Nitrogenase activity associated with codium species from New Zealand marine habitats

Nitrogenase activity, measured as acetylene reduction, was recorded at rates up to 1028 nmol.h \g * dry weight for Codium adhaerens (Cabr.) Ag. var. convolutum Dellow and Codium fragile (Sur.) Hariot subsp. tomentosoides (Van Goor) Silva collected from New Zealand habitats. In both species the ability to reduce acetylene is invariably associated with the presence of a heterocystous blue-green alga, Calothrix sp., epiphytic or embedded in the Codium thallus. A highly significant (P < 0.001) correlation between heterocyst frequency and nitrogenase activity was found. Nitrogenase and net photosynthesis of the Codium-Calothrix system have different steady-state responses to light intensity, and the kinetics of the two processes also differ in that nitrogenase is slow to respond to illumination or darkening. Glucose additions to Codium did not significantly increase nitrogenase activity. Nitrogenase is relatively insensitive to oxygen tension over the range 0-1.0 atm (0-1.033 kgf.cnT2) and still occurs at 1.5 atm (1.55 kgf.cm"2); this condition is unique in all nitrogenase systems thus far reported. Collectively these facts suggest that Calothrix is the agent primarily responsible for nitrogenase activity in these Codium species

Comparison of different methods for release of Bifidobacterium longum Bb46 from the poly(vinylpyrrolidone)-poly(vinylacetate-co-crotonic acid) interpolymer complex matrix, and the effect of grinding on the microparticles

Bifidobacteria have been efficiently encapsulated in poly(vinylpyrrolidone)-poly(vinylacetate-co-crotonic acid) (PVP:PVAc-CA) interpolymer complex formed in scCO2. Research indicated that this method improves the stability of encapsulated bacteria in simulated gastrointestinal fluids in vitro. However, further analysis indicated release of lower numbers of encapsulated bacteria from the encapsulating matrix. The aims of this study were to determine a method that would release high numbers of bacteria from the PVP:PVAc-CA interpolymer complex matrix microparticles, and furthermore, to determine the effects of milling on the morphological properties of the microparticles. Three release methods, namely sonication, homogenization in a stomacher and incubation in simulated intestinal fluid (SIF) were compared. Released viable bacteria were assayed using plate counts. Viable bacteria released using a stomacher were three orders of magnitude higher than those released by incubation and an order of magnitude higher than those released using sonication. SEM indicated no negative effects such as exposure of encapsulated bacteria on the matrix due to milling of product. Homogenization in a stomacher is the most efficient method for releasing bacteria from the PVP:PVAc-CA interpolymer complex matrix. Particle size of the PVP:PVAc-CA microparticles encapsulating bacteria can be reduced further by grinding, without exposing the enclosed bacteria.The authors would like to thank the National Research Foundation of South Africa for funding of the project.http://www.springer.com/chemistry/biotech/journal/1127

A Preliminary Studies of Fish Richness in the Tondano River Estuary Manado Bay

The purpose of this study was to analyze the richness of fish species in the Tondano River estuary. Sampling was done for two months, in July and August 2022, new moon phase, during the low tide at 13.00-16.00 pm.&nbsp; Sampling used a 20-m beach seine with a cod-end part of 0.2-cm mesh and wings of 2-m height and 1.5-cm mesh.&nbsp; The beach seine was operated 10 times starting from the lowest tide at 13.00 pm to the tide condition at 16.00 pm. As a whole, 736&nbsp; individuals were caught, consisting of 24 species and 17 families, 14 migrant species, and 10 resident species&nbsp;&nbsp; The number of fish varied from 1 to 445 individuals,&nbsp; in which Terapon jarbua (445 ind) was the most abundant, followed by Neovespicula depressifrons (70 ind). The dominant index&nbsp; (C) was 0.38 and the diversity index (H) was 1.65.&nbsp; The resident species were 120 individuals varying from 2 to 70 ind., and the most abundant was&nbsp;&nbsp; Neovespicula depressifrons (70 ind.). The dominant index (C) was 0.37 and the diversity index was 1.47.&nbsp

Motor praxiology: physical education as education of motor conducts

Objetivo:apresentar os principais conceitos da PraxiologiaMotriz e apontar a possibilidade de utilização dessa disciplina no âmbito da educação física escolar. Resultados e discussão: apraxiologia motriz ou ciência da ação motriz, idealizada pelo professor Pierre Parlebas, é uma disciplina científica que aporta evidênciascientíficas para o desenvolvimento de uma educação física inovadora, moderna e com reconhecimento científico. Os jogos, esportes e quaisquer outras manifestações motrizes possuem uma lógica interna (estrutura de funcionamento), que orienta os alunos a protagonizar diferentes tipos de relações.As diferentes relações caracterizam domínios de ação motriz muito específicos e proporcionam efeitos distintos nas dimensões humanas dos indivíduos, assim como aprendizadosmuito particulares. Conclusões:apartir desta perspectiva, a educação física é concebida como uma educaçãodas condutas motrizes e uma poderosa ferramenta para a educação integral do alunado.Objective: present the main concepts of motor praxiology and to point out the possibility of using this discipline within school physical education. Results and discussion:Motor Praxiology or motor action science, created by Professor Pierre Parlebas, is a scientific discipline that provides scientific evidence for the development of innovative, modern and scientifically recognizedphysical education. Games, sportsand other motor practices have an internal logic (operational structure), which guides students to play the different types of relationships. The different relationships characterize very specific domains of motor action and provide different effects on the human dimensions of individuals, as well as on very particular learning. Conclusion:From this perspective, physical education is conceived as an education of motor conducts and a powerful tool for the integral formation of students

Electrochemical Oxidation and Sensing of Methylamine Gas in Room Temperature Ionic Liquids

The electrochemical behaviour of methylamine gas in several room temperature ionic liquids (RTILs), [C2mim][NTf2], [C4mim][NTf2], [C6mim][FAP], [C4mpyrr][NTf2], [C4mim][BF4], and [C4mim][PF6] has been investigated on a Pt microelectrode using cyclic voltammetry. A broad oxidation wave at approximately 3 V, two reduction peaks and another oxidation peak was observed. A complicated mechanism is predicted based on the voltammetry obtained, with ammonia gas as a likely by-product. The currents obtained suggest that methylamine has a high solubility in RTILs, which is important for gas sensing applications. The analytical utility of methylamine was then studied in [C4mpyrr][NTf2] and [C2mim][NTf2]. A linear calibration graph with an R2 value of 0.99 and limits of detection of 33 and 34 ppm were obtained respectively, suggesting that RTILs are favourable non-volatile solvents for the electrochemical detection of highly toxic methylamine gas

Statistics of Magnetic Fields for OB Stars

Based on an analysis of the catalog of magnetic fields, we have investigated the statistical properties of the mean magnetic fields for OB stars. We show that the mean effective magnetic field ${\cal B}$ of a star can be used as a statistically significant characteristic of its magnetic field. No correlation has been found between the mean magnetic field strength ${\cal B}$ and projected rotational velocity of OB stars, which is consistent with the hypothesis about a fossil origin of the magnetic field. We have constructed the magnetic field distribution function for B stars, $F({\cal B})$, that has a power-law dependence on ${\cal B}$ with an exponent of $\approx -1.82$. We have found a sharp decrease in the function $F({\cal B})$F for {\cal B}\lem 400 G that may be related to rapid dissipation of weak stellar surface magnetic fields.Comment: 22 pages, 7 figures, accepted Astronomy Letters, 2010, vol.36, No.5, pp.370-379, contact E-mail: [email protected]

CoRoT high-precision photometry of the B0.5 IV star HD 51756

OB stars are important constituents for the ecology of the Universe, and there are only a few studies on their pulsational properties detailed enough to provide important feedback on current evolutionary models. Our goal is to analyse and interpret the behaviour present in the CoRoT light curve of the B0.5 IV star HD 51756 observed during the second long run of the space mission, and to determine the fundamental stellar parameters from ground-based spectroscopy gathered with the CORALIE and HARPS instruments after checking for signs of variability and binarity, thus making a step further in mapping the top of the Beta Cep instability strip. We compare the newly obtained high-resolution spectra with synthetic spectra of late O-type and early B-type stars computed on a grid of stellar parameters. We match the results with evolutionary tracks to estimate stellar parameters. We use various time series analysis tools to explore the nature of the variations present in the light curve. Additional calculations are carried out based on distance and historical position measurements of the components to impose constraints on the binary orbit. We find that HD 51756 is a wide binary with both a slow (v sin i \approx 28 km s^-1) and a fast (v sin i \approx 170 km s^-1) early-B rotator whose atmospheric parameters are similar (T_eff \approx 30000 K and log g \approx 3.75). We are unable to detect pulsation in any of the components, and we interpret the harmonic structure in the frequency spectrum as sign of rotational modulation, which is compatible with the observed and deduced stellar parameters of both components. The non-detection of pulsation modes provides a feedback on the theoretical treatment, given that non-adiabatic computations applied to appropriate stellar models predict the excitation of both pressure and gravity modes for the fundamental parameters of this star.Comment: Accepted for publication in Astronomy and Astrophysics on 14/01/2011, 11 pages, 9 figures, 4 table

Accelerating surveillance and research of antimicrobial resistance - an online repository for sharing of antimicrobial susceptibility data associated with whole-genome sequences

Antimicrobial resistance (AMR) is an emerging threat to modern medicine. Improved diagnostics and surveillance of resistant bacteria require the development of next-generation analysis tools and collabor