The effect of ultraviolet B radiation (UV-B) on cellular ultrastructure, chlorophyll (Chl), carotenoids, and total phenolics of Acrostichum danaeifolium gametophytes was analyzed. The control group of spores was germinated under standard conditions, while the test group of spores was germinated with additional UV-B for 30 min every day for 34 d. The cell characteristics were preserved in gametophytes irradiated with UV-B, but the number of starch grains increased in the chloroplasts and the more developed grana organization in contrast to the chloroplasts of the control group. Chl a content decreased, while Chl b content increased in the gametophytes cultivated with UV-B for 34 d. Contents of lutein and zeaxanthin decreased and trans-β-carotene concentration was enhanced in the gametophytes irradiated with UV-B. The content of total phenolic compounds increased in the gametophytes cultivated with UV-B. Therefore our data suggest that the gametophytes of A. danaeifolium, a fern endemic to the mangrove biome, were sensitive to enhancement of UV-B radiation at the beginning of their development and they exhibited alterations in their ultrastructure, pigment contents, and protective mechanisms of the photosynthetic apparatus, when exposed to this radiation., A. M. Randi, M. C. A. Freitas, A. C. Rodrigues, M. Maraschin, M. A. Torres., and Obsahuje bibliografii
The paper deals with theoretical analysis of the catodioptric optical systems for astronomical telescopes and photographic telephoto lens. The formulas for calculation of parameters for four types of catodioptric optical systems are derived. The achromatic meniscus and two lens afocal optical system are used as a compensators of the residual aberrations of mirror systems. and Článek ze zabývá teoretickou analýzou katadioptrických (zrcadlo-čočkových) optických soustav objektivů používaných především v astronomických dalekohledech nebo jako teleobjektivy ve fotografii. Jsou zde odvozeny vztahy pro výpočet parametrů čtyř druhů katadioptrických soustav používajících jako kompenzátor achromatický meniskus nebo dvoučlenný afokální optický systém.
The morphology of the nematode Klossinemella iheringi (Travassos, Artigas et Pereira, 1928), the type species of the genus Klossinemella Costa, 1961, was studied using specimens collected from the serrasalmid fish, Mylesinus paraschomhurgkii légu, Santos et Ferreira, 1989 (a new host record), from the Trombetas River, Para State, Brazil, by both light and scanning electron microscopy. This species was also recorded from the Jari River (Pará State), the Uatuma, Pitinga and Capucapu Rivers (Amazonas State), and the Araguari River (Amapá State). An examination by SEM made it possible, for the first time in this genus, to study in detail the structure of the cephalic end. Characteristic features are the presence of 8 cephalic papillae arranged in two circlets, well developed lateral amphids, and especially a crown of 8 cephalic, Y-shaped sclerotized pieces (outgrowths). The male possesses 8 pairs of caudal papillae (3 preanals, 1 adanal and 4 postanals), two unequal spicules (0.156-0.294 mm and 0.069-0.099 mm long) and a gubemaculum (0.027-0.045 mm in length); previously undescribed deirids were also found. This is the first record of this parasite from the Amazon River basin. The genus Proatractis G. Caballero, 1971 is considered a synonym of Klossinemella Costa, 1961, belonging to the cosmocercoid family Atractidae, and its type species is transferred to the latter genus as Klossinemella parvicapilico-rnnala (G. Caballero, 1971) comb. n.