A. A. Ukhtomskiĭ and I. P. Pavlov: a controversy or a dialogue?

Pavlov's concept of conditioned reflexes and Ukhtomskii theory of dominanta fall within the biological line in physiology. They unravel the integral adaptive and active nature of the organism behavior in the environment. It is impossible to develop modern concepts about the determinants of goal-directed behavior of animals and voluntary activity of humans without in-depth study of the achievements of these Russian physiological schools which not only formed the methodological basis for the current studies but also directed the way for their further development.     

Regeneration: The origin of cancer or a possible cure?

A better understanding of the forces controlling cell growth will be essential for developing effective therapies in regenerative medicine and cancer. Historically, the literature has linked cancer and tissue regeneration—proposing regeneration as both the source of cancer and a method to inhibit tumorigenesis. This review discusses two powerful regeneration models, the vertebrate urodele amphibians and invertebrate planarians, in light of cancer regulation. Urodele limb and eye lens regeneration is described, as well as the planarian's emergence as a molecular and genetic model system in which recent insights begin to molecularly dissect cancer and regeneration in adult tissues.     

The euryarchaeotes, a subdomain of Archaea, survive on a single DNA polymerase: fact or farce?

Archaea is now recognized as the third domain of life. Since their discovery, much effort has been directed towards understanding the molecular biology and biochemistry of Archaea. The objective is to comprehend the complete structure and the depth of the phylogenetic tree of life. DNA replication is one of the most important events in living organisms and DNA polymerase is the key enzyme in the molecular machinery which drives the process. All archaeal DNA polymerases were thought to belong to family B. This was because all of the products of pol genes that had been cloned showed amino acid sequence similarities to those of this family, which includes three eukaryal DNA replicases and Escherichia coli DNA polymerase II. Recently, we found a new heterodimeric DNA polymerase from the hyperthermophilic archaeon, Pyrococcus furiosus. The genes coding for the subunits of this DNA polymerase are conserved in the euryarchaeotes whose genomes have been completely sequenced. The biochemical characteristics of the novel DNA polymerase family suggest that its members play an important role in DNA replication within euryarchaeal cells. We review here our current knowledge on DNA polymerases in Archaea with emphasis on the novel DNA polymerase discovered in Euryarchaeota.     

The origins of entasis: illusion, aesthetics or engineering?

A typical characteristic of columns in Doric temples is entasis; a slight convexity in the body of a column. Often, and particularly in guide-books, it is suggested that entasis is intended to compensate for an illusion of concavity in columns with truly straight sides. We have investigated whether any such visual illusion exists, both in parallel sided and in tapering columns in a series of experiments, finding little evidence to support any illusion-compensation theory. Further, we explored the possibility that entasis was employed for purely aesthetic reasons, but the results do not support this conclusion. Finally, evidence supporting an engineering role for entasis is presented.     

The Florey Lecture, 1982. Discovery: accident or design?

The lecturer reviews the extent to which his own experiments on muscle have followed the course intended when they were planned. His observations on changes in the striation pattern were designed to reinvestigate the formation of 'contraction bands', repeatedly observed in the 19th century but neglected more recently. This phenomenon was indeed seen during active shortening, but the most important outcome consisted of two quite unexpected observations which suggested the existence of a sliding-filament system. Experiments on local activation were planned on the hypothesis that activation was conducted inward from the surface membrane along the Z line. This was apparently confirmed in the first experiments, on fibres from frog muscle, but experiments on muscle fibres from other animals, together with improvements in electron microscope technique, showed that this was a coincidence and that the Z line as such is not involved. Investigation of the transient changes of tension when a stimulated muscle fibre is suddenly shortened required a series of exploratory measurements before a useful hypothesis could be formulated. Some personal factors that have motivated scientists, including Lord Florey himself, are discussed.     

The emergence of technology: A cultural step or long-term evolution?

There are two hypotheses to explain the emergence of the technical behaviour: (1) a sudden and fast appearance across the African continent; (2) a long period of emergence and consolidation before it began to spread. We defend this second hypothesis and suggest that the hominid project started around 3 Myr ago, with a ‘biofunctional’ stage. Later than 2.5 Myr, the ‘biomorphotechnical’ stage began (Mode 1), and, at around 1.7 Myr, another stage emerged and developed: the ‘biopotential’ stage (Mode 2). All these stages consist of a two-part process: innovation/emergence, and socialization/generalization of a technical mode.     

Interpreting Schizophrenia: Construal or Construction? A Reply to Robert J. Barrett

Culture, Medicine, and Psychiatry -     

Rural Poor Economies and Foreign Investors: An Opportunity or a Risk?

In the current age of commercial and financial openness, remote and poor local economies are becoming increasingly exposed to inflows of external capital. The new investors - enjoying lower credit constraints than local dwellers - might play a propulsive role in local development. At the same time, inflows of external capital can have negative impacts on local natural resource-dependent activities. We analyze a two-sector model where both sectors damage the environment, but only that of domestic producers relies on natural resources. We assess under which conditions the coexistence of the two sectors is compatible with sustainability, defined as convergence to a stationary state characterized by a positive stock of the natural resource. Moreover, we find that capital inflows can be stimulated by an increase in the pollution intensity of incoming activities, but also in the pollution intensity of the domestic sector; in both cases, capital inflows generate environmental degradation and a decrease in welfare for the local population. Finally, we show that a reduction in the cost of capital for external investors and the consequent capital inflows have the effect to increase wages, local investments and welfare of the local populations only if the environmental impact of the external sector is relatively low with respect to that of local activities. Otherwise, an unexpected scenario characterized by a reduction in domestic capital accumulation and the impoverishment of local agents can occur.     

The association of a lymphoreticular malignancy with an 11q deletion: A coincidence or a cancer susceptibility?

A balanced paternal chromosome insertion, ins(11) p14q14q21, resulted in a female with an unbalanced karyotype, del(11)(q14q21). This imbalance presumably arose from a meiotic crossover between the breakpoint of the insertion and the breakpoints of the deletion. This child developed a malignant lymphoma of the thymus in the first year of life. The association of a lymphoma with an 11q deletion may not be a coincidence in view of the frequent involvement of 11q in cytogenetic alterations of lymphomas.