Circadian oscillator proteins across the kingdoms of life : Structural aspects 06 Biological Sciences 0601 Biochemistry and Cell Biology

Circadian oscillators are networks of biochemical feedback loops that generate 24-hour rhythms and control numerous biological processes in a range of organisms. These periodic rhythms are the result of a complex interplay of interactions among clock components. These components are specific to the organism but share molecular mechanisms that are similar across kingdoms. The elucidation of clock mechanisms in different kingdoms has recently started to attain the level of structural interpretation. A full understanding of these molecular processes requires detailed knowledge, not only of the biochemical and biophysical properties of clock proteins and their interactions, but also the three-dimensional structure of clockwork components. Posttranslational modifications (such as phosphorylation) and protein-protein interactions, have become a central focus of recent research, in particular the complex interactions mediated by the phosphorylation of clock proteins and the formation of multimeric protein complexes that regulate clock genes at transcriptional and translational levels. The three-dimensional structures for the cyanobacterial clock components are well understood, and progress is underway to comprehend the mechanistic details. However, structural recognition of the eukaryotic clock has just begun. This review serves as a primer as the clock communities move towards the exciting realm of structural biology

The urban question in Harvey and Castells: Political economy vision and its constraints

Bu yazıda, kent sosyolojisinin en temel yöntem sorunsalı olan ‘kentin teorik bir nesne(obje) olarak’ kabul edilip edilemeyeceği konusu; Marksçı kentsel teorinin politik ekonomi vizyonunun yaklaşımları temelinde ele alınmaktadır. Marksçı kentsel teorinin içerisinde çeşitli varyantlar bulunmakla beraber, politik ekonomi vizyonu olarak adlandırılan yaklaşımın, bu teorinin genel eğilimlerini yansıtabilme noktasında yalnızca bir “ideal tip” oluşturduğu belirtilmelidir. Politik ekonomi vizyonunun temsilcileri olan Harvey ve Castells’in klasik çalışmalarında ise kent, teorik bir öneme sahip değildir. Kendisini kuşatan sosyal süreçlere bağlı olumsal(contingent) bir değişkendir. Bu yazıda, Harvey ve Castells’in kente yaklaşımları ele alınarak teorik kısıtları gösterilmeye çalışılmakta ve Marksçı yöntem için söz konusu edilen kısıtların Weberci yöntemle aşılabileceği ileri sürülmektedir.This article deals with the most essential methodological issue of the urban sociology, i.e. the question whether "the urban can be considered as a theoretical object or not", based on the approaches of political economy vision of the Marxist urban theory. While there are various variants in Marxist urban theory, it should be pointed out that the approach referred to as political economy vision constitutes only an "ideal type" in reflecting the general tendency of this theory. The classical studies of Harvey and Castells, being the representatives of political economy vision, do not attribute a theoretical importance on 'urban'. It is rather considered as a contingent variable depending upon surrounding social processes. This article discusses the urban approaches of Harvey and Castells with an effort to reveal their theoretical constraints, and puts forward that the constraints applying to Marxist methodology can be overcome by Weber's methodology

The "selfish brain" hypothesis for metabolic abnormalities in bipolar disorder and schizophrenia A hipótese do "cérebro egoísta" para alterações metabólicas no transtorno bipolar e na esquizofrenia

Metabolic abnormalities are frequent in patients with schizophrenia and bipolar disorder (BD), leading to a high prevalence of diabetes and metabolic syndrome in this population. Moreover, mortality rates among patients are higher than in the general population, especially due to cardiovascular diseases. Several neurobiological systems involved in energy metabolism have been shown to be altered in both illnesses; however, the cause of metabolic abnormalities and how they relate to schizophrenia and BD pathophysiology are still largely unknown. The "selfish brain" theory is a recent paradigm postulating that, in order to maintain its own energy supply stable, the brain modulates energy metabolism in the periphery by regulation of both allocation and intake of nutrients. We hypothesize that the metabolic alterations observed in these disorders are a result of an inefficient regulation of the brain energy supply and its compensatory mechanisms. The selfish brain theory can also expand our understanding of stress adaptation and neuroprogression in schizophrenia and BD, and, overall, can have important clinical implications for both illnesses.<br>Alterações metabólicas são frequentes em pacientes com esquizofrenia e transtorno bipolar (TB), levando a uma alta prevalência de diabetes e síndrome metabólica nessa população. Além disso, as taxas de mortalidade entre pacientes são mais altas do que na população geral, especialmente em decorrência de doenças cardiovasculares. Vários sistemas neurobiológicos envolvidos no metabolismo energético têm demonstrado alterações nas duas doenças; no entanto, a causa das alterações metabólicas e a forma como elas se relacionam com a fisiopatologia da esquizofrenia e do TB ainda são arenas em grande parte desconhecidas. A teoria do "cérebro egoísta" é um paradigma recente que postula que, para manter estável seu próprio fornecimento de energia, o cérebro modula o metabolismo da energia na periferia regulando tanto a alocação quanto a ingestão de nutrientes. Apresentamos neste artigo a hipótese de que as alterações metabólicas observadas nesses transtornos são resultado de uma regulação ineficiente do fornecimento de energia do cérebro e seus mecanismos compensatórios. A teoria do cérebro egoísta também pode expandir nosso entendimento sobre a adaptação ao estresse e a neuroprogressão na esquizofrenia e no TB, e, acima de tudo, pode ter implicações clínicas importantes para as duas doenças