RESUMO
BACKGROUND: Miguel Fernández was an Argentinian zoologist who published the first account of obligate polyembryony in armadillos. His contribution is here discussed in relation to his contemporaries, Newman and Patterson, and more recent work. FINDINGS: Fernandez worked on the mulita (Dasypus hybridus). He was able to get early stages before twinning occurred and show it was preceded by inversion of the germ layers. By the primitive streak stage there were separate embryonic shields and partition of the amnion. There was, however, a single exocoelom and all embryos were enclosed in a common set of membranes comprising chorion towards the attachment site in the uterine fundus and inverted yolk sac on the opposite face. He showed that monozygotic twinning did not occur in another armadillo, the peludo (Chaetophractus villosus). CONCLUSIONS: Fernández's work represented a major breakthrough in understanding how twinning occurred in armadillos. His work and that of others is of intrinsic interest to zoologists and has a direct bearing on the origin of monozygotic twins and birth defects in humans.
Assuntos
Anatomia Comparada/história , Tatus/embriologia , Embriologia/história , Desenvolvimento Embrionário , Camadas Germinativas/embriologia , Gemelaridade Monozigótica , Zoologia/história , Animais , Argentina , Tatus/crescimento & desenvolvimento , Tatus/fisiologia , Membranas Extraembrionárias/citologia , Membranas Extraembrionárias/embriologia , Membranas Extraembrionárias/fisiologia , Feminino , Pesquisa em Genética/história , Camadas Germinativas/citologia , Camadas Germinativas/fisiologia , História do Século XX , Masculino , Placentação , Gravidez , Especificidade da Espécie , Saco Vitelino/citologia , Saco Vitelino/embriologia , Saco Vitelino/fisiologiaRESUMO
Se presentan los orígenes de la transgénesis vegetal, analizando los experimentos que llevaron a la obtención de las primeras plantas transgénicas. Aquí se entrecruzan actores, prácticas e intereses que resultan emblemáticos de la biotecnología. Se trata, además, de un caso donde se pone en juego el consenso sobre el sentido de experimentos fundamentales. Estos sucesos permiten ilustrar parte de los conflictos en los que se involucran los organismos genéticamente modificados, pues en torno a estos primeros experimentos los científicos articularán representaciones distintas sobre la transgénesis vegetal, valorando de un modo distinto las anomalías que presentaban los primeros experimentos. De este modo, se analizan los intereses e interpretaciones en torno a los primeros experimentos con plantas transgénicas.
The origins of plant transgenesis are discussed and the experiments that led to the first transgenic plants are analyzed. This process involved a series of actors, practices and interests specific to biotechnology. Consensus about the meaning of fundamental experiments was also at issue here. These events illustrate some of the conflicts related to genetically modified organisms, since scientists had different responses to plant transgenesis at the time of the first experiments, and opinions of the anomalies in those experiments varied. Thus, this article analyzes the interests and interpretations surrounding the first experiments involving transgenic plants.
Assuntos
História do Século XX , Biotecnologia , Plantas Geneticamente Modificadas/anatomia & histologia , Organismos Geneticamente Modificados , Pesquisa em Genética/históriaRESUMO
The question posed by the title is usually answered by saying that the "synthesis" between the theory of evolution by natural selection and classical genetics, which took place in 1930s-40s, would have taken place much earlier if Darwin had been aware of Mendel and his work. What is more, it nearly happened: it would have been enough if Darwin had cut the pages of the offprint of Mendel's work that was in his library and read them! Or, if Mendel had come across Darwin in London or paid him a visit at his house in the outskirts! (on occasion of Mendel's trip in 1862 to that city). The aim of the present paper is to provide elements for quite a different answer, based on further historical evidence, especially on Mendel's works, some of which mention Darwins's studies.
Assuntos
Pesquisa em Genética/história , Seleção Genética , Áustria , Evolução Biológica , Inglaterra , História do Século XIXRESUMO
In this paper I present a model of rational belief change, and I show how to use it to obtain a better insight into the debate about the nature of pneumococcal transformation, genes and DNA that took place in the forties, as a result of Oswald T. Avery's work. The model offers a particular elaboration of the concept of inference to the best explanation, along decision theoretic lines. Within this framework, I distinguish different senses in which Avery's team can be said to have proceeded with caution, thus throwing some light upon a persistent source of disagreement among researchers in the history of genetics. In addition, I explain why we are entitled to say that rival parties such as physicist Maclyn McCarty and biochemist Alfred Mirsky were epistemically rational, in spite of the fact that they reached different conclusions on the basis of the same evidence.