Two different jumping mechanisms of water striders are determined by body size.

Current theory for surface tension-dominant jumps on water, created for small- and medium-sized water strider species and used in bioinspired engineering, predicts that jumping individuals are able to match their downward leg movement speed to their size and morphology such that they maximize the takeoff speed and minimize the takeoff delay without breaking the water surface. Here, we use empirical observations and theoretical modeling to show that large species (heavier than ~80 mg) could theoretically perform the surface-dominated jumps according to the existing model, but they do not conform to its predictions, and switch to using surface-breaking jumps in order to achieve jumping performance sufficient for evading attacks from underwater predators. This illustrates how natural selection for avoiding predators may break the theoretical scaling relationship between prey size and its jumping performance within one physical mechanism, leading to an evolutionary shift to another mechanism that provides protection from attacking predators. Hence, the results are consistent with a general idea: Natural selection for the maintenance of adaptive function of a specific behavior performed within environmental physical constraints leads to size-specific shift to behaviors that use a new physical mechanism that secure the adaptive function.

Avian mud nest architecture by self-secreted saliva.

Mud nests built by swallows (Hirundinidae) and phoebes (Sayornis) are stable granular piles attached to cliffs, walls, or ceilings. Although these birds have been observed to mix saliva with incohesive mud granules, how such biopolymer solutions provide the nest with sufficient strength to support the weight of the residents as well as its own remains elusive. Here, we elucidate the mechanism of strong granular cohesion by the viscoelastic paste of bird saliva through a combination of theoretical analysis and experimental measurements in both natural and artificial nests. Our mathematical model considering the mechanics of mud nest construction allows us to explain the biological observation that all mud-nesting bird species should be lightweight.

Dynamics of Bacterial Communities on Eggshells and on Nest Materials During Incubation in the Oriental Tit (Parus minor).

Eggshell bacterial communities may affect hatching success and nestling's condition. Nest materials are in direct contact with the eggshells, but the relationships with the eggshell microbiome during incubation have not been fully elucidated. Here, we characterize eggshell and nest material bacterial communities and their changes during incubation in the Oriental Tit (Parus minor). Bacterial communities on the nest material were relatively stable and remained distinct from the eggshell communities and had higher diversity and greater phylogenetic clustering than the eggshell communities from the same nest, resulting in lower phylogenetic turnover rate of nest material microbiome during incubation than expected by chance. While the species diversity of both communities did not change during incubation, we found significantly greater changes in the structure of bacterial communities on the eggshell than on the nest material. However, eggshell microbiome remained distinct from nest material microbiome, suggesting independent dynamics of the two microbiomes during incubation. We detected an increase in the relative abundance of several bacterial taxa on the eggshell that likely come from the bird's skin, feathers, cloaca/intestine, or uropygial secretion which suggests some exchange of bacteria between the incubating bird and the eggshell. Furthermore, incubation appeared to promote the abundance of antibiotic producing taxa on the eggshell, which may hypothetically inhibit growth of many bacteria including pathogenic ones. Our results suggest that the future studies should focus on simultaneous monitoring of absolute abundance as well as relative abundance in communities on eggshells, nest materials, and the incubating bird's body.

Antarctic skuas recognize individual humans.

Recent findings report that wild animals can recognize individual humans. To explain how the animals distinguish humans, two hypotheses are proposed. The high cognitive abilities hypothesis implies that pre-existing high intelligence enabled animals to acquire such abilities. The pre-exposure to stimuli hypothesis suggests that frequent encounters with humans promote the acquisition of discriminatory abilities in these species. Here, we examine individual human recognition abilities in a wild Antarctic species, the brown skua (Stercorarius antarcticus), which lives away from typical human settlements and was only recently exposed to humans due to activities at Antarctic stations. We found that, as nest visits were repeated, the skua parents responded at further distances and were more likely to attack the nest intruder. Also, we demonstrated that seven out of seven breeding pairs of skuas selectively responded to a human nest intruder with aggression and ignored a neutral human who had not previously approached the nest. The results indicate that Antarctic skuas, a species that typically inhabited in human-free areas, are able to recognize individual humans who disturbed their nests. Our findings generally support the high cognitive abilities hypothesis, but this ability can be acquired during a relatively short period in the life of an individual as a result of interactions between individual birds and humans.

Expression of thymosin beta-4 in human periodontal ligament cells and mouse periodontal tissue and its role in osteoblastic/cementoblastic differentiation.

A recent report showed that thymosin beta-4 (Tß4) is expressed during the development of tooth germ, but its effect on osteoblastic/cementoblastic differentiation is a controversial topic. Furthermore, the precise expression and function of Tß4 in periodontal tissue remains unclear. Therefore, the purpose of this study was to investigate the immunolocalization of Tß4 in the developing periodontium of mouse, the function of Tß4 in osteoblastic/cementoblastic differentiation, and the underlying mechanism regulating periodontal regeneration in human periodontal ligament cells (hPDLCs), cementoblasts, and osteoblasts. Tß4 expression was observed in differentiating hPDLCs, osteoblasts of the periodontium during development, as well as in mature tissue. Higher Tß4 expression was observed in hPDLCs than in cementoblasts and osteoblasts in the developing periodontium. The expression of Tß4 mRNA and protein gradually increased during PDL cell differentiation. The downregulation of Tß4 expression by Tß4 siRNA transfection inhibited osteoblastic differentiation by decreasing calcium nodule formation, alkaline phosphatase (ALP) activity, and mRNA expression of differentiation markers in hPDLCs, cementoblasts, and osteoblasts. In contrast, Tß4 activation using a Tß4 peptide, promoted these processes by activation of Akt, p38, ERK MAPKs, and the NF-κB pathway. The expression of nuclear NFATc1 was upregulated by Tß4 peptide in hPDLCs. Inhibition of the calcineurin/NFATc1 pathway by cyclosporin A and FK506, attenuated Tß4-induced osteoblastic differentiation and activation of Wnt-related genes, as well as nuclear ß-catenin in hPDLCs. In conclusion, this study demonstrates, for the first time, that Tß4 is expressed in developing periodontal tissue and that its expression is associated with osteoblastic/cementoblastic differentiation. These results suggests that Tß4 is a potential therapeutic target for periodontal regeneration or bone disease.

Muramyl dipeptide activates human beta defensin 2 and pro-inflammatory mediators through Toll-like receptors and NLRP3 inflammasomes in human dental pulp cells.

PURPOSE: The expression levels of intracellular pyrin domain-containing 3 (NLRP3) and microbial pattern-recognition receptors, such as nucleotide-binding oligomerization domain 2 (NOD2), have been reported in human dental pulp cells (HDPCs) and inflamed dental pulp tissue, but the role of NLRP3 and Toll-like receptors (TLRs) in the production of human beta defensin 2 (hBD2) and inflammatory cytokines against invading pathogens remains poorly defined. The aim of this study was to determine whether the NOD2 ligand muramyl dipeptide (MDP) upregulates hBD2 and inflammatory cytokines and whether this response is dependent on TLRs and NLRP inflammasomes in HDPCs. METHODOLOGY: The effects of MDP on the expression of hBD2, TLRs, inflammasomes, and pro-inflammatory mediators in HDPCs were examined using Western blotting and reverse transcription-polymerase chain reaction. Levels of pro-inflammatory cytokines, such as nitric oxide (NO) and prostaglandin E2 (PGE2), were determined by enzyme-linked immunosorbent assay. RESULTS: MDP upregulated hBD2, TLR2, and TLR4 mRNAs and protein levels in a dose- and time-dependent manner. TLR2 and TLR4 neutralizing blocking antibodies and NOD2- and hBD2-specific small interfering RNAs (siRNAs) attenuated the MDP-induced production of NO, PGE2, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and IL-8 and upregulated inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2) in HDPCs. Additionally, MDP activated inflammasome-related genes, such as NLRP3, caspase 1, apoptotic speck protein containing a caspase recruitment domain, and IL-1ß. Furthermore, silencing of the NLRP3 gene using a siRNA significantly decreased the MDP-induced expression of hBD2 and cytokines, such as iNOS-derived NO, COX2, PGE2, TNF-α, IL-6, and IL-8. CONCLUSION: These results suggest that NOD2 activates the TLR2, TLR4, and NLRP3 inflammasome-signaling pathways in HDPCs to induce the production of multiple inflammatory mediators and antimicrobial peptides, which in turn promote pulp immune defense against microbial challenge. CLINICAL RELEVANCE: The TLR and NLRP3 inflammasome pathways may represent an important modulatory mechanism of immune defense responses during the progression of pulpitis. Our results suggest that local inhibition of NLRP3 and TLRs may reduce the impact of cytokine-mediated host destructive processes in pulpitis.

Behavioral analysis of cloned puppies derived from an elite drug-detection dog.

Since the first cloned dog "Snuppy" was born, many cloned dogs have been produced by somatic cell nuclear transfer (SCNT) technology. We reported the production of seven cloned drug detection dogs (named "Toppies") in 2009. Although their genetic identity was confirmed, similarities in behavior and the drug-detecting ability were not examined. Therefore, this study is the first attempt to examine their behavior. We conducted the Campbell test which is commonly used to evaluate the tendency of dominance. Data were analyzed by the general linear mixed model. The scores among seven cloned puppies and four naturally-bred controls were significantly different (P < 0.0001). After the test, cloned and control puppies were trained according to the Korea Customs Detector Dog Training Center's manual. The selection rate for detector dog in the cloned puppies was higher (86 %) than that of naturally-bred dogs (30 %). Therefore, it can be concluded that drug detection dogs with high performance can be propagated more efficiently using SCNT.

Assessing dietary specialization to inform the conservation of the fairy pitta (Pitta nympha), an endangered vermivore.

Quantifying the diet of endangered species is crucial for conservation, especially for diet specialists, which can be more susceptible to environmental changes. The vulnerable fairy pitta (Pitta nympha) is considered a specialist that primarily feeds its nestlings with earthworms. However, there have been few studies of the nestling diet provisioned by parents, and no assessments of earthworm proportion in the diet of adults. Our study aimed to fill these gaps, shedding light on crucial factors for conservation. Combining new observations with existing literature, we confirmed a consistent dominance of earthworms in the nestling diet, regardless of rainfall, nestling age, and time of day. We extrapolated the total earthworm consumption during a breeding event, accounting for potential variation in the availability of earthworms and their prevalence in the adult diet. We used literature-based earthworm densities in pitta habitats and our estimates of family earthworm consumption to calculate the habitat area that could provide a pitta family with the number of earthworms consumed during a breeding event. The predictions matched observed pitta home range sizes when assumed that the adult diet is comprised of approximately 70% earthworms. The results highlight the importance of earthworm-rich habitats for conservation planning of the fairy pitta. To mitigate the effects of habitat destruction, we discuss conservation practices that may involve enhancing earthworm abundance in natural habitats and providing vegetation cover for foraging pittas in adjacent anthropogenic habitats rich in earthworms. To guide conservation efforts effectively, future studies should investigate whether previously reported breeding in developed plantation habitats is due to high earthworm abundance there. Future studies should also quantify correlations between local earthworm densities, home range size, and the breeding success of the fairy pitta.

The effect of avian eggshell membrane structure on microbial penetration: A simulation study.

Avian eggshells exhibit excellent antimicrobial properties. In this study, we conducted simulation experiments to explore the defense mechanisms of eggshell membranes with regards to their physical features. We developed a mathematical model for the movement of microorganisms and estimated their penetration ratio into eggshell membranes based on several factors, including membrane thickness, microbial size, directional drift, and attachment probability to membrane fibers. These results not only suggest that an eggshell membrane with multiple layers and low porosity indicates high antimicrobial performance, but also imply that the fibrous network structure of the membrane might contribute to effective defense. Our simulation results aligned with experimental findings, specifically in measuring the penetration time of Escherichia coli through the eggshell membrane. We briefly discuss the significance and limitations of this pilot study, as well as the potential for these results, to serve as a foundation for the development of antimicrobial materials.

Escape behaviors in prey and the evolution of pennaceous plumage in dinosaurs.

Numerous non-avian dinosaurs possessed pennaceous feathers on their forelimbs (proto-wings) and tail. Their functions remain unclear. We propose that these pennaceous feathers were used in displays to flush hiding prey through stimulation of sensory-neural escape pathways in prey, allowing the dinosaurs to pursue the flushed prey. We evaluated the escape behavior of grasshoppers to hypothetical visual flush-displays by a robotic dinosaur, and we recorded neurophysiological responses of grasshoppers' escape pathway to computer animations of the hypothetical flush-displays by dinosaurs. We show that the prey of dinosaurs would have fled more often when proto-wings were present, especially distally and with contrasting patterns, and when caudal plumage, especially of a large area, was used during the hypothetical flush-displays. The reinforcing loop between flush and pursue functions could have contributed to the evolution of larger and stiffer feathers for faster running, maneuverability, and stronger flush-displays, promoting foraging based on the flush-pursue strategy. The flush-pursue hypothesis can explain the presence and distribution of the pennaceous feathers, plumage color contrasts, as well as a number of other features observed in early pennaraptorans. This scenario highlights that sensory-neural processes underlying prey's antipredatory reactions may contribute to the origin of major evolutionary innovations in predators.

Sodium hydrogen sulfide inhibits nicotine and lipopolysaccharide-induced osteoclastic differentiation and reversed osteoblastic differentiation in human periodontal ligament cells.

Although previous studies have demonstrated that hydrogen sulfide (H(2)S) stimulated or inhibited osteoclastic differentiation, little is known about the effects of H(2)S on the differentiation of osteoblasts and osteoclasts. To determine the possible bioactivities of H(2)S on bone metabolism, we investigated the in vitro effects of H(2)S on cytotoxicity, osteoblastic, and osteoclastic differentiation as well as the underlying mechanism in lipopolysaccharide (LPS) and nicotine-stimulated human periodontal ligament cells (hPDLCs). The H(2)S donor, NaHS, protected hPDLCs from nicotine and LPS-induced cytotoxicity and recovered nicotine- and LPS-downregulated osteoblastic differentiation, such as alkaline phosphatase (ALP) activity, mRNA expression of osteoblasts, including ALP, osteopontin (OPN), and osteocalcin (OCN), and mineralized nodule formation. Concomitantly, NaHS inhibited the differentiation of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in mouse bone marrow cells and blocked nicotine- and LPS-induced osteoclastogenesis regulatory molecules, such as RANKL, OPG, M-CSF, MMP-9, TRAP, and cathepsin K mRNA. NaHS blocked nicotine and LPS-induced activation of p38, ERK, MKP-1, PI3K, PKC, and PKC isoenzymes, and NF-κB. The effects of H(2)S on nicotine- and LPS-induced osteoblastic and osteoclastic differentiation were remarkably reversed by MKP-1 enzyme inhibitor (vanadate) and expression inhibitor (triptolide). Taken together, we report for the first time that H(2)S inhibited cytotoxicity and osteoclastic differentiation and recovered osteoblastic differentiation in a nicotine- and periodontopathogen-stimulated hPDLCs model, which has potential therapeutic value for treatment of periodontal and inflammatory bone diseases.

Effect of nanostructural irregularities on structural color in the tail feathers of the Oriental magpie Pica serica.

The tail feathers of magpies are iridescent, with hues ranging from navy to violet and green. It has been previously shown that the hexagonal arrangement of melanosomes in the distal barbules is responsible for these colors, but previous simulation models have relied on average values for the parameters associated with this arrangement (e.g., periodicity), and it remains to be studied whether the actual (rather than averaged) structural arrangement and its inherent irregularities reliably predict structural color. Previous studies using unmodified images for the analysis have not focused on the effect of such irregularities on the color production. In this study, we conducted finite-difference time-domain (FDTD) simulations using actual transmission electron microscopy (TEM) images obtained from the distal barbules of a magpie tail feather, compared the reflectance spectra predicted using the FDTD simulation with those measured with a spectrometer, and found a substantial discrepancy between the two. Fourier analysis suggests that the non-uniform arrangement of the melanosomes within the barbule is responsible for this discrepancy by creating variation in the periodicity. Our results suggest that a simple model in which the parameters for internal structures are averaged cannot fully explain the variation in the structural colors observed in biological samples such as the feathers of birds.

Long-term memory of experienced jays facilitates problem-solving by naïve group members in the wild.

Long-term memory affects animal fitness, especially in social species. In these species, the memory of group members facilitates the acquisition of novel foraging skills through social learning when naïve individuals observe and imitate the successful foraging behavior. Long-term memory and social learning also provide the framework for cultural behavior, a trait found in humans but very few other animal species. In birds, little is known about the duration of long-term memories for complex foraging skills, or the impact of long-term memory on group members. We tested whether wild jays remembered a complex foraging task more than 3 years after their initial experience and quantified the effect of this memory on naïve jay behavior. Experienced jays remembered how to solve the task and their behavior had significant positive effects on interactions by naïve group members at the task. This suggests that natural selection may favor long-term memory of solutions to foraging problems to facilitate the persistence of foraging skills that are specifically useful in the local environment in social birds with long lifespans and overlapping generations.

Unlearned adaptive responses to heterospecific referential alarm calls in two bird species from separate evolutionary lineages.

The interspecific responses to alarm signals may be based on unlearned mechanisms but research is often constrained by the difficulties in differentiating between unlearned and learned responses in natural situations. In a field study of two Paridae species, Parus minor and Sittiparus varius, who originated from a common ancestor 8 million years ago, we found a considerable degree of between-species overlap in acoustic properties of referential snake-alarm calls. Playback of these calls triggered unlearned adaptive fledging behavior in conspecific and heterospecific naive nestlings, suggesting a between-species overlap in the hypothetical unlearned neural templates involved in nestlings' reactions to alarm calls in both species. This suggests that similar calls and similar unlearned sensitivity might have been present in the common ancestor of the two species, and possibly in the ancestor of the whole family Paridae that originated 10-15 million years ago in Asian regions rich in snakes.

Porphyromonas gingivalis lipopolysaccharide regulates interleukin (IL)-17 and IL-23 expression via SIRT1 modulation in human periodontal ligament cells.

Increased interleukin (IL)-17 and IL-23 levels exist in the gingival tissue of periodontitis patients, but the precise molecular mechanisms that regulate IL-17 and IL-23 production remain unknown. The aim of this study was to explore the role of SIRT1 signaling on Porphyromonas gingivalis lipopolysaccharide (LPS)-induced IL-17 and IL-23 production in human periodontal ligament cells (hPDLCs). IL-17 and IL-23 production was significantly increased in LPS-treated cells. LPS treatment also led to the upregulation of SIRT1 mRNA and protein expression. LPS-induced IL-17 and IL-23 upregulation was attenuated by pretreatment with inhibitors of phosphoinositide 3-kinase (PI3K), p38, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), mitogen-activated protein kinase (MAPK), and NF-κB, as well as neutralizing antibodies against Toll-like receptors (TLRs) 2 and 4. Sirtinol treatment (a known SIRT1 inhibitor) or SIRT1 knockdown by small interfering RNA blocked LPS-stimulated IL-17 and IL-23 expression. Further investigation showed that LPS decreased osteoblast markers (i.e., ALP, OPN, and BSP) and concomitantly increased osteoclast markers (i.e., RANKL and M-CSF). This response was attenuated by inhibitors of the PI3K, p38, ERK, JNK, NF-κB, and SIRT1 pathways. These findings, for the first time, suggest that human periodontopathogen P. gingivalis LPS is implicated in periodontal disease bone destruction and may mediate IL-17 and IL-23 release from hPDLCs. This process is dependent, at least in part, on SIRT1-Akt/PI3K-MAPK-NF-κB signaling.

Molecular tools for species and sex identification in the mixed-species flocks of bean geese and white-fronted geese.

Genetic studies on protected species can be difficult, particularly when they form a mixed-species flock with other species. The bean goose (Anser fabalis), which is internationally recognized as a threatened species, was observed to form overwintering foraging flocks with white-fronted goose (Anser albifrons) at agricultural lands to feed on the grains in Korea. Non-invasive samples such as feces and feather that are readily available in their foraging ground can be useful for understanding the structure and composition of populations, but they often require specific experimental conditions due to small amount or low quality of DNA. In this study, we designed sets of primers that would allow efficient molecular identification of species and sex of individuals of bean geese and white-fronted geese. Species-specific primers (WFG-F/BG-F and G-R), developed from ND2 region of mitochondrial DNA, produced PCR products with different sizes which allow easy species identification without further sequencing. Based on published CHD 1 sequences, we designed internal primers (Gsex-F and Gsex-R) for sex determination that can be used in nested PCR after applying P2/P8 primers, and our methods clearly showed high success rate of molecular sexing from non-invasive samples. These molecular tools open the possibilities for genetic studies using non-invasive samples collected from a mixed-species aggregation containing bean geese and white-fronted geese.

Genetic composition of communal roosts of the Eurasian Magpie (Pica pica) inferred from non-invasive samples.

Many animal species form communal roosts in which they aggregate and sleep together. Several benefits of communal roost have been suggested, but due to lack of data on relatedness among group members, it is unknown whether these benefits can be amplified by the formation of kin-based communal roosts. We investigate the genetic composition of two winter roosts of Eurasian Magpies (Pica pica), using microsatellite markers on non-invasive samples. Using permutation tests by reshuffling the alleles presented in the roosts, we determined that individuals in the communal roosts of magpies were not more related than expected by chance, suggesting that kinship may not be a driving force for the formation of communal roosts in magpies. However, the pairwise relatedness and estimated relationship based on a maximum likelihood approach revealed that the roosts involve both kin and non-kin. Relatedness coefficients varied widely within a roost, indicating that family subgroups form a small proportion of the total number of birds in a roost. Our results suggest that ecological benefits of communal roost in animals are sufficient for the evolution of communal roosts without any involvement of kinship.

Reformulation of Trivers-Willard hypothesis for parental investment.

The Trivers-Willard hypothesis (TWH) plays a central role in understanding the optimal investment strategies to male and female offspring. Empirical studies of TWH, however, yielded conflicting results. Here, we present models to predict optimal comprehensive multi-element parental strategies composed of primary sex ratio, brood size, resource allocation among offspring, and the resultant secondary sex ratio. Our results reveal that the optimal strategy depends on sex differences in the shape of offspring fitness function rather than in fitness variance. Also, the slope of the tangent line (through the origin) to the offspring fitness function can be used to predict the preferred offspring sex. We also briefly discuss links between the model and the empirical research. This comprehensive reformulation of TWH will offer a thorough understanding of multi-element parental investment strategies beyond the classical TWH.

Social behavior mediates the use of social and personal information in wild jays.

The factors favoring the evolution of certain cognitive abilities in animals remain unclear. Social learning is a cognitive ability that reduces the cost of acquiring personal information and forms the foundation for cultural behavior. Theory predicts the evolutionary pressures to evolve social learning should be greater in more social species. However, research testing this theory has primarily occurred in captivity, where artificial environments can affect performance and yield conflicting results. We compared the use of social and personal information, and the social learning mechanisms used by wild, asocial California scrub-jays and social Mexican jays. We trained demonstrators to solve one door on a multi-door task, then measured the behavior of naïve conspecifics towards the task. If social learning occurs, observations of demonstrators will change the rate that naïve individuals interact with each door. We found both species socially learned, though personal information had a much greater effect on behavior in the asocial species while social information was more important for the social species. Additionally, both species used social information to avoid, rather than copy, conspecifics. Our findings demonstrate that while complex social group structures may be unnecessary for the evolution of social learning, it does affect the use of social versus personal information.