An ape partial postcranial skeleton (KNM-NP 64631) from the Middle Miocene of Napudet, northern Kenya.

An ape partial postcranial skeleton (KNM-NP 64631) was recovered during the 2015-2021 field seasons at Napudet, a Middle Miocene (∼13 Ma) locality in northern Kenya. Bony elements representing the shoulder, elbow, hip, and ankle joints, thoracic and lumbar vertebral column, and hands and feet, offer valuable new information about the body plan and positional behaviors of Middle Miocene apes. Body mass estimates from femoral head dimensions suggest that the KNM-NP 64631 individual was smaller-bodied (c. 13-17 kg) than some Miocene taxa from eastern Africa, including Ekembo nyanzae, and probably Equatorius africanus or Kenyapithecus wickeri, and was more comparable to smaller-bodied male Nacholapithecus kerioi individuals. Similar to many Miocene apes, the KNM-NP 64631 individual had hip and hallucal tarsometatarsal joints reflecting habitual hindlimb loading in a variety of postures, a distal tibia with a large medial malleolus, an inflated humeral capitulum, probably a long lumbar spine, and a long pollical proximal phalanx relative to femoral head dimensions. The KNM-NP 64631 individual departs from most Early Miocene apes in its possession of a more steeply beveled radial head and deeper humeral zona conoidea, reflecting enhanced supinating-pronating abilities at the humeroradial joint. The KNM-NP 64631 individual also differs from Early Miocene Ekembo heseloni in having a larger elbow joint (inferred from radial head size) relative to the mediolateral width of the lumbar vertebral bodies and a more asymmetrical talar trochlea, and in these ways recalls inferred joint proportions for, and talocrural morphology of, N. kerioi. Compared to most Early Miocene apes, the KNM-NP 64631 individual likely relied on more forelimb-dominated arboreal behaviors, perhaps including vertical climbing (e.g., extended elbow, hoisting). Moreover, the Napudet ape partial postcranial skeleton suggests that an arboreally adapted body plan characterized by relatively large (here, based on joint size) forelimbs, but lacking orthograde suspensory adaptations, may not have been 'unusual' among Middle Miocene apes.

Transcriptomic landscape of human induced pluripotent stem cell-derived osteogenic differentiation identifies a regulatory role of KLF16.

Osteogenic differentiation is essential for bone development and metabolism, but the underlying gene regulatory networks have not been well investigated. We differentiated mesenchymal stem cells, derived from 20 human induced pluripotent stem cell lines, into preosteoblasts and osteoblasts, and performed systematic RNA-seq analyses of 60 samples for differential gene expression. We noted a highly significant correlation in expression patterns and genomic proximity among transcription factor (TF) and long noncoding RNA (lncRNA) genes. We identified TF-TF regulatory networks, regulatory roles of lncRNAs on their neighboring coding genes for TFs and splicing factors, and differential splicing of TF, lncRNA, and splicing factor genes. TF-TF regulatory and gene co-expression network analyses suggested an inhibitory role of TF KLF16 in osteogenic differentiation. We demonstrate that in vitro overexpression of human KLF16 inhibits osteogenic differentiation and mineralization, and in vivo Klf16+/- mice exhibit increased bone mineral density, trabecular number, and cortical bone area. Thus, our model system highlights the regulatory complexity of osteogenic differentiation and identifies novel osteogenic genes.

A thyroidea ima artery variation providing collateral circulation to the mediastinum.

The thyroidea ima artery (TIA) is a highly variable arterial deviation of the blood supply to the thyroid gland with critical implications for surgical neck procedures such as tracheostomy. Though relatively common in the population at large (~ 4%), most TIA variations are related to the origin of the artery and whether it emerges from the common sites of the brachiocephalic trunk, aortic arch, and right common carotid artery, or another more unique vessel-as opposed to its dispersion pattern. TIA variants generally supply the thyroid gland, occasionally co-occurring with absent thyroid arteries. Here, we report on a unique case of a four-pronged variation of the TIA discovered during an anatomy laboratory dissection of first-year medical students. This variant originated from the brachiocephalic trunk and had three branches terminating in the thyroid gland and a fourth branch traveling into the thorax to provide accessory circulation in the mediastinum. Specifically, small arterial branches from the inferior TIA branch supplied the anterior pericardium and surrounding adipose tissue, in addition to normal pericardiacophrenic circulation. We discuss the potential embryological and clinical relevance of this unique variation and voice further support for imaging as a requirement before surgical neck procedures to prevent catastrophic bleeding in the event of a TIA variant.

In utero exposure to selective serotonin re-uptake inhibitor affects murine mandibular development.

OBJECTIVES: Antidepressants, specifically Selective Serotonin Re-uptake Inhibitors (SSRIs), that alter serotonin metabolism are currently the most commonly prescribed drugs for the treatment of depression. There is some evidence to suggest these drugs contribute to birth defects. As jaw development is often altered in craniofacial birth defects, the purpose of this study was to interrogate the effects of in utero SSRI exposure in a preclinical model of mandible development. MATERIALS AND METHODS: Wild-type C57BL6 mice were used to produce litters that were exposed in utero to an SSRI, Citalopram (500 µg/day). Murine mandibles from P15 pups were analysed for a change in shape and composition. RESULTS: Analysis indicated an overall shape change with total mandibular length and ramus height being shorter in exposed pups as compared to controls. Histomorphometric analysis revealed that first molar length was longer in exposed pups while third molar length was shorter in exposed as compared to control. Histological investigation of molars and surrounding periodontium revealed no change in collagen content of the molar in exposed pups, some alteration in collagen composition in the periodontium, increased alkaline phosphatase in molars and periodontium and decreased mesenchymal cell marker presence in exposed mandibles. CONCLUSION: The results of this study reveal SSRI exposure may interrupt mandible growth as well as overall dental maturation in a model of development giving insight into the expectation that children exposed to SSRIs may require orthodontic intervention.

New hominin remains and revised context from the earliest Homo erectus locality in East Turkana, Kenya.

The KNM-ER 2598 occipital is among the oldest fossils attributed to Homo erectus but questions have been raised about whether it may derive from a younger horizon. Here we report on efforts to relocate the KNM-ER 2598 locality and investigate its paleontological and geological context. Although located in a different East Turkana collection area (Area 13) than initially reported, the locality is stratigraphically positioned below the KBS Tuff and the outcrops show no evidence of deflation of a younger unit, supporting an age of >1.855 Ma. Newly recovered faunal material consists primarily of C4 grazers, further confirmed by enamel isotope data. A hominin proximal 3rd metatarsal and partial ilium were discovered <50 m from the reconstructed location where KNM-ER 2598 was originally found but these cannot be associated directly with the occipital. The postcrania are consistent with fossil Homo and may represent the earliest postcrania attributable to Homo erectus.

Evidence of fatal skeletal injuries on Malapa Hominins 1 and 2.

Malapa is one of the richest early hominin sites in Africa and the discovery site of the hominin species, Australopithecus sediba. The holotype and paratype (Malapa Hominin 1 and 2, or MH1 and MH2, respectively) skeletons are among the most complete in the early hominin record. Dating to approximately two million years BP, MH1 and MH2 are hypothesized to have fallen into a natural pit trap. All fractures evident on MH1 and MH2 skeletons were evaluated and separated based on wet and dry bone fracture morphology/characteristics. Most observed fractures are post-depositional, but those in the right upper limb of the adult hominin strongly indicate active resistance to an impact, while those in the juvenile hominin mandible are consistent with a blow to the face. The presence of skeletal trauma independently supports the falling hypothesis and supplies the first evidence for the manner of death of an australopith in the fossil record that is not attributed to predation or natural death.

The effect of the Achilles tendon on trabecular structure in the primate calcaneus.

Humans possess the longest Achilles tendon relative to total muscle length of any primate, an anatomy that is beneficial for bipedal locomotion. Reconstructing the evolutionary history of the Achilles tendon has been challenging, in part because soft tissue does not fossilize. The only skeletal evidence for Achilles tendon anatomy in extinct taxa is the insertion site on the calcaneal tuber, which is rarely preserved in the fossil record and, when present, is equivocal for reconstructing tendon morphology. In this study, we used high-resolution three-dimensional microcomputed tomography (micro-CT) to quantify the microstructure of the trabecular bone underlying the Achilles tendon insertion site in baboons, gibbons, chimpanzees, and humans to test the hypothesis that trabecular orientation differs among primates with different tendon morphologies. Surprisingly, despite their very different Achilles tendon lengths, we were unable to find differences between the trabecular properties of chimpanzee and human calcanei in this specific region. There were regional differences within the calcaneus in the degree of anisotropy (DA) in both chimpanzees and humans, though the patterns were similar between the two species (higher DA inferiorly in the calcaneal tuber). Our results suggest that while trabecular bone within the calcaneus varies, it does not respond to the variation of Achilles tendon morphology across taxa in the way we hypothesized. These results imply that internal bone architecture may not be informative for reconstructing Achilles tendon anatomy in early hominins.

Cochlin immunostaining of inner ear pathologic deposits and proteomic analysis in DFNA9 deafness and vestibular dysfunction.

Seven missense mutations and one in-frame deletion mutation have been reported in the coagulation factor C homology (COCH) gene, causing the adult-onset, progressive sensorineural hearing loss and vestibular disorder at the DFNA9 locus. Prevalence of COCH mutations worldwide is unknown, as there is no systematic screening effort for late-onset hearing disorders; however, to date, COCH mutations have been found on four continents and the possibility of COCH playing an important role in presbycusis and disorders of imbalance has been considered. Cochlin (encoded by COCH) has also been shown as a major target antigen for autoimmune sensorineural hearing loss. In this report, we present histopathology, immunohistochemistry and proteomic analyses of inner ear tissues from post-mortem DFNA9 temporal bone samples of an individual from a large Dutch kindred segregating the P51S mutation and adult human unaffected controls, and wild-type (+/+) and Coch null (-/-) knock-out mice. DFNA9 is an inner ear disorder with a unique histopathology showing loss of cellularity and aggregation of abundant homogeneous acellular eosinophilic deposits in the cochlear and vestibular labyrinths, similar to protein aggregation in well-known neurodegenerative disorders. By immunohistochemistry on the DFNA9 temporal bone sections, we have shown cochlin staining of the characteristic cochlear and vestibular deposits, indicating aggregation of cochlin in the same structures in which it is normally expressed. Proteomic analysis identified cochlin as the most abundant protein in mouse and human cochleae. The high-level expression and stability of cochlin in the inner ear, even in the absence and severe atrophy of the fibrocytes that normally express COCH, are shown through these studies and further elucidate the pathobiologic events occurring in DFNA9 leading to hearing loss and vestibular dysfunction.

A novel DFNA9 mutation in the vWFA2 domain of COCH alters a conserved cysteine residue and intrachain disulfide bond formation resulting in progressive hearing loss and site-specific vestibular and central oculomotor dysfunction.

Mutations within the COCH gene (encoding the cochlin protein) lead to auditory and vestibular impairment in the DFNA9 disorder. In this study, we describe the genetic mapping of progressive autosomal dominant sensorineural hearing loss first affecting high-frequency auditory thresholds within a human pedigree to the long arm of chromosome 14 in band q12. A maximal pairwise LOD score of 7.08 was obtained with marker D14S1021. We identified a c.1625G > T mutation in exon 12 of COCH that co-segregates with auditory dysfunction in the pedigree. The mutation results in a predicted p.C542F substitution at an evolutionarily conserved cysteine residue in the C-terminus of cochlin. The c.1625G > T transversion in COCH exon 12 represents the first reported mutation outside of the LCCL domain which is encoded by exons 4 and 5. The 542F mutant cochlin is translated and secreted by transfected mammalian cells. Western blot analysis under non-reducing and reducing conditions suggests that the 542F mutation alters intramolecular cochlin disulfide bond formation. In the vestibular system, a progressive horizontal canal hypofunction and a probable saccular otolith challenge were detected in family members with the c.1625G > T COCH alteration. Abnormal central oculomotor test results in family members with the c.1625G > T COCH alteration imply a possible central nervous system change not previously noted in DFNA9 pedigrees harboring mutations within the LCCL domain.

Isolation from cochlea of a novel human intronless gene with predominant fetal expression.

We have cloned a novel human gene, designated PFET1 (predominantly fetal expressed T1 domain) (HUGO-approved symbol KCTD12 or C13orf2), by subtractive hybridization and differential screening of human fetal cochlear cDNA clones. Also, we have identified the mouse homolog, designated Pfet1. PFET1/Pfet1 encode a single transcript of approximately 6 kb in human, and three transcripts of approximately 4, 4.5, and 6 kb in mouse with a 70% GC-rich open reading frame (ORF) consisting of 978 bp in human and 984 bp in mouse. Both genes have unusually long 3' untranslated (3' UTR) regions (4996 bp in human PFET1, 3700 bp in mouse Pfet1) containing 12 and 5 putative polyadenylation consensus sequences, respectively. Pfetin, the protein encoded by PFET1/Pfet1, is predicted to have 325 amino acids in human and 327 amino acids in mouse and to contain a voltage-gated potassium (K+) channel tetramerization (T1) domain. Otherwise, to date these genes have no significant homology to any known gene. PFET1 maps to the long arm of human chromosome 13, in band q21 as shown by FISH analysis and STS mapping. Pfet1 maps to mouse chromosome 14 near the markers D14Mit8, D14Mit93, and D14Mit145.1. The human 6 kb transcript is present in a variety of fetal organs, with highest expression levels in the cochlea and brain and, in stark contrast, is detected only at extremely low levels in adult organs, such as brain and lung. Immunohistochemistry with a polyclonal antibody raised against a synthetic peptide to PFET1 sequence (pfetin) reveals immunostaining in a variety of cell types in human, monkey, mouse, and guinea pig cochleas and the vestibular system, including type I vestibular hair cells.