Partitioning of current photosynthates towards primary metabolites and its simultaneous incorporation in leaf alkaloids was investigated in developing leaves of medicinally important Catharanthus roseus. Of the total 14CO2 assimilated, the leaves at positions 1-6 fixed 8, 22, 25, 19, 13, and 8 %, respectively, and stem 3 %. Leaf fresh mass, chlorophyll content, and CO2 exchange rate increased up to the third leaf. The total alkaloid content was highest in young actively growing leaves, which declined with age. Total 14C fixed and its content in ethanol soluble fraction increased up to the third leaf and then declined. The 14C content in primary metabolites such as sugars and organic acids was also highest in the 3rd leaf. The utilization of 14C assimilates into alkaloids was maximum in youngest leaf which declined with leaf age. Hence the capacity to synthesize alkaloids was highest in young growing leaves and metabolites from photosynthetic pathway were most efficiently utilized and incorporated into alkaloid biosynthetic pathway by young growing leaves. and N. K. Srivastava ... [et al.].
Vnitrodruhová variabilita v chování zvířat, tj. personalita, výrazně ovlivňuje ekologické i evoluční procesy. V tomto článku se pojednává o tom, jak může personalita vzniknout u pavouků a její vliv na potravní sítě., Inter-individual behavioural differences, i.e. personalities, play a very important role in eco-evolutionary processes. Here, we describe how spiders’ personalities arise and how they influence the dynamics of food webs., and Radek Michalko.
Based on data from three group interviews conducted with groups of “workers” and “professionals”, this article focuses on ways that interviews participants choose in their attempts to cope with sociologists’ demands to describe social structure of the contemporary Czech society. The key category adopted from the interviewers’ questions around which the arguments of participants were centered is the category of “success“. The author analyses measures of success mentioned by participants, its presuppositions, who is regarded as successful by them and which criteria of success they adopt. Also analyzed is the self-positioning of the interview participants and the social group they identify with in the notions of social structure presented by them in the course of the interviews., Ivan Vodochodský., and Obsahuje seznam literatury
The aim of the study is to evaluate the circumstances revealed by the archaeological study of extinct medieval villages whose ground plans were staked out systematically, using some of the standard schemes of the times: that is, the possible direct proportion of the area, farmed by the individual homesteads, and the expanse of the plot of yards of these homesteads, or rather the width of the yards with respect to the village square. For the initial phase of the analysis were used the available early textual and cartographical sources from areas where such research was made possible by the earlier interconnecting of information about the history of settlement that allow for studying the older stages of social structure of the communities.
In the temperate haptophyceaen Pavlova luíheri (Droop) Green and Pavlova sp. (not yet estimated) the dominant pigments were chlorophyll (Chl) a (57 %), fucoxanthin (17 %) and diadinoxanthin (13 %); other estimated pigments were p-carotene, Chl c, cA-fucoxanthin and diatoxanthin. UV-A of 1.7 W m-2 had no effect on pigmentation of P. luíheri, but led to a reduction of the pigment contents of Pavlova sp. The damaging effect of a high UV-A dose (11.0 W m'^) was more pronounced than that of UV-B irradiance. The strongest reduction of pigment concentrations of both Pavlova species was observed after an exposure to UV-A (11.0 W m'^) plus UV-B (1.2 W m-2). Under this combined irradiation an increase of the diatoxanthin content and a decrease of the diadinoxanthin content was found.
In this minireview, the factors involved in the development of corneal injury due to an increased amount of UVB rays are summarized. Experimental studies have shown that an increased number of UVB rays leads to a profound decrease in corneal antioxidants (high molecular weight, antioxidant enzymes as well as low molecular weight, mainly ascorbic acid) so that a prooxidant/antioxidant imbalance appears. The decrease of corneal antioxidant protective mechanisms results in oxidative injury of the cornea and causes damage of the inner parts of the eye by UVB rays and by reactive oxygen species generated by them.
In clusterbean leaves UV-B radiation caused a reduction in contents of chlorophylls and carotenoids and in the efficiency of photosystem 2 photochemistry. The degree of damage was reduced when UV-A accompanied the UV-B radiation. This indicates the counteracting effect of UV-A radiation against UV-B-induced impairment. and S. Gartia ... [et al.].