Biology and Cognition

O objetivo deste texto e? apresentar a teoria da biologia da cognic?a?o de Maturana e Varela sobre o processo de gerac?a?o de conhecimento nos sistemas vivos. A ge?nese da epistemologia desses cientistas e? que o conhecimento e? uma incessante construc?a?o entre o ser vivo e suas recorrentes interac?o?es com o mundo, num processo que se retroalimenta, estabelecido por uma dina?mica circular. Espera-se, assim, compreender como os seres humanos aprendem. Este texto foi dividido em cinco partes. Na primeira, apresenta-se a mudanc?a para o pensamento siste?mico e complexo; na segunda, algumas hipo?teses de como surgiu a mente; na terceira, apresentam-se algumas comparac?o?es conceituais entre Maturana e Varela e Darwin; na quarta, a releva?ncia cognitiva da organizac?a?o dos seres vivos auto?nomos; na quinta, a construc?a?o do conhecimento social; e, finalmente, na sexta parte, elaboram-se algumas concluso?es acerca da biologia da cognic?a?o.The purpose of this article is to present Maturana and Varela's theory of cognition biology on the process of knowledge generation in living systems. The genesis of these scientists’ epistemology is that knowledge is an endless construction between the living being and its recurrent interactions with the world, in a feedback process which is established by a circular dynamics. This way one hopes to understand how humans learn. This article has been divided into five parts. In the first one, we present the change to systemic and complex thinking; the second part brings some hypotheses on how the mind arose; in the third, we present some conceptual comparisons between Maturana and Varela and Darwin; in the fourth, we present the cognitive relevance of the organization of autonomous living beings; in the fifth, the construction of social knowledge; and finally, in the sixth part, some conclusions about the biology of cognition are elaborated

Biology and Cognition

O objetivo deste texto e? apresentar a teoria da biologia da cognic?a?o de Maturana e Varela sobre o processo de gerac?a?o de conhecimento nos sistemas vivos. A ge?nese da epistemologia desses cientistas e? que o conhecimento e? uma incessante construc?a?o entre o ser vivo e suas recorrentes interac?o?es com o mundo, num processo que se retroalimenta, estabelecido por uma dina?mica circular. Espera-se, assim, compreender como os seres humanos aprendem. Este texto foi dividido em cinco partes. Na primeira, apresenta-se a mudanc?a para o pensamento siste?mico e complexo; na segunda, algumas hipo?teses de como surgiu a mente; na terceira, apresentam-se algumas comparac?o?es conceituais entre Maturana e Varela e Darwin; na quarta, a releva?ncia cognitiva da organizac?a?o dos seres vivos auto?nomos; na quinta, a construc?a?o do conhecimento social; e, finalmente, na sexta parte, elaboram-se algumas concluso?es acerca da biologia da cognic?a?o.The purpose of this article is to present Maturana and Varela's theory of cognition biology on the process of knowledge generation in living systems. The genesis of these scientists’ epistemology is that knowledge is an endless construction between the living being and its recurrent interactions with the world, in a feedback process which is established by a circular dynamics. This way one hopes to understand how humans learn. This article has been divided into five parts. In the first one, we present the change to systemic and complex thinking; the second part brings some hypotheses on how the mind arose; in the third, we present some conceptual comparisons between Maturana and Varela and Darwin; in the fourth, we present the cognitive relevance of the organization of autonomous living beings; in the fifth, the construction of social knowledge; and finally, in the sixth part, some conclusions about the biology of cognition are elaborated

Molecular Marker-Facilitated Investigations of Quantitative Trait Loci in Maize. II. Factors Influencing Yield and Its Component Traits

Because traits such as grain yield are polygenically inherited and strongly influenced by environment, determination of genotypic values from phenotypic expression is not precise and improvement strategies are frequently based on low heritabilities. Increased knowledge of the genetic factors involved in the expression of yield should enhance the improvement of this trait. The objectives of this study were to identify and locate genetic factors (i.e., quantitative trait loci, QTL\u27s) associated with grain yield and 24 yield-related traits in two F2populations of maize (Zea mays L.) using isozyme marker loci. (The populations were generated by selfing the F1, hybrids CO159 ✕ Tx303 and T232 ✕ CM37.) In addition, assessments of the types and magnitudes of gene effects expressed by these QTL\u27s were made. About two-thirds of the associations among 17 to 20 marker loci and the 25 quantitative traits were significant with a large proportion of these at P \u3c 0.001. Proportions of variation accounted for by genetic factors associated with individual marker loci varied from less than 1% to more than 11%. Although individual marker loci accounted for relatively small proportions of the phenotypic variation for these yield-related traits, differences between mean phenotypic values of the two homozygous classes at certain loci were occasionally more than 16% of the population mean. Also, different genomic regions contributed to yield through different subsets of the yield-related traits. Predominant types of gene action varied among loci and among the 25 quantitative traits. For plant grain yield, top ear grain weight, and ear length, the gene action was primarily dominant or overdominant. However, mainly additive gene action was implicated for ear number, kernel row number, and second ear grain weight. Results from these studies should prove to be useful for manipulating QTL\u27s in marker-facilitated selection program

O Popper tardio e a solução de problemas

O objetivo deste artigo é apresentar alguns conceitos da epistemologia evolutiva de Karl Popper. O filósofo, que inicialmente teve uma abordagem inédita da ciência e de seus métodos, apresentou distinções entre teorias cientificas e teorias não cientificas. Numa fase tardia, Popper se aproxima da teoria da seleção natural de Charles Darwin e traça paralelos entre diversos processos cognitivos apresentados pelos organismos vivos. O ponto central de sua tese é que a espécie humana não se limita a uma atitude passiva de recepção de dados provenientes do mundo exterior. Ao contrário, o método utilizado para expansão do conhecimento é de aprendizado que se acumula com a tentativa e erro na resolução de problemas

O Popper tardio e a solução de problemas

O objetivo deste artigo é apresentar alguns conceitos da epistemologia evolutiva de Karl Popper. O filósofo, que inicialmente teve uma abordagem inédita da ciência e de seus métodos, apresentou distinções entre teorias cientificas e teorias não cientificas. Numa fase tardia, Popper se aproxima da teoria da seleção natural de Charles Darwin e traça paralelos entre diversos processos cognitivos apresentados pelos organismos vivos. O ponto central de sua tese é que a espécie humana não se limita a uma atitude passiva de recepção de dados provenientes do mundo exterior. Ao contrário, o método utilizado para expansão do conhecimento é de aprendizado que se acumula com a tentativa e erro na resolução de problemas

Loans for farmers

Cover title.Includes bibliographical references

New Isozyme Systems for Maize (Zea mays L.): Aconitate Hydratase, Adenylate Kinase, NADH Dehydrogenase, and Shikimate Dehydrogenase

Electrophoretic variation and inheritance of four novel enzyme systems were studied in maize (Zea mays L.). A minimum of 10 genetic loci collectively encodes isozymes of aconitate hydratase (ACO; EC 4.2.1.3.), adenylate kinase (ADK; EC 2.7.4.3), NADH dehydrogenase (DIA; EC 1.6.99.-), and shikimate dehydrogenase (SAD; EC 1.1.1.25). At least four loci are responsible for the genetic control of ACO. Genetic data for two of the encoding loci, Aco1 and Aco4, demonstrated that at least two maize ACOs are active as monomers. Analysis of organellar preparations suggests that ACO1 and ACO4 are localized in the cytosolic and mitochondrial subcellular fractions, respectively. Maize ADK is encoded by a single nuclear locus, Adk1, governing monomeric enzymes that are located in the chloroplasts. Two cytosolic and two mitochondrial forms of DIA were electrophoretically resolved. Segregation analyses demonstrated that the two cytosolic isozymes are controlled by separate loci, Dia1 and Dia2, coding for products that are functional as monomers (DIA1) and dimers (DIA2). The major isozyme of SAD is apparently cytosolic, although an additional faintly staining plastid form may be present. Alleles at Sad1 are each associated with two bands that cosegregate in controlled crosses. Linkage analyses and crosses with B-A translocation stocks were effective in determining the map locations of six loci, including the previously described but unmapped locus Acp4. Several of these loci were localized to sparsely mapped regions of the genome. Dia2 and Acp4 were placed on the distal portion of the long arm of chromosome 1, 12.6 map units apart. Dia1 was localized to chromosome 2, 22.2 centimorgans (cM) from B1. Aco1 was mapped to chromosome 4, 6.2 cM from su1. Adk1 was placed on the poorly marked short arm of chromosome 6, 8.1 map units from rgd1. Less than 1% recombination was observed between Glu1 (on chromosome 10) and Sad1. In contrast to many other maize isozyme systems, there was little evidence of gene duplication or of parallel linkage relationships for these allozyme loci

Duplicated Chromosome Segments in Maize (Zea mays L.): Further Evidence from Hexokinase Isozymes

The genetic control of hexokinase isozymes (ATP: d-hexose-6-phosphotransferase, E.C. 2.7.7.1, HEX) in maize (Zea mays L.) was studied by starch gel electrophoresis. Genetic analysis of a large number of inbred lines and crosses indicates that the major isozymes observed are encoded by two nuclear loci, designated Hexl and Hex2. Five active allozymes and one null variant are associated with Hexl, while Hex2 has nine active alleles in addition to a null variant. Alleles at both loci govern the presence of single bands, with no intragenic or intergenic heteromers visible, suggesting that maize HEX\u27s are active as monomers. Organelle preparations demonstrate that the products of both loci are cytosolic. All alleles, including the nulls, segregate normally in crosses. Vigorous and fertile plants were synthesized that were homozygous for null alleles at both loci, suggesting that other hexosephosphorylating enzymes exist in maize that are undetected with our assay conditions. Linkage analyses and crosses with B-A translocation stocks place Hexl on the short arm of chromosome 3, 27 centimorgans from Pgd2 (phosphogluconate dehydrogenase) and Hex2 on the long arm of chromosome 6, approximately 45 centimorgans from Pgdl. It is suggested that the parallel linkages among these two pairs of duplicated genes reflects an evolutionary history involving chromosome segment duplication or polyploidy

The Origin of Cornbelt Maize: The Isozyme Evidence

Historical records show t hat the Midwestern dent corns of the United States originated from hybridization of two landraces, Northern Flint and Southern Dent. We examined the origin of Southern and Midwestern Dents by means of isozyme electrophoresis. Isozyme genotypes were determined for 23 loci in 12 plants each of 32 accessions of Southern Dent. Previously published isozyme data for maize landraces of Mexico and North America and for U.S. Midwestern Dents were included for comparative purposes. The data show that Northern Flint and Southern Dent are among the isozymically most divergent maize landraces. Nei’s genetic identities between populations of these two landraces are very low for conspecific populations (ca. 0.80). Southern Dent of the southeastern U.S. appears closely related to similar dent corns of southern Mexico, supporting a previously published hypothesis that U.S. Southern Dent is largely derived from the dent corns of southern Mexico. The Midwestern Dents, which resulted from crosses of Southern Dent and Northern Flint, are much more like Southern Dent than Northern Flint in their isozyme profile. Similarly, public inbreds show greater affinity to Southern Dent with the exception of sweet corn lines, which resemble Northern Flint in their isozyme allele frequencies. North American public inbreds do not contain appreciable isozymic variation beyond that found in Northern Flint and Southern Dent

Visualization of cortical, subcortical and deep brain neural circuit dynamics during naturalistic mammalian behavior with head-mounted microscopes and chronically implanted lenses

Genetically encoded calcium indicators for visualizing dynamic cellular activity have greatly expanded our understanding of the brain. However, due to light scattering properties of the brain as well as the size and rigidity of traditional imaging technology, in vivo calcium imaging has been limited to superficial brain structures during head fixed behavioral tasks. This limitation can now be circumvented by utilizing miniature, integrated microscopes in conjunction with an implantable microendoscopic lens to guide light into and out of the brain, thus permitting optical access to deep brain (or superficial) neural ensembles during naturalistic behaviors. Here, we describe procedural steps to conduct such imaging studies using mice. However, we anticipate the protocol can be easily adapted for use in other small vertebrates. Successful completion of this protocol will permit cellular imaging of neuronal activity and the generation of data sets with sufficient statistical power to correlate neural activity with stimulus presentation, physiological state, and other aspects of complex behavioral tasks. This protocol takes 6–11 weeks to complete