Aron Arthur Moscona was an Israeli-American developmental biologist whose name is associated with research on cell interactions during embryonic development. His appearance on the international scene dates back to a paper published in 1952, while he was working, together with his wife Haya Sobel Moscona, at the Strangeways Research Laboratory of Cambridge. Together they demonstrated that cells from previously dissociated chick tissues undergo histiotypical and organotypical aggregation in vitro. From 1952 to 1997, Moscona focused his research on cell recognition mechanisms, (...) ultimately demonstrating the role of transmembrane proteins in cellular adhesiveness, tissue segregation, and organ tridimensional assemblage during development. However, who was Aron Moscona before 1952 and what brought him to developmental biology? A Polish Jew who immigrated to Mandatory Palestine in 1933, Moscona belonged to the first generation of biologists formed in the newly established Zoology Department of the Hebrew University. With a particular focus on the Israeli context, the paper reconstructs the evolution of Moscona’s scientific thought by emphasizing the cultural and experimental context of his training and early research at the Hebrew University. The aim is to investigate how local scientific traditions influenced Moscona’s eventual research as well as enabled the relevant experimental innovation he contributed to the field of developmental biology and pathology. The paper can be read both as a scientific biography of Aron Moscona and as a preliminary contribution to the historiography of embryology in the Mandatory Palestine/Israeli context. (shrink)

A central characteristic of living organisms is their agency, that is, their intrinsic activity, both in terms of their basic life processes and their behavior in the environment. This aspect is currently a subject of debate and this article provides an overview of some of the relevant publications on this topic. We develop the argument that agency is immanent in living organisms. There is no life without agency. Even the basic life processes are an intrinsic activity, which we call the (...) organismic level of agency. In addition to this we describe several further levels. These capture different qualities that occur or transform during evolution. In addition to the organismic level, we propose an ontogenetic level, a level of directed agency, directed agency with extended flexibility, and a level that includes the capacities to follow preconceived goals. A further property of organisms is their autonomy. It has been shown that the capacity for autonomy changed during evolution. Here we propose that the two organismic properties autonomy and agency are closely related. Enhanced physiological and behavioral autonomy extends the scope of self-generated, flexible actions and reactions. The increase in autonomy through the evolution of a widened scope of behavioral possibilities and versatility in organisms coincides with extended levels of agency. Especially the human organization, including the sophisticated brain, is the basis for an extended level of agency referring to the capacities to follow preconceived goals. However, it is important for the understanding of the phenomenon of agency not only to assume this latter form, but also to look at the different levels of agency. (shrink)

In 1971, Günter Blobel and David Sabatini proposed a novel and quite speculative schematic model to describe how proteins might reach the proper cellular location. According to their proposal, proteins destined to be secreted from the cell contain a “signal” to direct their release. Despite the fact that Blobel and Sabatini presented their signal hypothesis as a “beautiful idea” not grounded in experimental evidence, they received criticism from other scientists who opposed such speculation. Following the publication of the 1971 model, (...) Blobel persisted in conducting experiments and revising the model to incorporate new data. In fact, over the period of 1975–1984, Blobel and colleagues published five subsequent schematic models of the signal hypothesis, each revised based on new laboratory evidence. I propose that the original 1971 model can be viewed as an epistemic creation. Additionally, analysis of the subsequent schematic diagrams over the period of 1975–1984 allows one to track Blobel’s changing conception of an epistemic object over time. Furthermore, the entire series of schematic diagrams presented by Blobel from 1971 to 1984 allow one to visualize the initial conception and subsequent reworking of a scientific theory. In 1999, Blobel was awarded the Nobel Prize in Physiology or Medicine for his work on the signal hypothesis, which was ultimately supported by experimental evidence gathered after the speculative model was published. (shrink)