Genetic Evidence Concerning the Structure of the Tetrahymena thermophila Macronucleus*†

Synopsis.
A satisfactory model of the Tetrahymena thermophila macronucleus must explain its genetic behavior in terms of its constituent molecules. Particular genetic phenomena requiring explanation are (a) phenotypic assortment , here interpreted as resulting from allelic disjunction rather than from differential gene expression; (b) unequal allelic input for some loci , interpreted as a consequence of unequal and selective replication of some alleles during early macronuclear development; (c) delayed assortment at some loci , interpreted as an effect of inequality of allelic input combined with a generalized elevation of DNA content during early clonal history; (d) linkage disruption , probably reflecting continuous somatic recombination rather than dissolution of chromosomes into small repliconic units; (e) assortment depression , brought about by the occasional association of homologous replicons (chromosomes) or else by a differential increase in some classes of replicons; (f) ploidy-related developmental differences in macronuclear primordia are interpreted on the basis of quantitative differences in DNA rather than in terms of an early perception of genic imbalance, (g) Ploidy independent macronuclear DNA content is consistent with several models of size regulation.     

Sexual shape dimorphism in the skull of the hooded seal Cystophora cristata

Multiple-group principal component analysis was used to investigate morphological differences between skulls of male and female hooded seals. The scores on the first principal axis (PCI), calculated from the variance-covariance matrix of log-transformed data, were highly correlated with age and the component was interpreted as a general growth axis. The other components had correlations between dimensions and component scores of different signs and magnitude and were interpreted as shape axes. The standardized component scores were subjected to analyses of variance and discriminant analyses. Sexual dimorphism was disclosed on eight of the components including PCI, and was functionally related mostly to the hood of the males.     

Tachykinin in the Regulation of Choleresis

Based on experiments on dogs and rats, receptor mechanisms of the influence of substance P (tachykinin) and its agonists on the level of bile secretion and composition are interpreted.     

Study of the characteristics of the effect of radio-sound using spherical models

Experimental data are presented on sound wave excitement in liquid sphere models by pulse HF-fields and interpreted in relation to microwave auditory effects.     

A reinterpretation of the mathematical biophysics of the central nervous system in the light of neurophysiological findings

The fundamental equations for the interaction between neurons used in mathematical biophysics seem at first incompatible with the actual neurophysiological findings on the synaptic transmission. It is shown, however, that those equations may be readily interpreted in terms of accepted neurophysiological views. What has been termed “synapse” in mathematical biophysics must be regarded as a complicated network of internuncial neurons. It is shown that, under rather conditions, the number of those interneurons willstatistically vary with time according to the differential equation postulated for the excitatory and inhibitory factors. The latter are thus interpreted as the number of excitatory and inhibitory interneurons.     

Asteroid and Ophiuroid Trace Fossils from the Lower Cretaceous of Chile

Abundant asterozoan trace fossils in the Lower Cretaceous Apeleg Formation of southern Chile were produced by the infilling of traces made by asteroids and ophiuroids on a muddy surface. Most are preserved as hypichnial ridges formed as casts on the bottom of fine-grained sandstone laminae. Star-shaped Asteriacites lumbricalis are interpreted as the infillings of shallow excavations made by asteroids. Hook-shaped and sinuous ridges of the newly defined ichnogenus and ichnospecies Ophioichnus aysenensis are interpreted as the casts of imprints made by the walking action of the arms of ophiuroids. Deposition probably took place in an offshore tide-swept marine shelf environment. In life the animals formed an assemblage equivalent to echinoderm aggregations on the modern sea floor.     

Secretory carcinoma of the endometrium

A case of secretory carcinoma of the endometrium in a 21-year-old woman is reported. Endometrial smears were interpreted as showing a differentiated adenocarcinoma. Smears of ascitic fluid obtained during subsequent surgery showed similar findings; periodic acid-Schiff staining of the smears revealed abundant positive material in the cytoplasm. These findings were interpreted as evidence of secretory carcinoma, which was confirmed by histopathologic study of the biopsy and surgical specimens.     

Principal-Component Analysis of the Characteristics Desirable in Baker's Yeasts

Twenty-seven properties considered to be required for good bakery products were examined in 56 industrial and 2 laboratory yeast strains. The data obtained were applied to principal-component analysis, one of the multivariate statistical analyses. The first and second principal components together were extracted, and these accounted for 77.7% of the variance. The first principal component was interpreted as the glycolytic activity of yeast in dough, and the second one was interpreted as the balance of leavening abilities in sweet and flour doughs from the factor loadings. The scattergram on the two principal components was effective in grouping the 58 yeast strains used.     

Principal-Component Analysis of the Characteristics Desirable in Baker's Yeasts

Twenty-seven properties considered to be required for good bakery products were examined in 56 industrial and 2 laboratory yeast strains. The data obtained were applied to principal-component analysis, one of the multivariate statistical analyses. The first and second principal components together were extracted, and these accounted for 77.7% of the variance. The first principal component was interpreted as the glycolytic activity of yeast in dough, and the second one was interpreted as the balance of leavening abilities in sweet and flour doughs from the factor loadings. The scattergram on the two principal components was effective in grouping the 58 yeast strains used.     

Proton NMR study of methemoglobin and its isolated chains. Effect of the subunit association on the structure of the subunits.

In order to investigate the effect of the alpha beta subunit contacts on the subunit structure of human adult methemoglobin, the hyperfine shifted proton NMR spectra of several high spin complexes (water, cyanate, thiocyanate, formate, fluoride, and nitrite) and low spin complexes (imisazole, azide, and cyanide) of hemoglobin and its isolated subunits were characterized at 220 MHz and 22 degrees C. The spectra of ferric low spin derivatives of the isolated subunits were approximately superimposable on the corresponding hemoglobin spectra. On the other hand, the high spin spectra of the isolated subunits were greatly different from each other. The spectral anomaly in the ferric high spin complexes of the isolated beta subunit were interpreted to indicate other structural change than the hemichrome formation in the beta heme pocket. Difference in the subunit association effect between the high and low spin complexes of the isolated beta subunit was interpreted on the basis of a conformational change of the apoprotein dependent on the spin state of the beta heme iron.     

A Weichselia-Stiehleria-Matoniaceae community within the Quedlinburg Estuary of Lower Cretaceous age

The Hauterivian community of Nathorstiana and Hausmannia and the Barremian community of Weichselia, Stiehleria, Matonidium and Phlebopteris are interpreted as river-shore communities under maritime influence. A reconstruction of Weichselia reticulata is presented, in which the pronounced dimorphism of the fronds raises problems which cannot be interpreted in terms of normal Recent xeromorphic ferns.     

Rare Mollusca from the Lower Devonian Hunsrück Slate of southern Germany

Only ten gastropods have been recovered and a single hyolith found in the radiographic study of the Hunsrück fauna. Four gastropods are interpreted as retaining soft parts: the radula may be identified in one and perhaps the liver and digestive organs in the others. These gastropods may have moved into the area on floating vegetation. The hyolith probably lived on the bottom. Soft parts are present within its shell, but they are not readily interpreted. A tentacular mass anterior to a possible mantle cavity is present, with the bulk of the shell being filled by enigmatic tissue. ▭ Gastropoda, Hyolitha, soft parts, radula, pyritization.     

A Rare, Larval-founded Colony of the Bryozoan Archimedes from the Carboniferous of Alabama

Very few basal attachments of the spiralled fenestrate bryozoan Archimedes are known. A newly discovered specimen is interpreted to have grown on a thin cylindrical ephemeral substratum that extended above the sediment-water interface, allowing paired spirals to develop and to extend in opposite directions when the colony was very small.     

An analysis of the blood group composition of a population in Brittany, the Bigoudens

Data are presented on the blood groups of the Bigoudens. Deviations from the expected Hardy-Weinberg distribution are interpreted as the result of a recent mixing of previously separated groups, in addition to the effect of silent alleles and inbreeding. Special reference to the historical evidence of their origin is made.     

Late-glacial fluctuations of timberline in the Black Forest (SW Germany)

Based on pollen diagrams from nine sites at altitudes between 654 and 1280 m a.s.l. the Late-glacial fluctuations of the timberline are reconstructed and interpreted in terms of summer temperature.     

Influence of the reinforcement magnitude on omission effects

Reinforcement Omission Effects (ROEs), indicated by higher rate of responses after nonreinforced trials in a partial reinforcement schedule, have been interpreted as behavioral transient facilitation after nonreinforcement induced by primary frustration, and/or behavioral transient inhibition after reinforcement induced by demotivation or temporal control. The size of the ROEs should depend directly on the reinforcement magnitude. The present experiment aimed to clarify the relationship between reinforcement magnitude and the omission effects manipulating the magnitude linked to discriminative stimuli in a partial reinforcement FI schedule. The results showed that response rates were higher after omission than after reinforcement delivery. Besides, response rates were highest immediately after the reinforcement omission of a larger magnitude than of a smaller magnitude. These data are interpreted in terms of ROEs multiple process behavioral facilitation after nonreinforcement, and behavioral transient inhibition after reinforcement.     

Pressure effects on the photocycle of purple membrane

We studied the effects of hydrostatic pressure on the kinetics of the photocycle of purple membrane from Halobacterium halobium. The data were interpreted in terms of a unidirectional and unbranched model. We found that all of the distinct processes of the photocycle are retarded by pressure, with the earlier, fast processes showing less sensitivity to pressure than the later, slow processes. The qualitative similarity of these results with the effects of solvent viscosity on the photocycle kinetics suggests that the primary effects of pressure on the kinetics are via the intrinsic viscosity of the membrane and not via activation volumes. There is a strong quantitative correlation between the pressure effects and the solvent viscosity effects, further supporting this interpretation. We observed a monotonic decrease in the positive absorbance change signal at 640 nm near the end of the photocycle as the pressure is increased. This signal is usually ascribed to the O intermediate, and we interpreted our finding, along with evidence from other experiments, to mean that an ionizable group or groups, such as carboxylic acids, are undissociated and uncharged in O.     

Postovulatory aging of human ova: II. Spontaneous division of the first polar body

Two oocytes recovered from the Fallopian tube at 24 and 50 h following the LH peak in plasma were examined by light microscopy and transmission electron microscopy. The possibility of fertilization was excluded by clinical and morphologic evidence. In the earliest specimen, the first polar body showed condensed nuclear chromatin, without nuclear envelope, and is interpreted as entering interphase. In the other specimen, the first polar body was undergoing division, which is interpreted as spontaneous second meiotic division.     

Higher order structural organization of the nucleoid in the thiobacterium Thiosphaera pantotropha

Abstract Thiosphaera pantotropha cells treated with mitomycin C produced bacteriophages and showed cell lysis. Upon occurrence of cell lysis, samples were mounted for electron microscopy by negative staining. During mounting, the cell contents were spread at the surface of the support film. Besides polysomes, strands interpreted as DNA could be seen, most of them complexed with particles interpreted as DNA-binding proteins. Single and twisted strands were revealed, and complex structures with diameters around 35 nm were common. They exhibited an ordered arrangement of the proteins. Our findings suggest that bacterial chromosomal DNA complexed with DNA-binding proteins may be organized in higher order, similar to the compactation of nucleosome strands in eukaryotic chromosomal DNA.