Lead exposure affects levels of galactolipid metabolic enzymes in the developing rat brain

Lead poisoning is known to cause myelin defects. Galactolipids are the major lipid components of myelin and myelin-competent oligodendrocytes. The present study examines the cellular activity of enzymes involved in the galactolipid pathway, tissue concentrations of galactolipids, and the cellular activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) in rat pups exposed to lead in utero and subsequently through maternal milk from exposed mothers and in drinking water following weaning. Pups from control and lead-treated groups (500 or 2000 ppm lead in the drinking water) were euthanized by decapitation on postnatal day 7, 14, 21, 35, or 56. Lead decreased levels of galactolipids and the oligodendrocyte marker CNPase in the brain to a similar degree. The ratios of galactocerebrosides/sulfatides and nonhydroxy fatty acid/hydroxy fatty acid forms of the galactolipids were not altered by lead treatment. In contrast, the activities of the galactolipid metabolic enzymes were reduced to a degree significantly greater than that of CNPase or galactolipids. These results are consistent with previously obtained data indicating that in vitro cultured oligodendroglial progenitor cells are a target for Pb toxicity. Chronic Pb exposure may impact on brain development by impairing timely myelin production due to perturbation of the early developmental commitment of oligodendroglial progenitors. It is further suggested that perturbation of the galactolipid pathway during the developmental maturation of oligodendrocytes may represent a contributing mechanism for Pb-induced neurotoxicity.

The arrest gene is required for germline cyst formation during Drosophila oogenesis

In Drosophila, oogenesis is initiated when a germline stem cell produces a differentiating daughter cell called the cystoblast. The cystoblast undergoes four rounds of synchronous divisions with incomplete cytokinesis to generate a syncytial cyst of 16 interconnected cystocytes, in which one cystocyte differentiates into an oocyte. Strong mutations of the arrest (aret) gene disrupt cyst formation and cause the production of clusters of ill-differentiated germline cells that retain cellular and molecular characteristics of cystoblasts. These mutant germ cells express high levels of BAM-C and SXL proteins in the cytoplasm but do not accumulate markers for advanced cystocytes or differentiating oocytes, such as the nuclear localization of SXL or the accumulation of osk mRNA, orb mRNA, and cytoplasmic dynein. However, the mutant germ cells do not contain spectrosomes, the cytoplasmic structure that objectifies the divisional asymmetry of the cystoblast. The aret mutant germ cells undergo active mitosis with complete cytokinesis. Their mitosis is accompanied by massive necrosis, so that the number of germ cells in a stem cell-derived cluster ranges from one to greater than 70. These defects of aret mutants reveal a novel function of aret as the first gene with a defined function in the cystoblast to cyst transition during early oogenesis.

In vitro differentiation of human marrow stromal cells into early progenitors of neural cells by conditions that increase intracellular cyclic AMP

Human marrow stromal cells (hMSCs) are multipotential stem cells that can be differentiated into bone, cartilage, fat, and muscle. In the experiments here, we found that undifferentiated cultures of hMSCs express some markers characteristic of neural cells such as microtubule-associated protein 1B (MAP1B), neuron-specific tubulin (TuJ-1), neuron-specific enolase (NSE), and vimentin. By treating hMSCs with 0.5 mM isobutylmethylxanthine (IBMX)/1 mM dibutyryl cyclic AMP (dbcAMP) for 6 days, about 25% of the hMSCs differentiated into cells with a typical neural cell morphology and with increased levels of both NSE and vimentin. The data suggested that the hMSCs may have been differentiated into early progenitors of neural cells in vitro under conditions that increase the intracellular level of cAMP.

Asymmetric germ cell division and oocyte determination during Drosophila oogenesis

Early oogenesis in Drosophila, with a stereotypic pattern of germ cell division and differentiation, provides an attractive model for studying cell lineage and patterning. Drosophila oogenesis is initiated when a germline stem cell divides asymmetrically to produce a daughter stem cell and a cytoblast. The cystoblast then undergoes four rounds of incomplete mitoses to form a 16-cell cyst, accompanied by the formation of the fusome. Within the cyst, one of the two cells with four intercellular bridges differentiates into an oocyte while the rest become nurse cells. The oocyte then translocates within the cyst to a posterior position, which defines the anterio-posterior axis of the future embryo. Recent studies have shown that the asymmetric germline stem cell division is controlled by somatic signaling involving piwi, fs(1)Yb, and the dpp pathway as well as by intrinsic mechanisms involving pumilio, nanos, arrest, bag-of-marbles, and the spectrosome-the fusome precursor in the stem cells and the cystoblast. The spectrosome in the cystoblast appears to play an important role in polarized fusome growth during cyst formation. The fusome may guide the formation of a polarized microtubule network for the intracyst transport of certain RNAs and proteins to the cystocyte destined to become the oocyte. Genes such as egalitarian, Bicaudal D, stonewall, and encore are important for oocyte determination, while differential adhesion between the oocyte and its surrounding prefollicle cells, as mediated by armadillo, alpha-catenin, shotgun, and the spindle genes, is crucial for oocyte translocation. Early oogenesis shares many parallel features to early spermatogenesis, although distinct differences are also observed at both the phenomenological and mechanistic levels. The study of oogenesis, progressing at an exciting rate, contributes significantly to our understanding of the mechanisms underlying proliferation, differentiation, and patterning.

[Effective suppression of the infection and pathogenesis of simian immunodeficiency virus in transgenic lymphocytes mediated by self-cleavagble ribozyme]

OBJECTIVE

To obtain transgenic lymphocytes that are resistant to the infection and pathogenesis of simian immunodeficincy virus (SIV).

METHODS

A self-cleaving ribozyme was formed by introducing a fragment of ribozyme target sequence cleft by hammerhead ribozyme to the ribozyme downstream. Self-cleavable ribozyme gene was synthesized, amplified and cloned at the XhoI SalI site of pBluescript SK. The construct bearing 10 copies of ribozyme was obtained through successively cloning four times. The in vitro activity of self-cleavable ribozyme was tested, and then the self-cleaving ribozyme gene was transferred into mammalian expression vector pCI before transfection. The expression vectors harboring self-cleavable ribozyme gene were transfected into lymphocytes with liposome-mediated transfection method. The transfected cell clones were selected in the culturing medium containing 400 mg/L G418. The resistance of transgenic cell to simian immunodeficency virus infection was evaluated by immunofluorescence assays.

RESULTS

more than 85% of decameric ribozyme self-cleaved into monomeric ribozymes after incubation for 15 minutes at 37 degrees C. The number of cleavage products of decameric ribozyme during the first 25 minutes exceeds those of the monomeric ribozyme by 13.31% though the molar mass average of decameric ribozyme is less than 1/10 of that of the monomer ribozyme. The Northern dot blot results demonstrated that the monomer ribozyme gene and the decameric ribozyme gene had been transfected and expressed in the cells. SIV challenge trials showed that after 6 days after inoculation of SIV the cells transfected with the monomer ribozyme gene grew normally, no fused cell was observed; and most of the cells transfected with decameric gene grew well, but a few fused cells were observed; The inhibition rate was 100% for the cells transfected with monomer ribozyme gene to the SIV antigen positive cells, 91.2% for the cells transfected with decameric ribozyme gene, and 48% for the cells transfected with the empty expression vector.

CONCLUSION

The lymphocytes transfected with self-cleavable ribozyme gene make a strong resistance to SIV infection and pathogenesis. The cells transfected with monomeric ribozyme gene show a better inhibiting effect on SIV infection and pathogenesis in comparison with the cells transfected with decameric ribozyme gene.

Up-regulation of Na,K-ATPase beta 1 transcription by hyperoxia is mediated by SP1/SP3 binding

The sodium pump, Na,K-ATPase, is an important protein for maintaining intracellular ion concentration, cellular volume, and ion transport and is regulated both transcriptionally and post-transcriptionally. We previously demonstrated that hyperoxia increased Na,K-ATPase beta(1) gene expression in Madin-Darby canine kidney (MDCK) cells. In this study, we identify a DNA element necessary for up-regulation of the Na,K-ATPase beta(1) transcription by hyperoxia and evaluate the nuclear proteins responsible for this up-regulation. Transient transfection experiments in MDCK cells using sequential 5'-deletions of the rat Na,K-ATPase beta(1) promoter-luciferase fusion gene demonstrated promoter activation by hyperoxia between -102 and +151. The hyperoxia response was localized to a 7-base pair region between -62 and -55, which contained a GC-rich region consistent with a consensus sequence for the SP1 family, that was sufficient for up-regulation by hyperoxia. This GC element exhibited both basal and hyperoxia-induced promoter activity and bound both transcription factors SP1 and SP3 in electrophoretic mobility shift assays. In addition, electrophoretic mobility shift assays demonstrated increased binding of SP1/SP3 in cells exposed to hyperoxia while mutation of this element eliminated protein binding. Other GC sites within the proximal promoter also demonstrated up-regulation of transcription by hyperoxia, however, the site at -55 had higher affinity for SP proteins.

A comparative study on potential cytogenetic fingerprints for radiation LET in human lymphocytes

PURPOSE

To carry out a comparative study on potential cytogenetic fingerprints for radiation LET in human metaphase lymphocytes.

MATERIALS AND METHOD

Human lymphocytes were irradiated in vitro with 3.0 Gy 60Co gamma-rays, 0.9 Gy 3H beta-rays or 0.2 Gy 2.7 Mev neutrons. Detailed chromosome aberrations were analysed by combined FISH with pan-telomere staining and specific whole-chromosome painting (1, 2 and 4). Total chromosome translocations and insertions were also analysed by multicolour whole-chromosome painting (chromosomes 1, 2 and 4 orange, chromosomes 3, 5 and 6 green).

RESULTS

Among the six proposed radiation cytogenetic fingerprints, the ratio of total simple translocations to insertions (I-ratio), showed the largest difference between low-LET 60Co gamma-ray and high-LET neutron radiation. The ratios of complete exchanges to incomplete rejoinings [S(I)-ratio] and dicentrics to interstitial deletions (H-ratio), showed a similar significant difference between low- and high-LET radiation. The ratios of centric rings to interstitial deletion (G-ratio) showed a trend of LET-related difference, but the difference was not significant in this data set. The ratios of dicentrics to centric rings (F-ratio) and apparent complete exchanges to hidden complete exchanges [S(II)-ratio], showed no difference between low- and high-LET radiation. In the 1426 radiation-induced chromosome aberrations observed after 52 h culture, evidence for sister-chromatid fusion but not telomere addition was found.

CONCLUSION

Pan-telomere staining plus specific whole chromosome painting allows simultaneous and objective detection of complete or incomplete chromosome exchanges and interstitial or terminal deletions in human peripheral lymphocytes. Of the six proposed cytogenetic ratios, the I-ratio is the most effective cytogenetic fingerprint for distinguishing low-LET from high-LET radiation in human metaphase human lymphocytes.

[cDNA cloning and sequence analysis of the seventh segment of maize rough dwarf virus genome]

The double strand RNA of maize rough dwarf virus (MRDV) was prepared from the maize samples showing symptoms which was from the Luanchen county of Heibei province of China. The primers were designed according to the known sequence of MRDV, the cDNA sequence of the seventh segment of MRDV was obtained by RT-PCR, the S7 sequence was analyzed by computer after sequencing. The results showed: the full length of the S7 cDNA is 1936 bp and equal to that of the S7 cDNA from abroad, the two open reading frame(ORF1 and ORF2) contained in the S7 segment are also unchanged. In comparison with the S7 segment from Italy, the homology of S7 nucleotide is 87.7% and the homology of ORF1 amino acid sequence is 91.6%. However, the MRDV S7 segment and the rice black strike dwarf virus S8 segment showed 95.5% nucleotide identities and 93.5% ORF1 amino acid identities.

Influence of cellular ganglioside depletion on tumor formation

BACKGROUND

Gangliosides are immunosuppressive cell surface molecules that are often present in high concentrations in and shed actively by tumor cells. These molecules inhibit the antitumor immune response that is implicated in tumor rejection. We therefore determined the ability of tumor cells pharmacologically depleted of gangliosides to form tumors in mice.

METHODS

We tested a ganglioside-rich subline of B16 murine melanoma, MEB4, and MEB4 cells that had been depleted of endogenous gangliosides by incubation with 0.5 microM 1-phenyl-2-hexadecanoylamino-3-pyrrolidino-1-propanol, a specific inhibitor of the enzyme glucosylceramide synthase. Tumor formation was assessed twice a week for 10 weeks after the intradermal injection of tumor cells, and metastatic potential was assessed 4 weeks after tail vein injection of tumor cells. All P values are from two-sided tests.

RESULTS

Reduction of the ganglioside content of MEB4 cells, which was not cytotoxic to cells and did not inhibit cell proliferation in vitro, markedly reduced their ability to form tumors. Only 40% of the mice given an intradermal injection of 10(5) ganglioside-depleted MEB4 cells developed tumors compared with 100% of the mice given an injection of 10(5) control MEB4 cells (P<.001). Ganglioside depletion also reduced metastasis: A mean of five pulmonary metastases was detected per mouse given an injection of 2 x 10(5) ganglioside-depleted MEB4 cells compared with a mean of 25 per mouse given an injection of 2 x 10(5) control MEB4 cells.

CONCLUSION

Tumor cells with a pharmacologically decreased concentration of gangliosides produce fewer tumors in mice than do untreated cells, suggesting that pharmacologic depletion of gangliosides should be explored further as a therapeutic approach to cancer.

The interaction of lead exposure and arylsulfatase A genotype affects sulfatide catabolism in human fibroblasts

Lead exposure causes cognitive and behavioral deficits in some affected children. We propose that a contributing mechanism for the neurological damage is that lead induces critically low levels of arylsulfatase A (ASA) at sensitive stages of nervous system development. It is hypothesized that the combined effects of a single nucleotide polymorphism (SNP) in human ASA which results in reduced levels of the enzyme, and lead concentrations which decrease ASA activity culminate in cellular enzymic activity that is below a critical threshold required for the maintenance of normal nervous system function. Human fibroblasts grown in the presence of 20 microM lead acetate exhibit a more than 60% decrease of cellular ASA enzyme protein. Lead treatment of cells from individuals with the SNP(s) of pseudodeficient ASA, but not those from subjects with the normal gene, results in a significant decrease in ability of the cells to desulfate sulfatide, the substrate of ASA. The decrease in the degree of sulfatide catabolism is consistent with possible enhanced lead-induced neurobehavioral effects in individuals homozygous for the pseudodeficiency polymorphism(s) of ASA.

A novel alpha-helix-liked metallohelicate series and their structural adjustments for the isomorphous substitution

A novel metallohelical motif is well designed and synthesized by mimicking the alpha-helical fold structure of protein. The 1D helical structures of [Cd(CH2(COO)2)(SC(NH2)2)2]n (I) and [Zn(CH2(COO)2) (SC(NH2)2)2]n (II) are primarily induced and stabilized by the multiple long-range intrahelix hydrogen bonds. Malonate dianion acts as a bidentate ligand coordinated with metal ions to form the backbone of the helix, and thiourea molecules that bend into the helical turn are involved in the intrahelix hydrogen-bond system. The metal ion occupations in the helix of I and II can be freely substituted by simply controlling the initial ratio of those two metal ions. Single crystals of three mixed metal ion complexes of [Cd0.77Zn0.23(CH2(COO)2)(SC(NH2)2)2]n (III), [Cd0.50Zn0.50(CH2(COO)2)(SC(NH2)2)2]n (IV), and [Cd0.21Zn0.79(CH2(COO)2)(SC(NH2)2)2]n (V) were synthesized from systems with an initial Cd/Zn mole ratio of 1:1 for III, 1:2 for IV, and 1:8 for V. They are isomorphous as confirmed by X-ray characterization. When the metal ion is substituted, the multiple intrahelix hydrogen interaction motifs of the coordination polymer structure are self-adjusted to sustain their 1D helical motifs.

[Effect of jiaweiyiguanjian decoction on hypothalamus-pituitary-thyroid gland (HPT) in rat model with Yin-deficiency of liver and kidney induced by slow irritation]

OBJECTIVE

To explore the mechanism of Jiaweiyiguanjian decoction in nourishing the liver and kidney.

METHOD

A rat model with Yin-deficiency of liver and kidney was made by way of slow irritation. Thyrotropin-releasing-hormone(TRH) of thyron and blood, TSH of pituitary and blood, thyroxine, 3,5,3',5-tetraiodothyronine(FT4) and 3,3',5-traiodothyronine(FT4), 3,3',5-traiodothyronine(rT3) were used as indexes to study the effect of the decoction on HPT.

RESULT

The TRH Secretion from hypothalamus increased (P < 0.05), TSH of pituitary and blood reduced(P < 0.05), FT3 and FT4 of blood decreased at the same time and rT3 of blood, increased. The indexes of the treatment group were found almost the same as the those of the normal control group.

CONCLUSION

Jiaweiyiguanjian Decoction could adjust HPT.

Enteropathogenic Escherichia coli (EPEC) attachment to epithelial cells: exploiting the host cell cytoskeleton from the outside

Enteropathogenic Escherichia coli (EPEC), a leading cause of human infantile diarrhoea, is the prototype for a family of intestinal bacterial pathogens that induce attaching and effacing (A/E) lesions on host cells. A/E lesions are characterized by localized effacement of the brush border of enterocytes, intimate bacterial attachment and pedestal formation beneath the adherent bacteria. As a result of some recent breakthrough discoveries, EPEC has now emerged as a fascinating paradigm for the study of host-pathogen interactions and cytoskeletal rearrangements that occur at the host cell membrane. EPEC uses a type III secretion machinery to attach to epithelial cells, translocating its own receptor for intimate attachment, Tir, into the host cell, which then binds to intimin on the bacterial surface. Studies of EPEC-induced cytoskeletal rearrangements have begun to provide clues as to the mechanisms used by this pathogen to subvert the host cell cytoskeleton and signalling pathways. These findings have unravelled new ways by which pathogenic bacteria exploit host processes from the cell surface and have shed new light on how EPEC might cause diarrhoea.

[Quality control of plasma(serum) specimen for the detection of HCV RNA with PCR]

OBJECTIVE

To define the optimal collection and storage parameters of serum (plasma) for HCV RNA detection.

METHODS

The serum(plasma) obtained from HCV RNA positive patients by different means and different processing and storage conditions, then HCV RNA was detected with the fluorescent quantitative PCR.

RESULTS

The centrifugation was performed within 2 hours after formation of the clot, loss of HCV RNA titers was 10.42% and significant loss of HCV RNA titers 40.49% was observed after 4 h. The HCV RNA titers in plasma samples with anticoagulants were much higher than that in serum samples(citrate sodium-anticoagulized 40.97%, EDTA-anticoagulated 53.14%). There was no loss of HCV RNA with up to three freeze-thaw cycles. A significant decrease in HCV RNA(15.6%) was observed at -20 degrees C after one year.

CONCLUSIONS

The results suggested that it is important to process and store clinical samples for HCV RNA detection. The EDTA-K2 as anticoagulants the plasma must be collected within 3 h, and the serum must be prepared within 2 hours after hemosposia. It is essential to store the sample under -70 degrees C for the stability of HCV RNA in a longer time.

Small-angle measurement based on surface-plasmon resonance and the use of magneto-optical modulation

A new, to our knowledge, optical method for small-angle measurement based on surface-plasmon resonance (SPR) is presented. In this method the high sensitivity of the phase of SPR to the angle of incidence is employed to improve the resolution of the measurement of the angle. Small-angle measurement is performed by the monitoring of the phase shift resulting from the minute change of the angle of incidence with the use of magneto-optical modulation. The validity of this method is demonstrated, and a measurement resolution of 0.2 arc sec is achieved experimentally.

A targeted gene silencing technique shows that Drosophila myosin VI is required for egg chamber and imaginal disc morphogenesis

We report that Drosophila unconventional myosin VI, encoded by Myosin heavy chain at 95F (Mhc95F), is required for both imaginal disc and egg chamber morphogenesis. During oogenesis, Mhc95F is expressed in migrating follicle cells, including the border cells, which migrate between the nurse cells to lie at the anterior of the oocyte; the columnar cells that migrate over the oocyte; the centripetal cells that migrate between the oocyte and nurse cells; and the dorsal-anterior follicle cells, which migrate to secrete the chorionic appendages. Its function during development has been studied using a targeted gene silencing technique, combining the Gal4-UAS targeted expression system and the antisense RNA technique. Antibody staining shows that the expression of myosin 95F is greatly decreased in follicle cells when antisense Mhc95F RNA is expressed. Interfering with expression of Drosophila myosin VI at various developmental stages frequently results in lethality. During metamorphosis it results in adult flies with malformed legs and wings, indicating that myosin VI is essential for imaginal disc morphogenesis. During oogenesis, abnormal follicle cell shapes and aberrant follicle cell migrations are observed when antisense Mhc95F is expressed in follicle cells during stages 9 to 10, suggesting that the Drosophila myosin VI is required for follicle cell epithelial morphogenesis.

Combined FISH with pan-telomeric PNA and whole chromosome-specific DNA probes to detect complete and incomplete chromosomal exchanges in human lymphocytes

PURPOSE

To combine FISH with pan-telomeric peptide nucleic acid (PNA) and whole chromosome-specific DNA probes to detect complete and incomplete chromosome exchanges in human lymphocytes.

MATERIALS AND METHODS

Human lymphocytes were irradiated in vitro with 0.9 Gy low dose-rate (0.019 Gy/h) tritium beta-rays. Metaphase spreads were treated with RNase, fixed in 1:3 acetic acid:methanol, and then further treated with KCl, proteinase K and fixed in 4% paraformaldehyde. Slides were denatured, hybridized for 1.5 h with an FITC-labelled telomeric PNA probe, and rehybridized overnight with a spectrum-orange whole-chromosome probe specific for chromosomes 1, 2 and 4. Hybridized spreads were washed with 70% formamide/20 x SSC and counterstained with DAPI.

RESULTS

All three pairs of labelled chromosomes together with 92 telomeres were readily visible after hybridization. The whole chromosomes 1, 2 and 4 were painted orange, and all telomeres were stained green. Unpainted chromosomes were counterstained blue. In the observed 680 chromosome aberrations induced by tritium beta-rays in human lymphocytes after 52 h of culture, no evidence of telomere addition was detected. Incomplete and hidden complete exchanges and terminal deletions were definitively discriminated.

CONCLUSION

The simultaneous detection of telomeres and specific whole chromosomes allows for the first time accurate analysis of complete and incomplete chromosome exchanges involving painted chromosomes in human lymphocytes.

Background ionizing radiation plays a minor role in the production of chromosome translocations in a control population

PURPOSE

To obtain a relationship between background chromosome translocation frequency and age with translocation frequency measured to a high statistical precision, and to identify the role of background ionizing radiation in the production of chromosome translocations in a control population.

MATERIALS AND METHODS

Lymphocytes from 35 healthy control individuals (15 females and 20 males) were scored, using fluorescence in situ hybridization, for the presence of chromosomal translocations. Translocation frequencies were measured to a high statistical precision (s.d. 25% or less for each individual). These control subjects were of varying ages, ranging from 0 (cord blood) to 98 years.

RESULTS

In a total of 521,492 metaphases (203,754 genome equivalent cells) scored, an average of 5,822 genome equivalent cells per individual, 764 translocations were observed in the 35 individuals. The translocation frequencies ranged from 0 (for cord blood) to 0.0167 (for a 98 year old) translocations per cell. The average age and translocation frequency was 50 years and 0.004 translocations per cell, respectively. The best fit of the relationship between translocations and age was: Y=7x10(-4)+6.9x10(-6)A+1.35x10(-6)A2, which does not obey the linear relationship expected from chronic background radiation alone. The curvilinear relationship observed clearly shows that other endogenous and exogenous clastogens or clastogenic events, in addition to radiation, serve to generate chromosome translocations in control populations.

CONCLUSION

The background translocation frequency in control individuals follows a curvilinear relationship with age. No significant variation was observed between individuals of the same age. Clastogenic processes of normal aging and physiological factors in additional to ionizing radiation play a major role in the production of chromosome translocations in a control population. Background radiation, however, appears to play a minor role in chromosome translocation production in control individuals living near sea level.

Exposure temperature, but not donor age, is a confounding factor for in vitro translocation production by chronic irradiation

PURPOSE

To assess the effects of incubation temperature during irradiation, and of donor age, on the in vitro induction of chromosomal translocations in human lymphocytes.

MATERIAL AND METHODS

Lymphocytes from six human male donors were scored, using fluorescence in situ hybridization, for the presence of chromosomal translocations involving chromosomes 1 to 6 after in vitro, chronic exposure (delivered continuously over 48 h at 37 degrees C or at 20 degrees C) to tritium beta-rays or 60Co gamma-rays.

RESULTS

No age-related difference in the alpha coefficients of the fitted induction curves was observed for gamma-ray-exposed lymphocytes obtained from four donors whose ages ranged from 24 to 79 years, or for tritium beta-ray-exposed lymphocytes from two donors aged 36 and 62 years. Duplicate samples from one donor, irradiated concurrently at 20 degrees C or 37 degrees C, gave significantly different alpha coefficients: 0.128+/-0.008 and 0.053+/-0.004, respectively (p<0.0001). The S-ratio (the ratio of induced complete to incomplete translocations) was found to be independent of radiation dose, donor age and exposure temperature.

CONCLUSIONS

For biodosimetry in chronic irradiation situations, the use of alpha coefficients derived from the dose-response curves of cells chronically irradiated in vitro at body temperature is recommended. With respect to induction rates, donor age does not appear to be a confounding factor. The S-ratio is independent of radiation doses, exposure temperatures, or donor ages.

Alpha coefficient of dose-response for chromosome translocations measured by FISH in human lymphocytes exposed to chronic 60Co gamma rays at body temperature

PURPOSE

To measure the alpha coefficient, the initial slope of the translocation dose-response curve, for 60Co gamma-rays in human lymphocytes.

MATERIALS AND METHODS

Human lymphocytes were exposed to 0, 0.32, 0.62 and 0.92 Gy of chronic 60Co gamma-rays under conditions that reduce the metabolic stress to the cells. Chromosome translocation frequencies were measured using fluorescence in situ hybridization with a whole-chromosome probe cocktail specific for chromosomes 1, 2, 4 (orange) and 3, 5, 6 (green).

RESULTS

A total of 72,383 metaphases were analysed (33,429 in exposed cells) in two individuals. The shape of the dose-response curves for translocations was linear, and alpha coefficient was measured as 0.024 +/- 0.002 translocations per cell per Gy for the combined data for two 24 year old male donors.

CONCLUSION

The alpha coefficients measured after chronic exposure were in good agreement with that reported in the literature for acute, low-dose exposure of human lymphocytes to 60Co gamma-rays.

[A pharmacognostical study on herba Spirodelae and its adulterants]

OBJECTIVE

To Study the characteristics of Herba Spirodelae(Spirodela polyrrhiza) and its adulterants S. oligorrhiza and Lemna minor for identification.

METHOD

The characteristics were compared and identified morphologically and histologically.

RESULT

The morphological and histological characteristics of S. polyrrhiza, S. oligorrhiza and L. minor are different from each other. Several tables, keys and drawings are given.

CONCLUSION

The main macroscopical and microscopical characteristics can be used fo differentiate S. polyrrhiza from its adultrants.

VirE1 is a specific molecular chaperone for the exported single-stranded-DNA-binding protein VirE2 in Agrobacterium

Agrobacterium tumefaciens induces tumours on plants by transferring a nucleoprotein complex, the T-complex, from the bacterium to the plant cell. The T-complex consists of a single-stranded DNA (ssDNA) segment, the T-DNA, and VirD2, an endonuclease covalently attached to the 5' end of the T-DNA. A type IV secretion system encoded by the virB operon and virD4 is required for the entry of the T-complex and VirE2, a ssDNA-binding protein, into plant cells. The VirE1 protein is specifically required for the export of the VirE2 protein, as demonstrated by extracellular complementation and tumour formation. In this report, using a yeast two-hybrid system, we demonstrated that the VirE1 and VirE2 proteins interact and confirmed this interaction by in vitro binding assays. Although VirE2 is a ssDNA-binding protein, addition of ssDNA into the binding buffer did not interfere with the interaction of VirE1 and VirE2. VirE2 also interacts with itself, but the interaction between VirE1 and VirE2 is stronger than the VirE2 self-interaction, as measured in a lacZ reporter gene assay. In addition, the interaction of VirE2 with itself is inhibited by VirE1, indicating that VirE2 binds VirE1 preferentially. Analysis of various virE2 deletions indicated that the VirE1 interaction domain of VirE2 overlaps the VirE2 self-interaction domain. Incubation of extracts from Escherichia coli overexpressing His-VirE1 with the extracts of E. coli overexpressing His-VirE2 increased the yield of His-VirE2 in the soluble fraction. In a similar purified protein solubility assay, His-VirE1 increased the amount of His-VirE2 partitioning into the soluble fraction. In Agrobacterium, VirE2 was undetectable in the soluble protein fraction unless VirE1 was co-expressed. When urea was added to solubilize any large protein aggregates, a low level of VirE2 was detected. These results indicate that VirE1 prevents VirE2 from aggregating, enhances the stability of VirE2 and, perhaps, maintains VirE2 in an export-competent state. Analysis of the deduced amino acid sequence of the VirE1 protein revealed that the VirE1 protein shares a number of properties with molecular chaperones that are involved in the transport of specific proteins into animal and plant cells using type III secretion systems. We suggest that VirE1 functions as a specific molecular chaperone for VirE2, the first such chaperone linked to the presumed type IV secretion system.

Influence of 5-bromodeoxycytosine substitution on triplex DNA stability and conformation

Three triple-helical hairpin DNAs with substitution of 5-bromocytosine for cytosine in different strands have been investigated by molecular mechanics and Raman spectroscopy. The stability of the three substituted triplexes were compared with the corresponding unsubstituted triplex DNA by the molecular mechanics method. Base stacking interactions and strand--strand interactions of each triplex were analyzed in detail. Sugar conformations in these triplexes have been determined by both vibrational spectroscopy and molecular dynamics simulation. The hairpin triplexes with substitution occurring in strand I or both in strands I and III have the main sugar conformation of C3'-endo, while the triplex with substitution occurring in strand III is the combination of C3'-endo and C2'-endo sugar conformation. Theoretical results are basically in agreement with experiments.

Theoretical and experimental tests of a chromosomal fingerprint for densely ionizing radiation based on F ratios calculated from stable and unstable chromosome aberrations

In the present study, F ratios for both stable chromosome aberrations, i.e. ratios of translocations to pericentric inversions, and unstable aberrations, i.e. dicentrics and centric rings, were measured using fluorescence in situ hybridization. F ratios for stable aberrations measured after exposure to low (2.89 Gy 60Co gamma rays) and high-LET (0.25 Gy 56Fe ions; 1.25 Gy 56Fe ions; 3.0 Gy 12C ions) radiation were 6.5 +/- 1.5, 4.7 +/- 1.6, 9.3 +/- 2.5 and 10.4 +/- 3.0, respectively. F ratios for unstable aberrations measured after low (2.89 Gy 60Co gamma rays) and high-LET (0.25 Gy 56Fe ions; 3.0 Gy 12C ions) radiations were 6.5 +/- 1.6, 6.3 +/- 2.3 and 11.1 +/- 3.7, respectively. No significant difference between the F ratios for low- and high-LET radiation was found. Further tests on the models for calculation of the F ratio proposed by Brenner and Sachs (Radiat. Res. 140, 134-142, 1994) showed that the F ratio may not be straightforward as a practical fingerprint for densely ionizing radiation.

Biological dosimetry of beta-ray exposure from tritium using chromosome translocations in human lymphocytes analyzed by fluorescence in situ hybridization

Radiation exposures from tritium make up a substantial fraction of the occupational and accidental radiation exposures associated with the nuclear power industry. Tritiated water, the most abundant form of tritium, is of particular interest because it is readily taken up by human cells and its irradiation of the cells is spread over a period of days. To approximate the prolonged exposure and the conditions that the cells of an individual would experience in vivo, we irradiated human lymphocytes with tritiated water for 48 h in a 1:1 blood:medium mix. For estimation of the tritium beta-ray dose, a cellular water content of 0.78, based on measurements of human lymphoblastoid cells in culture medium, was used. A modified dose calculation formula was developed for the radiation exposure conditions. A total of 48,014 metaphases (14,482 in irradiated samples and 33,532 in control, unirradiated samples) in human lymphocytes cultured for 72 h after exposure were analyzed for chromosome translocations using fluorescence in situ hybridization. The linear slope (alpha coefficient) of the dose-response curve was measured to be (3.93+/-0.42) x 10(-2) and (5.26+/-0.48) x 10(-2) translocations per cell per gray for complete translocations (tc) and complete translocations plus incomplete translocations [ti(Ab)], respectively, when the data were fitted to a linear model using a weighted least-squares method. The alpha coefficient for tc is significantly lower than that for conventionally measured dicentrics after tritium beta irradiation, but the alpha coefficient for tc + ti(Ab) does not differ significantly from that for dicentrics. This is in agreement with theoretical considerations. The importance of scoring criteria is stressed. The frequency of tc + ti(Ab) is proposed to be a reliable biodosimeter for tritium exposures, and its practical use in a dose reconstruction is presented.

[Multicentre, randomized, prospective and comparative study of ceftriaxone, cefotaxime and cefuroxime in treating mild to moderate respiratory tract infection]

OBJECTIVE

The objective of this multicentre, randomized, prospective and comparative study was to evaluate and compare the efficacy and safety of 1 g intravenous ceftriaxone (active ingredient of Rocephin), 3 g intravenous cefoiaxime (active ingredient of clafron), and 2.25 g intavenous cefuroxime (active ingredient of Zinacef).

METHOD

In this multicentre, randomized, prospective and comparative study, patients received 1 g of ceftriaxone intravenously once a day (group A), or 1 g of cefotaxime intravenously three times a day (group B), or 0.75 g of cefuroxime intravenously three time a day (group C). 197 patients were enrolled in the study, and in 142 (48 in group A, 46 in group B and 48 in group C) we were able to make an evaluation.

RESULT

The overall efficacy (bacteriological eradication plus clinical cure or clear improvement) of ceftriaxone, cefotaxime and cefuroxime were 81%, 83%, 79% respectively (P > 0.05). The eradication rate for three groups were 80%, 78%, 75% (P > 0.05). No adverse events occured.

CONCLUSION

Data obtained in our study indicate that for the majority of patients with lower respiratory tract infections, 1 g ceftriaxone, 3 g cefotaxime and 2.25 g cefuroxime are effective and safe, and 7 days therapy is enough, but the use of 1 g ceftriaxone is more convenient.

[Clinical analysis of syndrome of obstructive sleep apnea (OSA) induced acute respiratory failure]

OBJECTIVE

To study the clinical characteristics of syndrome of OSA induced acute respiratory failure that might allow earlier recognition and treatment in critical care.

METHOD

The clinical and laboratory characteristics of 9 patients were reviewed.

RESULT

9 patients (8 female, 1 male) presented with obesity and mental disturbance, with a BMI being 44.97 kg/m2, (45.25 kg/m2 in the female). The mean age of the group was 67.89 years (61-74 y). All had respiratory acidosis (mean pH 7.1732), hypercapnia (mean PaCO2 12.56 kPa) (8.53-19.09 kPa), and hypoxemia (mean PaO2 5.20 kPa) (3.87-5.87 kPa). During period of clinical stability all but 2 had awake hypercapnia (mean PaCO2 6.23 kPa) (5.10-7.29 kPa). Four of the 9 patients had pulmonary function test showing FEV1% > 70%.

CONCLUSION

OSAS induced acute respiratroy failure has a sudden onset and various presentation and can be reversed with early and proper treatment. The severity of abnormal pulmonary function was less than what would be expected to cause respiratroy failure.

[Comparison of continuous positive airway pressure (CPAP) with uvulopalatopharyngoplasty in the treatment of obstructive sleep apnea syndrome]

OBJECTIVE

To compare the efficacy, side effects, and effects on parameters of sleep of continuous positive airway pressure (CPAP) and uvulopalatopharyngoplasty (UPPP) therapy in OSAS and evaluate their role in the treatment of OSAS.

METHOD

60 patients with OSAS were studied, 36 patients treated with CPAP, 24 patients with UPPP, and the parameters of polysomnography (PSG) obtained before and after treatment were analysed.

RESULT

Respiratory disturbance index and sleep hypoxemia were improved significantly in both groups, but the CPAP group was better than UPPP group (P < 0.01). The efficacy was 97% in CPAP and 46% in UPPP group (P < 0.01). The longest apnea duration shortened in CPAP group (from 89 +/- 46 to 39 +/- 19) but there was no difference in UPPP (from 76 +/- 26 to 62 +/- 30) group. The apnea duration in 10 patients was lengthened.

CONCLUSION

The effects of UPPP in OSAS were limited. CPAP was more effective than UPPP. CPAP may be indicated as the first choice in the treatment of OSAS.

Limiting dilution analysis of peripheral blood lymphocytes reacting with non-small-cell lung cancer: functionally heterogeneous effectors efficiently lyse autologous cancer cells

It has recently been shown that the infusion of tumor infiltrating lymphocytes (TIL) and recombinant interleukin-2 (rIL-2) in patients operated on for advanced non-small-cell lung cancer (NSCLC), has significant effects in terms of the survival time and control of local relapses. Despite the evident clinical effects, the treatment is unavailable for patients in which TIL have lost their proliferative potential. In an attempt to identify new sources of effector cells using mixed lymphocyte/tumor cultures (MLTC), populations of peripheral blood (PB) lymphoid cells, which have the capability of lysing autologous NSCLC, were studied at the clonal level. Specific cytolytic lymphocytes were detected at very low frequencies in two out of four patients, whereas non-MHC restricted cytolytic T cells were frequently detected. Cytolytic CD4+ belonged to the Th0 or Th2 subsets and were characterized by cytokine secretion patterns suggestive of a lymphokine cascade that could be involved in cancer control. The identification of different efficient effector mechanisms at the clonal level strongly supports the use of in vitro activated lymphocytes, derived from PB, in protocols of adoptive immunotherapy in patients with advanced NSCLC in which TIL are unavailable.

Agrobacterium VirD2 protein interacts with plant host cyclophilins

Agrobacterium tumefaciens induces crown gall tumors on plants by transferring a nucleoprotein complex, the T-complex, from the bacterium to the plant cell. The T-complex consists of T-DNA, a single-stranded DNA segment of the tumor-inducing plasmid, VirD2, an endonuclease covalently bound to the 5' end of the T-DNA, and perhaps VirE2, a single-stranded DNA binding protein. The yeast two-hybrid system was used to screen for proteins interacting with VirD2 and VirE2 to identify components in Arabidopsis thaliana that interact with the T-complex. Three VirD2- and two VirE2-interacting proteins were identified. Here we characterize the interactions of VirD2 with two isoforms of Arabidopsis cyclophilins identified by using this analysis. The VirD2 domain interacting with the cyclophilins is distinct from the endonuclease, omega, and the nuclear localization signal domains. The VirD2-cyclophilin interaction is disrupted in vitro by cyclosporin A, which also inhibits Agrobacterium-mediated transformation of Arabidopsis and tobacco. These data strongly suggest that host cyclophilins play a role in T-DNA transfer.

Effect of selective substitution of 5-bromocytosine on conformation of DNA triple helices

Three triplex DNAs containing 5-bromocytosine[BrC] were studied by vibrational spectroscopy and molecular modelling. Firstly, three oligodeoxypyrimidines of 5'-(TC)3-T4-(BrCT)3 [CBrC], 5'-(TBrC)3-T4-(CT)3 [BrCC] and 5'-(TBrC)3-T4-(BrCT)3 [BrCBrC] were synthesized and then reacted with an oligodeoxypurine of 5'-(AG)3 at pH=4.5 in phosphate buffer respectively to form three comparative hairpin triplex named CY,YC and YY. The results of FT-Raman and IR revealed that YY is almost in A-like form, CY and YC are combinations of A-like form and B-like form, but A-form dominates in CY while B-form is equivalent as A-form in YC. The result is consistent with the theoretical analysis.

[Corneal topography analysis after excimer laser photorefractive keratectomy]

OBJECTIVE

To study the pattern of ablation, evaluate centration and stability following excimer laser photorefractive keratectomy (PRK) for myopia.

METHOD

Corneal topography of 312 patients (366 eyes) with a month, 3 months and 6 months of follow-up after PRK was examined.

RESULTS

The mean decentration from the pupillary center to ablating center was 0.266 mm. In both eyes, the mean decentration was located supernasally. At one month postoperative examination, uniform ablation was 49.5%, semicircular, keyhole, kidney and dumbbell shaped ablations were 42.9% and central island one was 6.0%. Central island pattern affected the best corrected visual acuity greatly. High myopia began regression at 1-3 months after PRK.

CONCLUSION

Corneal topography is essential for evaluating surface changes after PRK. Long-time stability issues are answered with continued topographic follow-up.

Biphasic transitions of a hairpin hexanucleotide triplex DNA

The conformational transitions (helix-coil transitions) of three hairpin triple helices, models 5'-(A-G)(3) + 5'-(T-C)(3)-T(4)-((br)C-T)(3) [CY], 5'-(A-G)(3) + 5'-(T-(br)C)(3)-T(4)-(C-T)(3) [YC] and 5'-(A-G)(3) + 5'-(T-(br)C)(3)-T(4)-((br)C-T)(3) [YY], are characterized in this work by UV spectroscopy. Melting of these triplexes is biphasic, and the profiles are used to obtain the thermodynamic parameters. The thermodynamic properties of the hairpin triplex are T(m) = 19.45 degrees C and DeltaH(vH) = 293.12 kJ mol(-1) for CY, T(m) = 22.85 degrees C and DeltaH(vH) = 256.63 kJ mol(-1) for YC and T(m) = 28.47 degrees C and DeltaH(vH) = 234.68 kJ mol(-1) for YY at pH 4.4. Those of the duplex are T(m) = 30.50 degrees C and DeltaH(vH) = 427.09 kJ mol(-1) for CY, T(m) = 32.96 degrees C and DeltaH(vH) = 374.47 kJ mol(-1) for YC and T(m) = 33.24 degrees C and DeltaH(vH) = 329.67 kJ mol(-1) for YY at pH 4.4. The distinct transitions of triplex to duplex and duplex to single strands are analyzed using the nearest-neighbor Ising model. Electrostatic effects on each conformation are also analyzed.

Spectrosomes and fusomes anchor mitotic spindles during asymmetric germ cell divisions and facilitate the formation of a polarized microtubule array for oocyte specification in Drosophila

In the Drosophila ovary, membrane skeletal proteins such as the adducin-like Hts protein(s), spectrin, and ankyrin are found in the spectrosome, an organelle in germline stem cells (GSC) and their differentiated daughter cells (cystoblasts). These proteins are also components of the fusome, a cytoplasmic structure that spans the cystoblast's progeny that develop to form a germline cyst consisting of 15 nurse cells and an oocyte. Spectrosomes and fusomes are associated with one pole of spindles during mitosis and are implicated in cyst formation and oocyte differentiation. Here we show that the asymmetric behavior of the spectrosome persists throughout the cell cycle of GSC. Eliminating the spectrosome by the htsl mutation leads to randomized spindle orientation, suggesting that the spectrosome anchors the spindle to ensure the asymmetry of GSC division; eliminating the fusome in developing cysts results in defective spindles and randomized spindle orientation as well as asynchronous and reduced cystocyte divisions. These observations suggest that fusomes are required for the proper formation and asymmetric orientation of mitotic spindles. Moreover, they reinforce the notion that fusomes are required for the four synchronous divisions of the cystoblast leading to cyst formation. In htsl cysts which lack fusomes and fail to incorporate a hts gene product(s) into ring canals following cyst formation, polarized microtubule networks do not form, the dynamics of cytoplasmic dynein is disrupted, and oskar and orb RNAs fail to be transported to the future oocyte. These observations support the proposed role of fusomes and ring canals in organizing a polarized microtubule-based transport system for RNA localization that leads to oocyte differentiation.

[The development and clinical application of an easily carried Chinese electrocardiographic auto-diagnostic apparatus]

The 8090 single chip has been used as main core to complete the automatic process, such as controlling electrocardiographer, collecting information, measuring parameters, analysis, diagnosis, and printing Chinese report.

Radioactivity in zircon and building tiles

Zircon (ZrSiO4) is commonly used in the manufacture of glazed tiles. In this study we found high concentrations of the radionuclides 226Ra, 232Th, 40K in zircon sand. The average radium equivalent (A(Ra) + 1.26 A(Th) + 0.086 A(k)) in zircon sand is 17,500 Bq kg(-1), which is 106 times as much as that in ordinary building materials. The external radiation (gamma + beta) dose rates in air at 5 cm from the surface of piles of zircon sand sacks range from 1.1 to 4.9 x 10(-2) mGy h(-1) with an average of 2.1 x 10(-2) mGy h(-1). Although no elevated gamma-ray radiation or radon exhalation rate was detected in rooms decorated with glazed tiles, which is characteristic of combined alpha, beta and gamma emitting thin materials, the average gamma-ray radiation dose rate at the surface of the tile stacks in shops is 1.5 times as much as the indoor background level. The average area density of total beta emitting radionuclides in glazed floor tiles and glazed wall tiles is 0.30 Bq cm(-2) and 0.28 Bq cm(-2), respectively. It was estimated that the average beta dose rates in tissue at a depth 7 mg cm(-2) with a distance 20-100 cm from the floor tiles were 3.2 to 0.9 x 10(-7) Gy h(-1). The study indicates that the beta-rays from glazed tiles might be one of the main factors leading to an increase in ionizing radiation received by the general public. Workers in glazed tile manufacturing factories and in tile shops or stores may be exposed to elevated levels of both beta-rays and gamma-rays from zircon sand or glazed tile stacks. No elevated radiation from unglazed tiles was detected.

Effect of dl-3-n-butylphthalide on brain edema in rats subjected to focal cerebral ischemia

The present study evaluated the effect of dl-3-n-butylphthalide(NBP), a novel brain protective agent, on brain edema in rats following focal ischemia. Edema was induced by occluding the right middle cerebral artery (MCAO), producing permanent focal ischemia in the right cerebral hemisphere, which developed ipsilateral brain edema reproducibly. Edema was assessed 24 h after MCA occlusion by determining the brain water content from wet and dry weight measurements, and the sodium, potassium concentrations with ion-selective electrodes. In this model, NBP at the dose of 80, 160 and 240 mg/kg p.o. 15 min after MCAO prevented from brain edema in a dose-dependent manner. A significant reduction of sodium content and an increase in potassium level were observed in all drug-treated groups. It showed that NBP strongly attenuated brain water entry, sodium accumulation and potassium loss. Nimodipine treatment (5 mg/kg s.c.) also reduced brain edema (P < 0.05). The results suggest that a strong anti-edema activity of NBP may play an important role to contribute to the treatment of ischemic damage.

[A four-box multi-function testing system of pharmacology reaction]

The organism position matrix method, a new method of testing pharmacology reaction is proposed. On the basis of the method, we have developed a four-box multi-function testing system which can test the spontaneous activity, analgesic effect, and learning and memory ability of 1 to 4 mice in three dimensions respectively. Four quantitative parameters, the total distance, the movement intensity, the vertical number and the jumping number are put forward to describe the spontaneous activity. The starting time of continuous jumping and the jumping number are used to describe the analgesic effect. The time from the electrical shock to escape onto a safety platform and the number of the electrical shock are used to describe the learning and memory ability. The system has the characteristics of good repeatability, high efficiency, quantitative and automatic control.

[Some YAC contig construction and long range physical mapping at human X chromosome Xp11.3-21.3]

Human X chromosome short arm Xp11.3-p21.3 is an area, where several genetic disease gene loci are located. In this work, the YAC conting construction, long range physical mapping were done for this region. Some DNA probes and STS markers were used for YAC screening. Totally 77 YACs were obtained from the YAC libraries of CEPH, ICRF and ours. The size determination, 26 pairs of microsatelite STS analysis, single copy probe hybridization, Alu-PCR finger printing and long range physical mapping were conducted with these YACs. These results allowed us to map these YACs, and finally 6 YAC contigs were obtained in Xp11.3-21.3, covering about 15.3 Mb. This work will greatly facilitate the positional cloning of disease genes or the genome sequencing in this important region.

[Yeast artificial chromosome cloning and physical mapping of retinitis pigmentosa 3 (RP3) locus]

OBJECTIVE

To clone retinitis pigmentosa region by yeast artificial chromosome (YAC) and establish the restriction enzyme physical map.

METHODS

The ornithine transcarbamoylase (OTC) cDNA probe, which is closely linked to the RP3 locus, was chosen to screen the X chromosome YAC library by colony in situ hybridization. Size determination, sequence taged site (STS) analysis and long range physical mapping were performed with positive YACs. The results obtained were used to map these YACs.

RESULTS

We obtained a 1.6 Mb YAC contig containing information on RP3 range, restriction enzyme sites, CpG islands location and YAC position.

CONCLUSION

The work provides a good basis for identification and cloning of the RP3 gene.

LPS does not directly induce STAT activity in mouse macrophages

Induction of gene expression in cytokine-treated cells involves the protein tyrosine kinase-dependent activation of members of the STAT family of transcription factors. To determine if lipopolysaccharide (LPS) might activate one or more STAT factors, nuclear extracts from LPS-treated RAW264.7 macrophages were assayed for STAT-like DNA binding activity using oligonucleotides recognized by different members of this protein family. Within 30 min a single LPS-inducible DNA-protein complex was detected using three separate oligonucleotides. This activity was not reactive with anti-STAT antibodies and was subsequently identified as composed of the NF kappa B components NF kappa B1 and Rel-A. Thus, LPS does not directly stimulate STAT factors with known sequence-specific DNA binding activity.

T-DNA genes responsible for inducing a necrotic response on grape vines

Agrobacterium tumefaciens supervirulent strain A281 induces a progressive necrotic response, rather than tumor formation, when inoculated on stems of several grape cultivars. The Ti plasmid, and specifically its T-DNA, is required for the process. In the present study, 40 T-DNA insertion mutants of A281 were generated via transposon mutagenesis and tested for their necrosis-inducing ability on grape stems in vitro. Ten mutants were attenuated in inducing necrogenesis. Restriction mapping and DNA sequencing revealed that at least two genes, tms1 and 6b, whose gene products are involved in the synthesis and activity modulation of auxin, are responsible for inducing necrogenesis. Double mutants of tms1 and 6b were totally non-necrogenic. The orientation of grapevine stem explants showed strong effects on the occurrence and progress of necrogenesis. Inoculation of Agrobacterium on physiological basal ends resulted in the greatest degree of necrogenesis. In addition, gene 5 of T-DNA, which modulates auxin responses in plants by the autoregulated synthesis of an auxin antagonist, was found to be separated from other TL-DNA genes by a novel insertion sequence, IS1312. Since a T-DNA borderlike sequence occurs in IS1312, gene 5 might not always be transferred into plants. Based on the accumulated data, we propose that the necrogenesis induced by Agrobacterium results from the sensitivity of grapevine cells to elevated levels of auxin or a precursor of auxin.

Sequence and distribution of IS1312: evidence for horizontal DNA transfer from Rhizobium meliloti to Agrobacterium tumefaciens

Two novel insertion sequences, IS1312 and IS1313, were found in pTiBo542, the Ti plasmid of Agrobacterium tumefaciens strains Bo542 and A281. Nucleotide sequencing and Southern hybridization revealed that IS1312 and IS1313 are homologous to Rhizobium meliloti ISRm1 and ISRm2, respectively. IS1312, ISRm1, and another Agrobacterium insertion sequence, IS426, belong to the same IS3 family of insertion sequences; however, IS1312 is more closely related to the Rhizobium ISRm1 than it is to the Agrobacterium IS426. The distribution patterns of these insertion elements and their sequence similarities suggest that IS1312 and IS1313 were horizontally transferred from R. meliloti to A. tumefaciens.