Production of insulin-like growth factor I (IGF-I) and IGF-binding proteins by rat intestinal stromal cells in vitro

To determine if intestinal stromal cells secrete diffusible factors such as insulin-like growth factors (IGFs) capable of regulating epithelial cell growth in vitro, stromal cells were isolated by enzymatic digestion of rat intestine. Incorporation of [³H]thymidine into DNA and [¹⁴C]leucine into protein of IEC-6 cells, a model intestinal epithelial cell line, was significantly increased (two- to threefold) when the IEC-6 cells were co-cultured with stromal cells, relative to IEC-6 cells grown alone. Medium conditioned by stromal cells stimulated DNA synthesis of IEC-6 cells in a dose-dependent manner. Analysis of the conditioned medium revealed that intestinal stromal cells secreted IGF-I, but little IGF-II, in addition to an M _r 32,000 IGF-binding protein (IGFBP-2) and an IGFBP having M _r∼ 24,000. We conclude that rat intestinal stromal cells secrete one or more diffusible factors, which may include IGF-I and IGFBPs, capable of stimulating proliferation of IEC-6 cells in vitro. Received 25 August 1997; received after revision 7 November 1997; accepted 20 November 1997     

Osmotic adaptation of moderately halophilic methanogenic Archaeobacteria,and detection of cytosolicN,N-dimethylglycine

Methanohalophilus mahii SLP andMethanohalophilus halophilus Z-7982, two closely-related, moderately halophilic, methylotrophic methanogens, were tested for their adaptation to saline conditions. They grew in a wider range of salinities than previously reported, in a defined medium with as little as 0.1 M NaCl, and with a high as 4.0 M NaCl forM. halophilus and 4.5 M NaCl forM. mahii. Fastest growth occurred with 1.5 M NaCl forM. mahii and 1.0 M NaCl forM. halophilus. M. mahii also grew in media in which NaCl was replaced by sucrose or KCl as osmolytes up to the osmolal equivalent of 2 and 2.5 M NaCl (these media contained other sodium salts totaling about 0.1 M Na⁺). In media with either sucrose of KCl replacing NaCl,M. mahii grew fastest at osmolalities approximately equiosmolal to 1 M NaCl.M. mahii not only grew well at a wide range of osmosities, it also tolerated rapid shifts in osmolality. Cells subjected to a rapid 10-fold hypertonic shift resumed growth without a prolonged lag. When cells were subjected to a rapid 10-fold hypotonic shift, 90% of cells lysed, but the remaineder continued to swell with little further lysis during the next 45 min. Surviving cells resumed growth.Methanohalophilus strains grown in defined medium had low cytosolic Na⁺ concentrations; K⁺ concentrations were as high as 0.35 M. Organic osmotica in the cytosol include glycine betaine and larger amounts of N,N-dimethylglycine.     

Secretion of chitinase byAphanocladium album,a hyperparasite of wheat rust

Summary Aphanocladium album, a hyperparasite of wheat rust,Puccinia graminis vartritici, secretes chitinase when grown on a chitin-containing medium. This enzyme was purified and shown to attack the mycelium of the parasitized rust fungus.Supported, in part, by a grant from the Naef-Roth-Foundation.     

Complement evasion by the Lyme disease spirocheteBorrelia burgdorferi grown in host-derived tissue co-cultures: role of fibronectin in complement-resistance

The effectiveness of complement-mediated killing ofBorrelia burgdorferi, the causative agent of Lyme disease, in the presence of host-derived tissues was studied. Second and high passage forms ofB. burgdorferi 297 isolate were grown in a LEW/N rat joint tissue co-culture system and in artificial BSK medium. Guinea pig complement and third week immune serum from hamsters with experimental Lyme disease were added to the cultures. Both high and low passage borrelia grown in BSK medium died and did not revive after 3 weeks incubation in BSK medium. However, 5–12% of tissue co-cultured borrelia survived the first complement-mediated lysis. Repeated re-growth and lysis cycles in tissue co-culture resulted in isolation of an 85% complement-resistant population ofB. burgdorferi. Joint tissue culture supernatant collected on the third day of tissue culture, and fibronectin (25 g/ml), also protected spirochetes from complement-mediated lysis in contrast to BSK or fresh co-culture medium. Complement-mediated lysis may not be an effective mechanism in eradication of borrelia, and the chronicity of Lyme disease may be due to resistance ofB. burgdorferi variants to host immune defense mechanisms in the presence of host-derived tissues.     

Abbauprodukte von Simazin in Gramineen

Summary Coix lacryma-jobi L., about 20 days old and grown on watercultures, were fed with¹⁴C-ring-labelled simazine. After freeze drying, the plant tissue was extracted with chloroform and 80% ethanol. The ethanol extractable activities were fractionated on a cation exchange column. The radioactive metabolites seem to be identical with 2-hydroxy-4, 6-diethylamino-s-triazine (hydroxysimazine), 2-hydroxy-4, 6-diamino-s-triazine (ammelin) and 2-hydroxy-4-ethylamino-6-amino-s-triazine.     

Shoot regeneration fromAgrobacterium tumefaciens-induced tumors of a tropical timber tree,Fagraea fragrans

Summary Agrobacterium tumefaciens A208 with nopaline plasmid pTiT37 was used to obtain stem tumors on plantlets ofFagraea fragrans grown in vitro. Bacterial elimination and tissue proliferation were simultaneously achieved by growing tumors on cefatoxime medium. After some tissue growth the shoots regenerated. An examination of these showed the presence of nopaline, indicating genetic transformation by T-DNA.     

Sulla biochimica della fermentazione citrica da parte dell'Aspergillus niger

Summary In a strain ofAspergillus niger grown in Bernhauer medium, oxalacetic decarboxylase activity increased, while citric acid accumulated in the medium. The mechanism of citric acid accumulation is discussed.     

Sulla biochimica della fermentazione citrica da parte dell'Aspergillus niger

Summary In a strain ofAsp. niger grown inBernhauer medium, succinic-dehydrogenase activity decreased and asparticglutamic transaminase activity remained practically constant, while citric acid accumulated in the medium.     

Vergleich der Alkaloidbildung vonClaviceps purpurea in parasitischer und saprophytischer Kultur

Summary Three monoconidial strains ofClaviceps purpurea were grown parasitically on rye and saprophytically on a nutrient medium. The qualitative alkaloid spectra were nearly identical in the sclerotia and in the corresponding saprophytic cultures, while the quantitative distribution of some of the alkaloids differed considerably.

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53. Mitteilung über Mutterkornalkaloide. 52. Mitt. s. Helv. chim. Acta45, 276 (1962).     

Potentiation by taurine of the inotropic effect of ouabain and the content of intracellular Ca++ and taurine in the heart

Summary Under certain conditions, taurine (3.0 mM) potentiated cardiac contractile response to ouabain in the normal medium. The potentiation by taurine was also observed in the low K⁺ medium, in which the positive inotropic effect of ouabain increased. The potentiation as seen in both media was, at least in part, due to the increase by taurine of Ca⁺⁺ content in the heart. Taurine in the heart was not directly related to this potentiation.     

Trace metals especially Fe+++ as dietary factors for leafhoppers

Summary Some trace metals are required for development and reproduction, and therefore for continuous rearing of the aster leafhopper,Macrosteles fascifrons, on a holidic diet. Requirement for Fe⁺⁺⁺ becomes apparent immediately in the 1st generation; for Cu⁺⁺ and Zn⁺⁺, in the 3rd. The leafhopper has grown normally and continuously for 3 generations in the absence of manganese.We acknowledge the Minnesota Agricultural Experiment Station and the National Institute of Allergy and Infectious Diseases, USA, for financial supports.     

Bromothricin

Summary Streptomyces antibioticus (Waksman andWoodruff)Waksman andHenrici 1948, strain Tü 99, produced Bromothricin instead of Chlorothricin, when it was grown in a nutrient medium containing 0.5% potassium bromide. The properties of bromothricin are very close to those of chlorothricin. Its nature was elucidated by degradation to methyl 5-bromo-2-methoxy-6-methylbenzoate.     

Metabolic studies of Hg-203 onChlamydomonas reinhardi

Summary Sterile cultures ofChlamydomonas reinhardi, WT⁺, were treated with Hg-203 at 25°C to identify probably formed volatile mercury compounds. Experiments were performed with living and dead cells under aerobic or anaerobic conditions, respectively, and the mercury concentration was measured in the system algae/nutrient medium. We found a timerelated decrease of mercury concentration in the cell suspension and the cell-free nutrient medium due to a reduction of Hg⁺⁺ to Hg⁰, probably caused by extracellular enzymes; monomethyl or dimethyl mercury could not be detected.This work was supported by a grant of Österreichisches Bundesministerium für Gesundheit und Umweltschutz.     

Ca2+-dependence and metabolic status of an obligate thermophile,Thermoactinomyces vulgaris,under shake culture conditions

Summary Ca²⁺ stimulates germination ofT. vulgaris spores. There is a higher mycelial yield as well as higher protein, DNA, RNA and free Pi content in cultures grown in the presence of Ca²⁺ as compared to those grown in the absence of this divalent cation.Grateful thanks are due to Professor R. P. Roy for providing the necessary facilities. V. P. S. acknowledges with thanks the receipt of a Post Doctoral Research Fellowship of the Council of Scientific and Industrial Research, New Delhi.     

In vitro flowering of orange jessamine (Murraya paniculata (L.) Jack)

Branch internodes ofMurraya paniculata flowered in vitro on half-strength MT medium containing 5% sucrose supplemented with cytokinins. The cytokinins only induced vegetative shoots from the epicotyl of seedlings. The highest percentage of flowering (76.7% of the explants) was achieved from branch internodes of flowering plants close to the apex, on half-strength MT medium containing 5% sucrose and 0.001 mg l¹ benzyladenine (BA) in light. Flowering required two days' exposure to BA, but shoot formation could be initiated even without exposure to BA.     

An experimental approach to pH measurement in the intercellular free space of higher plant tissues

Summary An experimental approach to the measurement of pH in the free space of plant tissues was made, using both metal minielectrodes and H⁺-sensitive resin glass microelectrodes inserted in small environments artificially created inside the tissue. Experiments were carried out on the parenchyma of higher plants (corn, potato, squash,Senecio herraianus), monitoring pH changes in the free space as a function of the pH of the external medium. The pH in the free space has been found to be different from that of the surrounding solution and its variation in time much slower than would be predicted by assuming that simple diffusion of H⁺ ions took place. The results agree with the hypothesis that the free space behaves as a compartment distinct from both the cytosol and the surrounding medium.     

<Emphasis Type="Italic">Trichomonas vaginalis</Emphasis> degrades nitric oxide and expresses a flavorubredoxin-like protein: a new pathogenic mechanism?

Besides possessing many physiological roles, nitric oxide (NO) produced by the immune system in infectious diseases has antimicrobial effects. Trichomoniasis, the most widespread non-viral sexually transmitted disease caused by the microaerophilic protist Trichomonas vaginalis, often evolves into a chronic infection, with the parasite able to survive in the microaerobic, NO-enriched vaginal environment. We relate this property to the finding that T. vaginalis degrades NO under anaerobic conditions, as assessed amperometrically. This activity, which is maximal (133 ± 41 nmol NO/10⁸ cells per minute at 20°C) at low NO concentrations ( 1.2 M), was found to be: (i) NADH dependent, (ii) cyanide insensitive and (iii) inhibited by O₂. These features are consistent with those of the Escherichia coli A-type flavoprotein (ATF), recently discovered to be endowed with NO reductase activity. Using antibodies against the ATF from E. coli, a protein band was immunodetected in the parasite grown in a standard medium. If confirmed, the expression of an ATF in eukaryotes suggests that the genes coding for ATFs were transferred during evolution from anaerobic Prokarya to pathogenic protists, to increase their fitness for the microaerobic, parasitic life style. Thus the demonstration of an ATF in T. vaginalis would appear relevant to both pathology and evolutionary biology. Interestingly, genomic analysis has recently demonstrated that Giardia intestinalis and other pathogenic protists have genes coding for ATFs.Received 1 November 2003; received after revision 5 January 2004; accepted 13 January 2004     

Blockade by zinc ions of K+-induced contraction and calcium in guinea pigTaenia coli

Preincubation with 0.3 mM Zn²⁺ markedly inhibited both the tonic response and Ca²⁺ binding at low affinity sites induced by K⁺ (60 mM), with smaller effects on the phasic response and the high affinity Ca²⁺ sites, inTaenia coli. However, when the muscle was kept in Zn²⁺-containing medium following the first stimulation with the K⁺, the phasic response and the high affinity Ca²⁺ sites were more severely inhibited during the second stimulation with K⁺. This probably indicates that Zn²⁺ reduced the tonic tension response to K⁺ mainly by inhibiting Ca²⁺ influx at the cell membranes ofTaenia coli. However, when Zn²⁺ is continuously present, Ca²⁺ is not supplied at the storage sites and is not available for the phasic response to a second stimulation with K⁺.     

Effects of corpora cardiaca extract,furosemide and ion substitution on sodium and chloride flux in perfused Malpighian tubules ofLocusta

Treatment with the co-transport inhibitor, furosemide decreased³⁶Cl^– flux across perfused Malpighian tubules ofLocusta. However, exclusion of³⁶Cl^– from the bathing medium had not effect on²²Na⁺ flux whereas substitution of bathing medium Na⁺ by K⁺ increased³⁶Cl^– flux. Diuretic extract of corpora cardiaca increased²²Na⁺ (by 106%) and³⁶Cl^– (by 335%) fluxes differentially.