Evidence for a uridine-5′-diphosphate-glucose-protectedp-chloromercuribenzene sulfonic acid-binding site in sugarcane vacuoles

The uptake of uridine-5-diphosphate (UDP) glucose into vacuoles isolated fromSaccharum sp. cells was fully inhibited by pretreatment with 50 Mp-chloromercuribenzenesulfonic acid (PCMBS) and was not affected by N-ethylmaleimide up to a concentration of 5 mM. The addition of 10 mM UDP-glucose during the pretreatment partially protected the uptake mechanism from PCMBS inhibition, while the presence of adenosine-5-diphosphate (ADP) glucose or of various hexose-phosphates had no protective effect. Parallel experiments on the binding of [²⁰³Hg]PCMBS to the vacuoles showed that UDP-glucose and UDP added at 10 mM concentrations caused a 40% decrease in the binding of PCMBS while ADP-glucose did not inhibit the binding. The results indicate the presence in a previously proposed group translocator of at least one site that can bind UDP-glucose. This site, which is blocked by PCMBS, interacts with the nucleotide moiety of UDP-glucose.Abbreviations ADP-glucose adenosine-5-diphosphate glucose - PCMB p-chloromercuribenzoic acid - PCMBS p-chloromercuribenzenesulfonic acid - UDP uridine-5-diphosphate - UDP-glucose uridine-5-diphosphate glucose     

Ultrastructure of Sporothrix schenckii treated with iodine-potassium iodide solution

The ultrastructural changes produced by iodine-potassium iodide solution on yeast cells of Sporothrix schenckii were investigated by transmission electron microscopy in order to clarify the mechanism of oral potassium iodide therapy for sporotrichosis. Yeast cells were dipped with solutions containing various concentrations of iodine. The rate of germination decreased markedly between the range of iodine concentrations from 0.63 g/ml to 5.0 g/ml. No significant ultrastructural changes were seen at the concentration of the iodine of 1.25 g/ml (80% germination) or less. In the concentration of 2.5 g/ml (50% germination), normal cells and degenerated cells coexisted. When the cells were treated with 5.0 g of iodine per ml (0% germination) or more, their interior structures were completely destroyed. It is assumed that iodine treatment of the organism causes rapid destruction in the whole cell.     

Induction of antifreeze protein production by juvenile hormone in larvae of the beetle,Dendroides canadensis

Summary Larvae of the beetleDendroides canadensis accumulate protein antifreezes during the winter.D. canadensis which were collected in the early fall, prior to the initiation of cold hardening processes, were treated with either 3.3 or 6.6 g juvenile hormone I topically in acetone and maintained for 21 days under normally non-inductive acclimation conditions (16 light/8 dark, 20 °C). Hormone treated animals significantly elevated the levels of antifreeze protein in their hemolymph compared to those of acetone treated and untreated controls or animals measured on the day of collection. D. canadensis treated with the anti-JH compound precocene II (P2) in acetone for 24 h at a concentration of 20 g/cm² (a dose below LD₅₀ for behavioral survival) and then maintained under acclimation conditions conducive to antifreeze protein production (8 light/16 dark, 20 °C) for 2 weeks failed to elevate levels of antifreeze. Acetone treated control animals accumulated a significant concentration of antifreeze protein.D. canadensis were also treated with 20 and 150 g/cm² P2 (a dose below the LD₅₀ for gross survival) followed by acclimation to short (8 h) photoperiod at 10 °C. All animals receiving the higher P2 dosage failed to elevate antifreezes while only 42.9% of the individuals treated with the lower dosage initiated antifreeze protein production. In contrast, over 80% of untreated and 70% of acetone treated controls responded to these inductive acclimation conditions by elevating antifreeze concentrations.These results indicate that juvenile hormone participates in the seasonal control of antifreeze protein production inDendroides canadensis. Since this species does not enter a diapause state prior to or throughout the winter this is the first evidence establishing a direct hormonal mechanism involved with insect cold hardiness.     

Enhanced in vivo sensitivity to interferon with in vitro resistant B16 tumor cells in mice

Mouse B16 melanoma cells rapidly develop resistance to the antiproliferative effects of interferon (IFN) and interferon (IFN) when they are exposed to the interferons in vitro. This resistance was characterized to be non-genetic and dose-dependent, and does not alter other IFN-induced effects such as antiviral effects and elevation of 2,5-oligoadenylate synthetase activity in IFN-treated cells. The study of these IFN-resistant cells has been extended to an in vivo tumor model. Resistance, if it occurred in vivo, did not adversely affect the survival of IFN-treated mice. Further, IFN-treated mice inoculated with B16 cells that were resistant in vitro (B16^res cells) survived significantly longer than IFN-treated mice inoculated with B16 cells that were sensitive in vitro. The IFN-treated B16^res-inoculated mice had a significantly higher cure rate as well. The prolonged survival of the mice bearing B16^res cell tumors did not seem to be caused by the slower growth rate of the B16^res cells, since experiments performed with a tenfold higher B16^res cell inoculum and a tenfold lower B16 cell inoculum did not show any change in the survival pattern. It is clear that in vitro resistant B16^res cells are more sensitive to antitumor effects induced by IFN in vivo than in vitro sensitive B16 cells.Supported by U. S. Public Health Service grant no. CA50752 awarded by the National Cancer Institute, Department of Health and Human Services (W. R. F.) and by a James W. McLaughlin Fellowship (C. M. F.)     

A monoclonal antibody recognizes a 65 kDa higher plant membrane polypeptide which undergoes cation-dependent association with callose synthase in vitro and co-localizes with sites of high callose deposition in vivo

Summary A monoclonal antibody (MAb) capable of immobilizing detergent-solubilized UDP-glucose: (13)--glucan (callose) synthase activity from higher plants has been selected and characterized. On Western blots this MAb recognizes a polypeptide of about 65 kDa found in membranes isolated from a variety of plant sources. The polypeptide recognized by this MAb does not appear to bind the substrate UDP-glucose, and evidence is presented which indicates that this polypeptide associates with the enzyme complex in a cation-dependent manner under conditions where the callose synthase assumes a larger size. Indirect immunofluorescence localization with this MAb was positive with sieve plates of cucumber (Cucumis sativus) seedlings, and with plasmodesmata of onion (Allium cepa) epidermal cells, both being sites of localized, stress-induced callose deposition.Abbreviations BSA bovine serum albumine - DMSO dimethylsulf-oxide - DTT dithiothreitol - FITC fluorescein isothiocyanate - HB Hepes buffer - HBS Hepes buffer plus 0.15 M NaCl - IgG immuno-globulin G - MAb monoclonal antibody - MSB microtubule stabilizing buffer - NP 40 Nonidet P 40 - PBS phosphate buffered saline - SDS-PAGE sodium dodecylsulfate polyacrylamide gel electrophoresis - UDP uridine diphosphate - UV ultraviolet     

Silicon carbide fiber-mediated stable transformation of plant cells

Summary Maize (Zea mays, cv Black Mexican Sweet) (BMS) and tobacco (Nicotiana tabacum, cv Xanthi) tissue cultures were transformed using silicon carbide fibers to deliver DNA into suspension culture cells. DNA delivery was mediated by vortexing cells in the presence of silicon carbide fibers and plasmid DNA. Maize cells were treated with a plasmid carrying both the BAR gene, whose product confers resistance to the herbicide BASTA, and a gene encoding -glucuronidase (GUS). Tobacco cells were treated with two plasmids to co-transfer genes encoding neomycin phosphotransferase (NPTII) and GUS from the respective plasmids. Thirty-four BASTA-resistant BMS colonies and 23 kanamycin-resistant tobacco colonies recovered following selection contained intact copies of the BAR gene and NPTII genes, respectively, as determined by Southern blot analysis. Sixty-five percent of the resistant BMS colonies and 50% of the resistant tobacco colonies also expressed GUS activity. Intact copies of the GUS gene were observed in Southern blots of all resistant BMS and tobacco colonies that expressed GUS activity. These results indicate that a simple, inexpensive DNA delivery procedure employing silicon carbide fibers can be used to reproducibly transform cells of both monocotyledonous and dicotyledonous plant species.Mention of a trademark, vendor, or proprietary product does not constitute a guarantee or warranty of the product by the University of Minnesota or the USDA, and does not imply its approval to the exclusion of other products or vendors that may also be suitableCooperative investigation of the Minnesota Agriculture Experiment Station and the US Department of Agriculture, Agricultural Research Service. Supported in part by grants from The Quaker Oats Company, and Midwest Plant Biotechnology Consortium, USDA Subgrant # 593-0009-04. Minnesota Agricultural Experiment Station Publication No. 19,226.     

Receptor expression and oxidase activity in human neutrophils: Regulation by granulocyte-macrophage colony-stimulating factor and dependence upon protein biosynthesis

Incubation of human bloodstream neutrophils with 50 u/ml recombinant granulocyte-macrophage colony-stimulating factor (rGM-CSF) primed the respiratory burst (as assessed by fMet-Leu-Phe stimulated luminol-dependent chemiluminescence) and resulted in a rapid (within 15 min) upregulation of expression of CD11b and CD18 (as measured by FACS analysis). This rapid priming and modulation of receptor expression was not inhibited by cycloheximide and hence appeared to be independent ofde novo protein biosynthesis. When neutrophils were incubated for up to 5 h in culture, the fluorescence distributions of CD11b and CD18 declined indicating the loss of expression of these receptors as the neutrophils aged, but in rGM-CSF treated suspensions receptor expression was maintained. When neutrophils were incubated in the presence of cycloheximide, they progressively lost their ability to generate reactive oxidants in response to fMet-Leu-Phe so that by 5 h incubation with this inhibitor they could only generate about 25% of the oxidative response stimulated in untreated cells, and the expression of CD16 and CD18 was grossly impaired. Similar effects were observed in rGM-CSF treated suspensions except that cycloheximide required longer incubation times (typically 4–5 h) before impairment of function or receptor expression occurred. These data show thatde novo protein biosynthesis is required for both the maintenance of neutrophil function and also for the continued expression of some plasma membrane receptors.Abbreviations fMet-Leu-Phe N-formylmethionyl-Leucyl-Phenylalanine - rGM-CSF recombinant granulocyte-macrophage colony-stimulating factor - FITC fluorescein isothiocyanate conjugate - Luminol 5-amino-2,3-dihydrophthalazine-1,4-dione     

The role of intracellular zinc in modulation of life and death of Hep-2 cells

Varying intracellular concentrations of zinc in laryngeal Hep-2 cells in relation to changing cultivation conditions in vitro were determined by atomic absorption spectrophotometry. Upon standard cultivation in DMEM with 10% serum, the mean concentration of zinc was determined at 0.88 ± 0.09 g/mg protein, with substantially decreased values in the cells exposed to a low-serum medium. Next, the study of the effects of a series of physiological and supraphysiological concentrations of ZnSO₄ on laryngeal cells and their correlation with determined intracellular concentrations of zinc was performed. It was found that zinc concentrations above 100 M were toxic to Hep-2 cells, inducing cell death in the interval of 96 h as determined by videomicroscopy, selective nuclear staining, and immunofluorescence detection of caspase-3 and specific cytokeratin 18 fragment. Both types of cell death were observed, with apoptosis being induced at moderately toxic zinc concentration of 150 M and necrosis at higher zinc concentrations of 300 M and 750 M, respectively. Lower concentrations (1.5–100 M), on the other hand, did not produce any measurable changes in cell morphology and function in the same time interval. Zinc at concentration of 1.5 M was found to slightly enhance proliferation of Hep-2 cells up to the certain time point, which seemed to correlate with maximal tolerable momentary intracellular level of zinc. These results illustrate the importance of determining the intracellular levels of zinc when trying to characterize the effect of exogenous zinc on life and death of laryngeal cells.     

Effects of photoperiod and temperature on testicular development in male ayu,Plecoglossus altivelis

Synopsis Growth, gonadosomatic index and plasma steroid profiles in male ayu,Plecoglossus altivelis, cultured under short/long photoperiods and cool/warm temperatures were determined. Juvenile males were assigned to each of four different photoperiod/temperature regimes (16 L/18°C, 16 L/24°C, 8 L/18°C and 8 L/24°C) at random. Fish were killed and examined bi-weekly over the following 16 weeks. Mean body weight in the 16 L/18°C treated fish was the highest among four treated groups. No significant differences between body weights of the 16 L/24°C, 8 L/18°C and 8 L/24°C treated groups were observed. Ayu in the 8 L/18°C treated group had the highest values of gonadosomatic index, plasma testosterone (T) and 17-hydroxyprogesterone (17-OH P). No significant differences of plasma E₂ were observed among the treated groups. In the 8L/18°C and 8L/24°C groups, peak levels of 17-OH P occurred after 12 and 14 weeks of treatment, respectively. No peak levels of plasma T and 17-OH P were observed in 16 L/18°C or 16 L/24°C treated ayu. Spermiation occurred only in ayu with 8 L/18°C treatment. The data suggest that testicular development in ayu is temperature and photoperiod dependent: short photoperiod and cool temperature favour gonadal development.     

Induction of CYP3A and associated terfenadineN-dealkylation in rat hepatocytes cocultured with 3T3 cells

Long-term culture of hepatocytes has been challenged by the loss of differentiated functions. In particular, there is a rapid decline in cytochrome P450 (CYP). In this study, we cocultured rat hepatocytes with 3T3 fibroblasts for 10 days, and examined hepatocyte viability, morphology, and expression of CYP3A. Terfenadine was incubated with the cultures, and its biotransformation was quantitatively analyzed by HPLC. Terfenadine is metabolized by two major pathways:C-hydroxylation to an alcohol metabolite which is further oxidized to a carboxylic acid, andN-dealkylation to azacyclonol. In rat liver, only theN-dealkylation pathway appears to be mediated by CYP3A since anti-rat CYP3A antibody inhibited azacyclonol but not alcohol metabolite formation in incubations of terfenadine with liver microsomes. Freshly isolated rat hepatocytes were seeded on top of confluent 3T3 cells. Cultures were maintained in Williams' E medium supplemented with 10% fetal bovine serum and either 0.1 mol/L or 5 mol/L dexamethasone. In pure hepatocyte cultures, viability, as determined by lactate dehydrogenase (LDH) activity, decreased steadily to less than 30% of initial levels by day 10. In cocultures, LDH activity remained high and was 70% of initial levels on day 10. The half-life of terfenadine disappearance was optimally maintained in cocultures treated with 5 mol/L dexamethasone, and was associated with the increased formation of azacyclonol. On day 5, nearly 50% of added 5 mol/L terfenadine was converted to azacyclonol within 6 h, whereas the conversion was only 4% on day 1. Western and RNA-slot blot analyses confirmed that treatment with 5 mol/L dexamethasone induced CYP3A mRNA expression and CYP3A protein expression. This coculture system could offer a useful approach in the study of drugs and xenobiotics metabolized by CYP3A.Abbreviations BSA bovine serum albumin - CYP cytochrome P450 - DMSO dimethyl sulfoxide - LDH lactate dehydrogenase - PCN pregnenolone-16-carbonitrile - SDS sodium dodecyl sulfate - SSC saline sodium citrate     

Cell cycle duration and time of DNA synthesis in binucleate cells induced inV. faba meristems by caffeine or isobutyl-methylxanthine

Summary Lateral roots ofVicia faba were treated with a solution of 5-aminouracil (3.93×10^–3M) for 6 hours. After 15 hours roots were recovering from the temporary inhibition of mitosis induced by 5-AU and were approaching peak mitotic indices; they were then treated with 0.1% caffeine or 0.1% isobutylmethylxanthine (IBMX) for 1 hour. Treatment with methylxanthines when the mitotic index was high gave relatively high yields of binucleate cells, 3.8 to 7.5%. DNA synthesis, cell cycle duration and nuclear growth were determined for binucleate cells. Caffeine induced binucleate cells underwent a marked reduction in nuclear volume, from 1,074 m³ at 1+1 hours to 534 m³ at 1+14 hours. Only 15% of these binucleates entered S phase; those that did so were in mitosis or had divided by 1+14 hours. We conclude that 85% of the binucleate cells are so inhibited by caffeine that their G₁ is extended to>14 hours or that they are no longer proliferating cells. IBMX-induced binucleate cells, by contrast, did enter S phase and many of them also divided. Though in IBMX-induced binucleate cells there was also a decrease in nuclear volume up to 1+10 hours, subsequently mean nuclear volume increased e.g. at 1+16 and 1+18 hours. Both caffeine and IBMX treatments resulted in decreases in mean volume of prophase nuclei of mononucleate cells; this is further evidence that both methylxanthines inhibit the macromolecular synthesis required to sustain nuclear growth. It also suggests that nuclear division can be initiated at considerably lower nuclear volumes than those of untreated cells. We suggest that caffeine may act as a mimic of the normal mechanism that regulates the switch from a proliferating to a non-proliferative condition.     

Uteroglobin in the rabbit

Summary Rabbit uterine uteroglobin (UGL) was studied by electrophoretic and immunological methods following normal copulation, after ovariectomy and progesterone treatment, 17-oestradiol and combined progesterone treatment, 17-oestradiol treatment alone and after HCG-induced pseudopregnancy. Electrophoretic studies show the amount of ULG in uterine secretions, the immunological investigations indicate the intracellular localization of ULG and the distribution of ULG-positive cells in the endometrium.No obvious differences were found between the uteri 7 days after injection with chorion-gonadotropin and those 7 days following normal copulation. No differences could be demonstrated between the uteri of animals 35 days following ovariectomy and subsequent progesterone treatment on Days 31–33 and those of normal 7 d. post coitum (p.c.) animals. Uteri from animals treated with progesterone on Days 2–5 p.c. contained more ULG-positive cells than controls. 17-oestradiol treatment with and without subsequent progesterone treatment resulted, in both gravid and ovariectomized animals, in the formation of a tall columnar endometrial epithelium. Treatment with 17-oestradiol on Days 1 and 2 p.c. led to a decrease in the number of UGL-positive cells at 7 days p.c. Even after ovariectomy with 17-oestradiol substitution, UGL-positive cells were still present in the endometrium. However a secretion of any magnitude could not be detected. The importance of differentiation between synthesis and secretion (= release) as distinct phases of the glandular response is especially emphasised by the latter findings.Supported by Grant No. Ki 154/5-6, Deutsche Forschungsgemeinschaft     

Glucose phosphotransferase and intracelular trafficking

Glycoproteins containing phosphodiester-linked glucose residues have recently been described. The synthesis of this structure occurs due to the intact transfer of glucose-1-phosphate from UDP-glucose and is catalyzed by the enzyme glucose phosphotransferase (GlcPTase). The endogenous acceptors for GlcPTase have been characterized as to molecular weight following incubation of selected homogenates with (³²P)UDP-glucose. These glycoproteins are distinct from the lysosomal hydrolases recognized by the GlcNAc phosphotransferase. The transfer of ³²P from (³²P)UDP-Glc can also be detected when the nucleotide sugar is microinjected into the cytoplasm of individual neurons in Aplysia. The phosphorylated acceptors in this system seem to be predominantly two glycoproteins that are subjected to rapid axoplasmic transport. The possible role of this post-translational modification in the intracellular trafficking of a subset of newly synthesized glycoproteins is discussed.     

Effect of 17β-estradiol on cells stained for FSHβ and/or LHβ in the dog pituitary gland

Summary The effect of long-term treatment (52 weeks) with high doses of 17-estradiol (1.28 mg/kg/week intramuscularly) on gonadotrophs was studied in the pituitary gland of the beagle bitch. For immunochemical staining the immunoperoxidase technique and antisera to the specific beta () subunits of FSH and LH were employed. For control purposes antisera to the following hormones were also used: bovine TSH, canine GH, canine PRL and porcine ACTH¹. In the pars distalis and pars tuberalis of control bitches, in addition to the cells which react solely with antisera to either LH or FSH, most cells were reactive to both antisera. The cells stained for FSH were less numerous than those shown to contain LH. TSH, PRL, GH and ACTH/MSH were localized in distinctly different cell types in the pars distalis of all control animals. In the treated bitches, almost complete regression of cells classically identified as gonadotrophs and stained for LH was observed. On the other hand, using the antiserum to FSH, selective immunochemical staining was localized in cells fitting the morphological characteristics of TSH cells. All these cells were also stained for TSH. However, a few cells were also shown to react solely with the antiserum to TSH. These cells, which seem to contain both TSH and FSH, were further clearly differentiated from PRL, GH and ACTH/MSH cells on the basis of their cytological features, intraglandular distribution and by immunochemical double staining. These observations support the concept that the one cell-one hormone theory may not necessarily apply to the glycoprotein hormones of the dog pituitary gland.Abbreviations of Hormones cited in this Paper ACTH Adrenocorticotropin - FSH Follicle Stimulating Hormone - GH Growth Hormone - LH Luteinizing Hormone - MSH Melanocyte Stimulating Hormone - PRL Prolactin - TSH Thyrotropin The authors are grateful to Mrs. K. Oertel for carrying out the experimental work on animals, to Mrs. B. Schilk and Miss U. Tüshaus for their excellent technical assistance, and to Dr. P. Günzel for his advice and encouragement     

Glutaraldehyde-fixation of yeast cells: Kinetics of a model system for enzyme cytochemistry

The kinetics of glutaraldehyde inactivation of a protoplasmic (-fructofuranosidase) and an extracytoplasmic (acid phosphatase) enzyme inSaccharomyces rouxii cells were studied at pH 5.5 and 30°C. The effects of glutaraldehyde concentration (0.5–3%), pH value, and temperature were surveyed by varying the fixation conditions. Cells from 1- to 10-day cultures retained 50–75% of their acid phosphatase activity and 15–24% of their -fructofuranosidase activity after 1-h exposures to 0.5% glutaraldehyde. The surviving -fructofuranosidase activity remained physically cryptic and was revealed only after further membrane perturbation with ethyl acetate. This crypticity barrier disappeared after overnight incubation of the treated cells at 4°C, with or without added glutaraldehyde, during which time the enzyme was resistant to further inactivation. The velocity ratio for raffinose versus sucrose, as substrate, decreased in treated cells, and changes inV _max andK _m were indicative of frank destruction of some enzyme molecules as well as modification of survivors. A comparable set of changes was also generated by treating cell-free extract with glutaraldehyde. Glutaraldehyde (0.5%) killed all yeast cells at 30°C within 5 min; at 4°C survival rates were quite high—81% after 15 min and 65% after 1 h. The bearing of these examples of enzyme inactivation, permeability barrier abolition, and structural stabilization on the general problems of yeast cytochemistry is discussed.     

The therapeutic effects of an immunopotentiator,PS-K,on 3-methylcholanthrene-induced autochthonous tumors in C57BL/6 mice in combination with the surgical removal of primary sites

Summary We investigated the therapeutic effects of an immunopotentiator PS-K on recurrent or metastatic tumors observed after the surgical removal of MCA-induced primary tumors in autochthonous C57BL/6 mice and on the survival time of treated mice. The MST of mice treated with PS-K at various times (59.8 63.4 days) was prolonged as compared with that of mice treated by surgery alone (48.6 days). Local recurrence of tumors was found in 36 of 66 mice (54.6%) treated by surgery alone, whereas it was inhibited significantly (P<0.05) when treatment with PS-K was started 1 day after the surgery and occurred in 22 of 64 mice (34.4%) when PS-K was given for 5 days in 1 week, or in 22 of 66 mice (33.3%) when PS-K was administered twice a week for 7 weeks. The MSTs of mice with local recurrence were also found to be prolonged as compared with those of mice treated by surgery alone (54.8 67.5 days vs 49.8 days). The MSTs of mice without tumor recurrence were also prolonged significantly (P<0.05 0.001) by combinations of PS-K at various times, although most of the mice died of metastatic tumors even in the groups of mice where a combined treatment with PS-K had been administered. The above findings suggest that the administration of PS-K inhibits the growth of recurrent or metastatic tumor cells in autochthonous mice after the surgical removal of the primary tumors.This work was supported in part by Grants in Aid for Cancer Research from the Japanese Ministries of Education, Science and Culture and of Health and Welfare Abbreviations used: MCA; 3-methylcholanthrene, CY; cyclophosphamide, MST; mean survival time     

Evaluation and first-year field testing of efficient vesicular arbuscular mycorrhizal fungi for inoculation of wetland rice seedlings

Grain yields of the rice cultivar Prakash were improved upon inoculation with Glomus intraradices and G. fasciculatum, by 11% and 8%, respectively, compared with an uninoculated control. The results indicate that the amount of phosphate fertilizer usually applied to rice may be decreased by 50%, without affecting yield, if G. intraradices is inoculated.The authors are with the Department of Agricultural Microbiology, University of Agricultural Sciences, GKVK Campus, Bangalore 560 065, India. ing author.     

Salinity studies with drought-resistant species of Sporobolus

Summary Dry matter productivity under saline conditions was compared in 5 desiccation-tolerant resurrection grasses and one desiccation sensitive species, all in the genus Sporobolus. S. stapfianus was the most salt tolerant, requiring 215 mole NaCl m^-3 to reduce shoot dry matter increments to 50% of increments in plants not treated with salt. (This was comparable to published values for the salt tolerant grass Diplachne fusca.) S. lampranthus was salt sensitive, requiring 35 mol m^-3 for 50% control yields. S. festivus, S. aff. Fimbriatus, and the deisccation sensitive S.pyramidalis was moderately tolerant (150–170 mol m^-3). The moderate salt resistance of S. aff. fimbriatus was attributed mainly to exclusion of NaCl by roots. Salt export through leaf surfaces was a minor factor. Half of the leaf mesophyll cells survived 50 min immersion in 200 mol NaCl m^-3. Plants of S. aff. fimbriatus and S. pyramidalis tolerated a broad range of soil pH. Plants of 4 desiccation tolerant Sporobolus species survived air-dryness following 3 weeks pretreatment with salinities up to 200 mol m^-3     

In vitro comparison of ceftazidime,aztreonam, cefpirome,gentamicin, imipenem,enoxacin, and ticarcillin plus clavulanic acid against 108 strains ofPseudomonas maltophilia

Pseudomonas maltophilia is an uncommon cause of hospital-acquired infection and is resistant to most of the antimicrobial agents used in the treatment of gram-negative infections. Susceptibility of 108 isolates ofP. maltophilia to ceftazidime, aztreonam, defpirome, gentamicin, imipenem, enoxacin, and ticarcillin plus clavulanic acid was determined by an agar dilution method. The isolates were in general resistant to the antibiotics. Imipenem and cefpirome were not active at clinically achievable levels. Of the isolates, 20% were susceptible to 16 g/ml ceftazidime, 53% were susceptible to 4 g/ml enoxacin, 10% were susceptible to 4 g/ml gentamicin, and 25% were susceptible to 64 g/ml ticarcillin plus 2 g/ml clavulanic acid.