Insertion preference of maize and rice miniature inverted repeat transposable elements as revealed by the analysis of nested elements

A 128-bp insertion into the maize waxy-B2 allele led to the discovery of Tourist, a family of miniature inverted repeat transposable elements (MITEs). As a special category of nonautonomous elements, MITEs are distinguished by their high copy number, small size, and close association with plant genes. In maize, some Tourist elements (named Tourist-Zm) are present as adjacent or nested insertions. To determine whether the formation of multimers is a common feature of MITEs, we performed a more thorough survey, including an estimation of the proportion of multimers, with 30.2 Mb of publicly available rice genome sequence. Among the 6600 MITEs identified, >10% were present as multimers. The proportion of multimers differs for different MITE families. For some MITE families, a high frequency of self-insertions was found. The fact that all 340 multimers are unique indicates that the multimers are not capable of further amplification.

Insertion preference of maize and rice miniature inverted repeat transposable elements as revealed by the analysis of nested elements

A 128-bp insertion into the maize waxy-B2 allele led to the discovery of Tourist, a family of miniature inverted repeat transposable elements (MITEs). As a special category of nonautonomous elements, MITEs are distinguished by their high copy number, small size, and close association with plant genes. In maize, some Tourist elements (named Tourist-Zm) are present as adjacent or nested insertions. To determine whether the formation of multimers is a common feature of MITEs, we performed a more thorough survey, including an estimation of the proportion of multimers, with 30.2 Mb of publicly available rice genome sequence. Among the 6600 MITEs identified, >10% were present as multimers. The proportion of multimers differs for different MITE families. For some MITE families, a high frequency of self-insertions was found. The fact that all 340 multimers are unique indicates that the multimers are not capable of further amplification.

P instability factor: an active maize transposon system associated with the amplification of Tourist-like MITEs and a new superfamily of transposases

Miniature inverted-repeat transposable elements (MITEs) are widespread and abundant in both plant and animal genomes. Despite the discovery and characterization of many MITE families, their origin and transposition mechanism are still poorly understood, largely because MITEs are nonautonomous elements with no coding capacity. The starting point for this study was P instability factor (PIF), an active DNA transposable element family from maize that was first identified following multiple mutagenic insertions into exactly the same site in intron 2 of the maize anthocyanin regulatory gene R. In this study we report the isolation of a maize Tourist-like MITE family called miniature PIF (mPIF) that shares several features with PIF elements, including identical terminal inverted repeats, similar subterminal sequences, and an unusual but striking preference for an extended 9-bp target site. These shared features indicate that mPIF and PIF elements were amplified by the same or a closely related transposase. This transposase was identified through the isolation of several PIF elements and the identification of one element (called PIFa) that cosegregated with PIF activity. PIFa encodes a putative protein with homologs in Arabidopsis, rice, sorghum, nematodes, and a fungus. Our data suggest that PIFa and these PIF-like elements belong to a new eukaryotic DNA transposon superfamily that is distantly related to the bacterial IS5 group and are responsible for the origin and spread of Tourist-like MITEs.

1,2-aryl and 1,2-hydride migration in transition metal complex catalyzed diazo decomposition: a novel approach to alpha-aryl-beta-enamino esters

N-Tosyl diazoketamines were prepared by addition of the ethyl alpha-diazoacetate anion to N-sulfonylimines. The diazo decomposition of the diazoketamines with Rh(2)(OAc)(4) complex resulted in aryl migration to give alpha-aryl-beta-enamino esters in good yields and high stereoselectivity. The effect of the catalysts on the migratory aptitude of 1,2-aryl over 1,2-hydride migration was studied. A reaction mechanism involving a "bridged" phenonium ion is proposed. Reaction: see text.

Mouse CLK-1 is imported into mitochondria by an unusual process that requires a leader sequence but no membrane potential

clk-1 has been identified and characterized in the nematode Caenorhabditis elegans as a gene that affects the rates, regularity, and synchrony of physiological processes. The CLK-1 protein is mitochondrial and is required for ubiquinone biosynthesis in yeast and in worms, but its biochemical function remains unclear. We have studied the expression of murine mclk1 in a variety of tissues, and we find that the pattern of mclk1 mRNA accumulation closely resembles that of mitochondrial genes involved in oxidative phosphorylation. The pattern of protein accumulation, however, is sharply distinct in some tissues; mCLK1 appears relatively enriched in the gut and depleted in the nervous tissue. We also show that mCLK1 is synthesized as a preprotein that is imported into the mitochondrial matrix, where a leader sequence is cleaved off and the protein becomes loosely associated with the inner membrane. However, in contrast to all known mitochondrial proteins that contain a cleavable pre-sequence, the import of mCLK1 does not require a mitochondrial membrane potential.

[Cloning and expression of VHB gene in D-arabitol producing yeast]

Recombinant plasmid pVgb-EX2 containing Vitreoscilla hemoglobin gene vgb and formaldehyde resistant gene SFA1 was constructed and transformed into D-arabitol producing yeast strain Saccharomyces sp. X-62. The fact that the amount of VHb in transformant cells was considerably higher than that in control cells indicated that gene vgb was expressed in transformant cells. D-arabitol productivity and yield of fermentation by transformants were improved. The most improvement of D-arabitol productivity in repeat experiments reached 27.3%. It appeared that the fermentation productivity of D-arabitol was relative to the amount of VHb in cells under experimental conditions.

Optimal combinations of systematic sextant and laterally directed biopsies for the detection of prostate cancer

PURPOSE

The standard sextant protocol for obtaining transrectal ultrasound guided biopsy of the prostate has been shown to underestimate the presence of prostate cancer. Studies have demonstrated an increased cancer detection rate with additional laterally directed biopsies. We compared the sensitivity of individual biopsy cores and evaluated combinations of these cores to identify an optimal biopsy strategy.

MATERIALS AND METHODS

A total of 396 consecutive patients underwent biopsy of the lateral peripheral zone in addition to standard sextant biopsy. The cancer detection rate for each biopsy core was calculated. The sensitivity of different combinations of biopsy cores was compared with those of standard sextant biopsies and with a 12 core biopsy protocol that combined the standard sextant biopsy with a complete set of laterally directed cores.

RESULTS

Cancer was detected in 160 of 396 (40.3%) patients. Of the possible combinations of biopsy cores a strategy that included laterally directed cores at the base, mid gland and apex of the prostate with mid lobar base and apical cores detected 98.5% of cancers. The detection rate of this 10 core biopsy regimen was significantly better than that of the standard sextant protocol (p < or =0.001), and was equivalent to that of the 12 core regional biopsy (p > or =0.302).

CONCLUSIONS

The standard sextant protocol failed to detect a large proportion of cancers located laterally in the peripheral zone. A 10 core biopsy regimen that combined laterally directed cores at the base, mid gland and apex of the prostate with mid lobar biopsy cores at the base and apex maximizes the sensitivity of transrectal ultrasound guided systematic biopsy.

PHM is required for normal developmental transitions and for biosynthesis of secretory peptides in Drosophila

To understand the roles of secretory peptides in developmental signaling, we have studied Drosophila mutant for the gene peptidylglycine alpha-hydroxylating monooxygenase (PHM). PHM is the rate-limiting enzyme for C-terminal alpha-amidation, a specific and necessary modification of secretory peptides. In insects, more than 90% of known or predicted neuropeptides are amidated. PHM mutants lack PHM protein and enzyme activity; most null animals die as late embryos with few morphological defects. Natural and synthetic PHM hypomorphs revealed phenotypes that resembled those of animals with mutations in genes of the ecdysone-inducible regulatory circuit. Animals bearing a strong hypomorphic allele contain no detectable PHM enzymatic activity or protein; approximately 50% hatch and initially display normal behavior, then die as young larvae, often while attempting to molt. PHM mutants were rescued with daily induction of a PHM transgene and complete rescue was seen with induction limited to the first 4 days after egg-laying. The rescued mutant adults produced progeny which survived to various stages up through metamorphosis (synthetic hypomorphs) and displayed prepupal and pupal phenotypes resembling those of ecdysone-response gene mutations. Examination of neuropeptide biosynthesis in PHM mutants revealed specific disruptions: Amidated peptides were largely absent in strong hypomorphs, but peptide precursors, a nonamidated neuropeptide, nonpeptide transmitters, and other peptide biosynthetic enzymes were readily detected. Mutant adults that were produced by a minimal rescue schedule had lowered PHM enzyme levels and reproducibly altered patterns of amidated neuropeptides in the CNS. These deficits were partially reversed within 24 h by a single PHM induction in the adult stage. These genetic results support the hypothesis that secretory peptide signaling is critical for transitions between developmental stages, without strongly affecting morphogenetic events within a stage. Further, they show that PHM is required for peptide alpha-amidating activity throughout the life of Drosophila. Finally, they define novel methods to study neural and endocrine peptide biosynthesis and functions in vivo.

Impaired affinity maturation in Cr2-/- mice is rescued by adjuvants without improvement in germinal center development

Cr2-/- mice have an impairment in humoral immunity, as shown by the decrease in the Ab titers against T cell-dependent Ags and abnormalities in germinal center formation. Germinal centers are present, but they are decreased in size and number, indicating problems in their development. In this study, we investigated whether this abnormality in germinal center development is associated with problems in the establishment of optimal affinity maturation and the generation of memory B cells, processes closely related to the germinal center reaction. We immunized the Cr2-/- animals with different Ags with or without adjuvants. We showed that, when immunized without adjuvants, complement receptors are absolutely required for optimal affinity maturation. Although limited affinity maturation is elicited in the Cr2-/- Ab response, it is decreased as compared with normal animals. Memory B cell generation is also impaired. In the presence of adjuvants, germinal center development in the Cr2-/- mice is still abnormal, as demonstrated by their decreased size and number. Surprisingly, adjuvants establish optimal affinity maturation and partially restore the amount of Ab produced during the primary response and memory B cell generation. However, adjuvants cannot improve the ability of follicular dendritic cells to retain Ags in the form of immune complexes. These observations indicate that immunization with inflammatory Ags offset some of the immunological abnormalities found in the Cr2-/- mice and show that optimal affinity maturation in the Cr2-/- mice can be achieved in the absence of normal germinal centers.

c-myc gene inactivation during induction of nasopharyngeal carcinoma cells with retinoic acid

OBJECTIVE

To investigate the effects of retinoic acid (RA) on the growth, morphology, oncogene expression and regulation of nasopharyngeal carcinoma cells.

METHODS

Nasopharyngeal carcinoma cell line (HNE1) was induced by RA. The RA-treated and control cells were established and cellular morphology and growth patterns were defined. Oncogene expression and regulation were detected by Northern hybridization and DNase-I hypersensitive site analysis.

RESULTS

RA markedly inhibited cell growth. The growth of HNE1 cells was reduced to 50% of the control level on the 4th day of RA (10(-4) mol/L) treatment. After 4 days of treatment, the rapidly growing polygonal cells were reversed into a slow growing phenotype, with flattened morphology similar to fibroblast-like cells. Northern hybridization showed that c-myc and c-Ha-ras expression was high in HNE1 cells and undetectable in normal blood cells. c-myc was down-regulated at 48 h of RA treatment. In contrast, the c-Ha-ras was not affected. DNase I hypersensitive site analysis detected changes in the regulatory elements of c-myc and c-Ha-ras genes. 5 hypersensitive sites were found in the c-myc of HNE1 cells, while 3 hypersensitive sites disappeared upon HNE1 induction. However, only 1 hypersensitive site was found in c-Ha-ras of RA treated cells and controls. In normal peripheral white blood cells, no DNase I hypersensitive sites were found in the inactive c-myc and c-Ha-ras gene.

CONCLUSION

RA can induce differentiation in a nasopharyngeal carcinoma cell line at high concentration of RA; HNE1 shows some similar patterns of DNase I hypersensitive sites with the common one in other types of cells expressing c-myc. The repression of c-myc expression with induction is accompanied by the loss of 3 DNase-I hypersensitive sites; c-myc has more than one inactive conformation.

Antibody production in mice deficient for complement receptors 1 and 2 can be induced by IgG/Ag and IgE/Ag, but not IgM/Ag complexes

Deficiencies in C factors C2, C3, or C4 as well as lack of C receptors 1 and 2 (CR1/2) lead to impaired Ab production. Classical pathway activation plays a major role, as mice deficient in factor B, a key factor in the alternative pathway, have normal Ab production. Abs in complex with their specific Ag are known to feedback regulate the Ab response, and enhanced responses are initiated by IgM, IgE, and IgG. IgM acts via the C system, whereas IgE and IgG can operate independently of C via Fc receptors. Here we have investigated whether these isotypes are able to enhance Ab responses in mice lacking CR1/2. SRBC-specific IgM, administered with SRBC, does not enhance Ab responses in these animals. In contrast, 2,4, 6-trinitrophenyl-specific IgE and IgG2a, administered with BSA-2,4, 6-trinitrophenyl, induce potent Ab responses in CR1/2-deficient mice. Additionally, BSA administered with CFA or alum induced strong Ab responses in the absence of CR1/2. These results indicate that CR1/2 is needed to promote IgM-mediated induction of primary Ab responses. The data also show that the need for CR1/2 can be circumvented by Abs typical of a secondary immune response forming complexes with Ag or by conventional adjuvants, presumably mimicking physiological inflammatory reactions.

[Molecular cloning of a novel gene located on chromosome 3p25.3 and an analysis of its expression in nasopharyngeal carcinoma]

OBJECTIVE

To obtain the novel genes associated with human nasopharyngeal carcinoma(NPC) on chromosome 3p24-26.

METHODS

Twenty epithelial-derived expressed sequence tags(EST) were selected from chromosome 3p24-26 where loss of heterozygosity(LOH) frequently occurs in NPC tissues. Primers were designed based on the sequences of these ESTs. RT-PCR was used to amply their corresponding cDNA fragments from NPC cell line HNE1 and primary cultures of normal nasopharyngeal epithelial cells. The differential expression of two ESTs, T93093 and R41598, was confirmed by Northern blot. Then, expression of EST T93093 was further detected in 7 normal nasopharyngeal and 19 NPC biopsies. cDNA library screening was used to get its full cDNA sequence and the sequence of this novel gene was analyzed by bioinformatics.

RESULTS

Thirteen ESTs(T62511, N39155, N68660, R61275, T95314, R06143, H52697, H66521, AA128685, AA284537, N52379, AA054180, and H98090) showed the similar expression level and 5 ESTs(R00732, R07573, R98052, H91759, H17566) showed no expression in both types of cells. EST T93093 was down-expressed, whereas EST R41598 up-expressed in NPC HNE1 cells. The EST T93093 was also found to be down-expressed in 26.3%(5/19) of NPC biopsies. The full length cDNA of this gene was obtained and named NAG-7, which is located at chromosome 3p25.3. Its 1677 bp full length cDNA has a potential open reading frame(ORF) predicting a 94 amino acid protein with a molecular weight of 11023.87 Dalton. Bioinformatics analysis of the NAG-7 gene shows that it is a transmembrane protein containing a protein kinase C(PKC) phosphorylation site and a myristyl site. It has no significant homology to any reported genes in database of GenBank(AF086709).

CONCLUSION

NAG-7 is a novel gene down-expressed in NPC, which may be involved in the development of NPC.

A cDNA located on chromosome 7q32 shows loss of expression in epithelial cell line of nasopharyngeal carcinoma

OBJECTIVE

To isolate and clone the tumor suppressor gene on chromosomal region 7q32 correlated with the carcinogenesis of human nasopharyngeal carcinoma (NPC).

METHODS

The genotypes of polymorphic microsatellite markers on 7q32 in DNA from 24 biopsies of nasopharyngeal carcinoma and matched normal blood cells were identified. The expression levels of 20 expressed sequence tags (ESTs) on 7q32 between human nasopharyngeal carcinoma epithelial 1 (HNE1) and primary cultures of normal nasopharyngeal epithelial (PNNE) cells were compared using differential RT-PCR and Northern hybridization. The quantity of AA070437 DNA and mRNA was detected by differential PCR and differential RT-PCR, respectively.

RESULTS

Loss of heterozygosity (LOH) was found in 25%-46% of NPC biopsies. AA070437 EST expression was down-regulated in HNE1 cell compared to PNNE cells. The down-regulation of AA070437 was found in 30.7% of NPC biopsies and allelic loss of AA070437 was observed in 29.1% of NPC biopsies.

CONCLUSION

Our results show that AA070437 EST is negatively related with the occurrence of human NPC and may represent a candidate tumor suppressor gene of NPC on 7q32.

Peptide and peptide mimetic inhibitors of antigen presentation by HLA-DR class II MHC molecules. Design, structure-activity relationships, and X-ray crystal structures

Molecular features of ligand binding to MHC class II HLA-DR molecules have been elucidated through a combination of peptide structure-activity studies and structure-based drug design, resulting in analogues with nanomolar affinity in binding assays. Stabilization of lead compounds against cathepsin B cleavage by N-methylation of noncritical backbone NH groups or by dipeptide mimetic substitutions has generated analogues that compete effectively against protein antigens in cellular assays, resulting in inhibition of T-cell proliferation. Crystal structures of four ternary complexes of different peptide mimetics with the rheumatoid arthritis-linked MHC DRB10401 and the bacterial superantigen SEB have been obtained. Peptide-sugar hybrids have also been identified using a structure-based design approach in which the sugar residue replaces a dipeptide. These studies illustrate the complementary roles played by phage display library methods, peptide analogue SAR, peptide mimetics substitutions, and structure-based drug design in the discovery of inhibitors of antigen presentation by MHC class II HLA-DR molecules.

Detailed allelic loss mapping on 7q32 in nasopharyngeal carcinoma

OBJECTIVE

The present research group had found high frequency of loss of heterozygosity(LOH) of D7S500-D7S495 on chromosome band 7q32 in nasopharyngeal carcinoma, this study was conducted to further find the deletion region.

METHODS

Higher density of loci on 7q32 in 30 tumors was studied by using microsatellite analysis.

RESULTS

The frequency of LOH was 63.3%. The highest frequency of LOH was identified at the loci of D7S500-D7S509-D7S495, among which a common deletion of D7S509 was found.

CONCLUSION

A putative tumor suppressor gene may be present around D7S509.

Studies on production of pullulan by the feed batch fermentation

The feed-batch fermentation of pullulan was investigated based on the conditions of batch fermentation. The optimal conditions of pullulan fermentation were determined by the investigation on the effect of feed mode, initial feed time, intermittent time, and composition of the feed solution on parameters such as productivity, conversion yield, biomass, dissolved oxygen (DO), pH of the fermentation broth, viscosity of the fermentation broth and molecular weight of the product. Above 70% of conversion yield and 100 kD of average molecular weight of the product was obtained at the optimal conditions.

Residual oil fly ash induces cytotoxicity and mucin secretion by guinea pig tracheal epithelial cells via an oxidant-mediated mechanism

Inhalation of ambient air particulate matter (PM) is associated with pulmonary injury and inflammation. Using primary cultures of guinea pig tracheal epithelial (GPTE) cells as an in vitro model of airway epithelium, we examined effects of exposure to suspensions of six different emission and ambient air PM samples: residual oil fly ash (ROFA) from an electrical power plant; fly ash from a domestic oil burning furnace (DOFA); ambient air dust from St. Louis (STL), Ottawa (OT), and Washington, DC (WDC); and volcanic ash from the eruption of Mount Saint Helens (MSH) in 1980. Effects of these particulates on cell viability (assessed via LDH assay), secretion of mucin (measured by a monoclonal antibody-based ELISA), and steady-state mRNA levels of the mucin gene MUC2 were determined. ROFA was the most toxic of the dusts tested, as it significantly increased LDH release following a 24-h incubation with 50 microg/cm(2) ROFA. ROFA also enhanced MUC2 mRNA after 4-h exposure, and mucin secretion after 8 h. ROFA-induced mucin secretion and cytotoxicity were attenuated by the oxidant scavenger, dimethylthiourea (DMTU). ROFA exposure also depleted cells of glutathione (GSH). Relatedly, depletion of intracellular GSH by treatment of the cells with buthionine sulfoxamine (BSO) also provoked mucin secretion, as well as enhancing the secretory effect of ROFA when the two agents were added together. L-NMA, the nitric oxide synthase (NOS) inhibitor, did not affect ROFA-induced mucin secretion. Of the soluble transition metals in ROFA (nickel, iron, vanadium), only vanadium individually, or combinations of the metals containing vanadium, provoked secretion. The results suggest ROFA enhances mucin secretion and generates toxicity in vitro to airway epithelium via a mechanism(s) involving generation of oxidant stress, perhaps related to depletion of cellular antioxidant capacity. Deleterious effects of inhalation of ROFA in the respiratory tract in vivo may relate to these cellular responses. Vanadium, a component of ROFA, may be important in generating these reactions.

Genomic organization of the serine protease light chain of mouse complement factor I gene

A portion of the mouse complement factor I (mCFI) gene encoding for the mCFI light chain was cloned from a mouse 129/SVJ1 bacterial artificial chromosome library. It contains five exons and four introns. The intron sizes are remarkably different from the human homolog. Several polymorphisms were found in exon 13. One polymorphism was in the coding region, which causes a threonine in the Balb/c mCFI to be replaced by an isoleucine in the 129/SVJ1 mCFI. The other two polymorphisms are located in the 3' untranslated region. The organization of the serine protease domain in mCFI is similar to that of trypsin but very different from that of the other complement serine proteases.

[A nasopharyngeal carcinoma negatively related EST on 7q32]

To isolate and clone the tumor suppressor gene on chromosomal region 7q32 that corelated with the occurrence of human NPC, we detected the genotype of polymorphic microsatellite markers on 7q32 in 24 nasopharyngeal carcinoma biopsies and matched normal lymphocyte DNA. LOH was found in 30% biopsies. Using differential RT-PCR and Northern hybridization we compared the expression level of 20 EST on 7q32 between NPC cell line HNE1 and primary culture of normal nasopharyngeal epithelial cell, and found AA070437 EST expressed high in primary culture of normal nasopharyngeal epithelial cell, but very low in HNE1. Differential RT-PCR (dRT-PCR) analysis showed that the expression level of AA070437 was lower in 30.7% NPC biopses than in normal cell. Differential PCR (dPCR) showed that allelic loss of AA070437 was observed in 29.1% NPC biopses. This EST is a part of sequence of a new gene compared with GeneBank database. Our results showed that AA070437 EST negatively related with the occurrence of human NPC is a candidate of tumor suppressor gene of NPC on 7q32.

Ectopic expression of the nude gene induces hyperproliferation and defects in differentiation: implications for the self-renewal of cutaneous epithelia

Nude mice are characterized by the absence of visible hair, epidermal defects, and the failure to develop a thymus. This phenotype results from loss-of-function mutations in Whn (Hfh11), a winged-helix transcription factor. In murine epidermis and hair follicles, endogenous whn expression is induced as epithelial cells initiate terminal differentiation. Using the promoter for the differentiation marker involucrin, transgenic mice that ectopically express whn in stratified squamous epithelia, hair follicles, and the transitional epithelium of the urinary tract were generated. Transgenic epidermis and hair follicles displayed impaired terminal differentiation and a subset of hair defects, such as delayed growth, a waved coat, and curly whiskers, correlated with decreased transforming growth factor (TGF)-alpha expression. The exogenous Whn protein also stimulated epithelial cell multiplication. In the epidermis, basal keratinocytes exhibited hyperproliferation, though transgene expression was restricted to suprabasal, postmitotic cells. Hair follicles failed to enter telogen (a resting period) and remained continuously in an abnormal anagen (the growth phase of the hair cycle). Ureter epithelium developed severe hyperplasia, leading to the obstruction of urine outflow and death from hydronephrosis. Though an immune infiltrate was present occasionally in transgenic skin, the infiltrate was not the primary cause of the epithelial hyperproliferation, as the immune reaction was not observed in all affected transgenics, and the transgene induced identical skin and urinary tract abnormalities in immunodeficient Rag1-null mice. Given the effects of the transgene on cell proliferation and TGFalpha expression, the results suggest that Whn modulates growth factor production by differentiating epithelial cells, thereby regulating the balance between proliferative and postmitotic populations in self-renewing epithelia.

Hyperhomocysteinemia and hyperlipidemia in coronary heart disease

OBJECTIVE

To examine the relationship between coronary heart disease (CHD) and serum lipid, plasma homocysteine (HCY) as well as the factors related to HCY metabolisms.

METHODS

The mutation of the 677C-->T transition of 5, 10-methylenetetrahydrofolate reductase (MTHFR) was determined by PCR-based assay. Whole-blood and plasma folate and plasma vitamin B12, as cofactors of MTHFR, were determined by radio-immunologic assay. Plasma HCY was determined by HPLC.

RESULTS

Patients with CHD had elevated plasma HCY concentrations (17.38 +/- 1.94 mumol/L vs 10.25 +/- 1.57 mumol/L, P < 0.01). In patients with myocardial infarction (MI) and family history (FH) of CHD, plasma HCY were elevated even higher (P < 0.05). Plasma HCY concentrations had significant non-linear inverse correlation with plasma folate and B12 concentrations, i.e. the lower the serum folate or B12 concentrations, the higher the plasma HCY concentrations (P < 0.01). Patients with homozygous mutants had higher plasma HCY concentrations. Patients with CHD had increased serum Chol and LDL-C and Apo-B levels (P < 0.01, P < 0.05 and P < 0.05 respectively). But plasma HCY concentrations had no correlation with serum lipid levels. 24.1% of the patients had high lipid and high HCY level, 25.9% had high lipid level and normal HCY level, 20.4% had normal lipid and high HCY level, and 29.6% had normal lipid and HCY level.

CONCLUSIONS

HCY may have strong association with the genesis of CHD. Low plasma folate and B12 concentrations may induce Hyperhomocysteinemia [HH(e)]. Plasma HCY concentrations have no correlation with serum lipid levels, so HCY may be an independent risk factor. CHD may be induced by different mechanisms and can be classified into hyperlipidemia, HH (e) and normolipidemia, and normohomocysteinemia.

Selective activation of the versican promoter by epithelial- mesenchymal interactions during hair follicle development

Interaction between the epithelium and the mesenchyme is an essential feature of organogenesis, including hair follicle formation. The dermal papilla (DP), a dense aggregate of specialized dermis-derived stromal cells located at the bottom of the follicle, is a major component of hair that signals the follicular epithelial cells to prolong the hair growth process. However, little is known about DP-specific gene activation with regard to hair induction. In this study we demonstrate that a short fragment (839 bp) of the human versican (a core protein of one of the matrix chondroitin sulfate proteoglycans) promoter is sufficient to activate lacZ reporter gene expression in the DP of postnatal transgenic mice and also in the condensed mesenchyme (the origin of the DP) beneath the hair placode during hair follicle embryogenesis. Using the same versican promoter with green fluorescent protein (GFP), large numbers of fresh pelage DP cells were isolated from newborn transgenic skin by high-speed cell sorting. These GFP-positive DP cells showed abundant versican mRNA, confirming that the reporter molecules reflected endogenous versican gene expression. These sorted GFP-positive cells showed DP-like morphology in culture, but both GFP and versican expression was lost during primary culture. In vivo hair growth assays showed that GFP-positive cells could induce hair when grafted with epithelial cells, whereas GFP-negative cells grafted with epithelium or GFP-positive cells alone did not. These results suggest that versican may play an essential role both in mesenchymal condensation and in hair induction.

cDNA representational difference analysis of differentially expressed cDNA sequences in human nasopharyngeal carcinoma

OBJECTIVE

To search differentially expressed sequences correlated with pathogenesis of human nasopharyngeal carcinoma (NPC), including the candidates of tumor suppressor genes.

METHODS

Representational difference analysis (RDA) was performed to isolate differentially expressed sequences between cDNA from normal human primary cultures of nasopharyngeal epithelial cells and cDNA from NPC cell line HNE1. The source of differentially expressed products were proved by Southern blot, Northern blot and in situ hybridization. The fragments were cloned with pGEM-T easy kit and sequenced by the chain termination reaction.

RESULTS

Four differentially expressed cDNA fragments were isolated in the fourth subtractive hybridization using cDNA from normal human nasopharyngeal epithelial cells as tester amplicon and cDNA from NPC cell line HNE1 as driver amplicon by cDNA RDA. These differential cDNA fragments revealed that they really came from the tester amplicon and were not expressed or down-regulated in the NPC HNE1 cells. Some of the genes were expressed only in human nasopharyngeal epithelial cells but deleted or down-regulated in the biopsies of NPC. Of these obtained clones, some were the sequences of the human known genes including house-keeping genes, the others represented novel gene sequences.

CONCLUSION

The differentially expressed products including the candidates of tumor-suppressor genes may be associated with the initiation of the NPC.

Increase in apoptosis and concomitant reduction of ischemic lesion volume and evidence for synaptogenesis after transient focal cerebral ischemia in rat treated with staurosporine

We sought to determine whether induction of apoptosis alters an ischemic lesion. Rats were subjected to 2 h of middle cerebral artery occlusion (MCAo) and treated with staurosporine (n=8) or vehicle (n=4). Our data demonstrate that at 22 h after MCAo, staurosporine triggered a significant increase in apoptosis, a reduction of lesion volume and an increase of synaptophysin immunoreactivity, as compared to the control group.

Development of the parasitoid, Cotesia rubecula (Hymenoptera: Braconidae) in Pieris rapae and Pieris brassicae (Lepidoptera: Pieridae): evidence for host regulation

Several recent models examining the developmental strategies of parasitoids attacking hosts which continue feeding and growing after parasitism (=koinobiont parasitoids) assume that host quality is a non-linear function of host size at oviposition. We tested this assumption by comparing the growth and development of males of the solitary koinobiont endoparasitoid, Cotesia rubecula, in first (L1) to third (L3) larval instars of its preferred host, Pieris rapae and in a less preferred host, Pieris brassicae. Beginning 3 days after parasitism, hosts were dissected daily, and both host and parasitoid dry mass was determined. Using data on parasitoid dry mass, we measured the mean relative growth rate of C. rubecula, and compared the trajectories of larval growth of the parasitoid during the larval and pupal stages using non-linear equations. Parasitoids generally survived better, completed development faster, and grew larger in earlier than in later instars of both host species, and adult wasps emerging from P. rapae were significantly larger than wasps emerging from all corresponding instars of P. brassicae. During their early larval stages, parasitoids grew most slowly in L1 P. rapae, whereas in all other host classes of both host species growth to pupation proceeded fairly uniformly. The growth of both host species was markedly reduced after parasitism compared with controls, with the development of P. brassicae arrested at an earlier stage, and at a smaller body mass, than P. rapae. Our results suggest that C. rubecula regulates certain biochemical processes more effectively in P. rapae than in P. brassicae, in accordance with its own nutritional and physiological requirements. Furthermore, we propose that, for parasitoids such as C. rubecula, which do not consume all host tissues prior to pupation, that parasitoid size and host quality may vary independently of host size at oviposition and at larval parasitoid egression.

[Primary study of differentially expressed cDNA sequences in cell line HNE1 of human nasopharyngeal carcinoma by cDNA representational difference analysis]

OBJECTIVE

To search differentially expressed sequences correlated with pathogenesis of human nasopharyngeal carcinoma (NPC), including the candidates of tumor suppressor genes.

METHODS

cDNA representational difference analysis (RDA) was performed to isolate differentially expressed sequences between cDNA from normal human primary cultures of nasopharyngeal epithelial cells and cDNA from NPC cell line HNE1. The sources of differentially expressed products were proved by Southern blot and Northern blot. The fragments were cloned with pGEM-T easy kit and sequenced by the chain termination reaction.

RESULTS

Four differentially expressed cDNA fragments were isolated in the fourth subtractive hybridization using cDNA from normal human primary cultures of nasopharyngeal epithelial cells as tester amplicon and cDNA from NPC cell line HNE1 as driver amplicon by cDNA RDA. These differential cDNA fragments revealed that they really came from the tester amplicon and were not expressed or down-regulated in the NPC HNE1 cells. Of these obtained clones, some are the fragments of the human known genes including house-keeping genes, the others are novel genes.

CONCLUSION

NPC involves alteration of multiple genes. Some of known genes matched with the differentially expressed sequences have an effective suppressive ability on the carcinoma.

[The mechanisms of hyperhomocysteinemia in coronary heart disease]

OBJECTIVE

To identify hyperhomocysteinemia (HHe) as a new and independent risk factor for coronary heart disease (CHD).

METHODS

The association of coronary heart disease (CHD) and lipid, homocysteine (HCY) and the factors related to its metabolisms were examined. The mutation of the 677C-->T transition of MTHFR was determined by PCR-based assay. Whole blood and plasma folate (FA) and plasma vitamin B12(B12), as cofactors of those enzymes, were determined by radioimmunologic assay. Plasma HCY was determined by HPLC.

RESULTS

Patients with CHD confirmed by coronary angiography had increased plasma HCY concentrations (17.1 +/- 3.6 mumol/L, 7.6 +/- 1.2 mumol/L). In patients with MI, HPT and family history (FH) of CHD, plasma HCY increased significantly. Plasma HCY concentrations had significant non-linear inverse relation with plasma FA and B12 concentrations. Homozygous mutants showed higher plasma HCY concentrations. Patients with CHD had increased serum CHOL and VLDL levels, but plasma HCY concentrations were not correlated with serum lipid levels.

CONCLUSION

Hyperhomocysteinemia is an independent risk factor for coronary heart disease.

[Establishment of partial gene expression map of 7q32 in nasopharyngeal carcinoma and primary culture normal nasopharyngeal epithelial cells]

OBJECTIVE

To establish partial gene expression map of 7q32 in nasopharyngeal carcinoma (NPC) cell line, tissues and primary culture normal nasopharyngeal epithelial cells.

METHODS

We detected the expression of 20 ESTs at 7q32 in NPC cell line HNE1,13 NPC biopsies and primary culture normal nasopharyngeal epithelial cells using differential RT PCR and Northern hybridization.

RESULTS

8 ESTs (AA188181, AA13079,N27556, AA031919, N22721, H20825, T91284, AA001936) expressed equally in both of HNE1 and primary culture normal nasopharyngeal epithelial cells; 7 ESTs (T64215, AA025822, R60014,R80002,H06688, R60192,R95096) expressed in neither of them; 3 ESTs (H19830,W72688,AA130630) overexpressed in HNE1 ; and 2 ESTs (AA070437, H90882) overexpressed in primary culture normal nasopharyngeal epithelial cells. W72688 and H19830 each overexpressed in 77%(10/13) of NPC biopsies; AA070437 down-expressed in 30.7% of NPC biopsies.

CONCLUSION

Partial gene expression map of 7q32 in nasopharyngeal carcinoma cell line ,tissues and primary culture normal nasopharyngeal epithelial cells has been established. The up-regulation of W72688, H19830 and down-regulation of AA070437 may be related to the occurrence of NPC.

[Immunoprotection in guinea pigs using DNA recombinant plasmid rpDJt and expressed protein P68 in L. interrogans serovar lai]

Immunoprotection against the infection by Leptospira interrogans serogroup Icterohemorrhagiae serovar lai strain 017 was demonstrated in guinea pigs vaccinated with DNA recombinant plasmid rpDJt and expressed protein P68 derived from genomic library of Leptospira strain 017. Thirty days after active immunization, each group received intraperitoneally (1/2 dose) and subcutaneously (1/2 dose) inoculum of L. interrogans serovar lai stain 017; cultures were adjusted to 5 x 10(8) cells/ml. All guinea pigs were observed for 10 days after challenge. Survival (%) of P68 group was 100(7/7); P23 group was 75(3/4); group rpDJt was 77(10/13); group lack recombinant (control) pT7-7 was 25 (3/12), and group with whole-cell inactivated vaccine was 93(13/14). Although the protective antigen in the leptospires has yet to be determined, it is evident that expressed protein P68 conferred a high degree of immunoprotection in guinea pigs.

Neuronal damage and plasticity identified by microtubule-associated protein 2, growth-associated protein 43, and cyclin D1 immunoreactivity after focal cerebral ischemia in rats

BACKGROUND AND PURPOSE

An objective of therapeutic intervention after cerebral ischemia is to promote improved functional outcome. Improved outcome may be associated with a reduction of the volume of cerebral infarction and the promotion of cerebral plasticity. In the developing brain, neuronal growth is concomitant with expression of particular proteins, including microtubule-associated protein 2 (MAP-2), growth-associated protein 43 (GAP-43), and cyclin D1. In the present study we measured the expression of select proteins associated with neurite damage and plasticity (MAP-2 and GAP-43) as well as cell cycle (cyclin D1) after induction of focal cerebral ischemia in the rat.

METHODS

Brains from rats (n=28) subjected to 2 hours of middle cerebral artery occlusion and 6 hours, 12 hours, and 2, 7, 14, 21, and 28 days (n=4 per time point) of reperfusion and control sham-operated (n=3) and normal (n=2) rats were processed by immunohistochemistry with antibodies raised against MAP-2, GAP-43, and cyclin D1. Double staining of these proteins for cellular colocalization was also performed.

RESULTS

Loss of immunoreactivity of both MAP-2 and GAP-43 was observed in most damaged neurons in the ischemic core. In contrast, MAP-2, GAP-43, and cyclin D1 were selectively increased in morphologically intact or altered neurons localized to the ischemic core at an early stage (eg, 6 hours) of reperfusion and in the boundary zone to the ischemic core (penumbra) during longer reperfusion times.

CONCLUSIONS

The selective expressions of the neuronal structural proteins (MAP-2 in dendrites and GAP-43 in axons) and the cyclin D1 cell cycle protein in neurons observed in the boundary zone to the ischemic core are suggestive of compensatory and repair mechanisms in ischemia-damaged neurons after transient focal cerebral ischemia.

Erythropoietin receptor and STAT5-specific pathways promote SKT6 cell hemoglobinization

Erythrocyte production in mammals is known to depend on the exposure of committed progenitor cells to the glycoprotein hormone erythropoietin (Epo). In chimeric mice, gene disruption experiments have demonstrated a critical role for Epo signaling in development beyond the erythroid colony-forming unit (CFU-e) stage. However, whether this might include the possible Epo-specific induction of red blood cell differentiation events is largely unresolved. To address this issue, mechanisms of induced globin expression in Epo-responsive SKT6 cells have been investigated. Chimeric receptors containing an epidermal growth factor (EGF) receptor extracellular domain and varied Epo receptor cytoplasmic domains first were expressed stably at physiological levels in SKT6 cells, and their activities in mediating induced hemoglobinization were assayed. While activity was exerted by a full-length chimera (EE483), truncation to remove 7 of 8 carboxyl-terminal tyrosine sites (EE372) markedly enhanced differentiation signaling. Moreover, mutation of a STAT5 binding site in this construct (EE372-Y343F) inhibited induced globin expression and SKT6 cell hemoglobinization, as did the ectopic expression of dominant-negative forms of STAT5 in parental SKT6 cells. As in normal CFU-e, SKT6 cells also were shown to express functional receptors for stem cell factor (SCF). To further define possible specific requirements for differentiation signaling, effects of SCF on SKT6 cell hemoglobinization were tested. Interestingly, SCF not only failed to promote globin expression but inhibited this Epo-induced event in a dose-dependent, STAT5-independent fashion. Thus, effects of Epo on globin expression may depend specifically on STAT5-dependent events, and SCF normally may function to attenuate terminal differentiation while promoting CFU-e expansion.

[Allelic loss on chromosome 3p21-26 in nasopharyngeal carcinoma]

OBJECTIVE

To determine the frequency and extent of loss of heterozygosity (LOH) on chromosome 3p in nasopharyngeal carcinoma (NPC).

METHODS

Sixteen loci on chromosome bands 3p21-26 in 24 tumors was studied by using microsatellite analysis.

RESULTS

LOH on 3p21-26 was found in 16 of 24 tumors (66.7%). The highest frequency of the allelic loss was found in two adjacent loci D3S1620(50%, 11/22) and D3S1560 (50%, 9/18). Eight cases showed LOH in one contiguous region and 5 cases in more than one region. Sample 1, 3, 4, 7, 8, 10, 16, 17, 18, 19, and 22 had a contiguous stretch of allelic loss between D3S1297 and D3S1597.

CONCLUSION

The smallest common LOH/deletion region seems likely to lie between D3S1620(3p26.2-26.3) and D3S1560(3p25.3). The allelic loss map defined here will facilitate finer mapping of putative tumor suppressor gene loci and positional cloning of such genes, which may play a role in carcinogenesis of NPC.

[G6PD gene mutations in Guangxi, China]

OBJECTIVE

Fifty-six G6PD-deficient male individuals of the Guangxi origin were investigated at the molecular level to understand the basis of G6PD deficiency.

METHODS

PCR amplified the exons 2,5,6,7,8, 10,11,12 and 13 of the G6PD gene respectively, combined with ASO dot blot hybridization and restriction enzymes digestion methods to screen 10 common Chinese G6PD mutations.

RESULTS

Six mutations were detected, namely cDNA1376(G-->T)(25.0%), cDNA1388(G-->A)(16.1%), cDNA95(A-->G)(19.8%), cDNA592 (C-->T)(7.1%), cDNA1024(C-->T)(1.8%) and cDNA392(G-->T) (1.8%). The unknown mutations accounted for 28.6%. cDNA1311(C-->T),cDNA1360(C-->T),cDNA835(A-->T), cDNA493(A-->G) and cDNA487(G-->A) were not discovered among the cases.

CONCLUSION

The findings may provide some useful informations for physician scientists to get insight into the pathogenesis of G6PD deficiency so as to improve clinical diagnosis, prevention and cure of G6PD deficiency. The results may be of significance in anthropology and geneties as well.

Evidence that HetR protein is an unusual serine-type protease

The hetR gene plays a very important role in cell differentiation of heterocystous cyanobacteria. To understand the mechanism of the hetR gene product in regulation of heterocyst differentiation, the recombinant HetR protein (rHetR) was overproduced in Escherichia coli. Purified rHetR was unstable and degraded easily in solution. Phenylmethanesulfonyl fluoride, a serine-type protease inhibitor, prevented the degradation and was shown to modify covalently rHetR. Dansyl fluoride (DnsF), another serine-type protease inhibitor, also covalently modifies rHetR as shown by electrophoresis and electroblotting of the labeled rHetR and by MS. The labeling of rHetR with phenylmethanesulfonyl fluoride and DnsF was at the same site of rHetR and required Ca2+. S179N-rHetR, a mutant protein from strain 216 of Anabaena PCC 7120, which cannot differentiate heterocysts because of the mutation, was also overproduced and characterized. Although S170N-rHetR still can be labeled with DnsF, no proteolysis was observed, suggesting that Ser179 is involved in proteolytic activity. DnsF-labeled rHetR was digested with trypsin, and the labeled peptide was isolated and sequenced. The labeled peptide matches a sequence from HetR. These results show that HetR is a protease.

Intact, injured, necrotic and apoptotic cells after focal cerebral ischemia in the rat

Middle cerebral artery occlusion (MCAo) leads to brain cell death. However, quantitation of injured brain cells and inflammatory cells after MCAo has not been determined in the rat. Transient (2 h) MCAo was therefore induced in male Wistar rats by means of an intraluminal monofilament. Immunohistochemical and histochemical procedures performed at 46 h after MCAo were used to identify specific cellular populations in ischemic and control rats (n = 11). In the ischemic core of the lesion, approximately 24.7% of cells disappeared. Forty-four point eight percent of parenchymal cells consisted of intact (13.0%) or reversibly injured swollen (7.6%) and scalloped/shrunken dark (24.2%) cells. The percentage of irreversibly damaged cells was 55.2%, and included 49.9% necrotic cells (10.5% red and 39.4% ghost) and 5.4% apoptotic cells. In the inner boundary zone of the lesion, 15.9% of cells disappeared. Viable cells constituted 62.0% of all remaining cells. Neutrophils and macrophages were localized to this area. In the outer boundary zone of the lesion, 9.0% of cells disappeared. Viable cells constituted 91.6% of all remaining cells. The ratio of apoptotic to necrotic cells was 1:9, 1:6, 1:13 in the ischemic core, inner and outer boundary zones, respectively. Our data suggest the presence of three zones within the ischemic lesion: the core, and inner and outer boundaries. At 46 h after 2 h of MCAo the ischemic lesion is highly heterogeneous containing relatively large percentages of morphologically intact cells, suggesting the possibility of an extended window of therapeutic opportunity.

Neutrophil inhibitory factor treatment of focal cerebral ischemia in the rat

The present study was designed to determine whether a hookworm-derived recombinant neutrophil inhibitory factor (rNIF) is neuroprotective when administered after initiation of focal cerebral ischemia in the rat. We measured the rNIF dose-response on cerebral infarct volume, the therapeutic time window, the therapeutic response to permanent ischemia, and whether rNIF treatment delays the maturation of the ischemic lesion (2 days), or reduces cerebral infarct volume at 7 days after middle cerebral artery occlusion (MCAO). MCAO was induced by an insertion of intraluminal 4-0 monofilament nylon suture into internal carotid artery (n=195). We demonstrate a significant neuroprotective effect of rNIF administration 48 h after MCAO in a dose-dependent fashion when treatment was initiated upon reperfusion after 2 h MCAO and maintained until 48 h after MCAO. The beneficial effect was lost under conditions of permanent MCAO. The therapeutic time window is 4 h after MCAO. Brief treatment (6 h) is not sufficient to provide protection for the final ischemic damage. Continuous treatment with a high dose of rNIF for a long duration (7 days) is necessary to achieve maximum neuroprotection.

The expression of P- and E-selectins in three models of middle cerebral artery occlusion

The expression and localization of P- and E-selectins in rat brain (n=126) were examined using immunohistochemical techniques at various time points after induction of middle cerebral artery (MCA) occlusion in the suture, thrombotic and embolic models of stroke. Expression of P- or E-selectin was not observed in brain tissue of sham operated control rats (n=9). P-selectin immunoreactivity was detected as early as 15 min and decreased to control level at 1 h after the onset of the MCA occlusion in all three models. P-selectin then slightly increased at 2 h and peaked at 6 h after MCA occlusion. E-selectin immunoreactivity was first observed at 2 h and peaked at 6 h and 12 h of after MCA occlusion in all three models. P- and E-selectin immunoreactivity was colocalized with von Willebrand factor immunoreactive microvessels. 90.4+/-2.0% of all vessels expressing P-selectin immunoreactivity were 7.5 to 30.0 micron in diameter; 3.6+/-1.4% were contained in vessels smaller than 7.5 micron, and 6.0+/-1.8% were localized in vessels greater than 30.0 micron in diameter. The percent distribution of E-selectin immunoreactive vessels were 75.9+/-2.1% in vessels 7.5 to 30.0 micron in diameter; 23.6+/-2.2% were in vessels smaller than 7.5 micron, and 0.6+/-0.4% were localized in vessels greater than 30.0 micron in diameter. These findings indicate that the temporal profiles of P- and E-selectin expression are independent of these models of MCA occlusion and are consistent with the time course of selectin mediated leukocyte infiltration after focal cerebral ischemia in the rat.

Apoptosis and protein expression after focal cerebral ischemia in rat

We used double staining histochemistry to investigate the relationship between apoptotic cell death and selective protein expression associated with DNA damage (p53, Bax, MDM2, Gadd45), DNA repair (PCNA) and cell cycle proteins (cyclin A, cyclin D, cdk2, cdk4) in rats (n = 6; control rats, n = 5) subjected to transient (2 h) middle cerebral artery occlusion (MCAo) and 46 h of reperfusion. Few apoptotic cells were detected in the non-ischemic hemisphere of control rats. In ischemic animals, scattered apoptotic cells were present in the ischemic core and clustered apoptotic cells were present and localized to the inner boundary zone of the ischemic core. Proteins were preferentially localized to the cellular cytoplasm of control rats and in the non-ischemic hemisphere of rats subjected to MCAo. However, after MCAo these proteins were expressed and were preferentially localized to nuclei within the ischemic lesion. DNA damage induced proteins (wt-p53 and p53-response proteins) were preferentially expressed within apoptotic cells after ischemia. DNA repair proteins and cell cycle proteins were preferentially expressed within morphologically intact cells and in reversibly damaged cells in the ischemic areas. The selective expression of proteins associated with DNA damage, DNA repair and cell cycle observed in morphologically intact cells, ischemic injured cells and apoptotic cells suggests a differential role for these proteins in cell survival and apoptosis after stroke.

Immunoreactivity of cyclin D1/cdk4 in neurons and oligodendrocytes after focal cerebral ischemia in rat

We investigated the expression of cyclin D1 and its kinase, cdk4, after induction of focal cerebral ischemia in the rat. Brain from rats (n = 6) subjected to 2 hours of transient middle cerebral artery occlusion and 46 hours of reperfusion, and control sham-operated (n = 3) and normal (n = 2) rats were processed for dual label immunohistochemical study for cellular identification of the expression of these cell cycle proteins. Antibodies raised against microtubule-associated protein 2 and neuronal specific enolase for neurons, glial fibrillary acidic protein for astrocytes, myelin basic protein for oligodendrocytes and lectin histochemical study with the B4-isolectin for microglia were used for cell type identification. Double staining for DNA fragmentation detection (TUNEL) and expression of cyclin D1 and cdk4 also was performed. Cyclin D1 and cdk4 were selectively expressed in morphologically intact or altered neurons and oligodendrocytes localized to the ischemic tissue. Apoptotic cells were not immunoreactive to cyclin D1 and cdk4 at 46 hours after 2 hours of middle cerebral artery occlusion. The selective expression of cell cycle proteins observed in nonapoptotic ischemic postmitotic neurons and oligodendrocytes suggests a role for these proteins in cell survival after transient focal cerebral ischemia.

[Immunogenecity of expressed protein p68 from recombinant plasmid rpDJt in L. interrogans serovar lai]

There are two types of infection caused by pathogenic microorganisms, intracellular infection and intercellular infection. Infection of pathogenic leptospira is an intercellular infection. The immunological reaction of host to intercellular infection is unique. The potential immunogen of an expressed protein should meet three criteria: it can be degraded (by antigen-present cells in the host); it should have antigenic epitope which can be recognized by specific antibodies and have at least one epitope that can be recognized by an MHC II protein and T cell receptor. In this study we report the cloning of an L. interrogans protein in plasmid rpDJt and the immunogencity of the expressed protein derivative. A genomic library of L. interrogans serovar lai strain 017 was constructed with the plasmid vector pUC18. Recombinant plasmids, designated pDJH2 and pDJ8 were screened from the bank. EcoRI-inserted fragment of 1. 9 kb recombinant DNA of pDJH2 was ligated into T7 RNA polymerase/promoter vectors (pT7-7). Then they were transformed into E. coli JM109 (De3), one of subclones, designated rpDJt was achieved. SDS-PAGE showed that the molecular weights of expression proteins were 68 kd and 23 kd respectively, designated p68 and p23. Purifying and isolating p68 and p23, we separated them from SDS-Polyacrylamide gels by using Side-Strip method. After fragmenting and electroeluting, p68 and p23 were injected into guinea pigs and rabbits. An extremely strong immune response to p68 was obtained since an anti-p68 antibody response could be detected to a dilution 1:524,288 (guinea pigs) and 1:262,144 (rabbits) by ELISA while anti-P23 antibody being 1:1024 (the same to guinea pigs and rabbits). The results of improved MTT and conA 3HTdR transformation methods showed the activities and proliferation of Th-cells were increased in guinea pigs after p68 immunization (IL-6, 83.25 IU/ml, IL-2, 28.75 IU/ml; RPI, 2.04, SI, 65.62%) Thlymphocyte existed in two subclasses, the Th1- and Th2-cells. A major role of Th2-cells is to "help" B-cells differentiate, replicate, and secrete antibody. The properties of these interactions explain why p68 makes good antigen and p23 does not. The antigens responsible for eliciting the production of protective antibodies are not known; however, several outer membrane proteins on L. interrogans are candidates for vaccine. Our results suggest that expresion protein p68 from recombinants (rpDJt) may be a candidate for gene engineered subunit vaccine for Leptospirosis.