Novel highly emissive non-proteinogenic amino acids: synthesis of 1,3,4-thiadiazolyl asparagines and evaluation as fluorimetric chemosensors for biologically relevant transition metal cations

Highly emissive heterocyclic asparagine derivatives bearing a 1,3,4-thiadiazolyl unit at the side chain, functionalised with electron donor or acceptor groups, were synthesised and evaluated as amino acid-based fluorimetric chemosensors for metal cations, such as Cu²⁺, Zn²⁺, Co²⁺ and Ni²⁺. The results suggest that there is a strong interaction through the donor heteroatoms at the side chain of the various asparagine derivatives, with high sensitivity towards Cu²⁺ in a ligand–metal complex with 1:2 stoichiometry. Association constants and detection limits for Cu²⁺ were calculated. The photophysical and metal ion sensing properties of these asparagine derivatives confirm their potential as fluorimetric chemosensors and suggest that they can be suitable for incorporation into chemosensory peptidic frameworks.     

Different Effects of Transgenic Maize and Nontransgenic Maize on Nitrogen-Transforming Archaea and Bacteria in Tropical Soils

The composition of the rhizosphere microbiome is a result of interactions between plant roots, soil, and environmental conditions. The impact of genetic variation in plant species on the composition of the root-associated microbiota remains poorly understood. This study assessed the abundances and structures of nitrogen-transforming (ammonia-oxidizing) archaea and bacteria as well as nitrogen-fixing bacteria driven by genetic modification of their maize host plants. The data show that significant changes in the abundances (revealed by quantitative PCR) of ammonia-oxidizing bacterial and archaeal communities occurred as a result of the maize host being genetically modified. In contrast, the structures of the total communities (determined by PCR-denaturing gradient gel electrophoresis) were mainly driven by factors such as soil type and season and not by plant genotype. Thus, the abundances of ammonia-oxidizing bacterial and archaeal communities but not structures of those communities were revealed to be responsive to changes in maize genotype, allowing the suggestion that community abundances should be explored as candidate bioindicators for monitoring the possible impacts of cultivation of genetically modified plants.     

DNMT3B C46359T and SHMT1 C1420T polymorphisms in the folate pathway in carcinogenesis of head and neck

Folate is an essential nutrient with important roles in the synthesis, repair, and DNA methylation. Polymorphisms in genes encoding enzymes involved in folate metabolism can change these processes and modulate cancer development. We investigated DNMT3B C46359T (rs2424913) and SHMT1 C1420T (rs1979277) polymorphisms related to folate pathway in head and neck cancer (HNC) risk and the association of the disease with gender, risk factors and clinical histopathological parameters. A case–control study was conducted in 725 individuals (237 patients with HNC and 488 control individuals). Real-time PCR technique was performed for genotyping. Chi square and multiple logistic regression tests were used for statistical analysis. Male gender (OR 1.80; 95 % CI 1.11–2.94; P < 0.02) and tobacco consumption (OR 6.14; 95 % CI 4.13–9.13; P < 0.001) were associated with increased risk for this neoplasia. There were no significant associations between the polymorphisms and risk of disease, however, the tobacco and alcohol habits together showed association with SHMT1 C1420T polymorphism (OR 1.48; 95 % CI 1.08–2.03; P = 0.014). SHMT1 C1420T polymorphism was associated with larynx tumor (OR 0.48; 95 % CI 0.27–0.86; P < 0.05). In conclusion, tobacco habit and male gender can be predictors for HNC risk. SHMT1 C1420T and DNMT3B C46359T polymorphisms are not associated with HNC development in Brazilian population, however, SHMT1 C1420T polymorphism is less frequent in patients with primary site of tumor in larynx and more frequent in individuals who consume tobacco and alcohol together. Further studies involving gene–gene interactions in folate pathway in different populations can contribute to the understanding of the polymorphisms effect on HNC risk.     

The CryoCapsule: Simplifying Correlative Light to Electron Microscopy

Correlating complementary multiple scale images of the same object is a straightforward means to decipher biological processes. Light microscopy and electron microscopy are the most commonly used imaging techniques, yet despite their complementarity, the experimental procedures available to correlate them are technically complex. We designed and manufactured a new device adapted to many biological specimens, the CryoCapsule, that simplifies the multiple sample preparation steps, which at present separate live cell fluorescence imaging from contextual high‐resolution electron microscopy, thus opening new strategies for full correlative light to electron microscopy. We tested the biological application of this highly optimized tool on three different specimens: the in vitro Xenopus laevis mitotic spindle, melanoma cells over‐expressing YFP‐langerin sequestered in organized membranous subcellular organelles and a pigmented melanocytic cell in which the endosomal system was labeled with internalized fluorescent transferrin.      

Performance and microbial communities of a continuous stirred tank anaerobic reactor treating two-phases olive mill solid wastes at low organic loading rates

A study of the performance and microbial communities of a continuous stirred tank reactor (CSTR) treating two-phases olive mill solid wastes (OMSW) was carried out at laboratory-scale. The reactor operated at a mesophilic temperature (35 degrees C) and an influent substrate concentration of 162 g total chemical oxygen demand (COD)L(-1) and 126 g volatile solids (VS)L(-1). The data analyzed in this work corresponded to a range of organic loading rates (OLR) of between 0.75 and 3.00 g CODL(-1)d(-1), getting removal efficiencies in the range of 97.0-95.6%. Methane production rate increased from 0.164 to 0.659 L CH(4)L(reactor)(-1)d(-1) when the OLR increased within the tested range. Methane yield coefficients were 0.225 L CH(4)g(-1) COD removed and 0.290 L CH(4)g(-1) VS removed and were virtually independent of the OLR applied. A molecular characterization of the microbial communities involved in the process was also accomplished. Molecular identification of microbial species was performed by PCR amplification of 16S ribosomal RNA genes, denaturing gradient gel electrophoresis (DGGE), cloning and sequencing. Among the predominant microorganisms in the bioreactor, the Firmicutes (mainly represented by Clostridiales) were the most abundant group, followed by the Chloroflexi and the Gamma-Proteobacteria (Pseudomonas species as the major representative). Other bacterial groups detected in the bioreactor were the Actinobacteria, Bacteroidetes and Deferribacteres. Among the Archaea, the methanogen Methanosaeta concilii was the most representative species.     

BLOC-1 interacts with BLOC-2 and the AP-3 complex to facilitate protein trafficking on endosomes

The adaptor protein (AP)-3 complex is a component of the cellular machinery that controls protein sorting from endosomes to lysosomes and specialized related organelles such as melanosomes. Mutations in an AP-3 subunit underlie a form of Hermansky-Pudlak syndrome (HPS), a disorder characterized by abnormalities in lysosome-related organelles. HPS in humans can also be caused by mutations in genes encoding subunits of three complexes of unclear function, named biogenesis of lysosome-related organelles complex (BLOC)-1, -2, and -3. Here, we report that BLOC-1 interacts physically and functionally with AP-3 to facilitate the trafficking of a known AP-3 cargo, CD63, and of tyrosinase-related protein 1 (Tyrp1), a melanosomal membrane protein previously thought to traffic only independently of AP-3. BLOC-1 also interacts with BLOC-2 to facilitate Tyrp1 trafficking by a mechanism apparently independent of AP-3 function. Both BLOC-1 and -2 localize mainly to early endosome-associated tubules as determined by immunoelectron microscopy. These findings support the idea that BLOC-1 and -2 represent hitherto unknown components of the endosomal protein trafficking machinery.     

Mathematical modelling of the aerobic degradation of two-phase olive mill effluents in a batch reactor

A laboratory-scale study was conducted on the aerobic degradation of two-phase olive mill effluents (TPOME) made up of the mixture of the washwaters derived from the initial cleansing of the olives and those obtained in the washing and purification of virgin olive oil. The process was carried out in a 1-l working volume stirred tank reactor operating in batch mode at room temperature (25 °C). The reactor was operated at influent substrate concentrations of 2.80 g COD/l (TPOME 25%), 5.45 g COD/l (TPOME 50%), 8.18 g COD/l (TPOME 75%) and 10.90 g COD/l (TPOME 100%). After five days of operation time, total and soluble COD removal efficiencies of 64.3% and 66.6% were achieved respectively for the most concentrated influent used (TPOME 100%). A simplified kinetic model for studying the hydrolysis of insoluble organic matter, oxidation of soluble substrate and biomass production was proposed on the basis of the experimental results obtained. The following kinetic constants with their standard deviations were obtained for the above stages in the case of the most concentrated influent used (TPOME 100%): k₁ (kinetic constant for hydrolysis of suspended organic matter): 0.11 ± 0.01 l/(g VSS day); k₂ (kinetic constant for total consumption of soluble substrate): 0.30 ± 0.02 l/(g VSS day); k₃ (endogenous metabolism constant): 0.07 ± 0.01 per day). Finally, the biomass yield coefficient was found to be 0.30 g VSS/g COD_removed. The values of non-biodegradable total and soluble CODs obtained from the model were found to be 3 and 2 g/l, respectively. The kinetic constants obtained and the proposed equations were used to simulate the aerobic degradation process of TPOME and to obtain the theoretical values of non-soluble and soluble CODs and biomass concentration. The small deviations obtained (equal or lower than 10%) between the theoretical and experimental values suggest that the parameters obtained represent and predict the activity of the microorganisms involved in the overall aerobic degradation process of this wastewater.     

AP-1 and KIF13A coordinate endosomal sorting and positioning during melanosome biogenesis

Specialized cell types exploit endosomal trafficking to deliver protein cargoes to cell type–specific lysosome-related organelles (LROs), but how endosomes are specified for this function is not known. In this study, we show that the clathrin adaptor AP-1 and the kinesin motor KIF13A together create peripheral recycling endosomal subdomains in melanocytes required for cargo delivery to maturing melanosomes. In cells depleted of AP-1 or KIF13A, a subpopulation of recycling endosomes redistributes to pericentriolar clusters, resulting in sequestration of melanosomal enzymes like Tyrp1 in vacuolar endosomes and consequent inhibition of melanin synthesis and melanosome maturation. Immunocytochemistry, live cell imaging, and electron tomography reveal AP-1– and KIF13A-dependent dynamic close appositions and continuities between peripheral endosomal tubules and melanosomes. Our results reveal that LRO protein sorting is coupled to cell type–specific positioning of endosomes that facilitate endosome–LRO contacts and are required for organelle maturation.