A comparison has been made between the chaetotaxy of the gyrodactylid monogeneans Macrogyrodactylus clarii Gussev, 1961 and M. congolensis (Prudhoe, 1957) Yamaguti, 1963 from the gills and skin, respectively, of the catfish Clarias gariepinus (Burchell) from the river Nile in Egypt. Bilaterally arranged argentophilic structures on the surface of these parasites are presumed to be sensilla and are more abundant in M. clarii than in M. congolensis especially on the ventral surface (124 vs. 66). In both species these sensilla are concentrated on the head lobes and in the pharyngeal region, but there are features of the sensilla patterns that can be used to distinguish the two species. Comparison is made with sensilla patterns of other gyrodactylids. A system of cells and dendritic processes, most probably part of the nervous system, also has an affinity for silver in the two species. There are no previous records of extensive argentophilic elements in the nervous systems of monogeneans.
The article deals with the ability non-respirable dust fraction suppression for the optical dust monitor based-on the light scattering by the dust particles. As far this function for this type dust monitor is performed by mechanical means, e.g. a cyclone. The article tries to realise this function by using signal processing acquired from the light scattering by the dust particles. and Obsahuje seznam literatury
Pea (Písum sativum L.) leaves fully developed under either high or low irradiance were exposed for up to 30 h to dark oř limiting, saturating oř excessive iřřadiance. The time courses of degradation of a popidation of radioactively prelabelled Dl protein and the fluorescence parameter Fv/Fm, measured on intact leatf discs at room temperature were studied. The Dl protein degradation was shown to be dependent on irradiance but not directly correlated with changes in photosynthetic capacity. The irradiance dependence of Dl protein degradation was different in the two types of leaves and it occurred at a slow but significant rate in the daik. The irradiance dependence of Dl degradation tnay be associated with the 3-dimensional structure of the thylakoid membrane and is suggested to play a key role in flie regulation of radiant energy absorption and photosynthetic capacity of flie leaves.
Low temperature (LT) is one of the major factors that limit crop production and reduce yield. To better understand the cold-tolerance mechanism in the plantains, a sensitive cultivar Williams (Musa acuminata AAA cv. Williams) and a tolerant cultivar Cachaco (Musa paradisiaca ABB cv. Dajiao) were used. LT resulted in increased malondialdehyde (MDA) content, elevated contents of hydrogen peroxide (H2O2) and superoxide radical (O2.-), and decreased photochemical efficiency (Fv/Fm) and net photosynthetic rate (PN), but cv. Cachaco showed better LT tolerance than cv. Williams. After LT treatment for 120 h, total scavenging capability (DPPH. scavenging capability) in Williams showed a significant decrease but no significant alternations was found in Cachaco. Ascorbate peroxidase (APX) and peroxidase (POD) displayed a significant increase but superoxide dismutase (SOD) showed no significant alternations and catalase (CAT) showed a significant decrease in Cachaco after 120 h of LT treatment. All the four antioxidant enzymes above showed a significant decrease in Williams after 120 h of LT treatment. Our results suggest that higher activities of APX, POD, SOD, and DPPH. scavenging capability to a certain extent can be used to explain the higher cold tolerance in the plantain, which would provide a theoretical guidance for bananas production and screening cold-resistant variety. and Q. Zhang ... [et al.].