Post-mortem wear as indicator of taphonomic processes affecting enamel surfaces of hominin teeth from Laetoli and Olduvai (Tanzania): implications to dietary interpretations

The buccal microwear pattern of premolar and molar teeth has been linked to the composition of the ingested diet in human populations, both extant and fossil. However, numerous enamel surfaces observed for microwear analyses show microscopic damage that can be attributed to post-mortem taphonomic processes, not related to dietary habits. Post-depositional processes may greatly affect enamel surfaces, occasionally hindering dietary reconstructions based on dental microwear patterns. The present study analyses the damage patterns that can be observed on fossil Hominin teeth from the sites of Laetoli and Olduvai (Tanzania) to differentiate between ante-mortem and post-mortem processes. The results obtained show that post-mortem wear can be easily differentiated from ante-mortem abrasion for its distinct effects, mainly consisting of obliteration of enamel features. The frequency of abraded surfaces in the samples studied is considerably high. Despite the great antiquity of the remains studied, patches of well preserved enamel can still be distinguished in a number of teeth. Well preserved enamel surfaces can be discriminated for their polished appearance and the presence of distinct microwear features

Tooth replication techniques, SEM imaging and microwear analysis in Primates: methodological obstacles

Dental microwear analyses are among the most significant techniques though which a researcher can make dietary and ecological inferences from primate fossil specimens. Hard particles, such as plant phytoliths or silica-base sands, can scratch tooth enamel surfaces during food mastication producing a dietary specific pattern of microwear on the enamel surface. The density, axis length and orientation of microwear features, either striations or pits, are highly informative of dietary habits in both extant and fossil primates. The analysis of tooth enamel surfaces requires the use of scanning electron microscopy (SEM) techniques, because of its high resolution power, including gold-coating of teeth for observation. Problems arise when specimens to be analysed are unique and there is no possibility of a direct observation with an environmental microscope. Negative moulds must then be made and silicone-base components are indicated for high quality replication of enamel surfaces. A positive cast needs to be obtained, and epoxy-base resins are frequently used for their good quality and durability. However, successive silicon and epoxy replications result in the loosing of surface detail and precision. Surface observation errors can also be caused be the SEM technology itself, especially if back-scattered electrons are used instead of secondary electrons for maximizing the topographical information of enamel images. This paper reviews the most commonly used methodological approaches to tooth moulding and casting, comparing SEM micrographs of casts with actual tooth surfaces, and contrasting the reliability of SEM images for dietary interpretation of tooth microwear in both extant and fossil primates

Testing dietary hypotheses of East African hominines using buccal dental microwear data

Abstract There is much debate on the dietary adaptations of the robust hominin lineages during the Pliocene-Pleistocene transition. It has been argued that the shift from C3 to C4 ecosystems in Africa was the main factor responsible for the robust dental and facial anatomical adaptations of Paranthropus taxa, which might be indicative of the consumption of fibrous, abrasive plant foods in open environments. However, occlusal dental microwear data fail to provide evidence of such dietary adaptations and are not consistent with isotopic evidence that supports greater C4 food intake for the robust clades than for the gracile australopithecines. We provide evidence from buccal dental microwear data that supports softer dietary habits than expected for P. aethiopicus and P. boisei based both on masticatory apomorphies and isotopic analyses. On one hand, striation densities on the buccal enamel surfaces of paranthropines teeth are low, resembling those of H. habilis and clearly differing from those observed on H. ergaster, which display higher scratch densities indicative of the consumption of a wide assortment of highly abrasive foodstuffs. Buccal dental microwear patterns are consistent with those previously described for occlusal enamel surfaces, suggesting that Paranthropus consumed much softer diets than previously presumed and thus calling into question a strict interpretation of isotopic evidence. On the other hand, the significantly high buccal scratch densities observed in the H. ergaster specimens are not consistent with a highly specialized, mostly carnivorous diet; instead, they support the consumption of a wide range of highly abrasive food items

Analysis of factors involved in the teaching-learning system in a state of emergency

[EN] The present work arises as a consequence of the current situation that is being experienced worldwide due to COVID 19 and the repercussions it has had on households, especially in the adaptation to new forms of work and teaching, affecting social, economic and cultural aspects. The pandemic has hit the poor and vulnerable hardest, and could push millions more people into poverty, especially in Latin American countries. In this context, in Ecuador, due to the COVID-19 pandemic, extreme poverty is likely to increase dramatically. The study focuses on the application of different multivariate techniques, such as, Discriminant Analysis, Cluster Analysis and ROC curve,to develop a multidimensional poverty index based on non-monetary household resources such as equipment and basic services. With the combined use of the proposed techniques, an indicator was obtained that can serve as a tool for measuring the factors that can affect extreme poverty in Ecuador and it can be used to introduce continuous improvement actions in the resource assigments.Pérez Avellaneda, A.; Cueva, D.; Martínez-Gómez, M. (2022). Analysis of factors involved in the teaching-learning system in a state of emergency. En 4th International Conference on Advanced Research Methods and Analytics (CARMA 2022). Editorial Universitat Politècnica de València. 288-288. http://hdl.handle.net/10251/18970828828

Nota metodológica: Alteración del patrón de microestriación dentaria por el efecto wrinkle.

Se describe el efecto wrinkle observado por primera vez sobre moldes dentarios realizados con resinas epoxy y metalizados en oro para su observación mediante microscopía electrónica de barrido (SEM). Con el fin de determinar en qué medida puede afectar al análisis del patrón de microestriación vestibular, se analizan dos muestras dentales de tres especies de Hominoideos, una de ellas incluyendo moldes con presencia de"aguas" relacionadas con el proceso de metalización. Se observa un descenso marcado de la variabilidad del patrón de microestriación dentaria anque las diferencias entre las dos muestras por especie no son estadísticamente significativas. El efecto wrinkle reduce significativamente el porcentaje de clasificación correcta de las especies analizadas a partir del patrón de microestriación y rugosidad dental utilizando un Análisis Discriminante. Se aconseja evitar la inclusión de las muestras afectadas por aguas en los estudios del patrón de microestriación dentaria

Tooth crown size and dentine exposure in Australopithecus and early Homo: testing hypotheses of dietary related selective preasures

Preliminary analyses of total crown area and dentine exposure surfaces in a sample of hominid teeth seem to indicate that a significant correlation between tooth size and occlusal abrasion occurs, most probably related to dental occlusal function rather than to normal food mastication. Dental microwear on the buccal surfaces of teeth might be determined by foodstuffs abrasiveness whereas occlusal gross wear could be more dependent on either cultural practices with teeth or food processing. The effect of occlusal function of teeth on diet determination and ecological interpretation of hominid behaviour is dealt with, considering that habitat occupation and diet might affect differently and distinctly to tooth wear rate patterns

New evidence and interpretation of subvertical grooves in eandertal teeth from Cueva de Sidrón (Spain) and Figueira Brava (Portugal)

Interproximal tooth wear is caused by tooth-to-tooth rubbing that results in the formation of flat wear surfaces characterized by an intense pattern of enamel pitting caused by prism-plucking. The rate of wear of such surfaces depends on the forces involved in food processing and chewing. In some instances, the interproximal wear facets, mainly of molar teeth, show a number of subvertical grooves with a nearly vertical direction. These grooves are mostly present in Neanderthal teeth, but have also been described in some African fossil teeth and in European Homo heidelbergensis, as well as in several modern hunter-gatherer populations, such as Australian Aborigines. Subvertical grooves have seldom been attributed to taphonomic processes, although most probably they are caused by natural biomechanical processes during mastication of hard objects included in the diet. They have also been associated to acidic dietary habits given their radial disposition and their inter-digitalisation. The present study analyses the subvertical grooves observed in the Neanderthal dentition of Cueva de Sidrón (Spain). Comparisons are made with the similar interproximal grooves pattern observed in the Neanderthal specimen from Figueira Brava (Portugal) and some remains of H. heidelbergensis from Sima de los Huesos (Spain). Other cases have been described for the Neanderthal sites of Genay and Le Fate (France). The results obtained allow discarding a post-mortem origin of these structures, the most probable cause of the subvertical grooves being natural biomechanical chewing processes combined with some dietary habits indicative of hard plant foods ingestion

Activation in the family of Candida rugosa isolipases by polyethylene glycol

Disponible en: http://www.xtal.iqfr.csic.es/publications/jmolcat2005.pdfWe have investigated activation of two isoenzymes (lip1 and lip3) from Candida rugosa in polyethylene glycol (PEG) media. Aqueous solutions of PEG 8000 and 20,000 activate lip3 but not lip1 from C. rugosa. Maximum activation (260%) of lip3 requires 6 h of pre-incubation with PEG 8000 (4%, w/v). PEG seems to shift the equilibrium between the open and the closed forms of lip3 towards the active conformation. Inhibition experiments demonstrate that ligands have easier access to the lip3 active site than to the lip1 active site, both in the presence and the absence of PEG. The presence of PEG in the crystallization medium is responsible for reported differences in the crystal structures of lip1 and lip3. A comparative analysis of crystallographic models of lip1 and lip3 suggests a role for PEG in activation of lip3 and further stabilization of the activated/open form via dimerization in aqueous media.This work has been financed by the Spanish CICYT (PB92/0495 and BIO 96/0837). A predoctoral fellowship for M.F.P. was provided by the Autonomous Community of Madrid (Spain).Peer reviewe

New Insights Into Sunflower (Helianthus annuus L.) FatA and FatB Thioesterases, Their Regulation, Structure and Distribution

Sunflower seeds (Helianthus annuus L.) accumulate large quantities of triacylglycerols (TAG) between 12 and 28 days after flowering (DAF). This is the period of maximal acyl-acyl carrier protein (acyl-ACP) thioesterase activity in vitro, the enzymes that terminate the process of de novo fatty acid synthesis by catalyzing the hydrolysis of the acyl-ACPs synthesized by fatty acid synthase. Fatty acid thioesterases can be classified into two families with distinct substrate specificities, namely FatA and FatB. Here, some new aspects of these enzymes have been studied, assessing how both enzymes contribute to the acyl composition of sunflower oil, not least through the changes in their expression during the process of seed filling. Moreover, the binding pockets of these enzymes were modeled based on new data from plant thioesterases, revealing important differences in their volume and geometry. Finally, the subcellular location of the two enzymes was evaluated and while both possess an N-terminal plastid transit peptide, only in FatB contains a hydrophobic sequence that could potentially serve as a transmembrane domain. Indeed, using in vivo imaging and organelle fractionation, H. annuus thioesterases, HaFatA and HaFatB, appear to be differentially localized in the plastid stroma and membrane envelope, respectively. The divergent roles fulfilled by HaFatA and HaFatB in oil biosynthesis are discussed in the light of our data.España MINECO y FEDER Projects AGL2014- 53537-R y AGL2017-83449-

Dealing with water conflicts: a comprehensive review of mcdm approaches to manage freshwater ecosystem services

This paper presents a comprehensive review of the application of Multiple-Criteria Decision-Making (MCDM) approaches exclusively to water-related freshwater ecosystem services. MCDM analysis has been useful in solving conflicts and it works well in this framework, given the serious conflicts historically associated with water use and the protection of freshwater ecosystems around the world. In this study, we present a review of 150 papers that proposed the use of MCDM-based methods for the social, economic, or ecological planning and management of water ecosystem services over the period 2000–2020. The analysis accounts for six elements: ecosystem service type, method, participation, biogeographical realm, waterbody type, and problem to solve. A Chi-square test was used to identify dependence between these elements. Studies involving the participation of stakeholder groups adopted an integrated approach to analysing sustainable water management, considering provisioning, regulating, and cultural services. However, such studies have been in decline since 2015, in favour of non-participatory studies that were strictly focused on ecological and provisioning issues. Although this reflects greater concern for the health of freshwater ecosystems, it is a long way removed from the essence of ecosystem services, which entails an integrated approach to the interrelationships between hydrology, landscapes, ecology, and humans.The authors thanks the UNESCO UNED-URJC Chair in Water and Peace institutional coverage to the development of this study.info:eu-repo/semantics/publishedVersio