Determination of the basicity of Mannich ketones by capillary electrophoresis

Capillary electrophoretic (CE) method to characterise Mannich ketones (MKs) containing morpholine moiety was developed. Basicity (pKa,exp) of the MKs was characterised by measured data derived from the electrophoretic mobility values obtained in the CE separation. The MKs were found to be weaker bases than the parent morpholine molecule itself and the experimentally determined basicity values proved to be dependent on the chemical structure of the MKs. Since the basicity of the MKs has an influence on their reactivity and biological activity it seems to be useful to determine experimentally the pKa,exp values of the newly synthesised compounds to support rational drug design or screening of the molecule libraries.     

Ultrastructure of neuropeptide-Y immunoreactive elements in the superior colliculus of cat

Whereas the presence of neuropeptide-Y (NPY) in the superior colliculus (SC) has been established, its participation in the ultrastructural organisation of the neuronal networks in the SC has not been studied. Accordingly, in the present paper light and electron microscopic NPY immunohistochemical studies were performed on the SC of cat. NPY fibres were found to be present predominantly in the superficial grey layer (SGL) of the SC, though a few small NPY cells were found in both the deeper and the upper layers. Ultrastructural observations revealed that the NPY nerve endings establish almost exclusively axo-dendritic synaptic contacts in the SGL of the SC. Thus, the presumably inhibitory impact of the NPY terminals is exerted through the dendrites of the SGL neurons, and not directly to the retinal axons, as thought previously.     

Ecophysiology and breeding of mycoparasitic Trichoderma strains (a review)

Losses due to plant diseases may be as high as 10-20% of the total worldwide food production every year, resulting in economic losses amounting to many billions of dollars and diminished food supplies. Chemical control involves the use of chemical pesticides to eradicate or reduce the populations of pathogens or to protect the plants from infection by pathogens. For some diseases chemical control is very effective, but it is often non-specific in its effects, killing beneficial organisms as well as pathogens, and it may have undesirable health, safety, and environmental risks. Biological control involves the use of one or more biological organisms to control the pathogens or diseases. Biological control is more specialized and uses specific microorganisms that attack or interfere with the pathogens. The members of the genus Trichoderma are very promising against soil-born plant parasitic fungi. These filamentous fungi are very widespread in nature, with high population densities in soils and plant litters [1]. They are saprophytic, quickly growing and easy to culture and they can produce large amounts of conidia with long lifetime.     

Application of the maximum entropy method to absorption kinetic rate processes

The maximum entropy method, originally developed for astronomical image restoration, has already been successfully applied to a variety of biophysical problems. Through numerical inverse Laplace transformation, the method determines the lifetime distribution function with the largest informational entropy. Starting from a flat distribution, it results in the consistent selection of a single distribution from the numerous possible ones that correctly fit the data. In this paper, we discuss the application of the method to kinetic processes that have both rise and decay components, and test the algorithm with different signal to noise ratio generated data. It is proved that the mass conservation constraint can be taken into account by reducing the search to a lower dimensional subspace. The effect of noise on the width of lifetime distribution is studied and it is shown that an inherent entropy connected to the underlying kinetics can be separated from the noise generated entropy. The possibility of the application of the method to the photocycle kinetics of bacteriorhodopsin is also shown.     

Terminal electron transport system (ETS)-activity in the sediment of Lake Balaton,Hungary

Terminal electron transport system (ETS)-activity of the sediment and plankton of Lake Balaton, the largest shallow lake of Central Europe was measured by tetrazolium-reduction biweekly during 1989–1990 and in the spring of 1991. Sediment proved to be enzymatically active to 30-35 cm down in the hypertrophic Keszthely Bay and to 15–20 cm down in the meso-eutrophic Siófok Basin. Sediment ETS-activity exceeded planktonic activity 15 to 24 fold.The total activity m^–2 showed one or two order of magnitude higher respiratory potential in Lake Balaton than needed for complete oxidation of the planktonic primary production; most of this potential was detected in the upper 3–5 cm sediment layer in springs. Incubations of cell-free homogenates of sediment bacteria showed that ETS remains active days after death of organisms at low temperature. Accumulated postmortem ETS-activity derived from the benthic diatoms, bacteria, plankton deposit and dead summer macrophytes seems to be responsible for the high ETS-activity of the sediment in the warming periods in springs. These enzyme fractions may contribute to the rapid oxidation of the alkaline, well-aerated lake.     

Isolating the influence of ontogeny helps predict island-wide variability in fish otolith chemistry

Reviews in Fish Biology and Fisheries - For marine fishes of commercial interest, defining how individuals vary in certain attributes, through ontogeny, and across space and time, can help expose...