The river echoes with laughter: a child‐centred analysis of social change in Amazonia

This article examines radical social, cultural, and political changes taking place in Amazonia from the perspective of indigenous children and youth: a group who, despite their demographic prevalence, have received limited attention in the regional literature. Drawing on fieldwork with Matses people in Peru, I consider how children and youth are playing a critical role in the transition from a hunter‐gatherer, forest‐based society towards a riverine lifestyle that is increasingly engaged in trade, the market economy, and exchanges with chotac, or non‐indigenous people. I argue that by engaging with their surroundings through playing and working, Matses children are becoming affectively attached to some parts of the world rather than others. This represents a purposeful shift from the lifestyle and worldviews of older generations and highlights how children are active agents who shape possible future directions of Matses society and transform the community's relationships with the world. Accordingly, I propose a child‐centred view of social change that seeks to demonstrate the implications of children's creativity and agency for society at large and its future development.     

Switching Between Cooperation and Competition in the Use of Extracellular Glucose

This paper addresses some questions related to the evolution of cooperative behaviors, in the context of energetic metabolism. Glycolysis can perform either under a dissipative working regime suitable for rapid proliferation or under an efficient regime that entails a good modus operandi under conditions of glucose shortage. A cellular mechanism allowing switching between these two regimes may represent an evolutionary achievement. Thus, we have explored the conditions that might have favored the emergence of such an accommodative mechanism. Because of an inevitable conflict for resources between individual interests and the common good, rapid and inefficient use of glucose is always favored by natural selection in spatially homogeneous environment, regardless of the external conditions. In contrast, when the space is structured, the behavior of the system is determined by its free energy content. If the fuel is abundant, the dissipative strategy dominates the space. However, under famine conditions the efficient regime represents an evolutionary stable strategy in a Harmony game. Between these two extreme situations, both metabolic regimes are engaged in a Prisoner’s Dilemma game, where the output depends on the extracellular free energy. The energy transition values that lead from one domain to another have been calculated. We conclude that an accommodative mechanism permitting alternation between dissipative and efficient regimes might have evolved in heterogeneous and highly fluctuating environments. Overall, the current work shows how evolutionary optimization and game-theoretical approaches can be complementary in providing useful insights into biochemical systems. Reviewing Editor: Dr. Antony Dean     

Brassinosteroids as Metahormones: Evidence for their Specific Influence during the Critical Period in Sorghum Development

Abstract: In Sorghum bicolor, the effect of brassinosteroid (BR) treatments on blade elongation depends both on concentration and on the stage of development. A specific period of increase in sensitivity to BR is reported during early vegetative development. It coincides with emergence of a critical period during which the between-organs relationship is readjusted as a function of new developmental events or new environmental conditions. Accordingly, the influence of BR cannot be completely understood without separating its effects during stable phases (phenophases) and during critical periods. A high level of redundancy exists in networks of regulation, so that modifications due to BR treatments generally remain cryptic. Nevertheless, it is shown that BR affects the pattern of relationships between organs, confirming its involvement in emergence of a new network of regulation. It is suggested that, during critical periods, brassinosteroids act as "metahormones" integrating the new emerging regulation network by triggering changes in cellular sensitivity to PGRs.     

Spatial correlation as leading indicator of catastrophic shifts

Generic early-warning signals such as increased autocorrelation and variance have been demonstrated in time-series of systems with alternative stable states approaching a critical transition. However, lag times for the detection of such leading indicators are typically long. Here, we show that increased spatial correlation may serve as a more powerful early-warning signal in systems consisting of many coupled units. We first show why from the universal phenomenon of critical slowing down, spatial correlation should be expected to increase in the vicinity of bifurcations. Subsequently, we explore the applicability of this idea in spatially explicit ecosystem models that can have alternative attractors. The analysis reveals that as a control parameter slowly pushes the system towards the threshold, spatial correlation between neighboring cells tends to increase well before the transition. We show that such increase in spatial correlation represents a better early-warning signal than indicators derived from time-series provided that there is sufficient spatial heterogeneity and connectivity in the system.     

Le phenomene d'heteroblastie chez les vegetaux: Comment l'expliquer?

Heteroblastic development is often observed in Cormophytae, but it can also be characterized in Thallophytae as shown by the detailed investigation of the development of the algaAntithamnion plumula (Ceramiaceae, Rhodophyta). In this species, heteroblasty concerns (i) dimensional variables (such as pleuridia length and lateral cladome first tagma length) and (ii) variables that characterize the cell growth kinetics (main axis cells). Apex curvature also varies during ontogenesis.The generality of the property in plants led to search for its origin: apical meristem own dynamics, ontogenetic evolution of internal relationships, dialectical relationships between the plant and its environment.Some models were put forward to accout for the development ofAntithamnion but did not take into account the heteroblasty phenomenon. The investigations presented here are a first attempt at representation through formal grammar, based on double wall map systems. The model leads to the assumption of the occurrence of an oscillatory mechanism associated with a threshold that determines both qualitatively (axial cell of the cladomophoric or pleuridiophic type) and quantitatively the development of the whorls.

     

Kinetic characterization of enhanced lipase activity on oil bodies

Enzyme access, kinetic behavior, and protein–protein interactions are critical for explaining reaction of the metabolites contained within the myriad compartments of biological systems. To explore these relationships, the reaction kinetics of oil bodies versus oil emulsions as substrates for lipolytic reactions were measured. The initial rate of hydrolysis for the oil body system was comparatively very low due to a brief latency period. However, the complete activation of the lipase at the interface resulted in an enzyme–membrane complex that was catalytically enhanced 3–15-fold over the emulsion system for substrate concentrations in the measured range of approximately 1–5.5 mM. This disparity is explained by the availability of substrate to the enzyme active site (defined as the availability parameter “A”) which varies between the two substrates by 40-fold. A simple hyperbolic kinetic mechanism is proposed with K _m replaced by the parameter, A, to account for this phenomenon, leading to a maximum rate of approximately 1450 IU/mg protein. The interaction is verified through separation of the enzyme–membrane complex which shows nearly double the activity towards an emulsified soybean oil substrate (activity ratio of 5:3) when compared to the native enzyme.     

Biological and spatial structure of an early classic period cemetery at Charco Redondo,Oaxaca

This article presents an analysis of biological and spatial patterning of an Early Classic (A.D. 250–500) Chatino cemetery at the archaeological site of Charco Redondo, located in the lower Río Verde Valley, Oaxaca, Mexico. The Early Classic was a time of political instability positioned between two phases of state‐level centralization within the coastal valley. The communal cemetery at Charco Redondo adds significantly to the inventory of excavated graves from this time period and provides novel data on mortuary practices during a critical phase in the development of state level polities in the region. Cluster analysis of mortuary data is combined with intracemetery biodistance approaches to reconstruct how the Charco Redondo cemetery was organized with respect to biological relationships. Cluster analysis of mortuary data identified three groupings of burials. Multidimensional scaling of Euclidean distances and Gower coefficients based on 45 odontometric and 13 dental morphological variables suggests a strong relationship between grave characteristics and locations and phenotypic variation. In other words, the cemetery at Charco Redondo appears biologically kin‐structured. The communal nature of the cemetery conflicts with the assumed “household” burial model for this time period. We propose the observed combination of features represents a transitional practice in which aspects of community, kin, and individual identity were signaled simultaneously within the funerary environment during a time of political transition in the Valley. This article highlights the utility of intracemetery biodistance analyses for examining dimensions of kinship, “house,” and community throughout Mesoamerica where overarching models often mask regional variability. Am J Phys Anthropol 152:217–229, 2013. © 2013 Wiley Periodicals, Inc.     

The mitochondrial permeability transition pore: an evolving concept critical for cell life and death

In this review, we summarize current knowledge of perhaps one of the most intriguing phenomena in cell biology: the mitochondrial permeability transition pore (mPTP). This phenomenon, which was initially observed as a sudden loss of inner mitochondrial membrane impermeability caused by excessive calcium, has been studied for almost 50 years, and still no definitive answer has been provided regarding its mechanisms. From its initial consideration as an in vitro artifact to the current notion that the mPTP is a phenomenon with physiological and pathological implications, a long road has been travelled. We here summarize the role of mitochondria in cytosolic calcium control and the evolving concepts regarding the mitochondrial permeability transition (mPT) and the mPTP. We show how the evolving mPTP models and mechanisms, which involve many proposed mitochondrial protein components, have arisen from methodological advances and more complex biological models. We describe how scientific progress and methodological advances have allowed milestone discoveries on mPTP regulation and composition and its recognition as a valid target for drug development and a critical component of mitochondrial biology.     

Perturbed reproductive development in salt-treated Sorghum bicolor: a consequence of modifications in regulation networks?

In Sorghum bicolor, tolerance to salinity is improved by a 3-week treatment with 150 mM NaCl during early vegetative development. However, a strong decrease in fertility is also observed, suggesting that reproductive development becomes perturbed by this adaptive response to salinity. This study is an attempt to clarify the origin of such a paradoxical phenomenon. The relationships between end-cycle characters are modified by the NaCl treatment: some linkages disappear, while others are strengthened, especially those linking fertility with plant height. In parallel, a transient reduced level of linkage between leaf characters is observed around the unfolding of the eighth to the tenth leaves, defining a critical period in vegetative development separating two discrete phases. A relationship is observed between events occurring during this short critical period and the NaCl-induced perturbations in fertility. This suggests that reproductive development is conditioned by the influence of salinity on events occurring during a short period of vegetative development, independently of the level of tolerance to salinity quantified by the rate of vegetative growth.     

Slowing down in spatially patterned ecosystems at the brink of collapse

Predicting the risk of critical transitions, such as the collapse of a population, is important in order to direct management efforts. In any system that is close to a critical transition, recovery upon small perturbations becomes slow, a phenomenon known as critical slowing down. It has been suggested that such slowing down may be detected indirectly through an increase in spatial and temporal correlation and variance. Here, we tested this idea in arid ecosystems, where vegetation may collapse to desert as a result of increasing water limitation. We used three models that describe desertification but differ in the spatial vegetation patterns they produce. In all models, recovery rate upon perturbation decreased before vegetation collapsed. However, in one of the models, slowing down failed to translate into rising variance and correlation. This is caused by the regular self-organized vegetation patterns produced by this model. This finding implies an important limitation of variance and correlation as indicators of critical transitions. However, changes in such self-organized patterns themselves are a reliable indicator of an upcoming transition. Our results illustrate that while critical slowing down may be a universal phenomenon at critical transitions, its detection through indirect indicators may have limitations in particular systems.     

Eat or Not to Eat: Reversed Sexual Cannibalism as a Male Foraging Strategy in the Spider Micaria sociabilis (Araneae: Gnaphosidae)

Reversed sexual cannibalism represents an unusual situation in which a male kills and consumes a female. We examined this rare phenomenon in the spider Micaria sociabilis, whose males were observed to regularly cannibalise old females. In this study, we investigated male motivation for such behaviour in the light of ecological conditions such as mate availability and prey availability. We found that male cannibalism is not affected by short‐term starvation but rather by male feeding history during the ontogenetic development in combination with prey availability during the adult stage. Males from the summer generation reached bigger sizes than males from the spring generation and females from both generations. They developed in the period with exceptionally high prey occurrence, but when they reached the adult stage, the prey availability decreased. In this period, we observed the highest frequency of cannibalism, however, only when the sex ratio was female biased. Reversed sexual cannibalism in M. sociabilis seems to represent an advantageous male foraging strategy, which is affected by prey availability and male feeding history, tuned by sex ratio and directed towards females of inferior quality.     

Effects of the Development of Thyroid and Sex Glands on the Synthesis of Brain Tubulin in Chick and Mouse Embryos

Using the specific affinity of tubulin for colchicine and the strong absorption of tubulin to DEAEion exchangers at neutral pH and moderate ionic strength,the amounts of tubulin in the brain fromboth mice and chicks during different developing stages were measured by ~3H-colchicine assay(expressed as colchicine binding activity).The results show that the rate oftubulin synthesis reacheda peak value during the critical period of brain development.This is exactly the period during whichthe organization and function of thyroid are being perfected.Besides,during breeding period,thedifference of tubulin contents between male and female is significant(P<0.001).The synthesis oftubulin is strictly sex dependent(this phenomenon appeared only during sex maturation stage).It issuggested that sexual hormones might exert their effect on tubulin synthesis.     

Wing morphology of a new Cretaceous praying mantis solves the phylogenetic jigsaw of early‐diverging extant lineages

The extremely derived morphology and behaviour of extant praying mantises combined with a scarce record of fossil relatives introduce significant challenges to tracing their evolution from Palaeozoic stem‐dictyopterans. Extant members of Chaeteessidae, Mantoididae and Metallyticidae could be invaluable to resolving the mantodean tree, yet their inclusion in phylogenetic analyses led to conflicting hypotheses due to their highly disparate respective morphologies. In this contribution, we present Labradormantis guilbaulti gen. et sp.n. , a new fossil species described from both fore‐ and hind‐wing imprints discovered in the Redmond Mine locality (Late Cretaceous, Cenomanian, Redmond Formation; Labrador, Canada). The examination of its hind‐wing AA2* supports the hypothesis that this structure, unique to Chaeteessidae among extant mantises, is a true vein and that its occurrence represents a plesiomorphy for Mantodea. A parsimony analysis including newly coded wing‐related characters further established that L. guilbaulti gen. et sp.n. displays a unique combination of plesiomorphic and apomorphic character states that situates it within the extinct family Baissomantidae. This dataset resolved the phylogenetic relationships of early‐diverging extant lineages as (Chaeteessidae (Mantoididae (Metallyticidae, Artimantodea))), and suggested that the Eocene Lithophotina floccosa Cockerell might be a close relative of extant metallyticids. It also indicated a trend towards increased modularity within mantis fore‐wings, in contrast with a trend towards increased morphological integration in their hind‐wings, both of which are potentially associated with improved flight performance for modern mantises. This study emphasizes the importance of fossils for resolving phylogenetic relationships and for introducing transitional phenotypes to infer ancient evolutionary trends of extant derived clades.     

Maturation of integrated functions during development. I. Modifications of the regulatory network during transition periods in Sorghum bicolor

Gibberellin (GA) and cytokinin (CK) were exogenously supplied at different periods of the vegetative development in Sorghum bicolor. Growth response to these hormonal treatments differed according to the developmental stage. This reveals the existence of discrete phenophases, each one characterized by a specific sensitivity to plant growth regulations (PGRs). Developmental changes in sensitivity were less accentuated in plants grown in optimal conditions than in plants exposed to 150 mM NaCl. Variations in organ connectance (the level of coordination in growth of the shoot, adventitious roots and seminal root) were analysed during vegetative growth of salt‐treated plants. This analysis shows a temporary decrease in connectance during the transition period between phenophases. From the effect of hormonal treatments on connectance, it was concluded that (i) the transition period coincides with a partial dismantling of the initial regulatory network followed by the emergence of a new network coordinating growth of the different organs; (ii) GA is involved in the process of emergence of a transition period; and (iii) duration of the transition period is considerably enlarged for plants exposed to NaCl stress. This dynamics of alternance of phenophase and transition periods enables the integration of the two modes of action of the PGRs (dose–response and change in sensitivity) within a unified framework.     

Constant rate allocation in nymphal development in species of Hemiptera

Abstract. This study investigated the existence of rate isomorphy (the constant allocation of relative times to different stages of development under different abiotic conditions) in Macrolophus pygmaeus (Hemiptera: Miridae; a phytophagous and predatory insect). Replicated data were used from a range of temperatures regarding (i) the developmental period of each nymphal stage in relation to the total duration of nymph development, when feeding on three host plants either with different prey species or without prey, and (ii) its egg, total nymphal and preoviposition period, on two host plants, with different prey species. The proportion of time required for the development of each nymphal stage of M. pygmaeus is not different among the temperatures or the kind of food available. These proportions ranged among the different host plants, temperatures and prey presence/absence from 17.3–21.8% in the first, 14.5–18.8% in the second, 14.2–18.3% in the third, 16.5–21.0% in the fourth and from 25.4–30.6% in the fifth nymphal stage. Thus, temperature does not significantly affect the proportion of time spent in each nymphal stage and rate isomorphy exists in nymphal development. This phenomenon was also investigated using data from the literature, and it also occurs in several other Hemiptera species. Therefore, there appears to be a constant time allocation in the nymphal development of the higher taxonomic groups of insects. However, for M. pygmaeus, rate isomorphy does not hold when considering egg‐to‐egg development and the relative duration of times to egg hatch, total nymphal development and preoviposition period. The ecophysiological implications of this rate isomorphy phenomenon are discussed in relation to endocrinological mechanisms. Apart from its theoretical interest, the existence of rate isomorphy simplifies studies on the rate of development and the estimation of thermal constants of an insect, which are essential for the prediction of insect population dynamics. It is also proposed that the term ‘rate isomorphy’ does not strictly describe the phenomenon, and it is suggested that ‘constant rate allocation’ would be a more suitable term.     

Effects of starvation on moult cycle and hepatopancreas of Stage I lobster(Homarus americanus) larvae

Effects of feeding and starvation on the moult cycle and on the ultrastructure of hepatopancreas cells were studied in Stage I lobster larvae (Homarus americanus Milne-Edwards). The relative significance of yolk and first food was quite different in larvae originating from two females. This difference was evident also in the amounts of stored lipid in the R-cells of the larval hepatopancreas. Most larvae from one hatch were, in principle, able to develop exclusively with yolk reserves (without food) to the second instar. The larvae from the second hatch showed lecithotrophic development only to the transition between late intermoult and early premoult (Stages C/D₀ of Drachs's moult cycle) of the first larval instar. When initial starvation in this group lasted for 3 days or more, the point of no return (PNR) was exceeded. After the PNR, consumption of food was still possible, but development ceased in the transition C/D₀ or in late premoult (D_3–4). It is suggested that these stages of the moult cycle are critical points were cessation of development and increased mortality are particularly likely in early larval lobsters under nutritional stress. Examination of hepatopancreas R-cells suggested that the PNR is caused by an irreversible loss of the ability to restore lipid reserves depleted during initial starvation. Initial periods of starvation ending before the PNR prolonged mainly Stage D₀ of the same instar (I). During this delay, structural changes in the R-cells caused by the preceding period of starvation were reversed: reduced lipid inclusions, swollen mitochondria, an increased number of residual bodies indicating autolysis, and a reduction of the microvillous processes. Continually starved larvae which showed lecithotrophic development throughout the first instar and were then re-fed after moulting successfully, had later a prolonged intermoult (Stage C) period in the second instar. This shows that, despite occasional lecithotrophy, food is an important factor in early larval development of the lobster.     

Genome‐wide identification and expression analysis reveal the potential function of ethylene responsive factor gene family in response to Botrytis cinerea infection and ovule development in grapes (Vitis vinifera L.)

• The prevention of Botrytis cinerea infection and the study of grape seedlessness are very important for grape industries. Finding correlated regulatory genes is an important approach towards understanding their molecular mechanisms.
• Ethylene responsive factor (ERF) gene family play critical roles in defence networks and the growth of plants. To date, no large‐scale study of the ERF proteins associated with pathogen defence and ovule development has been performed in grape (Vitis vinifera L.). In the present study, we identified 113 ERF genes (VvERF) and named them based on their chromosome locations. The ERF genes could be divided into 11 groups based on a multiple sequence alignment and a phylogenetic comparison with homologues from Arabidopsis thaliana. Synteny analysis and Ka/Ks ratio calculation suggested that segmental and tandem duplications contributed to the expansion of the ERF gene family. The evolutionary relationships between the VvERF genes were investigated by exon–intron structure characterisation, and an analysis of the cis‐acting regulatory elements in their promoters suggested potential regulation after stress or hormone treatments.
• Expression profiling after infection with the fungus, B. cinerea, indicated that ERF genes function in responses to pathogen attack. In addition, the expression levels of most ERF genes were much higher during ovule development in seedless grapes, suggesting a role in ovule abortion related to seedlessness.
• Taken together, these results indicate that VvERF proteins are involved in responses to Botrytis cinerea infection and in grape ovule development. This information may help guide strategies to improve grape production.

     

Household environmental microbiota influences early-life eczema development

Exposure to a diverse microbial environment during pregnancy and early postnatal period is important in determining predisposition towards allergy. However, the effect of environmental microbiota exposure during preconception, pregnancy and postnatal life on development of allergy in the child has not been investigated so far. In the S-PRESTO (Singapore PREconception Study of long Term maternal and child Outcomes) cohort, we collected house dust during all three critical window periods and analysed microbial composition using 16S rRNA gene sequencing. At 6 and 18 months, the child was assessed for eczema by clinicians. In the eczema group, household environmental microbiota was characterized by presence of human-associated bacteria Actinomyces, Anaerococcus, Finegoldia, Micrococcus, Prevotella and Propionibacterium at all time points, suggesting their possible contributions to regulating host immunity and increasing the susceptibility to eczema. In the home environment of the control group, putative protective effect of an environmental microbe Planomicrobium (Planococcaceae family) was observed to be significantly higher than that in the eczema group. Network correlation analysis demonstrated inverse relationships between beneficial Planomicrobium and human-associated bacteria (Actinomyces, Anaerococcus, Finegoldia, Micrococcus, Prevotella and Propionibacterium). Exposure to natural environmental microbiota may be beneficial to modulate shed human-associated microbiota in an indoor environment.     

Seasonal patterns of leaf water relations in four co-occurring forest tree species: Parameters from pressure-volume curves

Summary Leaf water relationships were studied in four widespread forest tree species (Ilex opaca Ait., Cornus florida L., Acer rubrum L., and Liriodendron tulipifera L.). The individuals studied all occurred on the same site and were selected to represent a range of growth forms and water relationships in some of the principal tree species of the region. The water relations of the species were analyzed using the concept of the water potential-water content relationship. The pressure-volume method was used to measure this relationship using leaf material sampled from naturally occurring plants in the field. Water potential components (turgor, osmotic, and matric) were obtained by analysis of the pressure-volume curves.Initial osmotic potentials (the value of the osmotic component at full turgidity) were highest (least negative) at the start of the growing season. They decreased (becoming progressively more negative) as the season progressed through a drought period. Following a period of precipitation at the end of the drought period, initial osmotic potentials increased toward the values measured earlier in the season.Seasonal osmotic adjustments were sufficient in all species to allow maintenance of leaf turgor through the season, with one exception: Acer appeared to undergo some midday turgor loss during the height of the July drought period.In addition to environmental influences, tissue stage of development played a role; young Ilex leaves had higher early season initial osmotic potentials than overwintering leaves from the same tree.The seasonal pattern of initial osmotic potential in Liriodendron and the observed pattern of leaf mortality suggested a possible role of osmotic potentials in the resistance of those leaves to drought conditions. The fraction of total leaf water which is available to affect osmotic potentials, called the osmotic water fraction in this study, was greatest in young tissue early in the season and declined as the season progressed.The results of this study showed that the water potential-water content relationship represents a dynamic mechanism by which plant internal water relations may vary in response to a changing external water-availability regime. The measured water relationships confirmed the relative positions of the species along a water-availability gradient, with Cornus at the wettest end and Ilex at the driest end of the gradient. Acer and Liriodendron were intermediate in their water relations. The spread of these species along a water-availability gradient on the same site suggested that coexistence is partially based on differential water use patterns.