Search results for "Mola"
showing 10 items of 1216 documents
The way wear goes: phytolith-based wear on the dentine–enamel system in guinea pigs (Cavia porcellus)
2019
The effect of phytoliths on tooth wear and function has been contested in studies of animal–plant interactions. For herbivores whose occlusal chewing surface consists of enamel ridges and dentine tissue, the phytoliths might particularly erode the softer dentine, exposing the enamel ridges to different occlusal forces and thus contributing to enamel wear. To test this hypothesis, we fed guinea pigs (Cavia porcellus; n = 36 in six groups) for threeweeks exclusively on dry or fresh forage of low(lucerne), moderate (fresh timothy grass) or very high (bamboo leaves) silica content representing corresponding levels of phytoliths. We quantified the effect of these treatments with measuremen…
Morphological modularity and assessment of developmental processes within the vole dental row (Microtus arvalis, Arvicolinae, Rodentia).
2009
10 pages; International audience; Knowledge of mammalian tooth formation is increasing, through numerous genetic and developmental studies. The prevalence of teeth in fossil remains has led to an intensive description of evolutionary patterns within and among lineages based on tooth morphology. The extent to which developmental processes have influenced tooth morphologies and therefore the role of these processes in these evolutionary patterns are nonetheless challenging. Recent methodological advances have been proposed allowing the inference of developmental processes from adult morphologies and the characterization of the degree of developmental integration/modularity of morphological tr…
When less means more: evolutionary and developmental hypotheses in rodent molars.
2012
10 pages; International audience; Tooth number in rodents is an example of reduction in evolution. All rodents have a toothless diastema lacking canine and most premolars present in most other mammals. Whereas some rodent lineages retained one premolar (p4), many others lost it during evolution. Recently, an 'inhibitory cascade' developmental model (IC) has been used to predict how the first molar (m1) influences the number and relative sizes of the following distal molars (m2 and m3). The model does not, however, consider the presence of premolars, and here we examine whether the premolar could influence and constrain molar proportions during development and evolution. By investigating a l…
Evolution of mammal tooth patterns: new insights from a developmental prediction model.
2009
14 pages.; International audience; The study of mammalian evolution is often based on insights into the evolution of teeth. Developmental studies may attempt to address the mechanisms that guide evolutionary changes. One example is the new developmental model proposed by Kavanagh et al. (2007), which provides a high-level testable model to predict mammalian tooth evolution. It is constructed on an inhibitory cascade model based on a dynamic balance of activators and inhibitors, regulating differences in molar size along the lower dental row. Nevertheless, molar sizes in some mammals differ from this inhibitory cascade model, in particular in voles. The aim of this study is to point out arvi…
Dental wear proxy correlation in a long-term feeding experiment on sheep ( Ovis aries )
2021
Dietary reconstruction in vertebrates often relies on dental wear-based proxies. Although these proxies are widely applied, the contributions of physical and mechanical processes leading to meso- and microwear are still unclear. We tested their correlation using sheep ( Ovis aries , n = 39) fed diets of varying abrasiveness for 17 months as a model. Volumetric crown tissue loss, mesowear change and dental microwear texture analysis (DMTA) were all applied to the same teeth. We hereby correlate: (i) 46 DMTA parameters with each other, for the maxillary molars (M1, M2, M3), and the second mandibular molar (m2); (ii) 10 mesowear variables to each other and to DMTA for M1, M2, M3 and m2; and (…
Modular Wear Facet Nomenclature for mammalian post-canine dentitions
2017
Dental wear facets on the occlusal surface of premolars and molars are traces of their main function, the mastication and therefore reflect masticatory movements and also paramasticatory (i.e. non-dietary use of teeth) behavior. Here we present the Modular Wear Facet Nomenclature applicable to most mammalian dentitions. Topographic positions of wear facets in relation to the major cusps and crests of the teeth are used to designate the areas of the occlusal surface the facets occupy (e.g. their mesial, distal, lingual, or buccal position). Previous published systems for labeling wear facets have been inconsistent with each other. Therefore, we provide a synoptic review of the most widely-us…
Involvement of osmotic cell shrinkage on the proton extrusion rate in Saccharomyces cerevisiae
2001
Saccharomyces cerevisiae has been subjected to hyperosmotic shocks by using permeating (sorbitol, xylitol, glycerol, NaCl) and nonpermeating (PEG 600) solutes. The proton extrusion rate decreased as the osmotic pressure increased, whichever solute was used. However, the total inhibition of the cellular H+ extrusion depended on the solute used. A total inhibition was observed at about 20 MPa with glycerol, xylitol and sorbitol. With PEG 600, a total inhibition of extracellular acidification was obtained at 8.5 MPa. NaCl, with an extracellular pressure of 37.8 MPa (near saturation), did not completely inhibit the extracellular acidification. These results showed that the total inhibition of p…
Why all vole molars (Arvicolinae, Rodentia) are informative to be considered as proxy for Quaternary paleoenvironmental reconstructions.
2013
13 pages; International audience; Rodents are considered as a good model and as a good proxy to characterise Quaternary environments. Molars and incisors are the best-preserved remains and are found in abundance in the fossil record. Since several decades, the lower molars are mostly used for specific determinations. Instead of using qualitative and descriptive characters, morphometric methods provide now a general quantitative description of shape. Applying these new morphometric methods (outline analysis), we demonstrate that lower as well as upper molars are useful and efficient for palaeontological analyses within voles (Arvicolinae). Herein it is made evident that except the first lowe…
Active vanadate-sensitive H+ translocation in corn roots membrane vesicles and proteoliposomes
1988
Abstract A member fraction from corn roots which contains a vanadate-sensitive ATPase activity has been prepared. The specific activity at 38°C is between 3 and mol 12 μmol · min −1 · mg −1 , depending on the age of roots. Addition of ATP promotes a very rapid quenching of the fluorescence of 9-amino-6-chloro-3-methoxy-acridin (ACMA). Proton pumping exhibits a delayed sensitivity to vanadate but is strongly and instantaneously inhibited by the new inhibitor SW 26. Both proton pumping, measured by the initial quenching rate, and ATP hydrolysis show maximum activities at ATP concentrations in the millimolar range, but the apparent K m -value for hydrolysis is higher than that observed for pro…
The application of electroanalytical methods to determine affinity series of metal cations for functional biosorbent groups
2018
Abstract The affinity of the selected heavy metal cations: Mn 2 + , Ni 2 + , Cu 2 + , Zn 2 + , Cd 2 + , Pb 2 + and Na + , K + , Mg 2 + , Ca 2 + was determined for the functional groups located on the surface of leached barley middlings, so called Brewer's spent grain (BSG) – a by-product of the brewing industry. A simple method for determining the affinity series, with the use of a conductivity meter and a pH-meter, was described. It was demonstrated that the affinity of cations for the functional groups located on the surface of the BSG increases in the series: Na + + 2 + 2 + ≈ Zn 2 + 2 + ≈ Ca 2 + 2 + 2 + 2 + , and the series was determined by comparing concentrations expressed in gram e…