Sensitization of T cells to apoptosis—A role for ROS?

T cell homeostasis is achieved by balancing the production and proliferation of T cells with their apoptotic cell death. Activation of naïve T cells by antigen in the context of MHC results in the massive expansion of antigen-specific T cells and the production of reactive oxygen species (ROS). Following expansion, the majority of the T cells die via apoptosis, while a small number of them survive and differentiate into memory T cells. This cell fate decision is crucial to our understanding of how autoimmunity is avoided and how immunity is maintained. It has become increasingly clear that ROS can affect this cell fate decision by sensitizing T cells to apoptosis. Interestingly, ROS have effects on both intrinsic and extrinsic apoptosis pathways through modulation of expression of the major molecules in these pathways, Bcl-2 and FasL. In this review, we will focus on the pro-apoptotic effects of ROS and mechanisms by which they regulate the death of T cells.     

Strategies to select yeast starters cultures for production of flavor compounds in cachaça fermentations

In this work, we have used classical genetics techniques to find improved starter strains to produce cachaça with superior sensorial quality. Our strategy included the selection of yeast strains resistant to 5,5′,5″-trifluor-d,l-leucine (TLF) and cerulenin, since these strains produce higher levels of higher alcohols and esters than parental strains. However, no clear relationship was observed when levels of flavoring compounds were compared with the levels expression of the genes (BAT1, BAT2, ATF2, EEB1 genes) involved with the biosynthesis of flavoring compounds. Furthermore, we determined the stability of phenotypes considered as the best indicators of the quality of the cachaça for a parental strain and its segregants. By applying the principal component analysis, a cluster of segregants, showing a high number of characteristics similar to the parental strain, was recognized. One segregant, that was resistant to TLF and cerulenin, also showed growth stability after six consecutive replications on plates containing high concentrations of sugar and ethanol. “Cachaça” produced at laboratory scale using a parental strain and this segregant showed a higher level of flavoring compounds. Both strains predominated in an open fermentative process through seven cycles, as was shown by mitochondrial restriction fragment length polymorphisms analysis. Based on the physical chemical composition of the obtained products, the results demonstrate the usefulness of the developed strategies for the selection of yeast strains to be used as starters in “cachaça” production.     

Rehabilitating a biological notion of race? A response to Sesardic

The point Sesardic (Biol Philos 25: 143–162, 2010) makes about the possibility of distinguishing groups for which there is a lot of within-group variation is not sufficient to rehabilitate a biological concept of race. In this note, I sketch a number of issues that quickly arise once we delve more deeply into the relevant scientific knowledge, concepts, methods, and questions for inquiry.     

Adaptive doses of irradiation—an approach to a new therapy concept for bladder cancer?

Radiation adaptive response in terms of induced radioresistance or hyperradiosensitivity, has been studied in HCV29 (human bladder epithelium) and RT4 (human bladder carcinoma) cell lines. After pre-irradiation doses of 0.05 Gy or 0.1 Gy, HCV29 cells showed induced radioresistance, whereas after pre-irradiation doses of 0.05 Gy, 0.1 Gy, 0.2 Gy, and 0.5 Gy, the RT4 cells clearly showed hyperradiosensitivity. On the basis of these results, an approach has been developed that may lead to a concept for a new radiotherapeutic regimen of bladder cancer that includes protection of normal cells, on the one hand, and the potential of tumor cell damage, on the other hand. These findings need to be confirmed in further studies for the benefit of the patients.     

Spirula—a window to the embryonic development of ammonoids? Morphological and molecular indications for a palaeontological hypothesis

Nautilus is not suitable as a model organism to infer biological functions, embryonic development, or mode of life in ammonoids. A brief review of the available morphological data is given and molecular data are added to discuss the usefulness of Spirula as a biological proxy for ammonoids. Indeed, there are many morphological hints indicating that Spirula could be a useful model organism for approaching the embryonic development of ammonoids. The molecular data seem to support this hypothesis. However, a universal model character of Spirula cannot be detected as, e.g., the mode of feeding probably differs between Spirula and ammonoids.     

A mate to die for? A model of conditional monogyny in cannibalistic spiders

Monogynous males in various species actively limit themselves to mating with a single female in their lifetime. Whereas previous models have considered monogyny as an obligate mating strategy, here we explore the potential of monogyny to evolve as a context‐specific (conditional) behavior. Using a state‐dependent dynamic game model based on the biology of the cannibalistic spider Argiope bruennichi, we confirm that conditional monogyny can evolve under broad conditions, including an even sex ratio. We predict that males should make a terminal investment when mating with large, virgin females, especially if population density is low and the encounter occurs late in the season. We encourage empirical tests for the existence of conditional monogyny in all species where monogyny occurs in the absence of strict morphological constraints that would make it obligatory.     

What happens to dead birds left in a cave and its vicinity for a quarter of a century? A taphonomic experiment

Abstract

This paper describes a bird carcass-monitoring experiment carried out in a limestone cave and its immediate vicinity in southern Poland for almost a quarter of a century. Some specimens deposited outside the cave were preserved almost intact, others were only a little weathered. Soft tissues and remnants of feathers were preserved in some of the samples inside the cave. Stages of bone modifications that can occur in a cave have been distinguished and illustrated for the first time. Also, bird bones from owl pellets have been used in a carcass-monitoring experiment for the first time. Bone modifications in the form of wrinkling, bending and/or collapsing of the bone surface were recorded only on the bones of birds that decomposed inside the cave, and not on bones that had been isolated from owl pellets prior to their deposition in the cave. Therefore, it is postulated that avian – and possibly also small mammal – bones that have been defleshed, either by people or animals, have a greater chance to survive and fossilize than bones deposited as complete carcasses in a cave. This agrees with the generally accepted notion that larger assemblages of small vertebrates in caves are usually the result of predator accumulation.     

Hands-on or Video-based Learning with ANTicipation? A Comparative Approach to Identifying Student Motivation and Learning Enjoyment During a Lesson about Ants

The observation of living animals in school laboratories provides authentic views of biological research. Various studies stress the importance of primary experiences in biology classes. However, educational films may serve as an alternative in some cases. The aim of this study was to investigate student motivation before and after treatments, including (1) an educational film, (2) a hands-on activity with living animals accompanied by an educational film and (3) a hands-on activity with living animals. We investigated the influence of teaching method, gender and class level on student motivation and learning enjoyment. In all treatments, Temnothorax ants were addressed, which can be easily kept and observed. This paper is within the scope of a longitudinal project based on the concept of ‘ant research’ in class. Students (N = 140) from six classes (lower and intermediate secondary school levels) participated in the study. Student motivation was measured using a two-stage test design, including a standardised questionnaire on current motivation and a test on learning enjoyment. The findings of this study suggest that the younger students prefer hands-on activities, while students at an intermediate secondary school level are more interested in video-based learning. Since the combination of hands-on activity and video yielded the best results, the potential of using videos as facilitators for hands-on learning is discussed.     

Influenza A virus—a model for viral antigen presentation to cytotoxic T lymphocytes

Human influenza A virus is characterized by its high degree of variability and by its ability to cause frequent epidemics of disease. Most of the variation occurs in the two surface glycoproteins of the virus, against which protective antibodies are directed. In contrast, the strong MHC class I-restricted CTL response to infection with virus is predominantly specific for internal viral proteins which are relatively well conserved, and is cross-reactive between different strains of influenza A virus. However, the natural evolution of influenza viruses is largely driven by selection with antibody, with no firm evidence of selection by CTL. In normal individuals influenza virus produces an acute, localized infection, and this in part may reflect an inability to escape the CTL response.     

Heterotrophic Compensation: A Possible Mechanism for Resilience of Coral Reefs to Global Warming or a Sign of Prolonged Stress?

Thermally induced bleaching has caused a global decline in corals and the frequency of such bleaching events will increase. Thermal bleaching severely disrupts the trophic behaviour of the coral holobiont, reducing the photosynthetically derived energy available to the coral host. In the short term this reduction in energy transfer from endosymbiotic algae results in an energy deficit for the coral host. If the bleaching event is short-lived then the coral may survive this energy deficit by depleting its lipid reserves, or by increasing heterotrophic energy acquisition. We show for the first time that the coral animal is capable of increasing the amount of heterotrophic carbon incorporated into its tissues for almost a year following bleaching. This prolonged heterotrophic compensation could be a sign of resilience or prolonged stress. If the heterotrophic compensation is in fact an acclimatization response, then this physiological response could act as a buffer from future bleaching by providing sufficient heterotrophic energy to compensate for photoautotrophic energy losses during bleaching, and potentially minimizing the effect of subsequent elevated temperature stresses. However, if the elevated incorporation of zooplankton is a sign that the effects of bleaching continue to be stressful on the holobiont, even after 11 months of recovery, then this physiological response would indicate that complete coral recovery requires more than 11 months to achieve. If coral bleaching becomes an annual global phenomenon by mid-century, then present temporal refugia will not be sufficient to allow coral colonies to recover between bleaching events and coral reefs will become increasingly less resilient to future climate change. If, however, increasing their sequestration of zooplankton-derived nutrition into their tissues over prolonged periods of time is a compensating mechanism, the impacts of annual bleaching may be reduced. Thus, some coral species may be better equipped to face repeated bleaching stress than previously thought.     

Dealing with Lead in Hybrid Perovskite: A Challenge to Tackle for a Bright Future of This Technology?

Hybrid Perovskite (HP) semiconductors have been skyrocketing the field of new generation photovoltaics and expanding into advanced optoelectronics. Perovskite photovoltaics (PV) can give a tremendous push to the green energy transition, which calls for efficient, low cost, but also environmentally friendly solutions. Halide perovskites present a serious drawback related to the presence of toxic materials, i.e., lead, with its associated health and environment concerns. These concerns severely hamper their commercialization. So far, only a few viable alternatives to Pb have been found, which lag behind in terms of power conversion efficiency. Here, a forward‐looking perspective is developed presenting different potential strategies to overcome the environmental and health issues related to the use and release of lead for operative HP solar cells. The possible lead‐leakage paths and related “remediation” tools are reviewed, and possible strategies are collated with a view to beginning a new era of lead containing HP devices. Finally, through a comparison with existing lead‐based technology, a comparative study is presented to provide the tools that are essential for a real evaluation of the impact of lead content on HP commercialization.     

A system dynamics approach in LCA to account for temporal effects—a consequential energy LCI of car body-in-whites

Purpose  

The purpose of this paper is to take steps towards a life cycle assessment that is able to account for changes over time in resource flows and environmental impacts. The majority of life cycle inventory (LCI) studies assume that computation parameters are constants or fixed functions of time. This assumption limits the opportunities to account for temporal effects because it precludes consideration of the dynamics of the product system.     

Centres of diversity quantified—A maximum variance approach to a biogeographic problem

Summary A quantitative method that optimizes the mapping of species diversity in phytogeographic studies is described. Diversity is computed on the basis of species number per unit area. The optimal size of unit area for which diversity is computed is held to be that which maximises the diversity difference between species-rich and species-poor regions. An example is given using Turkish Papaver. A very high correspondence is found between intuitive insights based on long study and the computer-generated diversity maps. Phytogeographic elements were also determined by computer after gridding Turkey at the scale discovered to be optimal for diversity and scoring the grid squares for presence-absence of each species. In this case, too, quite high correspondence was found between the computer and intuitive results.Nomenclature follows Cullen (1965).The authors express their thanks to Mr. K. Roberts, University of Western Ontario Computing Centre of writing the original maximum variance program and to the National Research Council of Canada for supporting the computing side of the project.