A previously undescribed intron and extensive 5' upstream sequence, but not Phox2a-mediated transactivation, are necessary for high level cell type-specific expression of the human norepinephrine transporter gene

The synaptic action of norepinephrine is terminated by NaCl-dependent uptake into presynaptic noradrenergic nerve endings, mediated by the norepinephrine transporter (NET). NET is expressed only in neuronal tissues that synthesize and secrete norepinephrine and in most cases is co-expressed with the norepinephrine-synthetic enzyme dopamine beta-hydroxylase (DBH). To understand the molecular mechanisms regulating human NET (hNET) gene expression, we isolated and characterized an hNET genomic clone encompassing approximately 9. 5 kilobase pairs of the 5' upstream promoter region. Here we demonstrate that the hNET gene contains an as-yet-unidentified intron of 476 base pairs within the 5'-untranslated region. Furthermore, both primer extension and 5'-rapid amplification of cDNA ends analyses identified multiple transcription start sites from mRNAs expressed only in NET-expressing cell lines. The start sites clustered in two subdomains, each preceded by a TATA-like sequence motif. As expected for mature mRNAs, transcripts from most of these sites each contained an additional G residue at the 5' position. Together, the data strongly support the authenticity of these sites as the transcriptional start sites of hNET. We assembled hNET-chloramphenicol acetyltransferase reporter constructs containing different lengths of hNET 5' sequence in the presence or the absence of the first intron. Transient transfection assays indicated that the combination of the 5' upstream sequence and the first intron supported the highest level of noradrenergic cell-specific transcription. Forced expression of the paired-like homeodomain transcription factor Phox2a did not affect hNET promoter activity in NET-negative cell lines, in marked contrast to its effect on a DBH-chloramphenicol acetyltransferase reporter construct. Together with our previous studies suggesting a critical role of Phox2a for noradrenergic-specific expression of the DBH gene, these data support a model in which distinct, or partially distinct, molecular mechanisms regulate cell-specific expression of the NET and DBH genes.

Immune-stimulating properties of polysaccharides from Phellodendri cortex (Hwangbek)

Heteropolysaccarides were isolated from the Korean medicinal plant, Phellodendri cortex (Hwangbek), by hot water and alkali extractions. The extracted polysaccharides were fractionated into eight fractions and they are mainly composed of D-N-acetylglucosamine, D-galactose, D-mannose, and D-glucose. Among the polysaccharide fractions, Fr.-2 showed a potent B-lymphocyte-stimulating activity in a system using polyclonal antibody forming cells in C57BL/6XC3H mice at dosages of 2-10 mg. On the basis of their solubility in aqueous ethanol, four fractions of Fr.-2-1 to Fr.-2-4 were further obtained from the Fr.-2, and Fr.-2-3 was divided into Fr.-2-3-1, 2, 3, and 4 by DEAE cellulose chromatography. The main activity was found in Fr.-2-3-2, which contained 100% (w/w) of carbohydrates and further purified to Fr.-2-3-2-2 by gel filtration chromatography using TSK Gel HW50S. Fr.-2-3-2-2, having a molecular weight of about 230 kDa, showed the highest B-cell-stimulating activity and the half-maximal concentration for B-lymphocyte-stimulating activity was ca. 2.2 microg/ml.

Fas ligand and Fas are expressed constitutively in human astrocytes and the expression increases with IL-1, IL-6, TNF-alpha, or IFN-gamma

Fas ligand (FasL) and Fas are mediators of apoptosis, which are implicated in the peripheral deletion of autoimmune cells, activation-induced T cell death, and cytotoxicity mediated by CD8+ T cells. Fas is also believed to be involved in several central nervous system diseases, but until now, the effector cells expressing FasL in the brain have not been identified. We investigated the expression levels of Fas and FasL with the stimulation of cytokines and the possible effector cells targeting Fas-bearing cells. Our data demonstrated that: 1) FasL is expressed constitutively on astrocytes taken from a fetus or an adult and that its expression increases when these cells are treated with IL-1, IL-6, or TNF-alpha in which the pretreatment of IFN-gamma triggers astrocytes to express more FasL; 2) astrocytes induce apoptosis in MOLT-4 cells through FasL; 3) Fas is also expressed constitutively and is up-regulated by IL-1, IL-6, or TNF-alpha in which the pretreatment of IFN-gamma triggers astrocytes to express more Fas; 4) apoptosis occurs when fetal astrocytes are treated with agonistic anti-Fas IgM Ab after culture with IFN-gamma and TNF-alpha; and 5) TNF-related apoptosis inducing ligand is up-regulated in fetal astrocytes with stimuli of IL-1 or TNF-alpha. These findings suggest a possible role of astrocytes in the induction of apoptosis in central nervous system diseases.

Inhibitory effects of streptozotocin, tumor necrosis factor-alpha, and interleukin-1beta on glucokinase activity in pancreatic islets and gene expression of GLUT2 and glucokinase

Treatment of streptozotocin (ST), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) resulted in destroying insulin-secreting beta-cells of pancreatic islets and impairment of islet glucose oxidation and glucose-induced insulin secretion. IL-1beta and TNF-alpha inhibited insulin release and glucose utilization and oxidation. It was shown that the inhibitory effects of ST, IL-1beta, and TNF-alpha were due to impaired glucokinase activity. Glucokinase activity was severely impaired by ST, IL-1beta, and TNF-alpha treatments, as confirmed by assaying enzymes and nucleotides associated with glycolysis and glucose oxidation. On the other hand, nitric oxide was a factor of the deleterious effects of IL-1beta, TNF-alpha, and ST on pancreatic islets. Incubation of mouse pancreatic islets with ST at various concentrations of impairing insulin secretion resulted in generation of nitrite, stimulation of islet guanylyl cyclase and accumulation of cGMP, and inhibition of pancreatic islet mitochondrial aconitase activity to degree similar to those raised by IL-1beta and TNF-alpha. When the effects of IL-1beta and TNF-alpha on the gene expression of pancreatic GLUT2 and glucokinase were examined, the level of GLUT2 and glucokinase mRNA in pancreatic islets was significantly decreased. This suggested that IL-1beta and TNF-alpha downregulate gene expression of GLUT2 and glucokinase in pancreatic beta-cells.

CD40 activation boosts T cell immunity in vivo by enhancing T cell clonal expansion and delaying peripheral T cell deletion

In this report we show that activation of APC with an agonist anti-CD40 mAb profoundly alters the behavior of CD4 T cells in vivo. Stimulation of mice with anti-CD40 2 days before, but not 1 day after, administration of superantigen (SAg) enhanced CD4 and CD8 T cell clonal expansion by approximately threefold. Further, CD40 activation also delayed peripheral T cell deletion after activation. Dying, activated T cells were quantitated by detecting extracellular phosphatidylserine with concomitant staining for SAg-reactive T cells using a TCR Vbeta-specific mAb. Upon close examination, it was shown that CD40 activation delayed the death of the activated T cells. Additionally, it was found that enhanced survival of CD4 T cells was equally dependent on APC expression of B7-1 and B7-2. This is in contrast to CD8 T cells, which did not depend as much on B7-1 as B7-2. Thus, CD40 activation indirectly promotes T cell growth and delays the death of SAg-stimulated CD4 T cells in vivo. These data suggest that one way CD40 activation promotes a more robust immune response is by indirectly increasing the production of effector T cells and by keeping them alive for longer periods of time.

Calculation of effective doses for broad parallel photon beams

Values of effective dose (E) were calculated for the entire range of incident directions of broad parallel photon beams for selected photon energies using the Monte Carlo N-Particle (MCNP) transport code with a hermaphroditic phantom. The calculated results are presented in terms of conversion coefficients transforming air kerma to effective dose. This study also compared the numerical values of E and H(E) over the entire range of incident beam directions. E was always less than H(E) considering all beam directions and photon energies, but the differences were not significant except when a photon beam approaches some specific directions (overhead and underfoot). This result suggests that the current H(E) values can be directly interpreted as E or, at least, as a conservative value of E without knowing the details of irradiation geometries. Finally, based on the distributions of H(E) and E over the beam directions, this study proposes ideal angular response factors for personal dosimeters that can be used to improve the angular response properties of personal dosimeters for off-normal incident photons.

Expression of p53 protein in rheumatoid arthritis synovium. An immunohistochemical analysis

OBJECTIVES

Mutation of p53 may play a role in manifestation of rheumatoid arthritis synovium, but several studies on p53 expression in synovial tissues of rheumatoid arthritis showed conflicting results. We investigated the amount and pattern of p53 positive cells in rheumatoid arthritis synovium, in comparison with osteoarthritis synovium, by using immunohistochemistry with two other monoclonal antibodies for p53.

METHODS

Synovial tissues from 9 patients with rheumatoid arthritis and 5 patients with osteoarthritis were examined for p53 expression by immunohistochemistry with 2 monoclonal antibodies for p53, DO-1 and DO-7. Histologic features of inflammation were also scored and compared with p53 expression.

RESULTS

There was no significant difference between inflammatory scores in both groups. In the synovial tissues of rheumatoid arthritis patients, p53 positive cells were detected in 3 out of 9 samples(33%) and p53 expressions were restricted to inflammatory mononuclear cells, but synovial lining cells, subsynovial fibroblast-like cells and vascular endothelial cells were p53 negative. p53 expressions in osteoarthritis synovial tissues as control were observed in 2 out of 5 samples(40%) and the amount and pattern of p53 positive cells were comparable to those seen in rheumatoid arthritis synovial tissues. There was no demonstrable correlation between the synovial tissues of both groups with respect to inflammation scores and expression of p53 protein.

CONCLUSION

Our findings suggest that altered p53 expression may not play a significant role in the manifestation of rheumatoid arthritis synovium. However these data need to be strengthened by increasing the number of samples and molecular biology approaches.

Chemokines: signal lamps for trafficking of T and B cells for development and effector function

Chemokines can act as signal lamps for trafficking of lymphocytes at the important crossing points of lymphoid tissues. Lymphoid progenitors at different differentiation stages are differentially localized in primary lymphoid tissues and have differential responsiveness to thymic or bone marrow chemokines: SDF-1, CKbeta-11/MIP-3beta/ELC, SLC/6Ckine/Exodus2, MIP-1beta, and TECK. Naive T cells and B cells circulate to secondary lymphoid tissues for possible activation. Chemokines, SDF-1, SLC/6Ckine/Exodus2, CKbeta-11/MIP-3beta/ELC, BLC/BCA-1, and DC-CK1/PARC, are expressed in the specialized microenvironments of secondary lymphoid tissues and regulate the migration of naive lymphocytes. Effector lymphocytes express a different set of chemokine receptors from naive lymphocytes. T helper (Th) 0 and 1 cells predominantly express CXCR3 and CCR5, whereas Th2 cells express CCR3, CCR4, and CCR8, which, with other factors such as expression patterns of adhesion molecules, likely determine the tissue-specific infiltration of effector lymphocytes.

Truncated particles produced in fish surviving infectious hematopoietic necrosis virus infection: mediators of persistence?

Infectious hematopoietic necrosis virus (IHNV) is a rhabdovirus that produces an acute, lethal infection in rainbow trout (Oncorhynchus mykiss). Fish that survive infection cease to produce detectable infectious virus at approximately 46 days after infection, yet there is evidence that survivor fish continue to harbor virus particles (B. S. Drolet, P. P. Chiou, J. Heidel, and J. C. Leong, J. Virol. 69:2140-2147, 1995). In an effort to determine the biological function of these particles, the kidneys and livers from IHNV survivors were harvested and divided into samples for nested reverse transcriptase PCR analysis and explant culture. Sequences for the IHNV nucleoprotein and polymerase genes were detected in 50 and 89%, respectively, of the organs from survivor fish. When explant tissue cultures were infected with purified standard IHNV, the liver tissues from survivor fish produced up to 10-fold less virus than naive control fish liver tissues. In addition, immunosorbent electron microscopy analysis of the supernatant media from the cultured explants of survivor fish revealed truncated particles, whereas the control tissue supernatants contained only standard viral particles. These results suggest that the truncated IHNV particles observed in persistently infected fish are defective interfering particles that may mediate virus persistence.

Effects of radical scavengers and antioxidant on ischemic acute renal failure in rabbits

This study was undertaken to determine whether reactive oxygen species (ROS) are involved in the pathogenesis of ischemic acute renal failure (IARF) in rabbits. Renal ischemia was induced by clamping bilateral renal arteries for 60 min. Animals were pretreated with combination of xanthine oxidase inhibitor (allopurinol), hydrogen peroxide scavenger (catalase), and hydroxyl radical scavenger (sodium benzoate). Serum creatinine level significantly increased 24 h after ischemia and remained higher to 72 h. Ischemia caused a reduction of GFR and an increase of FENa. Such changes were significantly attenuated by scavenger pretreatment. The uptake of p-aminohippurate in cortical slices and microsomal Na(+)-K(+)-ATPase activity were depressed in kidneys subjected to 72 h of reflow following ischemia, indicating impairment of tubular transport function, which were significantly attenuated by scavenger treatment. Renal blood flow 72 h after reflow was markedly reduced and it was restored by scavenger pretreatment. When animals were pretreated with a potent antioxidant DPPD, lipid peroxidation in cortex and medulla was significantly inhibited. However, ischemia-induced impairment of renal function was not attenuated by pretreatment of the antioxidant. These results suggest that radical scavengers may exert a protective effect against ischemia acute renal failure by other actions rather than ROS scavenging. Thus, the data do not support involvement of ROS in IARF in rabbits.

Molecular Cloning and Expression of an Endo-β-1,4-D-glucanase I (Avicelase I) Gene from Bacillus cellulyticus K-12 and Characterization of the Recombinant Enzyme

Bacillus cellulyticus K-12 Avicelase (Avicelase I; EC 3.2.1.4) gene (ace A) has been cloned in Escherichia coli by using the vector pT7T3U19 and HindIII- HindIII libraries of the chromosomal inserts. The libraries were screened for the expression of avicelase by monitoring the immunoreaction of the antiavicelase (immunoscreening). Positive clones (Ac-3, Ac-5, and Ac-7) contained the identical 3.5-kb HindIII fragment as determined by restriction mapping and Southern hybridization, and expressed avicelase efficiently and constitutively using its own promoter in the heterologous host. From the immunoblotting analysis, a polypeptide that showed a carboxymethylcellulase (CMCase) activity with an Mr of 64,000 was detected. The recombinant endo 1,4-beta-D-glucanase I was purified to homogeneity from an intracellular fraction of E. coli by DEAE-Toyopearl M650, Phenyl Toyoperal M650, and TSK gel HW50S chromatography. The enzyme had a monomeric structure, its relative molecular mass being 65 kDa by gel filtration and 64 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The pI was 5.3 and the optimal pH was 4.6, and the enzyme was stable at pH 4.0-10.5. The enzyme had a temperature optimum of 50 degrees C and was stable at 55 degrees C for 48 h, and retained approx 20% of its activity after 30 min at 70 degrees C. It showed high activity toward carboxymethylcellulose (CMC) as well as p-nitrophenyl-beta-D-cellobioside, 4-methylumbelliferyl cellobioside, Avicel, filter paper, and some cellooligosaccharides. Km values for CMC and Avicel were 7.6 and 85.2 mg/mL, respectively, whereas Vmax values were 201 and 9.2 micromol x min(-1) x mg(-1), respectively. Cellotetraose (G4) was preferentially cleaved into cellobiose (G2) and cellopentaose (G5) was cleaved into G2 + cellotriose (G3), whereas cellohexaose (G6) was cleaved into G4 + G2 and, to a lesser extent, into G3 + G3. G3 was not cleaved at all. G2 was the main product of Avicel hydrolysis. G2 inhibited whereas Mg++ stimulated the activity of CMCase and Avicelase. Hydrolysis of CMC took place with a rapid decrease in viscosity but a slow liberation of reducing sugars. Based on these results, it appeared that the cellulase should be regarded as endo type, although it hydrolyzed Avicel.

Thyroid hormone stimulates basal and interleukin (IL)-1-induced IL-6 production in human bone marrow stromal cells: a possible mediator of thyroid hormone-induced bone loss

It is well known that excessive thyroid hormone in the body is associated with bone loss. However, the mechanism by which thyroid hormone affects bone turnover remains unclear. It has been shown that it stimulates osteoclastic bone resorption indirectly via unknown mediators secreted by osteoblasts. To determine if interleukin-6 (IL-6) or interleukin-11 (IL-11) could be the mediator(s) of thyroid hormone-induced bone loss, we studied the effects of 3,5,3'-tri-iodothyronine (T3) on basal and interleukin-1 (IL-1)-stimulated IL-6/IL-11 production in primary cultured human bone marrow stromal cells. T3 at 10(-12)-10(-8) M concentration significantly increased basal IL-6 production in a dose-dependent manner. It also had an additive effect on IL-1-stimulated IL-6 production, but failed to elicit a detectable effect on basal or IL-1-stimulated IL-11 production. Treatment with 17beta-estradiol (10(-8) M) did not affect the action of T3 on IL-6/IL-11 production. These results suggest that thyroid hormone may stimulate bone resorption by increasing basal and IL-1-induced IL-6 production from osteoblast-lineage cells, and these effects are independent of estrogen status.

Cloning of the genomic sequence encoding a processed adenylate kinase 2 pseudogene

A chromosomal DNA sequence harboring a processed AK2B pseudogene was isolated from a human genomic library. It was a variant of the AK2B gene sequence including several point mutations, deletions, and insertions. The nucleotide sequence of the ORF of the AK2B pseudogene predicted a truncated form of the AK2B mutant suggesting that the processed pseudogene is nonfunctional. A repetitive sequence, AAAAGAGAG, found in the 5' and 3' flanking regions of the pseudogene and the poly(A) tract in the 3' end junction suggest that a mRNA of AK2B may have been converted to the processed pseudogene by retrotransposition events. Previously, it was suggested that an adenylate kinase (AK) 2 related gene on chromosome 2, confirmed by Southern analysis using somatic cell hybrid cell lines, may be a processed pseudogene. It is proposed that the processed pseudogene isolated in this study may be the AK2 related nonfunctional gene localized on human chromosomes 2.

Effects on substrate reduction of substitution of histidine-195 by glutamine in the alpha-subunit of the MoFe protein of Azotobacter vinelandii nitrogenase

Studies of the substrate-reducing capabilities of an altered nitrogenase MoFe protein (alpha-195(Gln) instead of alpha-195(His)) from a mutant of Azotobacter vinelandii show, contrary to an earlier report [Kim, C.-H., Newton, W. E., and Dean, D. R. (1995) Biochemistry 34, 2798-2808], that the alpha-195(Gln) MoFe protein can reduce N2 to NH3 but at a rate that is <2% of that of the wild type. The extent of effective binding of N2 by this altered MoFe protein, as monitored by the inhibition of H2 evolution, is markedly increased as temperature is lowered but virtually eliminated at 45 degreesC. This inhibition of H2 evolution results in an increase in the ATP:2e- ratio, i.e., the number of molecules of MgATP hydrolyzed for each electron pair transferred to substrate, from ca. 5 (the wild-type level) at 45 degreesC to nearly 25 at 13 degreesC. Like wild-type nitrogenase, the N2 inhibition of H2 evolution reaches a maximum at an Fe protein:MoFe protein molar ratio of ca. 2.5, suggesting that a highly reduced enzyme may not be necessary for N2 binding. N2 binding to the alpha-195(Gln) MoFe protein retains a hallmark of the wild type by producing HD under a mixed N2/D2 atmosphere. The rate of HD production and the fraction of total electron flow allocated to HD are similar to those for wild-type nitrogenase under the same conditions. However, the electrons forming HD do not come from those normally producing NH3 (as occurs in the wild type) but are equivalent to those whose evolution as H2 had been inhibited by N2. N2 also inhibits C2H2 reduction catalyzed by the alpha-195(Gln) nitrogenase. This inhibition is relieved by added H2, resulting in a lowering of the elevated ATP:2e- ratio to that found under Ar. With solutions of NaCN, which contain both the substrate, HCN, and the inhibitor, CN-, reduction of HCN is not impaired with the alpha-195(Gln) nitrogenase, but the inhibition by CN- of total electron flow to substrate, which is observed with the wild-type MoFe protein, is completely absent. Unlike that of the catalyzed reduction of H+, HCN, or C2H2, the extent of azide reduction to either N2 or N2H4 is markedly decreased (to 5-7% of that of the wild type) with the alpha-195(Gln) nitrogenase. Azide, like N2, inhibits H2 evolution and increases the ATP:2e- ratio. Both effects are freely reversible and abolished by CO. Added D2 does not relieve either effect, implying that N2 produced from N3- is not the inhibitory species. The correlation between the extremely low rates of reduction for both N2 and azide by the alpha-195(Gln) nitrogenase and their common ability to inhibit H2 evolution suggests that alpha-histidine-195 may be an important proton conductor to the FeMo cofactor center and specifically required for reduction of these two substrates.

High serum lipoprotein(a) levels in Korean type 2 diabetic patients with proliferative diabetic retinopathy

OBJECTIVE

To examine the possible association between serum lipoprotein(a) [Lp(a)] concentration and proliferative diabetic retinopathy (PDR) in Korean patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 412 Korean outpatients with type 2 diabetes were examined. Diabetic retinopathy was determined by an ophthalmologist using fundoscopic examination. Serum Lp(a) levels were measured by two-site sandwich enzyme-linked immunosorbent assay.

RESULTS

The patients with PDR had higher serum Lp(a) levels than those with no diabetic retinopathy or with nonproliferative diabetic retinopathy (NPDR). Multiple logistic regression analysis showed that high serum Lp(a) levels and the presence of diabetic nephropathy were independent variables having a statistically significant association with PDR.

CONCLUSIONS

Korean type 2 diabetic patients with PDR had higher serum Lp(a) levels versus those with no diabetic retinopathy or with NPDR. Although these results suggest that Lp(a) might play a role in the occlusion of retinal capillaries leading to PDR, further prospective studies are required to prove the causal relationship.

Cloning and expression of cDNA for a human Sia alpha 2,3Gal beta 1, 4GlcNA:alpha 2,8-sialyltransferase (hST8Sia III)

The cDNA encoding human Sia-alpha2,3-Gal-beta1,4-GlcNAc-R:alpha2, 8-sialyltransferase, hST8Sia III, was isolated by screening of a human brain cDNA library with polymerase chain reaction-amplified DNA probe generated from the sequence of mouse ST8Sia III (mST8Sia III) and by 5' rapid amplification of cDNA ends of mRNA isolated from human brain tissues. Comparative analysis of the predicted protein-coding region between our cloned hST8Sia III and mST8Sia III showed 92 and 96% identities in the nucleotide and the amino acid sequence, respectively. The soluble hST8Sia III protein expressed in COS-7 showed an extremely high catalytic activity of transferring sialic acid through alpha2,8-linkage to intact fetuin glycoprotein, whereas the transferring activity was completely undetectable toward either alpha2,6-sialylated glycoprotein or desialylated glycoprotein acceptors. Northern analysis of hST8Sia III showed that the transcript corresponding to 11 kb was expressed in both human fetal and adult brain, while the expression of the 5.5-kb transcript was restricted to fetal liver, indicating that the expression of hST8Sia III is developmentally and tissue-specifically regulated.

Interferon-inducible Mx proteins in fish

Mx proteins are members of a family of interferon-inducible genes expressed when cells are treated with double-stranded RNA or virus infection. These proteins are important components of the antiviral response and form the first line of the body's defense against virus infections. The exact mechanism of action for these proteins has not been discovered, but mice missing the Mx genes are extremely sensitive to influenza virus infection. Mammals have between two and three Mx genes whose functions may vary with regard to the inhibition of a specific virus, cellular localization, and activity. The cDNA of three rainbow trout Mx proteins has been cloned and a comparison of their sequences with that of avian and mammalian species reveals striking conservation of domains. They all maintain the tripartite ATP/GTP binding domain and the dynamin family signature in the amino terminal half of the protein. In the carboxyl terminal half of the Mx proteins are the localization signals and the leucine zipper motifs which account for the trimerization of Mx in the cell. Like the rat and human Mx proteins, the different trout Mx proteins exhibit distinctly different immunohistochemical staining patterns in cells transfected with plasmids expressing RBTMx1, RBTMx2, or RBTMx3. To date, the antiviral function of the trout Mx proteins has not been satisfactorily established.

Soft shell clams Mya arenaria with disseminated neoplasia demonstrate reverse transcriptase activity

Disseminated neoplasia (DN), a proliferative cell disorder of the circulatory system of bivalves, was first reported in oysters in 1969. Since that time, the disease has been determined to be transmissible through water-borne exposure, but the etiological agent has not been unequivocally identified. In order to determine if a viral agent, possibly a retrovirus, could be the causative agent of DN, transmission experiments were performed, using both a cell-free filtrate and a sucrose gradient-purified preparation of a cell-free filtrate of DN positive materials. Additionally, a PCR-enhanced reverse transcriptase assay was used to determine if reverse transcriptase was present in tissues or hemolymph from DN positive soft shell clams Mya arenaria. DN was transmitted to healthy clams by injection with whole DN cells, but not with cell-free filtrates prepared from either tissues from DN positive clams, or DN cells. The cell-free preparations from DN-positive tissues and hemolymph having high levels of DN cells in circulation exhibited positive reactions in the PCR-enhanced reverse transcriptase assay. Cell-free preparations of of hemolymph from clams having low levels of DN (<0.1% of cells abnormal), hemocytes from normal soft shell clams, and normal soft shell clam tissues did not produce a positive reaction in the PCR enhanced reverse transcriptase assay.

Paired-like homeodomain proteins, Phox2a and Phox2b, are responsible for noradrenergic cell-specific transcription of the dopamine beta-hydroxylase gene

Recently, a murine paired-like homeobox gene, Phox2a, has been identified whose product is critical for the development of several major noradrenergic neuron populations, including the locus coeruleus. In noradrenergic neurons, dopamine beta-hydroxylase (DBH) is a hallmark protein and catalyzes the conversion of dopamine to noradrenaline. Our previous studies have shown that a composite promoter (domain IV), residing at -185 to -150 bp upstream of the transcription start site, is critical for DBH transcription and is comprised of multiple cis-acting elements, including a cyclic AMP response element, a YY1 binding site, and two core motifs of the homeodomain (HD)-binding site. Here, we show that the HD-binding site residing within domain IV is a noradrenergic-specific cis-acting element. In contrast, the cyclic AMP response element is active in all cell lines tested. We provide evidence that Phox2a is expressed only in DBH-positive cell lines and interacts with the HD-binding site. Forced expression of Phox2a robustly activates DBH promoter activity in DBH-negative cell lines (>10-fold), but increased it only marginally (<50%) in DBH-positive cell lines. Furthermore, another protein factor with an identical HD, Phox2b, also activates DBH transcription with an efficiency comparable to that of Phox2a. In contrast, neither Phox2a nor Phox2b was able to transactivate tyrosine hydroxylase transcription, indicating that these transcription factors differentially activate catecholamine-synthesizing gene transcription. Together with the Phox2a knockout experiment, the studies described here make Phox2a and Phox2b the first strong candidate transcription factors for determining a neurotransmitter phenotype in vertebrates.

Characterization of two frizzled8 homologues expressed in the embryonic shield and prechordal plate of zebrafish embryos

We have isolated and characterized two complete cDNA clones, Zfz8a and Zfz8b, which encode zebrafish Frizzled (Fz) homologues. The predicted protein sequences, spanning 579 and 576 amino acid residues for ZFz8a and ZFz8b, respectively, were highly homologous (78%) to each other and contained an extracellular cysteine-rich domain and seven transmembrane domains that are well conserved in Fz receptor protein members. In comparison with other Fz family members, ZFz8a and ZFz8b showed the highest homology with mouse Fz8 (MFz8), sharing 84 and 76% amino acid identity, respectively. The presence of Zfz8a and Zfz8b transcripts was detected by in situ hybridization in zebrafish embryos from the 512 cell stage, and their appearance in the future dorsal region could be observed before embryos reached the 30% epiboly stage. At shield stage, Zfz8a transcripts were expressed in both epiblast and shield whereas expression of Zfz8b was only detected in the embryonic shield. During gastrula stages, both Zfz8a and Zfz8b transcripts were found in anterior dorsal regions of the involuting mesendoderm (future prechordal plate). By the 2- to 3-somite stage, expression of both Zfz8a and Zfz8b was restricted to the prechordal plate and prospective anterior neurectoderm, although expression of the Zfz8a gene was no longer present in the most anterior portion of the prechordal plate, the polster. In one-eyed pinhead mutant embryos, which lack prechordal plate, both Zfz8a and Zfz8b transcripts were reduced, confirming the prechordal plate specificity of Zfz8a and Zfz8b gene expression. These results provide an additional evidence supporting the role of Wnt signaling in organizer-mediated axial patterning.

Extracellular and cytosolic iron superoxide dismutase from Mycobacterium bovis BCG

Two forms of iron superoxide dismutase (SOD) were purified from cell extract (CE) and culture filtrate (CF) of Mycobacterium bovis BCG, respectively. The molecular weight of both enzymes was estimated to be approximately 84,000 by gel filtration, whereas that of their subunits was 21,500, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that each of purified enzymes is composed of four identical subunits. The specific activities of CE SOD and CF SOD were 3,850 and 4,040, respectively. The purified enzymes were not joined by disulfide bonds and were, to some extent, resistant to sodium dodecyl sulfate. Their activities were lost by H2O2, but not by azide and cyanide, indicating iron SODs. Enzyme activities were detectable over a broad range of pHs, from 5.0 to 9.0, and were stable for 6 months at -20 degreesC. Each value of pI was 4.5. In Western blots, both enzymes reacted with sera of tuberculosis patients, but not with normal sera. The N-terminal amino acid sequences of CE SOD and CF SOD were the same, suggesting that there is no N-terminal signal sequence.

Macrophage-inflammatory protein-3 beta/EBI1-ligand chemokine/CK beta-11, a CC chemokine, is a chemoattractant with a specificity for macrophage progenitors among myeloid progenitor cells

Chemoattractants are potential factors influencing cell migration. Stromal cell-derived factor-1, a CXC chemokine, is the only chemokine reported to have chemotactic activity for hemopoietic progenitor cells (HPC). We report in this work another chemokine of the CC subfamily, which is chemotactic for HPC. Macrophage-inflammatory protein (MIP)-3 beta/EBI1-ligand chemokine/CK beta-11 attracted bone marrow and cord blood CD34+ cells. In contrast to stromal cell-derived factor-1, which attracts multiple types of HPC, MIP-3beta attracted mainly CFU granulocyte macrophage, but not other HPC such as burst-forming unit erythrocyte or CFU granulocyte, erythrocyte, macrophage, and megakaryocyte. Chemoattracted CD34+ cells formed CFU granulocyte macrophage-like colonies, which were morphologically determined as large macrophages. These progenitors were selectively responsive to stimulation by macrophage CSF, demonstrating that MIP-3 beta attracts macrophage progenitors. Expression of CCR7, the receptor for MIP-3 beta, was detected at a mRNA level in the attracted CD34+ cells as well as input CD34+HPC. Expression of MIP-3 beta mRNA was not constitutive, but was inducible in bone marrow stromal cells by inflammatory agents such as bacterial LPS, IFN-gamma, and TNF-alpha. Taken together, our findings suggest that MIP-3 beta is expressed in the bone marrow environment after induction with certain inflammatory cytokines and LPS, and may play a role in trafficking of macrophage progenitors in and out of the bone marrow in inflammatory conditions.

Telomerase activity and telomere lengths in various cell lines: changes of telomerase activity can be another method for chemosensitivity evaluation

For the cancer cells which have overcome the second mitotic clock (M2), activated telomerase is essential and used as another marker of immortality. Many trials had been initiated to target telomerase, which is known to be specific to tumors. To determine the best in vitro cell system for testing the efficacy of telomerase inhibitors, we evaluated the telomerase activity of various cancer cell lines and measured their telomere lengths. We also treated some cancer cell lines with adriamycin and measured the changes of telomerase activity. Telomerase activity was evaluated in various cell lines with the TRAP (telomeric repeat amplification protocol) assay. Telomerase activity was calculated and translated into arbitrary units by computer-assisted densitometry with the control of telomerase activity in the 293 control cell line. Also, terminal restriction fragment lengths were measured using Southern blotting. We also measured telomerase activity and telomere lengths in 11 benign breast tumor tissues and 19 paired stomach cancer and normal tissues. Cancer cell lines treated with adriamycin we evaluated for changes of telomerase activity and the cell proliferation by MTT assay and dye exclusion test. Telomerase activity of cell lines was 95.3 24.1 unit with a range of 27.6-129.6 unit, while the telomere lengths of those cell lines were variable from 5.0 to 10.4 kbp with a median of 6 kbp. In 11 cancer cell lines which were not yet firmly established, we could not detect any telomerase activity. Low telomerase activity was detected in only 2 benign tumor tissues of breast with a median telomere length of 8.8 (7-10.5) kbp. Among paired 19 gastric cancer and normal tissues, only 7 cancer tissues showed weak telomerase activity. After adriamycin treatment, telomerase activity in YCC-S-1, YCC-S-3, MCF-7 and MCF-7/ADR was decreased in accordance with the changes of the cell numbers. Telomerase is specific to cancer tissues and is expressed differently from organ to organ. Telomerase activity by TRAP assay could be used as a chemosensitivity assay.

A novel homeobox gene, dharma, can induce the organizer in a non-cell-autonomous manner

The formation of Spemann organizer is one of the most important steps in dorsoventral axis determination in vertebrate development. However, whether the organizer forms autonomously or is induced non-cell-autonomously is controversial. In this report we have isolated a novel zebrafish homeobox gene, dharma, capable of inducing the organizer ectopically. The expression of dharma was first detected in several blastomeres at one side of the margin soon after the mid-blastula transition and continued in the dorsal side of the yolk syncytial layer (YSL) under the embryonic shield, the zebrafish organizer, until the onset of gastrulation. Furthermore, dharma expressed in the YSL induced the organizer in a non-cell-autonomous manner. These results provided the first identification of a zygotic gene to be implicated in the formation of an organizer-inducing center.