Postepy Biologii Komorki, vol. 27, 2000, nr 1

Summary: The 1999 Nobel Prize in Physiology and medicine was
granted to Günter Blobel.

Summary: This paper discusses the xanthophyll cycle, its regulation and components and a connection with chlorophyll a fluorescence and describes the importance of the xanthophyll cycle as a photoprotection mechanism of photosynthesis. The influence of abiotic stress factors such as high and low temperature, temporary water and nutrient deficit and environmental pollution on xanthophyll cycle and chlorophyll fluorescence are also explored.

Summary: The aim of this review is to present a concrete model of apoptosis, namely the physiological death of mammary epithelial cells, and put emphasis on the role of Bcl-2 related proteins in the regulation of this process. The `paper is based on the literature and our own observations related to the regulatory mechanisms of mammary gland remodelling. Bax and Bcl-2 belong to the key regulators of apoptosis controlling ion (K+, H+, Cl-, Ca2+) and reactive oxygen species fluxes within the cell, releasing apoptogenic factors (AIF,cytochrome c) from mitochondria and activating executors of apoptosis (caspases, DNases). Apoptosis of mammary epithelial cells studied both in vitro (cell cultures i.e. HC11 and MCF-7) and in vivo (i.e. mammary gland of goat during lactation and involuting mammary gland of sow) is associated with the altered expression of bax and bcl-2 and intracellular redistribution of their products. In general, "survival factors" i.e. prolactin, EGF increase expression of bcl-2 and inhibit expression of bax, whereas "death factors" i.e. auto-/paracrine functioning TGF-b1 increase intracellular Bax/Bcl-2 ratio. TGF-b1 in addition to transcriptional activation stimulates redistribution of Bax protein from cytosol to organellar membranes (mitochondrial, endoplasmic reticulum, Golgi apparatus) and to nucleus. The end of lactation is associated with the drop of endocrine secretion of lactogenic hormones (prolactin, growth hormone), which in turn leads to augmented expression of local, intramammary derived growth inhibitors and inductors of apoptosis (TGF-bS, FIL, MDGI, mammastatin). Consequently, increased expression of apoptotic promoters (Bax, Bcl-xs) and activation of executors inevitably leads to massive apoptosis of epithelial cells, responsible for involution of mammary gland.

Summary: In this article the mode of infection with HIV-1 virus and the role of glycoprotein 120 (gp120) in this process were described. The gp120 is responsible for a number of phenomena resulting from HIV-1 infection. Against the epitopes of gp120 humoral and cellular responses develop. However, because of a high variability of this protein, caused by mutations, in the process of infection these responses become ineffective. Moreover, gp120, as revealed from numerous studies, causes a decrease in the number of peripheral blood CD4+ T lymphocytes, both infected and uninfected. This is caused by induction and participation in the processes such as: inhibition of CD4 receptor expression on the surface of infected lymphocyte, formation of syncytia, antibody-dependent cell-mediated cytotoxicity and apoptosis. Together with other factors, these processes result in developing of fully symptomatic acquired immunodeficiency syndrome (AIDS).

Application of protein product of the env gene, gp160, in the immunization against HIV-1 virus

Summary: The aim of this article is to present the attempts of immunization against HIV-1 with the use of protein products of the env gene. Newly elaborated techniques allowed replacing traditional vaccination methods, ineffective in case of highly variable HIV-1 virus and investigating alternative solutions such as: immunization with the use of recombinant viruses as vectors or "naked" DNA. The results of these studies are promising and indicate the way to solve this problem. However, because of high variability of HIV-1, haplotype variability in human population and still insufficient knowledge on host:pathogen interaction, it seems that effective, universal vaccine against HIV-1 will not, if ever, be constructed soon.

Summary: Homocysteine, a sulphur-containing non-structural protein aminoacid is a non-lipid factor in the pathogenesis of artheriosclerosis. The metabolism of homocysteine and the processes responsible for the high serum level of this aminoacid are described. The pathogenesis of artheriosclerosis depends directly or indirectly on high serum levels of homocysteine, which generate disorders in proteins, DNA and lipid methylation, changes the expresion of some genes and secretion of EDRF. Indirect effects of homocysteine mostly involve the generation of free radicals causing endothelium injury, proliferation of vacular smooth muscle cells and structural changes in the extracellular matrix. All these changes result in the generation of artheriosclerosis plates, hyperproliferation of vacular myocytes and changes in vasodilator and artheriotrombosis activities, which cause the progression of artheriosclerosis.

Summary: New developments in molecular genetics, explaining over the past decade the changes in floral organ identity and distribution, are presented and discussed. Specific mutations of homeotic genes changing flower phenotype are described as factors leading to the outstanding diversity of floral patterns present in Angiosperms. Special attention is paid to the systems interacting with each other as well as acting independently. Aspects of meristic variation are underlined as important for the development of different floral symmetry in evolutionary lines of Monocots and Eudicots.

Key words: flower morphogenesis, homeotic genes, meristic variation, symmetry, floral organ identity.

Agnieszka LACHOWICZ, Elżbieta RĘBAS, Ludmiła ŻYLIŃSKA, Lilla LACHOWICZ

Various aspects of protein kinases action in apoptosis

Summary: Apoptosis is a complex process requiring collaboration of several intracellular and extracellular factors. It is known that some intracellular agents controlling cell proliferation and differentiation could modulate apoptosis. Among others, the protein kinases could be involved in control of apoptosis, because it is well known that protein phosphorylation plays important role in this process. Although it is clear that protein kinases may take part in apoptosis but still their role is not obvious. So far there are the data showing that protein kinases could be engaged either in stimulation or inhibition of this process. However, experimental procedures and biological materials used in the studies concerning apoptosis are various, thus it is hard to clearly explain the role of protein kinases. It is too early for setting up any hipothesis, so our paper showing the latest data concerning this problem, shows also complicate way of action of protein kinases in programmed cell death.

Key words: protein kinases Ser/Thr, apoptosis

[Postepy Biologii Komorki 2000; 27: 111�122]

Maciej ŁAZARCZYK, Tomasz GRZELA

Family of trefoil peptides

Summary: The trefoil family of peptides is mainly associated with gastrointestinal tract. These peptides protect the mucous layer. The protective role of trefoil peptides is explained by their interaction with carbohydrates attached to mucin glycoproteins and by maintenance of the mucus structure. Trefoil peptides influence migration of epithelial cells and thus contribute to regeneration of the mucous layer. A correlation between trefoil peptides and oncogenesis remains unclear. In the gastrointestinal tract, trefoil peptides are considered to be one of more important factors protecting them against cancer. However, in lobular breast cancer, trefoil peptides may facilitate the tumor development. Possibly, a migration of neoplastic cells, influenced by trefoil peptides is responsible for metastases and tumor progression.

Key words: trefoil domain, mucous membrane, regeneration, gastrointestinal tract, cancer

[Postepy Biologii Komorki 2000; 27: 123�136]

Grzegorz JACKOWSKI

The structure and functional properties of photosystem I

Summary: The photosynthetic light reactions are effective due to cooperation of four functional complexes of thylakoid membrane. Within the framework of this cooperation PS I mediates light-driven electron transport from plastocyjanin to ferredoxin which then reduces NADP+ to NADPH. The second function of PS I is mediating cyclic elctron flow in cooperation with cytochrome b6/f complex. PS I domain directly engaged in electron transport along with a group of proteins performing structural role comprise a PS I core. The energy necessary for electron -transporting events is harvested and transferred to PS I core and its photochemical reaction center by the set of inner and peripheral antennae. It is the matter of last few years that the fundamental progress regarding structural organization of PS I core has been achieved (some details of Synechocystis sp. PS I core structure were imaged at a resolution better than 0.14 nm); considerable progress has been reached concerning LHC I structure and functions as well. The goal of the review is to present a current awarness in the area of PS I holocomplex structural organization including functional aspects.

Key words: PS I, LHC I, LHC II, grana lamellae, stroma lamellae, core, Psa A/Psa B heterodimer

[Postepy Biologii Komorki 2000; 27: 137�150]