cells in the RAG-1(-/-) hosts lack the full potential to proliferate when stimulated through their T-cell receptor complex, suggesting that FADD protein might play a dualistic role in mediating not only cell death signaling but other non-apoptotic cellular pathways as well. Here we show that a substantial number of freshly isolated FADD(-/-) peripheral T cells are cycling but are defective in their co-stimulatory response when stimulated. Analysis of several cell cycle proteins shows normal down-regulation of p27 inhibitor but increased levels of p21, decreased levels of cyclin D2, and constitutive activation of several cyclin-dependent kinases in activated T cells. These data suggest that FADD is involved in the regulation of cell cycle machinery in T lymphocytes.

Drosophila Med6 is required for elevated expression of a large but distinct set of developmentally regulated genes

Mediator is the evolutionarily conserved coactivator required for the integration and recruitment of diverse regulatory signals to basal transcription machinery. To elucidate the functions of metazoan Mediator, we isolated Drosophila melanogaster Med6 mutants. dMed6 is essential for viability and/or proliferation of most cells. dMed6 mutants failed to pupate and died in the third larval instar with severe proliferation defects in imaginal discs and other larval mitotic cells. cDNA microarray, quantitative reverse transcription-PCR, and in situ expression analyses of developmentally regulated genes in dMed6 mutants showed that transcriptional activation of many, but not all, genes was affected. Among the genes found to be affected were some that play a role in cell proliferation and metabolism. Therefore, dMed6 is required in most cells for transcriptional regulation of many genes important for diverse aspects of Drosophila development.

T cell-specific FADD-deficient mice: FADD is required for early T cell development

FADD/Mort1, initially identified as a Fas-associated death-domain containing protein, functions as an adapter molecule in apoptosis initiated by Fas, tumor necrosis factor receptor-I, DR3, and TRAIL-receptors. However, FADD likely participates in additional signaling cascades. FADD-null mutations in mice are embryonic-lethal, and analysis of FADD(-)/- T cells from RAG-1(-)/- reconstituted chimeras has suggested a role for FADD in proliferation of mature T cells. Here, we report the generation of T cell-specific FADD-deficient mice via a conditional genomic rescue approach. We find that FADD-deficiency leads to inhibition of T cell development at the CD4(-)CD8(-) stage and a reduction in the number of mature T cells. The FADD mutation does not affect apoptosis or the proximal signaling events of the pre-T cell receptor; introduction of a T cell receptor transgene fails to rescue the mutant phenotype. These data suggest that FADD, through either a death-domain containing receptor or a novel receptor-independent mechanism, is required for the proliferative phase of early T cell development.

Sequence-specific termination by T7 RNA polymerase requires formation of paused conformation prior to the point of RNA release

BACKGROUND

The sequence-specific, hairpin-independent termination signal for the bacteriophage RNA polymerases in Escherichia coli rrnB t1 terminator consists of two modules. The upstream module includes the conserved sequence and the downstream one is U-rich.

RESULTS

Elongation complexes of T7 RNA polymerase paused 2 bp before reaching the termination site at a 500 microM concentration of NTP. At 5-50 microM NTP, however, they paused and terminated there or resumed elongation beyond the termination site. Only at higher concentrations of NTP (500 microM), the pause complex proceeded slowly to and became incompetent at the termination site. At 4 bp or more before the termination site, the unprotected single-stranded region of transcription bubble shrank at the trailing edge to 4-5 bp from approximately 10 bp, resulting from duplex formation of the conserved sequence. The pause and bubble collapse were not observed with an inactive mutant of the termination signal.

CONCLUSION

Sequence-specific termination requires the slow elongation mode of paused conformation, working only at high concentrations of NTP for a few bp prior to the RNA release site. The collapse of bubble that was observed several base pairs before the termination site and/or the resulting duplex might subsequently lead to the paused conformation of T7 elongation complexes.

Expression of cloned cDNA for the human mitochondrial RNA polymerase in Escherichia coli and purification

A full-length cDNA for the mature, mitochondrial form of human mitochondrial RNA polymerase was cloned and expressed under the control of T5 or tac promoter in Escherichia coli. The cDNA was efficiently expressed at 37 degrees C, but virtually all the polymerase produced was insoluble, and renaturation of the inclusion bodies was unsuccessful. When the cells were grown at 25 degrees C, however, a portion of approximately 10% was soluble and active. The protein was purified 100-fold from the soluble lysates to homogeneity by two-step chromatography using Ni-nitrilotriacetic acid-Sepharose and heparin-agarose columns, as an N-terminal histidine tag attached and as the tag cleaved away. The purified polymerases with and without the histidine tag were both active in RNA polymerization in vitro as measured with poly(dA-dT) template, and specific activity was 140,000 units/mg. The purified enzyme has the same biochemical properties as the polymerase fraction partially purified from the human mitochondria, except for the promoter-specific activity that was not observed with the purified polymerase in the presence of mitochondrial transcription factor A. Additional factor(s) and/or mammalian-specific or regulatory modification(s) of the polymerase should be necessary for promoter-specific transcription.

Effects of ipt gene expression on the physiological and chemical characteristics of Artemisia annua L

An isopentenyl transferase gene (ipt) from T-DNA was transferred into Artemisia annua L. via Agrobacterium tumefaciens. The ipt gene was placed in a binary vector under the control of the CaMV 35S promoter. Leaf explants were infected with A. tumefaciens LBA4404 containing pBIipt to induce the buds. Nineteen shoot lines were selected, which were resistant to kanamycin. Polymerase chain reactions and Southern blotting confirmed that at least five shoot lines contained the foreign gene. The results of RT-PCR and Northern blotting analyses suggested that the foreign ipt gene of the transgenic shoot was expressed. Cytokinins, chlorophyll and artemisinin contents were found increased at different degree. Content of cytokinins (iPA and iP) was elevated 2- to 3-fold, chlorophyll increased 20-60% and artemisinin increased 30-70% compared with the control plants, respectively. A direct correlation was found between the contents of cytokinins, chlorophyll and artemisinin. This may be the first report on the relationship between endogenous cytokinin content and the production of secondary metabolites in plants.

Leucine 41 is a gate for water entry in the reduction of Clostridium pasteurianum rubredoxin

Biological electron transfer is an efficient process even though the distances between the redox moieties are often quite large. It is therefore of great interest to gain an understanding of the physical basis of the rates and driving forces of these reactions. The structural relaxation of the protein that occurs upon change in redox state gives rise to the reorganizational energy, which is important in the rates and the driving forces of the proteins involved. To determine the structural relaxation in a redox protein, we have developed methods to hold a redox protein in its final oxidation state during crystallization while maintaining the same pH and salt conditions of the crystallization of the protein in its initial oxidation state. Based on 1.5 A resolution crystal structures and molecular dynamics simulations of oxidized and reduced rubredoxins (Rd) from Clostridium pasteurianum (Cp), the structural rearrangements upon reduction suggest specific mechanisms by which electron transfer reactions of rubredoxin should be facilitated. First, expansion of the [Fe-S] cluster and concomitant contraction of the NH...S hydrogen bonds lead to greater electrostatic stabilization of the extra negative charge. Second, a gating mechanism caused by the conformational change of Leucine 41, a nonpolar side chain, allows transient penetration of water molecules, which greatly increases the polarity of the redox site environment and also provides a source of protons. Our method of producing crystals of Cp Rd from a reducing solution leads to a distribution of water molecules not observed in the crystal structure of the reduced Rd from Pyrococcus furiosus. How general this correlation is among redox proteins must be determined in future work. The combination of our high-resolution crystal structures and molecular dynamics simulations provides a molecular picture of the structural rearrangement that occurs upon reduction in Cp rubredoxin.

Two site contact of elongating transcripts to phage T7 RNA polymerase at C-terminal regions

A series of active elongation complexes of the phage T7 RNA polymerase were obtained through stepwise walking of the polymerase along an immobilized DNA template. Transcripts were radiolabeled at the 16th to 18th residues, and a photocross-linkable 4-thio-UMP was separately incorporated at the 22nd, 24th, 32nd, and 38th residues. Such complexes (up to 51 nucleotides) produced by the incorporation of one nucleotide at a time were isolated and individually subjected to long wave UV cross-linking. Only when the cross-linker was positioned at the 3'-end (-1) of the elongating RNA and 8 nucleotides upstream (-9), was the RNA substantially cross-linked to the polymerase, regardless of how far it was from the 5'-end of the transcripts. Linkage of the 3'-end residue was mapped to the Thr(636)-Met(666) region, which contains nucleotide-binding sites. The -9 residue was cross-linked to the Ala(724)-Met(750) region rather than to the N-terminal region. These two contacts were maintained throughout the elongation complexes and reveal a route of nascent RNA through the T7 RNA polymerase in elongation complexes.

DNA sequencing and genotyping by transcriptional synthesis of chain-terminated RNA ladders and MALDI-TOF mass spectrometry

Sets of RNA ladders can be synthesized by transcription of a bacteriophage-encoded RNA polymerase using 3'-deoxynucleotides as chain terminators. These ladders can be used for sequencing of DNA. Using a nicked form of phage SP6 RNA polymerase in this study substantially enhanced yields of transcriptional sequencing ladders. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of chain-terminated RNA ladders allowed DNA sequence determination of up to 56 nt. It is also demonstrated that A-->G and C-->T variations in heterozygous and homozygous samples can be unambiguously identified by the mass spectrometric analysis. As a step towards single-tube sequencing reactions, alpha-thiotriphosphate nucleotide analogs were used to overcome problems caused by chain terminator-independent, premature termination and by the small mass difference between natural pyrimidine nucleotides.

Insulin-like growth factor-1 protects H9c2 cardiac myoblasts from oxidative stress-induced apoptosis via phosphatidylinositol 3-kinase and extracellular signal-regulated kinase pathways

Oxidative stress plays a critical role in cardiac injuries during ischemia/reperfusion. Insulin-like growth factor-1 (IGF-1) promotes cell survival in a number of cell types, but the effect of IGF-1 on the oxidative stress has not been elucidated in cardiac muscle cells. Therefore, we examined the role of IGF-1 signaling pathway in cell survival against H2O2-induced apoptosis in H9c2 cardiac myoblasts. H2O2 treatment induced apoptosis in H9c2 cells, and pretreatment of cells with IGF-1 suppressed apoptotic cell death. The antiapoptotic effect of IGF-1 was blocked by LY294002 (an inhibitor of phosphatidylinositol 3-kinase) and by PD98059 (an inhibitor of extracellular signal-regulated kinase (ERK)). The protective effect of IGF-1 was also blocked by rapamycin (an inhibitor of p70 S6 kinase). Furthermore, H9c2 cells stably transfected with constitutively active PI 3-kinase (H9c2-p110*) and Akt (H9c2-Gag-Akt) constructs were more resistant to H2O2 cytotoxicity than control cells. Although H2O2 activates both p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase (JNK), IGF-1 inhibited only JNK activation. Activated PI 3-kinase (H9c2-p110*) and pretreatment of cells with IGF-1 down-regulated Bax protein levels compared to control cells. Taken together, our results suggest that IGF-1 transmits a survival signal against oxidative stress-induced apoptosis in H9c2 cells via PI 3-kinase and ERK-dependent pathways and the protective effect of IGF-1 is associated with the inhibition of JNK activation and Bax expression.

Development and differentiation of the anuran auditory brainstem during metamorphosis: an acetylcholinesterase histochemical study

The time course of cell differentiation and the presence of histochemically defined areas in brainstem auditory nuclei were examined in developing bullfrogs, Rana catesbeiana, using cresyl violet staining and acetylcholinesterase (AChE) histochemistry. In the medulla, the dorsolateral nucleus (DLN) can be seen as a distinct structure in its adult location only at Gosner stage 40 and beyond. The majority of cells in the DLN are not fully differentiated until late metamorphic climax (stages 45-46) and early postmetamorphosis. The more ventral vestibular nucleus differentiates earlier (stage 37) than the DLN. Adult-like organization of auditory nuclei in the torus semicircularis (TS) of the midbrain cannot be reliably discerned until metamorphic climax stages. Cellular masses in the brainstem reveal AChE from the earliest stage examined (stage 27) but the intensity of staining differs among cell groups. Staining intensity in the DLN is at a peak in recently metamorphosed froglets. The time course of cell differentiation in the DLN precedes slightly or is coincident with the increased, transient presence of AChE. Staining of the superior olive stabilizes at a moderate level in early postmetamorphic stages. Ventral regions of the principal nucleus in the TS stain more intensely than dorsal regions beginning at stage 40. This dorsal-ventral gradient in staining persists in adult stages. There is a transient decline in staining of the laminar nucleus in metamorphic climax stages. Staining intensity in the magnocellular nucleus peaks during stages 40-46 and in early postmetamorphic froglets and then declines in adults, paralleling the pattern seen in the DLN. These data suggest that metamorphic climax and early froglet periods are an important developmental window for major differentiation and maturational events in the auditory brainstem.

Introduction of HIV type 1 subtype E virus into South Korea

Subtype E HIV-1 is the most prevalent strain in Southeast Asia. Although subtype B is prevalent in Korea, geographical distance and increases in travel may lead to the spread of subtype E in Korea. Therefore, we tried to identify and monitor the patterns of HIV subtype E virus introduction into Korea. The divergence of nucleotide sequences within the envelope region (V3 to V5) of Korean subtype E isolates ranged from 4.3 to 14.6% (n = 8; mean, 9.5 +/- 2.8%). In pairwise comparisons of subtype E isolates between Korea and other regions, the divergence of nucleotide sequences between 8 Korean and 16 Asian subtype E variants ranged from 1.3 to 15.2% (mean, 7.8 +/- 2.6%), whereas the divergence of nucleotide sequences between 8 Korean and 2 African variants ranged from 11.7 to 20.7% (mean, 15.4 +/- 2.2%). A phylogenetic tree showed that Korean subtype E isolates cluster with the Asian isolates but far from the African isolates. These epidemiological and molecular epidemiological data suggest that HIV-1 subtype E strains have been transmitted into Korea from endemic areas of Southeast Asia rather from Africa.

Translational suppression by hammerhead ribozymes and inactive variants in S. cerevisiae

The activity of hammerhead ribozymes in S. cerevisiae was assessed using two ribozymes that were designed to intramolecularly attack the hepatitis B viral X mRNA. The ribozymes effectively suppressed the expression of the X-lacZ fusion gene, when they were inserted at the 5' end of the X mRNA. The ribozymes cleaved the target RNA efficiently at the targeted phosphodiester bond, but the inactive mutants carrying G5-to-A substitution in the core did not, as the total RNA preparations of yeast extracts was assayed by primer extension. These G5A mutants, however, exerted the suppression as effectively as the wild-type ribozymes. The results, with several mutations introduced to a ribozyme, suggested that either mere formation of hammerhead-like structures with the three stems, or the formation of any two stems, could inhibit translation. Thus, the hammerhead-like structures, leading to cleavage or not, could effectively suppress translation, especially when formed around the initiation codon. The G5-to-A and U7-to-G mutations and replacement of the stem-II hairpin tetraloop did not appear to affect the formation of the inhibitory structure(s). The inhibition that was observed when stems I and III were directly connected without a loop or with a stem II hairpin was completely relieved when they were connected with only the loop of stem II (not containing the stem portion).

Bacteriophage SP6 RNA polymerase mutants with altered termination efficiency and elongation processivity

An Escherichia coli strain containing two plasmids was developed for in vivo isolation of the phage SP6 RNA polymerase mutants. It was developed to isolate mutants with increased proficiency of termination at the SP6 terminator and/or with reduced elongation processivity. Mutations were randomly introduced into an N-terminal third of the polymerase gene that was placed under a lac promoter in one plasmid. In the other plasmid, a promoter-lacking lacZ gene modified for reduced translation efficiency was placed downstream of a tandem pair of the SP6 terminator located downstream of an SP6 promoter-chloramphenicol acetyltransferase gene. Termination-up mutants were selected in vivo as they rendered LacZ activity level lower than the wild-type, without reducing chloramphenicol resistance substantially. Three such mutants (M15L, M15S, and D117G) were purified, and their termination efficiencies were measured in vitro at two different intrinsic termination signals in the E. coli rrnB terminator t1 that are different in requiring RNA hairpin formation. All three mutations enhanced termination efficiencies in vitro at the SP6 terminator and the upstream signal of rrnB t1, but reduced the efficiency at the downstream signal of it. All the mutations reduced elongation processivity, as the mutants produced much less amounts of large transcripts (2.1 kb) than the wild-type but the similar amounts of small transcripts (up to 670 nt). Thus, the mutations, all reducing elongation processivity of the polymerase, exhibited opposite effects on the two types of intrinsic termination signals, suggesting that the two mechanisms involve different interactions with the phage RNA polymerase.

[Studies on separation and identification of Rhizoma coptidis brugs based on microemulsion thin-layer chromatography]

OBJECTIVE

To investigate the use of microemulsion TLC for the separation and identification of Rhizoma Coptidis drugs.

METHOD

Thirteen Rhizoma Coptidis drugs were separated and identified with six kinds of SDS/n-C4H9OH/n-C7H16/H2O microemulsions as mobile phase on polyamide film. Effects of microemulsions on separation were investigated.

RESULTS

The best mobile phase was the O/W microemulsion(containing 75% water). Compared with general mobile phases, the separation and detection could be improved and the test conditions were more tolerant.

CONCLUSION

This new method is simple, accurate and efficient for the separation and identification of Rhizoma Coptidis drugs.

Effects of saturation mutagenesis of the phage SP6 promoter on transcription activity, presented by activity logos

A full set of SP6 promoter variants with all possible single substitutions at positions -17 to +5 was constructed. Transcription activities of these variants were individually measured in vivo and in vitro to determine the contribution of each base pair to the promoter activity. The in vivo activity was measured indirectly by transcriptional interference of the replication of promoter-bearing plasmids. This activity depends most highly on residues -11, -9, -8, -7, and +1 (initiation site). All substitutions at -11, -9, -8, and -7 abolished formation of closed complexes, except for A-8C. These residues are involved in base-specific interactions with the polymerase, and the substitutions exhibit the same strong inhibition in vitro. In contrast, the in vitro activities of some other variants, measured on linearized templates, were different from those in vivo. Some variants at -13, -4, and -2, among others, showed exceptionally higher activities in vivo than in vitro, supporting the possibility that these residues are involved in postbinding steps, including template melting and bending. The A-3T variant showed much lower activity in vivo than in vitro, but it bound to the polymerase 2-fold more than the consensus sequence and is possibly involved in polymerase binding. A quantitative hierarchy of all the base pairs is graphically displayed by activity logos, revealing the energetic contribution of each base pair to the activity.

[Effects of xiaopi yishen oral liquid on hypothalamus-pituitary-adrenal gland-thymus axis in stressed rats]

OBJECTIVE

To investigate the effect of Xiaopi Yishen (XPYS) oral liquid on the rats under repeated forced cold water swimming (RFCWS) stress.

METHODS

The changes of serum monoamine, ascorbic acid levels in adrenal gland, monoamine levels in hypothalamus and hypophysis, and thymus index were determined.

RESULTS

XPYS lowered the increasing of serum DA, 5-HT, improved the reducing of ascorbic acid in adrenal gland and NE, HVA, 5-HT, 5-HITT in hypothalamus and hypophysis of RFCWS-stressed rats.

CONCLUSION

The mechanism of XPYS is in connection with the regulation of hypothalamus-pituitary-adrenal gland-thymus axis.

Modulation of the redox potential of the [Fe(SCys)(4)] site in rubredoxin by the orientation of a peptide dipole

Rubredoxins (Rds) may be separated into two classes based upon the correlation of their reduction potentials with the identity of residue 44; those with Ala44 have reduction potentials that are approximately 50 mV higher than those with Val44. The smaller side chain volume occupied by Ala44 relative to that occupied by Val44 has been proposed to explain the increase in the reduction potential, based upon changes in the Gly43-Ala44 peptide bond orientation and the distance to the [Fe(SCys)(4)] center in the Pyrococcus furiosus (Pf) Rd crystal structure compared to those of Gly43-Val44 in the Clostridium pasteurianum (Cp) Rd crystal structure. As an experimental test of this hypothesis, single-site Val44 <--> Ala44 exchange mutants, [V44A]Cp and [A44V]Pf Rds, have been cloned and expressed. Reduction potentials of these residue 44 variants and pertinent features of the X-ray crystal structure of [V44A]Cp Rd are reported. Relative to those of wild-type Cp and Pf Rds, the V44A mutation in Cp Rd results in an 86 mV increase in midpoint reduction potential and the [A44V] mutation in Pf Rd results in a 95 mV decrease in midpoint reduction potential, respectively. In the crystal structure of [V44A]Cp Rd, the peptide bond between residues 43 and 44 is approximately 0.3 A closer to the Fe center and the hydrogen bond distance between the residue 44 peptide nitrogen and the Cys42 gamma-sulfur decreases by 0.32 A compared to the analogous distances in the wild-type Cp Rd crystal structure. The results described herein support the prediction that the identity of residue 44 alone determines whether a Rd reduction potential of about -50 or 0 mV is observed.