A universal mechanism of biomass density homeostasis via ribosomal counterions

In all growing cells, the cell envelope must expand in concert with cytoplasmic biomass to prevent lysis or molecular crowding. The complex cell wall of microbes and plants makes this challenge especially daunting and it unclear how cells achieve this coordination. Here, we uncover a striking linear increase of cytoplasmic pressure with growth rate in E. coli. Remarkably, despite this increase in turgor pressure with growth rate, cellular biomass density was constant across a wide range of growth rates. In contrast, perturbing pressure away from this scaling directly affected biomass density. A mathematical model, in which endopeptidase-mediated cell wall fluidization enables turgor pressure to set the pace of cellular volume expansion, not only explains these confounding observations, but makes several surprising quantitative predictions that we validated experimentally. The picture that emerges is that changes in turgor pressure across growth rates are mediated by counterions of ribosomal RNA. Profoundly, the coupling between rRNA and cytoplasmic pressure simultaneously coordinates cell wall expansion across growth rates and exerts homeostatic feedback control on biomass density. Because ribosome content universally scales with growth rate in fast growing cells, this universal mechanism may control cell wall biosynthesis in microbes and plants and drive the expansion of ribosome-addicted tumors that can exert substantial mechanical forces on their environment.

Glycolysis/gluconeogenesis specialization in microbes is driven by biochemical constraints of flux sensing

Central carbon metabolism is highly conserved across microbial species, but can catalyze very different pathways depending on the organism and their ecological niche. Here, we study the dynamic reorganization of central metabolism after switches between the two major opposing pathway configurations of central carbon metabolism, glycolysis, and gluconeogenesis in Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas putida. We combined growth dynamics and dynamic changes in intracellular metabolite levels with a coarse-grained model that integrates fluxes, regulation, protein synthesis, and growth and uncovered fundamental limitations of the regulatory network: After nutrient shifts, metabolite concentrations collapse to their equilibrium, rendering the cell unable to sense which direction the flux is supposed to flow through the metabolic network. The cell can partially alleviate this by picking a preferred direction of regulation at the expense of increasing lag times in the opposite direction. Moreover, decreasing both lag times simultaneously comes at the cost of reduced growth rate or higher futile cycling between metabolic enzymes. These three trade-offs can explain why microorganisms specialize for either glycolytic or gluconeogenic substrates and can help elucidate the complex growth patterns exhibited by different microbial species.

Stereoselective organocatalyzed glycosylations - thiouracil, thioureas and monothiophthalimide act as Brønsted acid catalysts at low loadings

Thiouracil catalyzes stereoselective glycosylations with galactals in loadings as low as 0.1 mol%. It is proposed that in these glycosylations thiouracil, monothiophthalimide, and the previously reported catalyst, Schreiner's thiourea, do not operate via a double H-bonding mechanism but rather by Brønsted acid/base catalysis. In addition to the synthesis of 2-deoxyglycosides and glycoconjugates, we report the first organocatalytic synthesis of 1,1'-linked trehalose-type sugars.

You see me, but do you hear me? The science and sensibility of trans-species dialogue

Talking with animals comes naturally and happens the world over. Traditional indigenous peoples depend on their abilities to understand the birds, grazers, and hunters who share their land and waters and we converse intimately with the dogs, cats, birds, and other animals with whom we live. Nonetheless, science and society cast a skeptical eye on claims that animals think and communicate on par with humans. Now, this view is changing. We have entered into a remarkable new ethical and psychological consilience as scientific theories and data converge with age-old experience. Communicating with animals — hearing what they are saying and talking with them — is not only possible, it has never stopped.

Developmental context effects on bicultural posttrauma self repair in chimpanzees

Longitudinal studies have shown how early developmental contexts contribute significantly to self-development; their influence extends through adulthood, informs sociality, and affects resilience under severe stress. While the importance of sociality in trauma recovery is recognized, the relationship between developmental and posttrauma contexts and recovery effects is less appreciated, particularly in cases in which recovery contexts differ widely from the culture of origin. Using an attachment-based model of bicultural (competence in two cultures) development, the authors examined the role of self in posttrauma repair of chimpanzees (Pan troglodytes) who had been differentially reared by humans during neuroethologically formative periods and subsequently used as biomedical subjects. Results show that variations in posttrauma schema correlate with early socialization patterns. Self-resilience supports, but also may constrain, recovery depending on the compatibility of internal self models with recovery resources. Trauma severity notwithstanding, the cultural context of origin emerges as a critical factor in designing effective therapeutic intervention and assessments in primates, humans inclusive. Finally, the results underscore the ethical implications for the practices of cross-fostering nonhuman primates and their use in research.

Building an inner sanctuary: complex PTSD in chimpanzees

Through the analysis of case studies of chimpanzees (Pan troglodytes troglodytes) in residence at a sanctuary, who previously sustained prolonged captivity and biomedical experimentation, we illustrate how human psychological models of diagnosis and treatment might be approached in great apes. This study reflects growing attention to ethical, scientific, and practical problems associated with psychological well-being of animals. The analysis concludes that a diagnosis of Complex PTSD in chimpanzees is consistent with descriptions of trauma-induced symptoms as described by the DSM-IV and human trauma research. We discuss how these findings relate to diagnosis and treatment of chimpanzees in captivity and the issue of their continued laboratory use. This clinical study contributes toward theory and therapeutic practices of an emergent trans-species psychology inclusive of both humans and other species. Such an ability to extend what we know about models of human trauma opens deeper understanding and insights into ourselves as well as individuals from other species.

Avian neuroanatomy revisited: from clinical principles to avian cognition

Several significant advances in understanding brain-behavior development have made a critical contribution to clinical assessment of companion birds. First, psychobiological health and its dysfunctions now are understood as the product of nature and nurture and therefore exquisitely sensitive to stressors effected by altered socio-ecological conditions within and across generations. Second, discoveries associated with avian brain evolution and ethology show that emotional and cognitive capacities of birds are comparable to mammals. This article presents an overview of these new perspectives and, following, discusses specific, clinically relevant anatomy of the avian central nervous system. By understanding the location of these tracts and their function and the location of the cranial nerves and their nuclei in the brain stem, the clinician can understand and perform the neurological examination, better interpret findings, and localize lesions.

Detecting climate-induced patterns using wavelet analysis

One of the difficulties encountered in the detection of ecosystem responses to climate change is distinguishing climate-induced patterns from those created by other sources. For example, changes in the trend of stream discharge records over time may reflect a composite response of changes in the climate (i.e. precipitation and temperature), land-use (e.g. timber harvesting and grazing), and local basin characteristics. Methods which quantify and relate information of temporal and spatial patterns across scales are critical to assess climatically induced changes in the forest and stream ecosystems. A methodology utilizing wavelet analysis is introduced for the purpose of identifying and isolating inferred climatic components of the hydrologic record. Trends observed in stream discharge records from eastern Oregon, USA are identified and used to illustrate the utility of a new time series technique, wavelet analysis, as a complementary approach for discerning pattern. This methodology affords an informed procedure for choosing filter dimensions for the purpose of signal decomposition. The wavelet cross-covariance is applied to precipitation and discharge records to identify the climatic component in the discharge record. Reconstruction of these dominant frequencies is effected to isolate the climatic components. The discharge pattern shows two dominant scales of pattern coincident with the precipitation record. A 3-year half-period pattern is found to be correlated with the Southern Oscillation Index at the same frequency.