Cell motility is required for the transmission of C-factor, an intercellular signal that coordinates fruiting body morphogenesis of Myxococcus xanthus

There are striking similarities between the developmental phenotypes of two different mutant classes of Myxococcus xanthus. The first class, mglA mutants, are nonmotile under all conditions tested. The second class, csgA mutants, are motile but belong to a class of signal-defective developmental mutants that cannot develop alone but will develop when mixed with intact wild-type cells. Nevertheless, both csgA and mglA mutants fail to aggregate properly or to sporulate when induced to form fruiting bodies. An mglA mutation and a csgA mutation affect expression of a panel of lacZ fusions to developmental genes in the same way, indicating that nonmotile cells and csgA cells arrest development at a similar stage. One explanation for the similarity of developmental phenotypes between these mutants is that motility is required for the csgA-mediated cell interaction. In support of this hypothesis, we report that C-factor, a protein purified from nascent wild-type fruiting bodies based on its ability to rescue csgA mutant fruiting body development, also rescues sporulation and expression of beta-galactosidase from developmentally controlled lacZ fusions in mglA strains, apparently without restoring their motility. Wild-type levels of active C-factor can be purified from mglA cells, yet intact mglA cells do not rescue csgA cells upon cell-cell mixing. Intact wild-type cells are unable to restore the sporulation and beta-galactosidase expression of mglA mutants. These results support the hypothesis that donor and responder cell motility is required for C-factor transmission between cells during development.(ABSTRACT TRUNCATED AT 250 WORDS)

Purification and properties of Myxococcus xanthus C-factor, an intercellular signaling protein

C-factor, a Myxococcus xanthus protein that restores the developmental defects of a class of nonautonomous mutants resulting from mutation of the csgA gene, has been purified approximately 1000-fold from starved wild-type cells. The monomeric form of C-factor is a single polypeptide with a molecular mass of 17 kDa that can be solubilized by detergent from membrane components. Characterization by gel filtration and denaturing gel electrophoresis suggests that biologically active C-factor is a dimer composed of two 17-kDa monomers. Antibodies against a form of the M. xanthus csgA gene product overexpressed in Escherichia coli react with purified C-factor.

Novel cysteine-rich motif and homeodomain in the product of the Caenorhabditis elegans cell lineage gene lin-11

The gene lin-11 is required for the asymmetric division of a vulval precursor cell type in the nematode Caenorhabditis elegans. Putative lin-11 complementary DNAs were sequenced and found to encode a protein that contains both a homeodomain and two tandem copies of a novel cysteine-rich motif: C-X2-C-X17-19-H-X2-C-X2-C-X2-C-X7-11-(C)-X8-C. Two tandem copies of this motif are also present amino-terminal to the homeodomains in the proteins encoded by the genes mec-3, which is required for C. elegans touch neuron differentiation, and isl-1, which encodes a rat insulin I gene enhancer-binding protein. The arrangement of cysteine residues in this motif, referred to as LIM (for lin-11 isl-1 mec-3), suggests that this region is a metal-binding domain. The presence in these three proteins of both a potential metal-binding domain and a homeodomain distinguishes them from previously characterized proteins.

C-factor: a cell-cell signaling protein required for fruiting body morphogenesis of M. xanthus

During fruiting body development, the product of the csgA gene is necessary for cellular aggregation, for spore differentiation, and for gene expression that is initiated after 6 hr of starvation. From nascent wild-type fruiting bodies we have purified a polypeptide of 17 kd called C-factor, which, at approximately 1 to 2 nM, restores normal development to csgA mutant cells. C-factor activity is not recovered from extracts of unstarved, growing cells or csgA mutant cells. The amino acid sequence from purified C-factor demonstrates that it is the product of the csgA gene. C-factor is active over a narrow range of concentration and has properties of a morphogenetic paracrine signal.

The Caenorhabditis elegans gene lin-10 is broadly expressed while required specifically for the determination of vulval cell fates

As a first step in a molecular dissection of the pathway controlling the determination of vulval cell fates in Caenorhabditis elegans, we have analyzed the gene lin-10. We show that loss-of-function mutations in this gene specifically prevent the induction of vulval cell lineages and result instead in the expression of hypodermal cell lineages. We isolated a transposon-insertion allele of lin-10 and used it to clone a genomic region that contains the lin-10 locus. The location of lin-10 within this region was determined by identifying a transcript affected by three independent lin-10 mutations and by delimiting the minimal segment of DNA sufficient to rescue the lin-10 mutant phenotype in germ line transformation experiments. The predicted lin-10 protein sequence is not similar to sequences in current data bases, suggesting that lin-10 defines a novel class of gene involved in the specification of cell fates. Although our genetic studies indicate that lin-10 is required specifically for the determination of vulval cell fates, lin-10 transcripts are present in cells other than vulval precursor cells. This result suggests that lin-10 may have a general but redundant role in development, functioning in diverse cell lineages to control cell fates. Alternatively, lin-10 may function specifically in vulval development, in which case lin-10 activity could be regulated at a post-transcriptional level or could have biological consequences only in conjunction with the products of other genes.

Expression of the glucose-regulated proteins (GRP94 and GRP78) in differentiated and undifferentiated mouse embryonic cells and the use of the GRP78 promoter as an expression system in embryonic cells

We examined the expression of GRP94 and GRP78 in embryonal carcinoma (EC) cells and during early mouse development. The GRP78 protein is constitutively expressed in the undifferentiated F9 cells whereas the level of GRP94 is below detection limit. These cells, like adult differentiated cells, exhibit enhancement of the GRP94 and GRP78 transcript levels in response to the calcium ionophore A23187, resulting in an increase of GRP94 and GRP78 proteins after 8 h of treatment. The GRP78 promoter has been identified as containing a strong enhancer. To test whether the GRP78 promoter is effective in directing expression of a heterologous gene in F9 cells, CAT fusion genes containing the GRP78 promoter were transfected into F9 cells. In non-induced F9 cells the activity of the GRP78 promoter was about 5- and 10-fold higher than the RSV promoter and the SV40 early promoter, respectively. Treatment of the cells with A23187 further increased the GRP78 promoter activity 3-fold. Since GRP78 is expressed during mouse embryogenesis and the promoter is also active in F9 cells treated with retinoic acid, the GRP78 promoter may be useful for the efficient expression of heterologous genes in undifferentiated and differentiated mouse embryonal cells.

Fluorescence line-narrowing spectrometry: a versatile tool for the study of chemically initiated carcinogenesis

An important initiating step in the induction of tumors is believed to be the covalent binding of an active carcinogenic species to a cellular macromolecule, e.g. DNA. Therefore, a spectroscopic technique which allows for positive identification of the intact (macromolecular) DNA adduct and/or isolated damaged nucleosides/nucleotides is highly desirable. It is shown that fluorescence line-narrowing spectroscopy (FLNS) is a rapid, versatile, highly sensitive and selective analytical technique, which can be used directly to characterize DNA adducts and isolated nucleosides. FLNS possesses sufficient resolution to distinguish between the major DNA adducts derived from different enantiomers of benzo[a]pyrene diol-epoxide (BPDE). With the present limit of detection (approximately 1 adducted base per 10(8) normal base pairs for 100 micrograms of DNA), the technique is applicable to in vivo samples. Analysis of liver DNA from fish exposed to benzo[a]pyrene (BP) (100 mg BP/kg fish) showed that a major DNA adduct is derived from syn-BPDE.

[Study on the changes in the upper airway following osteotomy for the mandibular prognathism]

This study was designed to compare pre-operation, immediate post-operation and over 6 month's follow-up for the mandibular prognathism in order to investigate the changes in the upper airway following mandibular osteotomy. The subjects were 18 patients. Their lateral cephalograms were taken pre-operatively, immediate post-operatively and over 6 months after operation and traced and analysed based on 10 selected items. The following conclusions were reached. 1) The downward displacement of the hyoid bone was recognized right after operation. (P less than 0.01) The hyoid bone tended to move to the original position in male group but not in female group. (P less than 0.01, P greater than 0.05) 2) The distance between the body of hyoid and posterior pharyngeal wall remained constant postoperatively (P greater than 0.05) 3) The distance between the body of hyoid and Menton was found to be shortened right after operation and remained constant thereafter. (P less than 0.01, P greater than 0.05) 4) The distance between the palate and the dorsum of tongue remained constant postoperatively. (P greater than 0.05) 5) The distance between the root of tongue and posterior pharyngeal wall was found to be shortened right after operation and remained constant thereafter. (P less than 0.01, P greater than 0.05) 6) APDI, SN-Pog, SNB and ANB remained constant during over 6 month's follow-up. (P greater than 0.05) 7) Relapse was found to show no correlation to other measurements.

[Clinical study on surgical treatment of zygoma fractures]

This is a retrospective statistical study on zygoma fractures. This study was based on 83 cases of zygoma fractures treated surgically in Dept. of Oral and Maxillofacial Surgery, Chungnam National University Hospital from May, 1985 to Sep., 1988. Among the many items the type of fractures and surgical methods were emphasized. For convenience sake, the zygoma fracture were classified according to Knight & North's classification. The results obtained are as follows: 1. The zygoma fractures occupied 31.9% of facial bone fractures. 2. The main age group were the second decade (37.5%) and the third decade (30.0%) and the ratio of mail and femail was 5.7:1. 3. The main contributing causes of fractures was traffic accident (71.3%). 4. The zygoma fractures were classified in 6 Group. Group 1. Undisplaced fractures were 8.4%. Group 2. Only arch fractures were 9.6% Group 3. Tripod with unrotated body were 32.5% Group 4. Tripod with medially rotated body were 20.5% Group 5. Tripod with laterally rotated body were 9.6% Group 6. Complex fractures were 19.2% 5. Fixation were required in 69 cases (83.1%) after adequate reduction. 6. Fixation area the most frequently used was zygomaticofrontal suture (71.1%), and infraorbital rim (43.3%), zygomatic arch (16.9%), zygomatic buttress (6%) were followed.

Fluorescence spectroscopy of benzo[a]pyrene diol epoxide-DNA adducts. Conformation-specific emission spectra

The fluorescence characteristics of adducts derived from the covalent binding of the highly tumorigenic (+) and the non-tumorigenic (-) enantiomers of trans-7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) to native calf thymus DNA are significantly different from one another both at room temperature and at 77 K. The ratio R of fluorescence intensities of the (0,0) band I (situated near 380 nm) and vibronic band V (near 400 nm) of the pyrene ring system in the BPDE-DNA adducts and of the tetraol (BPT) hydrolysis product of BPDE is very sensitive to the polarity of the solvent, thus mimicking the well known behavior of pyrene itself (A. Nakajima, 1971, Bull. Chem. Soc. Jpn. 44, 3272). The fluorescence excitation and emission spectra of the (+)-BPDE-DNA adducts are relatively sharp and only slightly red-shifted (2-3 nm) with respect to those of BPT in aqueous buffer solution, and R = 1.07 when the fluorescence is excited at the maximum of the absorption spectrum; this compares with R = 1.17 for BPT in water, R = 0.75 in ether, and R = 0.84 for noncovalently intercalated BPT. These results suggest that the pyrene ring system in the covalent (+)-BPDE-DNA adducts is located in an environment which is relatively exposed to the aqueous environment, while physically intercalated BPT molecules are located at hydrophobic binding sites. The fluorescence characteristics of the (-)-BPDE-DNA adducts are more heterogeneous and thus more complex than those of the (+)-adducts. The R ratio depends rather strongly on the wavelength of excitation; a minor, more highly fluorescent and relatively solvent-accessible form of adducts exhibits an R ratio of 1.01. The major, less solvent accessible form is characterized by a larger red shift in the absorption spectrum (approximately 10 nm) and emission spectrum (approximately 6 nm for the (0,0) band) relative to BPT, and an R ratio of 1.07. These characteristics suggest that the local environments of the pyrenyl residues in the (-)-BPDE-DNA adducts are significantly different from those of BPT bound noncovalently to DNA by the intercalation mechanism. Fluorescence methods, particularly at low temperatures where the bands are better resolved and the fluorescence yields are significantly greater than at room temperature, can also be used to distinguish covalent DNA adducts derived from the binding of (+)-BPDE and (-)-BPDE to native double-stranded DNA.

Potentiation of para-hydroxyamphetamine-induced head-twitch response by inhibition of monoamine oxidase type A in the brain

After pretreatment with either clorgyline, a monoamine oxidase (MAO)-A-selective inhibitor, or pargyline, an MAO-B-selective inhibitor with less selectivity than l-deprenyl, i.c.v. administration of para-hydroxyamphetamine (p-OHA) significantly increased both the frequency and total number of head-twitches in mice. A typical MAO-B-selective inhibitor, l-deprenyl, however, did not change the total count of the p-OHA-induced head-twitch response (HTR). These effects were also found with fixed doses of the selective MAO inhibitors when p-OHA was varied. Administration of clorgyline (1 mg/kg) or pargyline (5 mg/kg) almost inhibited completely MAO-A in the mouse forebrain, and pargyline also almost inhibited completely MAO-B. l-Deprenyl, in contrast, almost inhibited completely MAO-B without affecting MAO-A activity. Systemic administration of l-5-hydroxytryptophan also induced HTR and the total number of twitches was enhanced by clorgyline, but not by pargyline or l-deprenyl. Chlorimipramine or cocaine significantly reduced p-OHA-induced HTR, suggesting an intraneuronal site of action. Together with the presence of considerable MAO-A in 5-hydroxytryptamine (5-HT) neurons of various animal species, and possible accumulation and subsequent monoamine-releasing properties of p-OHA, the present results indicate that p-OHA might induce the HTR by interaction with intraneuronally increased 5-HT. This mechanism probably results in 5-HT release onto the postsynaptic 5-HT2 receptors. Taken together, different roles of MAO-B in "the hyperactivity syndrome" and the HTR are discussed.

Identification of conformationally different binding sites in benzo[a]pyrene diol epoxide--DNA adducts by low-temperature fluorescence spectroscopy

It is known that the covalent binding of the two enantiomers of trans-7,8-diol-anti-9,10-epoxy-benzo[a]pyrene (BPDE) to native double-stranded DNA gives rise to two distinct classes of adducts. Type I adducts involve significant interactions of the pyrenyl residues with the DNA bases and are similar but not identical to intercalation complexes. Type II adducts involve external solvent-exposed binding sites and their predominance in adducts derived from the covalent reaction of (+)-BPDE with DNA has been associated with the higher tumorigenicity and mutagenic activity of (+)-BPDE in mammalian cells. These two distinct binding sites in covalent BPDE-DNA adducts can be readily resolved by synchronous scanning fluorescence methods at low temperatures (77 K) using commercially available fluorescence spectrophotometers. The site I adducts are particularly unstable in the presence of UV light, and this method can be used to follow their selective photodegradation.

Excited state properties of the N-(deoxyguanosin-8-yl)-2-aminofluorene adducts

The spectroscopic characteristics of adducts derived from the covalent binding of the carcinogen 2-aminofluorene to the C8 position of deoxyguanosine [N-(deoxyguanosin-8-yl)-2-amino-fluorene, dGuo-C8-AF], and from an adduct of similar structure formed with the synthetic polynucleotide poly(dG-dC).poly(dG-dC), were investigated. At 77 K both adducts are characterized by well-defined and rather narrow fluorescence emission spectra with maxima at 370 and 390 nm characteristic of the aromatic, monomolecular 2-aminofluorene (AF) residue. In contrast, at room temperature, the fluorescence is characterized by a broad, structureless emission band with a maximum at 460 nm in aqueous mixtures, shifting to 415 nm in solvents of lower polarity (100% propanol); the maxima are located at intermediate wavelengths in solutions of different propanol/water compositions, and this emission is attributed to an excited state complex (exciplex). The fluorescence quantum yield decreases when either the solvent polarity or the temperature are increased, varying from 5.4% (100% propanol) to 0.04-0.05% (100% H2O). The fluorescence decay profiles of dGuo-C8-AF adducts (measured at the National Synchrotron Light Source facility at the Brookhaven National Laboratory) can be roughly, but not exactly, modeled in terms of two exponential decay components in the range of about 0.3-1.0 ns with the propanol concentration greater than 60%; at lower propanol concentrations, a single short lifetime is observed and in 100% water solutions its value is 0.08 ns. The shorter lifetime, favored in solvent mixtures of higher polarities, is attributed to an exciplex with significant charge-transfer character.(ABSTRACT TRUNCATED AT 250 WORDS)

Phase II study of cyclophosphamide, doxorubicin, and vincristine (CAV) and etoposide plus cisplatin (EP) alternating chemotherapy combined with radiotherapy in small cell lung cancer

The development of drug resistance is the major limiting factor influencing the survival of patients with small cell lung cancer (SCLC). We have thus examined the activity of cyclophosphamide, doxorubicin and vincristine (CAV) alternating with etoposide and cisplatin (EP) in 35 patients with SCLC. The treatment courses were alternated every 3 or 4 weeks. After induction chemotherapy, patients with limited disease (LD) received thoracic radiotherapy (5000 cGy), prophylactic cranial irradiation (3000 cGy) and maintenance chemotherapy and patients with extensive disease (ED) received maintenance chemotherapy only. In this group of 35 patients, 13 had limited disease (LD) and 22 had extensive disease (ED). After completion of the therapy, 100% of the patients with LD achieved complete plus partial remission (CR + PR) and 68% of the patients with ED achieved CR + PR. The median survival time was 66 weeks (15.3 months) in patients with LD and 44 weeks (10.2 months) in patients with ED. The over all survival for patients with LD was superior to that for patients with ED (p less than 0.05). Also, median response duration for patients with LD (35 wks) was longer than that for patients with ED (17 weeks) (p less than 0.05). The primary site was the most vulnerable site to relapse (18 patients). Toxicity was mild to moderate and acceptable, and there were no treatment-related deaths. These results suggest that the alternation of CAV and EP is effective treatment strategy in the management of SCLC. A randomized controlled study will be required to discriminate the actual effect of this alternating regimen.