Apple tissue culture contamination by <Emphasis Type="Italic">Rhodotorula</Emphasis> spp.: Identification and prevention

Summary Shool cultures of apple cv. Pinova were contaminated with faint pink pigmented yeast. Yeast isolates were identified as Rhodotorula slooffiae with standard physiological methods and molecular analysis. Growth of isolated yeasts was tested against different fungicides. The following fungicides inhibited the growth of yeast isolates, and were not phytotoxic to apple shoots at concentrations lower than the minimal phytotoxic concentrations (MPC): ProClin^? 300, mancozeb, triforine, myclobutanil, thiabendazole, mancozeb+zoxamid, and silver nitrate. Some fungicides inhibited growth of yeasts, but were phytotoxic. These included miconazole, PPM^™, copper sulfate, potassium sorbate, and cycloheximide. Benomyl was not phytotoxic, but was effective only at high doses. Decontamination of shoots was achieved using a combination of two treatments. Shoots were first soaked in half-strength Murashige and Skoog (MS) liquid medium containing silver nitrate (588μM) and Silvet 77 (0.01%) for 1–2h, and then transferred to a solidified MS medium containing both mancozeb (15mgl⁻¹) and thiabendazole (40mgl⁻¹).     

Enzymatic grafting of chitosan onto Bombyx mori silk fibroin: kinetic and IR vibrational studies

The potential for using tyrosinase to graft the polysaccharide chitosan (Ch) onto Bombyx mori silk fibroin (SF) was examined. FT-IR spectroscopy coupled to HPLC amino acid analysis showed that mushroom tyrosinase (MT) catalyses the oxidation of tyrosine (Tyr) of SF to electrophilic o-quinones. Kinetic studies showed that only a fraction of the Tyr residues available on the SF chain were oxidized. This result was interpreted in the light of the structure assumed by SF in aqueous solution: Tyr aromatic side chain groups buried into the folded hydrophobic portions of the chain were probably less accessible to MT for steric reasons. Using slightly acidic conditions (pH 6), it was possible to modify SF under homogeneous conditions. FT-IR spectroscopy provided evidence that Ch was grafted onto MT-oxidized SF: the o-quinones were found to undergo a subsequent non-enzymatic reaction with nucleophilic amino groups of Ch via Schiff-base and Michael addition mechanisms. Various factors, i.e. reaction time, pH, MT/SF ratio, were found to influence the grafting yield. The highest grafting yield was achieved at pH 7, i.e. more favorable to MT activity rather than to Ch solubility, suggesting that the determining step of the grafting reaction is the formation of o-quinones. The FT-IR spectroscopy revealed that grafting induced a beta-sheet --> random coil conformational transition.     

Conformational features of cepacian: the exopolysaccharide produced by clinical strains of Burkholderia cepacia

Conformational energy calculations and molecular dynamics investigations, both in water and in dimethyl sulfoxide, were carried out on the exopolysaccharide cepacian produced by the majority of the clinical strains of Burkholderia cepacia, an opportunistic pathogen causing serious lung infection in patients affected by cystic fibrosis, The investigation was aimed at defining the structural and conformational features, which might be relevant for clarification of the structure-function relationships of the polymer. The molecular dynamics calculations were carried out by Ramachandran-type energy plots of the disaccharides that constitute the polymer repeating unit. The dynamics of an oligomer composed of three repeating units were investigated in water and in Me2SO, a non-aggregating solvent. Analysis of the time persistence of hydrogen bonds showed the presence of a large number of favourable interactions in water, which were less evident in Me2SO. The calculations on the cepacian chain indicated that polymer conformational features in water were affected by the lateral chains, but were also largely dictated by the presence of solvent. Moreover, the large number of intra-chain hydrogen bonds in water disappeared in Me2SO solution, increasing the average dimension of the polymer chains.     

Phosphotransferase-mediated transport of the osmolyte 2-O-alpha-mannosyl-D-glycerate in Escherichia coli occurs by the product of the mngA (hrsA) gene and is regulated by the mngR (farR) gene product acting as repressor

2-O-alpha-mannosyl-D-glycerate (MGs) has been recognized as an osmolyte in hyperthermophilic but not mesophilic prokaryotes. We report that MG is taken up and utilized as sole carbon source by Escherichia coli K12, strainMC4100. Uptake is mediated by the P-enolpyruvate-dependent phosphotransferase system with the MG-inducible HrsA (now called MngA) protein as its specific EIIABC complex. The apparent Km of MG uptake in induced cells was 10 microm, and the Vmax was 0.65 nmol/min/10(9) cells. Inverted membrane vesicles harboring plasmid-encoded MngA phosphorylated MG in a P-enolpyruvate-dependent manner. A deletion mutant in mngA was devoid of MG transport but is complemented by a plasmid harboring mngA. Uptake of MG in MC4100 also caused induction of a regulon specifying the uptake and the metabolism of galactarate and glucarate controlled by the CdaR activator. The ybgG gene (now called mngB) the gene immediately downstream of mngA encodes a protein with alpha-mannosidase activity. farR, the gene upstream of mngA (now called mngR) had previously been characterized as a fatty acyl-responsive regulator; however, deletion of mngR resulted in the up-regulation of only two genes, mngA and mngB. The mngR deletion caused constitutive MG transport that became MG-inducible after transformation with plasmid expressed mngR. Thus, MngR is the regulator (repressor) of the MG transport/metabolism system. Thus, the mngR mngA mngB gene cluster encodes an MG utilizing system.     

Purification of a thermostable antinociceptive lectin isolated from Andira anthelmia

Andira anthelmia (tribe Dalbergieae), a plant from Brazilian Amazon, possesses a seed lectin that was purified by affinity chromatography in sepharose–mannose. This novel Dalbergieae lectin, named AAL, agglutinated rabbit erythrocytes treated with trypsin. The hemagglutinating activity of AAL was maintained after incubation at a wide range of temperature (40 to 70 °C) and pH, was shown to be dependent on divalent cations, and was inhibited by d ‐mannose and d ‐sucrose. AAL showed an electrophoretic profile in sodium dodecyl sulfate–polyacrylamide gel electrophoresis similar to other lectins of the tribe Dalbergieae, presenting a double band of molecular weight with approximately 20 kDa and other minor bands of 17, 15, and 13 kDa, being the smaller fragment glycosylated. AAL injected by intravenous route in mice showed antinociceptive activity in two behavioral tests (writhing and formalin). In the writhing test induced by acetic acid, AAL showed inhibitory effect at 0.01 mg/kg (68%), 0.1 mg/kg (46%) and 1 mg/kg (74%). In the formalin test, AAL (0.1 mg/kg) inhibited by 48% the licking time in the inflammatory phase, an effect that was recovered by the lectin association with mannose. In conclusion, AAL presents analgesic effect involving the lectin domain via peripheral mechanisms of inflammatory nociception. This activity highlights the importance of lectins as tools to be used for understanding the interaction of protein–carbohydrate in processes associated to inflammatory pain. Copyright © 2015 John Wiley & Sons, Ltd.     

New insights into the distribution and conservation status of the Golden-White Tassel-Ear Marmoset <Emphasis Type="Italic">Mico chrysoleucos</Emphasis> (Primates,Callitrichidae)

Among the 13 Mico species recognized by the IUCN Red List of Threatened Species, six are listed as “Data Deficient”. The geographic range of most of the Mico species has been estimated from only a few records. We report new localities and the geographic extension of Mico chrysoleucos. In addition, we confirmed the presence of the species in two distinct protected areas. We modeled the habitat suitability of M. chrysoleucos using the maximum entropy method and including new records obtained by the authors in the state of Amazonas, Brazil. From the total area of occurrence calculated for the species, 22.8% is covered by protected areas and indigenous lands. The annual mean deforestation rate estimated between 2000 and 2015 was 2.95%, and the total area deforested by 2015 was 3354 km² or 8.6% of the total distribution limits of the species. The habitat lost between 2000 and 2015 was 3.2% (1131 km²) of the total potential distribution, while the habitat loss area legally protected was 31 km², and the habitat loss in settlements was equal to 691 km². Our results extend the geographic distribution of the species about 100 km farther south, with the Maracanã River being a possible geographic barrier for the species. The significantly low rate of habitat loss inside protected areas and indigenous land, when compared to unprotected areas, points out the importance of these areas to M. chrysoleucos conservation. The species is relatively wide-ranging, legally protected, and resilient to regional anthropic threats. However, the hydroelectric schemes and the improvement of the road system in southern Amazonia pose an imminent threat to the species.     

Length‐weight relationships of six fish species from São Marcos Bay,Northeastern Brazil

Length‐weight relationship parameters were calculated for six fish species from São Marcos Bay, in Northeast Brazil (the segment between 02°35′55″S and 44°20′58″W; 02°34′53″S and 44°21′48″W; 02º42′25″S and 44º26′46″W). The specimens were caught quarterly from April 2010 to February 2013, using monofilament gillnets (2, 4 and 6 cm between knots) from 100 m to 3,000 m long and 4 m to 6 m high. The present study covers a much wider size range for four species and adds new information for the maximum length of Notarius bonillai.     

Effect of monensin on the sulfation of heparan sulfate proteoglycan from endothelial cells.

Monensin is a monovalent metal ionophore that affects the intracellular translocation of secretory proteins at the level of trans-Golgi cisternae. Exposure of endothelial cells to monensin results in the synthesis of heparan sulfate and chondroitin sulfate with a lower degree of sulfation. The inhibition is dose dependent and affects the ratio [35S]-sulfate/[3H]-hexosamine of heparan sulfate from both cells and medium, with no changes in their molecular weight. By the use of several degradative enzymes (heparitinases, glycuronidase, and sulfatases) the fine structure of the heparan sulfate synthesized by control and monensin-treated cells was investigated. The results have shown that among the six heparan sulfate disaccharides there is a specific decrease of the ones bearing a sulfate ester at the 6-position of the glucosamine moiety. All other biosynthetic steps were not affected by monensin. The results are indicative that monensin affects the hexosamine C-6 sulfation, and that this sterification is the last step of the heparan sulfate biosynthesis and should occur at the trans-Golgi compartment.     

Cardiac growth in staged human fetuses: an allometric approach

The human cardiac growth was studied on 30 staged fetuses (gestational age ranged from 10 to 38 weeks post conception, WPC). The hearts were quantitatively evaluated considering their weight and the following linear parameters: the pulmonary (da.p.) and aortic (dA) internal diameters, the right (VR) and left (VL) ventricular wall thickness, the ventricular width (dV), and the length "sulcus terminalis-apex cordis" (Lst-apex). The data were correlated with the gestational age by using the allometric method (Y = bX alpha). The equations and the growth curves are presented. In the fetal life, we observe that the body weight is 134 times larger than the heart weight, the Lst-apex is 1.07 times larger than the dV, the da.p. is 1.50 times larger than the dA, and the VL is 1.19 times larger than the VR.