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1. Juvenile Dungeness crabs ( Metacarcinus magister ) selectively integrate and modify the fatty acids of their experimental diets

   https://doi.org/10.1098/rstb.2020.0038  

   Thomas, Michael D.; Schram, Julie B.; Clark-Henry, Zade F.; Yednock, Bree K.; Shanks, Alan L.; Galloway, Aaron W. (August 2020, Philosophical Transactions of the Royal Society B: Biological Sciences)

   null (Ed.)

   Dungeness crabs ( Metacarcinus magister ) are ecologically and economically important in the coastal Northeast Pacific, yet relatively little is currently known about their feeding behaviour in the wild or their natural diet. Trophic biomarkers, such as fatty acids (FA), can be used to reveal trophic interactions. We used two feeding experiments to assess differences in FA composition of juvenile crabs fed different known foods to evaluate how they modify and integrate dietary FA into their own tissues and determine whether crab FA reflect diet changes over a six-week period. These experimental results were then compared with the FA signatures of wild caught juvenile crab with undetermined diets. We found that juvenile Dungeness crabs fed different foods assimilated dietary FA into their tissues and were distinct in their FA signatures when analysed with multivariate statistics. Experimentally fed juvenile crabs contained greater proportions of the most abundant long-chain polyunsaturated fatty acids (LCPUFA, >C20) than their foods. Crabs fed foods lacking in LCPUFA, particularly DHA (22:6 ω 3, docosahexaenoic acid), did not survive or grew slower than crabs fed other foods. This suggests that LCPUFA are physiologically important for this species and indicates biosynthesis of these FA does not occur or is not sufficient to meet their needs. This article is part of the theme issue ‘The next horizons for lipids as ‘trophic biomarkers’: evidence and significance of consumer modification of dietary fatty acids’. 

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2. Quantifying free simple sugars in orangutan foods using spectrophotometry: Implications for orangutan feeding ecology

   Robinson, Natalie; Lang, Lexi; Kane, Erin; Knott, Cheryl (April 2018, 87th Annual Meeting of the American Association of Physical Anthropologists)

   Orangutans (Pongo pygmaeus wurmbii) in Gunung Palung National Park, West Kalimantan, Indonesia experience significant seasonal and annual fluctuations in the availability of their preferred food, ripe fruit. When ripe fruit is limited, orangutans increase their consumption of bark, pith, and leaves, which are continuously available and may act as fallback foods. While these foods are presumed to be less nutritious, it is not clear whether this is the case. Free simple sugars (FSS) provide orangutans with readily-metabolizable energy, and are thus an important nutritional compound for food choice. Here, we examine FSS concentrations in a variety of orangutan foods (n=54) to better understand orangutan foraging and nutritional ecology. We predicted that preferred foods would have higher concentrations of FSS than fallback foods. We analyzed FSS concentrations using a modified phenol-sulfuric acid method, and tested sample absorbency using a spectrophotometer at 490 nm. We analyzed 54 samples from 48 species, examining six plant parts: bark, flowers, leaves, pulp, seeds, and skin/pulp. Although preliminary results indicated no statistically significant differences in sugar content across the six food categories (F(5,47)=1.78, p=0.14), we did find that preferred foods (fruit pulp and seeds) had an average sugar concentration that was significantly higher (4.7%) than fallback foods (leaves and bark) (t=2.355, p=0.04). Therefore, as predicted, we find that orangutans prefer food types with higher concentrations of FSS. Obtaining adequate caloric and nutritional intake is crucial for orangutan reproduction and development, and thus this study provides new insight into what drives orangutan dietary choices. National Science Foundation (BCS-1638823, BCS-0936199, 9414388), National Geographic Society, US Fish and Wildlife (F15AP00812, F12AP00369, 98210-8-G661), Leakey Foundation, Disney Wildlife Conservation Fund, Wenner-Gren Foundation, Nacey- Maggioncalda Foundation. 

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3. Persistent epigenetic reprogramming of sweet taste by diet

   https://doi.org/10.1126/sciadv.abc8492  

   Vaziri, Anoumid; Khabiri, Morteza; Genaw, Brendan T.; May, Christina E.; Freddolino, Peter L.; Dus, Monica (November 2020, Science Advances)

   null (Ed.)

   Diets rich in sugar, salt, and fat alter taste perception and food preference, contributing to obesity and metabolic disorders, but the molecular mechanisms through which this occurs are unknown. Here, we show that in response to a high sugar diet, the epigenetic regulator Polycomb Repressive Complex 2.1 (PRC2.1) persistently reprograms the sensory neurons of Drosophila melanogaster flies to reduce sweet sensation and promote obesity. In animals fed high sugar, the binding of PRC2.1 to the chromatin of the sweet gustatory neurons is redistributed to repress a developmental transcriptional network that modulates the responsiveness of these cells to sweet stimuli, reducing sweet sensation. Half of these transcriptional changes persist despite returning the animals to a control diet, causing a permanent decrease in sweet taste. Our results uncover a new epigenetic mechanism that, in response to the dietary environment, regulates neural plasticity and feeding behavior to promote obesity. 

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4. Effect of dietary macronutrients and immune challenge on gut microbiota, physiology and feeding behaviour in zebra finches

   https://doi.org/10.1111/mec.17428  

   Love, Ashley C; Tabb, Victoria; Youssef, Noha H; Wilder, Shawn M; DuRant, Sarah E (July 2024, Molecular Ecology)

   Bonneaud, Camille (Ed.)

   Abstract Macronutrients play a vital role in host immunity and can influence host–pathogen dynamics, potentially through dietary effects on gut microbiota. To increase our understanding of how dietary macronutrients affect physiology and gut microbiota and investigate whether feeding behaviour is influenced by an immune threat, we conducted two experiments. First, we determined whether zebra finches (Taeniopygia guttata) exhibit shifts in physiology and gut microbiota when fed diets differing in macronutrient ratios. We found the type and amount of diet consumed affected gut microbiota alpha diversity, where microbial richness and Shannon diversity increased with caloric intake in birds fed a high‐fat diet and decreased with caloric intake in birds fed a high protein diet. Diet macronutrient content did not affect physiological metrics, but lower caloric intake was associated with higher complement activity. In our second experiment, we simulated an infection in birds using the bacterial endotoxin lipopolysaccharide (LPS) and quantified feeding behaviour in immune challenged and control individuals, as well as birds housed near either a control pair (no immune threat), or birds housed near a pair given an immune challenge with LPS (social cue of heightened infection risk). We also examined whether social cues of infection alter physiological responses relevant to responding to an immune threat, an effect that could be mediated through shifts in feeding behaviour. LPS induced a reduction in caloric intake driven by a decrease in protein, but not fat consumption. No evidence was found for socially induced shifts in feeding behaviour, physiology or gut microbiota. Our findings carry implications for host health, as sickness‐induced anorexia and diet‐induced shifts in the microbiome could shape host–pathogen interactions. 

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5. Bats generate lower affinity but higher diversity antibody responses than those of mice, but pathogen-binding capacity increases if protein is restricted in their diet

   https://doi.org/10.1371/journal.pbio.3002800  

   Crowley, Daniel E; Falvo, Caylee A; Benson, Evelyn; Hedges, Jodi; Jutila, Mark; Ezzatpour, Shahrzad; Aguilar, Hector C; Ruiz-Aravena, Manuel; Ma, Wenjun; Schountz, Tony; et al (September 2024, PLOS Biology)

   Streicker, Daniel G (Ed.)

   Bats are reservoirs of many zoonotic viruses that are fatal in humans but do not cause disease in bats. Moreover, bats generate low neutralizing antibody titers in response to experimental viral infection, although more robust antibody responses have been observed in wild-caught bats during times of food stress. Here, we compared the antibody titers and B cell receptor (BCR) diversity of Jamaican fruit bats (Artibeus jamaicensis; JFBs) and BALB/c mice generated in response to T-dependent and T-independent antigens. We then manipulated the diet of JFBs and challenged them with H18N11 influenza A-like virus or a replication incompetent Nipah virus VSV (Nipah-riVSV). Under standard housing conditions, JFBs generated a lower avidity antibody response and possessed more BCR mRNA diversity compared to BALB/c mice. However, withholding protein from JFBs improved serum neutralization in response to Nipah-riVSV and improved serum antibody titers specific to H18 but reduced BCR mRNA diversity. 

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