Heat shock response and cytotoxicity in C6 rat glioma cells: structure-activity relationship of different alcohols

In C6 rat glioma cells, the n-alcohols methanol, ethanol, propanol, and butanol and the aromatic alcohol phenol all induce heat shock proteins (HSPs) of high molecular mass (68, 70, 90, and 110 kDa) when applied for 1 hr. The lowest alcohol concentrations that induce HSP synthesis cause about 20% cell death, as determined by neutral red assay. HSP induction thus occurs at alcohol concentrations close to the highest tolerable dose. The cytotoxicity and the potential of alcohols to induce the synthesis of HSPs increase with chain length and are correlated with the lipophilicity of the alcohols. A clear structure-activity relationship is observed for both parameters. A calculation of the putative membrane concentrations of these alcohols reveals that cytotoxic effects (50% cell death) occur at nearly the same membrane concentration (approximately 0.2 M). This also holds true for the lowest HSP 68-inducing alcohol concentrations, but at a lower concentration (approximately 0.12 M). The activities of major proteinases are affected by both heat shock and alcohols. The effects of alcohols also depend on the lipophilicity of the alcohols. Effective concentrations again are close to the highest tolerable dose. The stress reactions measured in terms of significant changes in HSP synthesis and proteinase activity provide information about the mechanisms by which toxic agents act on the cell.

Lineage-specific and differentiation-dependent expression of K12 keratin in rabbit corneal/limbal epithelial cells: cDNA cloning and northern blot analysis

Corneal epithelial cells synthesize an acidic (55 kDa) K12 and a basic (64 kDa) K3 keratin as their major differentiation products during an advanced stage of differentiation. In this paper, we describe the cDNA cloning of rabbit K12 keratin. We used a 36 base pairs (bp) oligonucleotide corresponding to a consensus sequence of many known acidic keratins as a probe to screen a cDNA library of normal rabbit corneal epithelium. Several partial cDNA clones were isolated. Hybrid-selection showed that the 3'keratin chain-specific portion of the cDNA hybridizes with K12 mRNA. A rabbit antiserum raised against the C-terminus of the cDNA-deduced amino acid sequence recognizes, in immunoblotting, the K12 keratin. In situ hybridization showed that K12 mRNA is present in all cell layers of central corneal epithelium, but in only the suprabasal cells of limbal epithelium indicating a parallel expression pattern between K12 and K3. Cultured rabbit corneal epithelial cells initially synthesize K14/K5 keratins, but later when the cells become heavily stratified they synthesize large quantities of K12 and K3 mRNAs, as detected by Northern blotting. Cultured esophageal epithelial cells do not make K12 mRNA confirming the tissue-specificity of K12 expression. Although it has been suggested that conjunctival epithelial cells can trans-differentiate into a bona fide corneal epithelium, we showed here that cultured conjunctival cells do not synthesize significant amounts of K12/K3 mRNAs. These results strongly suggest that conjunctival epithelial cells, whose differentiation can be modulated significantly by the extracellular matrix, form a lineage intrinsically distinct from the corneal/limbal epithelial lineage.

cDNA cloning of a mouse factor that activates transcription from a metal response element of the mouse metallothionein-I gene in yeast

A cDNA that encodes a mouse factor that activates expression from a metal response element of the mouse metallothionein-I gene has been isolated by complementation cloning in yeast cells. The cDNA encodes a peptide with a maximum length of 99 amino acids that includes a single zinc finger sequence. In yeast cells, the cloned factor induces transcription from the metal response element in a sequence-specific but metal-independent fashion. The cDNA hybridizes to a 550-base mRNA that is constitutively expressed in mouse tissue culture cells. The ability of the mouse factor to activate transcription in yeast cells is dependent upon the carbon source.

Identification of a cDNA for a human high-molecular-weight B-cell growth factor

Proliferation is necessary for many of the phenotypic changes that occur during B-cell maturation. Further differentiation of mature B cells into plasma cells or memory B cells requires additional rounds of proliferation. In this manuscript, we describe a cDNA for a human B-cell growth factor we call high-molecular-weight B-cell growth factor (HMW-BCGF). Purified HMW-BCGF has been shown to induce B-cell proliferation, inhibit immunoglobulin secretion, and selectively expand certain B-cell subpopulations. Studies using antibodies to HMW-BCGF and its receptor have suggested that HMW-BCGF, while produced by T cells and some malignant B cells, acts predominantly on normal and malignant B cells. The HMW-BCGF cDNA was identified by expression cloning using a monoclonal antibody and polyclonal antisera to HMW-BCGF. Protein produced from the cDNA induced B-cell proliferation, inhibited immunoglobulin secretion, and was recognized in immunoblots by anti-HMW-BCGF antibodies. The amino acid sequence of HMW-BCGF deduced from the cDNA predicts a secreted protein of 53 kDa with three potential N-linked glycosylation sites. The identification of this cDNA will allow further studies examining physiologic roles of this cytokine. We propose to call it interleukin 14.

[Study on determination of polyactin A by ELISA]

Sandwich ELISA and two-step competition ELISA were utilized to determine polyactin A. After optimization of the experimental conditions, microtiter plates were coated with the rabbit antibody solution and evaporated to dryness at 37 degrees C. The coated microtiter plates were incubated first with the analyte, then with the HRP-labelled antibody (sandwich procedures), or with the HRP-labelled polyactin A (competition procedures), and absorbance was measured after coloration. The whole determination took less than 4 hours, excluding the coating procedure, which is faster than the routine complement fixation method. The coated microtiter plates can be well after over three months of storage at 4 degrees C. The sensitivity obtained was 0.64-7.4 ng/well for the sandwich method or 0.6-1.2 micrograms/well for the competition method.

A 300 bp 5′-upstream sequence of a differentiation-dependent rabbit K3 keratin gene can serve as a keratinocyte-specific promoter

Keratinocytes of the suprabasal compartment of many stratified epithelia synthesize as a major differentiation product a keratin pair, consisting of an acidic and a basic keratin, which accounts for 10–20% of the newly synthesized proteins. While genes of several differentiation-related keratins have been cloned and studied, relatively little is known about the molecular basis underlying their tissue-specific and differentiation-dependent expression. We have chosen to study, as a prototype of these genes, the gene of K3 keratin, which has the unique property of being expressed in the majority of corneal epithelial basal cells but suprabasally in peripheral cornea, the site of corneal epithelial stem cells. Using a monoclonal antibody, AE5, specific for K3 keratin, and a fragment of human K3 gene as probes, we have isolated several cDNA and genomic clones of rabbit K3 keratin. One genomic clone has been sequenced and characterized, and the identity of its coding sequence with that of cDNAs indicates that it corresponds to the single, functional rabbit K3 gene. Transfection assays showed that its 3.6 kb 5′-upstream sequence can drive a chloramphenicol acetyl transferase (CAT) reporter gene to express in cultured corneal and esophageal epithelial cells, but not in mesothelial and kidney epithelial cells or fibroblasts, all of rabbit origin. Serial deletion experiments narrowed this keratinocyte-specific promoter to within -300 bp upstream of the transcription initiation site. Its activity is not regulated by the coding or 3′-noncoding sequences that have been tested so far. This 300 bp 5′-upstream sequence of K3 keratin gene, which can function in vitro as a keratinocyte-specific promoter, contains two clusters of partially overlapping motifs, one with an NFkB consensus sequence and another with a GC box. The combinatorial effects of these multiple motifs and their cognate binding proteins may play an important role in regulating the expression of this tissue-restricted and differentiation-dependent keratin gene.

Isolation of proteins associated with kinetoplast DNA networks in vivo

Kinetoplast DNA (kDNA), the mitochondrial DNA of trypanosomes, is a highly condensed disc-shaped network of catenated DNA circles consisting of maxicircles, the equivalent of conventional mitochondrial DNA, and several thousand smaller circular DNAs termed minicircles. Upon cell lysis, kDNA expands, giving rise to a two-dimensional network of catenated circles with an overall diameter close to that of the whole cell. To identify proteins associated with the condensed form of kDNA in the cell, proteins were reversibly crosslinked to kDNA in whole cells of Crithidia fasciculata by formaldehyde treatment. Crosslinked networks were purified and found to retain a condensed structure which becomes fully expanded upon proteinase K treatment or reversal of the crosslinks by heating at 65 degrees C. Five low molecular weight proteins released from the kDNA by heat treatment were purified by polyacrylamide gel electrophoresis and their amino-terminal sequences were determined. PCR amplification and sequence analysis of cDNA sequences between these amino-terminal sequences and the miniexon (spliced leader) sequence present at the 5' end of all C. fasciculata mRNAs predicts the presence of 9-amino acid presequences with features characteristic of mitochondrial presequences on three of the proteins. Two of these proteins are lysine-rich basic proteins. These findings suggest that basic proteins may play a role in the condensation of kDNA in the kinetoplast and that these proteins are imported into the kinetoplast by a mechanism involving a cleavable presequence.

[Preparation of sucking tablet of shengmei] off

The Sucking Tablet of Shengmei is made from eight Chinese traditional drugs including Radix Adenophorae, Fructus Mume, etc. The effective rate of the tablet in treating chronic pharyngitis reaches up to 96 percent. The working mechanism related to the fact that the tablet is bacteria-resistant and helps to strengthen the body function. This paper presents the preparation process of the Sucking Tablet along with solutions for some problems encountered in the process and appropriate standards for quality control.

Similarity between the Myxococcus xanthus and Stigmatella aurantiaca reverse transcriptase genes associated with multicopy, single-stranded DNA

To determine the evolutional relationship of bacterial retroelements of Myxococcus xanthus and Stigmatella aurantiaca, the nucleotide sequence of 3,060 bases encompassing msr, msd, and the upstream region of msd (downstream of msr) of S. aurantiaca DW4 was determined and compared with the same region from M. xanthus. An open reading frame was found 92 bases upstream of msd which encoded a polypeptide of 480 amino acid residues having 73% identity with the reverse transcriptase of M. xanthus. Together with high homologies in msr (86%) and msd (81%) regions, the present data indicate that the reverse transcriptase genes as well as the retrons of M. xanthus (retron-Mx162) and S. aurantiaca (retron-Sa163) were derived from a common progenitor retron which possibly before the two myxobacterial species diverged.

[A study on autoimmune response against spermatozoa following intravas deferens injection of high molecular hydrogel HFMC in rabbits]

To investigate whether intravas injection of HFMC can result in antisperm antibodies, we divided 30 fertile male rabbits into the DMSO, 10% HFMC and 20% HFMC groups. Two to 8 months after intravas injection of the agents, we collected the sera per month and used ELISA to detect the serum antisperm antibodies, The results showed that there are lower antisperm antibody levels in the sera of DMSO, 10% HEMC and 20% HFMC groups in the first 2 months (P less than 0.05), but no significant difference between the antibody levels of DMSO, 10% and 20% HFMC groups and that of the control group from the 3rd month to the 8th month (P greater than 0.05). No immune-related pathological changes were found in the testis and epididymis. Intravas injection of HFMC in the rabbits appears to be a safe method of contraception that causes no deleterious effects.

[Effects of verticillatine on cerebral blood flow, cerebral vascular resistance and blood pressure in anesthetized dogs and cats]

The effects of verticillatine (Ver), hexamethonium (Hex) and nimodipine (Nim) on mean arterial pressure (MAP), cerebral blood flow (CBF) and cerebrovascular resistance (CVR) were determined in pentobarbital anesthetized animals using the method of electromagnetic flow meter in dogs and hydrogen clearance in cats. Ver or Nim iv induced significant reduction of MAP and CVR. CBF was increased in dogs and unaltered in cats. The Hex treated dogs and cats exhibited a fall of MAP and CBF with enhancement of CVR. In cats after middle cerebral artery occlusion (MCAO), regional cerebral blood flow (rCBF) was reduced from 190 +/- 70 to 90 +/- 20 ml.kg-1.min-1. Ver and Nim iv caused similar changes of MAP and CVR to those before MCAO. The results suggest that Ver and Nim may have vasodilation effect and improve the cerebral circulation. Thus, they would be beneficial to patients suffering from hypertension.

Ventilatory response of the sleeping newborn to CO2 during normoxic rebreathing

The ventilatory response of the newborn to CO2 was studied using a rebreathing method that minimized changes in arterial PO2 during the test. The aim was to study the variability of the ventilatory response to CO2 and take this into account to assess the relative magnitude of the response to CO2 during rapid-eye-movement (REM) sleep and quiet sleep (QS). Five full-term babies aged 4-6 days were given 5% CO2 in air to rebreathe for 1.5-3 min. O2 was added to the rebreathing circuit to maintain arterial O2 saturation and transcutaneous PO2 (Ptco2) at prerebreathing levels. Tests were repeated four to five times in REM sleep and QS. Mean Ptco2 levels varied between individuals but were similar during REM sleep and QS tests for each subject. The mean coefficient of variability of the ventilatory response was 35% (range 15-77%) during QS and 120% (range 32-220%) during REM sleep. PtcO2 fluctuations during tests [6.0 +/- 3.0 (SD) Torr, range 1-13 Torr] were not correlated with ventilatory response. Overall the ventilatory response was significantly lower in REM sleep than in QS (12.2 +/- 3.0 vs. 38.7 +/- 3.0 ml.min-1.Torr-1.kg-1, P less than 0.001; 2-way analysis of variance) due to a small (nonsignificant) fall in the tidal volume response and a significant fall in breathing rate. In 12 REM sleep tests there was no significant ventilatory response; mean inspiratory flow increased significantly during 8 of these 12 tests. We conclude that there is a significant decrease in the ventilatory response of the newborn to CO2 rebreathing during REM sleep compared with QS.

Activated macrophages in highly irradiated cercariae-induced immunity to Schistosoma japonicum in rats

The results of studies on the schistosomulicidal activity of activated peritoneal and alveolar macrophages (pM phi and aM phi) from rats immunized with highly irradiated (50 krad.) Schistosoma japonicum cercariae are reported. The authors have examined the activation of these macrophages in terms of spreading, adhesion and ingestion of sheep erythrocytes and pinocytosis of horse-radish peroxidase. Using three criteria, peritoneal macrophages and alveolar macrophages from immunized rats and from rats intraperitoneally injected with BCG were significantly more active than those from normal rats or rats stimulated with 10% proteose-peptone or 1% sodium thioglycolate. A significantly higher percentage of adhesion and ingestion was obtained with the sheep erythrocytes that were co-opsonized by heat-inactivated rat anti-sheep erythrocyte serum and fresh normal rat serum. Schistosomulicidal effects were observed with macrophages from irradiated cercariae-immunized rats in two activation systems: in vitro activation in the presence of macrophage-activating factor (MAF), and in vivo activation by the intraperitoneal challenge with sonicated cercarial antigens.

[Action of traditional Chinese medicines on DNA reproduction in liver cells in vitro]

The action of 11 kinds of traditional Chinese medicine on DNA reproduction in hepatic cells was studied with microradiographic auto-development. The result shows that all the medicines can promote and strengthen the DNA reproduction.

Uroplakin I: a 27-kD protein associated with the asymmetric unit membrane of mammalian urothelium

The luminal surface of mammalian urothelium is covered with numerous plaques (also known as the asymmetric unit membrane or AUM) composed of semi-crystalline, hexagonal arrays of 12-nm protein particles. Despite the presumed importance of these plaques in stabilizing the urothelial surface during bladder distention, relatively little is known about their protein composition. Using a mouse mAb, AE31, we have identified a 27-kD protein that is urothelium-specific and is differentially expressed in superficial umbrella cells. This protein (pI approximately 5.8) partitions into the detergent phase during Triton X-114 phase separation. Pulse-chase experiments using cultured bovine urothelial cells showed that this protein is synthesized as a 32-kD precursor that is processed through a 30-kD intermediate, to the mature 27-kD form. In cytoplasmic vesicles containing immature AUM, the AE31 epitope is detected in patches on the cytoplasmic side, but in mature, apical AUM it is detected exclusively on the luminal side. This suggests an unusual translocation of the AE31 epitope during AUM maturation; more data are required, however, to substantiate this interpretation. Immunoaffinity purification of the 27-kD protein results in the copurification in approximately molar ratio of a 15-kD protein, as well as a small and variable amount of a 47-kD protein. Immunoblotting data indicate that these three proteins are immunologically distinguishable. This copurified 15-kD protein is relative basic (pI approximately 8.0). Like the 27-kD protein, it is urothelium-specific and is present mainly in the umbrella cells. Together, our data indicate that a 27-kD protein is urothelial plaque-associated (uroplakin I). Based on complex formation data, we provisionally name the 15-kD protein uroplakin II; additional data will be required to determine whether this and the 47-kD protein are integral parts of AUM. The identification of these AUM-associated and -related proteins, plus the availability of a culture system capable of synthesizing and processing some of these molecules, offer new opportunities for studying the detailed structure, assembly, and function of asymmetrical unit membrane.

[Influence of culture conditions on the growth of murine bone marrow stromal colony-forming cells (CFU-f) in vitro]

Several factors which may influence the colony-forming efficiency of mouse CFU-f, including media, culture dishes, mouse strains, and O2 concentrations in the incubator were tested. Among them, the O2 concentration was found to be the most important factor, when a mixed gas consisting of 5% O2, 5% CO2 and 90% N2 was used to replace the usual 5% CO2 in air, the colony-forming efficiency of CFU-f increased markedly and the influence of other factors on cell growth diminished. Although the use of a lit candle to consume O2 in the air provided good conditions for colony formation of several tumor cell lines in soft agar, it is not suitable for the growth of CFU-f.

[Fragile sites of cultured peripheral blood lymphocyte chromosomes in patients with gestational trophoblastic tumor]

Chromosomal aberrations were studied on peripheral blood lymphocytes from 16 women with gestational trophoblastic tumor (GTT) before chemotherapy or radiotherapy and from 15 age-matched normal women. The chromosomal aberration rate of the patients (19.6%) was significantly higher than that of the normal women (7.0%). Successful G-banding site analysis revealed 241 breaks and gaps consistent with the common fragile sites. Among these fragile sites, there were 45 breaks and gaps at the same locations of some oncogenes. There was no significant differences of chromosome aberration rate (P greater than 0.05) between 11 patients with GTT who recovered after chemotherapy and 15 control women.

Chlorophyll a fluorescence measurements of isolated spinach thylakoids obtained by using single-laser-based flow cytometry

Flow cytometry data of spinach thylakoid membrane preparations indicate the presence of a homogeneous thylakoid population. Fluorescence data from a flow cytometer and comparison with data from two other fluorometers show that chlorophyll a fluorescence detected with a flow cytometer has the character of maximum fluorescence (Fmax), not of the constant component (Fo). This conclusion is important since Fo measures fluorescence that is affected mostly by changes in excitation energy transfer and Fmax-Fo (the variable fluorescence) by changes in photochemistry. This was demonstrated by: 1) The light intensity as well as diffusion rate dependence of the quenching effect of various quinones (p-benzoquinone, phenyl-benzoquinone, and 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone, DBMIB) on fluorescence yield; quenching for the same concentration of these quinones was lower at the higher than at the lower light intensities. 2) Temperature dependence of the fluorescence yield; increasing the temperature from 20 to 70 degrees C did not show an increase in fluorescence yield using a flow cytometer in contrast to measurements with weak excitation light, but similar to those obtained for Fmax. 3) Addition of an inhibitor diuron up to 100 microM did not change the fluorescence intensity. A comparison of quenching of fluorescence by various quinones obtained by flow cytometry with those by other fluorometers suggests that the high intensity used in the cytometry produces unique results: the rate of reduction of quinones in much larger than the rate of equilibration with the bulk quinones.

Fluorescence characteristics of photoautotrophic soybean cells

We report here the first measurements on chlorophyll (Chl) a fluorescence characteristics of photoautotrophic soybean cells (cell lines SB-P and SBI-P). The cell fluorescence is free from severe distortion problems encountered in higher plant leaves. Chl a fluorescence spectra at 77 K show, after correction for the spectral sensitivity of the photomultiplier and the emission monochromator, peaks at 688, 696 and 745 nm, representing antenna systems of photosystem II-CP43 and CP47, and photosystem I, respectively. Calculations, based on the complementary area over the Chl a fluorescence induction curve, indicated a ratio of 6 of the mobile plastoquinone (including QB) to the primary stable electron acceptor, the bound plastoquinone QA. A ratio of one between the secondary stable electron acceptor, bound plastoquinone QB, and its reduced form QB (-) was obtained by using a double flash technique. Owing to this ratio, the flash number dependence of the Chl a fluorescence showed a distinct period of four, implying a close relationship to the 'S' state of the oxygen evolution mechanism. Analysis of the QA (-) reoxidation kinetics showed (1) the halftime of each of the major decay components (∼ 300 μs fast and ∼ 30 ms slow) increases with the increase of diuron and atrazine concentrations; and (2) the amplitudes of the fast and the slow components change in a complementary fashion, the fast component disappearing at high concentrations of the inhibitors. This implies that the inhibitors used are able to totally displace QB. In intact soybean cells, the relative amplitude of the 30 ms to 300 μs component is higher (40:60) than that in spinach chloroplasts (30:70), implying a larger contribution of the centers with unbound QB. SB-P and SBI-P soybean cells display a slightly different sensitivity of QA (-) decay to inhibitors.

Preparation of misacylated aminoacyl-tRNA(Phe)'s useful as probes of the ribosomal acceptor site

Several pyroglutamylaminoacyl-tRNA's were prepared by T4 RNA ligase mediated condensation of synthetic pyroglutamylaminoacyl-pCpA's with tRNA's from which the last two nucleotides at the 3'-end had been removed. The derived pyroglutamylaminoacyl-tRNA's were incubated in the presence of calf liver pyroglutamate aminopeptidase, which effected their conversion to free aminoacyl-tRNA's. The lack of contaminating esterase activities in the pyroglutamate aminopeptidase was verified by direct assay for the presence of the aminoacyl moieties in the formed aminoacyl-tRNA's and by the use of the deblocked aminoacyl-tRNA's as acceptors in the peptidyltransferase reaction using an Escherichia coli ribosomal system. These findings provide the wherewithal for a detailed investigation of the substrate specificity of the peptidyltransferase center and for the elaboration of polypeptides containing modified amino acids at predetermined sites.

Expression of hair-related keratins in a soft epithelium: subpopulations of human and mouse dorsal tongue keratinocytes express keratin markers for hair-, skin- and esophageal-types of differentiation

The dorsal surfaces of mammalian tongues are covered with numerous projections known as filiform papillae whose morphology varies in different species. Using a panel of monoclonal antibodies to keratins as probes, we have established that, in both human and mouse, the interpapillary epithelia express mainly the "esophageal-type" keratins, while the papillary epithelia express "skin-type" keratins as well as some keratins reacting with a monoclonal antibody (AE13) to hair keratins. The AE13-reactive proteins of the mouse were found to be very similar to those of authentic mouse hair keratins. However, the corresponding protein of human tongue appears to be different from all known human keratins. This protein has a MW of 51K; it is relatively acidic; it is sulfhydryl-rich, as revealed by iodoacetic acid-induced charge and apparent size shift; it shares an epitope with all the known acidic human hair keratins; and it is associated with keratin fibrils in vivo. This protein may therefore be regarded as a novel type I "hard" keratin. These data establish that mammalian dorsal tongue epithelia can be divided into at least three compartments that undergo mainly "esophageal-", "skin-" and "hair"-types of differentiation. Different keratin filaments, e.g., those of the esophageal- and hair-types, exhibit strikingly different degrees of lateral aggregation, which can potentially account for the different physical strength and rigidity of various cellular compartments. Our data also suggest the possibility that variations in papillary structure in human and mouse may arise from different spatial arrangements of specific keratinocytes, and/or from the expression of specialized hair-related keratins.

Characteristics of Five New Photoautotrophic Suspension Cultures Including Two Amaranthus Species and a Cotton Strain Growing on Ambient CO(2) Levels

Suspension cultures of cotton (Gossypium hirsutum), Amaranthus cruentus, A. powellii, Datura innoxia, and a Nicotiana tabacum-N. glutinosa fusion hybrid were adapted to grow photoautotrophically under continuous light. The cotton strain grew with an atmosphere of ambient CO(2) (about 0.06 to 0.07% in the culture room) while the other strains required elevated CO(2) levels (5%). Photoautotrophy was indicated by the requirement for CO(2) and for light for growth. The strains grew with doubling times near 14 days and had from 50 to 600 micrograms of chlorophyll per gram of fresh weight. The cells grew in small to moderate sized clumps with cell sizes from 40 to 70 micrometers (diameter). Like most photoautotrophic cultures described so far the ribulose 1,5-bisphosphate carboxylase (RuBPcase) activity levels were well below those of mature leaves. The phosphoenolpyruvate carboxylase levels were not elevated in the C(4)Amaranthus species. The cells showed high dark respiration rates and had lower net CO(2) fixation under high O(2) conditions. Dark CO(2) fixation rates ranged from near 10 to 30% of that in light. Fluorescence emission spectra measurements show that the cell antenna pigments systems of the four strains examined are similar to that of chloroplasts of green plants. The cotton strain which was capable of growth under ambient CO(2) conditions showed the unique properties of a high RuBPcase activation level in ambient CO(2) and a stable ability to show net CO(2) fixation in 21% O(2) conditions.

Ribosomal binding and dipeptide formation by misacylated tRNA(Phe),S

Eight structurally modified peptidyl-tRNA(Phe),s were employed to study P-site binding and peptide bond formation in a cell-free system involving Escherichia coli ribosomes programmed with poly(uridylic acid). It was found that the two analogues (N-acetyl-D-phenylalanyl-tRNA(Phe) and N-acetyl-D-tyrosyl-tRNA(Phe] containing D-amino acids functioned poorly as donors in the peptidyltransferase reaction and that two N-acetyl-L-phenylalanyl-tRNA(Phe)'s differing from the prototype substrate in that they contained 2'- or 3'-deoxyadenosine at the 3'-terminus failed to form dipeptide at all when L-phenylalanyl-tRNA(Phe) was the acceptor tRNA. Interestingly, all four of these peptidyl-tRNA's bound to ribosomes to about the same extent as tRNA's that functioned normally as donors in the peptidyltransferase reaction, at least in the absence of competing peptidyl-tRNA species. Two peptidyl-tRNA's lacking an amino group were also tested. In comparison with N-acetyl-L-phenylalanyl-tRNA(Phe) it was found that trans-cinnamyl-tRNA(Phe) and 3-phenylpropionyl-tRNA(Phe)'s formed dipeptides to the extent of 53 and 80%, respectively, when L-phenylalanyl-tRNA(Phe)was used as the acceptor tRNA. N-Acetyl-beta-phenylalanyl-tRNA(Phe) was found to be the most efficient donor substrate studied. Both isomers transferred N-acetyl-beta-phenylalanine to L-phenylalanyl-tRNA(Phe); the nature of the dipeptides formed in each case was verified by HPLC in comparison with authentic synthetic samples. Further, the rate and extent of peptide bond formation in each case exceeded that observed with the control tRNA, N-acetyl-L-phenylalanyl-tRNA(Phe).

Chemistry of the alkali-labile lesion formed from iron(II) bleomycin and d(CGCTTTAAAGCG)

Two sets of products are formed from DNA upon treatment with Fe(II).bleomycin + O2. One set, which is believed to derive from a C-4' hydroperoxy derivative of the DNA deoxyribose moiety, includes the four possible base propenals, as well as DNA oligomers having deoxynucleoside 3'-(phosphoro-2"-O-glycolates) at their 3'-termini. The other set of products consists of free bases and alkali-labile lesions, the latter of which had not previously been characterized structurally. By use of the self-complementary dodecanucleotide d(CGCTTTAAAGCG) having a site modified by Fe-bleomycin three nucleotides from the 5'-end, it has been possible to characterize the alkali-labile product as a C-4' hydroxyapurinic acid. When the bleomycin-treated dodecanucleotide was treated with agents that effected decomposition of the alkali-labile lesion, products of the form CpGpx were obtained, and these proved useful for structural characterization of the alkali-labile lesion. Treatment with alkali produced CpGpx, where x was 2,4-dihydroxycyclopentenone. Alternatively, treatment with hydrazine provided a pyridazine derivative, and aqueous alkylamines led to formation of CpGp itself. The structures of all dinucleotides produced from the alkali-labile lesion were verified by direct comparison with authentic synthetic samples.

The influence of proglumide, a putative CCK antagonist, on cerebral ischemia in gerbil

Studies were conducted to clarify the possible role of CCK in cerebral ischemia and to evaluate the effects of proglumide, a competitive and reversible CCK antagonist, as a potential therapeutic or prophylactic tool in the treatment of cerebral ischemia. Proglumide at the doses of 10, 50 and 150 mg/kg was administered to gerbils before unilateral carotid ligation, and its effect on stroke index score, incidence and mortality rate was observed. Our results show that proglumide injected prior to carotid ligation at the dose of 150 mg/kg significantly reduces both incidence and mortality rate and changes the distribution of the stroke index score in gerbils. There was a significant inverse relationship between the dose of proglumide and both incidence and mortality: the greater the injection dose of proglumide, the lower the incidence and mortality. These results suggest that CCK may be involved in the pathological processes of cerebral ischemia and proglumide or related compounds prove to be effective in the pharmacological prophylaxis of ischemic brain damage.

Differences in immunogenicity indicating polymorphism of sperm antigens from mice of different inbred strains

Polymorphism of mouse sperm was investigated by analysis of immune sera generated in BALB/c female mice against sperm from 6 inbred strains. The immune sera were analyzed by immunofluorescence and Western blot techniques against sperm antigens from the 6 immunizing strains. Immunofluorescence revealed no differences in reactivity patterns or titers. However, several different reaction patterns were detected by Western blot technique which indicated that both the sperm extracts and the antisperm immune sera contained different components. Syngeneic (anti-BALB/c sperm) antisera showed far fewer reactive antibody species than allogeneic immune sera. The anti-BALB/c sera recognized an antigen of 23 kDa in sperm extracts from DBA/2J and C57BL/6 mice, and failed to react with an antigen of the same molecular weight when applied to sperm from A/J and 129/J mice, indicating antigenic differences between sperm from these inbred strains. Anti-C57BL/6 sera contained a unique antibody which reacted with an antigen of 80 kDa in all of the 6 sperm extracts, whereas others antisera did not detect this antigen. These findings indicate antigenic and immunogenic polymorphism in sperm from different inbred strains of mice.

Carotid ligation alters cholecystokinin-8 (CCK-8) immunoreactivity in gerbil brains

The unilateral or bilateral carotid arteries were ligated in gerbils used as a model of cerebral ischemia. The effect of different times of bilateral ischemia on the content of CCK-8 in fore regions of gerbil brain and the effect of 30 min of unilateral ischemia on the content of CCK-8 of the same regions in gerbils with or without neurological signs were observed. Our results show that the content of CCK-8 of cortex, basal ganglia, thalamus and hypothalamus decreased significantly. But, in brain stem it remained basically unchanged no matter whether the ischemia was unilateral or bilateral. This suggests that there is a close relationship between CCK-8 and cerebral ischemia, and raises the possibility that CCK-8 may be involved in cerebral ischemia through a yet unclear mechanism.

A cellular analysis of long-term haematopoietic damage in mice after repeated treatment with cyclophosphamide

Following repeated treatment of mice with cyclophosphamide (5 X 200 mg/kg) it was found that slight, but significant, residual marrow damage persisted for at least half the lifespan of the animals. This long-term damage occurred despite preferential sparing of those multi-potential haematopoietic cells (CFU-S) that had a high self-renewal capacity after each step of the multistep regimen and despite a smaller CFU-S kill after each successive dose. The damage was characterized by low mean numbers of CFU-S and stromal colony-forming cells (CFU-F) which were around 70% of control values. Examination of individual animals revealed that the majority had slightly subnormal numbers of CFU-S and CFU-F, with only a few suffering a more severe injury, including 8% of mice with clinical hypoplasia or myelodysplasia.

Analysis of products formed during bleomycin-mediated DNA degradation

By the use of DNA, copolymers of defined nucleotide composition, and a synthetic dodecanucleotide having putative bleomycin cleavage sites in proximity to the 5'- and 3'-termini, the products formed concomitant with DNA strand scission have been isolated and subjected to structural identification and quantitation via direct comparison with authentic synthetic samples. The products of DNA strand scission by Fe(II)-bleomycin include oligonucleotides having each of the four possible nucleoside 3'-(phosphoro-2''-O-glycolates) at their 3'-termini, as well as the four possible base propenals. At least for 3-(adenin-9'-yl)propenal and 3-(thymin-1'-yl)propenal, the products formed were exclusively of the trans configuration.