Biological Prescience: The Role of Anticipation in Organismal Processes

Anticipation is the act of using information about the past and present to make predictions about future scenarios. As a concept, it is predominantly associated with the psychology of the human mind; however, there is accumulating evidence that diverse taxa without complex neural systems, and even biochemical networks themselves, can respond to perceived future conditions. Although anticipatory processes, such as circadian rhythms, stress priming, and cephalic responses, have been extensively studied over the last three centuries, newer research on anticipatory genetic networks in microbial species shows that anticipatory processes are widespread, evolutionarily old, and not simply reserved for neurological complex organisms. Overall, data suggest that anticipatory responses represent a unique type of biological processes that can be distinguished based on their organizational properties and mechanisms. Unfortunately, an empirically based biologically explicit framework for describing anticipatory processes does not currently exist. This review attempts to fill this void by discussing the existing examples of anticipatory processes in non-cognitive organisms, providing potential criteria for defining anticipatory processes, as well as their putative mechanisms, and drawing attention to the often-overlooked role of anticipation in the evolution of physiological systems. Ultimately, a case is made for incorporating an anticipatory framework into the existing physiological paradigm to advance our understanding of complex biological processes.

The Frailty Syndrome: An Emergent Property of Parallel Dysregulation in Multiple Physiological Systems?

Despite its widespread presence in older adults, frailty etiology is still unclear, being associated with dysregulation in diverse physiological systems. Here, we show evidence that frailty emerges from broad loss of homeostasis integrated through complex systems dynamics. Using the NuAge and WHAS cohorts, we calculated Mahalanobis distance-based physiological dysregulation in six systems and tested the breadth, diffuseness, and nonlinearity of associations between frailty and system-specific dysregulation. We found clear support for breadth of associations, but only partial support for diffuseness and nonlinearity: 1) physiological dysregulation is positively associated with frailty in many or all systems, depending on analyses; 2) the number of dysregulated systems or the total amount of dysregulation are more predictive than individual systems, but results only partially replicated across cohorts; 3) dysregulation trends are exponential, but not always significant. These results suggest, but do not fully prove, that frailty is an emergent property of complex systems dynamics.

The opto-respiratory compromise: Balancing oxygen supply and light transmittance in the retina

The light-absorbing retina has an exceptionally high oxygen demand, which imposes two conflicting needs: high rates of blood perfusion and an unobstructed light path devoid of blood vessels. This review discusses mechanisms and physiological tradeoffs underlying retinal oxygen supply in vertebrates and examines how these physiological systems supported the evolution of vision.

Prenatal Adversity Alters the Epigenetic Profile of the Prefrontal Cortex: Sexually Dimorphic Effects of Prenatal Alcohol Exposure and Food-Related Stress

Prenatal adversity or stress can have long-term consequences on developmental trajectories and health outcomes. Although the biological mechanisms underlying these effects are poorly understood, epigenetic modifications, such as DNA methylation, have the potential to link early-life environments to alterations in physiological systems, with long-term functional implications. We investigated the consequences of two prenatal insults, prenatal alcohol exposure (PAE) and food-related stress, on DNA methylation profiles of the rat brain during early development. As these insults can have sex-specific effects on biological outcomes, we analyzed epigenome-wide DNA methylation patterns in prefrontal cortex, a key brain region involved in cognition, executive function, and behavior, of both males and females. We found sex-dependent and sex-concordant influences of these insults on epigenetic patterns. These alterations occurred in genes and pathways related to brain development and immune function, suggesting that PAE and food-related stress may reprogram neurobiological/physiological systems partly through central epigenetic changes, and may do so in a sex-dependent manner. Such epigenetic changes may reflect the sex-specific effects of prenatal insults on long-term functional and health outcomes and have important implications for understanding possible mechanisms underlying fetal alcohol spectrum disorder and other neurodevelopmental disorders.

Dying

What actually happens when someone dies? Are there signs that death is approaching? Physicians sometimes notice what is called a terminal drop in basic physiological systems that seems to presage death, but those signs do not occur in every case. In the “twilight of death,” not every cell in the body dies at the same rate. However, once death occurs, the signs are more clear and involve a loss of respiration and heartbeat, rigor mortis, and the pooling of blood, among other things. Some people report near-death experiences, and one might wonder if those provide a glimpse of the afterlife. Yet most of the features of near-death experiences can be explained physiologically. Consciousness and its relationship to the physical brain remain to be understood.

The Role of the Gastric Hormones Ghrelin and Nesfatin-1 in Reproduction

Ghrelin and nesfatin-1 are enteroendocrine peptide hormones expressed in rat X/A-like and human P/D1cells of the gastric mucosa. Besides their effect on food intake, both peptides are also implicated in various other physiological systems. One of these is the reproductive system. This present review illustrates the distribution of ghrelin and nesfatin-1 along the hypothalamus–pituitary–gonadal (HPG) axis, their modulation by reproductive hormones, and effects on reproductive functions as well as highlighting gaps in current knowledge to foster further research.

Micro-Physiological-Systems enable investigation of hypoxia induced pathological processes in human aortic valve cells and tissues

Aortic valve (AV) stenosis is characterized by tissue fibrosis and calcification. Fibrous thickening can result in reduced tissue oxygen supply leading to pathological valvular interstitial cell (VIC) differentiation and calcification. Static 2D VIC cultures and animal models are limited in the ability to reflect human AV calcification. Culturing of VICs in micro-physiological-systems (MPS) in a pulsatile flow and the establishment of a modular AV tissue incubation chamber (TIC) are new approaches to evaluate pathophysiological processes of AV disease. Therefore, a MPS able to adjust hypoxic conditions was applied for VIC culture. A significant increase of mRNA-expression of EGLN1 and HIF1α- regulated LDHA and HIF1α nuclear localisation were proven under hypoxia. AV tissue culture was established within a TIC and viability was monitored by Resazurin-reduction in the incubation medium and visualized by LDH-activity in tissue cryosections. Viability was compared between fluid and static incubated tissues revealing an advantageous effect of the fluidic assay condition. Consecutively, the application of MPS in AV research allows i) the investigation of VIC cultures with efficient oxygen regulation and ii) the culture of porcine or human AV tissues preserving viability and specifically reflecting in vivo parameters. These methods open up new possibilities beyond static 2D culture and facilitate a reduction of animal experiments in AV research.