Geometry shapes evolution of early multicellularity

Organisms have increased in complexity through a series of major evolutionary transitions, in which formerly autonomous entities become parts of a novel higher-level entity. One intriguing feature of the higher-level entity after some major transitions is a division of reproductive labor among its lower-level units. Although it can have clear benefits once established, it is unknown how such reproductive division of labor originates. We consider a recent evolution experiment on the yeast Saccharomyces cerevisiae as a unique platform to address the issue of reproductive differentiation during an evolutionary transition in individuality. In the experiment, independent yeast lineages evolved a multicellular "snowflake-like'' cluster form in response to gravity selection. Shortly after the evolution of clusters, the yeast evolved higher rates of cell death. While cell death enables clusters to split apart and form new groups, it also reduces their performance in the face of gravity selection. To understand the selective value of increased cell death, we create a mathematical model of the cellular arrangement within snowflake yeast clusters. The model reveals that the mechanism of cell death and the geometry of the snowflake interact in complex, evolutionarily important ways. We find that the organization of snowflake yeast imposes powerful limitations on the available space for new cell growth. By dying more frequently, cells in clusters avoid encountering space limitations, and, paradoxically, reach higher numbers. In addition, selection for particular group sizes can explain the increased rate of apoptosis both in terms of total cell number and total numbers of collectives. Thus, by considering the geometry of a primitive multicellular organism we can gain insight into the initial emergence of reproductive division of labor during an evolutionary transition in individuality.Comment: 7 figure

Experimental evolution of an alternating uni- and multicellular life cycle in Chlamydomonas reinhardtii

The transition to multicellularity enabled the evolution of large, complex organisms, but early steps in this transition remain poorly understood. Here we show that multicellular complexity, including development from a single cell, can evolve rapidly in a unicellular organism that has never had a multicellular ancestor. We subject the alga Chlamydomonas reinhardtii to conditions that favour multicellularity, resulting in the evolution of a multicellular life cycle in which clusters reproduce via motile unicellular propagules. While a single-cell genetic bottleneck during ontogeny is widely regarded as an adaptation to limit among-cell conflict, its appearance very early in this transition suggests that it did not evolve for this purpose. Instead, we find that unicellular propagules are adaptive even in the absence of intercellular conflict, maximizing cluster-level fecundity. These results demonstrate that the unicellular bottleneck, a trait essential for evolving multicellular complexity, can arise rapidly via co-option of the ancestral unicellular form. © 2013 Macmillan Publishers Limited. All rights reserved

Level and source of supplemental selenium for beef steers

Selenium (Se) is deficient in many Arkansas soils; therefore, an experiment was conducted on steers to evaluate the effects of two supplemental Se sources on performance, blood metabolites, and immune function. Thirty Angus-crossbred steers were blocked by weight and assigned within block to one of 15 pens (two steers/pen). Pens were assigned randomly within blocks to one of three dietary treatments consisting of a corn-soybean meal supplement devoid of supplemental Se (negative control, NC) or corn-soybean meal supplements providing 1.7 mg supplemental Se/d as sodium selenite (inorganic Se, ISe) or as Se yeast (organic Se, OSe). Steers were offered fescue hay to allow for approximately 10% refusals, and 1.1 kg/d (as fed basis) of the appropriate grain supplement. Level and source of supplemental Se did not affect average daily gain for the 105-d trial. By d 42, steers fed both sources of supplemental Se had greater blood Se concentrations than those fed the NC. On d 63 and 84, blood Se concentrations differed among all dietary treatments (NC \u3c ISe \u3c OSe), and on d 105 steers fed both sources of supplemental Se had greater blood Se concentrations than NC. Antibody response to vaccination for bovine respiratory viruses, or in vitro lymphocyte blastogenesis did not differ among steers fed the different diets. Both sources of supplemental Se increased blood Se concentrations, the organic source more rapidly than the inorganic source; however, Se level and source had minimal effects on immune function of weaned beef steers

Music Therapy for Patients Who Have Undergone Hematopoietic Stem Cell Transplant

Objectives. This study examines the short- and long-term QOL benefits of a music therapy intervention for patients recovering from hematopoietic stem cell transplantation (HSCT). Methods. Ninety allogeneic HSCT patients, after transplant, were randomized to receive ISO-principle (i.e., mood matching) based music therapy (MT; n = 29), unstructured music (UM; n = 30), or usual care (UC; n = 31) for four weeks. The ISO principle posits that patients may shift their mood from one state to another by listening to music that is equal to the individual\u27s initial mood state and subsequently listening to music selections that gradually shift in tempo and mood to match the patient\u27s desired disposition. Participants in MT and UM groups developed two audio CDs to help them feel more relaxed and energized and were instructed to use the CDs to improve their mood as needed. Short-term effects on mood and long-term effects on QOL were examined. Results. MT and UM participants reported improved mood immediately after listening to CDs; the within-group effect was greater for UM participants compared to MT participants. Participant group was not associated with long-term QOL outcomes. Conclusions. Music listening improves mood acutely but was not associated with long-term benefits in this study

Music Therapy for Patients Who Have Undergone Hematopoietic Stem Cell Transplant

Objectives. This study examines the short- and long-term QOL benefits of a music therapy intervention for patients recovering from hematopoietic stem cell transplantation (HSCT). Methods. Ninety allogeneic HSCT patients, after transplant, were randomized to receive ISO-principle (i.e., mood matching) based music therapy (MT; n = 29), unstructured music (UM; n = 30), or usual care (UC; n = 31) for four weeks. The ISO principle posits that patients may shift their mood from one state to another by listening to music that is equal to the individual\u27s initial mood state and subsequently listening to music selections that gradually shift in tempo and mood to match the patient\u27s desired disposition. Participants in MT and UM groups developed two audio CDs to help them feel more relaxed and energized and were instructed to use the CDs to improve their mood as needed. Short-term effects on mood and long-term effects on QOL were examined. Results. MT and UM participants reported improved mood immediately after listening to CDs; the within-group effect was greater for UM participants compared to MT participants. Participant group was not associated with long-term QOL outcomes. Conclusions. Music listening improves mood acutely but was not associated with long-term benefits in this study

Observing Rapport-Based Interpersonal Techniques (ORBIT) To Generate Useful Information From Child Sexual Abuse Suspects

In the United Kingdom alone, it is estimated that between 550,000 - 850,000 individuals pose varying degrees of sexual risk to children (with a central estimate of 700,000; National Crime Agency, 2021). Whilst the interview process is central to information gathering, empirical research focusing on child sexual abuse (CSA) suspect interviewing is limited. The present study analyses 45 hours of interviews with CSA suspects using the Observing Rapport-Based Interpersonal Techniques (ORBIT) framework. Originally used to code interviews with terrorist suspects (see Alison et al., 2013), this is the first application of ORBIT to another offender population. The ORBIT framework consists of three elements: (i) Motivational Interviewing skills (MI; Miller & Rollnick, 2009) include autonomy, acceptance, adaptation, empathy, and evocation; and (ii) the Interpersonal Behaviour Circle (IBC; Leary, 1955) measures interviewer and suspect interactions along two orthogonal dimensions (control-capitulate and confront-cooperate). Each IBC quadrant has adaptive (promoting conversation) and maladaptive (hampering communication) facets. The third element of ORBIT is an outcome measure of information that is of evidential significance or intelligence value – the ‘interview yield’. Multilevel structural equation modelling revealed interviewer adaptive/maladaptive behaviours had a direct impact on suspect adaptive/maladaptive behaviours respectively which, in turn, were associated with interview yield. Further, MI was associated with decreased suspect maladaptive (though not increased adaptive) behaviours. The study provides further support for the ORBIT research from Alison et al. (2013) in a new criminal population. It highlights that interviewers who adopt a rapport- based and interpersonally skilled approach will have information-gathering success with CSA suspects

Inhibition of Both HIV-1 Reverse Transcription and Gene Expression by a Cyclic Peptide that Binds the Tat-Transactivating Response Element (TAR) RNA

The RNA response element TAR plays a critical role in HIV replication by providing a binding site for the recruitment of the viral transactivator protein Tat. Using a structure-guided approach, we have developed a series of conformationally-constrained cyclic peptides that act as structural mimics of the Tat RNA binding region and block Tat-TAR interactions at nanomolar concentrations in vitro. Here we show that these compounds block Tat-dependent transcription in cell-free systems and in cell-based reporter assays. The compounds are also cell permeable, have low toxicity, and inhibit replication of diverse HIV-1 strains, including both CXCR4-tropic and CCR5-tropic primary HIV-1 isolates of the divergent subtypes A, B, C, D and CRF01_AE. In human peripheral blood mononuclear cells, the cyclic peptidomimetic L50 exhibited an IC50 ∼250 nM. Surprisingly, inhibition of LTR-driven HIV-1 transcription could not account for the full antiviral activity. Timed drug-addition experiments revealed that L-50 has a bi-phasic inhibition curve with the first phase occurring after HIV-1 entry into the host cell and during the initiation of HIV-1 reverse transcription. The second phase coincides with inhibition of HIV-1 transcription. Reconstituted reverse transcription assays confirm that HIV-1 (−) strand strong stop DNA synthesis is blocked by L50-TAR RNA interactions in-vitro. These findings are consistent with genetic evidence that TAR plays critical roles both during reverse transcription and during HIV gene expression. Our results suggest that antiviral drugs targeting TAR RNA might be highly effective due to a dual inhibitory mechanism

Modeling violations of the race model inequality in bimodal paradigms: co-activation from decision and non-decision components

The redundant-signals paradigm (RSP) is designed to investigate response behavior in perceptual tasks in which response-relevant targets are defined by either one or two features, or modalities. The common finding is that responses are speeded for redundantly compared to singly defined targets. This redundant-signals effect (RSE) can be accounted for by race models if the response times do not violate the race model inequality (RMI). When there are violations of the RMI, race models are effectively excluded as a viable account of the RSE. The common alternative is provided by co-activation accounts, which assume that redundant target signals are integrated at some processing stage. However, “co-activation” has mostly been only indirectly inferred and the accounts have only rarely been explicitly modeled; if they were modeled, the RSE has typically been assumed to have a decisional locus. Yet, there are also indications in the literature that the RSE might originate, at least in part, at a non-decisional or motor stage. In the present study, using a distribution analysis of sequential-sampling models (ex-Wald and Ratcliff Diffusion model), the locus of the RSE was investigated for two bimodal (audio-visual) detection tasks that strongly violated the RMI, indicative of substantial co-activation. Three model variants assuming different loci of the RSE were fitted to the quantile reaction time proportions: a decision, a non-decision, and a combined variant both to vincentized group as well as individual data. The results suggest that for the two bimodal detection tasks, co-activation has a shared decisional and non-decisional locus. These findings point to the possibility that the mechanisms underlying the RSE depend on the specifics (task, stimulus, conditions, etc.) of the experimental paradigm