What can we learn from Daphnia filtering screens?

The relative filtering setae length (RFSL the length of filteringsetae on the third pair of thoracic limbs expressed as a percent of carapace length) was determined in three developmentalcategories of a reservoir population of Daphnia galeata andits relationship to phytoplankton fluctuation. RFSL of adultfemales immediately after moulting reflects the current foodconditions in the reservoir (higher RFSL at lower food level,and vice versa), whereas RFSL of adult females close to moultingreflects the food conditions several days or weeks ago. RFSLof juvenile animals reacts the most quickly to changing foodconditions, provided the temperature allows frequent moulting.Higher RFSL can also indicate poor-quality food for daphnids,in situations when food quantitative parameters (such as chlorophylla) show high values.     

What can we learn about protein folding from Ising-like models?

Ising-like models have been remarkably successful in reproducing all the experimental data available on the equilibrium and kinetics of secondary structure formation in short peptides. Over the past two years, very similar models have been used to predict the folding of complete proteins, with encouraging results. Although Ising-like models are probably too simple to describe all aspects of protein folding, the results obtained so far indicate that they can play a critical role in the study of protein folding by bridging the gap between experiment and more detailed theoretical approaches.     

Antiviral strategies: What can we learn from natural reservoirs?

Viruses cause many severe diseases in both plants and animals, urging us to explore new antiviral strategies. In their natural reservoirs, viruses live and replicate while causing mild or no symptoms. Some animals, such as bats, are the predicted natural reservoir of multiple viruses, indicating that they possess broad-spectrum antiviral capabilities. Mechanisms of host defenses against viruses are generally studied independently in plants and animals. In this article, we speculate that some antiviral strategies of natural reservoirs are conserved between kingdoms. To verify this hypothesis, we created null mutants of 10-formyltetrahydrofolate synthetase (AtTHFS), an Arabidopsis thaliana homologue of methylenetetrahydrofolate dehydrogenase, cyclohydrolase and formyltetrahydrofolate synthetase 1 (MTHFD1), which encodes a positive regulator of viral replication in bats. We found that disruption of AtTHFS enhanced plant resistance to three different types of plant viruses, including the tomato spotted wilt virus (TSWV), the cucumber mosaic virus (CMV) and the beet severe curly top virus (BSCTV). These results demonstrate a novel antiviral strategy for plant breeding. We further discuss the approaches used to identify and study natural reservoirs of plant viruses, especially those hosting many viruses, and highlight the possibility of discovering new antiviral strategies from them for plant molecular breeding and antiviral therapy.     

Vision for navigation: What can we learn from ants?

The visual systems of all animals are used to provide information that can guide behaviour. In some cases insects demonstrate particularly impressive visually-guided behaviour and then we might reasonably ask how the low-resolution vision and limited neural resources of insects are tuned to particular behavioural strategies. Such questions are of interest to both biologists and to engineers seeking to emulate insect-level performance with lightweight hardware. One behaviour that insects share with many animals is the use of learnt visual information for navigation. Desert ants, in particular, are expert visual navigators. Across their foraging life, ants can learn long idiosyncratic foraging routes. What's more, these routes are learnt quickly and the visual cues that define them can be implemented for guidance independently of other social or personal information. Here we review the style of visual navigation in solitary foraging ants and consider the physiological mechanisms that underpin it. Our perspective is to consider that robust navigation comes from the optimal interaction between behavioural strategy, visual mechanisms and neural hardware. We consider each of these in turn, highlighting the value of ant-like mechanisms in biomimetic endeavours.     

What can we learn about amphiphile-membrane interaction from model lipid membranes?

Surface-active amphiphiles find applications in a wide range of areas of industry such as agrochemicals, personal care, and pharmaceuticals. In many of these applications, interaction with cell membranes is a key factor for achieving their purpose. How do amphiphiles interact with lipid membranes? What are their bases for membrane specificity? Which biophysical properties of membranes are susceptible to modulation by amphiphilic membrane-effectors? What aspects of this interaction are important for performing their function? In our work on membrane biophysics over the years, questions like these have arisen and we now share some of our findings and discuss them in this review. This topic was approached focusing on the membrane properties and their alterations rather than on the amphiphile structure requirements for their interaction. Here, we do not aim to provide a comprehensive list of the modes of action of amphiphiles of biological interest but to help in understanding them.     

Immunity to vacuolar pathogens: What can we learn from Legionella?

Intracellular pathogens can manipulate host cellular pathways to create specialized organelles. These pathogen-modified vacuoles permit the survival and replication of bacterial and protozoan microorganisms inside of the host cell. By establishing an atypical organelle, intracellular pathogens present unique challenges to the host immune system. To understand pathogenesis, it is important to not only investigate how these organisms create unique subcellular compartments, but to also determine how mammalian immune systems have evolved to detect and respond to pathogens sequestered in specialized vacuoles. Recent studies have identified genes in the respiratory pathogen Legionella pneumophila that are essential for establishing a unique endoplasmic reticulum-derived organelle inside of mammalian macrophages, making this pathogen an attractive model system for investigations on host immune responses that are specific for bacteria that establish vacuoles disconnected from the endocytic pathway. This review will focus on the host immune response to Legionella and highlight areas of Legionella research that should help elucidate host strategies to combat infections by intracellular pathogens.     

Keeping your vascular integrity: What can we learn from fish?

The cardiovascular system has the life-providing task of delivering oxygen and any flaw in this system can be life-threatening. This has encouraged extensive studies to elucidate the mechanisms behind cardiovascular development/homeostasis. The zebrafish has emerged as a formidable tool to speed up this quest, as illustrated in a recent issue of Nature Genetics.1 Baculovirus IAP repeat c2 (BIRC2), also termed cellular inhibitor of apoptosis (cIAP)-1, was found to specifically prevent endothelial cells (ECs, lining the inside of vessels) from going into suicide mode ('apoptosis') and so preserve vessel integrity. Here, we summarize the factors determining vascular integrity and elaborate on the suitability of the zebrafish to study this phenomenon.     

What can we learn from the optically recorded epicardial action potential?

Optical mapping using voltage-sensitive fluorescent dyes has become a major tool for studying excitation propagation in the heart. Computational and experimental studies have indicated that the optical upstroke morphology reflects the orientation of the subsurface excitation front. In a recent whole heart computational study performed by Bishop et al. (Bishop, M. J., B. Rodriguez, J. Eason, J. P. Whiteley, N. Trayanova, and D. J. Gavaghan. 2006. Synthesis of voltage-sensitive optical signals: application to panoramic optical mapping. Biophys. J. 90:2938-2945), an example was provided of two different directions of propagation having nevertheless very similar epicardial optical upstrokes. The goal of this comment is to clarify the interpretation of optical upstroke morphologies and reconcile the results obtained by Bishop et al. with previous computational and experimental studies.     

Towards Transgenic Primates: What can we learn from mouse genetics?

Considering the great physiological and behavioral similarities with humans, monkeys represent the ideal models not only for the study of complex cognitive behavior but also for the preclinical research and development of novel therapeutics for treating human diseases. Various powerful genetic technologies initially developed for making mouse models are being explored for generating transgenic primate models. We review the latest genetic engineering technologies and discuss the potentials and limitations for systematic production of transgenic primates. Supported by Funding from GRA, NIMH and NIA.     

What can we learn from noncoding regions of similarity between genomes?

Background  

In addition to known protein-coding genes, large amounts of apparently non-coding sequence are conserved between the human and mouse genomes. It seems reasonable to assume that these conserved regions are more likely to contain functional elements than less-conserved portions of the genome.     

What can we still learn from the electrochromic band-shifts in Photosystem II?

Electrochromic band-shifts have been investigated in Photosystem II (PSII) from Thermosynechoccocus elongatus. Firstly, by using Mn-depleted PsbA1-PSII and PsbA3-PSII in which the Q_X absorption of Phe_D1 differs, a band-shift in the Q_X region of Phe_D2 centered at ~ 544 nm has been identified upon the oxidation, at pH 8.6, of Tyr_D. In contrast, a band-shift due to the formation of either Q_A^•- or Tyr_Z^• is observed in PsbA3-PSII at ~ 546 nm, as expected with E130 H-bonded to Phe_D1 and at ~ 544 nm as expected with Q130 H-bonded to Phe_D1. Secondly, electrochromic band-shifts in the Chla Soret region have been measured in O₂-evolving PSII in PsbA3-PSII, in the PsbA3/H198Q mutant in which the Soret band of P_D1 is blue shifted and in the PsbA3/T179H mutant. Upon Tyr_Z^•Q_A^•- formation the Soret band of P_D1 is red shifted and the Soret band of Chl_D1 is blue shifted. In contrast, only P_D1 undergoes a detectable S-state dependent electrochromism. Thirdly, the time resolved S-state dependent electrochromism attributed to P_D1 is biphasic for all the S-state transitions except for S₁ to S₂, and shows that: i) the proton release in S₀ to S₁ occurs after the electron transfer and ii) the proton release and the electron transfer kinetics in S₂ to S₃, in T. elongatus, are significantly faster than often considered. The nature of S₂Tyr_Z^• is discussed in view of the models in the literature involving intermediate states in the S₂ to S₃ transition.     

What can we learn about ecology and evolution from the fossil record?

The increased application of abundance data embedded within a more detailed and precise environmental context is enabling paleontologists to explore more rigorously the dynamics and underlying processes of ecological and evolutionary change in deep time. Several recent findings are of special theoretical interest. Community membership is commonly more stable and persistent than expected by chance, even in the face of the extreme environmental changes of the Ice Ages, and major evolutionary novelties commonly lie dormant for tens of millions of years before the ecological explosions of the clades that possess them. As we discuss here, questions such as these cannot be adequately addressed without the use of the fossil record.     

Phylloquinone, what can we learn from plants?

The plant plasma membrane contains redox proteins able to mediate a trans-membrane electron flow. This electron flow might be responsible for the generation of the active oxygen species observed as a reaction to pathogen attack or stress. Vitamin K1 could be identified as a possible lipid soluble electron carrier in plant plasma membrane preparations. Such a function would be analogous to coenzyme Q in animal plasma membranes. What we are going to outline in this contribution is a concept of how the electron transport system of the plant plasma membrane could interact with quinones, thus contributing to the metabolism of free radicals in plants.     

What can one learn from two-state single-molecule trajectories?

A time trajectory of an observable that fluctuates between two values (say, on and off), stemming from some unknown multisubstate kinetic scheme, is the output of many single-molecule experiments. Here we show that when all successive waiting times along the trajectory are uncorrelated the on and the off waiting time probability density functions contain all the information. By relating the lack of correlation in the trajectory to the topology of kinetic schemes, we can immediately specify those kinetic schemes that are equally consistent with experiment, and cannot be differentiated by any sophisticated analyses of the trajectory. Correlated trajectories, however, contain additional information about the underlying kinetic scheme, and we consider the strategy that one should use to extract it.