Structure and growth pattern of the bizarre hemispheric prominence on the rostrum of the fossil beaked whale Globicetus hiberus (Mammalia,Cetacea, Ziphiidae)

The rostrum of most ziphiids (beaked whales) displays bizarre swollen regions, accompanied with extreme hypermineralisation and an alteration of the collagenous mesh of the bone. The functional significance of this specialization remains obscure. With the voluminous and dense hemispheric excrescence protruding from the premaxillae, the recently described fossil ziphiid Globicetus hiberus is the most spectacular case. This study describes the histological structure and interprets the growth pattern of this unique feature. Histologically, the prominence in Globicetus is made up of an atypical fibro‐lamellar complex displaying an irregular laminar organization and extreme compactness (osteosclerosis). Its development is suggested to have resulted from a protraction of periosteal accretion over the premaxillae, long after the end of somatic growth. Complex shifts in the geometry of this tissue are likely to have occurred during its accretion and no indication of Haversian remodeling could be found. X‐ray diffraction and Raman spectroscopy indicate that the bone matrix in the premaxillary prominence of Globicetus closely resembles that of the rostrum of the extant beaked whale Mesoplodon densirostris: apatite crystals are of common size and strongly oriented, but the collagenous meshwork within bone matrix seems to be extremely sparse. These morphological and structural data are discussed in the light of functional interpretations proposed for the highly unusual and diverse ziphiid rostrum. J. Morphol. 277:1292–1308, 2016. © 2016 Wiley Periodicals, Inc.     

A twofold role for global energy gradients in marine biodiversity trends

Explanations for major biodiversity patterns have not achieved a consensus, even for the latitudinal diversity gradient (LDG), but most relate to patterns of solar energy influx into Earth systems, and its effects on temperature (as biochemical activity rates are temperature sensitive) and photosynthesis (which drives nearly all of the productivity that fuels ecosystems). Marine systems break some of the confounding correlations among temperature, latitude and biodiversity that typify the terrestrial systems that have dominated theoretical discussions and large‐scale analyses. High marine diversities occur not only in warm shallow seas where productivity may be either low or high, depending on regional features, but also in very cold deep‐sea regions, indicating that diversity is promoted by stability in temperature and in trophic resources (nutrients and food items), and more specifically by their interaction, rather than by high mean values of either variable. The common association of high diversity with stable but low to moderate annual productivity suggests that ecological specialization underlies the similarly high diversities in the shallow tropics and deep sea. Recent work on shallow‐marine bivalves is consistent with this view of decreasing specialization in less stable habitats. Lower diversities in shallow seas are associated with either high thermal seasonality (chiefly in temperate latitudes) or highly seasonal trophic supplies (at any latitude), which exclude species that are adapted to narrow ranges of those variables.     

Deep mutational scanning identifies SARS-CoV-2 Nucleocapsid escape mutations of currently available rapid antigen tests

1. Download : Download high-res image (239KB)
2. Download : Download full-size image

     

Functional diversity for body actions in the mesencephalic locomotor region

1. Download : Download high-res image (240KB)
2. Download : Download full-size image

     

Novel summary metrics for insular biotic assemblages based on taxonomy and phylogeny: Biogeographical,palaeogeographical and possible conservational applications

Using the land‐bound vertebrates on the marine islands as model organisms, two metrics are presented that permit quantitative and succinct synopses of the ‘evolutionary maturity’ of the hosted faunal assemblages. In turn, these reflect the geo‐physical settings and geological developments of the substrates. The assemblage lineage‐taxonomy spectrum (ALTS) is based on the constituent lineages’ taxonomic distinctiveness and diversity. Individual lineages within assemblages can in most cases be assigned to one of six categories, LT1?LT6: LT1 is a non‐endemic taxon, whereas LT6 comprises multiple endemic genera from a family that arose elsewhere. If required, the scheme can be expanded: LT9 is an endemic order. The data can then be combined to provide an assemblage spectrum, for example, 00:08:38:30:08:15[ 13 ]. Here, the first six values denote the number of lineages assigned to each category expressed as percentages of the overall total, with the sum of the processed lineages listed as the seventh (in brackets and bold). The ALTS metric highlights efficiently the key features of a marine island's biological assemblage. Notably, the contrast between spectra for suites on geologically and geo‐physically varied island types can be striking, for instance the squamate suite on the young, proximate orogenic margin island of Taiwan is coded 78:16:05:00:00:00[ 37 ] whereas the one on the distantly located, Late Eocene composite terrane island of New Caledonia is 00:11:00:11:33:44[ 9 ]. To overcome the subjectivity that is inherent in assigning supraspecific ranks, an alternative assemblage lineage‐age spectrum (ALAS) is also introduced that makes use of the binary logarithm values of the colonization times of the island lineages (0–2, 2–4, … , 32–64, >64 Ma). It is represented using a seven‐plus‐two‐number code, for instance Madagascar's squamates are 00:06:00:00:19:62:12[ 19 ( 16 )]; most colonizations took place in the Palaeogene (66–23 Ma); there are 19 lineages, but only 16 are presently age‐dated. In addition to marine‐island biogeography studies, the ALTS–ALAS spectrum approach is potentially useful for encapsulating biotas in other sorts of insular setting (e.g. lakes, mountain tops), and for evaluating palaeogeographical models. Furthermore, it may help emphasize the conservation value of an island's faunal assemblage.     

Reliability of wavefront shaping based on coherent optical adaptive technique in deep tissue focusing

Wavefront shaping can compensate the wavefront distortions in deep tissue focusing, leading to an improved penetration depth. However, when using the backscattered signals as the feedback, unexpected compensation bias may be introduced, resulting in focusing position deviations or even no focus in the illumination focal plane. Here we investigated the reliability of wavefront shaping based on coherent optical adaptive technique in deep tissue focusing by measuring the position deviations between the foci in the illumination focal plane and the epi‐detection plane. The experimental results show that when the penetration depth reaches 150 μm in mouse brain tissue (with scattering coefficient ~22.42 mm^?1) using a 488 nm laser and an objective lens with 0.75 numerical aperture, the center of the real focus will deviate out of one radius range of the Airy disk while the optimized focus in the epi‐detection plane maintained basically at the center. With the penetration depth increases, the peak to background ratio of the focus in the illumination focal plane decreases faster than that in the epi‐detection plane. The results indicate that when the penetration depth reaches 150 μm, feedback based on backscattered signals will make wavefront shaping lose its reliability, which may provide a guidance for applications of non‐invasive precise optogenetics or deep tissue optical stimulation using wavefront shaping methods. A, Intensity distribution in the epi‐detection plane and the illumination focal plane before and after correction, corresponding to brain sections with 250 and 300 μm thickness, respectively. Scale bar is 2 μm. B, Averaged focusing deviations in the epi‐detection plane (optimized) and the illumination focal plane (monitored) after compensation. The unit of the ordinate is one Airy disk diameter. Black dashed line represents one Airy disk radius. Bars represent the SE of each measurement set.      

Spatial and temporal patterns of genetic variation in the widespread antitropical deep‐sea coral Paragorgia arborea

Numerous deep‐sea species have apparent widespread and discontinuous distributions. Many of these are important foundation species, structuring hard‐bottom benthic ecosystems. Theoretically, differences in the genetic composition of their populations vary geographically and with depth. Previous studies have examined the genetic diversity of some of these taxa in a regional context, suggesting that genetic differentiation does not occur at scales of discrete features such as seamounts or canyons, but at larger scales (e.g. ocean basins). However, to date, few studies have evaluated such diversity throughout the known distribution of a putative deep‐sea species. We utilized sequences from seven mitochondrial gene regions and nuclear genetic variants of the deep‐sea coral Paragorgia arborea in a phylogeographic context to examine the global patterns of genetic variation and their possible correlation with the spatial variables of geographic position and depth. We also examined the compatibility of this morphospecies with the genealogical‐phylospecies concept by examining specimens collected worldwide. We show that the morphospecies P. arborea can be defined as a genealogical‐phylospecies, in contrast to the hypothesis that P. arborea represents a cryptic species complex. Genetic variation is correlated with geographic location at the basin‐scale level, but not with depth. Additionally, we present a phylogeographic hypothesis in which P. arborea originates from the North Pacific, followed by colonization of the Southern Hemisphere prior to migration to the North Atlantic. This hypothesis is consistent with the latest ocean circulation model for the Miocene.     

Rare and new cumaceans (Crustacea,Peracarida) from?the southern margin of the Cap Ferret Canyon (Bay of Biscay)

A new cumacean genus and species, Ithyleucon sorbei gen. et sp. n., was described from material collected in the southern margin of the Cap Ferret Canyon (Bay of Biscay, NE Atlantic). Although the new genus resembles Pseudoleucon Zimmer, 1903, in terms of the general aspect of the carapace and the pseudo-rostrum position, it shows important differences in the uropod structure and in the size of the antenna 1 accessory flagellum. In addition, some comments regarding the morphology of certain rare species (Mesolamprops denticulatus Ledoyer, 1983, Hemilamprops normani Bonnier, 1896 and Schizocuma spino-culatum (Jones, 1984)) are also provided.     

Clones or clans: the genetic structure of a deep‐sea sponge,Aphrocallistes vastus,in unique sponge reefs of British Columbia,Canada

Understanding patterns of reproduction, dispersal and recruitment in deep‐sea communities is increasingly important with the need to manage resource extraction and conserve species diversity. Glass sponges are usually found in deep water (>1000 m) worldwide but form kilometre‐long reefs on the continental shelf of British Columbia and Alaska that are under threat from trawling and resource exploration. Due to their deep‐water habitat, larvae have not yet been found and the level of genetic connectivity between reefs and nonreef communities is unknown. The genetic structure of Aphrocallistes vastus, the primary reef‐building species in the Strait of Georgia (SoG) British Columbia, was studied using single nucleotide polymorphisms (SNPs). Pairwise comparisons of multilocus genotypes were used to assess whether sexual reproduction is common. Structure was examined 1) between individuals in reefs, 2) between reefs and 3) between sites in and outside the SoG. Sixty‐seven SNPs were genotyped in 91 samples from areas in and around the SoG, including four sponge reefs and nearby nonreef sites. The results show that sponge reefs are formed through sexual reproduction. Within a reef and across the SoG basin, the genetic distance between individuals does not vary with geographic distance (r = ?0.005 to 0.014), but populations within the SoG basin are genetically distinct from populations in Barkley Sound, on the west coast of Vancouver Island. Population structure was seen across all sample sites (global F_ST = 0.248), especially between SoG and non‐SoG locations (average pairwise F_ST = 0.251). Our results suggest that genetic mixing occurs across sponge reefs via larvae that disperse widely.     

A functional nanocarrier that copenetrates extracellular matrix and multiple layers of tumor cells for sequential and deep tumor autophagy inhibitor and chemotherapeutic delivery

To further enhance the intensity of deep tumor drug delivery and integrate a combined therapy, we herein report on a core-shell nanocarrier that could simultaneously overcome the double barriers of the extracellular matrix (ECM) and multiple layers of tumor cells (MLTC). A pH-triggered reversible swelling-shrinking core and an MMP2 (matrix metallopeptidase 2) degradable shell were developed to encapsulate chemotherapeutics and macroautophagy/autophagy inhibitors, respectively. MMP2 degraded the shell, which was followed by the autophagy inhibitors' release. The exposed core could diffuse along the pore within the ECM to deliver chemotherapeutics into deep tumors, and it was able to swell in lysosomes and shrink back in the cytoplasm or ECM. The swelling of the core resulted in the rapid release of chemotherapeutics to kill autophagy-inhibited cells. After leaving the dead cells, the shrinking core could act on neighboring cells that were closer to the center of the tumor. The core thus could also cross MLTC layer by layer to deliver chemotherapeutics into the deep tumor.