Estimation of diet in extinct raccoon dog species by the molar ratio method

Estimation of the dietary habits of extinct species using morphological traits has been attempted in numerous studies; however, previous methods have encountered several difficulties, such as requiring specialized equipment. In this study, we describe an easy quantitative method for estimating the dietary habits, and apply it to extinct raccoon dogs (Nyctereutes) species (Carnivora, Mammalia). The method is based on the lower molar ratios (M₂/M₁ size) that reflect the species diet (carnivorous and omnivorous tendencies) in Canidae. Among the species statistically compared, Nyctereutes sinensis showed a lower M₂/M₁ score similar to that of Nyctereutes procyonoides albus (Hokkaido, Japan), whereas Nyctereutes tingi had a higher M₂/M₁ score similar to that of Nyctereutes procyonoides viverrinus (Honshu and Kyushu, Japan). These scores suggest that the diets of N. sinensis and N. tingi were similar to those of N. p. albus (relatively carnivorous) and N. p. viverrinus (relatively omnivorous), respectively. Other extinct raccoon dogs also showed varied M₂/M₁ score, suggesting dietary difference. These results suggest that raccoon dogs underwent dietary transitions or exhibited dietary plasticity during evolution, while their range of diets might have remained the same as those of different populations of extant species Nyctereutes procyonoides.     

Influence of premolar extraction or non-extraction orthodontic therapy on the angular changes of mandibular third molars

AimTo compare the angular changes of the third molars relative to the occlusal plane and to the second molar long axis in extraction group and compare these changes with a non extraction group.Materials and methodsThe study included pre and post treatment panoramic radiograph records of 90 subjects treated by first premolar extractions and 90 subjects who had been treated with non extraction orthodontic therapy (n = 90). Two angular variables were measured. Firstly, the angle between the long axis of the third molar and the occlusal plane (M3–OP) and secondly, the angle between the long axis of the third molar and the long axis of the second molar (M3–M2). Data were analyzed by paired and student’s t-test.ResultThe analyzed data to assess the changes in the third molar angulation from pretreatment to post treatment did not vary significantly in both the groups (p < 0.05). Both the groups showed decreased angular values. The M3–OP angular difference was (−7.3 ± 2.45) in extraction group as compared to (−5.85 ± 1.77) in non extraction group. The M3–M2 angular difference of (−4.26 ± 3.11) in extraction group and (−2.98 ± 1.74) in non-extraction group was observed.ConclusionExtraction of premolars did not demonstrate considerable changes on the angulation of the third molars. The factors other than premolar extractions may influence the angulation of the third molars.     

第三臼齿退化及其在人类演化上的意义

对第三臼齿退化在世界范围内各人类群体分类数据的分析表明：人类第三臼齿先天缺失是伴随整个人类进化而发生的牙齿退化现象的一部分,这一特片在居住于不同的地理区域的人类始发的时间及增加的速率不尽一致。     

Ionic volumes in solution

The volumetric properties of electrolytes in solutions indicate the interactions of the constituent ions with their environment: the solvent and other ions. The interactions with the solvent alone are manifested at infinite dilution by the standard partial molar volume, V(infinity)(salt), obtained from density measurements. To study the interactions, it is necessary to split V(infinity)(salt) into the additive ionic contributions, V(infinity)(ion), using an extra-thermodynamic assumption. Values of V(infinity)(ion) for small ions depend cardinally on the electrostriction of the solvent that can be obtained from an iterative shell-by-shell calculation from a continuum model of the solvent. The solvent shrinkage per mol of ions is DeltaV(el)(ion)<0. Also, the molar electrostriction of the solvent S, DeltaV(el)(S)<0, is calculable. The ratio DeltaV(el)(ion)/DeltaV(el)(S)=n(infinity) is the solvation number of the ion in S at infinite dilution. The calculated V(infinity)(ion)(calc) are compared with the experimental values, showing good agreement for many univalent ions in both single solvents and in some binary solvent mixtures, where no appreciable preferential solvation takes place. Ion pairing sets in under certain circumstances of ionic charge and solvent permittivity. The difference DeltaV(ip)=V(ip)(infinity)-[V(infinity)(+)+V(infinity)(-)]>0 is obtained experimentally from the pressure derivative of the association constant. The ratio Deltan(ip)=DeltaV(ip)/DeltaV(el)(S) represents the number of solvent molecules released to the bulk on ion pairing by the diminution of the electrostriction.     

How to measure and predict the molar absorption coefficient of a protein.

The molar absorption coefficient, epsilon, of a protein is usually based on concentrations measured by dry weight, nitrogen, or amino acid analysis. The studies reported here suggest that the Edelhoch method is the best method for measuring epsilon for a protein. (This method is described by Gill and von Hippel [1989, Anal Biochem 182:319-326] and is based on data from Edelhoch [1967, Biochemistry 6:1948-1954]). The absorbance of a protein at 280 nm depends on the content of Trp, Tyr, and cystine (disulfide bonds). The average epsilon values for these chromophores in a sample of 18 well-characterized proteins have been estimated, and the epsilon values in water, propanol, 6 M guanidine hydrochloride (GdnHCl), and 8 M urea have been measured. For Trp, the average epsilon values for the proteins are less than the epsilon values measured in any of the solvents. For Tyr, the average epsilon values for the proteins are intermediate between those measured in 6 M GdnHCl and those measured in propanol. Based on a sample of 116 measured epsilon values for 80 proteins, the epsilon at 280 nm of a folded protein in water, epsilon (280), can best be predicted with this equation: epsilon (280) (M-1 cm-1) = (#Trp)(5,500) + (#Tyr)(1,490) + (#cystine)(125) These epsilon (280) values are quite reliable for proteins containing Trp residues, and less reliable for proteins that do not. However, the Edelhoch method is convenient and accurate, and the best approach is to measure rather than predict epsilon.     

Reduction index of the upper M2 in marmosets

Marmosets have reduced second molars of which size and shape are varied in different species. Mesiodistal and buccolingual diameter of the first and second upper molars in 16 species were measured, and molar area (molar rectangle) and M2 reduction index were calculated by the equation,R=(M2 area/M1 area) × 100. This index ranged from 36.1 inSaguinus oedipus geoffroyi to 70.6 which was the largest found inCebuella pygmaea. Species ofSaguinus showed relatively wide variation as well as a consistantly smaller index. The index forCallithrix registered around 60 andLeontopithecus rosalia was positioned within this genus. There was no relationship between this index and body size of each form. The sizes of the first molar and second molar may not significantly correlate either with body size across species, becauseLeontopithecus rosalia had exceptionally large molars for its body size and contrarily genusSaguinus had relatively small molars. When the shape of the mandible was expressed as length/width ratio, the reduction index significantly correlate with this ratio in genusSaguinus andCallithrix, indicating that longer jaw in shape had relatively large M2. The reduction indices of two possible subspecies,S. oedipus geoffroyi andS. o. oedipus, were 36.1 and 47.3, respectively. This difference suggested that there was a difference in diet or function of jaw apparatus beyond subspecies level.     

Dental topography and diets of four old world monkey species

Dental topographic analysis allows comparisons of variably worn teeth within and between species to infer relationships between dental form and diet in living primates, with implications for reconstructing feeding adaptations of fossil forms. Although analyses to date have been limited mainly to the M₂s of a few primate taxa, these suggest that dental topographic analysis holds considerable promise. Still, larger samples including a greater range of species and different tooth types are needed to determine the potential of this approach. Here we examine dental topography of molar teeth of Cercocebus torquatus (n=48), Cercopithecus campbelli (n=50), Colobus polykomos (n=50), and Procolobus badius (n=50). This is the first such study of large samples of Old World monkeys, and the first to include analyses of both M₁s and M₂s. Average slope, relief, and surface angularity were computed and compared among tooth types, wear stages, and species. Results suggest that (1) data for M₁s and M₂s cannot be compared directly; (2) slope and relief decline with wear on M₂s of all taxa, and M₁s of the colobines, whereas angularity does not generally change except in the most worn specimens; and (3) folivorous colobines tend to have more sloping surfaces and more relief than do frugivorous cercopithecines, though angularity does not clearly separate taxa by diet. Am. J. Primatol. 71:466–477, 2009. © 2009 Wiley‐Liss, Inc.     

Molecular Characteristics of Bovine Serum Albumin-Dextran Conjugates

Bovine serum albumin (BSA)-dextran conjugates were prepared by using the Maillard reaction; depending on the ratio of dextran to BSA used, about 0.5–1 mol of dextran could be bound to 1 mol of native BSA. SDS–PAGE patterns revealed that BSA and dextran had been covalently bonded. Structural analyses by fluorescence spectroscopy and circular dichroism indicated that the BSA surface in each conjugate was covered with dextran without any great disruption of the native conformation. The conjugates could be grouped into two fractions on the basis of the weight-average molecular mass measured: the main fraction at 1.95–2.35×10⁵ g/mol and a less-abundant fraction with aggregates greater than 1.50×10⁶ g/mol. High-performance size-exclusion chromatography in conjunction with multi-angle laser light scattering detection revealed that the BSA-dextran conjugates prepared by using the Maillard reaction had various molar masses and radii.     

Differences in molar wear gradient between adult macaques and langurs

Interspecific differences in the amount and form of molar wear in nonhuman primates are only beginning to be documented and understood. The purpose of this study was to look at the wear gradient between M₁ and M₂ in a sample of macaques and langurs to determine if differences in wear gradient could be related to differences in diet. A skeletal collection of wild shot Macaca fascicularis, Presbytis cristata, and Presbytis rubicunda from the Museum of Comparative Zoology at Harvard University was examined using photogrammetric techniques. X, Y, and Z coordinates were used to compute areas of dentin exposure on the buccal occlusal surfaces of M₁ and M₂. The relationship between these variables was examined using Bartlett’s three-group method and least-squares regression. Interspecific comparisons of the resultant y intercepts indicate that (I) M. fascicularis (as compared with P. cristata or P.) has more dentin exposed on M₁ when there is none exposed on M₂, and (2) P. cristata (as compared with P. rubicunda) has more dentin exposed on M₁ when there is none exposed on M₂. Factors that might be responsible for these differences are (a) differences in dentin/enamel structure, (b) differences in molar eruption timing, and (c) differences in behavior. An unusual intercusp sequence of dentin exposure in the langurs makes precise interpretations difficult. However, at the present time, behavioral differences among the species deserve further consideration as a cause of the observed differences in molar wear gradient.     

拔除下颌第三磨牙对下颌角区形态影响的CBCT 研究

目的:探讨下颌第三磨牙的拔除会否造成下颌角区骨骼形态的变化以及这种变化对面型的影响。方法:30例因矫治需要拔除下颌第三磨牙的成人正畸患者,在拔牙前和拔牙后6个月拍摄CBCT片,采用三维测量软件mimics10.01测量下颌第三磨牙所在的下颌角区牙槽骨骨质的宽度、高度和长度,利用SPSS18.0统计软件分析前后数值有无差异。结果:下颌第三磨牙拔除前后下颌角区骨质宽度和高度减小,差异有统计学意义(P<0.05),下颌角区骨质前后向长度未见明显差异。结论:拔除下颌第三磨牙能从一定程度上减小下颌角区骨质高度和宽度,但是前后向长度度基本没有变化。     

Does the angulation of the mandibular third molar influence the fragility of the mandibular angle after trauma to the mandibular body? A three-dimensional finite-element study

The relationship between mandibular third molar (M3) angulation and mandibular angle fragility is not well established. The aim of this study was to evaluate the impact of M3 angulation on the mandibular angle fragility when submitted to a trauma to the mandibular body region. A three-dimensional (3D) mandibular model without M3 (Model 0) was obtained by means of finite-element analysis (FEA). Four models were generated from the initial model, representing distoangular (Model D), horizontal (Model H), mesioangular (Model M) and vertical (Model V) angulations. A blunt trauma with a magnitude of 2000 N was applied perpendicularly to the sagittal plane in the mandibular body. Maximum principal stress (P_max) (tensile stress) values were calculated in the bone. The lowest P_max stress values were noted in Model 0. When the M3 was present extra stress fields were found around marginal bone of second molar and M3. Comparative analysis of the models with M3 revealed that the highest level of stress was found in Model V, whereas Model D showed the lowest stress values. The angulation of M3 affects the stress levels in the mandibular angle and has an impact on mandibular fragility. The mandibular angle becomes more fragile in case of vertical impaction when submitted to a trauma to the mandibular body region.     

Photobiomodulation increases intrusion tooth movement and modulates IL‐6, IL‐8 and IL‐1β expression during orthodontically bone remodeling

This study investigated the effects of photobiomodulation (PBM) on upper molar intrusion movement, regarding acceleration of orthodontic movement and its molecular effects. The sample consisted of 30 patients with indication of tooth intrusion for oral rehabilitation. Teeth were divided into three different groups: G1 (n = 10) pre‐molars without force or laser application (control); G2 (n = 10) upper molar intrusion; and G3 (n = 10) upper molar intrusion and PBM. On PBM treated molars, the teeth were irradiated with a low‐power diode laser (808 nm, 100 mW), receiving 1 J per point, density of 25 J/cm², with application of 10 s per point, 10 points (5 per vestibular and 5 per palatal region). Orthodontic force of intrusion applied every 30 days and PBM was performed immediately, 3 and 7 days after force application for 3 months. Gingival crevicular fluid was collected at the same time periods as the laser applications and interleukins (IL) 1‐β, ‐6 and ‐8 were evaluated by enzyme‐linked immunosorbent assay. Clinical measures were performed monthly to verify the amount of intrusion. The levels of IL‐6, IL‐8 and IL‐1β increased under orthodontic force (G2 and G3) when compared to control group (G1), however, the cytokines levels were significantly higher after PBM (G3). The mean intrusion velocity was 0.26 mm/month in the irradiated group (G3), average duration of 8 months vs 0.17 mm/month for the non‐irradiated group (G2), average duration of 12 months. This study suggests that PBM accelerates tooth movement during molar intrusion, due to modulation of IL‐6, IL‐8 and IL‐1β during bone remodeling.      

Morphological variation and covariation in mandibular molars of platyrrhine primates

Molars are highly integrated biological structures that have been used for inferring evolutionary relationships among taxa. However, parallel and convergent morphological traits can be affected by developmental and functional constraints. Here, we analyze molar shapes of platyrrhines in order to explore if platyrrhine molar diversity reflects homogeneous patterns of molar variation and covariation. We digitized 30 landmarks on mandibular first and second molars of 418 extant and 11 fossil platyrrhine specimens to determine the degree of integration of both molars when treated as a single module. We combined morphological and phylogenetic data to investigate the phylogenetic signal and to visualize the history of molar shape changes. All platyrrhine taxa show a common shape pattern suggesting that a relatively low degree of phenotypic variation is caused by convergent evolution, although molar shape carries significant phylogenetic signal. Atelidae and Pitheciidae show high levels of integration with low variation between the two molars, whereas the Cebinae/Saimiriinae, and especially Callitrichinae, show greater variation between molars and trend toward a modular organization. We hypothesize that biomechanical constraints of the masticatory apparatus, and the dietary profile of each taxon are the main factors that determine high covariation in molars. In contrast, low molar shape covariation may result from the fact that each molar exhibits a distinct ecological signal, as molars can be exposed to distinct occlusal loadings during food processing, suggesting that different selective pressures on molars can reduce overall molar integration.     

Diet reconstruction in antebellum Baltimore: Insights from dental microwear analysis

Construction in the City of Baltimore during 1996 led to the recovery of human skeletal remains dating from 1792 to 1856. Historical research indicates that the skeletal remains come from two adjacent graveyards: Christ's Church Episcopalian Cemetery and the Potters Field East. The different socioeconomic status of the internees in each cemetery suggests the possibility of marked contrasts in lifestyle, health, and diet. To shed further light on these possibilities, analyses of microscopic wear patterns on teeth, or dental microwear analyses, were undertaken. A sample from Spanish Florida was used to help interpret the results. Epoxy casts of incisor and molar teeth were placed in an SEM and photomicrographs of clean wear facets were taken. The photomicrographs were digitized using the software package Microware 4.02. Statistical analyses of rank transformed data consisted of single‐factor ANOVA, followed by post hoc tests. No significant differences were found between Christ's Church and Potters Field East samples for any of the variables examined in either molar or incisor teeth. However, differences between each Baltimore sample and the La Florida samples give suggestions of possible diet differences in antebellum Baltimore. The mosaic of differences between the Baltimore and La Florida samples probably reflects the wide variety of foods available to antebellum Baltimoreans as well as the relative lack of abrasives in their diet. Am J Phys Anthropol, 2010. © 2009 Wiley‐Liss, Inc.     

“Measure my teeth and you'll know what I ate”: The molar ratio method and an updated interpretation of the diet of Nyctereutes sinensis (Carnivora,Canidae)

The molar ratio method presented by Acta Zoologica (98, 2016, 292) is a valid way to estimate the dietary differences between extant subspecies of the raccoon dog genus, Nyctereutes. Particularly, higher values of the molar ratio implies more omnivous diet than lower ones. With the same technique is possible to infer variations in the diet of extinct species. For the two Plio-Pleistocene fossil species Nyctereutes sinensis and Nyctereutes megamastoides, the authors estimate a more carnivorous diet for the latter in comparison to the former that has much higher values. This fact contrast with the morphological features of these two highly comparable species, often considered as morphotypes of the same species. Thanks to the revision of a large sample of N. sinensis from Chinese localities of the Yushe Basin (Shanxi Province), new scores for this species have been calculated. The results presented here confirms a strong adaptation to an omnivorous diet, as emerged from morphofunctional evidence in recent literature.     

Beneficial effects of combination of P and Zn for green gram (Phaseolus aureus L.)

Summary Dicalcium phosphate dihydrate and potassium dihydrogen phosphate were applied to calcareous soil in combination with zinc sulphate in the molar ratio of 100∶0, 100∶1, 100∶2 and 100∶4. Increasing addition of zinc sulphate into P sources gradually increased KCl (0.01M) soluble P and Zn, NaHCO₃ (0.5M, pH 8.5) extractable P and DTPA extractable Zn from soil and grain and straw yields of green gram.     

Isentropic and isothermal compressibilities of the backbone glycyl group of proteins in aqueous solution

The partial molar isentropic compressibilities at infinite dilution, K(S,2)(o), have been determined for the peptides serylglycine, serylglycylglycine and serylglycylglycylglycine in aqueous solution at 25 degrees C. The partial molar volumes at infinite dilution, V(2)(o), have also been determined for these peptides in aqueous solution at the temperatures 15, 30 and 40 degrees C. These results, along with those obtained previously at 25 degrees C, were used to derive the partial molar exansibilities, E(2)(o), of the peptides at 25 degrees C, which in turn were used to convert the isentropic compressibilities into the partial molar isothermal compressibilities at infinite dilution, K(T,2)(o). These K(S,2)(o) and K(T,2)(o) results were used to obtain the partial molar compressibilities of the glycyl group CH(2)CONH at 25 degrees C. The results are compared with those obtained using data for other series of peptides of sequence ala(gly)(n), n=1-4, and (gly)(n), n=2-5.     

Earliest South American paucituberculatans and their significance in the understanding of ‘pseudodiprotodont’ marsupial radiations

We describe the oldest Paucituberculata marsupials, from the La Barda and Las Flores localities (Argentina; Late Palaeocene, and Early–Middle Eocene), as well as from the Itaboraí Basin (Brazil; Late Palaeocene). The new taxa are represented by very scarce, although well‐preserved, dental remains. A parsimony analysis was performed in order to evaluate the phylogenetic affinities of these taxa. Representatives of both Riolestes capricornicus gen. et sp. nov. and Bardalestes hunco gen. et sp. nov. appear to be basal paucituberculatans, and their molar features give clues on the early evolution of the representatives of this order. Within the Paucituberculata we recognize two major clades: Caenolestoidea and Palaeothentoidea. We conclude that ‘pseudodiprotodont’ marsupials of the traditional literature (i.e. Polydolopimorphia + Paucituberculata) do not form a natural group. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155 , 867–884.     

Can tooth differentiation help to understand species coexistence? The case of wood mice in China

Five wood mice Apodemus species occur across China, in allopatry but also in sympatry up to cases of syntopy. They all share a similar external appearance, similar habitats of grasslands and forests and a generalist feeding behaviour. This overall similarity raises questions about the mechanisms insuring competition avoidance and allowing the coexistence of the species. In this context, a morphometric analysis of two characters related to feeding (mandible and molar) addressed the following issues: (1) Were the species actually different in size and/or shape of these characters, supporting their role in resource partitioning? (2) Did this pattern of phenotypic divergence match the neutral genetic differentiation, suggesting that differentiation might have occurred in a former phase of allopatry as a result of stochastic processes? (3) Did the species provide evidence of character displacement when occurring in sympatry, supporting an ongoing role of competition in the interspecific divergence? Results evidenced first that different traits, here mandibles and molars, provided discrepant pictures of the evolution of the Apodemus group in China. Mandible shape appeared as prone to vary in response to local conditions, blurring any phylogenetic or ecological pattern, whereas molar shape evolution appeared to be primarily driven by the degree of genetic differentiation. Molar size and shape segregated the different species in the morphospace, suggesting that these features may be involved in a resource partitioning between Apodemus species. The morphological segregation of the species, likely achieved by processes of differentiation in isolation promoted by the complex landscape of China, could contribute to competition avoidance and hence explain why no evidence was found of character displacement.