Growth stanza in fish life history using otoliths shape: the protandric Centropomus case (Carangaria: Centropomidae)

Morphoanatomical or physiological changes coupled with changes in body size are known as allometric relationships. The objective of this study was to identify the points of growth changes in Centropomus based on otolith morphometry and morphogeometry. For this purpose, 455 individuals of C. undecimalis and 176 of C. parallelus were collected from artisanal fishermen of the coast of the state of Alagoas, Brazil. The sagittal otoliths were measured for length, height, perimeter, area and weighed. The potential and polyphasic models were fitted between total fish length and otolith length. The morphotypes otoliths wen describe by form Fourier descriptors and shape indices. The polyphasic model detected three growth phases. The first stanza for C. undecimalis was at 46.8 cm and the second at 75.9 cm. For C. parallelus, it was at 18.8 cm and at 41.2 cm. Each stanza has a specific otoliths morphotype in both species. The otoliths of C. undecimalis and C. parallelus exhibited ontogenetic allometric changes in their growth pattern with two stanzas changing points. The stanzas corresponded to specific lengths reached by individuals over their life cycles, such as their size at maturity and length at sexual reversion.(AU)

Mudanças morfoanatômicas ou fisiológicas em conjunto com mudanças no tamanho do corpo, são conhecidas como relações alométricas. O objetivo do estudo foi identificar os pontos de mudanças de crescimento de Centropomus com base na morfometria e morfogeometria dos otólitos. Foram coletados 455 indivíduos de C. undecimalis e 176 de C. parallelus, adquiridos com pescadores artesanais do estado de Alagoas, Brasil. Os otólitos sagitta foram medidos quanto ao comprimento, altura, perímetro, área e pesados. Os modelos potencial e polifásico foram ajustados entre o comprimento do peixe e o comprimento do otólito. Os morfotipos de otólitos são descritos por descritores de Fourier e índices de forma. O modelo polifásico detectou três fases de crescimento. A primeira stanza para C. undecimalis foi em 46,8 cm e a segunda em 75,9 cm. Já C. parallelus, a primeira foi em 18,8 cm e segunda em 41,2 cm. Cada stanza possui um morfotipo específico de otólitos em ambas as espécies. Os otólitos de C. undecimalis e C. parallelus exibiram mudanças alométricas ontogenéticas em seu padrão de crescimento com dois pontos de mudança de stanzas. As stanzas corresponderam a comprimentos específicos alcançados por indivíduos ao longo de seus ciclos de vida, como seu tamanho na maturidade e comprimento na reversão sexual.(AU)

A spectroscopic and molecular dynamics study on the aggregation process of a long-acting lipidated therapeutic peptide: the case of semaglutide.

The aggregation properties of semaglutide, a lipidated peptide drug agonist of the Glucagon-like peptide 1 receptor recently approved for the treatment of type 2 diabetes, have been investigated by spectroscopic techniques (UV-Vis absorption, steady-state and time-resolved fluorescence, and electronic circular dichroism) and molecular dynamics simulations. We show that in the micromolar concentration region, in aqueous solution, semaglutide is present as monomeric and dimeric species, with a characteristic monomer-to-dimer transition occurring at around 20 µM. The lipid chain stabilizes a globular morphology of the monomer and dimer species, giving rise to a locally well-defined polar outer surface where the lipid and peptide portions are packed to each other. At very long times, these peptide clusters nucleate the growth of larger aggregates characterized by blue luminescence and a ß-sheet arrangement of the peptide chains. The understanding of the oligomerization and aggregation potential of peptide candidates is key for the development of long acting and stable drugs.

The structure of schizotypal personality traits: a cross-national study.

BACKGROUND: Schizotypal traits are considered a phenotypic-indicator of schizotypy, a latent personality organization reflecting a putative liability for psychosis. To date, no previous study has examined the comparability of factorial structures across samples originating from different countries and cultures. The main goal was to evaluate the factorial structure and reliability of the Schizotypal Personality Questionnaire (SPQ) scores by amalgamating data from studies conducted in 12 countries and across 21 sites. METHOD: The overall sample consisted of 27 001 participants (37.5% males, n = 4251 drawn from the general population). The mean age was 22.12 years (s.d. = 6.28, range 16-55 years). The SPQ was used. Confirmatory factor analysis (CFA) and Multilevel CFA (ML-CFA) were used to evaluate the factor structure underlying the SPQ scores. RESULTS: At the SPQ item level, the nine factor and second-order factor models showed adequate goodness-of-fit. At the SPQ subscale level, three- and four-factor models displayed better goodness-of-fit indices than other CFA models. ML-CFA showed that the intraclass correlation coefficients values were lower than 0.106. The three-factor model showed adequate goodness of fit indices in multilevel analysis. The ordinal α coefficients were high, ranging from 0.73 to 0.94 across individual samples, and from 0.84 to 0.91 for the combined sample. CONCLUSIONS: The results are consistent with the conceptual notion that schizotypal personality is a multifaceted construct and support the validity and utility of SPQ in cross-cultural research. We discuss theoretical and clinical implications of our results for diagnostic systems, psychosis models and cross-national mental health strategies.

Spinal surgery for degenerative lumbar spine disease: Predictors of outcome.

OBJECTIVES: Identify predictors of outcomes for results in Degenerative Lumbar Spine Disease (DLSD). PATIENTS AND METHODS: A retrospective analysis of 164 patients who underwent surgery for DLSD was performed. The study duration was 24 months (January 2013-December 2014). The patients were first evaluated and were assessed for their results regarding the extent of surgery in four groups: patients undergoing surgery for treatment of one segment, two segments, three segments, and four or more segments of DLS. Posteriorly, the same group of patients was divided based on the presence or absence of Dural Tear (DT) during surgery. In addition, the relationship between elderlies and the incidence of surgical site infection (SSI) and reoperation was also analyzed. RESULTS: A total of 193 surgeries were performed on 164 patients (74 males/90 females), with a mean age of 53.18 years old (53.18 ± 17.54). SSI occurred in 7.31% of cases and re-operations due to SSI or because of complications resulting from the first procedure occurred in 11,58% of cases. Results statistically significant were found regarding the incidence of SSI (P=0.05) and the rate of re-operation (p=0.003) in surgeries involving more than three segments. DT is directly related to the rate of re-operation (p=0.0172) and SSI (p=0.0002). Elderly patients were not a predictor of poor outcome, neither to incidence of SSI (p=0.2), nor chance of re-operation (p=0.36). CONCLUSION: Surgeries involving more than three segments are directly related to SSI, incidence of accidental DT and chance of re-operation. The presence of DT during the procedure is presented as a predictor of postoperative SSI and an increase in re-operation rate. Furthermore, elderly patients are not related to a higher risk for SSI and re-operations.

Chemical characterization and surface properties of a new bioemulsifier produced by Pedobacter sp. strain MCC-Z.

A novel biopolymer was described in the form of an extracellular polysaccharide (EPS) by Pedobacter sp. strain MCC-Z, a member of a bacterial genus not previously described as an emulsifier producer. The new biomolecule was extracted, purified and characterized, and its surface and emulsifying properties were evaluated. The purified bioemulsifier, named Pdb-Z, showed high emulsifying activity (E24% = 64%) and reduced the surface tension of water up to 41 mN/m with a critical micelle concentration value of 2.6 mg/mL. The chemical characterization of Pdb-Z was performed using (1)H NMR, FT-IR, HPLC/MS/MS and GC/MS. Pdb-Z was found to contain 67% of carbohydrates, consisting mainly of galactose and minor quantities of talose, 30% of lipids, being pentadecanoic acid the major lipidic constituent, and 3% of proteins. The bioemulsifier was a glycolipids-protein complex with an estimated molecular mass of 10(6)Da. Furthermore, Pdb-Z emulsified pure aliphatic and aromatic hydrocarbons as well as diesel more efficiently than commercial synthetic surfactants, used for comparison. Our results suggest Pdb-Z has interesting properties for applications in remediation of hydrocarbon-contaminated environments and bioremediation processes.

MD simulations of papillomavirus DNA-E2 protein complexes hints at a protein structural code for DNA deformation.

The structural dynamics of the DNA binding domains of the human papillomavirus strain 16 and the bovine papillomavirus strain 1, complexed with their DNA targets, has been investigated by modeling, molecular dynamics simulations, and nuclear magnetic resonance analysis. The simulations underline different dynamical features of the protein scaffolds and a different mechanical interaction of the two proteins with DNA. The two protein structures, although very similar, show differences in the relative mobility of secondary structure elements. Protein structural analyses, principal component analysis, and geometrical and energetic DNA analyses indicate that the two transcription factors utilize a different strategy in DNA recognition and deformation. Results show that the protein indirect DNA readout is not only addressable to the DNA molecule flexibility but it is finely tuned by the mechanical and dynamical properties of the protein scaffold involved in the interaction.

Molecular dynamics of the DNA-binding domain of the papillomavirus E2 transcriptional regulator uncover differential properties for DNA target accommodation.

Papillomaviruses are small DNA tumor viruses that infect mammalian hosts, with consequences from benign to cancerous lesions. The Early protein 2 is the master regulator for the virus life cycle, participating in gene transcription, DNA replication, and viral episome migration. All of these functions rely on primary target recognition by its dimeric DNA-binding domain. In this work, we performed molecular dynamics simulations in order to gain insights into the structural dynamics of the DNA-binding domains of two prototypic strains, human papillomavirus strain 16 and the bovine papillomavirus strain 1. The simulations underline different dynamic features in the two proteins. The human papillomavirus strain 16 domain displays a higher flexibility of the beta2-beta3 connecting loop in comparison with the bovine papillomavirus strain 1 domain, with a consequent effect on the DNA-binding helices, and thus on the modulation of DNA recognition. A compact beta-barrel is found in human papillomavirus strain 16, whereas the bovine papillomavirus strain 1 protein is characterized by a loose beta-barrel with a large number of cavities filled by water, which provides great flexibility. The rigidity of the human papillomavirus strain 16 beta-barrel prevents protein deformation, and, as a consequence, deformable spacers are the preferred targets in complex formation. In contrast, in bovine papillomavirus strain 1, a more deformable beta-barrel confers greater adaptability to the protein, allowing the binding of less flexible DNA regions. The flexibility data are confirmed by the experimental NMR S2 values, which are reproduced well by calculation. This feature may provide the protein with an ability to discriminate between spacer sequences. Clearly, the deformability required for the formation of the Early protein 2 C-terminal DNA-binding domain-DNA complexes of various types is based not only on the rigidity of the base sequences in the DNA spacers, but also on the intrinsic deformability properties of each domain.

Expression of pannexin1 in the CNS of adult mouse: cellular localization and effect of 4-aminopyridine-induced seizures.

The expression pattern of pannexin1, a gene coding for a protein that forms gap junction channels, was studied as both mRNA and protein in the CNS of adult mouse. Pannexin1 was widely expressed in the CNS by neuronal cell types but not glial cells, except for Bergmann glial cells of the cerebellar cortex. Cells positive to Ca-binding proteins, principally parvalbumin, but also calbindin and calretinin, as well as glutamate decarboxylase 67 kDa isoform, were pannexin1-positive. Pannexin1 labeling was found in cells which are known to exhibit spontaneous and synchronous discharge, such as neurons of the inferior olivary complex and the reticular thalamic nucleus, and also in neurons whose electrical activity is not coupled with neighboring cells, such as motoneurons of the spinal cord. The analysis of cellular localization showed puncta that surrounded cell bodies (e.g. the pyramidal cells of hippocampus) or restricted areas inside the cell bodies (e.g. the spinal motoneurons). In Bergmann glial cells the staining was present as fine grains that covered a large part of the cellular surface. Pannexin1 stained cells that previous studies have reported as expressing connexin36, another protein forming gap junction channels. Thus, it was possible that these two proteins could be integrated in the same functions. Since connexin36 expression levels change after seizures, we examined the expression of both pannexin1 and connexin36 in cerebral cortex, hippocampus, cerebellum and brain stem at different time intervals (2, 4 and 8 h) after i.p. injection of 4-aminopyridine, which resulted in systemic seizures. The only modification of the expression levels observed in this study concerned the progressive decrement of the connexin36 in the hippocampus, while pannexin1 expression was unchanged. This finding suggested that pannexin1 and connexin36 are involved in different functional roles or that they are expressed in different cell types and that only those expressing the Cx36 are induced to apoptosis by epileptic seizures.

Identification of a conserved N-capping box important for the structural autonomy of the prion alpha 3-helix: the disease associated D202N mutation destabilizes the helical conformation.

Peptides corresponding to three alpha helices present in the C-terminal region of the human prion protein have been synthesized and their structural autonomy analyzed by circular dichroism (CD) and NMR spectroscopy. The results obtained indicate that the protein fragment corresponding to the alpha 3-helix, in contrast to alpha 1 and alpha 2 peptides, shows a complete structural autonomy. The chemical shifts values found for NH and CHalpha resonance of the isolated alpha 3 peptide, formed by 30 aminoacid residues, were markedly and surprisingly similar to the corresponding values of the alpha 3-helix in the protein. The structural autonomy of the alpha 3-helix is profoundly determined by the presence of the conserved capping box and, in part, by the ionic bond formed between Glu200 and Lys204. On the basis of these observations a novel PrP consensus pattern, centered on the alpha 3-helix region, has been defined. The data indicate that this autonomous and highly conserved region of the PrPc likely plays a critical role in folding and stability. This gives an explanation of why many of pathogenic mutations occur in this part of the molecule, sharing relevant effects on the overall protein conformation. In particular the D202N capping mutation almost completely destabilizes the isolated alpha 3 peptide. While it is well known that the D202N substitution is associated with a GSS disease, the possible structural basis of this fatal pathology has never been investigated. We propose that a lower alpha 3-helical propensity leading to a major destabilization of the PrPc molecule initiates the pathogenic process associated with D202N capping mutation.

Measurement of homonuclear three-bond J(H(N)Halpha) coupling constants in unlabeled peptides complexed with labeled proteins: application to a decapeptide inhibitor bound to the proteinase domain of the NS3 protein of hepatitis C virus (HCV).

A new isotope-filtered experiment has been designed to measure homonuclear three-bond J(H(N)Halpha) coupling constants of unlabeled peptides complexed with labeled proteins. The new experiment is based on the 3D HNHA pulse scheme, and belongs to the 'quantitative J-correlation' type. It has been applied to a decapeptide inhibitor bound to the proteinase domain of the NS3 protein of human hepatitis C virus (HCV).

Improved sensitivity in indirect monitoring of chemical shifts of proton-heteronuclear spin pairs (1H-13C and 1H-15N) in 3D and 4D NMR spectroscopy.

In three-dimensional and four-dimensional experiments on doubly labelled proteins not only heteronuclear (13C or 15N) but also proton (1H) frequencies are often indirectly monitored, rather than being directly observed. In this communication we show how in these experiments by overlaying 1H and heteronuclear evolutions one can obtain decreased apparent relaxation rates of 1H signals, yielding improved sensitivity. The new method applies to spin pairs like 1H-15N, as in amide groups, or 1H-13C, as in methine groups of alpha or aromatic systems.

Sensitivity enhancement of a two-dimensional experiment for the measurement of heteronuclear long-range coupling constants, by a new scheme of coherence selection by gradients.

In this work we present a new pulse sequence for the measurement of long-range heteronuclear coupling constants in which the optimization of coherence selection by pulsed field gradients offers a net increase in sensitivity. This type of experiments is extremely valuable for conformational studies of molecules in natural abundance and in this context the use of gradients is essential for an efficient suppression of (12)C bound proton signals. A comparative analysis of the different gradient schemes available is presented with a conclusive elucidation of the relative sensitivities. Our gradient scheme could be advantageous as a building block for other related experiments.

Inhibitor binding induces active site stabilization of the HCV NS3 protein serine protease domain.

Few structures of viral serine proteases, those encoded by the Sindbis and Semliki Forest viruses, hepatitis C virus (HCV) and cytomegalovirus, have been reported. In the life cycle of HCV a crucial role is played by a chymotrypsin-like serine protease encoded at the N-terminus of the viral NS3 protein, the solution structure of which we present here complexed with a covalently bound reversible inhibitor. Unexpectedly, the residue in the P2 position of the inhibitor induces an effective stabilization of the catalytic His-Asp hydrogen bond, by shielding that region of the protease from the solvent. This interaction appears crucial in the activation of the enzyme catalytic machinery and represents an unprecedented observation for this family of enzymes. Our data suggest that natural substrates of this serine protease could contribute to the enzyme activation by a similar induced-fit mechanism. The high degree of similarity at the His-Asp catalytic site region between HCV NS3 and other viral serine proteases suggests that this behaviour could be a more general feature for this category of viral enzymes.

The solution structure of the N-terminal proteinase domain of the hepatitis C virus (HCV) NS3 protein provides new insights into its activation and catalytic mechanism.

The solution structure of the hepatitis C virus (BK strain) NS3 protein N-terminal domain (186 residues) has been solved by NMR spectroscopy. The protein is a serine protease with a chymotrypsin-type fold, and is involved in the maturation of the viral polyprotein. Despite the knowledge that its activity is enhanced by the action of a viral protein cofactor, NS4A, the mechanism of activation is not yet clear. The analysis of the folding in solution and the differences from the crystallographic structures allow the formulation of a model in which, in addition to the NS4A cofactor, the substrate plays an important role in the activation of the catalytic mechanism. A unique structural feature is the presence of a zinc-binding site exposed on the surface, subject to a slow conformational exchange process.

Structural characterization of the interactions of optimized product inhibitors with the N-terminal proteinase domain of the hepatitis C virus (HCV) NS3 protein by NMR and modelling studies.

The interactions of peptide inhibitors, obtained by the optimization of N-terminal cleavage products of natural substrates, with the protease of human hepatitis C virus (HCV) are characterized by NMR and modelling studies. The S-binding region of the enzyme and the bound conformation of the ligands are experimentally determined. The NMR data are then used as the experimental basis for modelling studies of the structure of the complex. The S-binding region involves the loop connecting strands E2 and F2, and appears shallow and solvent-exposed. The ligand binds in an extended conformation, forming an antiparallel beta-sheet with strand E2 of the protein, with the P1 carboxylate group in the oxyanion hole.

Selective correlation of amide groups to glycine alpha protons and of arginine guanidine groups to delta protons in proteins by multiple quantum spectroscopy.

A new 3D pulse sequence correlates backbone amide proton and nitrogen with alpha proton resonances selectively for glycine residues in a fully doubly labeled (15N, 13C) protein. The excitation of multiple quantum coherences provides optimized resolution and sensitivity. Degenerate alpha proton groups can be promptly recognized. Correlation of guanidine NH groups to delta protons of arginine side chains is also obtained.

The metal binding site of the hepatitis C virus NS3 protease. A spectroscopic investigation.

The NS3 region of the hepatitis C virus encodes for a serine protease activity, which is necessary for the processing of the nonstructural region of the viral polyprotein. The minimal domain with proteolytic activity resides in the N terminus, where a structural tetradentate zinc binding site is located. The ligands being been identified by x-ray crystallography as being three cysteines (Cys97, Cys99, and Cys145) and one histidine residue (His149), which is postulated to coordinate the metal through a water molecule. In this article, we present an analysis of the role of metal coordination with respect to enzyme activity and folding. Using NMR spectroscopy, the resonances of His149 were assigned based on their isotropic shift in a Co(II)-substituted protein. Data obtained with 15N-labeled NS3 protease were compatible with the involvement of the delta-N of His149 in metal coordination. pH titration experiments showed that the cooperative association of at least two protons is required in the protonation process of His149. Changes in the NMR signals of this residue between pH 7 and 5 are interpreted as evidence for a structural change at the metal binding site, which switches from a "closed" to an "open" conformation. Site-directed mutagenesis of His149 has shown the importance of this residue in the metal incorporation pathway and for achieving an active fold. The metal coordination of the protease was also investigated by circular dichroism and electronic absorption spectroscopies using a Co(II)-substituted enzyme. We show evidence for rearrangements of the metal coordination geometry induced by complex formation with an NS4A peptide cofactor. No such changes were observed upon binding to a substrate peptide. Also, CN- and N3- induced Co(II) ligand field perturbations, which went along with an 1.5-fold enhancement of protease activity.

High-resolution solution structure of two members of a conformationally homogeneous combinatorial peptide library based on the classical zinc-finger motif.

We describe the high-resolution structure by NMR of two peptides that belong to a combinatorial library based on the zinc-finger motif. The library represents, to the best of our knowledge, the first example of a conformationally homogeneous peptide library and was obtained by introducing random residues in five positions of the alpha-helical portion of a 26-residue 'consensus' peptide (CP1) belonging to the Cys(2)-Hys2 zinc-finger family. The result was shown to be a highly homogeneous alpha-helical library (Bianchi et al., 1995). The structures of the parent compound (CPI) and of a representative member (CPlm) that was selected by screening the library with a monoclonal antibody are compared in detail as an example of the very high stability of the zinc-finger scaffold upon sequence variability. The two peptides exhibit an extremely high degree of structural similarity. The use of this type of conformationally constrained combinatorial library might represent a step forward in the design of peptidomimetics, as it considerably accelerates the process of the identification of the spatial relationship among the pharmacophoric groups.