Variation in the cell cycle time in the crypts of lieberkühn of the mouse

The durations of the phases of the cell cycle were measured at different levels in the jejunal crypts of male Balb/c mice. A mean cell cycle time of 12.3 h was found for the whole crypt. In cell positions 1 and 2, the cell cycle time was 16.7 h, and this time steadily decreased to a value of between 10 and 11 h for cell positions above 11. It is concluded that basally situated crypt cells in the mouse are cycling relatively slowly, and that they form the functional stem cell pool for the crypt. These cells may also compose the potential stem cell pool which repopulates the crypt after death of proliferative cells.     

Change in the power of EEG activity in the α range in response to tonic nociceptive stimulation of the distal joint of the little finger

Examination of 12 healthy volunteers aged 20–56 years was performed to study the EEG changes caused by a tonic squeeze of the distal joint of the little finger of the left and then the right hand. This stimulation caused painful sensations of different intensity (pain on the right was stronger). Spectral power was measured in the ( ₁ (8–10.5 Hz) and (₂ ranges (10.5–13 Hz) under different conditions. Weak pain led to an increase in the power of the (₁ and ₂ ranges in the occipital regions. With strong pain, the power of ₁ waves increased bilaterally in the posterior regions (O ₁, O ₂, T ₆), as well as in the left frontal region (F ₃, F ₇). The powers of the ₁ and ₂ ranges substantially increased relative to the background level after the strong nociceptive stimulation ceased. This finding testified to a latent and inertial character of its effect on the -wave parameters.Translated from Fiziologiya Cheloveka, Vol. 31, No. 2, 2005, pp. 77–84.Original Russian Text Copyright © 2005 by Garkavenko, Gorkovenko, Mankovskaya, Shevko, Lyskov, Kostyukov.     

Zooplankton in the ponds with tropical plants in the greenhouses of the Botanical Garden of the Jagiellonian University in Kraków

The presence of P. tetraurelia was found in the pond in "The Palm-House" greenhouse.     

Role of the hydrophobic and charged residues in the 218–226 region of apoA-I in the biogenesis of HDL

We investigated the significance of hydrophobic and charged residues 218–226 on the structure and functions of apoA-I and their contribution to the biogenesis of HDL. Adenovirus-mediated gene transfer of apoA-I[L218A/L219A/V221A/L222A] in apoA-I^−/− mice decreased plasma cholesterol and apoA-I levels to 15% of wild-type (WT) control mice and generated pre-β- and α4-HDL particles. In apoA-I^−/− × apoE^−/− mice, the same mutant formed few discoidal and pre-β-HDL particles that could not be converted to mature α-HDL particles by excess LCAT. Expression of the apoA-I[E223A/K226A] mutant in apoA-I^−/− mice caused lesser but discrete alterations in the HDL phenotype. The apoA-I[218–222] and apoA-I[E223A/K226A] mutants had 20% and normal capacity, respectively, to promote ABCA1-mediated cholesterol efflux. Both mutants had ∼65% of normal capacity to activate LCAT in vitro. Biophysical analyses suggested that both mutants affected in a distinct manner the structural integrity and plasticity of apoA-I that is necessary for normal functions. We conclude that the alteration of the hydrophobic 218–222 residues of apoA-I disrupts apoA-I/ABCA1 interactions and promotes the generation of defective pre-β particles that fail to mature into α-HDL subpopulations, thus resulting in low plasma apoA-I and HDL. Alterations of the charged 223, 226 residues caused milder but discrete changes in HDL phenotype.     

Methylation of the ß-positions of the furan ring in F-acids

Major incubation products in feeding experiments with the sodium salt of 7-(5-butyl-furan-2-yl)heptanoic acid (3) on suspension cultures of Saccharum spec. are the unusual F-acids (4a) and (4b). They possess in contrast to natural monomethyl substituted F-acids a methyl substituent in the 4-position of the furan ring. Unexpectedly, the dimethyl substituted F-acids (4c) and (4d) were found only in very small amounts. The detection and structure elucidation of the methylation products (4a)–(4d) was achieved predominantly by GC-MS analysis of the corresponding tetrahydrofuran derivatives (5a)–(5d).     

Involvement of binding lipoproteins in the absorption and transport of α-tocopherol in the rat

1. Specific lipoproteins binding alpha-tocopherol but not its known metabolites have been isolated and identified from cytosol of rat intestinal mucosa and from serum. 2. A timestudy of the appearance of the orally administered alpha-[(3)H]tocopherol with these lipoproteins indicates that very-low-density lipoprotein of serum acts as a carrier of the vitamin. 3. The involvement of the mucosal lipoprotein in the absorption of the vitamin from the intestine has been inferred from observations on the amounts of alpha-tocopherol in serum of orotic acid-fed rats where release of lipoproteins from the liver to serum is completely inhibited. A considerable decrease in the association of alpha-tocopherol with serum very-low-density lipoprotein under this condition is interpreted to mean that serum lipoproteins are limiting factors for the transport of the vitamin across the intestine and that this is possibly effected by exchange of alpha-tocopherol between serum very-low-density lipoprotein and mucosal lipoprotein.     

Role of vegetation in the variability of water regimes in the Šumava Mts forest

Deviations between observed and simulated discharge in the basins along the borders of the Czech Republic with Austria and Germany provide outputs which enable to follow changes in runoff. The three basins range in area from 100 to 200 km² and the experimental basin Liz with an area of 0.99 km². The selected experimental catchments are situated in or close to the National Park of the ?umava Mts. This region is described also in Tesa? et al. (2006). Results indicate that changes in runoff appear to be related to damages in forest cover caused by wind disasters and insects damages.Daily time series used for simulations are approximately 40 years long and 20 years in the experimental basin. Two different models of the rainfall — runoff process have been used for simulations and the outputs provide comparable results. The models are the conceptual model Sacramento (Burnash, 1995) and the model BROOK’90 (Federer, 1993). The second model distinguishes the details concerning evapotranspiration, including transpiration, rain and snow interception and snow and soil evaporation.The indicated runoff changes seem to be rather complex. After deforestation the volume of runoff generally increases and peak flows of floods are higher, but low flow in rainless periods show complicated courses.     

Modeling the Role of TGF-β in Regulation of the Th17 Phenotype in the LPS-Driven Immune System

Airway exposure levels of lipopolysaccharide (LPS) are known to determine type I versus type II helper T cell induced experimental asthma. While low doses of LPS derive Th2 inflammatory responses, high (and/or intermediate) LPS levels induce Th1- or Th17-dominant responses. The present paper develops a mathematical model of the phenotypic switches among three Th phenotypes (Th1, Th2, and Th17) in response to various LPS levels. In the present work, we simplify the complex network of the interactions between cells and regulatory molecules. The model describes the nonlinear cross-talks between the IL-4/Th2 activities and a key regulatory molecule, transforming growth factor β (TGF-β), in response to high, intermediate, and low levels of LPS. The model characterizes development of three phenotypes (Th1, Th2, and Th17) and predicts the onset of a new phenotype, Th17, under the tight control of TGF-β. Analysis of the model illustrates the mono-, bi-, and oneway-switches in the key regulatory parameter sets in the absence or presence of time delays. The model also predicts coexistence of those phenotypes and Th1- or Th2-dominant immune responses in a spatial domain under various biochemical and bio-mechanical conditions in the microenvironment.     

The Role of the Transport System in the Control of the Source–Sink Relations in Pinus sylvestris

Morphophysiological correlations were studied in medium-aged (20- to 60-year-old) Scots pine trees under the northern taiga conditions. Under various ecological conditions, pine trees developed a well-balanced structure, with close linear relationships between needle and root weight and their cross-section areas in all components of the continuous transport network (the coefficient of determination was between 0.88 and 0.999). When the annual cycle of soluble and insoluble carbohydrate contents was followed in various pine tissues, the total concentrations of soluble and insoluble carbohydrates were maintained at constant and tissue-specific levels, except in the growth period. The maximum level of carbohydrates was observed in all tissues at the beginning of rapid growth, and the minimum, at growth cessation. The qualitative composition and amount of carbohydrates matched the phenological phases of development and were not affected by the ecological growth conditions pertinent to the particular environment. The authors conclude that assimilate synthesis and partitioning are related to structural development, and the state of sink centers determines the attracting capacity, whereas the transport network, from roots to needles, and its conducting capacity are essential for the realization of systemic relationships and the control over growth and development in Pinus sylvestris L.     

Atypical Forms of Cerebral α-Activity in the Case of Lesions in Regulatory Structures of the Human Brain

The results of the EEG study of patients with tumor lesion of diencephalic (29 subjects) and limbic (25 subjects) structures with the focus on the analysis of structural and functional organization of α activity have been summarized. It has been found that diencephalic structure dysfunction is accompanied by disorder of α-rhythm spatial organization in the form of generalization or translocation of its focus to the frontal regions of the cerebral cortex. Distinctive features of “diencephalic” type alteration of α rhythm are determined by predominant integration of the thalamic or hypothalamic structures into the pathological process. Involvement of the limbic structures, especially at early stages of the disease, induces increase in α-rhythm intensity in the temporal region of the affected hemisphere. The nature of the response of the EEG pattern to the functional stress allows identifying it as a “hippocampal α rhythm”. Implementation of the automatic methods of analyzing plays an important role in the identification of these specified pathologic forms of the α rhythm that are often invisible during visual assessment. Detected atypical forms of α rhythm facilitates the interpretation of hemispheric asymmetry of the EEG in patients with cerebral pathology.     

SH groups in the α-naphthyl acetate esterase in the thyroid of the guinea-pig

Summary The -naphthyl acetate esterase in both group I and group II thyroid cells is shown to contain SH groups since there is a decline in activity in both cell groups when certain sulfhydryl reagents [DTNB; 5,5-Dithiobis-(2-nitrobenzoic acid)-AgNO₃-Mersalyl-PCMB (parachloro mercuribenzoate)+urea] are added to the incubation media. Thus the inhibition is by far the greatest in group I cells, which also show the greatest activity after incubation in conventional media, when long fixation and storage times are used. In all cases the inhibiting effect was complete or almost completely reversed if cysteine was added to the incubation media in equivalent concentrations to the SH blocker. There were great differences among the sulfhydryl reagents used in their ability to bring about enzyme inhibition. The alkylating agents NEM (N-ethylmaleimide) and iodoacetamide had no or little effect while PCMB could only inhibit the activity of the -naphthylacetate esterase if the enzyme was denaturated with 5 m urea. The maximal inhibitory effect of PCMB was only obtained when NaCl was added to the incubation media. The most effective inhibitor was AgNO₃.     

Residues 240–250 in the C-Terminus of the Pirh2 Protein Complement the Function of the RING Domain in Self-Ubiquitination of the Pirh2 Protein

Pirh2 is a p53 inducible gene that encodes a RING-H2 domain and is proposed to be a main regulator of p53 protein, thus fine tuning the DNA damage response. Pirh2 interacts physically with p53 and promotes its MDM2-independent ubiquitination and subsequent degradation as well as participates in an auto-regulatory feedback loop that controls p53 function. Pirh2 also self-ubiquitinates. Interestingly, Pirh2 is overexpressed in a wide range of human tumors. In this study, we investigated the domains and residues essential for Pirh2 self-ubiquitination. Deletions were made in each of the three major domains of Pirh2: the N-terminal domain (NTD), Ring domain (RING), and C-terminal domain (CTD). The effects of these deletions on Pirh2 self-ubiquitination were then assessed using in vitro ubiquitination assays. Our results demonstrate that the RING domain is essential, but not sufficient, for Pirh2 self-ubiquitination and that residues 240–250 of the C-terminal domain are also essential. Our results demonstrate that Pirh2 mediated p53 polyubiquitination occurs mainly through the K48 residue of ubiquitin in vitro. Our data further our understanding of the mechanism of Pirh2 self-ubiquitination and may help identify valuable therapeutic targets that play roles in reducing the effects of the overexpression of Pirh2, thus maximizing p53''s response to DNA damage.     

Does the difference in the timing of eclosion of the fruit fly Drosophila melanogaster reflect differences in the circadian organization?

The eclosion rhythm of a laboratory population of Drosophila melanogaster was studied under 12h light, 12h dark (LD 12:12) cycles. Although most of the flies were found to eclose just after “lights on” in LD 12:12, termed within gate (WG) flies, a few flies were found to eclose nearly 10h after peak eclosion, termed outside gate (OG) flies. The circadian parameters of the clocks controlling oviposition rhythms in the WG and the OG flies were estimated to understand the cause of such differences in the timing of eclosion. The distribution of the fraction of individual flies exhibiting single, multiple, and no significant period in the WG flies was significantly different from distribution in the OG flies. Compared to the WG flies, more OG flies were found to exhibit oviposition rhythm with multiple periodicity, whereas more WG flies exhibited an oviposition rhythm with a single significant period. The fraction of flies with arrhythmic oviposition was similar in both the WG and the OG flies. Free-running period τ in constant darkness (DD) and the phase angle difference ψ in LD 12:12 for the oviposition rhythm of WG and OG flies were significantly different. These results suggest that the differences in the time of eclosion between the flies eclosing within the gate and outside the gate of eclosion are probably due to differences in the circadian system controlling eclosion, which is reflected by the differences in their oviposition rhythm. (Chronobiology International, 18(4), 601-612, 2001)     

The rôle of the plastome in evolution of the genusOenothera

In the subgenusEuoenothera, five plastid types can be identified. The same major groups of genome complexes as established byCleland, stand out when attention is focused on the co-operation between genomes and plastomes.Experiments on plastid competition and plastid-genotype compatibility lead to an unambiguous interpretation of phylogenetic relations within the subgenus.Based on a paper read at the XI International Congress of Genetics, The Hague, of which an abstract has been published in theProceedings, Vol. I, p. 131–132 (1963).     

Packing scheme of α-helices in the histone core of the nucleosome

A nucleosome histone core model is presented which is compatible with experimental data. The model consists of 28 α-helices located as predicted by others^1–4. The histone wheel resembles the one proposed by Klug et al.⁵ Most of the helices are packed nearly parallel to the DNA superhelical axis, forming a bandoleer-like structure. About 10 to 20% of the nucleosomal phosphates may be neutralized by positively charged residues in the α-helices. Disregarding the charge of the NH₂-terminals, this is sifficient for the thermodynamic stability of the nucleosome under physiological conditions. The electrostatic charge on the protein surface is assumed to be relatively fixed due to the participation of the corresponding side chains to the hydrophobically packed helices. Thus, DNA wrapping appears to be determined by the core histones not by the histone NH₂-terminals.     

Involvement of β-Carotene in the Antioxidant Defense of the Bacterial Cell

Effects of recombinant -carotene on the resistance of E. coli culture to menadione and paraquat were studied. The presence of -carotene in E. coli cells prevented, to a considerable extent, an increase in superoxide dismutase activity (induced by redox mediators) without affecting the culture growth. These findings suggest that -carotene is involved in the defense of cells against oxidative stress.