The distinction of different types of cytochromes P-450 from the yeasts Candida tropicalis and Saccharomyces uvarum

The distinction between two types of cytochromes P-450 originating from microsomes of Candida tropicalis grown on glucose and on alkane was achieved. Criteria of differentiation between these two cytochrome P-450 forms were based on the characteristics of reduced carbon monoxide difference spectra, on substrate specificity, and on binding and inhibition kinetics of the fungistatic compound propiconazole. One cytochrome P-450 form catalyzed the 14 alpha-demethylation of lanosterol and bound propiconazole with an equimolar ratio. This form was present in microsomes from glucose-grown cells and shared similar characteristics with the cytochrome P-450 originating from Saccharomyces uvarum grown on the same carbon source. The other cytochrome P-450 form catalyzed the terminal hydroxylation of aliphatic hydrocarbons and showed a less specific binding ratio with propiconazole (10(3) mol propiconazole for 1 mol cytochrome P-450). This type of cytochrome P-450 was only present in the microsomes of C. tropicalis grown on alkane.     

Statistical analyses of repeated measures in physiological research: a tutorial

Experimental designs involving repeated measurements on experimental units are widely used in physiological research. Often, relatively many consecutive observations on each experimental unit are involved and the data may be quite nonlinear. Yet evidently, one of the most commonly used statistical methods for dealing with such data sets in physiological research is the repeated-measurements ANOVA model. The problem herewith is that it is not well suited for data sets with many consecutive measurements; it does not deal with nonlinear features of the data, and the interpretability of the model may be low. The use of inappropriate statistical models increases the likelihood of drawing wrong conclusions. The aim of this article is to illustrate, for a reasonably typical repeated-measurements data set, how fundamental assumptions of the repeated-measurements ANOVA model are inappropriate and how researchers may benefit from adopting different modeling approaches using a variety of different kinds of models. We emphasize intuitive ideas rather than mathematical rigor. We illustrate how such models represent alternatives that 1) can have much higher interpretability, 2) are more likely to meet underlying assumptions, 3) provide better fitted models, and 4) are readily implemented in widely distributed software products.     

Statistical methods of quantal analysis in computerized compared with physiological experiments

Amplitude distributions of postsynaptic potentials subject to binomial distribution were simulated in computer-based experiments. Effects of sample size (N) and standard deviation of noise (S_n) on accuracy of determining mean quantal content (m) and quantal value (v) were investigated using four quantal analysis techniques (histograms, variation coefficient, failure and combined techniques). It was found that m and v may be determined fairly accurately (to within 10%) at S_n<2v using the last three techniques mentioned and at S_nv (where N=500–1000). It is possible to obtain similar results for N=50–200 if the experiment is repeated ten times. The possibility of applying such techniques to actual physiological results was confirmed by analyzing an extensive trace (N=1333) of inhibitory postsynaptic potentials in sensorimotor cortex units of unanesthetized rabbits.Brain Research Institute, National Mental Health Research Center, Academy of Medical Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 22, No. 2, pp. 206–215, March–April, 1990.     

Regulation of bacterial physiological processes by three types of protein phosphorylating systems

A single type of protein-phosphorylating system, the ATP-dependent protein kinases, is employed in the regulation of a variety of cellular physiological processes in eukaryotes. By contrast, recent work with bacteria has revealed that three types of protein-phosphorylating systems are involved in regulation: (1) the classical protein kinases, (2) the newly discovered sensor-kinase/response-regulator systems, and (3) the multifaceted phosphoenolpyruvate-dependent phosphotransferase system. Physiological and mechanistic aspects of these three evolutionarily distinct systems are discussed.     

Morphological and physiological characterization of fiber types in the iliofibular muscle of Rana esculenta]

In both longitudinal and cross sections of the M. iliofibularis of Rana esculenta three types of muscle fibres are identified by means of light and electron microscopy. These fibretypes called A-, B- and C-fibres are according to the fibres of m. rectus abdominis of the frog. They can be compared with the fibres of the m. rectus abdominis of rat and mouse. But there is another distribution of the fibretypes A, B and C in the m. iliofibularis and in the m. rectus abdominis. The m. iliofibularis is divided into two parts called "Tonusbündel" and "nichttonischer Teil" by means of their reaction to acetylcholine. The surface of the "Tonusbündel" consists of A-, B- and C-fibres while its inside is onlyformed by A- and B-fibres. They continue the "Tonusbündel" in the "nichttonischer Teil". This part chiefly consists of A-fibres. In cross sections their myofibrils are larger in their extent than the A-fibres known before. Therefore the A-fibretype has to be distinguished into two A-fibres: A1 and A2. The new one is called A2-fibre. A1-fibre is described in the "Tonusbündel" and in further investigations. The difference between the two fibres can be understood as a greater manifestation of power of the A1-fibre. The surface of the "nichttonischer Teil" of the m. iliofibularis consists of A2-fibres which easily could be found opposite the "Tonusbündel". At this point in contrary to the "Tonusbündel" could be found a defined morphological substrate for physiological investigations. The different reactions of "Tonusbündel" and "nichttonischer Teil" to acetylcholine could only be explained by the sum of reactions of all fibretypes in each bundle in correspondence with the reaction of the fibres in the neighbour bundle. But their different behaviour by summer- and winterfrogs is unknown. Therefore it is to discuss whether it is allowed to refer generally the results to "muscle" or "musclefibre" got from frogs living in cooled rooms. It is known in literature that not all results of physiological investigations can be interpreted with the two fibre- theorie ("twitch" and "slow") of muscle. Those not interpretable physiological results could be associated to the B-fibre can not be explained by morphological methods but must be proofed by physiological investigations. In tables are summerised morphological criteria of the three types and it is tried to associate the physiological qualities known from literature. Besides there is summerised the usual nomenclature with the first citations.     

Analysis of biochemical and physiological changes in wheat tissue culture using different germplasms and explant types

To select adequate wheat germplasms for genetic transformation, tissue culture efficiency of 21 different wheat lines (Einkorn, Emmer, Durum wheat, etc.) were compared, along with two different explants, namely, immature embryo and mature embryo. The results showed that the average differentiation rate and regeneration rate of immature embryo calli (46.5 and 20.82 %) were better than those for mature embryo calli (14.03 and 4.37 %). The best genotypes for immature embryo callus culture were ‘Ningchun 16’ and ‘Ei 15’, ‘Xiaoyan 22’, followed by ‘Durum 332’ and ‘Tr 256’. The best genotypes for mature embryo callus culture were ‘Ying 4286’, ‘Yunyin 01’, and ‘Xiaoyan 22’. To analyze how physiological and biochemical settings influence the totipotency of calli, different physiological and biochemical indices were analyzed. Differences between immature embryo callus and mature embryo callus were significant, as well as differences of most indices among different wheat types. The interaction effects between explant types and genotypes were also significant. Correlation analysis results showed that the total phenol and soluble sugar contents were significantly correlated with callus differentiation and regeneration rates.     

Euthanasia and the active-passive distinction

The author examines various claimed differences between active and passive euthanasia and, if there are differences, whether they are morally significant. He refutes arguments based on acting vs. not acting, intention, double effect, cause of death, and natural law theory. Reichenbach proposes that the most helpful distinction is the one between intentional killing (active euthanasia) and appropriate treatment for the dying or terminally ill (passive euthanasia). Significant moral difference, however, rests on the contention that intentional killing is always wrong and that, all else being equal, dying by natural means is intrinsically good, whereas dying by unnatural means is not.     

Fungicidal activity and chemical constitution

Six 4-(1-phenylalkyl)-, eight 4-(1-cyclohexylalkyl)-, seven 4-(1-cyclo-pentylalkyl)- and seven 4-(1-cyclobutylalkyl)-2,6-dinitrophenols, together with some derivatives, were tested against the powdery mildews of apple (caused by Podosphaera leucotricha) and blackcurrant (caused by Sphaerotheca mors-uvae) in the greenhouse and in field trials, against rose mildew (caused by S. pannosa) in the field, and against Venturia inaequalis in spore germination tests. Highest activity in the greenhouse was shown by members of the cyclobutyl series with 4–6 carbon atoms in the alkyl group. No phytotoxicity on healthy foliage occurred with any compound in these series.     

Thin filament diversity and physiological properties of fast and slow fiber types in astronaut leg muscles.

Slow type I fibers in soleus and fast white (IIa/IIx, IIx), fast red (IIa), and slow red (I) fibers in gastrocnemius were examined electron microscopically and physiologically from pre- and postflight biopsies of four astronauts from the 17-day, Life and Microgravity Sciences Spacelab Shuttle Transport System-78 mission. At 2.5-microm sarcomere length, thick filament density is approximately 1,012 filaments/microm(2) in all fiber types and unchanged by spaceflight. In preflight aldehyde-fixed biopsies, gastrocnemius fibers possess higher percentages (approximately 23%) of short thin filaments than soleus (9%). In type I fibers, spaceflight increases short, thin filament content from 9 to 24% in soleus and from 26 to 31% in gastrocnemius. Thick and thin filament spacing is wider at short sarcomere lengths. The Z-band lattice is also expanded, except for soleus type I fibers with presumably stiffer Z bands. Thin filament packing density correlates directly with specific tension for gastrocnemius fibers but not soleus. Thin filament density is inversely related to shortening velocity in all fibers. Thin filament structural variation contributes to the functional diversity of normal and spaceflight-unloaded muscles.