Adenilate pool and thylakoid ATP-synthase content in pea leaves under clinorotation.

It is known that plant resistance to stress factors is connected with energy metabolism. The energy stored in the process of photophosphorylation in the form of ATP is used then to support respiration, transpiration, organic compound synthesis, growth and development as well as to restore cell structure after its damage under extremal environmental factors. Transformation of light energy into chemical energy of ATP is catalyzed by thylakoid membrane enzymatic complex of ATPsynthase-CF1CF0. Its activity and amount in the thylakoid membrane depends on plant growth conditions. The aim of this work was investigation of clinorotation effect on light-induced dynamics of adenyl nucleotides (AMP, ADP and ATP) and estimation of CF1CF0 content in thylakoids of pea leaves grown under slow clinorotation and vertical control.

Effects of photofrin II and light on cellular adenine nucleotides and their modulation.

Effects of photofrin II (PII) and light on the intra cellular nucleotide levels have been investigated using BHK-21 cell line. Results indicate that lower concentrations of photofrin II in dark increases ATP levels in a non linear manner, however, there has been no change in energy charge and levels of other nucleotides. Photoirradiation of PII-treated cells leads to a significant reduction in ATP levels and energy charge along with an increase in ATP breakdown products like ADP and AMP. The phosphorylation potential [ATP]/[ADP][Pi] also reduces upon photoirradiation of PII treated cells. Incubation conditions like pH of the medium and temperature modulate the cellular responses to a great extent.

A novel property of adenine nucleotides: sensitivity to helium-neon laser in mitochondrial reactions.

Consideration is made here of the ability of He-Ne laser light to affect both transport and enzymic reactions by acting on substrates. Adenine nucleotides irradiated with 3 Joules/cm2 fluence (10 mW/cm2 fluence rate) showed altered biochemical behaviour when used as substrates for certain mitochondrial reactions in isolated rat liver mitochondria: ADP/ATP antiport and ATP synthase, which allow for oxidative phosphorylation, and adenylate kinase reaction. In order to determine ATP synthase kinetics a specific method was developed which allows for calculation of ADP phosphorylation rate in intact mitochondria. While no change in ATP synthase kinetics was observed as a result of ADP irradiation, adenine nucleotides proved to be sensitive to He-Ne laser irradiation when their interaction with ADP/ATP carrier and adenylate kinase was considered.

Radiation and thermal stabilities of adenine nucleotides.

We have investigated in detail radiation and thermal stabilities and transformations of adenosine mono- and triphosphates in liquid and frozen solid aqueous solutions within a wide range of absorbed radiation dose (up to 75 kGy) and temperature (up to 160 degrees C). Dephosphorylation is the main pathway of high temperature hydrolysis of adenine nucleotides. Basic thermodynamic and kinetic parameters of this process have been determined. Radiolysis of investigated compounds at room temperature results in scission of N-glycosidic bond with a radiation yield about of 1 mol/100 eV. Solution freezing significantly enhances radiation stability of nucleotides as well as other biomolecules. This circumstance is essential in the discussion of panspermia concepts.

Effects of low-power 632 nm radiation (HeNe laser) on a human cell line: influence on adenylnucleotides and cytoskeletal structures.

HeNe (632 nm) irradiation (5, 15 and 30 min) of an embryonal human cell line (EUE) was used to study the short-term effects on energy charge and the rapid, energy-dependent, remodelling processes of cytoskeletal and adhesion structures. The adenosine triphosphate (ATP) concentration, tested by luminometric and high performance liquid chromatography (HPLC) procedures, is constant after 15 and 30 min of HeNe treatment; the lower phosphorylated nucleotides, i.e. adenosine diphosphate (ADP) and adenosine monophosphate (AMP), change after 30 min in opposite directions: the ADP concentration decreases by 39% whilst that of AMP increases about sixfold. The adenylate energy charge (AEC) decreases by 21.7% in treated EUE cells (AEC = 0.65) in comparison with untreated EUE cells (AEC = 0.83). In HeNe-treated cells, the remodelling of cytoskeletal and adhesion molecules becomes evident after 15 min of treatment. The following events are important: (1) modification of stress fibre assembly and increase in vinculin-containing adhesion plaques; (2) assembly and bundling of intermediate filaments; (3) increase in laminin and L-cell adhesion molecules (L-CAM) expression. The lowered energy charge in irradiated cells is related to the increase in AMP production at the expense of ADP. ATP is dynamically constant despite its requirement in short-time remodelling processes of the cytoskeletal network which are enhanced in irradiated cells.

Further biochemical characterization of rabbit reticulocyte eIF-4B.

In this report, it is shown that eIF-4B exhibits ATP hydrolysis activity in a ribosome-dependent fashion. This activity is significantly enhanced by the addition of eIF-4A and eIF-4F, although neither of these factors, alone or together, display a significant ribosome-dependent ATPase activity. Sepharose-6B gel filtration experiments with combinations of nonlabeled and 14C reductively methylated initiation factors (eIF-4A, eIF-4B, eIF-4F, and eIF-3) provide evidence that both eIF-4B and eIF-4F, but not eIF-4A, interact with ribosomes in the presence of specific factors and ATP. It is not known with which ribosomal subunit(s) these factors interact. In ultraviolet radiation-induced crosslinking studies, an eIF-4A and/or eIF-4F and ATP-dependent crosslinking of eIF-4B to radiolabeled oligo(A)12-18 was observed. Past studies with oxidized-cap mRNA achieved cross-linking of all three of these factors, driven by the specific interaction of eIF-4F p24 with the m7GTP cap structure; this is the first reported instance of only eIF-4B cross-linking to RNA.

Photochemical crosslinking in oligonucleotide-protein complexes between a bromine-substituted 2-5A analog and 2-5A-dependent RNase by ultraviolet lamp or laser.

2',5'-oligoadenylates known as 2-5A [px(A2'p)nA; chi = 2 or 3, n greater than or equal to 2] are produced in interferon-treated cells in response to double-stranded RNA. 2-5A binds with high affinity to a 2-5A-dependent RNase resulting in the cleavage of single-stranded RNA. An efficient, rapid, and extremely sensitive photoaffinity labeling method was developed to facilitate detection of 2-5A-dependent RNase. A bromine-substituted and radioactive derivative of 2-5A, the 5'-monophosphate, p(A2'p)2(br8A2'p)2A3'-[32P]Cp, was synthesized as probe for 2-5A-dependent RNase. Even though this bromine-substituted analog of 2-5A bore no 5'-terminal triphosphate or diphosphate, it bound to 2-5A-dependent RNase with the same high affinity as did 2-5A per se but it was a less effective activator of the RNase under the present assay conditions. The presence of bromine atoms in the 2-5A analog enhanced by more than 200-fold crosslinking to 2-5A-dependent RNase under a uv lamp; many additional polypeptides were also labeled but at much lower levels. Furthermore, using high-intensity uv laser irradiation (308 nm) covalent attachment of the bromine-substituted 2-5A analog to 2-5A-dependent RNase was readily achieved within 10(-6) s.

[Postradiation changes to the systems of active ion transport in the CNS. The content of adenine nucleotides as an index of the energy support for transport]. / Postradiatsionnye izmeneniia sistem aktivnogo transporta ionov v TsNS. Soderzhanie adeninovykh nukleotidov kak pokazatel' énergeticheskogo obespecheniia transporta.

The postirradiation changes in the adenine nucleotide content and energy charge in large hemispheres of rat brain have been investigated. Dose dependent disturbances have been found in the adenine nucleotide system. Mechanisms of changes in the energy status of nerve cells in radiation disease are discussed.

[Molecular nature of the mutations in gene ADE2 in Saccharomyces cerevisiae yeasts. III. Determination of the correlation of the GC AT pairs in genes ADE1 and ADE2]. / Izuchenie molekuliarnoi prirody mutatsii v gene ADE2 u drozhzhei Saccharomyces cerevisiae. Soobshchenie III. Opredelenie sootnosheniia par GTs i AT v genakh ADE1 i ADE2.

Lethal and mutagenic effects and the nature of mutations induced by decay of 32P incorporated into yeast cell DNA as 32P-deoxyguanosine monophosphate (32PdGMP) and 32P-thymidine monophosphate (32P-TMP), were studied. The lethal efficiency per 32P decay is independent of a labelled nucleotide incorporated into DNA. However, the mutagenic efficiency in ADE1, ADE2 genes per 32P decay is approximately 3 times greater for 32PdGMP than for 32P-TMP. This suggests that ADE1, ADE2 genes contain about 3 times more GC base pairs than AT pairs. Variations in a relative frequencies of GC leads to AT and AT leads to GC transitions were obtained depending upon a nucleotide labelled.