All practices are shared, but some more than others: Sharedness of social practices and time-use in food consumption

Even though we spend less and less time cooking and eating, food consumption remains a corner stone of the temporal organisation of everyday life. This paper is interested in how and to which extent food practices can be described as shared. We situate our investigation at the confluence of practice theories and the empirical analysis of time-use surveys. While qualitative research highlights the interrelations between many activities and agents necessary to consume food, quantitative data, such as time-use surveys, underscore the shared temporality of eating. We ask whether practices are shared beyond being socially recognised and mutually understandable forms of actions. Accordingly, we are interested in how some practices might be described as more shared than others, or shared in different ways? We identify three characteristics of sharedness: participation, commitment and temporal concentration. The latter is a key indicator of dispersed collective activity, inasmuch as participants engage in the practice in similar ways even without coordinating explicitly around it. We measure and compare the characteristics of sharedness by analysing the Dutch time-use survey 2011 (N = 2,005). Such an analysis offers empirical evidence for our characterisation of sharedness by mapping five food-related practices (eating a meal, snacking, cooking, shopping, and cleaning) onto five dimensions of temporality (duration, sequence, periodicity, synchronisation, and tempo). The characteristics of sharedness afford a systematic framework to analyse culture in dispersed collective activity. Our analysis also provides novel vistas to reflect upon power in shared practices by investigating their temporal concentration.

DNA information: from digital code to analogue structure

The digital linear coding carried by the base pairs in the DNA double helix is now known to have an important component that acts by altering, along its length, the natural shape and stiffness of the molecule. In this way, one region of DNA is structurally distinguished from another, constituting an additional form of encoded information manifest in three-dimensional space. These shape and stiffness variations help in guiding and facilitating the DNA during its three-dimensional spatial interactions. Such interactions with itself allow communication between genes and enhanced wrapping and histone–octamer binding within the nucleosome core particle. Meanwhile, interactions with proteins can have a reduced entropic binding penalty owing to advantageous sequence-dependent bending anisotropy. Sequence periodicity within the DNA, giving a corresponding structural periodicity of shape and stiffness, also influences the supercoiling of the molecule, which, in turn, plays an important facilitating role. In effect, the super-helical density acts as an analogue regulatory mode in contrast to the more commonly acknowledged purely digital mode. Many of these ideas are still poorly understood, and represent a fundamental and outstanding biological question. This review gives an overview of very recent developments, and hopefully identifies promising future lines of enquiry.

Comparative Analysis of Sequence Periodicity among Prokaryotic Genomes Points to Differences in Nucleoid Structure and a Relationship to Gene Expression

ABSTRACT Regular spacing of short runs of A or T nucleotides in DNA sequences with a period close to the helical period of the DNA double helix has been associated with intrinsic DNA bending and nucleosome positioning in eukaryotes. Analogous periodic signals were also observed in prokaryotic genomes. While the exact role of this periodicity in prokaryotes is not known, it has been proposed to facilitate the DNA packaging in the prokaryotic nucleoid and/or to promote negative or positive supercoiling. We developed a methodology for assessments of intragenomic heterogeneity of these periodic patterns and applied it in analysis of 1,025 prokaryotic chromosomes. This technique allows more detailed analysis of sequence periodicity than previous methods where sequence periodicity was assessed in an integral form across the whole chromosome. We found that most genomes have the periodic signal confined to several chromosomal segments while most of the chromosome lacks a strong sequence periodicity. Moreover, there are significant differences among different prokaryotes in both the intensity and persistency of sequence periodicity related to DNA curvature. We proffer that the prokaryotic nucleoid consists of relatively rigid sections stabilized by short intrinsically bent DNA segments and characterized by locally strong periodic patterns alternating with regions featuring a weak periodic signal, which presumably permits higher structural flexibility. This model applies to most bacteria and archaea. In genomes with an exceptionally persistent periodic signal, highly expressed genes tend to concentrate in aperiodic sections, suggesting that structural heterogeneity of the nucleoid is related to local differences in transcriptional activity.