Differential iron requirements for osteoblast and adipocyte differentiation

Bone marrow mesenchymal progenitor cells are precursors for various cell types including osteoblasts, adipocytes, and chondrocytes. The external environment and signals act to direct the pathway of differentiation. Importantly, situations such as aging and chronic kidney disease display alterations in the balance of osteoblast and adipocyte differentiation, adversely affecting bone integrity. Iron deficiency, which can often occur during aging and chronic kidney disease, is associated with reduced bone density. The purpose of this study was to assess the effects of iron deficiency on the capacity of progenitor cell differentiation pathways. Mouse and human progenitor cells, differentiated under standard osteoblast and adipocyte protocols in the presence of the iron chelator deferoxamine (DFO), were used. Under osteogenic conditions, 5μM DFO significantly impaired expression of critical osteoblast genes, including osteocalcin, type 1 collagen, and dentin matrix protein 1. This led to a reduction in alkaline phosphatase activity and impaired mineralization. Despite prolonged exposure to chronic iron deficiency, cells retained viability as well as normal hypoxic responses with significant increases in transferrin receptor and protein accumulation of hypoxia inducible factor 1α. Similar concentrations of DFO were used when cells were maintained in adipogenic conditions. In contrast to osteoblast differentiation, DFO modestly suppressed adipocyte gene expression of peroxisome-proliferating activated receptor gamma, lipoprotein lipase, and adiponectin at earlier time points with normalization at later stages. Lipid accumulation was also similar in all conditions. These data suggest the critical importance of iron in osteoblast differentiation, and as long as the external stimuli are present, iron deficiency does not impede adipogenesis. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.Daniel F. Edwards III, Christopher J. Miller, Arelis Quintana-Martinez, Christian S. Wright, Matthew Prideaux, Gerald J. Atkins, William R. Thompson, and Erica L. Clinkenbear

Understanding morphological variation in the extant koala as a framework for identification of species boundaries in extinct koalas (Phascolarctidae; Marsupialia)

We document morphological variation (both geographical and sexual) in the dentition of the extant koala, Phascolarctos cinereus, in order to facilitate discrimination of species boundaries in extinct phascolarctids. Considerable variation is evident in dental structures previously used to diagnose several phascolarctid fossil species. Consistent patterns of morphological variation are not evident between sexes or geographic regions, with variation as great between samples as within them. Metric variation is evident between the sexes in upper molar dimensions with Victorian (southern) males significantly larger than Victorian females, although this is not reflected in lower molar dimensions or in the Queensland (northern) sample. Male koalas from southern populations generally display significantly larger molars than their northern counterparts; however this trend is not evident in female upper molar dimensions. In both males and females, some, but not all, lower molar dimensions are larger in southern populations than northern. In light of these results, a systematic revision of species of Litokoala suggests L. dicktedfordi' is a junior synonym of L. kutjamarpensis, and the poorly known L. thurmerae is regarded to be a nomen dubium. Further, we describe a partial cranium of a new species of koala from Early Miocene sediments in the Riversleigh World Heritage Area, northern Australia. Litokoala dicksmithi sp. nov. is the fifth koala species recorded from the diverse rainforest assemblages of Riversleigh and the third species referred to the Oligo-Miocene genus Litokoala. Aspects of cranial morphology, including a shortened robust rostrum and broad, irregular nasal aperture, confirm placement of Litokoala as sister taxon to the modern genus Phascolarctos. Relatively large orbits and small body size suggest the possibility that L. dicksmithi was nocturnal, had enhanced visual acuity, and was a more agile arboreal species than the relatively sedentary extant koala

Teaching of Energy Issues: A debate proposal for a GLobal Reorientation

The growing awareness of serious difficulties in the learning of energy issues has produced a great deal of research, most of which is focused on specific conceptual aspects. In our opinion, the difficulties pointed out in the literature are interrelated and connected to other aspects (conceptual as well as procedural and axiological), which are not sufficiently taken into account in previous research. This paper aims to carry out a global analysis in order to avoid the more limited approaches that deal only with individual aspects. From this global analysis we have outlined 24 propositions that are put forward for debate to lay the foundations for a profound reorientation of the teaching of energy topics in upper high school courses, in order to facilitate a better scientific understanding of these topics, avoid many students' misconceptions and enhance awareness of the current situation of planetary emergency

Bohra nullarbora sp. nov., a second tree-kangaroo (Marsupialia: Macropodidae) from the Pleistocene of the Nullarbor Plain, Western Australia

Bohra nullarbora sp. nov. is described from a partial skeleton collected from a diverse Pleistocene vertebrate assemblage preserved in Leaena’s Breath Cave, Nullarbor Plain, Western Australia. It is distinguished from its Nullarbor contemporary, B. illuminata, by having different cranial proportions, smaller cheek teeth and a relatively narrower upper premolar. It also differs in a number of postcranial attributes, which may reflect slight variation in locomotory capabilities. The unexpected discovery that, in the relatively recent geological past, two large arboreal kangaroos inhabited the now ‘Treeless’ Plain effectively highlights how little we still know about the Pleistocene history of Western Australia, and of the drier regions of the continent in general

Functional morphology of the forelimb of living and extinct tree-kangaroos (Marsupialia: Macropodidae)

Tree-kangaroos are a unique group of arboreal marsupials that evolved from terrestrial ancestors. The recent discovery of well-preserved specimens of extinct tree-kangaroo species (genus Bohra) within Pleistocene cave deposits of south-central Australia provides a unique opportunity to examine adaptive evolution of tree-kangaroos. Here, we provide the first detailed description of the functional anatomy of the forelimb, a central component of the locomotor complex, in the extant Dendrolagus lumholtzi, and compare its structure and function with representatives of other extant marsupial families. Several features were interpreted as adaptations for coping with a discontinuous, uneven and three-dimensional arboreal substrate through enhanced muscular strength and dexterity for propulsion, grasping, and gripping with the forelimbs. The forelimb musculoskeletal anatomy of Dendrolagus differed from terrestrial kangaroos in the following principal ways: a stronger emphasis on the development of muscles groups responsible for adduction, grasping, and gripping; the enlargement of muscles that retract the humerus; and modified shape of the scapula and bony articulations of the forelimb bones to allow improved mobility. Many of these attributes are convergent with other arboreal marsupials. Tree-kangaroos, however, still retain the characteristic bauplan of their terrestrial ancestors, particularly with regard to skeletal morphology, and the muscular anatomy of the forelimb highlights a basic conservatism within the group. In many instances, the skeletal remains of Bohra have similar features to Dendrolagus that suggest adaptations to an arboreal habit. Despite the irony of their retrieval from deposits of the Nullarbor “Treeless” Plain, forelimb morphology clearly shows that the species of Bohra were well adapted to an arboreal habitat

The skeleton of Congruus kitcheneri, a semiarboreal kangaroo from the Pleistocene of southern Australia

The macropodine kangaroo, Wallabia kitcheneri, was first described in 1989 from a Pleistocene deposit within Mammoth Cave, southwestern Australia, on the basis of a few partial dentaries and maxilla fragments. Here, we recognize W. kitcheneri within the Pleistocene assemblages of the Thylacoleo Caves, south-central Australia, where it is represented by several cranial specimens and two near-complete skeletons, a probable male and female. We reallocate this species to the hitherto monotypic genus Congruus. Congruus kitcheneri differs from all other macropodid species by having a highly unusual pocket within the wall of the nasal cavity. It is distinguished from C. congruus by having a longer, narrower rostrum, a taller occiput and a deeper jugal. Congruus is closest to Protemnodon in overall cranial morphology but is smaller and less robust. In most postcranial attributes, Congruus also resembles Protemnodon, including general limb robustness and the atypical ratio of 14 thoracic to five lumbar vertebrae. It is distinguished by the high mobility of its glenohumeral joints, the development of muscle attachment sites for strong adduction and mobility of the forelimb, and large, robust manual and pedal digits with strongly recurved distal phalanges. These adaptations resemble those of tree-kangaroos more than ground-dwelling macropodines. We interpret this to imply that C. kitcheneri was semiarboreal, with a propensity to climb and move slowly through trees. This is the first evidence for the secondary adoption of a climbing habit within crown macropodines

A new Pleistocene tree-kangaroo (Diprotodontia: Macropodidae) from the Nullarbor Plain of south-central Australia

This paper describes a new tree-kangaroo of the extinct genus Bohra (B. illuminata sp. nov.). Its remains were collected from a diverse middle Pleistocene fauna preserved in caves recently discovered beneath the Nullarbor Plain of south-central Australia. The adult holotype and juvenile paratype are represented by associated cranial and postcranial material. They confirm that two previously known species, B. paulae and B. wilkinsonorum, which were described on the basis of disparate parts of the skeleton, are congeneric. While Bohra is closest in morphology to the extant tree-kangaroo genus Dendrolagus, it shares several similarities with Petrogale (rock-wallabies). This is consistent with recent molecular studies that suggest that tree-kangaroos and rock-wallabies share a common ancestry

The anterior nasal region in the Red Kangaroo (Macropus rufus) suggests adaptation for thermoregulation and water conservation

The Red Kangaroo, Macropus rufus, is a specialist inhabitant of the hot, arid interior of Australia. Physiological adaptations that enable it to survive in this extreme environment are not fully understood, but include modifications of the kidney to optimize water economy and the ability to reabsorb water from digesta. To date, no nasal adaptations have been revealed in M. rufus, even though specializations in this region for thermoregulation and water conservation are common in arid-zone placental mammals, such as camels. Here, we investigate the nasal osteology and histology of M. rufus and describe two previously unreported features. Computed-tomographic scans reveal two modifications of the premaxillae in adult M. rufus: a sulcus on the inner margin of lateral walls of the nasal cavity, and a longitudinal recess lying in the floor of the nasal cavity. Histological analysis shows that these are lined with simple respiratory epithelia; no additional glandular structures were evident. The submucosa of the lateral sulcus was highly vascular, suggesting a role in thermoregulation. The lamina propria of the ventral recess was relatively avascular, but contains lymphatic vessels. Presence of the lateral sulcus in the tropical Antilopine Kangaroo, M. antilopinus, and absence of either feature in the more mesic-adapted grey kangaroos (M. fuliginosus, M. giganteus), lends support to the hypothesis that this premaxillary modification may reflect adaptation of the nasal cavity for thermoregulation. The ventral nasal recess was unique to M. rufus and we suggest that it may play a role in water conservation in this species via reclamation of moisture by the lymphatic system. To our knowledge, this is the first evidence of a nasal mechanism for water reclamation in mammals

Scrapheap Challenge: A novel bulk-bone metabarcoding method to investigate ancient DNA in faunal assemblages

Highly fragmented and morphologically indistinct fossil bone is common in archaeological and paleontological deposits but unfortunately it is of little use in compiling faunal assemblages. The development of a cost-effective methodology to taxonomically identify bulk bone is therefore a key challenge. Here, an ancient DNA methodology using high-throughput sequencing is developed to survey and analyse thousands of archaeological bones from southwest Australia. Fossils were collectively ground together depending on which of fifteen stratigraphical layers they were excavated from. By generating fifteen synthetic blends of bulk bone powder, each corresponding to a chronologically distinct layer, samples could be collectively analysed in an efficient manner. A diverse range of taxa, including endemic, extirpated and hitherto unrecorded taxa, dating back to c.46,000 years BP was characterized. The method is a novel, cost-effective use for unidentifiable bone fragments and a powerful molecular tool for surveying fossils that otherwise end up on the taxonomic “scrapheap”

Revisiting the late Quaternary fossiliferous infills of Cathedral Cave, Wellington Caves (central eastern New South Wales, Australia)

OnlinePublThe Wellington Caves were the first Australian locality from which Europeans collected and analysed vertebrate fossils. Within this system, Cathedral Cave contains Australia's stratigraphically deepest sequence of fossil‐ bearing infill sediments, the age and depositional history of which has been poorly understood. Here we present results from a new excavation of the upper 4.2 m of the deposit, reanalysing the stratigraphy, petrography, sedimentology and geochemistry, and employing optically stimulated luminescence dating, radiocarbon dating and Bayesian age modelling to establish a robust chronology. We recognise 13 sedimentary layers and sublayers in two stratigraphic units. Unit 2 accumulated between 72 000 ± 5000 and 38 000 ± 7000 years ago as sediments and animals entered through a now‐blocked ceiling hole. Accumulation halted for around 30 000 years when the hole closed. Unit 1 accumulated when deposition was reinitiated around 7000 ± 2000 years ago, continuing through to a few hundred years ago. Our chronology refutes earlier dating of the deposit, which suggested that extinct Pleistocene megafauna taxa persisted locally until the Last Glacial Maximum. It confirms the deposit as one of the few in Australia that formed during the interval of major environmental upheaval marked by the arrival of humans, variable climate and the extinction of many megafaunal species.Diana A. Fusco, Lee J. Arnold, Grant A. Gully, Vladimir A. Levchenko, Geraldine E. Jacobsen, And Gavin J. Prideau