Organismal evolution of the 3D genome: The conformation of chromosomes within the nucleus can reflect a cell's type or state. However, studies of the conservation and evolutionary history of the mechanisms regulating genome structure across species are lacking. Hoencamp et al. mapped three-dimensional (3D) genome organization in 24 eukaryote species, including animals, fungi, and plants. At interphase, species' telomeres and centromeres either clustered across chromosomes or oriented in a polarized state maintaining individual chromosomal territories within the cell, a difference attributed to condensin II. An experimental loss of condensin II in human cells promotes the formation of centromere clusters but has no effect on loop or compartment formation. Whether the structure of the 3D genome varies across species may thus depend on whether they carry a functional condensin II gene. Science , abe2218, this issue p. 984

The emergence of viruses such as severe acute respiratory syndrome coronavirus and Nipah virus has underscored the role of animal reservoirs in human disease and the need for reservoir surveillance. Here, we used a panviral DNA microarray to investigate the death of a captive beluga whale in an aquatic park. A highly divergent coronavirus, tentatively named coronavirus SW1, was identified in liver tissue from the deceased whale. Subsequently, the entire genome of SW1 was sequenced, yielding a genome of 31,686 nucleotides. Phylogenetic analysis revealed SW1 to be a novel virus distantly related to but most similar to group III coronaviruses.

From September to December 2011, 162 New England harbor seals died in an outbreak of pneumonia. Sequence analysis of postmortem samples revealed the presence of an avian H3N8 influenza A virus, similar to a virus circulating in North American waterfowl since at least 2002 but with mutations that indicate recent adaption to mammalian hosts. These include a D701N mutation in the viral PB2 protein, previously reported in highly pathogenic H5N1 avian influenza viruses infecting people. Lectin staining and agglutination assays indicated the presence of the avian-preferred SAα-2,3 and mammalian SAα-2,6 receptors in seal respiratory tract, and the ability of the virus to agglutinate erythrocytes bearing either the SAα-2,3 or the SAα-2,6 receptor. The emergence of this A/harbor seal/Massachusetts/1/2011 virus may herald the appearance of an H3N8 influenza clade with potential for persistence and cross-species transmission. IMPORTANCE The emergence of new strains of influenza virus is always of great public concern, especially when the infection of a new mammalian host has the potential to result in a widespread outbreak of disease. Here we report the emergence of an avian influenza virus (H3N8) in New England harbor seals which caused an outbreak of pneumonia and contributed to a U.S. federally recognized unusual mortality event (UME). This outbreak is particularly significant, not only because of the disease it caused in seals but also because the virus has naturally acquired mutations that are known to increase transmissibility and virulence in mammals. Monitoring the spillover and adaptation of avian viruses in mammalian species is critically important if we are to understand the factors that lead to both epizootic and zoonotic emergence.

Hypoxic pulmonary vasoconstriction (HVC), an intrinsic and assumed ubiquitous response of mammalian pulmonary blood vessels, matches regional ventilation to perfusion via an unknown O₂-sensing mechanism. Global pulmonary hypoxia experienced by individuals suffering from chronic obstructive pulmonary disease or numerous hypoventilation syndromes, including sleep apnea, often produces maladaptive pulmonary hypertension, but pulmonary hypertension is not observed in diving mammals, where profound hypoxia is routine. Here we examined the response of cow and sea lion pulmonary arteries (PA) to hypoxia and observed the expected HVC in the former and a unique hypoxic vasodilation in resistance vessels in the latter. We then used this disparate response to examine the O₂-sensing mechanism. In both animals, exogenous H₂S mimicked the vasoactive effects of hypoxia in isolated PA. H₂S-synthesizing enzymes, cystathionine β-synthase, cystathionine γ-lyase, and 3-mercaptopyruvate sulfur transferase, were identified in lung tissue from both animals by one-dimensional Western blot analysis and immunohistochemistry. The relationship between H₂S production/consumption and O₂was examined in real time by use of amperometric H₂S and O₂sensors. H₂S was produced by sea lion and cow lung homogenate in the absence of O₂, but it was rapidly consumed when O₂was present. Furthermore, consumption of exogenous H₂S by cow lung homogenate, PA smooth muscle cells, and heart mitochondria was O₂dependent and exhibited maximal sensitivity at physiologically relevant Po₂levels. These studies show that HVC is not an intrinsic property of PA and provide further evidence for O₂-dependent H₂S metabolism in O₂sensing.

This study uses remote imaging technology to quantify, compare, and contrast the cephalic anatomy between a neonate female and a young adult male Cuvier's beaked whale. Primary results reveal details of anatomic geometry with implications for acoustic function and diving. Specifically, we describe the juxtaposition of the large pterygoid sinuses, a fibrous venous plexus, and a lipid‐rich pathway that connects the acoustic environment to the bony ear complex. We surmise that the large pterygoid air sinuses are essential adaptations for maintaining acoustic isolation and auditory acuity of the ears at depth. In the adult male, an acoustic waveguide lined with pachyosteosclerotic bones is apparently part of a novel transmission pathway for outgoing biosonar signals. Substitution of dense tissue boundaries where we normally find air sacs in delphinoids appears to be a recurring theme in deep‐diving beaked whales and sperm whales. The anatomic configuration of the adult male Ziphius forehead resembles an upside‐down sperm whale nose and may be its functional equivalent, but the homologous relationships between forehead structures are equivocal. Anat Rec, 291:353–378, 2008.