Adaptations to tree-gouging in the anterior masticatory apparatus of marmosets (callithrix) [abstract]

Although all genera of Callitrichinae engage in exudativory to some degree, marmosets (Callithrix, Cebuella) take advantage of exudates to the greatest extent. To facilitate exudate feeding, marmosets use their anterior teeth to gouge holes in bark and actively stimulate gum flow. As such, their anterior mandibular teethpossess specialized adaptations such as thickened labial enamel. Marmosets alsoshow masticatory features that facilitate increased gape, but do not appear to generate relatively large bite forces during gouging. However, even without increased bite force the anterior teeth of gougers likely experience different loading patternscompared to non-gouging platyrrhines. Specifically, one might expect that theanterior teeth and symphysis of marmosets are adapted to accommodate relatively high stresses linked to dissipating forces from yield-resistant and tough tree barks. This study uses histological data from thin- sectioned teeth, microCT data of jaws and teeth, and macroscale tests of simulated symphyseal loads to compare the micro- and macro-architecture of the anterior masticatory apparatus in Callithrix and Saguinus (as well as the outgroup Saimiri). Callithrix differs from the other genera in that its canine enamel possesses a much higher degree of decussation, and its anterior tooth roots are larger relative to alveolar bone volume. However, simulated jaw loading suggests a reduced ability to withstand external forces in the marmoset symphysis. The contrast between increased load-resistance ability in the anterior dentition versus relatively reduced symphyseal strength suggests both a potentially complex loading environment during gouging and a mosaic pattern of dentofacial adaptations to this derived biting behavior

Overview of FEED, the Feeding Experiments End-user Database

The Feeding Experiments End-user Database (FEED) is a research tool developed by the Mammalian Feeding Working Group at the National Evolutionary Synthesis Center that permits synthetic, evolutionary analyses of the physiology of mammalian feeding. The tasks of the Working Group are to compile physiologic data sets into a uniform digital format stored at a central source, develop a standardized terminology for describing and organizing the data, and carry out a set of novel analyses using FEED. FEED contains raw physiologic data linked to extensive metadata. It serves as an archive for a large number of existing data sets and a repository for future data sets. The metadata are stored as text and images that describe experimental protocols, research subjects, and anatomical information. The metadata incorporate controlled vocabularies to allow consistent use of the terms used to describe and organize the physiologic data. The planned analyses address long-standing questions concerning the phylogenetic distribution of phenotypes involving muscle anatomy and feeding physiology among mammals, the presence and nature of motor pattern conservation in the mammalian feeding muscles, and the extent to which suckling constrains the evolution of feeding behavior in adult mammals. We expect FEED to be a growing digital archive that will facilitate new research into understanding the evolution of feeding anatomy

Muscle Logic: New Knowledge Resource for Anatomy Enables Comprehensive Searches of the Literature on the Feeding Muscles of Mammals

Background: In recent years large bibliographic databases have made much of the published literature of biology available for searches. However, the capabilities of the search engines integrated into these databases for text-based bibliographic searches are limited. To enable searches that deliver the results expected by comparative anatomists, an underlying logical structure known as an ontology is required. Development and Testing of the Ontology Here we present the Mammalian Feeding Muscle Ontology (MFMO), a multi-species ontology focused on anatomical structures that participate in feeding and other oral/pharyngeal behaviors. A unique feature of the MFMO is that a simple, computable, definition of each muscle, which includes its attachments and innervation, is true across mammals. This construction mirrors the logical foundation of comparative anatomy and permits searches using language familiar to biologists. Further, it provides a template for muscles that will be useful in extending any anatomy ontology. The MFMO is developed to support the Feeding Experiments End-User Database Project (FEED, https://feedexp.org/), a publicly-available, online repository for physiological data collected from in vivo studies of feeding (e.g., mastication, biting, swallowing) in mammals. Currently the MFMO is integrated into FEED and also into two literature-specific implementations of Textpresso, a text-mining system that facilitates powerful searches of a corpus of scientific publications. We evaluate the MFMO by asking questions that test the ability of the ontology to return appropriate answers (competency questions). We compare the results of queries of the MFMO to results from similar searches in PubMed and Google Scholar. Results and Significance Our tests demonstrate that the MFMO is competent to answer queries formed in the common language of comparative anatomy, but PubMed and Google Scholar are not. Overall, our results show that by incorporating anatomical ontologies into searches, an expanded and anatomically comprehensive set of results can be obtained. The broader scientific and publishing communities should consider taking up the challenge of semantically enabled search capabilities

Structure of a monomeric photosystem II core complex from a cyanobacterium acclimated to far-red light reveals the functions of chlorophylls d and f

Far-red light (FRL) photoacclimation in cyanobacteria provides a selective growth advantage for some terrestrial cyanobacteria by expanding the range of photosynthetically active radiation to include far-red/near-infrared light (700–800 nm). During this photoacclimation process, photosystem II (PSII), the water:plastoquinone photooxidoreductase involved in oxygenic photosynthesis, is modified. The resulting FRL-PSII is comprised of FRL-specific core subunits and binds chlorophyll (Chl) d and Chl f molecules in place of several of the Chl a molecules found when cells are grown in visible light. These new Chls effectively lower the energy canonically thought to define the “red limit” for light required to drive photochemical catalysis of water oxidation. Changes to the architecture of FRL-PSII were previously unknown, and the positions of Chl d and Chl f molecules had only been proposed from indirect evidence. Here, we describe the 2.25 Å resolution cryo-EM structure of a monomeric FRL-PSII core complex from Synechococcus sp. PCC 7335 cells that were acclimated to FRL. We identify one Chl d molecule in the ChlD1 position of the electron transfer chain and four Chl f molecules in the core antenna. We also make observations that enhance our understanding of PSII biogenesis, especially on the acceptor side of the complex where a bicarbonate molecule is replaced by a glutamate side chain in the absence of the assembly factor Psb28. In conclusion, these results provide a structural basis for the lower energy limit required to drive water oxidation, which is the gateway for most solar energy utilization on earth

A quantitative assessment of the supraorbital region in modern Melanesian crania

Includes bibliographical references (pages [201]-214)The supraorbital region in modem Homo sapiens has been a topic of continued debate concerning its relationship within the larger craniofacial context and regarding a functional and/or structural explanation of supraorbital expression. A morphometric examination of the supraorbital region in a sample of eighty modem Melanesian crania was conducted to examine these two areas of ongoing discussion. A battery of quantitative dimensions, including measurements taken from CT scanning, were taken on the cranial sample and analyzed using both bivariate and multivariate statistical procedures. The results indicated that the supraorbital region in modem Melanesian crania is intricately related to other metric craniofacial dimensions. The supraorbital region is not realistically considered outside of the craniofacial context. The most pervasive influence upon supraorbital development is craniofacial size. Other interrelationships (between specific supraorbital dimensions) and relationships (with other craniofacial variables) exhibit smaller levels of explained variation. The lateral supraorbital heights are differentiated from both medial supraorbital height and supraorbital projections. The lateral heights are linked to upper facial and frontal breadths and contrasted to frontal length and lower facial breadth dimensions. Conversely, supraorbital projections are associated with frontal lengths and contrasted with frontal and upper facial breadths. Medial supraorbital height is hypothesized to be directly related to the development of the frontal sinus. A second focus of this project was the testing of several hypotheses taken from the functional and/or structural models used to account for the supraorbital region. Among the biomechanical models, only the hypothesis derived from the neuro-facial torsion model was supported throughout the supraorbital region. The lateral supraorbital region was linked to temporalis muscle size following the prediction of the bent beam model. However, no other hypotheses derived from this model were supported. Support for the hypotheses derived from the spatial model was found throughout the hypothesis testing. No support for the influence of prognathism upon supraorbital development was offered. A relationship was exhibited between longer crania and larger supraorbitals. The observation that several hypotheses received support in this section highlights the probability that the supraorbital region is influenced by multiple non-mutually exclusive factors.M.A. (Master of Arts