Kolmogorov complexity of epithelial pattern formation: The role of regulatory network configuration

The tissues of multicellular organisms are made of differentiated cells arranged in organized patterns. This organization emerges during development from the coupling of dynamic intra- and intercellular regulatory networks. This work applies the methods of information theory to understand how regulatory network structure both within and between cells relates to the complexity of spatial patterns that emerge as a consequence of network operation. A computational study was performed in which undifferentiated cells were arranged in a two dimensional lattice, with gene expression in each cell regulated by identical intracellular randomly generated Boolean networks. Cell–cell contact signalling between embryonic cells is modeled as coupling among intracellular networks so that gene expression in one cell can influence the expression of genes in adjacent cells. In this system, the initially identical cells differentiate and form patterns of different cell types. The complexity of network structure, temporal dynamics and spatial organization is quantified through the Kolmogorov-based measures of normalized compression distance and set complexity. Results over sets of random networks that operate in the ordered, critical and chaotic domains demonstrate that: (1) ordered and critical networks tend to create the most information-rich patterns; (2) signalling configurations in which cell-to-cell communication is non-directional mostly produce simple patterns irrespective of the internal network domain; and (3) directional signalling configurations, similar to those that function in planar cell polarity, produce the most complex patterns, but only when the intracellular networks function in non-chaotic domains.     

Interactions between species and environments from incomplete information

There are two contradictory aspects of the adaptive process in evolution. The first is that species must optimally increase their own fitness in a given environment. The second is that species must maintain their variation to be ready to respond to changing environments. In a strict sense, these two aspects might consider to be mutually exclusive. If species are optimally adapted, then the variation in the species that is suboptimal decreases and vice versa. To resolve this dilemma, species must find a balance between optimal adaptation and robust adaptation. Finding the balance between these processes requires both the local and global complete, static information. However, the balance between the processes must be dynamic. In this study, we propose a model that illustrates dynamic negotiation between the global and local information using lattice theory. The dynamic negotiation between these two levels results in an overestimate of fitness for each species. The overestimation of fitness in our model represents the multiplicity of fitness which is sometimes discussed as the exaptation. We show that species in our model demonstrate the power law of the lifespan distribution and 1/f fluctuation for the adaptive process. Our model allows for a balance between optimal adaptation and robust adaptation without any arbitrary parameters.     

雄性黄山短尾猴(Macaca thibetana)攻击支持雌性以换取交配回报

生物市场理论认为动物个体之间通过某种协定交换有价值的商品,使双方均受益。该研究采用目标动物法、行为取样法和连续记录法,对浮溪黄山野生猴谷鱼鳞坑短尾猴(Macaca thibetana)A1群(YA1群)和A2群(YA2群)成年个体在非繁殖季节(2011年8月—12月)和繁殖季节(2012年2月—5月)的雄性攻击支持雌性行为和交配行为进行研究,探讨雄性攻击支持雌性与交配之间的关系。两猴群在繁殖季节和非繁殖季节雄性攻击支持雌性与交配行为均呈显著正相关;YA2群繁殖季节与非繁殖季节攻击支持后交配频次均显著高于随机交配;YA1群在繁殖季节攻击支持后交配频次与随机交配频次差异不显著,但在非繁殖季节攻击支持后交配频次显著高于随机交配,说明短尾猴成年雄性攻击支持雌性可以换取与该雌性个体的交配回报。本研究验证了生物市场理论中社会行为存在交换,首次证明了雄性攻击支持可以换取雌性的交配回报,为进一步研究雄性性竞争与雌性选择提供了实例。     

Cross-country variation in interracial marriage: a USA–Canada comparison of metropolitan areas

While black–white intermarriage is uncommon in the USA, blacks in Canada are just as likely to marry whites as to marry blacks. Asians, in contrast, are more likely to marry whites in the USA than in Canada. We test the claim that high rates of interracial marriage are indicative of high levels of social integration against Peter Blau's ‘macrostructural’ thesis that relative group size is the key to explaining differences in intermarriage rates across marriage markets. Using micro-data drawn from the American Community Survey and the Canadian census, we demonstrate that the relative size of racial groups accounts for over two-thirds of the USA–Canada difference in black–white unions and largely explains the cross-country difference in Asian–white unions. Under broadly similar social and economic conditions, a large enough difference in relative group size can become the predominant determinant of group differences in the prevalence of interracial unions.     

Racial regimes,comparative politics,and the problem of judgment

This review essay examines the practice of judgment that characterized the subfield of comparative politics from its origins in openly racist ideas of the capacity for self-rule through to its twentieth-century behavioralist and positivist iterations. Though continually faced with new political phenomena that called into question its inherited criteria of judgment, comparative politics tended to practice determinative rather than reflective judgment, that is, to subsume the particulars of other cultures under known rules. Further, the essay examines the racialized conception of self-rule described by Michael Hanchard as embedded in a larger problem of Western political thinking: the flight from action into rule and tendency to think of politics wholly in terms of ruling and being ruled.     

A white side of black Britain: The concept of racial literacy

Opposition to transracial adoption on both sides of the Atlantic, has been based, in part, on the assumption that white parents cannot understand race or racism and thus cannot properly prepare children of multiracial heritage to cope with racism. In this article I draw on a seven-year ethnographic study to offer an intensive case study of white transracial birth parents that counters this racial logic. I draw on a subset of data collected from field research and in-depth interviews with 102 members of black-white interracial families in England. I provide an analysis of three practices that I discovered among white transracial birth parents who were attempting to cultivate ‘black’ identities in their children of multiracial heritage. I offer the concept of ‘racial literacy’ to theorize their parental labour as a type of anti-racist project that remains under the radar of conventional sociological analyses of racism and anti-racist social movements.     

Enzymatic Synthesis of the Crithidia Factors in Cell-free Extracts of Serratia indica

The concomitant production of formic acid and pterin compounds from guanosine-5′-triphosphate (GTP) has been found in cell-free extracts of Serratia indica. Among the pterin compounds, l-threo-neopterin–the major Crithidia factor in S. indica–, a cyclic phosphate of neopterin (cNP), d-erythro-neopterin and 6-hydroxymethyl pterin were detected and isolated. Formate-¹⁴C elimination from GTP-8-¹⁴C was quantitatively distributed in the ethyl acetate layer in the ehyl acetate-hydrochloric acid partition system. Carbon 8 of GTP was released as formic acid. Enzymatic production of formate and cNP was linear for 2 hr at 37°C. Formate production was proportional to the enzyme concentration. The optimum pH for formate elimination was observed around pH 8.6. Optimum temperature for the production of formate and cNP was 50°C. The apparent Km value of GTP for formate production was 6.2×10^?bm. Formate eliminating activity was activated by disodium phosphate but was inhibited by Mg²⁺ or AMP. Incorporation of GTP-U-¹⁴C into pterin compounds was also regulated with disodium phosphate. Effective incorporation into cNP and d-erythro-neopterin occurred in the presence of phosphate. When phosphate was omitted from the system, however, effective incorporation into 6-hydroxymethyl pterin was observed. The biosynthetic process of the Crithidia factors, i.e. l-threo-neopterin and cNP, from GTP in S. indica is also discussed.     

Constant Pharmacologic Effect and Chronopharmacology: Theoretical Aspects

The theoretical drug infusion rates requisite to obtain a constant pharmacologic effect are determined taking into account chronopharmacologic phenomena. The introduction of chronopharmacology into pharmacokinetic theory leads to a clocktime-dependent infusion rate. The infusion modulation depends both on type of chronophenomenon, chronopharmacokinetics or chronestesy, and plasma clearance rate of the drug. In the presence of chronestesy of a biosystem the pharmacologic effect can be maintained constant only when plasma drug clearance is fast enough to allow an adequate modulation of the plasma drug concentration. Although the established equations proceed from theoretical concept they could be useful for programming drug delivery systems.