The role of microtubules in the secretory processes in the tegument of adult trematode Fasciola hepatica L. is studied by estimating the effects of colchicine, a substance known to disrupt microtubules, on the number of T2 vesicles. Tissue slices of Ihe worm are incubated in Hedon-Fleig medium with or without 5 x 10'4M colchicine. The dynamics of the colchicine-provoked secretory block is examined by morphometry on samples processed for electron microscopy. T2 vesicles are estimated as a total number or separately within three levels (apical, sub-apical and central) of the distal tegument. The secretory block is demonstrated as reduction in the total number of T2 vesicles. The separate counting within three levels of the distal tegument demonstrates in control samples a trend of sub-apical condensation of T2 vesicles. This pattern of T2 distribution remains unchanged in colchicine-treated samples in spite of the reduction of the mean T2 counts within each of the levels examined. The data illustrate the role of microtubules in both the tegumental transport of secretory vesicles and the stratification of the organelles within the tegument.
Theronts of the ciliate Ichthyophthirius multifiliis (Fouquet) with up to 4 micronuclei were recorded in populations from two different parasite isolates, maintained as primary infections in juvenile carp through 2 and 10 cycles, respectively. The largest number of multimicronucleate forms occurred within the older isolate (10 cycles) following cyst incubation at 20"C. Tro-phonts were induced to emerge from the host epidermis following incubation of the fish in Eagles MEM for 10-15 min at 20"C. This provided for the first time a technique to recover trophonts in all stages of development; observations were made on the transition from theront to trophont, with respect to nuclear events, the organelle of Lieberklihn, and phagocytosis of host cells. On re-exposure of carp already carrying a two-day primary infection, recently entered trophonts were found in various stages of fusion with established parasites. Results are discussed with respect to conjugation, anisogamy and senescence.
Terbium (Tb^'*") was ušed as a fluorescence probe in the study of calcium-binding sites on 33 kDa protein of photosystem 2. The fluorescence of Tb^^ was enhanced markedly when bound to the 33 kDa protein, and the non-radiative energy transfer between tryptophan (Trp) residue and Tb^+, bound to the calcium-binding sites on the 33 kDa protein, took plače. According to the Forster non-radiative energy transfer mechanism, the average distance between the bound Tb3+ and Trp residue was found to be 1.05 nm. The pH titration indicated that major groups in the 33 kDa protein, involved in Ca2+ ions binding, were the carboxylic side groups of the glutamic acid and/or aspartic acid.
A number of art historians have noted how in around 1800 the social function of the visual arts in the Czech Lands fundamentally changed and a new ideal of bourgeois vizuality emerged. At the same time, visual culture in the Age of Enlightenment came to be seen as a ‘movement of knowledge’ through different cultural spheres. Reacting to the discussion of Daniela Tinková’s view of the Enlightenment as a process of spreading and democratizing knowledge and extending information networks, the present text develops these ideas and considers other ways in which art in the Czech Lands during the Enlightenment could be conceptualized. We point out that new centres of culture and broad-based social penetration brought not only changes in the way information on the visual arts was disseminated, but a new situation in which the exchange of knowledge across a variety of social and educational fields was no longer restricted to the hitherto clearly defined professions that had established the prevailing terminology and methodology in their own domains. For example, professional artists might now explore all sorts of fields of knowledge, while traditional humanistic art-theoretical discourse began to attract not only dilettante ‘amateurs’ but also a new class of professional art experts and critics with no formal artistic training. and The study of art thus became an independent branch of knowledge, a component of education, a source of cultural and historical memory, and a badge of patriotism and personal identity. A similar shift can be observed in modes of visual perception, which in the Enlightenment were moulded by an endeavour to extend the traditional range of art consumers and recipients by means of aesthetically oriented education and training. There was also a clear attempt to fulfil the ideal of public art based on modern criteria of ‘taste’, aimed at eliminating persisting social barriers and the cultural monopoly of established aristocratic elites and creating a template for a bourgeois visual culture (sensibility, reappraisal of hierarchy of genres, instruction in drawing, growth of graphic art, etc.). This movement of knowledge also made it far easier for recipients to find their bearings in the art market (exhibitions, reviews, advertisements) by providing them with criteria for judging the quality of artworks and, more generally, promoting the visuality of the dawning industrial age (public access to art collections, industrial exhibitions, the first museums, etc.), and hence to a hitherto unseen extent opening up the world of visual art to the wider public.
Four dones of Miscanthus spp., collected from regions with different rainfall distribution, were transplanted in pots and subjected to five drying cycles (each of 6- 7 d). Gas exchanges were measured on attached leaves, The light-saturated photosynthetic CO2 uptake (P^) began to dechne when the leaf water potential (y\) was reduced to -1.3 - -1.5 MPa, and the values corresponding to 50 % decrease P^)] were -1.6 - -2.6 MPa. The P^ ) values were lower in a cloně collected from Kilung (northem Taiwan, highly frequent rainfall) than in dones collected from Kenting (southem Taiwan, distinct wet and dry season). Besides, the ^(1/2 Pj^) value became lower in all the tested dones when the drying cycle advanced (in the drying cycle of northem Taiwan cloně and in the 5‘*’ drying cycle of southem Taiwan dones, řespectively). Both the stomatal and non- stomatal factors of photosynthesis were affected by water deficit, and the osmotic adjustment mitigated the negative impact of water deficit on both factors. The clonal differences in the tolerance and acdimation of photosynthesis to water deficit are dosely related to the osmotic adjustment, and the clonal differences in osmotic adjustment reflect the rainfall pattem of sampled region.
An examination of a sample of European eels, Anguilla anguilla (L.), collected from Lake Bracciano near Rome in 1993, the only known European locality with the occurrence of the introduced swimbladder nematode Anguillicola novaezelandiae Moravec et Taraschewski, 1988, revealed for the first time the presence of two Anguillicola species, A. novaezelandiae and A. crassus. In view of the investigations carried out by current authors in Bracciano Lake in the years 1982-1992, it is apparent that the latter species has been introduced into the lake quite recently, where it quickly became a dominant species. The development of A. novaezelandiae was experimentally studied in the copepod intermediate host, Cyclops strenuus, for the first time. The copepods were infected with nematode second-stage larvae at 21-22°C; fully developed infective third-stage larvae were obtained 13 days p.i. The general morphology of individual larval stages of A. novaezelandiae was similar to that of larvae of the related species Λ. crassus.
Schistosoma monsoni (Puerto Rican strain) cercariae were exposed to 10, 20, 50, 100, 200, 300, 400 and 500 krad gamma radiation from “Co gamma source. From 10-100 krad irradiation no differences could be found in the behaviour of the cercariae when compared to the controls. From 200-500 krad there was an increase in mortality as well as in the number of cercariae that shed their tails. The Con A binding studies also performed on cercariae radiated with up to 100 krad indicate a direct relationship between the number of cercariae that bind Con A and radiation dose. All live cercarial heads collected after radiation also bound Con A. It thus seems possible that irradiation may act as a stimulus for cercariae to transform to schistosomulae.
The missal of Načeradec is a modest codex from an artistic point of view. Its decoration is limited to one figural illumination only – a canon depiction of the Crucifixion; besides this, the manuscript contains only filigree initials and clerical capitals. The quality of its figural decoration is comparatively high. Its style is post-classical Gothic; linear pleats of the draperies imply a date in the beginning of the 14th century. Only a few analogies can be found in simultaneous book painting, e.g. in the decoration of the manuscripts of Eliška (Elisabeth) Rejčka, but these analogies are not immediate. Some correspondence, however, can be found in monumental art, more precisely in mural painting.