MTII attenuates ghrelin- and food deprivation-induced increases in food hoarding and food intake

Food deprivation triggers a constellation of physiological and behavioral changes including increases in peripherally-produced ghrelin and centrally-produced agouti-related protein (AgRP). Upon refeeding, food intake is increased in most species, however hamsters primarily increase food hoarding. Food deprivation-induced increases in food hoarding by Siberian hamsters are mimicked by peripheral ghrelin and central AgRP injections. Because food deprivation stimulates ghrelin as well as AgRP synthesis/release, food deprivation-induced increases in hoarding may be mediated by melanocortin 3 or 4 receptor (MC3/4-R) antagonism via AgRP, the MC3/4-R inverse agonist. Therefore, we asked: Can a MC3/4-R agonist block food deprivation- or ghrelin-induced increases in foraging, food hoarding and food intake? This was accomplished by injecting melanotan II (MTII), a synthetic MC3/4-R agonist, into the 3rd ventricle in food deprived, fed or peripheral ghrelin injected hamsters and housed in a running wheel-based food delivery foraging system. Three foraging conditions were used: a) no running wheel access, non-contingent food, b) running wheel access, non-contingent food or c) a foraging requirement for food (10 revolutions/pellet). Food deprivation was a more potent stimulator of foraging and hoarding than ghrelin. Concurrent injections of MTII completely blocked food deprivation- and ghrelin-induced increases in food intake and attenuated, but did not always completely block, food deprivation- and ghrelin-induced increases in food hoarding. Collectively, these data suggest that the MC3/4-R are involved in ghrelin- and food deprivation-induced increases in food intake, but other neurochemical systems, such as previously demonstrated with neuropeptide Y, also are involved in increases in food hoarding as well as foraging.     

MTII attenuates ghrelin- and food deprivation-induced increases in food hoarding and food intake

Food deprivation triggers a constellation of physiological and behavioral changes including increases in peripherally-produced ghrelin and centrally-produced agouti-related protein (AgRP). Upon refeeding, food intake is increased in most species, however hamsters primarily increase food hoarding. Food deprivation-induced increases in food hoarding by Siberian hamsters are mimicked by peripheral ghrelin and central AgRP injections. Because food deprivation stimulates ghrelin as well as AgRP synthesis/release, food deprivation-induced increases in hoarding may be mediated by melanocortin 3 or 4 receptor (MC3/4-R) antagonism via AgRP, the MC3/4-R inverse agonist. Therefore, we asked: Can a MC3/4-R agonist block food deprivation- or ghrelin-induced increases in foraging, food hoarding and food intake? This was accomplished by injecting melanotan II (MTII), a synthetic MC3/4-R agonist, into the 3rd ventricle in food deprived, fed or peripheral ghrelin injected hamsters and housed in a running wheel-based food delivery foraging system. Three foraging conditions were used: a) no running wheel access, non-contingent food, b) running wheel access, non-contingent food or c) a foraging requirement for food (10 revolutions/pellet). Food deprivation was a more potent stimulator of foraging and hoarding than ghrelin. Concurrent injections of MTII completely blocked food deprivation- and ghrelin-induced increases in food intake and attenuated, but did not always completely block, food deprivation- and ghrelin-induced increases in food hoarding. Collectively, these data suggest that the MC3/4-R are involved in ghrelin- and food deprivation-induced increases in food intake, but other neurochemical systems, such as previously demonstrated with neuropeptide Y, also are involved in increases in food hoarding as well as foraging.     

Maternal Food Regurgitation to Nymphs in Earwigs (Forficula auricularia)

The occurrence of parental food regurgitation as a form of parental care in (sub-) social insects has been little studied and is largely based on anectodal and indirect evidence. However, understanding the behavioural mechanisms mediating the benefit of parental care is critical to advance research on the evolution of family interactions. Here, we report results from a study where we experimentally tested the hypothesis that European earwig ( Forficula auricularia ) females regurgitate food to their nymphs. We used a simple experimental method based on food dyes as colour markers to separate maternal food regurgitation and nymphal self-feeding as the two components of food intake by nymphs. Two different food dyes were used to label the food offered to the earwig mother and the nymphs respectively. By analysing the colour of the gut content of the nymphs, we demonstrate significant food transfer from the mother to the nymphs. This study demonstrates unambiguously that maternal food regurgitation exists in earwigs and presents a simple and easily applicable technique to trace maternal food regurgitation in the study of insect parental care and family interactions.     

High-pressure processing – effects on microbial food safety and food quality

High-pressure processing (HPP) is a nonthermal process capable of inactivating and eliminating pathogenic and food spoilage microorganisms. This novel technology has enormous potential in the food industry, controlling food spoilage, improving food safety and extending product shelf life while retaining the characteristics of fresh, preservative-free, minimally processed foods. As with other food processing methods, such as thermal processing, HPP has somewhat limited applications as it cannot be universally applied to all food types, such as some dairy and animal products and shelf-stable low-acid foods. Herein, we discuss the effects of high-pressure processing on microbial food safety and, to a lesser degree, food quality.     

Maintenance of delay of gratification by four chimpanzees (Pan troglodytes): the effects of delayed reward visibility, experimenter presence, and extended delay intervals

Previous research in our laboratory has demonstrated that chimpanzees can delay gratification by inhibiting consumption of available food items for as long as 3 min as an experimenter transfers additional food items from a transparent container to a bowl placed in front of the subject. In this study, we examined the influence of the visibility of the food source, as well as the presence of the experimenter, on four chimpanzees' self-control in this paradigm. In Experiment 1 an experimenter transferred 15 preferred food items between a distant opaque container and a bowl placed in front of the subject. In Experiment 2 we tested the chimpanzees with an automated system that (in the absence of the experimenter) transferred up to 36 highly preferred food items from a universal food dispenser to a container located either inside or outside of the subject's enclosure. There were no differences in self-directed behaviors or attentiveness to the food items between the self-imposed and externally imposed delay conditions. A final experiment with the automated paradigm indicated that individuals could delay gratification for up to 11min in order to obtain all 36 food items.     

Climate change and food security

Dynamic interactions between and within the biogeophysical and human environments lead to the production, processing, distribution, preparation and consumption of food, resulting in food systems that underpin food security. Food systems encompass food availability (production, distribution and exchange), food access (affordability, allocation and preference) and food utilization (nutritional and societal values and safety), so that food security is, therefore, diminished when food systems are stressed. Such stresses may be induced by a range of factors in addition to climate change and/or other agents of environmental change (e.g. conflict, HIV/AIDS) and may be particularly severe when these factors act in combination. Urbanization and globalization are causing rapid changes to food systems. Climate change may affect food systems in several ways ranging from direct effects on crop production (e.g. changes in rainfall leading to drought or flooding, or warmer or cooler temperatures leading to changes in the length of growing season), to changes in markets, food prices and supply chain infrastructure. The relative importance of climate change for food security differs between regions. For example, in southern Africa, climate is among the most frequently cited drivers of food insecurity because it acts both as an underlying, ongoing issue and as a short-lived shock. The low ability to cope with shocks and to mitigate long-term stresses means that coping strategies that might be available in other regions are unavailable or inappropriate. In other regions, though, such as parts of the Indo-Gangetic Plain of India, other drivers, such as labour issues and the availability and quality of ground water for irrigation, rank higher than the direct effects of climate change as factors influencing food security. Because of the multiple socio-economic and bio-physical factors affecting food systems and hence food security, the capacity to adapt food systems to reduce their vulnerability to climate change is not uniform. Improved systems of food production, food distribution and economic access may all contribute to food systems adapted to cope with climate change, but in adopting such changes it will be important to ensure that they contribute to sustainability. Agriculture is a major contributor of the greenhouse gases methane (CH4) and nitrous oxide (N2O), so that regionally derived policies promoting adapted food systems need to mitigate further climate change.     

Regulatory peptides and control of food intake in non-mammalian vertebrates

The current view of the control of food intake involves a central feeding system in the hypothalamus receiving input from peripheral systems. The presence of food in the gut stimulates the release of several regulatory peptides that control gut motility and secretion. Some of these peptides also act as feedback satiety signals, responsible for termination of a meal. Among the regulatory peptides suggested as peripheral satiety signals are cholecystokinin and gastrin releasing peptide. A more long-term peripheral regulation of food intake has also been postulated and leptin has been suggested as a regulator of food intake. Several regulatory peptides mediate orexigenic or anorexigenic effects in the central feeding system. Neuropeptide Y and galanin both act centrally and stimulate the intake of food, while corticotropin releasing factor reduces food intake. At present, most information about the regulation of food intake is gained from mammalian studies and these findings are used as a base for a discussion on the current knowledge of how regulatory peptides control appetite in non-mammalian vertebrates.     

Seasonal variation in the diet of citril finches <Emphasis Type="Italic">Carduelis citrinella</Emphasis>: are they specialists or generalists?

The seasonal variation of food selection in mountainous citril finches was studied in the Black Forest. citril finches show a strong seasonal variation in quantity and quality of food plants. From November to March, only a few plants have been observed as diet, namely seeds of the germander and the mountain pine (period of food restriction). From April to June, the seeds of a few key food plants such as the dandelion, common sorrel, vernal grass, and mountain pine gain special importance during breeding and the rearing period of the young (period of food specialization). Finally, from June/July to October, citril finches enter into a generalist period with a wide variety of seeds of herbs and grasses (period of food generalization). The changes in food selection are well adapted to the changing resource availabilities and climatic conditions of the Black Forest mountains. In direct comparison to other finches, pure mountain-dwelling species such as citril finches and Syrian serins show a clearly higher seasonal variability in food selection than do lowland species such as goldfinches, linnets, and greenfinches.     

All you can eat: is food supply unlimited in a colonially breeding bird?

Food availability is generally considered to determine breeding site selection and therefore plays an important role in hypotheses explaining the evolution of colony formation. Hypotheses trying to explain why birds join a colony usually assume that food is not limited, whereas those explaining variation in colony size suggest that food is under constraint. In this study, we investigate the composition and amount of food items not eaten by the nestlings and found in nest burrows of colonially nesting European bee‐eaters (Merops apiaster). We aimed to determine whether this unconsumed food is an indicator of unlimited food supply, the result of mistakes during food transfer between parents and chicks or foraging selectivity of chicks. Therefore, we investigated the amount of dropped food for each nest in relation to reproductive performance and parameters reflecting parental quality. Our data suggest that parents carry more food to the nest than chicks can eat and, hence, food is not limited. This assumption is supported by the facts that there is a positive relationship between dropped food found in a nest and the number of fledglings, nestling age, and chick health condition and that the amount of dropped food is independent of colony size. There is variation in the amount of dropped food within colonies, suggesting that parent foraging efficiency may also be an important determinant. Pairs nesting in the center of a colony performed better than those nesting on the edge, which supports the assumption that quality differences between parents are important as well. However, dropped food cannot be used as an indicator of local food availability as (1) within‐colony variation in dropped food is larger than between colony variation and, (2) the average amount of dropped food is not related to colony size.     

Short- and long-term effects of environmental urea on fecundity inDrosophila melanogaster

Previous studies have shown that exposure to urea-supplemented food inhibited fecundity inDrosophila females, and that this inhibition was not expressed when females were given a choice between regular and urea-supplemented food as an oviposition substrate. We assayed fecundity, on both regular food and urea-supplemented food, at 5, 15 and 25 days post eclosion on females from ten laboratory populations ofDrosophila melanogaster. The females assayed came from one of two treatments; they were maintained as adults on either regular or urea-supplemented food. We found that exposure to urea-supplemented food inhibited fecundity, relative to the levels exhibited on regular food, regardless of whether the urea was present in the assay medium, or in the medium on which the flies were maintained over the course of the experiment, thereby suggesting that urea has both a long-term (possibly physiological) as well as a short-term (possibly behavioural) inhibitory effect on fecundity ofDrosophila females. We also tested and ruled out the hypothesis that prior yeasting could ameliorate the inhibitory effect of urea in the assay medium on fecundity, as this was a possible explanation of why flies given a choice between regular and urea-supplemented food did not exhibit a preference for regular food in a previous study.     

Food sensory characteristics: their unconsidered roles in the feeding behaviour of domestic ruminants

When domestic ruminants are faced with food diversity, they can use pre-ingestive information (i.e. food sensory characteristics perceived by the animal before swallowing the food) and post-ingestive information (i.e. digestive and metabolic consequences, experienced by the animal after swallowing the food) to evaluate the food and make decisions to select a suitable diet. The concept of palatability is essential to understand how pre- and post-ingestive information are interrelated. It refers to the hedonic value of the food without any immediate effect of post-ingestive consequences and environmental factors, but with the influence of individual characteristics, such as animal's genetic background, internal state and previous experiences. In the literature, the post-ingestive consequences are commonly considered as the main force that influences feeding behaviour whereas food sensory characteristics are only used as discriminatory agents. This discriminatory role is indeed important for animals to be aware of their feeding environment, and ruminants are able to use their different senses either singly or in combination to discriminate between different foods. However, numerous studies on ruminants’ feeding behaviour demonstrate that the role of food sensory characteristics has been underestimated or simplified; they could play at least two other roles. First, some sensory characteristics also possess a hedonic value which influences ruminants’ intake, preferences and food learning independently of any immediate post-ingestive consequences. Further, diversity of food sensory characteristics has a hedonic value, as animals prefer an absence of monotony in food sensory characteristics at similar post-ingestive consequences. Second, some of these food sensory characteristics become an indicator of post-ingestive consequences after their initial hedonic value has acquired a positive or a negative value via previous individual food learning or evolutionary processes. These food sensory characteristics thus represent cues that could help ruminants to anticipate the post-ingestive consequences of a food and to improve their learning efficiency, especially in complex environments. This review then suggests that food sensory characteristics could be of importance to provide pleasure to animals, to increase palatability of a food and to help them learn in complex feeding situations which could improve animal welfare and productivity.     

Trophallaxis in <Emphasis Type="Italic">Lasius niger</Emphasis>: a variable frequency and constant duration for three food types

While food recruitment and foraging have been the subject of many studies, the regulation of the food sharing behaviour remains poorly understood. In this study, we focused on trophallaxis (or mouth-to-mouth food exchange) within a group of worker ants as the first step in characterizing food sharing behaviours. In particular, we wanted to investigate the influence of the type of the food on trophallaxis. We studied three food types: a 1 M sucrose solution, a solution rich in proteins and a 1 M solution of melezitose, the latter being referred to as the ants’ favourite sugar. Our results show that the type of the food influences the frequency of trophallaxis but not the duration of each food exchange. Indeed, the total number of trophallaxes differed with the type of food, whereas the duration of trophallaxis was similar regardless of the food exchanged. Furthermore, the probability of stopping an exchange per unit of time was constant and did not depend on the time the exchange had already lasted. This suggests that food distribution is principally regulated by the frequency of trophallaxis rather than the amount of food exchanged and brings new questions about the regulation of food flow between individuals.     

Meal sharing among the Ye’kwana

In this study meal sharing is used as a way of quantifying food transfers between households. Traditional food-sharing studies measure the flow of resources between households. Meal sharing, in contrast, measures food consumption acts according to whether one is a host or a guest in the household as well as the movement of people between households in the context of food consumption. Our goal is to test a number of evolutionary models of food transfers, but first we argue that before one tests models of who should receive food one must understand the adaptiveness of food transfers. For the Ye’kwana, economies of scale in food processing and preparation appear to set the stage for the utility of meal sharing. Evolutionary models of meal sharing, such as kin selection and reciprocal altruism, are evaluated along with non-evolutionary models, such as egalitarian exchange and residential propinquity. In addition, a modified measure of exchange balance—proportional balance—is developed. Reciprocal altruism is shown to be the strongest predictor of exchange intensity and balance.     

灵长类动物的食物分享行为

食物分享是灵长类动物的一种重要社会交往行为,主要发生在成体-幼体间和成体-成体之间。本文从这两个方面对灵长类动物食物分享的行为表现、特点以及功能进行总结,着重比较了无亲缘关系的成年个体间食物分享的互惠解释和骚扰解释。通过对以上内容的综合分析,进一步提出了食物分享行为的未来研究方向以及对人类合作行为演化的启示。     

Social patterns of food sharing in monogamous owl monkeys

Captive owl monkeys (Aotus nancymaae, A. azarai) share food frequently within both families and pairs. In this study food sharing was observed in seven mated pairs and four families (i.e., four mated pairs and their offspring). Patterns of food sharing were examined with respect to age class, sex, and the presence or absence of dependent offspring. Within families, most food transfers were from adult males to developing offspring. Adult males and females transferred food to their mates in caged pairs as well as in family units. Food interactions between adults are as likely to result in food transfers as those between adults and offspring. This pattern of food sharing between mates in a monogamous species may serve both nutritional and social functions that differ from those in polygamous species.     

Diet of the gracile mouse opossum (Gracilinanus microtarsus) (Didelphimorphia: Didelphidae) in a Brazilian cerrado: patterns of food consumption and intrapopulation variation

The diet of the gracile mouse opossum Gracilinanus microtarsus was studied in a cerrado remnant in south-eastern Brazil through the analysis of faeces sampled from adult individuals. Patterns of food resource consumption were assessed using the statistics of per cent occurrence. Intrapopulation variation in the number of food items detected in faeces as a function of relevant factors was inferred using generalized linear models. The latter statistical formalism also allowed variation in the number of food items detected in faeces to be interpreted in terms of rate ratios among levels of significant factors. Insects, spiders, snails and fruits were detected in the faeces of G. microtarsus , with insects, particularly termites, beetles and ants, being the most frequently detected food resource. These food resources were consumed in proportion to their relative abundance in the cerrado, suggesting that G . microtarsus is an opportunistic forager feeding primarily on insects. The generalized linear model identified sex, season and food resource as significant factors affecting the number of food items detected in faeces, as well as interactions between sex and season and season and food resource. Rate ratios calculated between sexes within seasons showed that the number of food items detected in the faeces of males was larger than that detected in the faeces of females in the warm-wet and cool-dry seasons. Rate ratios calculated between seasons within sexes showed different trends in the number of food items detected in faeces for each significant food resource. It is suggested that differences in the number of food items detected in faeces between sexes within season and between seasons within sexes are related to energetic requirements associated with reproduction.     

Potential of Biowaste from the Food Industry as a Biomass Resource

The importance of biomass as a resource for energy production or as a chemical feedstock will increase significantly in the next decades. The amounts of biomass that can be used for non‐food purposes however will be limited and its use will compete with other claims like food and feed production. In order to minimize such food‐feed‐fuel conflicts it is necessary to integrate all kinds of biowaste into a biomass economy. The food industry in particular might be a good candidate for assessment, since it produces inevitably large amounts of biogenic residues each year. The possibilities to use food processing residues for non‐food purposes like bioenergy, biomaterial production, chemical feedstock or as animal feed are therefore discussed in more detail in this paper. It is shown that food processing residues represent a small but valuable biomass fraction that can be exploited in numerous ways. The most promising approach appears to be to design new microbial bioconversion processes as part of more complex biorefinery concepts.     

Social interaction with non-averse group-mates modifies a learned food aversion in single- and mixed-species groups of tamarins (Saguinus fuscicollis and S. labiatus)

For social species, being a member of a cohesive group and performing activities as a coordinated unit appear to provide a mechanism for the efficient transmission of information about food. Social learning about food palatability was investigated in two captive primates, Saguinus fuscicollis and S. labiatus, which form stable and cohesive mixed-species groups in the wild. We explored whether an induced food aversion toward a preferred food is modified during and after social interaction with non-averse conspecifics or congeners. Sets of intra- and interspecific pairs were presented with two foods, one of which was considered distasteful by one of the pairs (the other was palatable), and their behavior was compared pre-interaction, during interaction, and post-interaction. For the aversely-conditioned individuals of both species, the change in social context corresponded to a change in their preference for the food that they considered unpalatable, regardless of whether they had interacted with a conspecific or congeneric pair, and the change in food preference was maintained post-interaction. In a control condition, in which averse individuals did not have the opportunity to interact with non-averse animals, S. fuscicollis sampled the preferred food, but not as quickly as when given the opportunity to interact. We conclude that the social learning demonstrated here may allow individual tamarins to track environmental change, such as fruit ripening, more efficiently than asocial learning alone, because social learners can more quickly and safely focus on appropriate behavior by sharing up-to-date foraging information. Furthermore, since the behavior of congeners, as well as conspecifics, acts to influence food choice in a more adaptive direction, social learning about food palatability may be an advantage of mixed-species group formation to tamarins of both species.     

Ontogeny of social behaviour related to feeding in the Crab-eating fox (Cerdocyon thous) and the Bush dog (Speothos venaticus)

This study examines the development of social interactions involved in food apportionment in two captive parent-raised litters of Crab-eating foxes ( Cerdocyon thous ) and three of Bush dogs ( Speothos venaticus ), by presentation of live prey items and a regular food ration. Cerdocyon pups are initially very aggressive over food but, with experience, gradually develop the adult pattern of respecting ownership of food, without determining access by means of a dominance hierarchy. Adults mediate food transfers between pups and facilitate the learning process as well as the distribution of food resources.
Speothos pups never fight over or defend food and show no important ontogenetic changes in response to feeding situations.