Mineral deposition in the tympanic bullae of newborn Cetacea, Ruminantia and Hippopotamids represented in a simplified cladistic tree.

<p>Evolution of Cetacea and Arctiodactyla reflects progressive skeletal adaptation to aquatic/terrestrial life. We hypothesize that fetal and early post-natal mineral matter deposition in the tympanic bulla represents a key adaptive tract for immediate survival in the aquatic environment. Values of BMD, expressed as g/cm² are rounded to the next decimal value.</p

Epithelium of the dolphin trachea;Innervation of the dolphin trachea from Vascularization of the trachea in the bottlenose dolphin: comparison with bovine and evidence for evolutionary adaptations to diving

Cilia are evident in the pseudostratified epithelium of the trachea of the bottlenose dolphin. Blood vessels are present in the lamina propria, superficial to the deeper layer where the vascular lacunae are located. Scale bar = 100μm;Several (viscero-motor) nerve bundles (asterisk) travel in the connective tissue interspersed among the vascular lacunae of the trachea of the bottlenose dolphin. Scale bar = 100μ

Representation of progressive growth of the tympanic bullae (black bars) and skeleton (orange bars) in bovine and fin whales.

<p>The deposition of bone mineral matter starts in the early fetal stages in fin whales, increases steadily in the newborn and achieves comparatively high density in the adult. Bone density in the bovine bulla appears negligible in the early developmental stages and most of the bone mineral content is added in postnatal life.</p

Epithelium of the dolphin trachea;Innervation of the dolphin trachea from Vascularization of the trachea in the bottlenose dolphin: comparison with bovine and evidence for evolutionary adaptations to diving

Cilia are evident in the pseudostratified epithelium of the trachea of the bottlenose dolphin. Blood vessels are present in the lamina propria, superficial to the deeper layer where the vascular lacunae are located. Scale bar = 100μm;Several (viscero-motor) nerve bundles (asterisk) travel in the connective tissue interspersed among the vascular lacunae of the trachea of the bottlenose dolphin. Scale bar = 100μ

Epithelium of the dolphin trachea;Innervation of the dolphin trachea from Vascularization of the trachea in the bottlenose dolphin: comparison with bovine and evidence for evolutionary adaptations to diving

Cilia are evident in the pseudostratified epithelium of the trachea of the bottlenose dolphin. Blood vessels are present in the lamina propria, superficial to the deeper layer where the vascular lacunae are located. Scale bar = 100μm;Several (viscero-motor) nerve bundles (asterisk) travel in the connective tissue interspersed among the vascular lacunae of the trachea of the bottlenose dolphin. Scale bar = 100μ

DXA scan reports of the left tympanic bullae of fin whales of different ages.

<p>a, 6 months fetus (MSNM Ma7486); b, newborn (MSNM Ma4881); c, adult (MSNM Ma4582), showing the bone mineral content (BMC) and the BMD of the tympanic bulla (R1); periotic bones (R2); whole specimen (GLOBAL).</p

BMD values of tympanic bullae (g/cm²).

<p>All measures refer to the left tympanic bullae. Left-to-right differences in shape, size and density were negligible in our experimental series.</p><p>MMMTB = Mediterranean marine mammal tissue bank, University of Padova; Legnaro (PD), Italy; MSNM Ma = Museum of Natural History of Milan; Milan (Italy); MSNGe = Museum of Natural History “G. Doria” of Genova; Genova (Italy); UniPD = Collection of the Faculty of Veterinary Medicine of the University of Padova; Legnaro (PD), Italy.</p>*<p> = isolated bulla from specimen stranded in extra-national waters, body destroyed; private collector, Milan (Italy).</p

Distribution of CSBPSs in a single tRNA.

<p>CSBPS, change in sequence in a base pair of a stem; FCBC, fully compensatory base change; HCBC, hemi compensatory base change; Mismatch, mismatch in a base pair of a stem; SPIC, stem position involved in base change. The number/percentage of SPICs is provided in cyan. A green background is used to mark the number of FCBCs occurring in a tRNA as well as the percentage that they represent with respect to the total number of FCBCs. The orange and red backgrounds are used for the number/percentage of HCBCs and Mismatches. A purple background is used for number/percentage of CSBPSs.</p

Mapping of CSBPSs in the Cetacea phylogenetic tree.

<p>CSBPS, change in sequence in a base pair of a stem; FCBC, fully compensatory base change; HCBC, hemi compensatory base change; Mismatch, mismatch in a base pair of a stem; Number of FCBCs, HCBCs, and Mismatches (included their sum CSBPSs) occurring at the nodes of the reference phylogenetic tree. The asterisk associated with some CSBPS values indicates that these CSBPSs were subjected to successive changes in one/some of the taxa downstream of the considered node. For details on the type of FCBCs, HCBCs, and mismatches occurring at a single node, please refer to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158129#pone.0158129.s008" target="_blank">S7</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158129#pone.0158129.s010" target="_blank">S9</a> Figs.</p

The tRNA nomenclature and the gene order of vertebrate mtDNA.

<p>Ac, pair of the acceptor stem; dh, pair of the DHU stem; an, pair of the anticodon stem; tp, pair of the TΨC stem. The numbering of pairs follows a 5’ → 3’ orientation. The 5’ nucleotide of a pair is marked with a, while the 3’ base is marked with b. The numbering scheme of Sprinzl et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0158129#pone.0158129.ref020" target="_blank">20</a>] is provided only for the stems. Base pairings are indicated as follows: –, canonical Watson-Crick base pairing; •, base pairing involving G and T; |, base pairing implying a mismatch. A The gene order of vertebrate mtDNA is depicted at the bottom, linearised starting from <i>cox1</i>. Genes encoded on the α-strand (right to left orientation) are underlined in green, while those encoded on the β-strand are underlined in red (left to right orientation). Gene nomenclature: <i>atp6</i> and <i>atp8</i>: ATP synthase subunits 6 and 8; <i>cob</i>: apocytochrome b; <i>cox1</i>-<i>3</i>: cytochrome c oxidase subunits 1–3; <i>nad1-6</i> and <i>nad4L</i>: NADH dehydrogenase subunits 1–6 and 4L; <i>rrnS</i> and <i>rrnL</i>: small and large subunit ribosomal RNA (rRNA) genes; and X: transfer RNA (tRNA) genes, where X is the one-letter abbreviation of the corresponding amino acid. In particular, L1 identifies the CTN codon family; L2 the TTR codon family, S1 the AGY codon family, and S2 the TCN codon family. CR, Control Region.</p