Stimulation of root and somatic embryo production in Euonymus europaeus L. by an inhibitor of polyamine biosynthesis

In vitro formation of roots and somatic embryos is obtained from cotyledon explants of a Spindle tree (Euonymus europaeus L.) cultured on two different media: a medium inducing callus formation and the production of roots, and a medium inducing callus formation, root and somatic embryo production. We studied the effects of -difluoromethylornithine (DFMO), a specific, irreversible inhibitor of ornithine decarboxylase (ODC) on root and somatic embryo production, growth and titers of putrescine in Euonymus explants and explant-derived calli. Early changes in putrescine levels were detected in both cultures before the visible emergence of roots or somatic embryos. DFMO rapidly inhibited putrescine accumulation and growth in non-embryogenic calli and highly stimulated rooting activity. DFMO partially inhibited putrescine accumulation in embryogenic calli. This inhibition had no effects on callus growth but significantly reduced the time of emergence of roots and highly stimulated somatic embryo production. The relationship among putrescine, putrescine metabolism, growth, root and somatic embryo formation is discussed.     

Activity of β-galactosidase in homogenates and isolated microvilli fraction of jejunal mucosa from suckling rats

1. beta-Galactosidase activity was studied in homogenates and isolated microvilli fraction of jejunal mucosa from 14-day-old suckling rats. o-Nitrophenyl beta-d-galactoside served as the substrate. 2. The microvilli fraction contains about one-third of the total activity of the original homogenate. 3. The pH optimum of the beta-galactosidase was 3.5 in the total homogenate and supernatant fraction, whereas in the microvilli fraction the maximum activity was at pH5.5. 4. This work gives further support to the view that two beta-galactosidases exist in the jejunal mucosa.     

Variability amongThymelaea hirsuta (L.)Endl. populations in Egypt

The present study depicts the presence of a gradient in the morphological characters ofThymelaea hirsuta (L.)Endl. leaves which correlated with the environmental gradient prevailing in the Western Mediterranean region of Egypt. The less arid and more calcareous habitats harbour individuals with obtuse and gentle curved leaf apices and gentle involute leaf margins. With the increase of aridity and decrease of CaCO₃, the leaf apices become acute and strongly curved, and the leaf margins become strongly involuted. Significant variations in seed weight, seedling emergence and viability of seed embryos inT. hirsuta, in relation to habitat types, are also shown and discussed.     

Fatty Acid Composition of the Peribacteroid Membrane and the ER in Nodules of Glycine max Varies after Infection by Different Strains of the Microsymbiont Bradyrhizobiumjaponicum

The fatty acid composition of ER, Golgi and peribacteroid membrane (PBM) from root nodules formed on Glycine max after infection with different strains of Bradyrhizobium japonicum has been analysed by gas chromatography. In each plant-microsymbiont combination the fatty acid composition (FAC) of the PBM is distinct from ER and Golgi. The similarity between ER and PBM fatty acid composition is significantly stronger than between Golgi and PBM. In addition the fatty acid composition of all membrane systems in nodules is affected by the microsymbiont strain. A comparison of four strains of Bradyrhizobium japonicum grown in agar surface culture and isolated as the symbiotic bacteroids reveals a decrease in oleic acid during bacteroid differentiation.     

Short- and Long-Term Alterations of Gene Expression in Limbic Structures by Repeated Electroconvulsive-Induced Seizures

Rats were submitted to a series of 10 daily electroconvulsive shocks (ECS). A first group of animals was killed 1 day after the last seizure and a second group 30 days later. Tyrosine hydroxylase (TH) activity was measured using an in vitro assay in the nucleus caudatus, anterior cortex, amygdala, substantia nigra, ventral tegmental area, and locus ceruleus. The mRNA corresponding to this enzyme (TH-mRNA) was evaluated using a cDNA probe at the cellular level in the ventral tegmental area, substantia nigra, and locus ceruleus. Met-enkephalin (MET)-immunoreactivity and the mRNA coding for the preproenkephalin (PPE-mRNA) were assayed in striatum and the central nucleus of the amygdala. The day after the last ECS an increase of TH activity was observed in the ventral tegmental area, locus ceruleus, and substantia nigra in parallel with a similar increase in the amygdala and striatum; in the anterior cortex TH activity remained unchanged. TH-mRNA was increased in the locus ceruleus, evidencing the presence in this structure of a genomic activation. The amounts of MET and PPE-mRNA were unaffected in the striatum but increased in the amygdala. Thirty days after the last ECS we observed a decrease of TH activity in the amygdala and of TH-mRNA amount in the ventral tegmental area. In the locus ceruleus TH-mRNA remained higher in treated animals than in controls whereas TH activity returned to control levels. These results demonstrate that a series of ECS induces an initial increase of the activity of mesoamygdaloid catecholaminergic neurons followed by a sustained decrease through alterations of TH gene expression which could mediate the clinical effect of the treatment.     

City spore concentrations in the European Economic Community (EEC). VI. Poaceae (Grasses), 1982–1986

Summary Airborne grass-pollen concentrations in six cities in the EEC are compared, based on observations from five years, 1982–1986. Results show that there are quantitative differences both between the monitoring stations and between the years. Very provisionally, the average seasonal total of the European urban airborne grass-pollen concentration can be put at 4 to 5000 per m³ of air. Also qualitatively, regarding the seasonal fluctuations, there are differences between the stations, and between the years. Generally, the results confirm that June is the most typical grass-pollen month in northwestern Europe, whereas in mediterranean Europe May is the more prominent grass-pollen period. There seems to be little coherence between the starting dates of the grass-pollen season even at relatively nearby stations in northwestern Europe, suggestive for a great influence of the actual weather situation.     

Enzymatic dehalogenation of pentachlorophenol by extracts from Arthrobacter sp. strain ATCC 33790.

Arthrobacter sp. strain ATCC 33790 was grown with pentachlorophenol (PCP) as the sole source of carbon and energy. Crude extracts, which were prepared by disruption of the bacteria with a French pressure cell, showed no dehalogenating activity with PCP as the substrate. After sucrose density ultracentrifugation of the crude extract at 145,000 x g, various layers were found in the gradient. One yellow layer showed enzymatic conversion of PCP. One chloride ion was released per molecule of PCP. The product of the enzymatic conversion was tetrachlorohydroquinone. NADPH and oxygen were essential for this reaction. EDTA stimulated the enzymatic activity by 67%. The optimum pH for the enzyme activity was 7.5, and the temperature optimum was 25 degrees C. Enzymatic activity was also detected with 2,4,5-trichlorophenol, 2,3,4-trichlorophenol, 2,4,6-trichlorophenol, and 2,3,4,5-tetrachlorophenol as substrates, whereas 3,4,5-trichlorophenol, 2,4-dichlorophenol, 3,4-dichlorophenol, and 4-chlorophenol did not serve as substrates.     

Prevalence of fungi in carpeted floor environment: Analysis of dust samples from living-rooms,bedrooms, offices and school classrooms

The results of 100 carpet dust analyses from atopic individuals' environment were compared according to the sampling period or the location. Dust samples were collected with a standard domestic vacuum cleaner, in locations with carpeted floor: in residences (living-room and/or bedroom), in school classrooms and in offices. The quantities of fungi vary from 5000 CFU/g to 66 000 000 CFU/g of dust. More than 100 species were isolated by dilution plating. The main species found in carpet dust wereEurotium repens, Penicillium chrysogenum, Alternaria alternata, Aureobasidium pullulans andPhoma herbarum. Strict xerophilic species were rather rare and detected in small quantities. Differences in the distribution of the CFU concentrations were examined for the four different sampling locations and were statistically significant (P=0.0174). In this study, schools were open spaces, and offices, mostly with air conditioning systems, were locations in which air is not confined. This, added to frequent professional carpet cleaning, probably explains the lowest levels of fungal concentration found in these locations. The majority of the homes had the largest fungal concentration in the living-room (median: 2×10⁵ CFU/g) while some bedrooms (median: 7×10⁴ CFU/g) had the highest concentrations. It is suggested that, when fungi are suspected to be the origin of respiratory allergy or irritating symptoms, the mycoflora of the bedroom, principally, should be investigated first.     

Prevalence of fungi in carpeted floor environment: analysis of dust samples from living-rooms,bedrooms, offices and school classrooms

The results of 100 carpet dust analyses from atopic individuals' environment were compared according to the sampling period or the location. Dust samples were collected with a standard domestic vacuum cleaner, in locations with carpeted floor: in residences (living-room and/or bedroom), in school classrooms and in offices. The quantities of fungi vary from 5000 CFU/g to 66 000 000 CFU/g of dust. More than 100 species were isolated by dilution plating. The main species found in carpet dust wereEurotium repens, Penicillium chrysogenum, Alternaria alternata, Aureobasidium pullulans andPhoma herbarum. Strict xerophilic species were rather rare and detected in small quantities. Differences in the distribution of the CFU concentrations were examined for the four different sampling locations and were statistically significant (P=0.0174). In this study, schools were open spaces, and offices, mostly with air conditioning systems, were locations in which air is not confined. This, added to frequent professional carpet cleaning, probably explains the lowest levels of fungal concentration found in these locations. The majority of the homes had the largest fungal concentration in the living-room (median: 2×10⁵ CFU/g) while some bedrooms (median: 7×10⁴ CFU/g) had the highest concentrations. It is suggested that, when fungi are suspected to be the origin of respiratory allergy or irritating symptoms, the mycoflora of the bedroom, principally, should be investigated first.     

Subcellular distribution of carbonic anhydrase in Solanum tuberosum L. leaves

The intracellular compartmentation of carbonic anhydrase (CA; EC 4.2.1.1), an enzyme that catalyses the reversible hydration of CO₂ to bicarbonate, has been investigated in potato (Solanum tuberosum L.) leaves. Although enzyme activity was mainly located in chloroplasts (87% of total cellular activity), significant activity (13%) was also found in the cytosol. The corresponding CA isoforms were purified either from chloroplasts or crude leaf extracts, respectively. The cytosolic isoenzyme has a molecular mass of 255 000 and is composed of eight identical subunits with an estimated M _r of 30000. The chloroplastic isoenzyme (M _r 220000) is also an octamer composed of two different subunits with M _r estimated at 27 000 and 27 500, respectively. The N-terminal amino acid sequences of both chloroplastic CA subunits demonstrated that they were identical except that the M _r-27 000 subunit was three amino acids shorter than that of the M _r-27 500 subunit. Cytosolic and chloroplastic CA isoenzymes were found to be similarly inhibited by monovalent anions (Cl^–, I^–, N ₃ ^- and NO ₃ ^- ) and by sulfonamides (ethoxyzolamide and acetozolamide). Both CA isoforms were found to be dependent on a reducing agent such as cysteine or dithiothreitol in order to retain the catalytic activity, but 2-mercaptoethanol was found to be a potent inhibitor. A polyclonal antibody directed against a synthetic peptide corresponding to the N-terminal amino acid sequence of the chloroplastic CA monomers also recognized the cytosolic CA isoform. This antibody was used for immunocytolocalization experiments which confirmed the intracellular compartmentation of CA: within chloroplasts, CA is restricted to the stroma and appears randomly distributed in the cytosol.Abbreviations BSA bovine serum albumin - CA carbonic anhydrase - PMSF phenylmethylsulphonyl fluoride - BAM benzamidine - DTT dithiothreitol - 2-ME 2-mercaptoethanol - PVDF polyvinylidene difluoride The authors thanks P. Carrier and Dr. B. Dimon for technical assistance with the mass-spectrometry measurements.