ANÁLISE SISTÊMICA DAS RELAÇÕES DE PODER EM GRUPOS DE LIDERANÇA OFICIAL DE IGREJAS DE GOVERNO CONGREGACIONAL: Estudo de Caso em Igrejas Menonitas de Curitiba

A pesquisa a seguir tem o poder como objeto de estudos, especificamente na forma de relações de poder em conselhos diretores (pastoral e administrativo) de igrejas menonitas em Curitiba. A forma presumida de governo dessas igrejas é historicamente congregacional, isto é, as assembléias das respectivas igrejas são supremas e últimas nas deliberações. A metodologia de pesquisa é sociológica, indutiva, funcionalista, com tendências fenomenológicas, tendo como perspectiva principal a teoria sistêmica e seus recursos de pesquisa. A teoria geral dos sistemas orienta os fundamentos da pesquisa, a teoria dos sistemas sociais é o arcabouço da pesquisa. O método de pesquisa é a observação-participante com registros em vídeo e áudio, transcrição, análise e elaboração de conclusões. A técnica de pesquisa citada demonstrou-se eficaz e útil para o levantamento de dados em pesquisas de campo que tratam de grupos e suas funções diferenciadas em agremiações eclesiásticas. Os objetivos buscam identificar a dinâmica sistêmica nas reuniões dos conselhos observados, bem como identificar o processo das relações de poder nos mesmos. As hipóteses lançadas como ponto de partida afirmam que a teoria sistêmica em qualquer perspectiva é observável, bem como os elementos (conselheiros) das relações de poder se demonstram inconscientes de seus atos de poder. As hipóteses principais e secundárias foram confirmadas pela observação-participante, a saber: a pesquisa verifica a hipótese geral de que mesmo igrejas e seus sistemas sociais evidenciam princípios sistêmicos segundo a teoria geral dos sistemas e a teoria dos sistemas sociais de Niklas Luhmann. As hipóteses específicas verificam se os conselheiros dos grupos de liderança evidenciam consciência do poder exercido e do poder implícito em suas funções e papéis; se os grupos formais, eleitos pela assembléia exercem poder de fato ou se existe influência do poder informal; se existe uma correlação, entre o poder formal e as fronteiras rígidas , o poder informal e a fronteira difusa ; se é possível trabalhar preventivamente e interventivamente através do conceito de relações de poder e os princípios sociais sistêmicos. As igrejas menonitas de Curitiba de maneira geral preservam traços de governo congregacional, mas, a transição para estilos de governo pastorcêntricos e autocráticos a partir dos conselhos observados é um fato e parece irreversível. Aparentemente a causalidade desse movimento surge no contexto social metropolitano e suas implicações, mais do que numa mudança estrategicamente planejada pelas lideranças. Portanto, a transição parece ser cultural. Aliás, as transformações sociais das tradições menonitas são diretamente proporcionais à sua inclusão e inculturação no contexto social em que se situam, confirmando assim os princípios sistêmicos da sociedade em geral.(AU)

Differential patterns of acquired virulence genes distinguish Salmonella strains

Analysis of several Salmonella typhimurium in vivo-induced genes located in regions of atypical base composition has uncovered acquired genetic elements that cumulatively engender pathogenicity. Many of these regions are associated with mobile elements, encode predicted adhesin and invasin-like functions, and are required for full virulence. Some of these regions distinguish broad host range from host-adapted Salmonella serovars and may contribute to inherent differences in host specificity, tissue tropism, and disease manifestation. Maintenance of this archipelago of acquired sequence by selection in specific hosts reveals a fossil record of the evolution of pathogenic species.

Prominence of the dopamine D2 short isoform in dopaminergic pathways

As a result of alternative splicing, the D2 gene of the dopamine receptor family exists in two isoforms. The D2 long is characterized by the insertion of 29 amino acids in the third cytoplasmic loop, which is absent in the short isoform. We have produced subtype-specific antibodies against both the D2 short and D2 long isoforms and found a unique compartmentalization between these two isoforms in the primate brain. The D2 short predominates in the cell bodies and projection axons of the dopaminergic cell groups of the mesencephalon and hypothalamus, whereas the D2 long is more strongly expressed by neurons in the striatum and nucleus accumbens, structures targeted by dopaminergic fibers. These results show that the splice variants of the dopamine D2 receptor are differentially distributed and possess distinct functions. The strategic localization of the D2 short isoform in dopaminergic cell bodies and axons strongly suggests that this isoform is the likely dopamine autoreceptor, whereas the D2 long isoform is primarily a postsynaptic receptor.

Replacement of the proximal heme thiolate ligand in chloroperoxidase with a histidine residue

Chloroperoxidase is a versatile heme enzyme which can cross over the catalytic boundaries of other oxidative hemoproteins and perform multiple functions. Chloroperoxidase, in addition to catalyzing classical peroxidative reactions, also acts as a P450 cytochrome and a potent catalase. The multiple functions of chloroperoxidase must be derived from its unique active site structure. Chloroperoxidase possesses a proximal cysteine thiolate heme iron ligand analogous to the P450 cytochromes; however, unlike the P450 enzymes, chloroperoxidase possesses a very polar environment distal to its heme prosthetic group and contains a glutamic acid residue in close proximity to the heme iron. The presence of a thiolate ligand in chloroperoxidase has long been thought to play an essential role in its chlorination and epoxidation activities; however, the research reported in this paper proves that hypothesis to be invalid. To explore the role of Cys-29, the amino acid residue supplying the thiolate ligand in chloroperoxidase, Cys-29 has been replaced with a histidine residue. Mutant clones of the chloroperoxidase genome have been expressed in a Caldariomyces fumago expression system by using gene replacement rather than gene insertion technology. C. fumago produces wild-type chloroperoxidase, thus requiring gene replacement of the wild type by the mutant gene. To the best of our knowledge, this is the first time that gene replacement has been reported for this type of fungus. The recombinant histidine mutants retain most of their chlorination, peroxidation, epoxidation, and catalase activities. These results downplay the importance of a thiolate ligand in chloroperoxidase and suggest that the distal environment of the heme active site plays the major role in maintaining the diverse activities of this enzyme.

A novel multigene family encodes diversified variable regions

Antigen recognition in the adaptive immune response by Ig and T-cell antigen receptors (TCRs) is effected through patterned differences in the peptide sequence in the V regions. V-region specificity forms through genetically programmed rearrangement of individual, diversified segmental elements in single somatic cells. Other Ig superfamily members, including natural killer receptors that mediate cell-surface recognition, do not undergo segmental reorganization, and contain type-2 C (C2) domains, which are structurally distinct from the C1 domains found in Ig and TCR. Immunoreceptor tyrosine-based inhibitory motifs that transduce negative regulatory signals through the cell membrane are found in certain natural killer and other cell surface inhibitory receptors, but not in Ig and TCR. In this study, we employ a genomic approach by using the pufferfish (Spheroides nephelus) to characterize a nonrearranging novel immune-type receptor gene family. Twenty-six different nonrearranging genes, which each encode highly diversified V as well as a V-like C2 extracellular domain, a transmembrane region, and in most instances, an immunoreceptor tyrosine-based inhibitory motif-containing cytoplasmic tail, are identified in an ≈113 kb P1 artificial chromosome insert. The presence in novel immune-type receptor genes of V regions that are related closely to those found in Ig and TCR as well as regulatory motifs that are characteristic of inhibitory receptors implies a heretofore unrecognized link between known receptors that mediate adaptive and innate immune functions.

The human granulocyte-macrophage colony- stimulating factor gene is autonomously regulated in vivo by an inducible tissue-specific enhancer

The granulocyte-macrophage colony-stimulating factor (GM-CSF) gene is part of a cytokine gene cluster and is directly linked to a conserved upstream inducible enhancer. Here we examined the in vitro and in vivo functions of the human GM-CSF enhancer and found that it was required for the correctly regulated expression of the GM-CSF gene. An inducible DNase I-hypersensitive site appeared within the enhancer in cell types such as T cells, myeloid cells, and endothelial cells that express GM-CSF, but not in nonexpressing cells. In a panel of transfected cells the human GM-CSF enhancer was activated in a tissue-specific manner in parallel with the endogenous gene. The in vivo function of the enhancer was examined in a transgenic mouse model that also addressed the issue of whether the GM-CSF locus was correctly regulated in isolation from other segments of the cytokine gene cluster. After correction for copy number the mean level of human GM-CSF expression in splenocytes from 11 lines of transgenic mice containing a 10.5-kb human GM-CSF transgene was indistinguishable from mouse GM-CSF expression (99% ± 56% SD). In contrast, a 9.8-kb transgene lacking just the enhancer had a significantly reduced (P = 0.004) and more variable level of activity (29% ± 89% SD). From these studies we conclude that the GM-CSF enhancer is required for the correct copy number-dependent expression of the human GM-CSF gene and that the GM-CSF gene is regulated independently from DNA elements associated with the closely linked IL-3 gene or other members of the cytokine gene cluster.

Glutathione synthesis is essential for mouse development but not for cell growth in culture

Glutathione (GSH) is a major source of reducing equivalents in mammalian cells. To examine the role of GSH synthesis in development and cell growth, we generated mice deficient in GSH by a targeted disruption of the heavy subunit of γ-glutamylcysteine synthetase (γGCS-HStm1), an essential enzyme in GSH synthesis. Embryos homozygous for γGCS-HStm1 fail to gastrulate, do not form mesoderm, develop distal apoptosis, and die before day 8.5. Lethality results from apoptotic cell death rather than reduced cell proliferation. We also isolated cell lines from homozygous mutant blastocysts in medium containing GSH. These cells also grow indefinitely in GSH-free medium supplemented with N-acetylcysteine and have undetectable levels of GSH; further, they show no changes in mitochondrial morphology as judged by electron microscopy. These data demonstrate that GSH is required for mammalian development but dispensable in cell culture and that the functions of GSH, not GSH itself, are essential for cell growth.

Laser-mediated, site-specific inactivation of RNA transcripts

The biological function of specific gene products often is determined experimentally by blocking their expression in an organism and observing the resulting phenotype. Chromophore-assisted laser inactivation using malachite green (MG)-tagged antibodies makes it possible to inactivate target proteins in a highly restricted manner, probing their temporally and spatially resolved functions. In this report, we describe the isolation and in vitro characterization of a MG-binding RNA motif that may enable the same high-resolution analysis of gene function specifically at the RNA level (RNA-chromophore-assisted laser inactivation). A well-defined asymmetric internal bulge within an RNA duplex allows high affinity and high specificity binding by MG. Laser irradiation in the presence of low concentrations of MG induces destruction of the MG-binding RNA but not of coincubated control RNA. Laser-induced hydrolysis of the MG-binding RNA is restricted predominantly to a single nucleotide within the bulge. By appropriately incorporating this motif into a target gene, transcripts generated by the gene may be effectively tagged for laser-mediated destruction.

Structure-based assignment of the biochemical function of a hypothetical protein: A test case of structural genomics

Many small bacterial, archaebacterial, and eukaryotic genomes have been sequenced, and the larger eukaryotic genomes are predicted to be completely sequenced within the next decade. In all genomes sequenced to date, a large portion of these organisms’ predicted protein coding regions encode polypeptides of unknown biochemical, biophysical, and/or cellular functions. Three-dimensional structures of these proteins may suggest biochemical or biophysical functions. Here we report the crystal structure of one such protein, MJ0577, from a hyperthermophile, Methanococcus jannaschii, at 1.7-Å resolution. The structure contains a bound ATP, suggesting MJ0577 is an ATPase or an ATP-mediated molecular switch, which we confirm by biochemical experiments. Furthermore, the structure reveals different ATP binding motifs that are shared among many homologous hypothetical proteins in this family. This result indicates that structure-based assignment of molecular function is a viable approach for the large-scale biochemical assignment of proteins and for discovering new motifs, a basic premise of structural genomics.

Thyroid hormone receptor β-dependent expression of a potassium conductance in inner hair cells at the onset of hearing

To elucidate the role of thyroid hormone receptors (TRs) α1 and β in the development of hearing, cochlear functions have been investigated in mice lacking TRα1 or TRβ. TRs are ligand-dependent transcription factors expressed in the developing organ of Corti, and loss of TRβ is known to impair hearing in mice and in humans. Here, TRα1-deficient (TRα1−/−) mice are shown to display a normal auditory-evoked brainstem response, indicating that only TRβ, and not TRα1, is essential for hearing. Because cochlear morphology was normal in TRβ−/− mice, we postulated that TRβ regulates functional rather than morphological development of the cochlea. At the onset of hearing, inner hair cells (IHCs) in wild-type mice express a fast-activating potassium conductance, IK,f, that transforms the immature IHC from a regenerative, spiking pacemaker to a high-frequency signal transmitter. Expression of IK,f was significantly retarded in TRβ−/− mice, whereas the development of the endocochlear potential and other cochlear functions, including mechanoelectrical transduction in hair cells, progressed normally. TRα1−/− mice expressed IK,f normally, in accord with their normal auditory-evoked brainstem response. These results establish that the physiological differentiation of IHCs depends on a TRβ-mediated pathway. When defective, this may contribute to deafness in congenital thyroid diseases.

The major murine systemic lupus erythematosus susceptibility locus, Sle1, is a cluster of functionally related genes

The major murine systemic lupus erythematosus (SLE) susceptibility locus Sle1 is syntenic to a chromosomal region linked with SLE susceptibility in multiple human studies. Congenic analyses have shown that Sle1 breaks tolerance to chromatin, a necessary step for full disease induction that can be suppressed by specific modifier loci. In the present study, our fine mapping analysis of the location of Sle1 has determined that three loci within this congenic interval, termed Sle1a, Sle1b, and Sle1c, can independently cause a loss of tolerance to chromatin. Each displays a distinctive profile of serological and cellular characteristics, with T and B cell functions being more affected by Sle1a and Sle1b, respectively. The epistatic interactions of Sle1 with other susceptibility loci to cause severe nephritis cannot be accounted, however, by these three loci alone, suggesting the existence of an additional locus, termed Sle1d. These findings indicate that the potent autoimmune phenotype caused by the Sle1 genomic interval reflects the combined impact of four, separate, susceptibility genes. This level of genetic complexity, combined with similar findings in other systems, supports the possibility that many complex trait loci reflect the impact of polymorphisms in linked clusters of genes with related functions.

Effect of rabies virus infection on gene expression in mouse brain

A variety of molecular genetic approaches were used to study the effect of rabies virus (RV) infection on host gene expression in mouse brain. The down-regulation of gene expression was found to be a major effect of RV infection by using subtraction hybridization. However, a combination of techniques identified approximately 39 genes activated by infection. These included genes involved in regulation of cell metabolism, protein synthesis, synaptic activity, and cell growth and differentiation. Northern blot analysis to monitor temporal activation of several of these genes following infection revealed essentially two patterns of activation: (i) an early response with up-regulation beginning within 3 days after infection and correlating with transcription of RV nuclear protein; and (ii) a late response with enhanced expression occurring at days 6–7 after infection and associated with peak RV replication. The gene activation patterns and the known functions of their products suggest that a number of host genes may be involved in the replication and spread of RV in the brain.

Inactivation of menin, a Smad3-interacting protein, blocks transforming growth factor type β signaling

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by endocrine tumors of parathyroids, pancreatic islets, and anterior pituitary. The MEN1 gene encodes a nuclear protein called menin. In MEN1 carriers inactivating mutations give rise to a truncated product consistent with menin acting as a tumor suppressor gene. However, the role of menin in tumorigenesis and its physiological functions are not known. Here, we show that menin inactivation by antisense RNA antagonizes transforming growth factor type β-mediated cell growth inhibition. Menin interacts with Smad3, and antisense menin suppresses transforming growth factor type β-induced and Smad3-induced transcriptional activity by inhibiting Smad3/4-DNA binding at specific transcriptional regulatory sites. These results implicate a mechanism of tumorigenesis by menin inactivation.

Targeted mutation of the murine arylhydrocarbon receptor nuclear translocator 2 (Arnt2) gene reveals partial redundancy with Arnt

The ubiquitously expressed basic helix–loop–helix (bHLH)-PAS protein ARNT (arylhydrocarbon receptor nuclear transporter) forms transcriptionally active heterodimers with a variety of other bHLH-PAS proteins, including HIF-1α (hypoxia-inducible factor-1α) and AHR (arylhydrocarbon receptor). These complexes regulate gene expression in response to hypoxia and xenobiotics, respectively, and mutation of the murine Arnt locus results in embryonic death by day 10.5 associated with placental, vascular, and hematopoietic defects. The closely related protein ARNT2 is highly expressed in the central nervous system and kidney and also forms complexes with HIF-1α and AHR. To assess unique roles for ARNT2 in development, and reveal potential functional overlap with ARNT, we generated a targeted null mutation of the murine Arnt2 locus. Arnt2−/− embryos die perinatally and exhibit impaired hypothalamic development, phenotypes previously observed for a targeted mutation in the murine bHLH-PAS gene Sim1 (Single-minded 1), and consistent with the recent proposal that ARNT2 and SIM1 form an essential heterodimer in vivo [Michaud, J. L., DeRossi, C., May, N. R., Holdener, B. C. & Fan, C. (2000) Mech. Dev. 90, 253–261]. In addition, cultured Arnt2−/− neurons display decreased hypoxic induction of HIF-1 target genes, demonstrating formally that ARNT2/HIF-1α complexes regulate oxygen-responsive genes. Finally, a strong genetic interaction between Arnt and Arnt2 mutations was observed, indicating that either gene can fulfill essential functions in a dose-dependent manner before embryonic day 8.5. These results demonstrate that Arnt and Arnt2 have both unique and overlapping essential functions in embryonic development.

Arabidopsis thaliana Responses to Mechanical Stimulation Do Not Require ETR1 or EIN21

Plants exposed to repetitive touch or wind are generally shorter and stockier than sheltered plants. These mechanostimulus-induced developmental changes are termed thigmomorphogenesis and may confer resistance to subsequent stresses. An early response of Arabidopsis thaliana to touch or wind is the up-regulation of TCH (touch) gene expression. The signal transduction pathway that leads to mechanostimulus responses is not well defined. A role for ethylene has been proposed based on the observation that mechanostimulation of plants leads to ethylene evolution and exogenous ethylene leads to thigmomorphogenetic-like changes. To determine whether ethylene has a role in plant responses to mechanostimulation, we assessed the ability of two ethylene-insensitive mutants, etr1–3 and ein2–1, to undergo thigmomorphogenesis and TCH gene up-regulation of expression. The ethylene-insensitive mutants responded to wind similarly to the wild type, with a delay in flowering, decrease in inflorescence elongation rate, shorter mature primary inflorescences, more rosette paraclades, and appropriate TCH gene expression changes. Also, wild-type and mutant Arabidopsis responded to vibrational stimulation, with an increase in hypocotyl elongation and up-regulation of TCH gene expression. We conclude that the ETR1 and EIN2 protein functions are not required for the developmental and molecular responses to mechanical stimulation.