Jimena Barbeito-Andrés

Chronic Protein Restriction in Mice Impacts Placental Function and Maternal Body Weight before Fetal Growth

Mechanisms of resource allocation are essential for maternal and fetal survival, particularly when the availability of nutrients is limited. We investigated the responses of feto-placental development to maternal chronic protein malnutrition to test the hypothesis that maternal low protein diet produces differential growth restriction of placental and fetal tissues, and adaptive changes in the placenta that may mitigate impacts on fetal growth. C57BL/6J female mice were fed either a low-protein diet (6% protein) or control isocaloric diet (20% protein). On embryonic days E10.5, 17.5 and 18.5 tissue samples were prepared for morphometric, histological and quantitative RT-PCR analyses, which included markers of trophoblast cell subtypes. Potential endocrine adaptations were assessed by the expression of Prolactin-related hormone genes. In the low protein group, placenta weight was significantly lower at E10.5, followed by reduction of maternal weight at E17.5, while the fetuses became significantly lighter no earlier than at E18.5. Fetal head at E18.5 in the low protein group, though smaller than controls, was larger than expected for body size. The relative size and shape of the cranial vault and the flexion of the cranial base was affected by E17.5 and more severely by E18.5. The junctional zone, a placenta layer rich in endocrine and energy storing glycogen cells, was smaller in low protein placentas as well as the expression of Pcdh12, a marker of glycogen trophoblast cells. Placental hormone gene Prl3a1 was altered in response to low protein diet: expression was elevated at E17.5 when fetuses were still growing normally, but dropped sharply by E18.5 in parallel with the slowing of fetal growth. This model suggests that nutrients are preferentially allocated to sustain fetal and brain growth and suggests the placenta as a nutrient sensor in early gestation with a role in mitigating impacts of poor maternal nutrition on fetal growth.

Ontogenetic changes in cranial vault thickness in a modern sample of Homo sapiens.

This work assesses cranial vault thickness (CVT) ontogenetic changes using a computed tomography database to register thickness across multiple regions.

Measurement error of 3D cranial landmarks of an ontogenetic sample using Computed Tomography

BACKGROUND/AIM Computed Tomography (CT) is a powerful tool in craniofacial research that focuses on morphological variation. In this field, an ontogenetic approach has been taken to study the developmental sources of variation and to understand the basis of morphological evolution. This work aimed to determine measurement error (ME) in cranial CT in diverse developmental stages and to characterize how this error relates to different types of landmarks. MATERIAL AND METHODS We used a sample of fifteen skulls ranging from 0 to 31 years. Two observers placed landmarks in each image three times. Measurement error was assessed before and after Generalized Procrustes Analysis. RESULTS The results indicated that ME is larger in neurocranial structures, which are described mainly by type III landmarks and semilandmarks. In addition, adult and infant specimens showed the same level of ME. These results are specially relevant in the context of craniofacial growth research. CONCLUSION CT images have become a frequent evidence to study cranial variation. Evaluation of ME gives insight into the potential source of error in interpreting results. Neural structures present higher ME which is mainly associated to landmark localization. However, this error is irrespective of age. If landmarks are correctly selected, they can be analyzed with the same level of reliability in adults and subadults.

Technical note: Performance of semi and fully automated approaches for registration of 3D surface coordinates in geometric morphometric studies.

OBJECTIVES One of the biggest challenges in the study of complex morphologies is to adequately describe shape variation. Here, we assess how the random sampling of surface points automatically obtained performs, when compared with observer-guided sampling procedures, and also evaluate the effect of sliding surface points by bending energy and minimum Procrustes distance. MATERIAL AND METHODS Three datasets comprising structures with disparate levels of complexity and intrasample variation are as follows: mouse molars, mouse brains, and primate endocasts. Different configurations of 3D coordinates on curves and surfaces were digitized from MRI images and CT scans using semi and fully automated procedures. Shape variables were obtained by Generalized Procrustes Superpositions before and after sliding the pseudolandmarks. Multivariate analyses were used to summarize and compare shape variation. RESULTS For the primate endocast, the semiautomated and automated strategies yield similar ordinations of specimens. Conversely, the semiautomated strategy better discriminates molar shapes between mouse groups. Shape differences among specimens are not adequately represented by the PCs calculated with surface pseudolandmarks. This is improved when the points are converted into semilandmarks by a sliding criterion. DISCUSSION Surface semilandmarks automatically obtained from 3D models are promising although they should be used with some caution in complex structures. This approach can be taken as complementary of semiautomated procedures which perform better for assessing shape variation in localized traits previously selected while automated procedures are suitable in studies aimed at comparing overall variation in shape and when there is no previous information about highly variable anatomical regions.

Developmental covariation of human vault and base throughout postnatal ontogeny

In the present study, we analyzed postnatal ontogenetic integration among morphological traits of the human neurocranium. Particularly, the covariation between the vault and the base during postnatal life was assessed. Since the association between these regions may depend on the generalized change produced by allometry, we tested its effect on their covariation. On a sample of adults and subadults ranging from 0 to 31 years, 3D coordinates of neurocranial landmarks and semilandmarks were digitized and geometric morphometric technics were applied. Main aspects of shape variation were examined using Principal Components analysis. Covariation between the vault and the base was examined by Partial Least Squares analysis. According to our results, the vault and the base covary strongly during postnatal ontogeny and their relation depends largely on allometry. Two size variables were studied: centroid size, which was obtained from the recorded morphometric points, and endocranial volume, taken as an estimation of brain size. Although growing brain was found to be a developmental process that contributes to covariation among neurocranial traits, there would be other factors that exert their influence during ontogeny. These results lead to reconsider cranial morphological evolution taking into account the developmental constraints given by ontogenetic patterns of integration and reinforcing the idea that in human evolution a suite of relevant characters may be fuelled by few developmental processes.

An ontogenetic approach to facial variation in three Native American populations.

Various explanations have been formulated regarding high levels of craniofacial variation among Native American populations but the contribution of developmental processes to the establishment of these patterns of variation remains unknown. In this study, we compare facial morphology in ontogenetic series of three Native South American populations, one hunter-gatherer group and two farmer groups, in order to test the null hypothesis that indicates that the pattern of facial differentiation between populations does not change during ontogeny. If diet-related factors contribute to outline facial morphology, it is likely to find greater differences between hunter-gatherer and both farmer groups than between two groups of farmers and this differentiation is expected to increase with age, especially in those structures that are influenced by the mechanical load of mastication. According to our results, hunter-gatherers clearly differ from the two groups of farmers. Non-heritable factors linked to diet, such as nutritional content of food, may increase differentiation across ontogeny in some cases. However, as hunter-gatherers were clearly separated from farmer populations during entire postnatal ontogeny, an important proportion of size variation may not necessarily reflect eco-sensitive changes. Consequently, the hypothesis cannot be completely rejected.

Morphological asymmetries of mouse brain assessed by geometric morphometric analysis of MRI data

Mammalian brain has repeated structures at both sides of the median plane, although some asymmetries have been described even under normal conditions. Characterizing normal patterns of asymmetry in mouse brain is important to recognize features that depart from expected ranges in the most widely used mammalian model. Analyses on brain morphology based on magnetic resonance image (MRI) have largely focused on volumes while less is known about shape asymmetry. We introduce a flexible protocol based on geometric morphometrics to assess patterns of asymmetry in shape and size of mouse brain from microMRI scans. After systematic digitization of landmarks and semilandmarks, we combine multivariate methods for statistical analyses with visualization tools to display the results. No preliminary treatment of the images (e.g. space normalization) is needed to collect data on MRI slices and visual representations improve the interpretation of the results. Results indicated that the protocol is highly repeatable. Asymmetry was more evident for shape than for size. Particularly, fluctuating asymmetry accounted for more variation than directional asymmetry in all brain regions. Since this approach can detect subtle shape variation between sides, it is a promising methodology to explore morphological changes in the brain of model organisms and can be applied in future studies addressing the effect of genetic and environmental factors on brain morphology.

Morphological Integration of the Orbital Region in a Human Ontogenetic Sample

Most studies on craniofacial morphology have focused on adult individuals, but patterns of variation are the outcome of genetic and epigenetic variables that interact throughout ontogeny. Among cranial regions, the orbits exhibit morphological variation and occupy an intermediate position between neurocranial and facial structures. The main objective of this work was to analyze postnatal ontogenetic variation and covariation in the morphology of the orbital region in a cross‐sectional series of humans from 0 to 31 years old. Landmarks and semilandmarks were digitized on the orbital rim, as well as in neighboring neural and facial structures. Data were analyzed using geometric morphometrics. Results indicated that orbital size increases during the first years of postnatal life, while the shape of the orbital aperture does not change significantly with age. In general, the pattern and magnitude of shape covariation do not vary markedly during postnatal life although some subtle shifts were documented. Additionally, the shape of the orbital aperture is more related to the anterior neurocranium than to zygomatic structures, even when the allometry is adjusted. Although we expected some influence from postnatal craniofacial growth and from some functional factors, such as mastication, on the development of the orbits, this assumption was not completely supported by our results. As a whole, our findings are in line with the prediction of an early influence of the eyes and extraocular tissues on orbital morphology, and could be interpreted in relation to processes promoting early neural development that coordinately affects orbital traits and the neurocranial skeleton. Anat Rec, 299:70–80, 2016.

Ontogenetic Patterns of Morphological Variation in the Ectocranial Human Vault

The skull is considered a modular structure in which different parts are influenced by different factors and, as a result, achieve adult shape at different ages. Previous studies have suggested that the basicranium presents a modular pattern that distinguishes sagittal and lateral parts, probably affected by the brain and masticatory structures, respectively. The vault of modern humans, in contrast, has been considered as a highly integrated system mainly influenced by brain growth. Here, we explored developmental shape variation in sagittal and lateral ectocranial vault in humans in order to assess if both regions are ontogenetically dissociated. We used a sample of 135 cranial computed tomography images from 0 to 31 ages. Landmarks and semilandmarks were collected on sagittal and lateral regions and geometric morphometric techniques were applied separately for each region. On the shape coordinates, we used Goodalls F‐test in order to assess the age when the adult configuration is attained. Principal component analysis enabled us to evaluate shape variation during ontogeny. Results indicated that both sagittal and lateral structures attain adult shape at early adolescence. Both regions express coordinated shape modifications probably due to shared developmental factors. It is concluded that masticatory muscles may not exert a strong enough influence to produce independent variation in the lateral traits. Thus, it is likely that the brain integrates sagittal and lateral parts of the vault across human ontogeny. Anat Rec, 296:1008–1015, 2013.

Envejecimiento, pérdida dentaria y cambios craneofaciales/Aging, tooth loss and craneofacial changes

RESUMEN Este trabajo se centra en el analisis de cambios osteoartrosicos observados en esqueletos del cementerio de Rincon Chico 21 (Santa Maria, Catamarca), con el objeto de intentar la reconstruccion de los habitos corporales mas probables y explorar su vinculacion con eventuales divisiones del trabajo en la poblacion que genero este cementerio precolombino. Las manifestaciones osteoartrosicas en los principales sistemas articulares de 56 individuos adultos de ambos sexos fueron registradas, analizadas y comparadas. Los resultados sugieren que en esta comunidad con una economia de subsistencia principalmente basada en la practica de agricultura de regadio y pastoreo de camelidos (Desarrollos Regionales), habria existido una division de tareas y/o actividades potencialmente relacionadas con el sexo de los individuos. Asimismo, los analisis estadisticos aplicados entre los grupos etarios considerados estarian indicando que la edad constituiria un factor determinante en la expresion final de la enfermedad degenerativa articular tanto en las articulaciones de los miembros inferiores como en las del esqueleto axial. ABSTRACT This research is centered on the skeletal analysis of osteoarthritic changes observed in individuals from Rincon Chico 21, a prehistoric burial site at Santa Maria, Catamarca, Argentina. The aim was to try the reconstruction of the most probable corporal behaviours, as well as the possible relationships with labour divisions among individuals from the population that generated the prehistoric cemetery. Osteoarthritic manifestations on the main articular systems of 56 systematically excavated adult skeletons of both sexes were registered, analyzed and compared. Results suggested that in this prehistoric community, with subsistence economy based on agriculture and pastoralism (Regional Developments Period), there may have existed a sexual division of the daily activities. In addition, the results of the statistical analysis applied among the age groups indicate that the age would be an important factor for determining the final expression of the degenerative joint disease, both in the joints of the lower extremities and in the axial skeleton.RESUMEN El estudio de las poblaciones humanas antiguas es complejo y requiere de un enfoque interdisciplinario. La arqueologia argentina esta promoviendo el desarrollo de nuevas lineas de evidencias que incluyen espacios muy activos de interaccion con la biologia. Numerosos estudios biologicos se efectuan sobre los depositos sedimentarios asociados al contexto arqueologico. Los sedimentos asociados a los restos humanos constituyen un recurso de informacion poco explorado y en general, escasamente contemplado en el diseno previo de la excavacion. El presente trabajo aborda el examen de sedimentos de foramenes sacrales de esqueletos humanos pertenecientes al Museo Regional Monsenor Fagnano, Tierra del Fuego, una clase de material arqueologico poco estudiado. La recuperacion de rotiferos, artropodos y parasitos justifica el esfuerzo de muestreo sobre materiales sin asignacion temporal y con escasa referencia espacial. Se puede concluir que el estudio de microfosiles presentes en este tipo de deposito permite maximizar la informacion obtenida del registro bioarqueologico debido a que albergan valiosa informacion paleoambiental, bioantropologica y tafonomica. Asi, el estudio exhaustivo y no destructivo de las muestras arqueologicas resulta un punto crucial en la estrategia de investigacion. ABSTRACT The study of ancient human populations is complex and requires an interdisciplinary approach. The Argentinean archaeology is promoting the development of new research fields, including areas of active interaction with biology. Numerous biological studies are conducted on the sedimentary deposits in association to the archaeological context. The sediments associated to human remains constitute an unexplored source of information. Nevertheless, this material is frequently overlook during excavations and/or insufficient number of samples are taken. The present study analyzes the sediments found in sacral foramina of human skeletons belonging to the Monsenor Fagnano Regional Museum, Tierra del Fuego this is a kind of archaeological material rarely studied. The recovery of rotifers, arthropods and parasites justified the sampling effort on this unusual sediments characterized by a low temporary and spatial reference. It can be concluded that the study of microfossils found in this type of deposit maximized the information obtained from the bioarchaeological registry because it harbors valuable palaeoenvironmental, bioanthropological and taphonomic data. Therefore, the exhaustive and non-destructive study of the archaeological samples is a crucial point in the research strategy