Hafnia alvei. Respiratory tract isolates in a community hospital over a three-year period and a literature review

In a retrospective review, a group of seven patients were found to have a sputum culture positive for Hafnia alvei. Hafnia alvei is a Gram-negative enteric and oropharyngeal bacillus and usually is nonpathogenic. All our patients had a chronic underlying illness and one of the patients was endotracheally intubated at the time of the isolation of this organism. Six of seven patients had other organisms isolated along with H alvei, and only one patient had a pure growth of H alvei confirmed by a culture obtained from a bronchoscopic protected brush specimen. All isolates displayed resistance to conventional antibiotics including cephalosporins and penicillins. Although rare, H alvei may be a potential pathogen in a patient with a chronic underlying illness.

A survey of actinic keratoses among paraquat production workers and a nonexposed friend reference group

Follow-up on two reports of an excess of keratoses among paraquat production workers was conducted to evaluate the contribution of occupational exposures to the prevalence of keratoses among workers in a paraquat production plant in Texas. A cross-sectional study design was used to compare the prevalence of keratoses among current workers to an age, race, and sex frequency-matched group of their friends who had never worked at the plant. The analysis is based on 112 workers and 232 friends. Exposure, outcome, and covariables used in the analyses were obtained from an interview questionnaire, dermatology exam, and company records. Overall, the prevalence proportion of the presence of any actinic keratoses among workers and friends was similar (0.30 and 0.28, respectively). Among high cumulative exposed workers, the prevalence of any actinic keratoses was 0.40 compared to 0.20 among low-exposed workers and 0.28 among friends. These results were further explored using a multiple logistic regression approach to adjust for known risk and possibly confounding variables. Statistically significant high risks of actinic keratoses were demonstrated for freckling before age 16 years, older age, suntanning behaviors, occupational exposure to polycyclic aromatic hydrocarbons (PAH), and Fitzpatrick skin type. There was no significant contribution of overall exposure status (worker vs. friend). Similar to the crude analysis, the odds of actinic keratoses of high-exposed workers compared to friends was 1.9 (confidence interval [CI] = 0.9-4.2) whereas the comparable odds ratio for low-exposed workers vs. friends was 0.6 (CI = 0.2-1.7). These data do not demonstrate an excess of actinic keratoses overall nor any consistent increase in the odds of keratoses with an increase in plant exposure level.

Micturition patterns after spinal trauma as a measure of autonomic functional recovery

The purpose of these experiments was to determine whether experimental spinal trauma would result in urological dysfunction similar to that seen clinically and whether recovery of normal micturition can be correlated with motor functional recovery. A standard rat model of spinal impact trauma was employed. Neurologic evaluation included a modified 7 point hindlimb Tarlov scale applied weekly for 4 weeks after injury. Micturition measurement was accomplished by placing the animal in a metabolic cage for 24-hour periods and collecting urine on an electronic scale connected to Lotus Measure data acquisition software. All assessments were performed in a blinded fashion. Animals were categorized as normal control (N = 10), sham injured (N = 11), spinal cord injury (SCI) without (N = 11) and with locomotor recovery (N = 11). There were no differences in total micturition volume among the 4 groups, while the number of micturitions per 24 hours was significantly less for SCI without locomotor recovery (10.4 +/- 5.9) than for control (21.3 +/- 4.5). The volume per micturition was significantly greater for SCI (2.0 +/- 0.7 ml.) than for control (0.8 +/- 0.2 ml.). There were no differences among groups in the ratio of number of micturitions night/day. The SCI group had significantly greater largest and smallest micturitional volumes. Results clearly show alterations in micturition patterns induced by SCI. These were proportional to, but did not correlate fully with, the severity of injury and degree of motor recovery. Thus, recovery of a normal micturition pattern did not occur to the same extent as did motor functional recovery. This difference underscores the potential value of autonomic measures of SCI for distinguishing outcome categories after experimental SCI.

Molecular cloning and centrosomal localization of human caltractin

Caltractin, a 20-kDa calcium-binding protein, was previously purified and cloned at the DNA level from the unicellular green alga Chlamydomonas. It is a structural component of the basal body complex, the major microtubule-organizing center in Chlamydomonas and the functional homolog of the centrosome in the animal cell. Here we report the characterization of a cDNA encoding a human caltractin that shares a high degree of amino acid identity (70%) with its algal counterpart. Caltractin was identified in both HeLa and BHK cells as a 21-kDa polypeptide specifically localized to the centrosome of interphase and mitotic cells. The high level of conservation in the amino acid sequence of caltractin from algae to humans and its association with the major microtubule-organizing center in the cell suggest that caltractin plays a fundamental role in microtubule-organizing center structure and function.

Effects of rhynchophylline on motor activity of mice and serotonin and dopamine in rat brain

Rhynchophylline (Rhy) reduced the spontaneous motor activity and enhanced the sedative and hypnotic effects of sodium pentobarbital in mice. The effects of Rhy on serotonin (5-HT) and dopamine (DA) concentrations in rat brain, and the release of 5-HT and DA from the regional brain slices were studied by a fluorescence detector. Rhy increased the 5-HT content in the hypothalamus and cortex, but reduced the DA concentrations in the cortex, amygdala, and spinal cord. Rhy promoted the release of endogenous DA from 4 brain regions. The release of 5-HT was increased in 2 brain regions and decreased in hypothalamus slice. However, Rhy inhibited the release of both 5-HT and DA evoked by high potassium.

Crystal structure of the Y52F/Y73F double mutant of phospholipase A2: increased hydrophobic interactions of the phenyl groups compensate for the disrupted hydrogen bonds of the tyrosines

The enzyme phospholipase A2 (PLA2) catalyzes the hydrolysis of the sn-2 ester bond of membrane phospholipids. The highly conserved Tyr residues 52 and 73 in the enzyme form hydrogen bonds to the carboxylate group of the catalytic Asp-99. These hydrogen bonds were initially regarded as essential for the interfacial recognition and the stability of the overall catalytic network. The elimination of the hydrogen bonds involving the phenolic hydroxyl groups of the Tyr-52 and -73 by changing them to Phe lowered the stability but did not significantly affect the catalytic activity of the enzyme. The X-ray crystal structure of the double mutant Y52F/Y73F has been determined at 1.93 A resolution to study the effect of the mutation on the structure. The crystals are trigonal, space group P3(1)21, with cell parameters a = b = 46.3 A and c = 102.95 A. Intensity data were collected on a Siemens area detector, 8,024 reflections were unique with an R(sym) of 4.5% out of a total of 27,203. The structure was refined using all the unique reflections by XPLOR to a final R-factor of 18.6% for 955 protein atoms, 91 water molecules, and 1 calcium ion. The root mean square deviation for the alpha-carbon atoms between the double mutant and wild type was 0.56 A. The crystal structure revealed that four hydrogen bonds were lost in the catalytic network; three involving the tyrosines and one involving Pro-68. However, the hydrogen bonds of the catalytic triad, His-48, Asp-99, and the catalytic water, are retained. There is no additional solvent molecule at the active site to replace the missing hydroxyl groups; instead, the replacement of the phenolic OH groups by H atoms draws the Phe residues closer to the neighboring residues compared to wild type; Phe-52 moves toward His-48 and Asp-99 of the catalytic diad, and Phe-73 moves toward Met-8, both by about 0.5 A. The closing of the voids left by the OH groups increases the hydrophobic interactions compensating for the lost hydrogen bonds. The conservation of the triad hydrogen bonds and the stabilization of the active site by the increased hydrophobic interactions could explain why the double mutant has activity similar to wild type. The results indicate that the aspartyl carboxylate group of the catalytic triad can function alone without additional support from the hydrogen bonds of the two Tyr residues.

Light-evoked expansion of subretinal space volume in the retina of the frog

The retina of the frog was superfused with a Ringer solution containing impermeant "probe" cations and anions. Light-evoked concentration changes in these probe ions were measured in the subretinal space (SRS) with ion-selective microelectrodes. A decrease in probe ion concentration was found, and several observations suggest that this is caused by a light-evoked expansion of the SRS. The probe ion decrease was not seen in the isolated retina; thus, the pigment epithelial (PE) cells are important for its generation. Pharmacological studies suggest that K+ channels in the PE cells are important--perhaps the PE cells shrink in response to the light-evoked decrease in SRS [K+]. The light-evoked decrease of SRS volume may be important in the understanding of SRS solute concentrations, retina-PE adhesivity, photoreceptor-PE cell interactions, and the interphotoreceptor matrix.

Embryogenesis and plant regeneration from isolated microspores of Brassica rapa L. ssp. Oleifera

Conditions favourable to embryogenesis from isolated microspores of Brassica rapa L. ssp. oleifera (canola quality) were identified. A population with enhanced responsiveness for microspore embryogenesis (C200) was synthesized by crossing individual plants showing microspore embryogenic potential. For optimal microspore embryogenesis, buds (2-3mm in length, containing mid-late uninucieate microspores) were collected from older plants (2 months old) and microspores isolated and washed in iron-free B5 medium. NLN medium with its iron content reduced to half was beneficial for initial microspore culture. An elevated temperature(33-35°C) during the first day of culture, followed by maintenance at 25°C resulted in dozens of embryos from each isolation (about 100 buds). Seeds were obtained from plants regenerated from microsporederived embryos after colchicine treatment.

Insulin and insulinlike growth factors in embryonic development. Effects of a biologically inert insulin (guinea pig) on rat embryonic growth and development in vitro

Congenital anomalies occur up to four times more frequently in diabetic pregnancy than in the nondiabetic population. Although past work has shown that maternal hyperglycemia and hyperketonemia may increase embryonic abnormalities, recent experimental evidence suggests that low insulin levels may also contribute to diabetic embryopathy. This study investigated the effects of guinea pig serum (whose insulin is inactive in rat systems) on rat embryonic growth and development in culture. Supplementation of guinea pig serum with pork insulin at low (1 ng/ml) and high (5 ng/ml) physiological concentrations and insulinlike growth factors (IGF) I and II were also studied. Culture of rat embryos from the early headfold stage in guinea pig serum resulted in poor embryonic growth and development with a 92% rate of anomalies. Supplementation of guinea pig serum with zinc-binding pork insulin significantly improved rat embryonic growth and development (46% anomaly rate) especially between the first 5 and 21 h of the period of organogenesis. This evidence supports our most recent findings that low insulin levels, as encountered in untreated diabetic pregnancy, may contribute to the increased risk of congenital abnormality. Insulin at low physiological concentrations improved growth, whereas higher physiological concentrations were required to increase growth and development. IGF-I or IGF-II supplementation improved rat embryonic growth and development but failed to match that of the controls, indicating that other growth factors including insulin may also be required.

Evaluation of transgenic canola plants under field conditions

Eleven independent transgenic canola (Brassica napus ssp. oleifera L. cv. Westar and Regent) lines were evaluated in the field. The plants carried a neomycin phosphotransferase (NPTII) gene for kanamycin resistance that was introduced via Agrobacterium-mediated transformation. NPTII enzyme assays, Southern blot by hybridizations and progeny analysis, confirmed the stable, heritable integration and expression of the introduced NPTII gene. A number of agronomic characteristics evaluated under field conditions, including maturity yield, and oil and protein content, were all statistically comparable between the transformed and nontransforemd platns. These results indicate that canola can be genetically engineered successfully, and that the Agrobacterium-based transformation system employed does not induced any adverse effects on the intrinsic agronomic and qualitative traits critical to the agricultural industry.

Cellular reaction to the Vascugraft polyesterurethane vascular prosthesis: in vivo studies in rats

The biocompatibility of Vascugraft, a polyesterurethane vascular prosthesis manufactured by Braun-Melsungen AG, was assessed by immunofluorescence and histological studies. Discs, 1 cm2, of Vascugraft prosthesis were implanted into the peritoneal cavity of rats. Results were compared with Impra, GORE-TEX and Mitrathane prostheses and a control group. Animals were killed at 1, 2, 6, 9 and 12 wk. Total T cells, T helper cells, T suppressor cells and activated T lymphocytes expressing Interleukin-2 receptors were quantified by a cytofluorometric technique in the peripheral blood of rats. For each period of implantation, all vascular prostheses showed no significant change in the percentage of total T cells, T subsets and T cells expressing Interleukin-2 receptors when compared to the control group. Histological examination of the tissue reaction surrounding the Vascugraft revealed a mild inflammatory reaction, similar to the one observed with both polytetrafluoroethylene grafts. However, the rate and the degree of encapsulation were different between grafts. The Vascugraft prosthesis was well encapsulated 2 wk after implantation, whereas inhibition of fibroblastic proliferation into the graft wall and surrounding both polytetrafluoroethylene grafts was observed for each period of implantation. The Mitrathane prosthesis exhibited a moderate inflammatory response, characterized by a high level of activation on fibroblasts compared to other grafts.

Genomic structure of Chlamydomonas caltractin. Evidence for intron insertion suggests a probable genealogy for the EF-hand superfamily of proteins

A clone containing the gene locus for Chlamydomonas caltractin, a 20,000 Mr calcium-binding protein that is a member of the EF-hand superfamily of calcium-modulated proteins, was isolated and the structural organization of the gene was determined. The intron-exon organization was resolved by direct comparison of the genomic sequence with a caltractin cDNA. The promoter region does not contain the typical TATA or CCAAT boxes, but the sequences at the splice junctions are similar to those of other eukaryotes. The positions of the six introns in the caltractin gene do not typically define unit structures, nor do they coincide with those in genes for other members of the EF-hand superfamily. An analysis of exon sequences at the splice junctions in the genes of this multigene family was undertaken; evidence was obtained that supports the hypothesis that introns arose at proto-splice sites. A probable evolutionary history for the EF-hand superfamily based on intron insertion is offered.

Comparison of pharmacological agents (aspartate vs. aminophosphonobutyric plus kynurenic acids) to block synaptic transmission from retinal photoreceptors in frog

The combination of aminophosphonobutyric plus kynurenic acids (APB/Kyn) was compared to aspartate with respect to its ability to block synaptic transmission from photoreceptors. Like aspartate, APB/Kyn blocks photoreceptor synaptic transmission, as monitored by the b- and d-waves of the electroretinogram, by the proximal negative response and M-wave of the proximal retina, and by the light-evoked increase in extracellular K+ concentration in the inner plexiform layer. Unlike aspartate, APB/Kyn has relatively minor effects on retinal resistance, light-evoked changes in K+ and Ca2+ concentrations in the subretinal space, light-evoked changes in subretinal space volume, resting extracellular concentrations of K+ and Ca2+ in the proximal and distal retina, and the c-wave. Effects of APB/Kyn are generally more reversible than effects of Asp. A disadvantage of APB/Kyn is that the a-wave usually becomes smaller and slower. Overall, APB/Kyn disrupts the retina less than aspartate. Therefore, in some situations in which blockade of photoreceptor synaptic transmission is desired, the use of APB/Kyn may be preferable to that of aspartate.

The colR4 and colR15 beta-tubulin mutations in Chlamydomonas reinhardtii confer altered sensitivities to microtubule inhibitors and herbicides by enhancing microtubule stability

The colR4 and colR15 beta 2-tubulin missense mutations for lysine-350 in Chlamydomonas reinhardtii (Lee and Huang, 1990) were originally isolated by selection for resistance to the growth inhibitory effects of colchicine. The colR4 and colR15 mutants have been found to be cross resistant to vinblastine and several classes of antimitotic herbicides, including the dinitroanilines (oryzalin, trifluralin, profluralin, and ethafluralin); the phosphoric amide amiprophos methyl; and the dimethyl propynl benzamide pronamide. Like colchicine and vinblastine, the antimitotic effects of these plant-specific herbicides have been associated with the depolymerization of microtubules. In contrast to their resistance to microtubule-depolymerizing drugs, the mutants have an increased sensitivity to taxol, a drug which enhances the polymerization and stability of microtubules. This pattern of altered sensitivity to different microtubule inhibitors was found to cosegregate and corevert with the beta-tubulin mutations providing the first genetic evidence that the in vivo herbicidal effects of the dinitroanilines, amiprophos methyl, and pronamide are related to microtubule function. Although wild-type like in their growth characteristics, the colR4 and colR15 mutants were found to have an altered pattern of microtubules containing acetylated alpha-tubulin, a posttranslational modification that has been associated with stable subsets of microtubules found in a variety of cells. Microtubules in the interphase cytoplasm and those of the intranuclear spindle of mitotic cells, which in wild-type Chlamydomonas cells do not contain acetylated alpha-tubulin, were found to be acetylated in the mutants. These data taken together suggest that the colR4 and colR15 missense mutations increase the stability of the microtubules into which the mutant beta-tubulins are incorporated and that the altered drug sensitivities of the mutants are a consequence of this enhanced microtubule stability.

Missense mutations at lysine 350 in beta 2-tubulin confer altered sensitivity to microtubule inhibitors in Chlamydomonas

Two beta-tubulin mutants of Chlamydomonas reinhardtii, colR4 and colR15, were previously isolated in our laboratory. Each mutant expressed an acidic beta-tubulin variant as a result of an alteration in the coding sequence of one of the two beta-tubulin genes in C. reinhardtii, which in the wild type encode identical proteins. In this report, we describe the identity of the specific beta-tubulin altered in the colR mutants and the precise nature of the genetic lesions. Hybrid selection of mutant poly(A)+ RNA with cDNA probes specific for the two beta-tubulins in C. reinhardtii indicated that both mutations resided in the beta 2-tubulin gene. cDNA libraries were constructed with mutant poly(A)+ RNA, and beta 2-tubulin cDNA clones were isolated. Results of in vitro transcription of cloned beta 2-tubulin cDNAs confirmed the identity of the altered genes. Sequencing of the entire coding regions of the beta 2-tubulin cDNA clones revealed that the mutants carried different single-base substitutions in the same codon for the amino acid at position 350 in the beta 2-tubulin sequence, effecting a change from a lysine to a glutamic acid in the colR4 variant and to a methionine in the colR15 variant. These changes in amino acids are consistent with the difference in the charge of the two variant polypeptides observed in isoelectric focusing. Because both the colR4 and colR15 mutations confer an altered sensitivity to a number of different microtubule inhibitors and herbicides, lysine 350 appears to be of functional importance in the structure of the tubulin molecule.

Effects of culture density, conditioned medium and feeder cultures on microspore embryogenesis in Brassica napus L. cv. Topas

In microspore cultures of Brassica napus L. cv. Topas, embryo yield increases with culture density up to about 40,000 microspores per ml. A much higher density (100,000 per ml) appears inhibitory to embryogenesis. A relatively high culture density (30,000 or 40,000 per ml) for the first 2-4 days of culture is crucial for embryogenesis, after which cultures may be diluted to allow better embryo growth.Medium conditioned by culturing microspores at 30,000 or 40,000 per ml for 1 day improved microspore-embryo yield in low density cultures (3,000 or 4,000 per ml) more than 3-fold. In contrast, media conditioned with microspores from 1-4 days or 0-4 days of culture were inhibitory.Use of feeder cultures resulted in up to 10-fold increase of embryo yield in low density microspore cultures, depending on the method used. Filter papers and other membranes placed on top of feeders greatly inhibited embryogenesis in the feeder layer as well as microspores cultured on the feeder, possibly due to poorer gaseous exchange.

Light-evoked changes in extracellular calcium concentration in frog retina

Light-evoked changes in extracellular Ca2+ concentration were recorded with Ca2(+)-selective microelectrodes in the retina of the frog eyecup. A Ca-decrease at light onset and offset was found in the inner plexiform layer, and its properties are consistent with it resulting from Ca2+ influx into activated neuronal terminals. In the subretinal space, a Ca-increase at light onset and a Ca-decrease at offset were observed, and these likely arise directly from photoreceptors. A slower ON Ca-decrease was also seen here. Because it survives pharmacological isolation of the photoreceptors from post-synaptic interactions, but not physical isolation of the retina from the pigment epithelium, this component probably depends on pigment epithelial activity.

Molecular cloning and characterization of senescence-related genes from carnation flower petals

The senescence of carnation (Dianthus caryophyllus L.) flower petals is associated with increased production of ethylene which plays an important role in regulating this developmental event. Three senescence-related cDNA clones were isolated from a cDNA library prepared from mRNA isolated from senescing petals. These cDNAs are representative of two classes of mRNAs which increase in abundance in senescing petal tissue. The mRNA for one class is present at low levels during the early stages of development and begins to accumulate in mature petals prior to the increase in ethylene production. The accumulation of this mRNA is reduced, but not eliminated, in petals treated with aminooxyacetic acid, an inhibitor of ethylene biosynthesis, or silver thiosulfate, an ethylene action inhibitor. In contrast, expression of the second class of mRNAs appears to be highly regulated by ethylene. These mRNAs are not detectable prior to the rise in ethylene production and increase in abundance in parallel with the ethylene climacteric. Furthermore, expression of these mRNAs is significantly inhibited by both aminooxyacetic acid and silver thiosulfate. Expression of these mRNAs in vegetative and floral organs was limited to floral tissue, and predominantly to senescing petals.

Current-evoked transcellular K+ flux in frog retina

1. Changes in extracellular K+ concentration (delta[K+]o) evoked by electrical current were measured with K+-selective microelectrodes (K-ISMs) in the retina of the frog eyecup. 2. In the superfusate at 20 microns above the inner limiting membrane (ILM), current-evoked delta[K+] was a function of current polarity and strength; its amplitude decreased as the K-ISM was moved higher above the ILM. Responses were similar whether measured with K-ISMs containing the Corning exchanger or a valinomycin-based liquid membrane. No current-evoked delta[Ca2+] could be detected with Ca-selective microelectrodes (Ca-ISMs). 3. Within the retina, a complex spatiotemporal profile of current-evoked delta[K+]o was observed. Strophanthidin abolished responses in the proximal retina, but had little effect on the response in the superfusate. A blocker of K+ channels (Ba2+) depressed responses in the superfusate, but not in the proximal retina. 4. Quantitative analysis of these responses indicates a transport number for K+ of 0.18 at onset of current, and that decreases over a few seconds. In contrast, a transport number of approximately 0.01 is predicted from the expected ionic concentrations within extracellular space. 5. These findings are compatible with the delta[K+] above the ILM being due to transcellular movement of K+ through Müller cells. The results suggest that K+ spatial buffering may be particularly potent in the retina. Furthermore, determinations of tissue characteristics by passage of electrical current must take into account that at least 17% of the current does not travel through extracellular space.

Purification and characterization of a basal body-associated Ca2+-binding protein

Isolated basal body complexes from the unicellular alga, Chlamydomonas reinhardtii were found to contain a low molecular mass acidic polypeptide, distinct from calmodulin, but with biochemical features in common with members of the calmodulin family of calcium-binding proteins. These common characteristics included a relative low molecular mass of 20 kD, an experimentally determined acidic pI of 5.3, an altered electrophoretic mobility in SDS-polyacrylamide gels in the presence of added calcium, and a calcium-dependent binding to the hydrophobic ligand phenyl-Sepharose which allowed its purification by affinity chromatography. The relatedness of the basal body-associated 20-kD calcium-binding protein (CaBP) to calmodulin was confirmed by amino acid compositional analysis and partial peptide sequencing of the isolated protein. A rabbit antibody specific for the 20-kD CaBP was raised and used to determine by indirect immunofluorescence the cellular localization of the protein in Chlamydomonas cells. In interphase cells the antibody stained intensely the region between the paired basal bodies, two fibers extending between the basal bodies and the underlying nucleus, and an array of longitudinal filaments surrounding the nucleus. The two basal body-nuclear connecting fibers were identified in thin-section electron micrographs to be narrow striated fiber roots. In mitotic cells the 20-kD CaBP was specifically associated with the poles of the mitotic spindle at the sites of the duplicated basal body complexes.

Molecular cloning of cDNA for caltractin, a basal body-associated Ca2+-binding protein: homology in its protein sequence with calmodulin and the yeast CDC31 gene product

An extended synthetic oligonucleotide (59-mer) was used to isolate a Chlamydomonas cDNA containing the entire coding region for a novel basal body-associated 20-kD calcium-binding protein (CaBP). DNA and RNA blot analysis indicate that the 20-kD CaBP is encoded by a single copy gene from which is derived an approximately 1.1-kb-long transcript. The deduced amino acid sequence for the protein shows a linear relatedness with calmodulin from Chlamydomonas and other organisms (45-48% identity). The primary protein sequence of the 20-kD CaBP and its predicted secondary structure suggests that the protein is likely to contain four homologous calcium-binding domains that conform to the helix-loop-helix (or EF hand) structure found in calmodulin and related calcium-modulated proteins. The major difference between the protein and calmodulin is an amino-terminal domain of 21 amino acids present on the 20-kD CaBP. In addition to its relatedness to calmodulin, the Chlamydomonas 20-kD CaBP shows a strong sequence identity (50%) with the yeast Saccharomyces cerevisiae CDC31 gene product required for spindle pole body duplication. The association of these sequence-related calcium-binding proteins to microtubule-organizing centers of divergent structure suggests a potential conserved function for the proteins.

Cadmium tolerance in tobacco cell culture and its relevance to temperature stress

Growth of unselected tobacco (Nicotiana tabacum W38) cell suspension cultures was reduced by 50-200 μM cadmium (Cd) in the culture medium and cells were killed by 400 μM Cd. Tolerance to Cd was increased either by using rapidly growing cells or by culturing cells at higher densities. Cell lines tolerant to 2 mM Cd were established by progressively elevating levels of Cd in the culture medium. The Cd tolerance was not due to differences in uptake between unselected and Cd-tolerant cell lines, and the tolerance to Cd was not lost during long term culture in the absence of Cd. Cd-tolerant cells also showed higher tolerance to heat shock (37.5°C, 2-8 hours) and cold treatments (4°C, 1-7 days) than the unselected cells.

Beta-tubulin mutants of the unicellular green alga Chlamydomonas reinhardtii

Two beta-tubulin mutants of the unicellular green alga Chlamydomonas reinhardtii have been isolated on the basis of altered sensitivity to the growth-inhibitory effect of colchicine. The two mutations of colR4 and colR15 have been found to be tightly linked, mapping to a previously unmarked site in linkage group XII. The drug-resistance phenotypes of both mutations segregated in genetic crosses with the presence of distinct, acidic variant beta-tubulin isoforms found assembled into the microtubules of the flagella. Analysis of the in vitro translation products of total poly(A)+ RNA from the mutants provided evidence that the variant proteins are altered primary beta-tubulin gene products. Compared to wild type, strains carrying the mutations expressed an increased resistance to the inhibitory effects of colchicine in clonal growth, flagellar assembly, and germination of meiotic products, suggesting that the beta-tubulin altered in the mutants participates in multiple microtubule functions.

Phytochelatin synthesis and glutathione levels in response to heavy metals in tomato cells

Cell suspension cultures of tomato, Lycopersicon esculentum Mill. cv VFNT-Cherry, produce phytochelatins (poly[gamma-glutamylcysteinyl]glycines) when exposed to cadmium. The synthesis of these peptides is accompanied by a decline in cellular levels of glutathione. Buthionine sulfoximine, an inhibitor of glutathione synthesis, inhibits the sustained production of phytochelatins. However, phytochelatin synthesis can occur in the presence of buthionine sulfoximine provided that sufficient glutathione is available. These results indicate that glutathione is a substrate for phytochelatin synthesis. The protein synthesis inhibitor cycloheximide does not affect the initial production of phytochelatin.

Single intravenous dose and steady-state oral dose pharmacokinetics of nicardipine in healthy subjects

Nicardipine HCl oral doses (10-40 mg) were administered sequentially to six healthy subjects. For each regimen the capsule dose was administered every 8 hours (q 8 h) for 3 days and the plasma profiles of nicardipine and its pyridine analogue (M5) were determined following the last dose on day 4. Steady-state plasma concentrations of nicardipine for each subject were fitted very well by the Michaelis-Menten equation. An intravenous tracer dose (0.885 mg nicardipine HCl) was administered simultaneously with the final oral dose on the fourth day of the 30 mg q 8 h regimen. The steady-state bioavailability of nicardipine was shown to be dose-dependent and averaged 19 per cent (10 mg), 22 per cent (20 mg), 28 per cent (30 mg), and 38 per cent (40 mg). Nicardipine undergoes linear first-pass metabolism to M5. Other metabolic pathways are responsible for the saturable first-pass metabolism observed for nicardipine.

Combinational diversity within variable regions bearing the predominant anti-p-azophenylarsonate idiotype of strain A mice

The humoral immune response in strain A mice to protein conjugates of p-azophenylarsonate (Ars) is characterized by the presence of a major cross-reactive idiotype denoted as IdCR. Previous molecular analyses of monoclonal IdCR+ Ars-binding antibodies isolated from multiply immunized animals have indicated that these antibody variable (V) regions may be the expressed product of a single combination of VH, D, JH, V kappa, and J kappa gene segments. The basis of this apparent domination of the Ars response by V regions encoded by this single combination of gene segments is unclear, but is discussed in this report. Our structural analyses on five monoclonal IdCR+ antibodies that are unable to bind Ars show that in contrast to those of Ars-binding IdCR+ antibodies, these (Ars-nonbinding) IdCR+ V regions are encoded by multiple combinations of VH, D, JH, V kappa, and J kappa gene segments, but with the commonality that they all utilize a single VH gene segment (VHIdCR). We provide examples in which the VHIdCR gene segment is expressed with three different V kappa gene segments and with each of the four JH gene segments to produce serologically detectable IdCR+ Ars-nonbinding antibodies. It would thus appear that the previous failure to detect alternative IdCR+ V segment combinations was due to a sampling procedure requiring that the IdCR+ antibody bind Ars, and not the result of restricted assembly or expression of the VHIdCR gene segment with a particular combination of D, JH, V kappa, and J kappa gene segments. This bias in protocol, however, cannot completely account for the homogeneity in previously studied IdCR+ Ars-binding antibodies, because we were able to isolate, from primary immune responses, IdCR+ antibodies that do bind Ars but that utilize alternative V segment combinations. This finding suggests that combinations of V gene segments encoding IdCR+ antibodies are more numerous in primary as opposed to secondary immune responses, and raises the question of why a single combination of VH, D, JH, V kappa, and J kappa gene segments dominates the secondary strain A immune response to Ars.

Combinational diversity within variable regions bearing the predominant anti-p-azophenylarsonate idiotype of strain A mice

The humoral immune response in strain A mice to protein conjugates of p-azophenylarsonate (Ars) is characterized by the presence of a major cross-reactive idiotype denoted as IdCR. Previous molecular analyses of monoclonal IdCR+ Ars-binding antibodies isolated from multiply immunized animals have indicated that these antibody variable (V) regions may be the expressed product of a single combination of VH, D, JH, V kappa, and J kappa gene segments. The basis of this apparent domination of the Ars response by V regions encoded by this single combination of gene segments is unclear, but is discussed in this report. Our structural analyses on five monoclonal IdCR+ antibodies that are unable to bind Ars show that in contrast to those of Ars-binding IdCR+ antibodies, these (Ars-nonbinding) IdCR+ V regions are encoded by multiple combinations of VH, D, JH, V kappa, and J kappa gene segments, but with the commonality that they all utilize a single VH gene segment (VHIdCR). We provide examples in which the VHIdCR gene segment is expressed with three different V kappa gene segments and with each of the four JH gene segments to produce serologically detectable IdCR+ Ars-nonbinding antibodies. It would thus appear that the previous failure to detect alternative IdCR+ V segment combinations was due to a sampling procedure requiring that the IdCR+ antibody bind Ars, and not the result of restricted assembly or expression of the VHIdCR gene segment with a particular combination of D, JH, V kappa, and J kappa gene segments. This bias in protocol, however, cannot completely account for the homogeneity in previously studied IdCR+ Ars-binding antibodies, because we were able to isolate, from primary immune responses, IdCR+ antibodies that do bind Ars but that utilize alternative V segment combinations. This finding suggests that combinations of V gene segments encoding IdCR+ antibodies are more numerous in primary as opposed to secondary immune responses, and raises the question of why a single combination of VH, D, JH, V kappa, and J kappa gene segments dominates the secondary strain A immune response to Ars.

Mutant strains of Chlamydomonas reinhardtii that move backwards only

Mutations at three independent loci in Chlamydomonas reinhardtii result in a striking alteration of cell motility. Mutant cells representing the three mbo loci move backwards only, propelled by a symmetrical "flagellar" type of bending pattern. The characteristic asymmetric "ciliary" type of flagellar bend pattern responsible for forward movement that predominates in wild-type cells is seldom seen in the mutants. This defect in motility was found to be a property of the mutant axonemes themselves: the isolated axonemes, reactivated by addition of ATP, showed exclusively the symmetrical wave form, and the protein composition of these axonemes differed from the wild-type composition. Axonemes obtained from mbo1 , mbo2 , and mbo3 cells were found to be deficient in six polypeptides regularly present in wild type. The mbo2 axonemes were deficient in two additional polypeptides. The polypeptides were identified in autoradiograms of two-dimensional SDS polyacrylamide gel electrophoretograms of 35S- or 32P-labeled axonemes. One of the six polypeptides has previously been identified; it is a component missing in a mutant deficient for inner dynein arms. Of the five axonemal polypeptides newly identified by the mbo mutants, four were shown to be present as phosphoproteins in wild-type axonemes. One of the additional polypeptides deficient in mbo2 axonemes was also shown to be phosphorylated in wild-type axonemes. Detailed ultrastructural analysis of the mbo1 flagella and the mbo1 , mbo2A , and mbo3 axonemes revealed that the mutants specifically lack the beak-like projections found within the B-tubules of outer doublets 5 and 6.

Surgical management for recurrent pharyngoesophageal (Zenker's) diverticulum

Recurrent pharyngoesophageal diverticulum is uncommon after a one-stage diverticulectomy. Among 888 operations at the Mayo Clinic, recurrence has been noted after only 32 (3.6%). The present report outlines our management during a 19-year period of 44 patients operated on previously, including management of various late complications seen in 13 patients after diverticulopexy and diverticulectomy performed at other institutions. The study then focuses on the results in 31 patients in whom reoperation for symptomatic recurrent diverticulum was performed at the Mayo Clinic during the same period. Although reoperation posed a technical challenge, there was only 1 operative death (3.2%). Surviving patients experienced highly satisfactory late results, with only two recurrences. Early surgical morbidity was considerably higher than for primary operations, but this did not interfere with most patients having excellent to good late results.

Genetic dissection of the central pair microtubules of the flagella of Chlamydomonas reinhardtii

Mutations at two loci, which cause an altered mobility of the flagella, affected the central pair microtubule complex of Chlamydomonas reinhardtii flagella. The mutations at both loci primarily affected the C1 microtubule of the complex. Three alleles at the PF16 locus affected the stability of the C1 microtubule in isolated axonemes. This phenotype has allowed us to determine that at least ten polypeptides of the central pair complex are unique to the C1 microtubule. The motility defect was correlated with the failure to assemble three of these ten polypeptides in vivo. The structural gene product of the PF16 locus was a polypeptide with molecular weight 57,000 as shown by analysis of five intragenic revertants and by analysis of axonemes from dikaryon rescue experiments. Three alleles at the PF6 locus affected the assembly of one of the two projections of the C1 microtubule and this projection was formed by at least three polypeptide components, which are a subset of polypeptides missing in isolated pf16 axonemes. No structural gene product has been identified for the PF6 locus. The gene product is probably not one of the identified projection constituents as shown by analysis of dikaryon rescue experiments. Chemical extraction of isolated wild-type axonemes suggests that at least seven polypeptide components are unique to the C2 microtubule.

Uniflagellar mutants of Chlamydomonas: evidence for the role of basal bodies in transmission of positional information

A series of uniflagellar mutants isolated following mutagenesis of Chlamydomonas reinhardtii (strain 137c) with ICR-191 show a remarkable positional phenotype. The flagellum that fails to develop is cis to the eyespot in more than 95% of the cells examined. Both the positional and the uniflagellar phenotypes are transmitted stably through mitotic and meiotic divisions, and in backcrosses the meiotic segregation is two mutant to two wild-type progeny. Four of the mutants, uni1, uni2, uni3 and uni4, have been studied extensively. They appear to be alleles of a single gene locus or to be closely linked (less than or equal to 0.06 map units). The characteristic expression of the uniflagellar defect in cells under different growth conditions or in stable diploids indicates that the mutations alter the rate of development of the flagellum in the cis-eyespot flagellum. Electron microscopic studies suggest that the developmental defect resides in the basal body. Extensive recombination analysis to 33 nuclear markers representing the 16 linkage groups failed to establish linkage. The uni mutants, however, showed linkage to four unmapped mutant loci. Mutations for each of these loci also affect flagellar assembly.

TEMPERATURE-SENSITIVE, ASSEMBLY-DEFECTIVE FLAGELLA MUTANTS OF CHLAMYDOMONAS REINHARDTII

We describe an efficient selection procedure for the isolation of mutants of Chlamydomonas reinhardtii with temperature sensitive flagella defects, with final yields of up to 11% of the population being mutant. Several mutants, all showing an inability to maintain flagellar integrity at the restrictive temperature, are described. We have examined flagellar stability and reassembly at various temperatures in the mutants. Mapping data are provided for these, as well as for some previously described mutants.

Analysis of the movement of Chlamydomonas flagella:" the function of the radial-spoke system is revealed by comparison of wild-type and mutant flagella

The mutation uni-1 gives rise to uniflagellate Chlamydomonas cells which rotate around a fixed point in the microscope field, so that the flagellar bending pattern can be photographed easily. This has allowed us to make a detailed analysis of the wild-type flagellar bending pattern and the bending patterns of flagella on several mutant strains. Cells containing uni-1, and recombinants of uni-1 with the suppressor mutations, suppf-1 and suppf-3, show the typical asymmetric bending pattern associated with forward swimming in Chlamydomonas, although suppf-1 flagella have about one-half the normal beta frequency, apparently as the result of defective function of the outer dynein arms. The pf-17 mutation has been shown to produce nonmotile flagella in which radial spoke heads and five characteristic axonemal polypeptides are missing. Recombinants containing pf-17 and either suppf-2 or suppf-3 have motile flagella, but still lack radial-spoke heads and the associated polypeptides. The flagellar bending pattern of these recombinants lacking radial-spoke heads is a nearly symmetric, large amplitude pattern which is quite unlike the wild-type pattern. However, the presence of an intact radial-spoke system is not required to convert active sliding into bending and is not required for bend initiation and bend propagation, since all of these processes are active in suppfpf-17 recombinants. The function of the radial-spoke system appears to be to convert the symmetric bending pattern displayed by these recombinants into the asymmetric bending pattern required for efficient swimming, by inhibiting the development of reverse bends during the recovery phase of the bending cycle.

Suppressor mutations in Chlamydomonas reveal a regulatory mechanism for Flagellar function

Reversion analysis of flagellar-motility mutants of Chlamydomonas reinhardtii yields an unusual class of intergenic suppressor mutations that restore flagellar activity to paralyzed radial-spoke or central-pair mutants without altering the structural or molecular defects associated with the original mutations. Four suppressors representing independent genetic loci were studied in detail. Two of the mutations, suppf1 and suppf2, restore flagellar motility to either radial-spoke or central-pair mutants of different genes. The mutants suppf3 and suppf 4 suppress flagellar paralysis associated only with mutants defective for the radial spokes. Analyses of the axonemal polypeptides of suppf1, suppf3 and suppf4 mutants indicate that the mutations restore flagellar activity to paralyzed radial-spoke or central-pair mutants by altering other components of the flagellar axoneme. suppf1 shows an altered electrophoretic migration for a 325,000 molecular weight polypeptide known to be a subunit of an outer-arm dynein. suppf3 and suppf4 are missing different axonemal polypeptides with molecular weights of 60,000 (in the case of suppf3), and 40,000 and 29,000 (in the case of suppf4). Genetic evidence has been obtained indicating that the polypeptides affected in suppf3 and suppf4 are components of a newly identified functional and/or structural compartment of the flagellar axoneme. The suppressor mutations described here reveal the operation of a control mechanism that inhibits the operations of flagellar movements in the presence of radial-spoke or central-pair defects. Suppressor mutations release the inhibition. The molecular defects of suppf1, suppf3 and suppf4 provide evidence that the inhibitory mechanism can be interrupted at two different levels of axonemal function.

Central-pair microtubular complex of Chlamydomonas flagella: polypeptide composition as revealed by analysis of mutants

Four mutants of Chlamydomonas reinhardtii representing independent gene loci have been shown to lack totally (pf-18, pf-19, and pf-15) or nearly totally (pf-20) the central microtubular pair complex in isolated axonemal preparations. Analysis of 35S-labeled axonemal proteins, using two methods of electrophoresis, reveals that all four mutants lack or are markedly deficient in 18 polypeptides, ranging in molecular weight from 360,000 to 20,000, that are regularly present in wild-type axonemes. Analyses of axonemal proteins labeled by cellular growth on 32P-labeled medium indicates that a subset of 8 of the 18 polypeptides are phosphorylated. Mutant and wild-type axonemes and flagella have been analyzed for their content of tubulin subunits using a high resolution two-dimensional electrophoresis system combined with agarose gel overlays containing either anti-alpha or anti-beta tubulin sera prepared from Chlamydomonas tubulins. The immunoprecipitates identify two major alpha tubulins, a major beta tubulin, and a minor component which is also precipitated by the anti-beta serum. None of these tubulins shows a specific defect in mutant axonemes, nor do the tubulin polypeptides show altered two-dimensional map positions in the mutant flagella. The 18 polypeptides provide a useful signature for identifying other mutants affecting the central-pair microtubular complex. Such mutants could be useful in defining the structural or functional role of these polypeptides in the central microtubules. Efforts to obtain additional central-pair mutants based on the motility phenotype of the four mutants analyzed here have yielded mutants which are allelic to three of the four mutants.

Radial spokes of Chlamydomonas flagella: genetic analysis of assembly and function

In addition to the previously studied pf-14 and pf-1 loci in Chlamydomonas reinhardtii, mutations for another five genes (pf-17, pf-24, pf-25, pf-26, and pf-27) have been identified and characterized as specifically affecting the assembly and function of the flagellar radial spokes. Mutants for each of the newly identified loci show selective alterations for one or more of the 17 polypeptides in the molecular weight range of 20,000-130,000 which form the radial spoke structure. In specific instances the molecular defect has been correlated with altered radial spoke morphology. Biochemical analysis of in vivo complementation in mutant X wild-type dikaryons has provided indirect evidence that mutations for four of the five new loci (pf-17, pf-24, pf-25, and pf-26) reside in structural genes for spoke components. In the case of pf-24, the identity of the mutant gene product was supported by analysis of induced intragenic revertants. In contrast to the other radial spoke mutants thus far investigated, evidence suggests that the gene product in pf-27 is extrinsic to the radial spokes and is required for the specific in vivo phosphorylation of spoke polypeptides.

Radial spokes of Chlamydomonas flagella: polypeptide composition and phosphorylation of stalk components

Polypeptides from flagella or axonemes of Chlamydomonas reinhardtii were analyzed by labeling cellular proteins by prolonged growth on 35S-containing media and using one- and two-dimensional electrophoretic techniques which can resolve greater than 170 axonemal components. By this approach, a paralyzed mutant that lacks axonemal radial spokes, pf14, has been shown to lack 17 polypeptides in the molecular weight range of 20,000 to 124,000 and in the isoelectric point range of 4.8-7.1. Five of those polypeptides are also missing in the mutant pf-1 which lacks only radial spokeheads. The identification of the 17 polypeptides missing in pf-14 as components of radial spoke structures and the localization of the polypeptides lacking in pf-1 within the spokehead, are supported by experiments of chemical dissection of wild-type axonemes. Extraction procedures that solubilize outer and inner dynein arms preserve the structure of the radial spokes along with the 17 polypeptides in question. Six radial spoke polypeptides are solubilized in conditions that cause disassembly of radial spokeheads from the stalks and those components include the five polypeptides missing in pf-1. No Ca++- or Mg++-activated ATPase activities were found to be associated with solubilized preparations of wild-type radial spokeheads. In vivo pulse 32P incorporation experiments provide evidence that greater than 80 axonemal components are labeled by 32P and that five of the radial spoke stalk polypeptides are modified to different extents.