Acute stress-related changes in eating in the absence of hunger

Obesity results from chronic deregulation of energy balance, which may in part be caused by stress. Our objective was to investigate the effect of acute and psychological stress on food intake, using the eating in the absence of hunger paradigm, in normal and overweight men and women (while taking dietary restraint and disinhibition into account). In 129 subjects (BMI = 24.5 +/- 3.4 kg/m(2) and age = 27.6 +/- 8.8 years), scores were determined on the Three Factor Eating Questionnaire (dietary restraint = 7.2 +/- 4.4; disinhibition = 4.5 +/- 2.6; feeling of hunger = 3.9 +/- 2.6) and State-Trait Anxiety Inventory (trait score = 31.7 +/- 24.2). In a randomized crossover design, the "eating in absence of hunger" protocol was measured as a function of acute stress vs. a control task and of state anxiety scores. Energy intake from sweet foods (708.1 kJ vs. 599.4 kJ, P < 0.03) and total energy intake (965.2 kJ vs. 793.8 kJ, P < 0.01) were significantly higher in the stress condition compared to the control condition. Differences in energy intake between the stress and control condition were a function of increase in state anxiety scores during the stress task (Delta state anxiety scores) (R(2) = 0.05, P < 0.01). This positive relationship was stronger in subjects with high disinhibition scores (R(2) = 0.12, P < 0.05). Differences in state anxiety scores were a function of trait anxiety scores (R(2) = 0.07, P < 0.05). We conclude that acute psychological stress is associated with eating in the absence of hunger, especially in vulnerable individuals characterized by disinhibited eating behavior and sensitivity to chronic stress.     

A twin study of dietary restraint, disinhibition and hunger: an examination of the eating inventory (three factor eating questionnaire).

The Eating Inventory (EI) is commonly used to measure a range of eating behaviors. It includes three subscales: Cognitive Restraint, Hunger, and Disinhibition. In this study, we decomposed the variance of the three subscales, and evaluated the genetic, common environment and specific environmental effects on each in a sample of female-female twin pairs. Multivariate models were also used to examine whether the EI represented three individual factors, or whether there was extensive covariance among subscales. Heritabilities were estimated at 45% (CI of 32-57%) for Disinhibition, 8% (CI of 0-38%) for Hunger, and 0% (CI of 0-30%) for Restraint. Common environmental influences were estimated at 0% (CI of 0-23%) for Disinhibition, 16% (CI of 0-34%) for Hunger, and 31% (4-42%) for Restraint. Specific environmental influences accounted for the rest of the variance of the subscales. However, multivariate modeling indicated that Disinhibition and Hunger covaried significantly, indicating that these two subscales are influenced by the same set of genetic factors. Furthermore, Restraint appeared to be empirically distinct from Hunger or Disinhibition.     

Review and Meta‐analysis of Pharmacotherapy for Binge‐eating Disorder

This study evaluated available controlled treatment studies to determine utility of pharmacotherapy for binge‐eating disorder (BED). The authors identified randomized placebo‐controlled trials testing pharmacotherapy‐only treatments and controlled trials testing pharmacotherapy with psychotherapy treatments. Meta‐analysis was performed on placebo‐controlled trials with data for attrition, remission, and weight loss. Qualitative review was performed on remaining controlled treatment literature. A total of 33 studies were considered of which 14 studies with a total of 1,279 patients were included in the meta‐analysis of pharmacotherapy‐only treatment and 8 studies with a total of 683 patients were included in the qualitative review of pharmacotherapy combined with psychotherapy interventions. No evidence suggested significant differences between medication and placebo for attrition. Evidence suggested that pharmacological treatments have a clinically significant advantage over placebo for achieving short‐term remission from binge eating (48.7% vs. 28.5%) and for weight loss, although weight losses are not substantial. No data exist to allow evaluation of longer‐term effects of pharmacotherapy‐only treatment for BED. Combining medications with psychotherapy interventions failed to significantly enhance binge outcomes, although specific medications (orlistat, topiramate) enhanced weight losses achieved with cognitive behavioral therapy and behavioral weight loss. In summary, BED patients can be advised that certain pharmacotherapies may enhance likelihood of stopping binge eating short term, but that longer‐term effects are unknown. Although some weight loss may occur, it is unlikely to be substantial with available medications. Combining medications with cognitive or behavioral treatments is unlikely to enhance binge outcomes, but specific medications (orlistat, topiramate) may enhance weight losses, albeit modestly.     

Microbial population dynamics in the faeces of wood‐eating loricariid catfishes

Catfishes of the genus Panaque are known for their ability to feed on wood and hence to process cellulose fibres in their digestive systems. The paper industry uses cellulose fibres and thus has an interest in exploiting this property biomimetically: it could be employed as a pretreatment to lessen the energy required by the mechanical production stage of manufacturing nanocellulose fibres. Here, we characterize the diet‐associated in situ microbial diversity and population dynamic in the faeces of catfish (Panaque sp.) exposed to consecutive diets of pellet food and then wood. Fish faeces samples were collected and investigated by parallel DNA deep amplicon sequencing of the bacterial 16S rRNA SSU for both diet conditions. The most frequently occurring bacterium in the faeces was Cetobacterium sp. The dominant cellulolytic bacterial genera found in ascending relative abundance were as follows: Aeromonas sp., Flavobacterium sp., Bacteroides sp., Pseudomonas sp. and Cellvibrio sp. Diet‐associated changes in the faeces microbiome were noted for Flavobacterium sp. Extensive microbial diversity was found in catfish faeces, evidenced using culture‐independent molecular techniques. No significant diet‐associated effects on the microbiome in terms of biodiversity were observed in the catfish faeces, but diet‐associated changes in the microbial population structure were observed.

Significance and Impact of the Study

Although catfishes are not classified as true xylivores, inhabiting their faeces are bacteria that may provide a novel source of cellulolytic enzyme. Based on this first microbiology study, the faeces and thus the gastrointestinal microbiome of Panaque catfishes are an unexplored reservoir of microbial extracts with enhanced polysaccharide transforming enzyme activity. The biomimetical exploitation of this cellulolytic activity in the form of novel enzymes or by applying a mixture of cellulolytic micro‐organisms could accomplish a pretreatment to the mechanical production process of nanocellulose fibres, thus could reduce the energy consumption costs significantly.     

Caspase signalling in the absence of apoptosis drives Jnk‐dependent invasion

Tumours evolve several mechanisms to evade apoptosis, yet many resected carcinomas show significantly elevated caspase activity. Moreover, caspase activity is positively correlated with tumour aggression and adverse patient outcome. These observations indicate that caspases might have a functional role in promoting tumour invasion and metastasis. Using a Drosophila model of invasion, we show that precise effector caspase activity drives cell invasion without initiating apoptosis. Affected cells express the matrix metalloprotinase Mmp1 and invade by activating Jnk. Our results link Jnk and effector caspase signalling during the invasive process and suggest that tumours under apoptotic stresses from treatment, immune surveillance or intrinsic signals might be induced further along the metastatic cascade.     

Characterization of microsatellite loci in the Jamaican fruit‐eating bat Artibeus jamaicensis and cross‐species amplification

Artibeus jamaicensis is one of the most common bat species in the neotropics, with a well‐defined polygynous social structure in caves. In order to study behaviour and to examine patterns of paternity and relatedness between different harem groups, we developed 14 microsatellite loci from two different enriched genomic libraries. We screened 125 individuals from two different bat colonies and found that polymorphism ranged from five to 13 alleles. Heterozygosity ranged from 63 to 95%. The primers amplified across 14 bat species, indicating their potential utility for population‐level studies in several closely related bat species.     

Larvae of the coral eating crown‐of‐thorns starfish,Acanthaster planci in a warmer‐high CO2 ocean

Outbreaks of crown‐of‐thorns starfish (COTS), Acanthaster planci, contribute to major declines of coral reef ecosystems throughout the Indo‐Pacific. As the oceans warm and decrease in pH due to increased anthropogenic CO₂ production_, coral reefs are also susceptible to bleaching, disease and reduced calcification. The impacts of ocean acidification and warming may be exacerbated by COTS predation, but it is not known how this major predator will fare in a changing ocean. Because larval success is a key driver of population outbreaks, we investigated the sensitivities of larval A. planci to increased temperature (2–4 °C above ambient) and acidification (0.3–0.5 pH units below ambient) in flow‐through cross‐factorial experiments (3 temperature × 3 pH/pCO₂ levels). There was no effect of increased temperature or acidification on fertilization or very early development. Larvae reared in the optimal temperature (28 °C) were the largest across all pH treatments. Development to advanced larva was negatively affected by the high temperature treatment (30 °C) and by both experimental pH levels (pH 7.6, 7.8). Thus, planktonic life stages of A. planci may be negatively impacted by near‐future global change. Increased temperature and reduced pH had an additive negative effect on reducing larval size. The 30 °C treatment exceeded larval tolerance regardless of pH. As 30 °C sea surface temperatures may become the norm in low latitude tropical regions, poleward migration of A. planci may be expected as they follow optimal isotherms. In the absence of acclimation or adaptation, declines in low latitude populations may occur. Poleward migration will be facilitated by strong western boundary currents, with possible negative flow‐on effects on high latitude coral reefs. The contrasting responses of the larvae of A. planci and those of its coral prey to ocean acidification and warming are considered in context with potential future change in tropical reef ecosystems.     

The influence of hunger on food‐stocking behaviour of climbing perch Anabas testudineus

The present study demonstrated that the climbing perch Anabas testudineus collected and stocked food pellets in its mouth, a behaviour that has not yet been reported in any other species of fish. In this species, food deprivation for 24 h increased food stocking, but not food intake.     

Can seed‐eating birds exert top‐down effects on grasses of the Monte desert?

Granivorous animals can exert major effects on the abundance and diversity of plants when they are selective as well as efficient consumers. However, even under such conditions granivore impact will ultimately depend on whether environmental stress obscures plant-animal interactions. We studied diet and seed selection patterns of seed-eating birds to corroborate whether they are selective consumers in the central Monte desert of Argentina. Overall, 83% of seeds in bird stomachs were grass seeds, whereas only 30% of available seeds were from grass species. Therefore, we conclude that avian granivory is highly selective. We developed a set of a priori expectations to test whether birds are efficient consumers (i.e. whether they reduce seed reserves significantly), through short-term mechanism-explicit enclosure experiments. Birds decreased the number of selected grass seeds by >50%, and also reduced the amount of non-selected grasses and selected forbs when selected grass seeds were scarce in the habitat. Thus, consumption was context-dependent, varying with the composition of background seed reserves. The corroboration of foraging plasticity through mechanism-explicit trials seems to be crucial to correctly assign direct and indirect effects of seed predation in long-term enclosure experiments. The comparison of average grass seed reduction caused by bird predation with mean declines of grass seedlings caused by senescence (ca 95%) allowed us assess top-down (e.g. seed availability) vs bottom-up control (e.g. rainfall) on grass recruitment. Despite moderate to high seed predation, the number of grass seeds that remains in the soil in spring would not limit seed germination and seedling recruitment. By contrast, safe-site availability and drought may be important factors limiting grass recruitment, at least in the undisturbed habitats of the Biosphere Reserve of Ñacuñán.     

Testing the phenotype‐linked fertility hypothesis in the presence and absence of inbreeding

The phenotype‐linked fertility hypothesis suggests that females can judge male fertility by inspecting male phenotypic traits. This is because male sexually selected traits might correlate with sperm quality if both are sensitive to factors that influence male condition. A recent meta‐analysis found little support for this hypothesis, suggesting little or no shared condition dependence. However, we recently reported that in captive zebra finches (Taeniopygia guttata) inbreeding had detrimental effects both on phenotypic traits and on measures of sperm quality, implying that variation in inbreeding could induce positive covariance between indicator traits and sperm quality. Therefore, we here assess empirically the average strength of correlations between phenotypic traits (courtship rate, beak colour, tarsus length) and measures of sperm quality (proportion of functional sperm, sperm velocity, sperm length) in populations of only outbred individuals and in mixed populations consisting of inbreds (F = 0.25) and outbreds (F = 0). As expected, phenotype sperm‐trait correlations were stronger when the population contained a mix of inbred and outbred individuals. We also found unexpected heterogeneity between our two study populations, with correlations being considerably stronger in a domesticated population than in a recently wild‐derived population. Correlations ranged from essentially zero among outbred‐only wild‐derived birds (mean Fisher's Zr ± SE = 0.03 ± 0.10) to moderately strong among domesticated birds of mixed inbreeding status (Zr ± SE = 0.38 ± 0.08). Our results suggest that, under some conditions, the phenotype‐linked fertility hypothesis might apply.     

CD19 and BAFF‐R can signal to promote B‐cell survival in the absence of Syk

The development and function of B lymphocytes is regulated by numerous signaling pathways, some emanating from the B‐cell antigen receptor (BCR). The spleen tyrosine kinase (Syk) plays a central role in the activation of the BCR, but less is known about its contribution to the survival and maintenance of mature B cells. We generated mice with an inducible and B‐cell‐specific deletion of the Syk gene and found that a considerable fraction of mature Syk‐negative B cells can survive in the periphery for an extended time. Syk‐negative B cells are defective in BCR, RP105 and CD38 signaling but still respond to an IL‐4, anti‐CD40, CpG or LPS stimulus. Our in vivo experiments show that Syk‐deficient B cells require BAFF receptor and CD19/PI3K signaling for their long‐term survival. These studies also shed a new light on the signals regulating the maintenance of the normal mature murine B‐cell pool.     

Selection of sporophytic and gametophytic self‐incompatibility in the absence of a superlocus

Self‐incompatibility (SI) is a complex trait that enforces outcrossing in plant populations. SI generally involves tight linkage of genes coding for the proteins that underlie self‐pollen detection and pollen identity specification. Here, we develop two‐locus genetic models to address the question of whether sporophytic SI (SSI) and gametophytic SI (GSI) can invade populations of self‐compatible plants when there is no linkage or weak linkage of the underlying pollen detection and identity genes (i.e., no S‐locus supergene). The models assume that SI evolves as a result of exaptation of genes formerly involved in functions other than SI. Model analysis reveals that SSI and GSI can invade populations even when the underlying genes are loosely linked, provided that inbreeding depression and selfing rate are sufficiently high. Reducing recombination between these genes makes conditions for invasion more lenient. These results can help account for multiple, independent evolution of SI systems as seems to have occurred in the angiosperms.     

Parental defence on the reef: antipredator tactics of coral‐reef fishes against egg‐eating seasnakes

On coral reefs in New Caledonia, the eggs of demersal‐spawning fishes are consumed by turtle‐headed seasnakes (Emydocephalus annulatus). Fish repel nest‐raiding snakes by a series of tactics. We recorded 232 cases (involving 22 fish species) of antipredator behaviour towards snakes on a reef near Noumea. Blennies and gobies focused their attacks on snakes entering their nests, whereas damselfish (Pomacentridae) attacked passing snakes, as well as nest‐raiders (reflecting territorial defence). Biting the snake was the most common form of attack, although damselfish and blennies also slapped snakes with the tail, or (blennies only) plugged the nest entrance with the parent fish's body. Gobies rarely defended the nest, although they sometimes bit or threw sand at the snake. A snake was more likely to flee if it was attacked before it began feeding rather than after it found the eggs (82% versus 3% repelled) and if bitten on the head rather than the body (68% versus 53%). Tail‐slaps were not effective, although plugging the burrow and throwing sand often caused snakes to flee. These strong patterns reflect phylogenetic variation in fish behaviour (e.g. damselfish detect a snake approach sooner than do substrate‐dwelling blennies and gobies) coupled with intraspecific variation in snake diets. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 415–425.