Acorn Tannins Research Articles

High-tannin food enhances spatial memory and scatter-hoarding in rodents via the microbiota-gut-brain axis

BackgroundThe mutually beneficial coevolutionary relationships between rodents and plant seeds have been a theme of research in plant-animal relationships. Seed tannins are important secondary metabolites of plants that regulate the food-hoarding behavior of rodents; however, the underlying molecular mechanisms are not yet clear. In this study, we investigated whether and how seed tannins improve spatial memory and regulate the hoarding behavior of Tamias sibiricus by altering their gut microbiota.ResultsWe showed that acorn tannins not only improved spatial memory but also enhanced scatter-hoarding in T. sibiricus. Changes in the composition and function of the gut microbiota in response to tannins from acorns are closely related to these improvements. Metabonomic analyses revealed the role of gut isovaleric acid and isobutyric acid as well as serum L-tryptophan in mediating the spatial memory of T. sibiricus via the gut microbiota. The hippocampal proteome provides further evidence that the microbiota-gut-brain axis regulates spatial memory and scatter-hoarding in animals. Our study is likely the first to report that plant secondary metabolites improve hippocampal function and spatial memory and ultimately modulate food-hoarding behavior via the microbiota-gut-brain axis.ConclusionOur findings may have resolved the long-standing puzzle about the hidden role of plant secondary metabolites in manipulating food-hoarding behavior in rodents via the microbiota-gut-brain axis. Our study is important for better understanding the mutualistic coevolution between plants and animals.-v6UxNpVaqDZi2u857RxwnVideo

Effect of Using Urea Formaldehyde Modified with Extracts in Plywood on Formaldehyde Emission

Formaldehyde-based adhesives are used in the forestry industry. This is because formaldehyde is inexpensive, easy to use and resistant to moisture; it also has particular mechanical effects. Formaldehyde has both advantages and disadvantages. It is known that various diseases such as lung cancer occur in humans as a result of the release of formaldehyde into the air during and after board production. In this study, a urea formaldehyde glue mixture was prepared by using four different fillers (extract of maritime pine (Pinus pinaster) and elm (Ulmus glabra) bark, extract of hazelnut (Corylus avellana) husk and acorn tannins) at two different ratios. The bonding shear strength of pine (Pinus sylvestris) and spruce (Picea orientalis) plywood produced with urea formaldehyde adhesive was tested according to EN 314-1 standard. All plywood, except the plywood with acorn tannin, met the requirements of the standard. A formaldehyde emission test of the plywood was carried out in accordance with EN 713-3 standard. With this approach, it is possible to quickly determine formaldehyde emissions. Experimental results were obtained for subsequent measurements, including chamber tests. It was observed that the elm bark extract reduced the formaldehyde emission of pine plywood by 40 %, while other fillers reduced it by 3-37 %.

Response surface optimization of the enzyme-based ultrasound-assisted extraction of acorn tannins and their corrosion inhibition properties

In this work, a highly efficient enzyme-based ultrasound-assisted method for the extraction of tannins from acorns was demonstrated and optimized. Based on a three-level four-factor Box Behnken Design (BBD), response surface methodology (RSM) was carried out to optimize the extraction conditions, including the ultrasonic time, ultrasonic power, cellulose concentration, and extraction temperature. Additionally, a second-order polynomial fit was performed to fit the experimental data. The optimized conditions were obtained, including the ultrasonic time (2.51 h), ultrasonic power (97.92 W), cellulose concentration (3.44 g/L), and extraction temperature (38.00 °C). Furthermore, the experimental extraction yield was 63.16 ± 0.12% under the optimal extraction conditions, which was in good agreement with the predictive yield of 63.42%. Interestingly, the potentiodynamic polarization and electrochemical impedance spectroscopy demonstrated that the extracted tannins exhibited the good corrosion inhibition for the mild steel in the NaCl solution. The corrosion inhibition efficiency of tannins reached 86.0%.

Some Physical and Mechanical Properties of Impregnated Chestnut Wood with Natural and Chemical Agent Exposed to Outdoor Conditions

Wood preservatives have been widely used to extend the service life of wood. The most objectionable environment for wood is outdoor conditions. In this study, test specimens prepared from chestnut wood (Castanea sativa Mill) were impregnated with natural and chemical impregnation agent. It was aimed to determine the effect of outdoor conditions on physical and mechanical properties of wood material by keeping them under these conditions for one year. As natural impregnation material pine tannin and acorn tannins, as chemical impregnation material imersol aqua and timbercare aqua were used. The retention amount, air-dried density, bending strength, modulus of elasticity, compression strength parallel to fibers, adhesion strength parallel to fibers, screw withdrawal strength were determined. As a result, it can be said that the physical and mechanical test values can compare wood impregnated with natural impregnation materials to wood impregnated with chemical impregnation materials after one year exposed to outdoor conditions.

Different population responses of three sympatric rodent species to acorn masting—the role of tannin tolerance

AbstractRodent population dynamics are predicted to respond positively to the masting of acorns, but diverging results have been published. This study tested the hypothesis that population responses to acorn masting vary depending on differences in the tolerance to tannins of different rodent species. The effects of acorn abundance on the rodent population densities were analyzed using a dataset obtained in Hokkaido, Japan. Specifically, population fluctuations of three rodent species (Apodemus speciosus, A. argenteus, and Myodes rufocanus) and the abundance of Quercus crispula acorns have been monitored since 1992. Acorn production in previous years had a positive effect on the annual population growth rates of A. speciosus; however, this trend was not clear in the other two species. Tannin tolerance, assessed by body weight changes in an acorn feeding experiment, exhibited clear differences among the rodent species; namely, the body weight of A. speciosus increased, whereas that of the other two species decreased. The observed responses to acorn masting of populations of the three sympatric rodent species reflected tannin tolerance. It suggests that only populations of species with high tannin tolerance positively respond to acorn masting. Previous studies tend to overlook species‐specific abilities of coping with tannins in acorns. Our results emphasize the necessity of evaluating the tannin tolerance of rodents and the tannin content of acorns to understand how rodent population dynamics and acorn production are related.

한국의 주요 참나무류 종실의 탄닌 및 영양성분 비교

참나무류 종실에 대한 수종별 성분함량 특성을 비교하기 위하여 동일 환경조건에서 생산된 채종원산 상수리나무, 졸참나무, 굴참나무 및 신갈나무 종실의 전체 페놀, 탄닌류, 아미노산, 무기원소, 식이섬유소, 베타카로틴 등의 함량을 분석하였다. 탄닌의 함량은 수종간에 유의적 차이(p<0.05)가 있었다. 졸참나무에서 79 mg/g으로 가장 높았고, 이외 수종은 62 mg/g 전후로 유사한 함량을 나타냈다. 수용성 탄닌 함량은 졸참나무가 71 mg/g을, 이외의 수종은 45 mg/g 전후로 나타났다. 반면 비수용성 탄닌 함량은 졸참나무가 8.2 mg/g으로 가장 낮았고, 굴참나무 23.5 mg/g으로 가장 높게 함유하고 있는 것으로 나타났다. 전체 식이섬유소 함량은 신갈나무 종실이 42%로 가장 높았고 졸참나무 38%, 상수리 및 굴참나무가 26% 전후로, 특히 졸참나무와 상수리나무의 클론간의 식이섬유소 함량을 비교한 결과 두 수종간에 유의적 차이(p<0.01)가 있었다. 무기성분 및 아미노산 함량은 신갈나무 종실이 다른 수종에 비해 높게 함유하는 경향이었다. 반면 베타카로틴은 신갈나무가 <TEX>$10{\mu}g/100g$</TEX>으로 가장 낮았고 굴참나무가 <TEX>$520{\mu}g/100g$</TEX>으로 가장 높은 경향이었다. 이상의 결과로 참나무 수종에 따른 도토리의 페놀성 화합물이나 영양성분의 함량은 수종 간에 차이가 있어 참나무 도토리의 종류에 따라 맛이나 영양학적으로 차이가 있을 것으로 추정된다. Nutritional composition, including total phenolics, tannins and nutrient components, of acorns of Q. actissima, Q. serrata, Q. variabilis and Q. mongolica were analyzed. Acorns were collected from each tree species, which were grown in a seed orchard. Contents of both total phenolics and tannins in acorns of Q. serrata were higher than those of Q. actissima (p<0.05). Interestingly, Q. serrata contained the highest amount of water soluble tannins (71 mg/g dw) and the lowest levels of water insoluble tannins (8.1 mg/g dw) among 4 oak species, resulting that acorns of Q. serrata had the lowest proportion of insoluble tannins. Among 4 oak species tested, Q. mongolicav acorns contained the highest levels of both total dietary fiber (TDF) and ascorbic acid, while the content of beta-carotene in Q. mongolicav was 52-fold lower than that in Q. variabilis (<TEX>$520{\mu}g/100g$</TEX>). Our result showed that nutritional composition of acoms was significantly different between oak species, indicating that tastes or nutritional values might be different as well among major oak species in Korea.

Pigs use endogenous proline to cope with acorn (Quercus pubescens Willd.) combined diets high in hydrolysable tannins

Detrimental effects due to high intake of dietary tannins are described in the literature in different animal species after acorn (fruit of Genus Quercus) ingestion. By contrast, pigs seem to tolerate dietary regimes with considerable amounts of acorns. This study investigates whether the esophageal mucosa (pars non glandularis) of the stomach might be a susceptible target for the onset of injuries and whether salivary proline rich proteins (PRPs) can be a valid defense to preserve its integrity, when a large amount of ripe shredded acorns (Quercus pubescens Willd.) is combined in the diet for growing pigs. A matched pair approach was used to divide a total of 16 crossbred growing pigs (14.2–27.6kg BW) into 2 groups (n=4 in each, homogeneous for BW) for 8 days of experimental feeding (two replicates): the control group was fed with a conventional complete diet for pigs (pelleted; 890g DM/kg; based on cereals and soybean meal). The acorn-fed group was offered a combined diet, 70% of ripe shredded acorns (612g DM/kg of fresh matter; Tannic Acid Equivalent, 0.516g TAE/kg DM) and 30% of the complete pelleted diet, as fed. Stomach ingesta were analyzed for chemical composition and proline content; on gross inspection, the gastric mucosa was exteriorized and scored (on a 0–5 point scale) for prevalence and severity of injuries. A sort of “tanning effect” underlined the edges of the cardiac gland region (CGR) in all the stomachs from the acorn-fed group, inducing to consider the high affinity of acorn tannins for PRP, such as gastric mucins. No signs of injury could be identified after both dietary treatments. The differential between the dietary proline intake and proline content in the stomach constantly showed a negative value (−46.1±9.72%) in the acorn-fed group, in contrast to the positive disappearance of proline in control group (39.3±25.4%). Therefore, endogenous proline for “buffering” purposes was considered to be a defense mechanism, either as a salivary or gastric mucus component.

Behavioral adaptation of Pallas's squirrels to germination schedule and tannins in acorns

Using acorns from Castanea henryi (CH) and Quercus variabilis (QV) with contrasting germination schedule (related to food perishability) and tannin levels, we conducted field experiments in a subtropical forest in Southwest China to investigate how free-ranging Pallas’s squirrels (Callosciurus erythraeus) utilize acorns as long-term storage based on the food perishability and hightannin hypotheses. Though QV acorns germinated much earlier than CH ones, we found that Pallas’s squirrels hoarded more high-tannin QV acorns over low-tannin CH ones, supporting the high-tannin hypothesis (but not the food perishability hypothesis). However, several other predictions derived from the food perishability hypothesis received sound support: nondormant QV acorns had their embryos removed with a higher probability (68.5%) than dormant CH ones (8.8%) and embryo-removed acorns had a much lower germination success but had a higher probability surviving as long-term storage. During the caching-recovery process, hoarding animals actively detected acorn state (dormant or not) and removed acorn embryos with an increasing probability in subsequent hoarding events. In addition, embryo-removed acorns could serve as long-term storage because they had a very low probability being infested by fungi as intact acorns did during the time of storage. We conclude that tree squirrels can differentially respond to acorn germination and remove the embryos of nondormant acorns more frequently as long-term storage, but tannin level is more important in determining whether a given acorn is hoarded or not. Combined with the studies from North America, our results suggest convergent evolution of acorn hoarding behavior in tree squirrels across different continents. Key words: behavioral decisions, germination schedule, long-term food supply, scatter hoarding, tannins, tree squirrels. [Behav Ecol]

Selective consumption of acorns by the Japanese wood mouse according to tannin content: a behavioral countermeasure against plant secondary metabolites

AbstractWe examined the presence of selective consumption against tannins in acorns as a pre‐ingestive countermeasure to plant secondary metabolites by using the Japanese wood mouse (Apodemus speciosus) and acorns of Quercus serrata, which contained ca. 6.4% tannins on a dry weight basis. In addition, the presence of selective consumption against proteins was also examined. In the acorn‐feeding experiment, 18 wood mice were allocated to two groups: the experienced group (N = 9), which had previous experience in feeding on acorns, and the inexperienced group (N = 9), which had no experience. Mice of both groups were fed only acorns for 3 nights. Selectivity against tannins (an index estimated from the tannin content in control, remaining, and ingested acorns) was significantly positive in the experienced group, indicating the presence of selective consumption against tannins. In contrast, mice in the inexperienced group did not show significant selectivity against tannins. Comparing the selectivity indices directly between two groups, however, they did not differ significantly. Selective consumption against proteins rather than that for proteins also occurred in the experienced group, but it was thought to be a byproduct resulted from the selectivity against tannins. Selective consumption against tannins can mitigate the negative effects of tannins by decreasing tannin intake.

Effects of acorn masting on population dynamics of three forest‐dwelling rodent species in Hokkaido, Japan

AbstractThe effects of the abundance of acorns of the oak, Quercus crispula, on the population dynamics of three rodent species (Apodemus speciosus, A. argenteus, and Clethrionomys rufocanus) were analyzed using time series data (1992–2006). The data were obtained in a forest in northern Hokkaido, Japan, by live trapping rodents and directly counting acorns on the ground. Apodemus speciosus generally increased in abundance following acorn masting. However, the clear effect of acorn abundance was not detected for the other two rodent species. Acorns of Q. crispula contain tannins, which potentially have detrimental effects on herbivores. Apodemus speciosus may reduce the damage caused by acorn tannins with tannin‐binding salivary proteins and tannase‐producing bacteria, whereas such physiological tolerance to tannins is not known in the other two rodent species. The differences in the effects of acorns between the three species may be due to differences in their physiological tolerance to tannins.

Role of Tannin-Binding Salivary Proteins and Tannase-Producing Bacteria in the Acclimation of the Japanese Wood Mouse to Acorn Tannins

We studied the defense mechanisms against the negative effects of tannins in acorns by using the Japanese wood mouse (Apodemus speciosus) and acorns of a Japanese deciduous oak Quercus crispula, which contain 9.9% tannins on a dry weight basis. For the experiment, we allocated 26 wood mice into two groups: acclimated (N = 12) and nonacclimated (N = 14). Mice in the nonacclimated group were fed only acorns for 10 d after 4 wk of receiving a tannin-free diet. In contrast, mice in the acclimated group received ca. 3 g acorns daily in addition to the tannin-free diet for the first 4 wk, then they were fed only acorns for 10 d. Body weight, food intake, and digestibility were monitored. In addition, the amount of salivary proline-rich proteins (PRPs) and abundance of tannase-producing bacteria (TPB) in the feces of mice were measured. Of the 14 mice in the nonacclimated group, 8 died, whereas only 1 of the 12 in the acclimated group died. During the first 5 d of feeding acorns only, mice in the nonacclimated group lost, on average, 17.5% of their body mass, while those in the acclimated group lost only 2.5%. Food intake, dry matter digestibility, and nitrogen digestibility were higher in the acclimated group than in the nonacclimated group. The results indicate that wood mice can mitigate the negative effects of tannins by acclimation. Path analysis revealed that increased secretion of PRPs and abundance of Lactobacillus type of TPB might explain the acclimation to tannins.

Does acclimation reduce the negative effects of acorn tannins in the wood mouseApodemus speciosus?

Acclimation as a mechanism of mitigating the damaging effects of acorn tannins was examined in the Japanese wood mouseApodemus speciosus Temminck, 1844. Mice were fed the two types of diet: a control diet (laboratory chow for mice), and acorns ofQuercus serrata (QS), which differ in tannin contents (control=0%, QS=2.7% tannic acid equivalent). Body weight changes and digestive abilities were compared between the first stage (Days 1 to 5; Day 0 was defined as the first day of acorn feeding) and the second stage (Days 6 to 10). The amount of salivary proline-rich proteins (PRPs), which are thought to be defensive products to tannins, was measured before and after the experiment. The responses of the wood mice to QS acorns differed between stages: decreases in body weight during the second stage were less than half those that occurred during the first stage; digestive abilities tended to improve; and the relative amount of PRPs after the experiment increased by a factor of five compared with the value recorded before the experiment in the QS-feeding mice. These results suggest that the negative effects of ingesting acorn tannins may be reduced by acclimation, which may result primarily from the induction of PRP production.

Negative effects of acorns on the wood mouse Apodemus speciosus

AbstractAntinutritional effects of acorns and tannic acid on the Japanese wood mouse Apodemus speciosus were examined in the laboratory. The first feeding experiment was conducted for 15 days using three types of diet: control diet (laboratory chow for mice), acorns of Quercus serrata (QS), and acorns of Q. mongolica var. grosseserrata (QM), which differ in tannin content (control, tannin free; QS, 2.7% tannic acid equivalent; QM, 8.5%). Six and one of eight mice died in the QM and QS groups, respectively, whereas all mice survived in good health in the control group. Body weight in the QM and QS groups decreased as much as 23.6% and 16.8% in the first 5 days, respectively, whereas that in the control group did not change significantly. Dry matter intake in the QM group was 50.0% and 38.7% less than that in the control and QS, respectively. Apparent dry matter digestibility was not different among the diets, but apparent nitrogen digestibility did differ between the two acorn groups (QM, −17.5%; QS, 12.0%). The logistic regression analyses revealed that the survival of mice was synergistically influenced by both dry matter intake and apparent nitrogen digestibility. In the second experiment, wood mice fed the tannin‐free formula diet, which is nutritionally matched to QS and QM acorns except for the tannin, did not suffer antinutritional effects, whereas mice fed the tannin‐supplemented formula diets suffered body weight loss and negative nitrogen digestibility. These results indicate that the tannins in acorns could cause serious damage to the wood mouse, which may rely on acorns as a usual diet. Plausible hypotheses explaining how the wood mice could overcome the deleterious effects of the acorns are discussed.

Effects of tannins on digestion and detoxification activity in gray squirrels (Sciurus carolinensis).

Acorn tannins may affect food preferences and foraging strategies of squirrels through effects on acorn palatability and digestibility and squirrel physiology. Captive eastern gray squirrels (Sciurus carolinensis) were fed 100% red oak (Quercus rubra) or white oak (Quercus alba) acorn diets to determine effects on intake, digestion, and detoxification activity. Red oak acorns had higher phenol and tannin levels, which may explain the lower dry matter intakes and apparent protein digestibilities and the higher glucuronidation activities observed in squirrels. Although the white oak acorn diet had lower apparent protein digestibilities than the reference diet, it did not suppress dry matter intake for a prolonged period or stimulate glucuronidation. Negative physiological effects of a 100% red oak acorn diet suggest gray squirrels may require other foods to dilute tannin intake and provide additional nutrients. To distinguish the roles of different tannin types in the observed effects of acorn diets on squirrels, squirrels were fed rat chow containing no tannins, 4% or 8% tannic acid (hydrolyzable tannin), or 3% or 6% quebracho (condensed tannin). Apparent protein digestibilities were reduced by tannic acid and quebracho diets. Only the 8% tannic acid diet tended to increase glucuronidation. Specific effects of tannins may largely depend on tannin type, composition, and source and on other nutritional and physiological factors.

Acorn selection by Mexican jays: a test of a tri-trophic symbiotic relationship hypothesis.

By caching acorns, jays serve as important dispersal agents for oak (Quercus) species. Yet little is known about which acorn characteristics affect selection by jays. In the traditional model of jay/oak symbiosis, large, brown, ripe acorns free of invertebrate parasites (e.g., Curculio acorn weevils) are selected by jays. Recently, it has been suggested that a tri-trophic relationship between oaks, jays, and weevils may have evolved to counter the negative dietary effects of acorn tannins. Under the tri-trophic model, jays would preferentially select acorns containing weevil larvae. We tested the assumptions that (1) acorns containing curculionid larvae exist in sufficient quantities to support jay populations and (2) jays can detect, and preferentially select, acorns containing weevil larvae, and investigated the cues by which jays select acorns. Captive Mexican jays (Aphelocomaultramarina) were presented Emory oak (Quercusemoryi) acorns in aviary feeding trials. Large, dense, viable acorns free of curculionid larvae were preferentially selected. Contrary to results of previous research, color did not affect selection. Acorn viability increased and curculionid larval occupancy decreased in adjacent savannas and isolated stands relative to existing oak woodland, perhaps favoring oak recruitment into adjacent lower-elevation grasslands. Our results compel us to reject the tri-trophic model for this system, and are consistent with the traditional jay/oak symbiosis model. Relatively long-distance dispersal of viable acorns favors Emory oak replacement, and spatial patterns of acorn viability and curculionid parasitism suggest expansion of Emory oak into adjacent low-elevation semi-arid grasslands.

Dietary circumvention of acorn tannins by blue jays : Implications for oak demography.

Blue jays consume large quantities of acorns to fuel energy-demanding caching flights in the fall. Yet blue jays possess no known physiological adaptation to counter the negative effects of a high tannin diet on protein digestion. Dietary experiments were conducted to determine if blue jays could subsist on an acorn-only diet, and if they could not, to determine whether supplements of acorn weevil larvae (Curculio), present inside acorns, enabled them to maintain their mass. Comparative tannin assays also were conducted on Lepidobalanus (low tannin; white oak) and Erythrobalanus (high tannin; pin oak) acorns using radial diffusion assay. Captive jays consumed considerable acorn material, yet were unable to maintain mass on ad lib. acorn-only diets or on an acorn +1.5 g larvae/day supplement. There were no significant differences in mass loss between high and low tannin diets. In contrast, blue jays were able to stabilize mass on a diet of acorns +5.0 g larvae supplement/day. These results suggest that acorn weevil larvae, or perhaps other insects, counteract the effects of acorn tannins in the jay diet allowing jays to subsist largely on acorns during the fall caching season. Oak demographic processes may be partly regulated by a tri-trophic relationship among plant, insect and bird. Acorn weevil larvae, considered damaging to oak populations, may actually facilitate oak recruitment and population vagility in the long-term.