Phytochrome-mediated effects on extracellular peroxidase activity, lignin content and bending resistance in etiolated Vicia faba epicotyls

Etiolated Vicia faba seedlings were exposed to continuous red light to investigate whether changes in extracellular peroxidase activity were correlated in time and localization with changes in extension growth and/or lignin content in the subapical region of the epicotyl. Continuous red light: (a) increased extracellular peroxidase activity after a lag of ca 0.5 h, followed by a maximum peak after 2.5 h due to slightly acidic isoforms (pI = 6–6.5, according to isoelectrofocusing gels), a minimum after 4 h and a second maximum after 8 h due to acidic isoforms (pI=4–5), (b) increased lignin content and epicotyl resistance to bending after a lag of ca 4 h, i.e. simultaneously with changes in acidic extracellular peroxidase activity, and (c) reduced extension growth to a stable rate after a lag of ca 1 h, not coinciding with the kinetics of any of the extracellular peroxidase isoforms. These effects of continuous red light were at least partially mediated by phytochrome. Tissue printing and anatomical studies revealed red light effects on extracellular peroxidase activity and lignin content mainly in the outer cortical parenchyma. The results are consistent with the involvement of phyto-chrome-mediated effects on extracellular peroxidases (acidic isoforms) in the transduction chain leading to lignin responses to red light.     

Identification of a developmentally regulated sialidase inEimeria tenella that is immunologically related to theTrypanosoma cruzi enzyme

Sporozoites and merozoites of three species ofEimeria, E. tenella, E. maxima, andE. necatrix, that cause diarrhea in chickens worldwide, were examined for their expression of sialidase (SA) activity. The enzyme was found in three species, and the activity of merozoites was 10–20 times higher than that of sporozoites. The enzyme was resistant to degradation by proteases that are normally present in the intestine, a site inhabited by theEimeria parasites, and it was relatively resistant to heat, with optimum activity being at 40°C, which is within the range of temperature in the chicken intestine (40–43°C).E. tenella SA was immuniprecipitated by monoclonal and polyclonal antibodies raised against theTrypanosoma cruzi SA (TCSA), and enzyme activity was neutralized by these antibodies.E. tenella SA was identified by immunoblots as a doublet of molecular weight 190 000 and 180 000 using, as a probe, anti-TCSA antibodies and antibodies against a synthetic peptide (TR) derived from the long tandem repeat domain of TCSA. Binding of the monoclonal and polyclonal antibodies toE. tenella was completely blocked by TR, but not by an irrelevant peptide (BR). Therefore,E. tenella expresses a developmentally regulated SA that is structurally related to theT. cruzi counterpart. Because of the high SA activity in merozoites, and by analogy with other SA-producing microbes that inhabit mucin-rich epithelia, we suggest that theEimeria SA plays a role in desialylating intestinal mucins to reduce viscosity of the local environment and thereby facilitate parasite migration. The enzyme could also play a role in host cell-parasite interaction.Abbreviations SA sialidase (neuraminidase) - Neu5Ac N-acetylneuraminic acid - 4-MU-Neu5Ac 2-(4-methylumbelliferyl)--N-acetyl-d-neuraminic acid - BSA bovine serum albumin - PBS phosphate buffered saline - PMSF phenylmethylsulfonyl fluoride - PNA peanut agglutinin - Ab antibody - TCN-2 monoclonal antibody toT. cruzi sialidase, anti-Ars, monoclonal antibody top-azophenylarsonate - TCSA Trypanosoma cruzi sialidase     

Evaluation of Probiotic Properties of Novel Brazilian Lactiplantibacillus plantarum Strains

Probiotics and Antimicrobial Proteins - Beneficial effects of Lactiplantibacillus plantarum strains have been widely reported. Knowing that the effects of probiotic bacteria are strain-dependent,...     

Evaluation of coupling conditions for the incorporation of Nα-Fmoc-Tyr(PO3H2)-OH in solid-phase peptide synthesis

Summary In order to minimise the formation of the pyrophosphate derivative of the target peptide when side-chain-unprotected phopshotyrosine is used in solid-phase peptide synthesis, this building block can be incorporated using benzotriazolyloxy-tris-(dimethylamino)phosphonium hexafluorophosphate/1-hydroxybenzotriazole/N-methylmorpholine (1:1:2.3) in the presence of a chaotropic salt (0.4 M LiCl in N-methyl-2-pyrrolidinone).Abbreviations BOP benzotriazolyloxy-tris-(dimethylamino)phosphonium hexafluorophosphate - DIEA diisopropylethylamine - Fmoc 9-fluorenylmethoxycarbony - HATU N-[(dimethylamino)1H-1,2,3-triazolo[4,5-b]pyridin-1-ylmethylene]-N-methylmethan-aminium hexafluorophosphate N-oxide - HOBt 1-hydroxybenzotriazole - HPLC high-performance liquid chromatography - MALDI-TOF matrix-assisted laser-desorption ionization time-of-flight mass spectrometry - NMM N-methylmorpholine - NMP N-methyl-2-pyrrolidinone - Pmc 2,2,5,7,8-pentamethyl-chroman-6-sulfonyl - ® solid support - TFA trifluoroacetic acid - TPTU 2-(2-pyridon-1-yl)-1,1,3,3-tetramethyluroniumfluoroborate. Abbreviations used for amino acids follow the recommendations of the IUPAC-IUB Commission of Biochemical Nomenclature [Eur. J. Biochem., 138 (1984) 9]     

The vegetable rennet of Cynara cardunculus L. contains two proteinases with chymosin and pepsin-like specificities

The flowers of cardoon (genus Cynara) are traditionally used in Portugal for cheese making. In this work the vegetable rennet of the species Cynara cardunculus L. was characterized in terms of enzymic composition and proteolytic specificity of its proteinases (cardosin A and cardosin B). Cardosin A was found to cleave insulin B chain at the bonds Leu15-Tyr16, Leu17-Val18 and Phe25-Tyr26. In addition to the bonds mentioned cardosin B cleaves also Glu13-Ala14, Ala14-Leu15 and Phe24-Phe25 indicating that it has a broader specificity. The kinetic parameters for the hydrolysis of the synthetic peptide Leu-Ser-Phe(NO₂)-Nle-Ala-Leu-oMe were also determined and compared to those of chymosin and pepsin. The results obtained indicate that in terms of specificity and kinetic parameters cardosin A is similar to chymosin whereas cardosin B is similar to pepsin. It appears therefore that the enzyme composition of cardoon rennet closely resembles that of calf rennet.     

Batch culture of Candida utilis in a medium deprived of a phosphorous source

Summary Candida utilis var. major NRRL-Y-1084 was grown in a defined medium without a phosphorous (P) source. During the exponential phase, cells divided according to a specific growth rate of 0.32 h^-1, which is lower than the usual rate for a balanced medium (0.4–0.6 h^-1). The relative P content of the biomass decreased from 2.70% to 0.75% over a period of 6 h, including 2 h of cell division arrest. At the end of this period there was another interruption of cell division. After that, multiplication restarted at a considerably lower rate and it deviated slightly from the exponential pattern. The stationary phase began when biomass P content reached 0.4%–0.5%, slowly decreasing afterwards to 0.25–0.20%. Biomass synthesis was less affected than cell division by the relative decrease of endogenous P, the two processes differing partially in their kinetics. Cell lysis started shortly before the stationary phase and affected about 20% of the population by the end of the assay. RNA and P content of the resulting biomass were 2.4% and 0.25% respecitvely, P being mainly incorporated to RNA.The relationship of biomass production to glucose uptake was very low, probably because the marked P deficiency called for an increase in energy consumption for growth and specially for maintenance. Compared with yeasts grown in a balanced medium, 40% increase in glycogen was observed, whereas no mean changes in the content of cell wall carbohydrates (glucan and mannan) and that of true protein were found.Member of the Scientific Researcher's Career of the Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET). Agrentina     

Four new species of Apiotrichum isolated from decayed wood in the evergreen rainy Valdivian forest of southern Chile

Four unusual Apiotrichum, isolated from decayed wood of Eucryphia cordifolia Cav., Nothofagus obliqua (Mirb.) Blume, and Laurelia sempervirens Wein., one of which was also isolated from the intestinal tract of Scaptomyza multispinosa Malloch (Diptera), are described and illustrated. These species differ from all the accepted Apiotrichum species (1–3) to warrant their establishment as four new species: Apiotrichum eucryphiae, Apiotrichum osvaldii, Apiotrichum futronensis and Apiotrichum nothofagi.