The IF(1) inhibitor protein of the mitochondrial F(1)F(0)-ATPase

Recent studies on the IF(1) inhibitor protein of the mitochondrial F(1)F(0)-ATPase from molecular biochemistry to possible pathophysiological roles are reviewed. The apparent mechanism of IF(1) inhibition of F(1)F(0)-ATPase activity and the biophysical conditions that influence IF(1) activity are summarized. The amino acid sequences of human, bovine, rat and murine IF(1) are compared and domains and residues implicated in IF(1) function examined. Defining the minimal inhibitory sequence of IF(1) and the role of conserved histidines and conformational changes using peptides or recombinant IF(1) is reviewed. Luft's disease, a mitochondrial myopathy where IF(1) is absent, is described with respect to IF(1) relevance to mitochondrial bioenergetics and clinical observations. The possible pathophysiological role of IF(1) in conserving ATP under conditions where cells experience oxygen deprivation (tumor growth, myocardial ischemia) is evaluated. Finally, studies attempting to correlate IF(1) activity to ATP conservation in myocardial ischemic preconditioning are compared.     

Evidence for a differential functional regulation of the two beta(3)-integrins alpha(V)beta(3) and alpha(IIb)beta(3)

The functional regulation of integrins is a major determinant of cell adhesion, migration and tissue maintenance. The binding of cytoskeletal proteins to various sites of integrin cytoplasmic domains is a key mechanism of this functional regulation. Expression of recombinant integrin alpha(IIb)beta(3) and alpha(M)beta(2) lacking the GFFKR-region in CHO cells results in constitutively activated integrins. In contrast, CHO cells stably expressing either a GFFKR-deleted alpha(V(del))beta(3) or a FF to AA-substituted alpha(V(AA))beta(3) do not reveal a constitutively activated integrin. Adhesion to immobilized fibrinogen is strongly impaired in alpha(V(del))beta(3) or alpha(V(AA))beta(3)-expressing cells, whereas it is not impaired in alpha(IIb)beta(3) and alpha(M)beta(2), both lacking the GFFKR-region. In a parallel plate flow chamber assay, alpha(V)beta(3)-expressing cells adhere firmly to fibrinogen and spread even at shear rates of 15 to 20 dyn/cm(2), whereas alpha(V(del))beta(3) or alpha(V(AA))beta(3) cells are detached at 15 dyn/cm(2). Actin stress fiber formation and focal adhesion plaques containing alpha(V)beta(3) are observed in alpha(V)beta(3) cells but not in alpha(V(del))beta(3) or alpha(V(AA))beta(3)-expressing cells. As an additional manifestation of impaired outside-in signaling, phosphorylation of pp125(FAK) was reduced in these cells. In summary, we report that the GFFKR-region of the alpha(V)-cytoplasmic domain and in particular two phenylalanines are essential for integrin alpha(V)beta(3) function, especially for outside-in signaling. Our results suggest that the two beta(3)-integrins alpha(IIb)beta(3) and alpha(V)beta(3) are differentially regulated via their GFFKR-region.     

Proton-NMR study of the interaction of trans-dichloro-diamine-platinum(II) with poly(I) and poly(I).poly(C)

The fixation of trans-(NH₃)₂Cl₂ Pt(II) to poly(I)·poly(C) at low r_b (< 0.05) leads to the formation of two complexed species. The major species (ca. 82% of bound platinum) involves coordination of platinum to a single hypoxanthine base, while the other species involves coordination of two hypoxanthine bases, which are either far apart on the same strand or on separate poly(I) strands, to the platinum. These same two species are found after reaction with poly(I), as are two other species throughout the entire r_b range studied (r_b = 0–0.30). The latter two species are assigned to trans-Pt bound to two bases on a poly(I) strand with (a) one or (b) two free bases between the two bound bases. These two species, (a) and (b), account for ca. 35% of the bound platinum, although the 1:1 species remains dominant (ca. 55%). These two additional species are observed at high r_b (>0.075) after reaction with poly(I)·poly(C) but as very minor species. They are formed by reaction with melted poly(I) loops. Also at high r_b, we have observed a shifted cytidine H⁵ resonance arising from interaction of trans-Pt with a melted loop of poly(C). Most probably, this arises from an intramolecular poly(I) to poly(C) crosslink. Results from the reaction of trans-Pt with poly(C) are presented for comparison.     

Diplectanidae (Monogenea) parasites of fish of the Kerkennah Islands (Tunisia)

Eleven Diplectanidae (Monogenea) gill parasites from various Sparidae and Serranidae of the Kerkennah Islands are noted. Three new species: Lamellodiscus hilii, L. bidens, L. impervius, parasites of Puntazzo puntazzo (Sparidae) are described.     

Oxydiacetato complexes of thorium(IV), the crystal structures of tetra-aquo bis(oxydiacetato)thorium(IV) hexahydrate and di(sodium nitrate) disodium tris(oxydiacetato)thorium(IV)

The crystal and molecular structures of Th(oda)₂(H₂O)₄·6H₂O (1) and Na₂[Th(oda)₃]·2NaNO₃ (2) (oda = oxydiacetate) have been determined from three-dimensional X-ray diffraction data and refined by least squares to R = 0.049 and Rw = 0.049 for 2265 independent reflections for (1) and to R = 0.024 and Rw = 0.023 for 2196 independent reflections for (2).Crystal parameters are as follows: (1), tetragonal, space group P4₁2₁2, a = 10.335(2), c = 20.709(5) Å and Z = 4; (2), monoclinic, space group C2/c, a = 17.096(5), b = 9.451(2), c = 16.245(4) Å, β = 107.8(1) and Z = 4.In both compounds the thorium atom lies on a crystallographic two-fold axis. The co-ordination number for thorium in (1) is 10 (bicapped square antiprism geometry), the compound is monomeric, the two oda ligands are tridentate to the metal, and four water molecules complete the coordination sphere; in thorium (2) the coordination number is 9 (tricapped trigonal prism geometry) with three oda ligands tridentate to the metal, the [Th(oda)₃]^2? and NO₃^? anions are held together through the sodium ions which are coordinated both to the oda carboxylic oxygens and to the nitrate oxygens.The ThO coordination distances are: in (1) 2.411(8), 2.414(9) for the carboxylic oxygens, 2.479(10) and 2.486(8) for water molecules and 2.697(9) for the etheric oxygen and in (2) 2.384(3), 2.402(4) and 2.402(4) for the carboxylic oxygens, 2.559(5) and 2.562(4) Å for the etheric oxygens.     

On the fauna of chironomidae (Diptera) of the Hrazdan Basin (Armenia)

A faunistic review of larvae and pupae of chironomid midges (Diptera, Chironomidae) from 15 habitats in the Hrazdan River valley (Armenia) is presented. The revealed fauna includes 40 species from 20 genera and 6 families and tribes. Diploid chromosome numbers are specified for 24 species from 13 genera and 4 subfamilies; 23 species from 14 genera and 4 subfamilies are reported from the region for the first time. Predominant oligotrophic status is confirmed for most of the reservoirs studied.     

Proopiomelanocortin (POMC) and testing the phylogenetic position of turtles (Testudines)

Morphological and molecular studies have inferred multiple hypotheses for the phylogenetic relationships of Testudines. The hypothesis that Testudines are the only extant anapsid amniotes and the sister taxon of diapsid amniotes is corroborated by morphological studies, while the hypothesis that Testudines are diapsid amniotes is corroborated by more recent molecular and morphological studies. In this study, the placement of Testudines is tested using the full length cDNA sequence of the polypeptide hormone precursor proopiomelanocortin (POMC). Because only extant taxa have been used, the hypotheses being tested are limited to the following (1) Testudines as the sister taxon of Archosauria, (2) Testudines included in Archosauria and the sister taxon of Crocodilia, (3) Testudines as the sister taxon of Lepidosauria, (4) Testudines as the sister taxon of Sauria, and (5) Testudines as the sister taxon of a monophyletic Mammalia–Sauria clade. Neither Maximum likelihood, Bayesian, or maximum parsimony analyses are able to falsify the hypothesis of (Archosauria (Lepidosauria, Testudines)) and as such is the preferred inference from the POMC data.     

Characterization of divalent cation localization in the minor groove of the A(n)T(n) and T(n)A(n) DNA sequence elements by (1)H NMR spectroscopy and manganese(II)

The localization of Mn(2+) in A-tract DNA has been studied by (1)H NMR spectroscopy using a series of self-complementary dodecamer oligonucleotides that contain the sequence motifs A(n)(n) and T(n)A(n), where n = 2, 3, or 4. Mn(2+) localization in the minor groove is observed for all the sequences that have been studied, with the position and degree of localization being highly sequence-dependent. The site most favored for Mn(2+) localization in the minor groove is near the 5'-most ApA step for both the T(n)A(n) and the A(n)T(n) series. For the T(n)A(n) series, this results in two closely spaced symmetry-related Mn(2+) localization sites near the center of each duplex, while for the A(n)T(n) series, the two symmetry-related sites are separated by as much as one half-helical turn. The degree of Mn(2+) localization in the minor groove of the T(n)A(n) series decreases substantially as the AT sequence element is shortened from T(4)A(4) to T(2)A(2). The A(n)T(n) series also exhibits length-dependent Mn(2+) localization; however, the degree of minor groove occupancy by Mn(2+) is significantly less than that observed for the T(n)A(n) series. For both A(n)T(n) and T(n)A(n) sequences, the 3'-most AH2 resonance is the least broadened of the AH2 resonances. This is consistent with the observation that the minor groove of A-tract DNA narrows in the 5' to 3' direction, apparently becoming too narrow after two base pairs for the entry of a fully hydrated divalent cation. The results that are reported illustrate the delicate interplay that exists between DNA nucleotide sequence, minor groove width, and divalent cation localization. The proposed role of cation localization in helical axis bending by A-tracts is also discussed.     

Feather mites (Acarina) of the parakeet, Melopsittacus undulatus (Shaw) (Aves: Psittacidae)

The parakeet (or budgerigar) has been transported to many regions of the world. Two species of feather mites, Protolichus lunula (Robin) (Pterolichoidea: Pterolichidae) and Dubininia melopsittaci n. sp. (Analgoidea: Xolalgidae), are specific to this host; from distribution records, these ectoparasites probably have been distributed worldwide with their hosts.     

单性木兰属(木兰科)植物的分类学订正

根据对单性木兰属Kmeria(Pierre)Dandy植物标本的研究和野外调查,补充描述了该属的一些形态特征,纠正了前人对该属描述中的一些错误,阐述了保留单性木兰属的理由,列出了分种检索表,将焕镛木属Woon-youngiaLaw和单性木兰组MagnoliaLinn.sect.Kmeria(Pierre)Figlar&Noot.作为单性木兰属的新异名,将焕镛木Woonyoungiaseptentrionalis(Dandy)Law和广西木兰MagnoliakwangsiensisFiglar&Noot.作为单性木兰KmeriaseptentrionalisDandy的新异名。     

The role of the CPNKEKEC sequence in the beta(2) subunit I domain in regulation of integrin alpha(L)beta(2) (LFA-1)

The alpha(L) I (inserted or interactive) domain of integrin alpha(L)beta(2) undergoes conformational changes upon activation. Recent studies show that the isolated, activated alpha(L) I domain is sufficient for strong ligand binding, suggesting the beta(2) subunit to be only indirectly involved. It has been unclear whether the activity of the alpha(L) I domain is regulated by the beta(2) subunit. In this study, we demonstrate that swapping the disulfide-linked CPNKEKEC sequence (residues 169-176) in the beta(2) I domain with a corresponding beta(3) sequence, or mutating Lys(174) to Thr, constitutively activates alpha(L)beta(2) binding to ICAM-1. These mutants do not require Mn(2+) for ICAM-1 binding and are insensitive to the inhibitory effect of Ca(2+). We have also localized a component of the mAb 24 epitope (a reporter of beta(2) integrin activation) in the CPNKEKEC sequence. Glu(173) and Glu(175) of the beta(2) I domain are identified as critical for mAb 24 binding. Because the epitope is highly expressed upon beta(2) integrin activation, it is likely that the CPNKEKEC sequence is exposed or undergoes conformational changes upon activation. Deletion of the alpha(L) I domain did not eliminate the mAb 24 epitope. This confirms that the alpha(L) I domain is not critical for mAb 24 binding, and indicates that mAb 24 detects a change expressed in part in the beta(2) subunit I domain. These results suggest that the CPNKEKEC sequence of the beta(2) I domain is involved in regulating the alpha(L) I domain.     

Fine Structure of the Organ of Bellonci (SPX) in Boreomysis arctica (Kroyer) (Crustacea, Mysidacea)

The organ of Bellonci (oB) in Boreomysis arctica (Krøyer) is described. The fine structure of the organ is found to agree with that of the oB among other investigated peracarideans. The difficulties met by Chaigneau in 1971 when homologizing the organs in B. arctica and in the Isopoda have been eliminated. Into the cavity of the oB, (probably) sensory neurones protrude. The perikarya of the neurones are found in the wall of the oB. On the dendrites there are subterminal dendritic swellings from which dendritic branches and cilia arise. The branching dendrites are characteristic of the oB in B. arctica. Also the cilia branch, thus increasing the amount of sensory membranes in the organ.     

Structural requirements of echistatin for the recognition of alpha(v)beta(3) and alpha(5)beta(1) integrins

There are key differences between the amino acid residues of the RGD loops and the C termini of echistatin, a potent antagonist of alpha(IIb)beta(3), alpha(v)beta(3) and alpha(5)beta(1), and eristostatin, a similar disintegrin selectively inhibiting alpha(IIb)beta(3). In order to identify echistatin motifs required for selective recognition of alpha(v)beta(3) and alpha(5)beta(1) integrins, we expressed recombinant echistatin, eristostatin, and 15 hybrid molecules. We tested them for their ability to inhibit adhesion of different cell lines to fibronectin and von Willebrand factor and to express ligand-induced binding site epitope. The results showed that Asp(27) and Met(28) support recognition of both alpha(v)beta(3) and alpha(5)beta(1). Replacement of Met(28) with Asn completely abolished echistatin's ability to recognize each of the integrins, while replacement of Met(28) with Leu selectively decreased echistatin's ability to recognize alpha(5)beta(1) only. Eristostatin in which C-terminal WNG sequence was substituted with HKGPAT exhibited new activity with alpha(5)beta(1), which was 10-20-fold higher than that of wild type eristostatin. A hypothesis is proposed that the C terminus of echistatin interacts with separate sites on beta(1) and beta(3) integrin molecules.     

Phylloceras (Hypophylloceras) (Ammonoidea) from the Turonian of North Germany

PalZ - Representatives of the Phylloceratida are described from the Turonian of North Germany for the first time. The specimens are referred toPhylloceras (Hypophylloceras) sp. All phylloceratids...     

On the respiratory quotient (RQ) of termites (Insecta: Isoptera)

The respiratory quotient (RQ) at 28 degrees C was determined by Warburg manometry in 23 species of termites from the Mbalmayo Forest Reserve (Cameroon) and three sub-tropical species cultured under laboratory conditions in the U.K. or freshly collected in Australia. The data are tabulated with other recently reported RQs (determined by manometry or GC) and with measured CH(4) emission rates to provide a survey of 29 species covering both lower and higher termites in all major trophic (functional) categories. In all species, except the wood-feeding Coptotermes acinaciformis and the soil-feeding Cubitermes fungifaber, the observed mean values (with manometry corrected for known fluxes of H(2) and CH(4)) were at or well above 1.00. Soil-feeding forms (except C. fungifaber) generally showed a high apparent RQ (not corrected for H(2)), with nine species (out of 13) above 1.20 and six species above 1.30. Well-replicated laboratory experiments with Reticulitermes lucifugus showed that there was a tendency for RQ to fall with time over a 4-h incubation, although remaining greater than 1.00.The observed RQs are consistent with carbohydrate being the principal substrate supporting respiration in all trophic and taxonomic categories, with little or no contribution from the degradation of lignin or other polyaromatic materials. However, in many species (especially soil-feeders), the observed RQ is greater than that expected from known fluxes of O(2), CO(2) and CH(4) on the assumption that carbohydrate is the respiratory substrate. This presupposes that there is a large hydrogen sink (additional to CH(4) production), possibly the emission of H(2) gas, and/or the existence of unresolved digestive mechanisms or electron routings. Uncertainties in the use of manometry with termites are discussed.     

Transmembrane signal transduction of the alpha(IIb)beta(3) integrin

Integrins are composed of noncovalently bound dimers of an alpha- and a beta-subunit. They play an important role in cell-matrix adhesion and signal transduction through the cell membrane. Signal transduction can be initiated by the binding of intracellular proteins to the integrin. Binding leads to a major conformational change. The change is passed on to the extracellular domain through the membrane. The affinity of the extracellular domain to certain ligands increases; thus at least two states exist, a low-affinity and a high-affinity state. The conformations and conformational changes of the transmembrane (TM) domain are the focus of our interest. We show by a global search of helix-helix interactions that the TM section of the family of integrins are capable of adopting a structure similar to the structure of the homodimeric TM protein Glycophorin A. For the alpha(IIb)beta(3) integrin, this structural motif represents the high-affinity state. A second conformation of the TM domain of alpha(IIb)beta(3) is identified as the low-affinity state by known mutational and nuclear magnetic resonance (NMR) studies. A transition between these two states was determined by molecular dynamics (MD) calculations. On the basis of these calculations, we propose a three-state mechanism.     

Structure-activity relationship of cyclic peptide penta-c[Asp-His(6)-DPhe(7)-Arg(8)-Trp(9)-Lys]-NH(2) at the human melanocortin-1 and -4 receptors: His(6) substitution

A series of MT-II related cyclic peptides, based on potent but non-selective hMC4R agonist (Penta-c[Asp-His(6)-DPhe(7)-Arg(8)-Trp(9)-Lys]-NH(2)) was prepared in which His(6) residue was systematically substituted. Two of the most interesting peptides identified in this study are Penta-c[Asp-5-ClAtc-DPhe-Arg-Trp-Lys]-NH(2) and Penta-c[Asp-5-ClAtc-DPhe-Cit-Trp-Lys]-NH(2) which are potent hMC4R agonists and are either inactive or weak partial agonists (not tested for their antagonist activities) in hMC1R, hMC3R and hMC5R agonist assays.     

Stereo-structural prediction and IR-characteristic band assignment of amorphous protonated forms of homodipeptides (L)-Phe-(L)-Phe, (L)-Trp-(L)-Trp, (L)-Tyr-(L)-Tyr and the neutral - (L)-Trp-(L)-Trp. Ab initio approximation and solid-state linear-polarized IR-spectroscopy

Stereo-structures of protonated (L)-phenylalanine ((L)-Phe), (L)-tyrosine ((L)-Tyr) and (L)-tryptophan ((L)-Trp) containing homodipeptides ((L)-Tyr-(L)-Tyr, (L)-Phe-(L)-Phe, (L)-Trp-(L)-Trp) are carried out by ab initio calculations. The obtained data in gas phase are compared with experimental ones, received by linear-dichroic infrared (IR-LD) spectroscopy of solids, oriented as suspension in nematic mesophase. An observation of a good correlation between theoretical and spectroscopic geometry parameters established and illustrated the possibilities of this complex study approach for the prediction of the stereo-structures in compounds in solid state. The protonation leads to little variance in the bond lengths and angles, expecting the COO(-) fragment, where a distortion of equalized COO(-) bond lengths, stabilizing a C=O double bond and C-O(H) one is established. Significant deviations of the dihedral angles as a result of the protonation are obtained in the skeletal aliphatic and amide- fragments. In (L)-Tyr-(L)-Tyr and (L)-Phe-(L)-Phe, a deviation of O=C-N-H torsion angle about 10-14(0) is predicted. The calculations show a trans-amide configuration in (L)-Trp-(L)-Trp and a cis-one after its protonation.     

Kasimovian (Upper Pennsylvanian) Conodonts of the Shcherbatovka Section (Oka-Tsna Swell)

Paleontological Journal - Kasimovian (Upper Pennsylvanian) conodonts are studied from the Shcherbatovka section (Oka-Tsna Swell, Ryazan Region). The Khamovnikian and Dorogomilovian substages are...