Eye-tracking with nonhuman primates is now more accessible than ever before

Human and nonhuman primates rely almost exclusively on vision for social communication. Therefore, tracking eye movements and examining visual scan paths can provide a wealth of information about many aspects of primate social information processing. Although eye-tracking techniques have been utilized with humans for some time, similar studies in nonhuman primates have been less frequent over recent decades. This has largely been owing to the need for invasive manipulations, such as the surgical implantation of devices to limit head movement, which may not be possible in some laboratories or at some universities, or may not be congruent with some experimental aims (i.e., longitudinal studies). It is important for all nonhuman primate researchers interested in visual information processing or operant behavior to realize that such invasive procedures are no longer necessary. Here, we briefly describe new methods for fully noninvasive video eye-tracking with adult rhesus monkeys (Macaca mulatta). We also describe training protocols that require only ～30 days to accomplish and quality control measures that promote reliable data collection. It is our hope that this brief overview will reacquaint nonhuman primate researchers with the benefits of eye-tracking and promote expanded use of this powerful methodology.     

Stretching skin: undermining is more important than intraoperative expansion

The efficacy of intraoperative expansion in reducing the tension of wound closure was tested in young pigs. The young piglet as a model for studying human skin was characterized by finding a close similarity between the modulus of elasticity of young piglet skin and human abdominoplasty and mammaplasty skin (range 12.8 to 23.7 N/mm2 for piglet skin, 14.3 to 19 N/mm2 for human skin). The tension required to close a standardized wound was determined before undermining, after undermining, and finally after intraoperative expansion. These measurements were performed in 10 young pigs with an average weight of 11.5 kg. Undermining the wound edges resulted in a significant decrease in the force required to close the wounds (p less than 0.0001). Intraoperative expansion did not significantly decrease the tension. Previous work showing the importance of site and direction of pull on the tension for wound closure was confirmed in this study. Analysis of variance demonstrated that the tension required to close a standard wound is greater high on the pig's back than near the belly and near the shoulder as opposed to the hip for midflank wounds (p less than 0.0001). Increasing the extent of undermining from 62 to 136 cm2 significantly decreased the tension for wound closure (p less than 0.05). Further undermining did not result in a significant decrease in wound closure tension. In this model, intraoperative expansion offers no advantage over simple undermining. We suggest that the benefit reported by clinicians using intraoperative expansion may derive from an increase in the extent of undermining required to place expanders under the wound margins.     

Corticolous arthropods under climatic fluctuations: compensation is more important than migration

Animals can cope with fluctuating climates by physiological tolerance, tracking of climatic fluctuations (migration) and compensatory redistribution among (micro)habitats (compensation). Compensation is less demanding and thus more important than migration at large geographic scales. It is not clear however which strategy is more important at the small scale of a microhabitat landscape. I investigated how six arthropod species (Collembola, Oribatei, Psocoptera, Isopoda) respond to microclimatic fluctuations at the surface of exposed tree trunks. Across a nine-month period I characterized the microclimatic zonation of 299 trunks, and focally sampled the arthropods from different microhabitat types (different cryptogam species and bark crevices) within different microclimatic zones. I found that compensatory microhabitat-use was a general phenomenon. The distribution of all species across microhabitats was influenced significantly by ambient microclimate. Also, the arthropods' microhabitat use changed throughout their ontogeny, and microhabitats were used even if they were rare. Most interestingly, the arthropods responded to microclimatic fluctuations primarily by redistribution among microhabitats and less by fluctuations of overall abundances across all microhabitats. Hence compensation was more important than migration. The animals moved for centimeters to decimeters rather than for decimeters to meters; they perceived and utilized their environment primarily at the finest, but also most complex scale. This has implications for the resilience of arthropod populations, their interactions with cryptogams and the turnover of species between macrohabitats.     

When feeling is more important than seeing in sensorimotor adaptation

Perception and action are based on information from multiple sensory modalities. For instance, both vision and proprioception provide information about hand position, and this information is integrated to generate a single estimate of where the hand is in space. Classically, vision has been thought to dominate this process, with the estimate of hand position relying more on vision than on proprioception. However, an optimal integration model that takes into account the precision of vision and proprioception predicts that the weighting of the two senses varies with direction and that the classical result should only hold for specific spatial directions. Using an adaptation paradigm, we show that, as predicted by this model, the visual-proprioceptive integration varies with direction. Variation with direction was so strong that, in the depth direction, the classical result was reversed: the estimate relies more on proprioception than on vision. These results provide evidence for statistically optimal integration of information from multiple modalities.     

Why proof of safety is much more difficult than proof of hazard

On the basis of simple, generally accepted biostatistical and public health principles, it is shown that for environmental health hazards a proof of safety is much more difficult than a proof of hazard. The effective sample sizes required for proof of safety are orders of magnitude greater than what is feasible in biostatistical-epidemiological studies. Although many assurances of safety "in the name of science" have been issued by government agencies and others, few if any of these assurances are statistically valid.     

The DNA double-strand break response pathway: becoming more BRCAish than ever

Breast carcinoma is the leading cause of cancer incidence, and second in cancer mortality to lung cancer, in women of the Western hemisphere. Germ line mutations in the breast cancer susceptibility gene, BRCA1, is responsible for half of all cases of hereditary breast cancer, which constitutes about 5-10% of all cases of breast cancer. Current hypothesis has ascribed a role for Brca1 in maintaining genomic stability, through its involvement in cellular response pathway to the DNA double-strand breaks (DSB). DNA DSB, which are the most deleterious form of DNA damage, are repaired through a series of coordinated steps embedded in a signal transduction pathway that ultimately ensure the elimination of potentially harmful mutations to the genome. This pathway can be crudely divided into a primary and secondary phase. The primary response phase is initiated by sensor proteins that activate transducer protein kinases Atm and Atr, which target downstream effector proteins, such as Chk1 and Chk2, to elicit the secondary response phase. Brca1 has been intimately linked with various aspects of this signaling pathway. However, the precise role of Brca1 in this process remains unclear. In this review, we will provide a simple model in an attempt to clarify the role of Brca1 during cellular response to DNA DSB.     

A broader ecological context to habitat fragmentation: Why matrix habitat is more important than we thought

Abstract. Consequences of habitat fragmentation have garnered much attention over the past few decades. The resulting literature has been useful for understanding how land‐use changes influence population viability and community structure, but we are still hampered by a major aspect of the conceptual framework within which most fragmentation work arises. Specifically, habitat between fragments (‘matrix’) is usually treated as uniform and ecologically irrelevant. However, recent work on animals shows that matrix habitat can profoundly influence within‐fragment dynamics. We review related evidence for plants. Various matrix types (e.g. clear‐cutting, agriculture, or urbanization) can act in different ways to alter resource availability and movement of pollinators, seed dispersers, and herbivores. Inclusion of matrix qualities in fragmentation studies is further complicated since most matrices are not static; sites in which timber harvesting or agriculture occur develop through succession or change as crops are rotated, respectively, such that their influence on within‐fragment processes vary temporally. Also, many plants are not restricted to remnants of original habitat. Using studies of forest understory plants, we summarize work showing how diversity can change significantly through time in matrix. Understanding the persistence of a species across fragmented landscapes will require more attention to matrix habitat, and to the species utilizing the matrix.     

Competition as a demolition derby: why tolerating competitors is more important than suppressing them

Tolerance and suppression are distinct components of competition among plants, and recognizing how they affect competitive outcomes is important for understanding the mechanisms and consequences of competition. We used simulations informed by experimental trials to ask whether tolerance or suppression of competitors was more important for the survival of native plants experiencing competition with an exotic invasive species. When competition was pairwise, tolerance and suppression contributed equally to competitive rank in simulations. However, when multiple native genotypes competed together against an invader, the ability to tolerate competition was up to 50 times more important than the ability to suppress the invader. In two-competitor communities the chief advantage of suppressing competitors was a global decrease in their abundance, but this advantage did not exist in communities of multiple competitors – which is more representative of natural conditions – because decreased competitor abundance benefited all plants regardless of their competitive ability. We suggest that this concept is analogous to a ‘demolition derby,' an automotive contest where participants attempt to have the last functional vehicle on the playing field. Because strong suppressors share the benefits of eliminating competitors with other remaining competitors, we propose that tolerance of competitors is more beneficial than suppression when competition occurs in a multiplayer scenario – in a demolition derby and in nature. This finding has implications for our understanding of how competition influences plant species coexistence, plant community structure and invasion outcomes.     

There is more to autophagy than induction

Considerable attention has been paid to the topic of autophagy induction. In part, this is because of the potential for modulating this process for therapeutic purposes. Of course we know that induced autophagy can also be problematic—for example, when trying to eliminate an established tumor that might be relying on autophagy for its own cytoprotective uses. Accordingly, inhibitory mechanisms have been considered; however, the corresponding studies have tended to focus on the pathways that block autophagy under noninducing conditions, such as when nutrients are available. In contrast, relatively little is known about the mechanisms for inhibiting autophagy under inducing conditions. Yet, this type of regulation must be occurring on a routine basis. We know that dysregulation of autophagy, e.g., due to improper activation of Beclin 1 leading to excessive autophagy activity, can cause cell death.¹ Pattingre S, Tassa A, Qu X, Garuti R, Liang XH, Mizushima N, et al. Bcl-2 antiapoptotic proteins inhibit Beclin 1-dependent autophagy. Cell 2005; 122:927 - 39; http://dx.doi.org/10.1016/j.cell.2005.07.002; PMID: 16179260 [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] Accordingly, we assume that during starvation or other inducing conditions there must be a mechanism to modulate autophagy. That is, once you turn it on, you do not want to let it continue unchecked. But how is autophagy downregulated when the inducing conditions still exist?     

Clinician gender is more important than gender concordance in quality of HIV care

Background: Previous studies have examined the impact of physician gender and gender concordance on preventive care, satisfaction, and communication. Less is known about how physician gender and gender concordance affect care for chronic illnesses, including HIV.Objective: This study sought to determine whether patient-clinician gender concordance (patient and clinician are of the same gender) influences receipt of protease inhibitor (PI) therapy and ratings of care among HIV-infected patients.Methods: We reviewed data from 1860 patients and 397 clinicians in the HIV Cost and Services Utilization Study, a nationally representative the association between gender concordance and time to first PI use, and multivariable logistic regression was utilized to examine the association of gender concordance with patients' problems with care and their overall rating of care.Results: Patients who had a male clinician received PIs earlier than those who had a female clinician (adjusted time ratio = 0.69 for having a male vs having a female clinician; P ≤ 0.01). Gender concordance was not a significant predictor of time to PI use. Gender discordance was associated with problems with feeling respected by clinicians. Female patients with a male clinician were most likely, and female patients with female clinicians were least likely, to report a problem with being treated with respect (P ≤ 0.01 for the interaction term). Gender discordance was not associated with other problems with care or with overall ratings of care.Conclusions: Gender discordance was associated with perceived problems of being treated with respect by clinicians, but not with time to receipt of PIs, overall ratings of care, coordination of care, or obtaining information. The perception of not being respected may represent a significant barrier to care that is particularly worse for women, in that most HIV-infected women receive their care from male clinicians.     

Structure is more important than physiology for estimating intracanopy distributions of leaf temperatures

Estimating leaf temperature distributions (LTDs) in canopies is crucial in forest ecology. Leaf temperature affects the exchange of heat, water, and gases, and it alters the performance of leaf‐dwelling species such as arthropods, including pests and invaders. LTDs provide spatial variation that may allow arthropods to thermoregulate in the face of long‐term changes in mean temperature or incidence of extreme temperatures. Yet, recording LTDs for entire canopies remains challenging. Here, we use an energy‐exchange model (RATP) to examine the relative roles of climatic, structural, and physiological factors in influencing three‐dimensional LTDs in tree canopies. A Morris sensitivity analysis of 13 parameters showed, not surprisingly, that climatic factors had the greatest overall effect on LTDs. In addition, however, structural parameters had greater effects on LTDs than did leaf physiological parameters. Our results suggest that it is possible to infer forest canopy LTDs from the LTDs measured or simulated just at the surface of the canopy cover over a reasonable range of parameter values. This conclusion suggests that remote sensing data can be used to estimate 3D patterns of temperature variation from 2D images of vegetation surface temperatures. Synthesis and applications. Estimating the effects of LTDs on natural plant–insect communities will require extending canopy models beyond their current focus on individual species or crops. These models, however, contain many parameters, and applying the models to new species or to mixed natural canopies depends on identifying the parameters that matter most. Our results suggest that canopy structural parameters are more important determinants of LTDs than are the physiological parameters that tend to receive the most empirical attention.     

Speciation in Caucasian lizards: climatic dissimilarity of the habitats is more important than isolation time

Given sufficient time and limited gene flow, evolutionary lineages tend to transform into separate species. Mechanisms preventing assimilation during repeated gene‐flow events include divergent adaptations and the development of pre‐ or postzygotic isolation. We analysed the morphological and genetic boundaries of three species of the rock lizard clade Darevskia ‘rudis’ (Darevskia rudis, Darevskia valentini, and Darevskia portschinskii) in relation to the environment, and tried to reconstruct evolutionary pathways underlying the observed separation among the species. We studied the geographic distribution of the scalation traits, microsatellite genotypes, and mitochondrial haplotypes. Our analyses showed consistent morphological and genetic patterns at the centre of the ranges for each species, but asymmetric distribution of alleles and scalation characters within the current contact zones among the species. The genetic and morphological diversification of the clade has been shaped during glacial isolation in an area of Southern Caucasus, away from the Black Sea Coast. The ancestral lineage of D. portschinskii separated from the common D. rudis–D. valentini lineage in the middle Pleistocene, and the two latter lineages separated in relatively recent geological time. Neither of the lineages attained complete lineage sorting; moreover, isolation and migration modelling have helped to detect recombinant gene flow from D. rudis to D. portschinskii (but not to D. valentini). This is most likely linked with climatically more similar suitable habitats between D. rudis and D. portschinskii than between D. valentini and the other two species. In itself, the isolation period was insufficient for the development of intrinsic isolation mechanisms in the system studied. Thus, differential landscape‐dependent selection within the contact zones is likely to have triggered the rapid development of isolation mechanisms. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 876–892.