Social learning directs feeding preferences in the zebra finch, Taeniopygia guttata

We tested sexually mature zebra finches to see whether social learning influenced their feeding preferences, in particular whether they followed the preference of a male or a female demonstrator, of a red-ringed or a green-ringed male, and of a familiar or an unfamiliar male. Each observer was exposed to two demonstrators feeding at different-coloured hoppers, and then tested with a choice of hoppers to see which of the two colours they preferred. Males showed no preference between male and female demonstrators when choosing from which colour of food hopper to feed, but females preferred to feed from the hopper colour the male demonstrator had used. Both males and females exposed to male demonstrators wearing red or green leg rings fed preferentially from the same colour hopper as the red-ringed demonstrators had used. Finally, male birds exposed to familiar and unfamiliar demonstrators, preferred the food hopper from which the familiar demonstrator had fed. We interpret the results as indicating differences between the demonstrators in the amount of attention they attracted from observers.Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

A Feeding Induced Switch from a Variable to a Homogenous State of the Earthworm Gut Microbiota within a Host Population

Background

The distribution pattern of the earthworm gut microbiota at the host population level is of fundamental importance to understand host-microbiota interactions. Our current understanding of these interactions is very limited. Since feeding represents a main perturbation of the gut microbiota, we determined the effect of a single dose of feed on the microbiota associated with an earthworm population in a simulated microenvironment.

Methodology

Earthworms were sampled 0, 1 and 7 days after feeding. We determined the overall composition of the earthworm-associated microbiota by 16S rRNA gene cloning and sequencing. Based on the 16S rRNA gene data we constructed quantitative PCR''s (Q-PCR) for the seven most dominating bacterial groups.

Principal Findings

Q-PCR revealed low density and highly variable microbiota among the earthworms before feeding, while a high-density homologous microbiota resulted from feeding. We found that the microbiota 1 day after feeding was more equal to the microbiota after 7 days than before feeding. Furthermore, we found that the gut microbiota was very distinct from that of the bedding and the feed.

Significance

The homogenous population response represents fundamental new knowledge about earthworm gut associated bacteria.     

Socially biased learning among adult cottontop tamarins (Saguinus oedipus)

We presented adult cottontop tamarins (Saguinus oedipus) with a novel foraging task that had been used previously to examine socially biased learning of juvenile observers [Humle & Snowdon, Animal Behaviour 75:267–277, 2008]. The task could be solved in one of two ways, and thus allowed for an analysis of behavioral matching between an observer and a skilled demonstrator (trained to use one of the two methods exclusively). Because the demonstrator was an adult in both this study and the juvenile study, the influence of the observer's age could be isolated and examined, as well as the behavior of demonstrators toward observers of different ages. Our main goals were to (1) compare adults and juveniles acquiring the same task to identify how the age of the observer affects socially biased learning and (2) examine the relationship between socially biased learning and behavioral matching in adults. Although adults spent less time observing the trained demonstrators than did juveniles, the adults were more proficient at solving the task. Furthermore, even though observers did not overtly match the behavior of the demonstrator, observation remained an important factor in the success of these individuals. The findings suggested that adult observers could extract information needed to solve a novel foraging task without explicitly matching the behavior of the demonstrator. Adult observers begged much less than juveniles and demonstrators did not respond to begging from adult. Skill acquisition and the process of socially biased learning are, therefore, age‐dependent and are influenced by the behavioral interactions between observer and demonstrator. To what extent this holds true for other primates or animal species still needs to be more fully investigated and considered when designing experiments and interpreting results. Am. J. Primatol. 72:287–295, 2010. © 2009 Wiley‐Liss, Inc.     

Spectral detection of thalassemia: a preliminary study

Background

Thalassemias (Thal) are forms of inherited autosomal recessive blood disorders arising out of mutations in the chromosomes 11 or 16. These disorders lead to poor oxygen delivery to blood vessels and consequent splenomegaly, bone deformities, and shorter life spans. The most common detection methods for Thal are complete blood count (CBC) followed by electrophoresis and molecular diagnosis methods, such as high-performance liquid chromatography (HPLC) and polymerase chain reaction (PCR) genotyping. These methods involve sophisticated instrumentations and are cumbersome and expensive.

Results

In this study an innovative spectral detection method, based on the fluorescence spectra of a set of biomolecules (tyrosine, tryptophan, nicotinamide adenine dinucleotide, and flavin adenine dinucleotide and porphyrins) found in blood components is presented. An algorithm based on the spectral features of such biomolecules of blood components of 20 Thal patients (10 female and 10 male) and 18 age adjusted normal controls (4 female and 14 male) demonstrate reasonable level of classification with sensitivity and specificity values exceeding 90%.

Conclusion

This new technique could be of significant value for Thal detection, diagnosis, and subsequent genetic counselling and could be adapted for use in small primary health centres.     

Individual differences in responses of Norway rats to social induction of food preferences

Each of 36 observer rats was: (1) exposed to a demonstrator rat that had eaten an unpalatable, cayenne-pepper-flavored diet (Diet Cay), then tested to determine its willingness to eat Diet Cay and (2) exposed to a demonstrator rat that had eaten a palatable diet (Diet NPT) to which the observer had previously learned an aversion, then tested to determine its willingness to eat Diet NPT. In both instances, some observers ate substantial amounts of the diet that their respective demonstrators had eaten, while other observers did not. No consistency was found across the two situations in the relative susceptibility of individual observer rats to social influences on their food choices. In a second experiment, observer rats interacted, at 3 day intervals, with demonstrator rats that had each eaten different diets. After each interaction, all observers were given a choice test to determine their preferences for the diet that their demonstrators had eaten. Again, there was no consistency in the relative strength of individual observer rats' socially induced preferences for diets fed to demonstrators. Stable individual differences in magnitude of susceptibility to social influence on food preference did not account for a detectable proportion of observed variance in diet selection.     

Tactical release of a sexually-selected pheromone in a swordtail fish

Background

Chemical communication plays a critical role in sexual selection and speciation in fishes; however, it is generally assumed that most fish pheromones are passively released since most fishes lack specialized scent glands or scent-marking behavior. Swordtails (genus Xiphophorus) are widely used in studies of female mate choice, and female response to male chemical cues is important to sexual selection, reproductive isolation, and hybridization. However, it is unclear whether females are attending to passively produced cues, or to pheromones produced in the context of communication.

Methodology/Principal Findings

We used fluorescein dye injections to visualize pulsed urine release in male sheepshead swordtails, Xiphophorus birchmanni. Simultaneous-choice assays of mating preference showed that females attend to species- and sex-specific chemical cues emitted in male urine. Males urinated more frequently in the presence and proximity of an audience (conspecific females). In the wild, males preferentially courted upstream of females, facilitating transmission of pheromone cues.

Conclusions/Significance

Males in a teleost fish have evolved sophisticated temporal and spatial control of pheromone release, comparable to that found in terrestrial animals. Pheromones are released specifically in a communicative context, and the timing and positioning of release favors efficient signal transmission.     

Paternal mtDNA and Maleness Are Co-Inherited but Not Causally Linked in Mytilid Mussels

Background

In marine mussels of the genus Mytilus there are two mitochondrial genomes. One is transmitted through the female parent, which is the normal transmission route in animals, and the other is transmitted through the male parent which is an unusual phenomenon. In males the germ cell line is dominated by the paternal mitochondrial genome and the somatic cell line by the maternal. Research to date has not allowed a clear answer to the question of whether inheritance of the paternal genome is causally related to maleness.

Methodology/Principal Findings

Here we present results from hybrid crosses, from triploid mussels and from observations of sperm mitochondria in fertilized eggs which clearly show that maleness and presence of the paternal mitochondrial genome can be decoupled. These same results show that the female mussel has exclusive control of whether her progeny will inherit the mitochondrial genome of the male parent.

Conclusions/Significance

These findings are important in our efforts to understand the mechanistic basis of this unusual mode of mitochondrial DNA inheritance that is common among bivalves.     

Social Facilitation of Eating Familiar Food in Tufted Capuchins (<Emphasis Type="Italic">Cebus apella</Emphasis>): Does it Involve Behavioral Coordination?

Social facilitation of eating familiar foods might serve to synchronize eating activities within groups. We aimed to assess whether capuchins (Cebus apella) are prompted to eat when observing other conspecifics eating a familiar food. Subjects were 8 male captive-born tufted capuchins. One pair of capuchins acted as demonstrators for the other 6 observer subjects. In the Experimental condition, the demonstrator pair was given fresh chow in addition to having access to the leftover food and ate continuously. In the Control condition, the demonstrator pair had access to food leftover from the morning feed and ate very little. The initiation of feeding by the demonstrator pair prompted the initiation of feeding behavior in the observers, and the latter ate significantly more of their leftovers in the Experimental than in the Control condition. The tempo ofthe social facilitation of eating familiar foods in capuchins supportisomorphic coordination, a process that occurs when one individuals activity focuses the attention of another individual to the same activity, thereby increasing behavioral similarity in a group.     

Spread of social information and dynamics of social transmission within Drosophila groups

Understanding how behavioral diversity arises and is maintained is central to evolutionary biology. Genetically based inheritance has been a predominant research focus of the last century; however, nongenetic inheritance, such as social transmission, has become a topic of increasing interest [1]. How social information impacts behavior depends on the balance between information gathered directly through personal experience versus that gleaned through social interactions and on the diffusion of this information within groups [2, 3]. We investigate how female Drosophila melanogaster use social information under seminatural conditions and whether this information can spread and be maintained within a group, a prerequisite for establishing behavioral transmission [4]. We show that oviposition site choice is heavily influenced by previous social interactions. Naive observer flies develop a preference for the same egg-laying medium as experienced demonstrator flies conditioned to avoid one of two equally rewarding media. Surprisingly, oviposition site preference was socially transmitted from demonstrators to observers even when they interacted in a cage with only unflavored, pure agar medium, and even when the observer flies had previous personal experience with both rewarding media. Our findings shed light on the diffusion process of social information within groups, on its maintenance, and ultimately, on the roots of behavioral local adaptation.     

Visualizing Non Infectious and Infectious Anopheles gambiae Blood Feedings in Naive and Saliva-Immunized Mice

Background

Anopheles gambiae is a major vector of malaria and lymphatic filariasis. The arthropod-host interactions occurring at the skin interface are complex and dynamic. We used a global approach to describe the interaction between the mosquito (infected or uninfected) and the skin of mammals during blood feeding.

Methods

Intravital video microscopy was used to characterize several features during blood feeding. The deposition and movement of Plasmodium berghei sporozoites in the dermis were also observed. We also used histological techniques to analyze the impact of infected and uninfected feedings on the skin cell response in naive mice.

Results

The mouthparts were highly mobile within the skin during the probing phase. Probing time increased with mosquito age, with possible effects on pathogen transmission. Repletion was achieved by capillary feeding. The presence of sporozoites in the salivary glands modified the behavior of the mosquitoes, with infected females tending to probe more than uninfected females (86% versus 44%). A white area around the tip of the proboscis was observed when the mosquitoes fed on blood from the vessels of mice immunized with saliva. Mosquito feedings elicited an acute inflammatory response in naive mice that peaked three hours after the bite. Polynuclear and mast cells were associated with saliva deposits. We describe the first visualization of saliva in the skin by immunohistochemistry (IHC) with antibodies directed against saliva. Both saliva deposits and sporozoites were detected in the skin for up to 18 h after the bite.

Conclusion

This study, in which we visualized the probing and engorgement phases of Anopheles gambiae blood meals, provides precise information about the behavior of the insect as a function of its infection status and the presence or absence of anti-saliva antibodies. It also provides insight into the possible consequences of the inflammatory reaction for blood feeding and pathogen transmission.     

Percutaneous cryoablation of pulmonary metastases from colorectal cancer

Objective

To evaluate the safety and efficacy of cryoablation for metastatic lung tumors from colorectal cancer.

Methods

The procedures were performed on 24 patients (36–82 years of age, with a median age of 62; 17 male patients, 7 female patients) for 55 metastatic tumors in the lung, during 30 sessions. The procedural safety, local progression free interval, and overall survival were assessed by follow-up computed tomographic scanning performed every 3–4 months.

Results

The major complications were pneumothorax, 19 sessions (63%), pleural effusion, 21 sessions (70%), transient and self-limiting hemoptysis, 13 sessions (43%) and tract seeding, 1 session (3%). The 1- and 3-year local progression free intervals were 90.8% and 59%, respectively. The 3-years local progression free intervals of tumors ≤15 mm in diameter was 79.8% and that of tumors >15 mm was 28.6% (p = 0.001; log-rank test). The 1- and 3-year overall survival rates were 91% and 59.6%, respectively.

Conclusion

The results indicated that percutaneous cryoablation is a feasible treatment option. The local progression free interval was satisfactory at least for tumors that were ≤15 mm in diameter.     

Inheritance of fertility in broiler chickens

Background

The fertility of a chicken''s egg is a trait which depends on both the hen that lays the egg and on her mate. It is also known that fertility of an individual changes over the laying period.

Methods

Longitudinal models including both random genetic and permanent environmental effects of both the female and her male mate were used to model the proportion of fertile eggs in a pedigree broiler population over the ages 29-54 weeks.

Results

Both the male and the female contribute to variation in fertility. Estimates of heritability of weekly records were typically 7% for female and 10% for male contributions to fertility. Repeatability estimates ranged from 24 to 33%, respectively. The estimated genetic variance remained almost constant for both sexes over the laying period and the genetic correlations between different ages were close to 1.0. The permanent environment components increased substantially towards the end of the analyzed period, and correlations between permanent environment effects at different ages declined with increasing age difference The heritability of mean fertility over the whole laying period was estimated at 13% for females and 17% for males. A small positive correlation between genetic effects for male and female fertility was found.

Conclusion

Opportunities to improve fertility in broiler stocks by selection on both sexes exist and should have an impact throughout the laying period.     

The Long-Term Effects of Stress on Partner Weight Characteristics

Background

Recent experimental evidence suggests that stressed males find heavier women more attractive than non-stressed males. The aim of this study is to examine whether these results also appear in actual mating patterns of adults from a national sample.

Methods

Regression analysis linking partner weight measures to own measures of childhood stress, as measured by mistreatment. Cross-sectional data from the National Longitudinal Study of Adolescent Health, Romantic Partners Sample is used to measure partner weight, childhood stressful events, and socio-demographic characteristics. Childhood experiences of adult mistreatment are retrospectively collected.

Results

Men who experienced childhood mistreatment are more likely to have obese female partners during young adulthood. The results are strongest for interactions with social services, adult neglect and physical abuse. We also present novel evidence of the opposite association in similarly stressed women whose male partners are more likely to be thin.

Conclusions

These results suggest that preferences for partner characteristics are sensitive to histories of stress and that previously hypothesized patterns occur outside the experimental setting.     

Heterogeneous Feeding Patterns of the Dengue Vector,Aedes aegypti,on Individual Human Hosts in Rural Thailand

Background

Mosquito biting frequency and how bites are distributed among different people can have significant epidemiologic effects. An improved understanding of mosquito vector-human interactions would refine knowledge of the entomological processes supporting pathogen transmission and could reveal targets for minimizing risk and breaking pathogen transmission cycles.

Methodology and principal findings

We used human DNA blood meal profiling of the dengue virus (DENV) vector, Aedes aegypti, to quantify its contact with human hosts and to infer epidemiologic implications of its blood feeding behavior. We determined the number of different people bitten, biting frequency by host age, size, mosquito age, and the number of times each person was bitten. Of 3,677 engorged mosquitoes collected and 1,186 complete DNA profiles, only 420 meals matched people from the study area, indicating that Ae. aegypti feed on people moving transiently through communities to conduct daily business. 10–13% of engorged mosquitoes fed on more than one person. No biting rate differences were detected between high- and low-dengue transmission seasons. We estimate that 43–46% of engorged mosquitoes bit more than one person within each gonotrophic cycle. Most multiple meals were from residents of the mosquito collection house or neighbors. People ≤25 years old were bitten less often than older people. Some hosts were fed on frequently, with three hosts bitten nine times. Interaction networks for mosquitoes and humans revealed biologically significant blood feeding hotspots, including community marketplaces.

Conclusion and significance

High multiple-feeding rates and feeding on community visitors are likely important features in the efficient transmission and rapid spread of DENV. These results help explain why reducing vector populations alone is difficult for dengue prevention and support the argument for additional studies of mosquito feeding behavior, which when integrated with a greater understanding of human behavior will refine estimates of risk and strategies for dengue control.     

The endangered Iris atropurpurea (Iridaceae) in Israel: honey-bees,night-sheltering male bees and female solitary bees as pollinators

Background and Aims

The coastal plain of Israel hosts the last few remaining populations of the endemic Iris atropurpurea (Iridaceae), a Red List species of high conservation priority. The flowers offer no nectar reward. Here the role of night-sheltering male solitary bees, honey-bees and female solitary bees as pollinators of I. atropurpurea is documented.

Methods

Breeding system, floral longevity, stigma receptivity, visitation rates, pollen loads, pollen deposition and removal and fruit- and seed-set were investigated.

Key Results

The main wild pollinators of this plant are male eucerine bees, and to a lesser extent, but with the potential to transfer pollen, female solitary bees. Honey-bees were found to be frequent diurnal visitors; they removed large quantities of pollen and were as effective as male sheltering bees at pollinating this species. The low density of pollen carried by male solitary bees was attributed to grooming activities, pollen displacement when bees aggregated together in flowers and pollen depletion by honey-bees. In the population free of honey-bee hives, male bees carried significantly more pollen grains on their bodies. Results from pollen analysis and pollen deposited on stigmas suggest that inadequate pollination may be an important factor limiting fruit-set. In the presence of honey-bees, eucerine bees were low removal–low deposition pollinators, whereas honey-bees were high removal–low deposition pollinators, because they removed large amounts into corbiculae and deposited relatively little onto receptive stigmas.

Conclusions

Even though overall, both bee taxa were equally effective pollinators, we suggest that honey-bees have the potential to reduce the amount of pollen available for plant reproduction, and to reduce the amount of resources available to solitary bee communities. The results of this study have potential implications for the conservation of this highly endangered plant species if hives are permitted inside reserves, where the bulk of Oncocyclus iris species are protected.     

Programmed cell death promotes male sterility in the functional dioecious Opuntia stenopetala (Cactaceae)

Background and Aims

The sexual separation in dioecious species has interested biologists for decades; however, the cellular mechanism leading to unisexuality has been poorly understood. In this study, the cellular changes that lead to male sterility in the functionally dioecious cactus, Opuntia stenopetala, are described.

Methods

The spatial and temporal patterns of programmed cell death (PCD) were determined in the anthers of male and female flowers using scanning electron microscopy analysis and histological observations, focusing attention on the transition from bisexual to unisexual development. In addition, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling assays were used as an indicator of DNA fragmentation to corroborate PCD.

Key results

PCD was detected in anthers of both female and male flowers, but their patterns differed in time and space. Functionally male individuals developed viable pollen, and normal development involved PCD on each layer of the anther wall, which occurred progressively from the inner (tapetum) to the outer layer (epidermis). Conversely, functional female individuals aborted anthers by premature and displaced PCD. In anthers of female flowers, the first signs of PCD, such as a nucleus with irregular shape, fragmented and condensed chromatin, high vacuolization and condensed cytoplasm, occurred at the microspore mother cell stage. Later these features were observed simultaneously in all anther wall layers, connective tissue and filament. Neither pollen formation nor anther dehiscence was detected in female flowers of O. stenopetala due to total anther disruption.

Conclusions

Temporal and spatial changes in the patterns of PCD are responsible for male sterility of female flowers in O. stenopetala. Male fertility requires the co-ordination of different events, which, when altered, can lead to male sterility and to functionally unisexual individuals. PCD could be a widespread mechanism in the determination of functionally dioecious species.     

Peduncles elicit large-mammal endozoochory in a dry-fruited plant

Background and Aims

Plants have evolved a variety of seed dispersal mechanisms to overcome lack of mobility. Many species embed seeds in fleshy pulp to elicit endozoochory, i.e. disseminating seed through the animal gut. In contrast to well-studied fleshy fruited plants, dry-fruited plants may exploit this dispersal mutualism by producing fleshy appendages as a nutritional reward to entice animals to swallow their diaspores, but this has been little studied. In this study, it is hypothesized that these accessory fruits represent co-adaptations facilitating the syndrome of mammalian endozoochorous dispersal.

Methods

Field observations (focal tree watches, faecal surveys and fruiting phenology) with experimental manipulations (examination of seed germination and feeding trials) were conducted over 2 years in a native population of the raisin tree, Hovenia dulcis, which produces enlarged, twisted brown peduncles with external black seeds, in central China.

Key Results

Birds were not observed to swallow seeds or carry infructescences away during 190 h of focal tree watches. However, H. dulcis seeds were detected in 247 faecal samples, representative of two herbivore and four carnivore mammalian species. Feeding trials revealed that peduncles attracted mammals to consume the entire infructescence, thereby facilitating effective seed dispersal. The germination rate of egested seeds proved higher than that of unconsumed seeds. It was also noted that this mutualism was most vulnerable in degraded forest.

Conclusions Hovenia dulcis

peduncle sets are confirmed to adapt primarily to mammalian endozoochory, a mutualistic association similar in function to fleshy pulp or foliage. This demonstrates that plant organ systems can be adapted to unique mutualisms that utilize animal dispersal agents. Such an ecological role has until now been attributed only to bird epizoochory. Future studies should consider more widely the putative role of peduncle sets and mammalian endozoochory as a dispersal mechanism, particularly for those plants that possess relatively large accessory fruits.     

How Much Demand for New HIV Prevention Technologies Can We Really Expect? Results from a Discrete Choice Experiment in South Africa

Background

For the first time in the history of HIV, new bio-medical interventions have been shown to be effective in preventing HIV transmission. For these new HIV prevention technologies (NPTs) to have an impact on the epidemic, they must be widely used. This study uses a discrete choice experiment (DCE) to: understand the relative strength of women’s preferences for product characteristics, understand the implications for substitution away from male condoms, and inform realistic modelling of their potential impact and cost-effectiveness.

Methods

A DCE was conducted among 1017 women in urban South Africa. Women were presented with choices between potential women’s NPTs (microbicides, diaphragm, female condom) and ‘what I did last time’ (use or not use a condom) with different HIV and pregnancy prevention effectiveness’ and prices. Choice probabilities are estimated using the nested logit model and used to predict uptake.

Results

In this high HIV prevalence setting, HIV prevention effectiveness is the main driver of uptake followed by pregnancy prevention effectiveness. For example a microbicide with poor effectiveness would have niche appeal at just 11% predicted uptake, while a highly effective microbicide (95% effective against HIV and pregnancy) would have far wider appeal (56% predicted uptake). Though women who reported not using condoms were more likely to choose the NPTs, at current very high rates of male condom use in South Africa (60%), about half of microbicide uptake is projected to be among those currently not using condoms.

Conclusions

Women are very interested in NPTs, especially if highly effective in preventing HIV and pregnancy. Women in greatest need were also most likely to switch to the new products. Where products are not yet available for distribution, proxy data, such as that generated by DCEs, can bring realism to overly optimistic uptake scenarios found in many current impact models.     

Traditional Male Circumcision in Uganda: A Qualitative Focus Group Discussion Analysis

Background

The growing body of evidence attesting to the effectiveness of clinical male circumcision in the prevention of HIV/AIDS transmission is prompting the majority of sub-Saharan African governments to move towards the adoption of voluntary medical male circumcision (VMMC). Even though it is recommended to consider collaboration with traditional male circumcision (TMC) providers when planning for VMMC, there is limited knowledge available about the TMC landscape and traditional beliefs.

Methodology and Main Findings

During 2010–11 over 25 focus group discussions (FGDs) were held with clan leaders, traditional cutters, and their assistants to understand the practice of TMC in four ethnic groups in Uganda. Cultural significance and cost were among the primary reasons cited for preferring TMC over VMMC. Ethnic groups in western Uganda circumcised boys at younger ages and encountered lower rates of TMC related adverse events compared to ethnic groups in eastern Uganda. Cutting styles and post-cut care also differed among the four groups. The use of a single razor blade per candidate instead of the traditional knife was identified as an important and recent change. Participants in the focus groups expressed interest in learning about methods to reduce adverse events.

Conclusion

This work reaffirmed the strong cultural significance of TMC within Ugandan ethnic groups. Outcomes suggest that there is an opportunity to evaluate the involvement of local communities that still perform TMC in the national VMMC roll-out plan by devising safer, more effective procedures through innovative approaches.