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Summary A review is given on advances in endosperm research in angiosperms. Endosperm is a very important nutritive tissue for the developing embryo. In sexually reproducing angiosperms endosperm develops as a consequence of double fertilization when one of male gametes is introduced to the central cell of megagametophyte. Of the three types of endosperm: nuclear, cellular and helobial, the nuclear...
Summary Large segments of the population are expo sed to environmental tobacco smoke (ETS), which is a risk factor for lung cancer and heart, circulatory and respiration diseases. Recently ETS was classified as an A carcinogen. Maternal smoking during pregnancy has been shown to be associated with pregnancy complications and deficits in the growth and development of the offspring. The effects of maternal...
Summary In sexually reproducing flowering plants both embryo and endosperm development is initated by fertilization (double fertilization) and in the vast majority of these plants a ratio of 2 maternally derived genomes to 1 paternally derived genom (2m:1p) is essential for endosperm formation and therefore for seed development. However, there is a group of taxa in which reproductive development is...
Summary Insect pests are a major cause of damage of the world's commercially important agricultural crops. Current strategies aimed at reducing crop losses rely primarily on pesticides. One of the commonly used organic zoocides is rotenone. It is used in gardens for both insect control and fish eradication as part of water management. Chronic exposure to rotenone can be toxic to animals and people...
Summary In nerve cells, the permeating short-lived signalling molecule of nitric oxide (NO) is generated by Ca2+ -calmodulin-stimulated NO synthase (NOS). Nitric oxide activates soluble guanylate cyclase (sGC) in target cells, leading to the formation of cyclic guanosine monophosphate (cGMP). Biochemical studies have shown the presence of Ca2+ -calmodulin-regulated NO-cGMP signalling mechanism in...
Summary The current postgenomic phase in biology is characterized by the occurrence of numerous novel research areas. Within the next twenty years or so, some of them will probably develop into well defined sub-disciplines, the other will disappear or transform into something completely new. Of the emerging directions, three seem particularly promising. They are: comparative genomics, deep analysis...
Summary The Brazilian gray short-tailed opossum (Monodelphis domestica) is a member of Didelphidae, the oldest extant family of marsupial mammals. In the wild they are solitary, omnivorous animals feeding also on insects and small vertebrates, captured as a result of active searching and hunting behavior. They are living in the semiarid tropical part of South America. This species was introduced as...
Summary In the last decade soil invertebrates are considered as "webmasters" in terrestrial ecosystems. It was found that interactions between soil faunal and microbial communities are extremely important for decomposition rate and nutrient cycling. The impact of soil invertebrates on soil structure is so significant, that they are reckoned as ecosystem engineers. Groups of invertebrates...
Summary Dyslexia, i.e. specific reading disability, is a phenomenon known from 100 years but its causes are still unrecognised. At the end of the last century cases of ,,word blindness" resulting from lesions to angular gyrus were diagnosed, which provoked persisted interpretation of reading disability in terms of congenital malfunctioning of that area of brain. Thus, belief that dyslexia is...
Summary Chromatin structure modulates the rate of DNA damage formation and repair in different regions of eukaryotic genomes. Chromatin rearrangement takes place during repair to increase accessibility of damage to repair proteins. Activity of histone acetyltransferases and chromatin remodeling complexes seems to be essential for nucleosome rearrangement during repair. Once repair is completed, reconstitution...
Summary The processes related to memory and motivation are necessary for the preservation of the animal's integrity. This review describes behavioral investigations concerning the role of some deprivations in early infancy on the development of memory and motivation in cats. The emphasis of this review is on the influence of (i) lab-rearing conditions and/or vi sual deprivation on the performance...
Summary The hydrobiological literature abounds in phenomena that are difficult to explain at the present state of knowledge. They have been named paradoxes; among them the most frequently discussed of which are the drift, plankton and Allen paradoxes. The first concerns the lack of noticeable losses in benthos density in upper stream sections despite continuous movement of invertebrates downstream...
Summary Distribution of zinc-lead resources in Olkusz region (southern Poland), the history of mining activities in this area (XIII-XX century), generation of mine spoils with high concentration of zinc, lead and other heavy metals, as well as the history of botanical studies on mine spoils in Olkusz region are described. The authors present detailed ecological studies on mine spoils of different...
Summary The present paper considers possible mites community indicators. They are based on the following characteristics: species abundance, dominance structure, life histories, trophy types, morphotypes and habitat preferences. In the early stages of succession, predominantly small fast developing pioneer nemathophagous species from open habitats were found. The proportion of species with parthenogenetic...
Summary Identification of a plant specimen is the key to the knowledge about it. Labeling a plant with its (scientific) name is crucial for gathering various facts pertaining to its ecology, distribution, practical uses, etc. When a human-based expertise is not available, the only way to determine the plant name is to use a diagnostic key. Until quite recently this kind of publications assumed a printed...
Summary Within the borders of the town man has created specific conditions for plant growth. Urban areas are very heteregeneous and contain a large number of habitats, which vary when passing from the city centre towards the outskirts. The over-heating of city centres referred to as "heat island" has been noted in many European towns. The analyses of the temperature maps and satellite infra-red...
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