A EXPECTATIVA DOS PAIS DIANTE DA EDUCAÇÃO INFANTIL: UM ESTUDO DE CASO

A partir do estudo de caso de uma unidade privada de educação infantil, a presente pesquisa pretendeu investigar, através das expectativas dos pais diante da educação infantil, a influência da herança cultural familiar na trajetória escolar da criança. O interesse teórico de uma pesquisa empírica sobre esse universo é atestado pelo fato de que, conforme Pierre Bourdieu, a valorização e a compreensão da escola, já nos primeiros anos de vida da criança são comuns entre as famílias que possuem um maior nível de escolarização e que conseqüentemente começam a traçar desde cedo a trajetória escolar de seus filhos. Assim, ao estudarmos os pais de alunos de uma unidade privada de educação infantil, estaremos abordando, sobretudo, as expectativas educacionais de famílias da classe média. Apoiados em algumas idéias básicas sobre a conexão entre capital cultural e estratégias educacionais apresentados por Bourdieu, trabalhamos com a hipótese de que as diferentes categorias sociais são desigualmente predispostas a compreender e a valorizar a escolarização em geral, e que este fato está diretamente relacionado ao capital cultural familiar. De acordo com o autor é o volume e o tipo de capital (econômico, social e cultural) que o indivíduo possui que irá definir sua posição na hierarquia social, bem como suas expectativas diante da escola. Nota-se, então, que a cultura de um modo geral opera como um patrimônio de diferenciação de classe.(AU)

UMA ÁNALISE EXEGÉTICA DA PORÇÃO DE MIQUEIAS 2,1-5: A SITUAÇÃO SOCIOECONÔMICA EM JUDÁ E SUAS IMPLICAÇÕES NA HERANÇA DOS CAMPONESES NA SEFELÁ JUDAÍTA NO SÉCULO VIII A.C.

Esta pesquisa procura examinar, à luz da metodologia exegética, a perícope de Miqueias 2,1-5, a fim de reconstruir o cenário no qual emergiu a dura crítica social do profeta. O texto apresenta, em sua análise literária, características de um dito profético coeso, em estilo poético. Sua estrutura encontra-se dividida em duas unidades (denúncia e castigo), sendo que cada uma das unidades possui outras duas subunidades (genérica e específica). O gênero literário harmoniza-se com um dito profético de julgamento geralmente conhecido como oráculo ai . A análise da dimensão histórica situa o acontecimento fundante em 701 a.C., na Sefelá judaíta. Numa análise investigativa do conteúdo da denúncia norteado pelo modelo teórico do modo de produção tributário, observa-se um conflito entre dois grupos. Nesse conflito, Miqueias faz uma acusação a um grupo de poder em Judá que planeja e executa ações criminosas contra a herança camponesa. O castigo descreve a conspiração e o plano divino contra esse grupo de poder. Javé havia planejado um mal idêntico ao que eles haviam cometido, desonra e privação de suas possessões. Os valores culturais de honra e vergonha subjazem a esse oráculo. Por descumprirem seus deveres junto a Javé e ao povo, os criminosos perderiam todos os seus direitos e, sobretudo, a honra perante a própria comunidade. Com base no modelo teórico do modo de produção tributário, constata-se que, na situação social em Judá no oitavo século, prevalecia um conflito entre campo e cidade. As comunidades aldeãs pagavam tributo à cidade em forma de produtos e serviços. A excessiva arrecadação de tributo e as falhas no sistema de ajuda mútua forçaram os indivíduos e famílias a contrair dívidas, a hipotecar suas terras herdadas dos pais e eventualmente perdê-las. O profeta Miqueias é o porta-voz do protesto da classe campesina que resolve reagir aos desmandos praticados pela elite citadina. Para ele, Javé escuta a queixa dos que estão sendo oprimidos e intervém na história tomando o partido do oprimido.(AU)

UMA ÁNALISE EXEGÉTICA DA PORÇÃO DE MIQUEIAS 2,1-5: A SITUAÇÃO SOCIOECONÔMICA EM JUDÁ E SUAS IMPLICAÇÕES NA HERANÇA DOS CAMPONESES NA SEFELÁ JUDAÍTA NO SÉCULO VIII A.C.

Esta pesquisa procura examinar, à luz da metodologia exegética, a perícope de Miqueias 2,1-5, a fim de reconstruir o cenário no qual emergiu a dura crítica social do profeta. O texto apresenta, em sua análise literária, características de um dito profético coeso, em estilo poético. Sua estrutura encontra-se dividida em duas unidades (denúncia e castigo), sendo que cada uma das unidades possui outras duas subunidades (genérica e específica). O gênero literário harmoniza-se com um dito profético de julgamento geralmente conhecido como oráculo ai . A análise da dimensão histórica situa o acontecimento fundante em 701 a.C., na Sefelá judaíta. Numa análise investigativa do conteúdo da denúncia norteado pelo modelo teórico do modo de produção tributário, observa-se um conflito entre dois grupos. Nesse conflito, Miqueias faz uma acusação a um grupo de poder em Judá que planeja e executa ações criminosas contra a herança camponesa. O castigo descreve a conspiração e o plano divino contra esse grupo de poder. Javé havia planejado um mal idêntico ao que eles haviam cometido, desonra e privação de suas possessões. Os valores culturais de honra e vergonha subjazem a esse oráculo. Por descumprirem seus deveres junto a Javé e ao povo, os criminosos perderiam todos os seus direitos e, sobretudo, a honra perante a própria comunidade. Com base no modelo teórico do modo de produção tributário, constata-se que, na situação social em Judá no oitavo século, prevalecia um conflito entre campo e cidade. As comunidades aldeãs pagavam tributo à cidade em forma de produtos e serviços. A excessiva arrecadação de tributo e as falhas no sistema de ajuda mútua forçaram os indivíduos e famílias a contrair dívidas, a hipotecar suas terras herdadas dos pais e eventualmente perdê-las. O profeta Miqueias é o porta-voz do protesto da classe campesina que resolve reagir aos desmandos praticados pela elite citadina. Para ele, Javé escuta a queixa dos que estão sendo oprimidos e intervém na história tomando o partido do oprimido.(AU)

Polyploid formation created unique avenues for response to selection in Gossypium (cotton)

A detailed restriction fragment length polymorphism map was used to determine the chromosomal locations and subgenomic distributions of quantitative trait loci (QTLs) segregating in a cross between cultivars of allotetraploid (AADD) Gossypium hirsutum (“Upland” cotton) and Gossypium barbadense (“Sea Island,” “Pima,” or “Egyptian” cotton) that differ markedly in the quality and quantity of seed epidermal fibers. Most QTLs influencing fiber quality and yield are located on the “D” subgenome, derived from an ancestor that does not produce spinnable fibers. D subgenome QTLs may partly account for the fact that domestication and breeding of tetraploid cottons has resulted in fiber yield and quality levels superior to those achieved by parallel improvement of “A” genome diploid cottons. The merger of two genomes with different evolutionary histories in a common nucleus appears to offer unique avenues for phenotypic response to selection. This may partly compensate for reduction in quantitative variation associated with polyploid formation and be one basis for the prominence of polyploids among extant angiosperms. These findings impel molecular dissection of the roles of divergent subgenomes in quantitative inheritance in many other polyploids and further exploration of both “synthetic” polyploids and exotic diploid genotypes for agriculturally useful variation.

The universal ancestor

A genetic annealing model for the universal ancestor of all extant life is presented; the name of the model derives from its resemblance to physical annealing. The scenario pictured starts when “genetic temperatures” were very high, cellular entities (progenotes) were very simple, and information processing systems were inaccurate. Initially, both mutation rate and lateral gene transfer levels were elevated. The latter was pandemic and pervasive to the extent that it, not vertical inheritance, defined the evolutionary dynamic. As increasingly complex and precise biological structures and processes evolved, both the mutation rate and the scope and level of lateral gene transfer, i.e., evolutionary temperature, dropped, and the evolutionary dynamic gradually became that characteristic of modern cells. The various subsystems of the cell “crystallized,” i.e., became refractory to lateral gene transfer, at different stages of “cooling,” with the translation apparatus probably crystallizing first. Organismal lineages, and so organisms as we know them, did not exist at these early stages. The universal phylogenetic tree, therefore, is not an organismal tree at its base but gradually becomes one as its peripheral branchings emerge. The universal ancestor is not a discrete entity. It is, rather, a diverse community of cells that survives and evolves as a biological unit. This communal ancestor has a physical history but not a genealogical one. Over time, this ancestor refined into a smaller number of increasingly complex cell types with the ancestors of the three primary groupings of organisms arising as a result.

The active digestion of uniparental chloroplast DNA in a single zygote of Chlamydomonas reinhardtii is revealed by using the optical tweezer

The non-Mendelian inheritance of organelle genes is a phenomenon common to almost all eukaryotes, and in the isogamous alga Chlamydomonas reinhardtii, chloroplast (cp) genes are transmitted from the mating type positive (mt+) parent. In this study, the preferential disappearance of the fluorescent cp nucleoids of the mating type negative (mt−) parent was observed in living young zygotes. To study the change in cpDNA molecules during the preferential disappearance, the cpDNA of mt+ or mt− origin was labeled separately with bacterial aadA gene sequences. Then, a single zygote with or without cp nucleoids was isolated under direct observation by using optical tweezers and investigated by nested PCR analysis of the aadA sequences. This demonstrated that cpDNA molecules are digested completely during the preferential disappearance of mt− cp nucleoids within 10 min, whereas mt+ cpDNA and mitochondrial DNA are protected from the digestion. These results indicate that the non-Mendelian transmission pattern of organelle genes is determined immediately after zygote formation.

Defective placental vasculogenesis causes embryonic lethality in VHL-deficient mice

Inheritance of an inactivated form of the VHL tumor suppressor gene predisposes patients to develop von Hippel–Lindau disease, and somatic VHL inactivation is an early genetic event leading to the development of sporadic renal cell carcinoma. The VHL gene was disrupted by targeted homologous recombination in murine embryonic stem cells, and a mouse line containing an inactivated VHL allele was generated. While heterozygous VHL (+/−) mice appeared phenotypically normal, VHL −/− mice died in utero at 10.5 to 12.5 days of gestation (E10.5 to E12.5). Homozygous VHL −/− embryos appeared to develop normally until E9.5 to E10.5, when placental dysgenesis developed. Embryonic vasculogenesis of the placenta failed to occur in VHL −/− mice, and hemorrhagic lesions developed in the placenta. Subsequent hemorrhage in VHL −/− embryos caused necrosis and death. These results indicate that VHL expression is critical for normal extraembryonic vascular development.

A CDKN2-like polymorphism in Xiphophorus LG V is associated with UV-B-induced melanoma formation in platyfish–swordtail hybrids

The genetic basis of spontaneous melanoma formation in spotted dorsal (Sd) Xiphophorus platyfish–swordtail hybrids has been studied for decades, and is adequately explained by a two-gene inheritance model involving a sex-linked oncogene, Xmrk, and an autosomal tumor suppressor, DIFF. The Xmrk oncogene encodes a receptor tyrosine kinase related to EGFR; the nature of the DIFF tumor suppressor gene is unknown. We analyzed the genetic basis of UV-B-induced melanoma formation in closely related, spotted side platyfish–swordtail hybrids, which carry a different sex-linked pigment pattern locus, Sp. We UV-irradiated spotted side Xiphophorus platyfish–swordtail backcross hybrids to induce melanomas at frequencies 6-fold higher than occur spontaneously in unirradiated control animals. To identify genetic determinants of melanoma susceptibility in this UV-inducible Xiphophorus model, we genotyped individual animals from control and UV-irradiated experimental regimes using allozyme and DNA restriction fragment length polymorphisms and tested for joint segregation of genetic markers with pigmentation phenotype and UV-induced melanoma formation. Joint segregation results show linkage of a CDKN2-like DNA polymorphism with UV-B-induced melanoma formation in these hybrids. The CDKN2-like polymorphism maps to Xiphophorus linkage group V and exhibits recombination fractions with ES1 and MDH2 allozyme markers consistent with previous localization of the DIFF tumor suppressor locus. Our results indicate that the CDKN2-like sequence we have cloned and mapped is a candidate for the DIFF tumor suppressor gene.

Recurrent invasion and extinction of a selfish gene

Homing endonuclease genes show super-Mendelian inheritance, which allows them to spread in populations even when they are of no benefit to the host organism. To test the idea that regular horizontal transmission is necessary for the long-term persistence of these genes, we surveyed 20 species of yeasts for the ω-homing endonuclease gene and associated group I intron. The status of ω could be categorized into three states (functional, nonfunctional, or absent), and status was not clustered on the host phylogeny. Moreover, the phylogeny of ω differed significantly from that of the host, strong evidence of horizontal transmission. Further analyses indicate that horizontal transmission is more common than transposition, and that it occurs preferentially between closely related species. Parsimony analysis and coalescent theory suggest that there have been 15 horizontal transmission events in the ancestry of our yeast species, through simulations indicate that this value is probably an underestimate. Overall, the data support a cyclical model of invasion, degeneration, and loss, followed by reinvasion, and each of these transitions is estimated to occur about once every 2 million years. The data are thus consistent with the idea that frequent horizontal transmission is necessary for the long-term persistence of homing endonuclease genes, and further, that this requirement limits these genes to organisms with easily accessible germ lines. The data also show that mitochondrial DNA sequences are transferred intact between yeast species; if other genes do not show such high levels of horizontal transmission, it would be due to lack of selection, rather than lack of opportunity.

Global variation in the genetic and biochemical basis of diamondback moth resistance to Bacillus thuringiensis

Insecticidal proteins from the soil bacterium Bacillus thuringiensis (Bt) are becoming a cornerstone of ecologically sound pest management. However, if pests quickly adapt, the benefits of environmentally benign Bt toxins in sprays and genetically engineered crops will be short-lived. The diamondback moth (Plutella xylostella) is the first insect to evolve resistance to Bt in open-field populations. Here we report that populations from Hawaii and Pennsylvania share a genetic locus at which a recessive mutation associated with reduced toxin binding confers extremely high resistance to four Bt toxins. In contrast, resistance in a population from the Philippines shows multilocus control, a narrower spectrum, and for some Bt toxins, inheritance that is not recessive and not associated with reduced binding. The observed variation in the genetic and biochemical basis of resistance to Bt, which is unlike patterns documented for some synthetic insecticides, profoundly affects the choice of strategies for combating resistance.

The terminal tail region of a yeast myosin-V mediates its attachment to vacuole membranes and sites of polarized growth

The Saccharomyces cerevisiae myosin-V, Myo2p, has been implicated in the polarized movement of several organelles and is essential for yeast viability. We have shown previously that Myo2p is required for the movement of a portion of the lysosome (vacuole) into the bud and consequently for proper inheritance of this organelle during cell division. Class V myosins have a globular carboxyl terminal tail domain that is proposed to mediate localization of the myosin, possibly through interaction with organelle-specific receptors. Here we describe a myo2 allele whose phenotypes support this hypothesis. vac15–1/myo2–2 has a single mutation in this globular tail domain, causing defects in vacuole movement and inheritance. Although a portion of wild-type Myo2p fractionates with the vacuole, the myo2–2 gene product does not. In addition, the mutant protein does not concentrate at sites of active growth, the predominant location of wild-type Myo2p. Although deletion of the tail domain is lethal, the myo2–2 gene product retains the essential functions of Myo2p. Moreover, myo2–2 does not cause the growth defects and lethal genetic interactions seen in myo2–66, a mutant defective in the actin-binding domain. These observations suggest that the myo2–2 mutation specifically disrupts interactions with selected myosin receptors, namely those on the vacuole membrane and those at sites of polarized growth.

Mechanisms of β cell death in diabetes: A minor role for CD95

Insulin-dependent diabetes mellitus is an autoimmune disease, under polygenic control, manifested only when >90% of the insulin-producing β cells are destroyed. Although the disease is T cell mediated, the demise of the β cell results from a number of different insults from the immune system. It has been proposed that foremost amongst these effector mechanisms is CD95 ligand-induced β cell death. Using the nonobese diabetic lpr mouse as a model system, we have found, to the contrary, that CD95 plays only a minor role in the death of β cells. Islet grafts from nonobese diabetic mice that carry the lpr mutation and therefore lack CD95 were protected only marginally from immune attack when grafted into diabetic mice. An explanation to reconcile these differing results is provided.

Frequency of migrants and migratory activity are genetically correlated in a bird population: Evolutionary implications

Most migratory bird populations are composed of individuals that migrate and individuals that remain resident. While the role of ecological factors in maintaining this behavioral dimorphism has received much attention, the importance of genetic constraints on the evolution of avian migration has not yet been considered. Drawing on the recorded migratory activities of 775 blackcaps (Sylvia atricapilla) from a partially migratory population in southern France, we tested two alternative genetic models about the relationship between incidence and amount of migratory activity. The amount of migratory activity could be the continuous variable “underlying” the phenotypic expression of migratory urge, or, alternatively, the expression of both traits could be controlled by two separate genetic systems. The distributions of migratory activities in five different cohorts and the inheritance pattern derived from selective breeding experiments both indicate that incidence and amount of migratory activity are two aspects of one trait. Thus, all birds without measurable activity have activity levels at the low end of a continuous distribution, below the limit of expression or detection. The phenotypic dichotomy “migrant–nonmigrant” is caused by a threshold which may not be fixed but influenced both genetically and environmentally. This finding has profound implications for the evolution of migration: the transition from migratoriness to residency should not only be driven by selection favoring resident birds but also by selection for lower migratory activity. This potential for selection on two aspects, residency and migration distance, of the same trait may enable extremely rapid evolutionary changes to occur in migratory behavior.

Somatic and germ cell parasitism in a colonial ascidian: Possible role for a highly polymorphic allorecognition system

A colonial protochordate, Botryllus schlosseri, undergoes a natural transplantation reaction in the wild that results alternatively in colony fusion (chimera formation) or inflammatory rejection. A single, highly polymorphic histocompatibility locus (called Fu/HC) is responsible for rejection versus fusion. Gonads are seeded and gametogenesis can occur in colonies well after fusion, and involves circulating germ-line progenitors. Buss proposed that colonial organisms might develop self/non-self histocompatibility systems to limit the possibility of interindividual germ cell “parasitism” (GCP) to histocompatible kin [Buss, L. W. (1982) Proc. Natl. Acad. Sci. USA 79, 5337–5341 and Buss, L. W. (1987) The Evolution of Individuality (Princeton Univ. Press, Princeton]. Here we demonstrate in laboratory and field experiments that both somatic cell and (more importantly) germ-line parasitism are a common occurrence in fused chimeras. These experiments support the tenet in Buss’s hypothesis that germ cell and somatic cell parasitism can occur in fused chimeras and that a somatic appearance may mask the winner of a gametic war. They also provide an interesting challenge to develop formulas that describe the inheritance of competing germ lines rather than competing individuals. The fact that fused B. schlosseri have higher rates of GCP than unfused colonies additionally provides a rational explanation for the generation and maintenance of a high degree of Fu/HC polymorphism, largely limiting GCP to sibling offspring.

A novel modifier gene for plasma von Willebrand factor level maps to distal mouse chromosome 11

Type 1 von Willebrand disease (VWD), characterized by reduced levels of plasma von Willebrand factor (VWF), is the most common inherited bleeding disorder in humans. Penetrance of VWD is incomplete, and expression of the bleeding phenotype is highly variable. In addition, plasma VWF levels vary widely among normal individuals. To identify genes that influence VWF level, we analyzed a genetic cross between RIIIS/J and CASA/Rk, two strains of mice that exhibit a 20-fold difference in plasma VWF level. DNA samples from F2 progeny demonstrating either extremely high or extremely low plasma VWF levels were pooled and genotyped for 41 markers spanning the autosomal genome. A novel locus accounting for 63% of the total variance in VWF level was mapped to distal mouse chromosome 11, which is distinct from the murine Vwf locus on chromosome 6. We designated this locus Mvwf for “modifier of VWF.” Additional genotyping of as many as 2407 meioses established a high resolution genetic map with gene order Cola1-Itg3a-Ngfr-Mvwf/Gip-Hoxb9-Hoxb1-Cbx·rs2-Cox5a-Gfap. The Mvwf candidate interval between Ngfr and Hoxb9 is ≈0.5 centimorgan (cM). These results demonstrate that a single dominant gene accounts for the low VWF phenotype of RIIIS/J mice in crosses with several other strains. The pattern of inheritance suggests a gain-of-function mutation in a unique component of VWF biosynthesis or processing. Characterization of the human homologue for Mvwf may have relevance for a subset of type 1 VWD cases and may define an important genetic factor modifying penetrance and expression of mutations at the VWF locus.