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

The 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.     

Negative effects of acorns on the wood mouse <Emphasis Type="Italic">Apodemus speciosus</Emphasis>

 Antinutritional 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. Received: May 9, 2002 / Accepted: December 6, 2002     

Re-evaluation of the relationship between rodent populations and acorn masting: a review from the aspect of nutrients and defensive chemicals in acorns

The responses of rodent populations to acorn masting were examined by reviewing 17 studies from the aspect of acorn nutrients and defensive chemicals. Oak species were grouped into three types based on their acorn nutritional characteristics by cluster analysis: Type 1 acorns (two North American red oaks, subgenus Erythrobalanus) were high in tannins and high in fat and proteins (and consequently rich in metabolizable energy); Type 2 acorns (two Japanese evergreen oaks, Cyclobalanopsis; three Japanese deciduous oaks, Lepidobalanus; one North American white oak, Lepidobalanus) were high in tannins but low in fat and proteins; and Type 3 acorns (one Cyclobalanopsis species; seven Lepidobalanus species) were low in tannins and had intermediate levels of fat and proteins. These three acorn groups were nutritionally, and thereby ecologically, not equivalent. Rodents, in general, responded differently to acorn masting depending on their feeding habits and the nutritional characteristics of acorns. Granivorous rodents showed positive responses to masting of Type 1 and 3 acorns, whereas rodents with feeding habits intermediate between granivory and herbivory showed positive responses to masting of Type 3 acorns. In addition, for herbivorous rodents, the responses to masting of any types of acorns have not been reported. The present findings emphasize that the relationship between rodents and acorn masting should not easily be generalized, because there are large variations in characteristics of both acorns and rodents. The viewpoint presented in this review could offer more convincing interpretations to the contradictory observations, found in the studies reviewed, on the response of rodent populations to acorn masting.     

Hoarding behaviors of two wood mouse species: Different preference for acorns of two Fagaceae species

Two species of wood mouse, Apodemus argenteus and A. speciosus, were observed consuming and hoarding acorns of Quercus serrata and Castanopsis cuspidata. When each species of acorn was supplied individually, both species of mice used each species of acorn for eating and hoarding. When both species of acorn were supplied, A. argenteus consumed or hoarded only C. cuspidata, whereas A. speciosus tended to eat C. cuspidata acorns at the feeding site, and disperse or hoard Q. serrata acorns. Apodemus speciosus is unlikely to disperse C. cuspidata acorns (their utilization was biased towards consumption) when Q. serrata acorns are also available. Apodemus argenteus will make almost no contribution to the dispersal of Q. serrata when the two acorn species coexist.     

Enzymatic surface functionalisation of lignocellulosic materials with tannins for enhancing antibacterial properties

Grafting natural antibacterial phenols onto lignocellulosic materials is an environmentally friendly way of imparting antibacterial properties to the substrates. In the present investigation, wood veneer and pulp were treated with tannins in the presence or absence of laccase. Treatments with hydrolysable tannins significantly improved the antibacterial resistance of veneers and paper made from tannin-treated pulp against a Gram-positive bacterium (Staphylococcus aureus) while a more modest protective effect was observed against a Gram-negative bacterium (Escherichia coli). Condensed tannin improved the antibacterial resistance against S. aureus, albeit less than hydrolysable tannin, but had little effect on E. coli. A cationic condensed tannin derivative bearing a quaternary amino group provided far better resistance to pulp against S. aureus and E. coli than the corresponding unmodified condensed tannin. These findings agree with the minimal inhibitory concentrations (MICs) of the tannins and their reactivities toward laccase as determined by O₂ consumption measurements. Due to a better retention of tannins via covalent bonding, treatments with laccase usually resulted in greater antibacterial effects than those without laccase. LC–MS investigations with monomeric tannin and lignin model compounds showed that covalent bonding of tannin to lignin via radical coupling occurred in the presence of laccase.     

Nutrient compositions of acorns and horse chestnuts in relation to seed-hoarding

Nutritional compositions of acorns (Quercus serrata Thunb. and Quercus mongolica Fisch. var. grosseserrata Rehd. et Wils.) and horse chestnuts (Aesculus turbinata Blume) were analyzed. Major nutrients of acorns and horse chestnuts were carbohydrate, protein and fat. They proved to contain considerable amounts of tannins (7.28–11.72% dry mass^–1) and saponins (6.20%), respectively. The nutrients and the secondary metabolites of seeds buried for either 1 month or 3 months were analyzed to evaluate effects of seed-caching by animals. Noticeable changes were not observed, which suggested that caching may not bring any advantages to the seed-hoarders with respect to nutrition.     

Acorn Pericarp Removal as a Cache Management Strategy of the Siberian Chipmunk,Tamias sibiricus

Numerous recent studies have revealed a variety of behavioral adaptations of rodents for maximizing returns from cached seeds. Herein we report on a novel behavior by the Siberian chipmunk (Tamias sibiricus) in northeastern China, by which they consistently remove the pericarp (shell) of Quercus mongolica acorns before dispersing and caching these nuts. We investigated the effects of pericarp removal on acorn germination, tannin concentrations, cache pilferage, and insect damage, to determine if and how pericarp removal facilitates cache management by Siberian chipmunks and whether or not such behavior influences seed fates. Chipmunks cached acorns only after the pericarps were removed. Chipmunks preferred pericarp‐removed acorns over intact acorns when removing them from seed stations for both consumption and caching. Pericarp removal did not affect germination or tannin concentration of cached Q. mongolica acorns, suggesting that the behavior is not an adaptation for long‐term storage and tannin decomposition. Acetone treatments of the pericarp and artificial pericarp removal failed to alter pilferage rates by Siberian chipmunks and wood mice (Apodemus peninsulae). Since damage of acorns by weevils often leads to cache losses, we also tested the effects of weevil infestation on cache decision following pericarp removal. Siberian chipmunks removed pericarps and then scatter hoarded significantly more sound than weevil‐infested acorns, strongly suggesting that pericarp removal is used to discriminate between the infested and non‐infested acorns. Thus, we argue that the primary function of this behavior is to ensure successful storage of sound acorns, at least for short‐term storage. Future studies should consider the potential impact of pericarp removal on weevil populations and long‐term patterns of seed survival and establishment from the Siberian chipmunk’s caches.     

Not only size matters: Acorn selection by the European jay (Garrulus glandarius)

A strong selection for acorn characteristics is expected to have evolved in the mutualistic relationship between the European jay (Garrulus glandarius) and the oak (Quercus spp.). Bossema's pioneer work suggested that jays do not select acorns randomly, but rather they preferentially select some size and species. Preference for some seeds over others may have implications on plant community dynamics by conferring advantages (or disadvantages) on the selected (avoided) seed characteristics. In this paper we test to what extent jays select acorns by species and/or by size and the relation between these two traits in Mediterranean oak species. The experiments consist of a set of field tests in which acorns from four different coexisting Mediterranean oak species (Quercus ilex, Quercus faginea, Quercus suber, and Quercus coccifera) were placed in artificial feeders accessible to wild jays. The acorns were previously measured to control individual acorn characteristics. Using video-recording techniques, we followed jay activity and the fate of each acorn (sequence of acorn selection and method of transport). Q. ilex acorns were preferred over other acorns, and Q. coccifera acorns were avoided when other acorns were available. Preference for Q. faginea and Q. suber acorns was intermediate, that is, they were preferred over Q. coccifera acorns but not over Q. ilex acorns. Large acorns were also preferred although acorn species selection was stronger than size selection. Jays selected species and size both by visual means and by using acorn area as an indicator of size. Acorns wider than 17–19 mm were carried in the bill because of throat limitation. Our results confirm Bossema's study on temperate oaks and extend it to Mediterranean oak species, revealing implications on mixed oak forest dynamics.     

两种象甲幼虫肠道微生物组成及对高单宁食物的适应

【目的】象甲是栎属植物橡子中主要的寄生昆虫,但其适应高单宁食物(橡子)的肠道微生物基础尚待揭示。本研究分析了蒙古栎和辽东栎橡子中两种柞栎象(Curculio arakawai和C.dentipes)幼虫的肠道菌群结构和多样性,试图阐明柞栎象幼虫适应高单宁食物的肠道微生物基础。【方法】分别提取蒙古栎和辽东栎橡子中象甲幼虫各50头的肠道DNA,利用Illumina MiSeq技术对肠道菌群的V3–V4区序列进行16S rRNA测序,统计样品操作分类单元(OTU)数量,分析物种组成丰度、α多样性和β多样性。【结果】结果表明,可用于物种分类的OTU分别有2054和2308个,C. arakawai和C. dentipes共有的OUT 481个。在两种柞栎象C. arakawai和C. dentipes肠道菌群中,共注释到的主要分类阶元有27个门、145个科和274个属。变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)在两种象甲肠道菌群中占优势;假单胞菌属Pseudomonas(63.8%)、沙雷氏菌属Serratia(6%)和不动杆菌属Acinetobacter (5.2%)是C. arakawai肠道中的主要类群,而沙雷氏菌属Serratia (32%)、拉恩菌属Rahnella(24.2%)、气单胞菌属Aeromonas(6.8%)和立克次体属Rickettsia(6.6%)在C.dentipes肠道菌群中占主导优势。C. arakawai和C. dentipes肠道菌群α多样性无显著差异,β多样性则差异显著。具有单宁酶活性的肠道细菌,如粘质沙雷菌Serratia marcescens、乳球菌Lactococcus lactis、假单胞菌Pseudomonas spp.在C. arakawai和C. dentipes之间差异不显著。【结论】寄生在蒙古栎和辽东栎橡子中的C. arakawai和C.dentipes肠道菌群组成迥异,这可能与遗传因素和食物特点有关。具有单宁酶活性的粘质沙雷氏菌Serratia marcescens和乳球菌Lactococcus lactis等菌类可能是两种象甲幼虫适应高单宁食物的肠道微生物基础。     

The effect of nutrient supply and light intensity on tannins and mycorrhizal colonisation in Dutch heathland ecosystems

(1) Increased atmospheric nitrogen deposition has shifted plant dominance from ericaceous plants to grass species. To elucidate the reduced competitiveness of heather, we tested the hypothesis that additions of nitrogen reduce the concentrations of phenolics and condensed tannins in ericaceous leaves and retard mycorrhizal colonisation in ericaceous plants. We also tested the negative effects of reduced light intensity on carbon-based secondary compounds and mycorrhizal colonisation in ericaceous plants. (2) We performed a field inventory at three heathland sites in the Netherlands varying in nutrient supply and light intensity. Leaves of ericaceous plants and grasses were collected and analysed for concentrations of tannins, phenolics and nutrients. Similarly, we took root samples to record mycorrhizal colonisation and soil samples to measure the soil mineralisation. In addition, we conducted two-factorial experiments with Calluna vulgaris plants, in which we varied fertiliser and shade levels under greenhouse and field conditions. (3) The field inventory revealed that nitrogen addition and shading both negatively affected the concentration of total phenolics. The total phenolics and condensed tannin concentrations were positively correlated (P < 0.001), but in the field experiment, the condensed tannins were not significantly affected by the treatments. Our results provide the first evidence that the carbon nutrient balance can be used to predict the amount of total phenolics in the dwarf shrub C. vulgaris. (4) In the field experiments, shading of plants resulted in significantly less mycorrhizal colonisation. Only in the greenhouse experiment did addition of nitrogen negatively affect mycorrhizal colonisation. (5) Our results imply that increased atmospheric nitrogen deposition can depress the tannin concentrations in ericaceous plants and the mycorrhizal colonisation in roots, thereby reducing the plants’ competitiveness with respect to grasses. Additionally, if ericaceous plants are shaded by grasses that have become dominant due to increased nitrogen supply, these effects will be intensified and competitive replacement will be accelerated.     

Degradation of tannic acid and purification and characterization of tannase from Enterococcus faecalis

Tannins, present in various foods, feeds and forages, have anti-nutritional activity; however, presence of tannase in microorganisms inhabiting rumen and gastrointestinal tract of animals results in detoxification of these tannins. The present investigation was carried out to study the degradation profile of tannins by Enterococcus faecalis and to purify tannase. E. faecalis was observed to degrade tannic acid (1.0% in minimal media) to gallic acid, pyrogallol and resorcinol. Tannase from E. faecalis was purified up to 18.7 folds, with a recovery of 41.7%, using ammonium sulphate precipitation, followed by DEAE-cellulose and Sephadex G-150. The 45 kDa protein had an optimum activity at 40 °C and pH 6.0 at substrate concentration of 0.25 mM methyl gallate.     

Tannins from mimosoid legumes of Texas and Mexico

The percentage of tannins in leaves, bark, wood, and immature fruits of several species of Acacia and related mimosoid legumes from the southwestern U.S. and Mexico, along with a few from Costa Rica and Argentina, was determined by a modified hide powder procedure and by precipitation with casein. The relative percentages of hydrolyzable and condensed tannins were determined by the iodate and the vanillin-HCl methods, respectively. Gallotannins of selected samples were also determined by the rhodanine method. Although the amount of total tannins was similar for the first two methods, values for condensed tannins by the vanillin-HCl method were frequently two to four times greater than the total tannin values.     

Colorimetric assay of chitosan in presence of proteins and polyelectrolytes by using o-phthalaldehyde

A novel approach of colorimetric quantification of chitosan based on the derivatization reaction of its primary amino groups with o-phthalaldehyde and a thiol – N-acetyl-l-cysteine has been developed. The reaction of equal volumes of sample solution and the reagent solution was allowed to proceed for 1 h, and then the absorbance values were measured at 340 nm against the reference solution. The procedure conditions have been optimized for chitosan assay in the presence of polyanionic electrolyte dextran sulphate (pH 8.9, the reagent solution: 4.0 mM o-phthalaldehyde, 2.6 mM N-acetyl-l-cysteine, 0.25 M NaCl). The method has proven to be convenient and reliable for quantitative determination of either the concentrations of chitosans of various molecular weights or their degree of deacetylation. The different reactivity of chitosans and proteins can be used in order to determine chitosan in presence of the protein. This approach ensured accurate assay within the chitosan concentrations ranging from 0.01 to 0.15 mg/ml and could be applied for quantitative analysis of chitosan in protein-loaded microparticles.     

Evaluation of the white-rot fungi Ganoderma australe and Ceriporiopsis subvermispora in biotechnological applications

Ganoderma australe is a white-rot fungus that causes a selective wood biodelignification in some hardwoods found in the Chilean rainforest. Ceriporiopsis subvermispora is also a lignin-degrading fungus used in several biopulping studies. The enzymatic system responsible for lignin degradation in wood can also be used to degrade recalcitrant organic pollutants in liquid effluents. In this work, two strains of G. australe and one strain of C. subvermipora were comparatively evaluated in the biodegradation of ABTS and the dye Poly R-478 in liquid medium, and in the pretreatment of Eucalyptus globulus wood chips for further kraft biopulping. Laccase was detected in liquid and wood cultures with G. australe. Ceriporiopsis subvermispora produce laccase and manganese peroxidase when grown in liquid medium and only manganese peroxidase was detected during wood decay. ABTS was totally depleted by all strains after 8 days of incubation while Poly R-478 was degraded up to 40% with G. australe strains and up to 62% by C. subvermispora after 22 days of incubation. Eucalyptus globulus wood chips decayed for 15 days presented 1–6% of lignin loss and less than 2% of glucan loss. Kraft pulps with kappa number 15 were produced from biotreated wood chips with 2% less active alkali, with up to 3% increase in pulp yield and up to 20% less hexenuronic acids than pulps from undecayed control. Results showed that G. australe strains evaluated were not as efficient as C. subvermispora for dye and wood biodegradation, but could be used as a feasible alternative in biotechnological processes such as bioremediation and biopulping.     

Nondestructive determination of tannin content in intact individual acorns by near-infrared spectroscopy

To examine the effects of tannin content in acorns of Quercus serrata on the fate of individual seeds, we developed a system for nondestructive chemical analysis of single acorns by near-infrared spectroscopy. We modeled the relationship between the normalized second-derivative spectra and tannin content by partial least squares regression. We obtained the best calibration model (r ² = 0.836; standard error of calibration = 1.90; standard error of validation = 1.43; bias = 0.10). The regression coefficient plots showed that the key band for the model was 938 nm, close to the absorption band of tannic acid in aqueous solution.

     

Dietary circumvention of acorn tannins by blue jays

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.     

Effect of lectins from Opuntia ficus indica cladodes and Moringa oleifera seeds on survival of Nasutitermes corniger

Biodegradation by termites is a serious problem for wood and crop industries worldwide, and new environmentally friendly alternatives for termite control have been developed. This work investigated the effects of crude and purified preparations containing lectins from Opuntia ficus indica cladodes (OfiL) and Moringa oleifera seeds (WSMoL and cMoL) on Nasutitermes corniger workers and soldiers. Purified OfiL was more active than cladode extracts, showing a stronger termiticidal activity against workers (LC₅₀ of 0.116 mg ml⁻¹) than against soldiers. OfiL was active against soldiers only at 1.5 mg ml⁻¹. All preparations containing WSMoL and cMoL were active only at concentrations of 1.0 and 1.5 mg ml⁻¹. The tested preparations did not exert repellent activity against N. corniger. OfiL was able to kill workers and therefore is potentially a new tool for N. corniger control; as a consequence, this lectin could disturb organization, structure, and maintenance of termite colonies.     

Development of tannin vacuoles in chalaza and seed coat of barley in relation to early chalazal necrosis in the seg1 mutant

Structural development of grain tissues of maternal origin in normal and seg1 barley (Hordeum vulgare L. cv. Betzes) was examined using light and electron microscopy. Chalaza and seedcoat cells of normal grains developed prominent tannin vacuoles which persisted throughout the grain-filling period. Tannins were present in the same tissues of seg1, but no large central vacuoles developed. Instead, the chalaza and nucellar projection degenerated and were crushed, presumably terminating sugar flow and causing formation of shrunken grains (35–55% normal dry weight). Tannins were localized using various histochemical stains. Extracts of chalaza and adjacent tissues contained proanthocyanidins which yielded delphinidin and cyanidin upon hydrolysis in boiling HCl. We suggest that the basis of the seg1 phenotype may be abnormal compartmentation of tannins causing precipitation of cytoplasmic proteins and early death of chalazal cells.Abbreviations FAA Formalin-acetic acid-ethanol - PAS periodic acid Schiffs reagent     

In vitro mutagen binding and antimutagenic activity of human Lactobacillus rhamnosus 231

In vitro mutagen binding ability of human Lactobacillus rhamnosus 231 (Lr 231) was evaluated against acridine orange (AO), N-methyl-N’-nitro-N-nitrosoguanidine (MNNG), 2-amino-3, 8-dimethylimidazo-[4,5-f]-quinoxaline (MeIQx) and 4-nitro-o-phenylenediamine (NPD). Binding of AO by Lr 231 is due to adsorption, thereby leading to removal of mutagen in solution and is instantaneous, pH- and concentration-dependent. Whereas, binding of MNNG and MeIQx by Lr 231 results into biotransformation leading to detoxification with subsequent loss of mutagenicity as determined by spectral analysis, thin layer chromatography and Ames test. Binding of mutagen by Lr 231 was dependent on culture age and optimum binding of AO, MNNG and MeIQx was observed to occur with 24 h old culture. Cells of Lr 231 were subjected to different chemical treatments prior to binding studies. Results indicated cell wall component such as cell wall polysaccharide, peptidoglycan, carbohydrates and proteins plays an important role in adsorption of AO, also involving hydrophilic and ionic interactions. Binding, biotransformation and detoxification of MNNG and MeIQx by Lr 231 was dependent on cell surface characteristics mainly involving carbohydrates, proteins, teichoic acid/lipoteichoic acid, hydrophobic interaction and presence of thiol group. L. rhamnosus 231 bound MNNG instantaneously. More than 96 (p < 0.01) and 70% (p < 0.05) cells remained viable after mutagen binding and various pretreatments respectively. This study shows Lr 231 exhibits ability to bind and detoxify potent mutagens, and this property can be useful in formulating fermented foods for removal of potent mutagens.