Flow Cytometric Analysis of Telomere Length and Telomerase Activity

Summary: The regulation of telomere length is involved in the cellular physiology of senes-cence and mechanism of cell immortalization and tumor formation mainly due to reactivation of telomerase. Telomerase is a telomere specific polymerase which hTERT protein compo-nent is catalytic subunit indispensable to its activity. The function of telomere-telomerase system has been demonstrated in most malignant tumors, germ lines and human lymphocytes during differentiation and activation. The measurement of telomere length has traditionally been performed by Southern blot whereas telomerase activity detection by PCR. Recently, flow cytometry based protocols evaluating telomere length and hTERT expression, providing information at single cell level, have been published. These methods offer simple and rapid assay particularly for large-scale study of clinical samples.

Key words:  telomere, telomerase activity, hTERT, flow cytometry

Sperm Autoantigens: I. Immunobiological Characterisation

Summary: Sperm antigens may provoke iso- and autoimmune responses. Therefore, it is important to identify and to purify isolated sperm entities specifically reacting with antisperm antibodies. This would allow to set an insight into immunological background of infertility and to prospectively develop procedures to vaccinate animal species and human beings for fertility regulation. The present review compiles data concerning the characterisation of the presently recognised sperm antigens that are distributed on the surface of the spermatozoon and within its internal compartments. Results of some animal studies towards identification of immunogenicity of particular sperm antigens are also updated.

Key words:  sperm, autoantigens, immunogens, antisperm immune responses.

Sperm autoantigens: II. Application and functional aspects

Summary: Sugar moieties represent the main component of external cell surface in Eucaryota. Their presence not only determines the physicochemical, immunological and biological properties of the plasma membrane. Sugar moieties do play a major role in cell interactions between. During fertilisation, male and female gamete receptors and their ligands undergo reciprocal interactions, determining the species-specific recognition and they control the subsequent fertilisation stages. Main aspects of the development of a contraceptive vaccine, based on components of the male gamete are also outlined.

Key words:  glycoproteins, sperm, fertilisation, immunocontraception

Genetic Regulation of Plant Embryogenesis

Summary: Over the past several years, substantial progress has been made toward the identification of genes involved in the embryo development. The majority of available information is coming from the analyses of embryo mutants of model plant – Arabidopsis thaliana. The special interest is given to the mutations in early stages of embryogenesis including those where the development is arrested in a specific stage. Analysis of such mutants enables recognition and understanding mechanisms of genetic regulation of embryogenesis. Many genes which are involved in the plant embryo formation had been cloned and precisely characterized.

Key words: embryogenesis, embryo mutants, Arabidopsis thaliana

Satellite Cells of the Skeletal Muscle

Summary: Satellite cells are potentially mitotically active population of mononucleate myoblasts, located in the vicinity of skeletal muscle fibers. The descendants of satellite cells, called myoblasts, after multiple rounds of divisions undergo fusions with existing muscle fibers resulting in their growth or regeneration. In cases of extreme muscle injury, this population is supported by other nonmuscle cells, like bone marrow cells, recruited to myogenic fate. On the other hand, primitive nature of satellite cells allows them to be commited to differentiation into hematopoietic precursors, due to environmental cues. Genetically modified myoblasts are good candidates for cell-mediated gene transfer. Myoblasts injected into muscle fuse to existing fibers resulting in local expression of the transgene. This way genetically modified growth factors could improve meat animal production. Attempts to use genetically modified myoblasts in treatment of muscle dystrophies has been also made. However, the procedures meet many obstacles like problems with isolation of pure population of muscle satellite cells, limited survival of modified cells after in vitro culture, low rate of successful transfections. Precise studies to understand biological nature of satellite cells will help in future to solve these problems.

Key words: skeletal muscle, satellite cells, muscle regeneration, muscular dystrophy.
 

Ethanol and Acetaldehyde: Participation in Mutagenesis and Carcinogenesis

Summary: Chronic alcohol abuse results in a variety of pathological effects, including damage to the liver and brain, as well as other organs, and is associated with an increased risk of certain types of cancers. The metabolism of ethanol leads to the generation of acetaldehyde and acetic acid. Acetaldehyde causes DNA and protein adducts and decreases DNA repair mechanisms, and traps glutathione, an important peptide in detoxification. During metabolism of ethanol by cytochromes, and alcohol dehydrogenase and xanthine oxidase free radicals can be also generated. Other mechanisms by which alcohol stimulates carcinogenesis include the induction of cytochrome P-450 2E1, associated with an enhanced activation of various procarcinogens, and nutritional deficiencies such as vitamin A, folate, zinc and selenium deficiency. In addition, local mechanisms in the upper gastrointestinal tract and in the rectum may be of particular importance. Such mechanisms lead to tissue injury such as cirrhosis of the liver, a major prerequisite for hepatocellular carcinoma.

Key words:  ethanol, acetaldehyde, comutagens, cytochromes, xenobiotics, alcohol dehydrogenase, xanthine oxidase, free radicals, adducts, DNA repair

Fractal Dimension in Morphology of Neoplasmas

Summary: In this work we presented selected aspects of existing results of investigations on possibility of use of new, developed in last years, branch of science – fractal-geometry, in investigation of neoplasms. Many definitions of fractal came into being. Discoverer of fractal geometry – Mandelbrot with this term characterized geometrical figures occurring out in nature (different from figures of Euclidean geometry). Two kinds fractal are distinguished – nonstochastic (not existing in nature) and stochastic appearing universally in nature. Fractal figures, due to their large complexity, fill space in greater degree than figures of Euclidean geometry. Degree in which figure given fills space, is qualified by fractal dimension, which is most important parameter characterizing fractality of figures. Fractal dimension is estimated by means of variable methods. The most often used are yard-stick method and box-counting method. Following methods: probabilistic, circumference-area, mass scaling and others, are also in use. Fractal dimension measurement is realized by computer programs, which perform measurement on properly converted (digitalized) images of examined structures. From the theory of deterministic chaos point of view, fractals are generated as result of chaodynamic processes. One of processes, that seem to obey laws of deterministic chaos, is carcinogenesis. The question, whether described mathematical methods can be used to estimate microscopic images of neoplasms, appears. Presented in this work results of variable researches concerning creations of mathematical models of neoplasms, investigations of material received from neoplasm tissues as well as of neoplasia growth in vivo or of experiments on neoplasm cells, lead to conclusion, that quantifying of fractal dimension, can perhaps become valuable method helpful in diagnostics of neoplasms. Fractal dimension characterizes examined object, however not always will suffice to its unambiguous identification. Possibly it can serve in tumor grading assessment.

Keywords: fractal, fractal dimension, neoplasma.

Evolutionary Changes of Vertebrate Pineal  Photoreception System

Summary: The pineal – an endocrine gland localized in the vertebrate brain – shares several common features with the retina. Both organs have developed as evaginations from the diencephalon, perform photoreceptive functions, produce melatonin in a light-dependent manner. However, in contrast to the retina, the pineal has undergone considerable evolutionary changes and as a result, the pinealocytes differ in their structure and function among vertebrates. Despite the morphological differences and the loss of the direct photoreceptive capability during phylogeny, the pinealocytes preserve the capability of the expression of many proteins that are specific for phototransduction. As far as their role in the lower vertebrate pineal glands seems to be surely connected with the capability of direct light signal reception, it still remains unclear in mammals. The newest data suggest that they can be directly involved in phototransduction in neonatal rats. In adult mammals they likely take part in other transduction systems.

Key words: photoreception, phototransduction, pineal gland, signaling proteins