Applications and limitations of Micro-XCT imaging in the studies of Permian radiolarians: a new genus with bi-polar main spines

Microfocus X-ray Computed Tomography (micro-XCT) has been employed recently in radiolarian studies, though so far primarily to generate high quality tomographic images. Although micro-XCT technique cannot always produce high-quality tomographic images, it frequently can provide valuable information on the internal structure of spongy polycystines. Here we employ micro-XCT to understand internal skeletal structures of several Permian specimens of polycystine radiolarians. Structural inferences from micro-XCT images are compared to images of the same specimens made with SEM and transmitted light microscopy (TLM). The utility of micro-XCT for imaging internal structures is first confirmed by examining the spongy, flat, four-spined species Tetraspongodiscus stauracanthus. Micro-XCT method is then used to examine the internal structures of a spherical to elliptical polycystine with two bi-polar main spines, Dalongicaepa bipolaris Xiao and Suzuki gen. et sp. nov., from the Dalong Formation (Changhsingian) of South China. The new genus is characterized by four to seven densely concentric shells with a large spherical hollow in the center and two cylindrical spines at both poles of the cortical shell, and belongs to the family Spongotortilispinidae. Spherical to elliptical polycystines with bi-polar main spines are similar in external appearance, and their phylogenetic relationships are only determinable by examination of the internal structures. We therefore analyzed all Permian and Mesozoic spherical to elliptical polycystines with bi-polar main spines showing internal structures, using cluster analysis to measure similarity. The results show distinctive differences in internal structures and suggest that family level relationships should be revised in the future

A Morpho-molecular Perspective on the Diversity and Evolution of Spumellaria (Radiolaria)

Spumellaria (Radiolaria, Rhizaria) are holoplanktonic amoeboid protists, ubiquitous and abundant in the global ocean. Their silicified skeleton preserves very well in sediments, displaying an excellent fossil record extremely valuable for paleo-environmental reconstruction studies, from where most of their extant diversity and ecology have been inferred. This study represents a comprehensive classification of Spumellaria based on the combination of ribosomal taxonomic marker genes (rDNA) and morphological characteristics. In contrast to established taxonomic knowledge, we demonstrate that symmetry of the skeleton takes more importance than internal structures at high classification ranks. Such reconsideration allows gathering different morphologies with concentric structure and spherical or radial symmetry believed to belong to other Radiolaria orders from the fossil record, as for some Entactinaria families. Our calibrated molecular clock dates the origin of Spumellaria in the middle Cambrian (ca. 515 Ma), among the first radiolarian representatives in the fossil record. This study allows a direct connection between living specimens and extinct morphologies from the Cambrian, bringing both a standpoint for future molecular environmental surveys and a better understanding for paleo-environmental reconstruction analysis. (C) 2021 The Authors. Published by Elsevier GmbHThis work was supported by the IMPEKAB ANR 15-CE02-0011 grant and the Brittany Region ARED C16 1520A01, the Japan Society for Promotion of Science KAKENHI Grant No. K16K0-74750 for N. Suzuki and "the Cooperative Research Project with the Japan Science and Technology Agency (JST) and Centre National de la Recherche Scientifique (CNRS, France) "Morphomolecular Diversity Assessment of Ecologically, Evolutionary, and Geo-logically Relevant Marine Plankton (Radiolaria) ". We are grateful to the CNRS-Sorbonne University ABiMS bioinformatics platform (http://abims.sbroscoff.fr) for providing computational resources. The authors are grateful to the MOOSE observation national network (funded by CNRS-INSU and Research Infrastructure ILICO) which sustain the annual ship-based hydrographic sections in the northwestern Mediterranean Sea (MOOSEGE) , as well as John Dolan for hosting us multiple times at the Laboratoire d'Oceanographie of Villefranche sur Mer. We are greatly thankful to Cedric Berney for the phylogenetic advice and the valuable help on the interpretation of the "symbiotic" clade, as well as Vasily Zlatogursky for his contributions and feed-back on the heliozoan-like organism

Biology and Ecology of Radiolaria

Radiolaria are unicellular holoplanktonic protozoa with siliceous or strontium sulfate skeletons. Mainly studied by micropaleontologists because of their excellent fossil record, they are also key members of planktonic communities and play important roles in various oceanic ecosystems. This chapter presents an overview of the current knowledge on living Radiolaria (orders Acantharia, Collodaria, Nassellaria, Spumellaria and Taxopodia). Besides general considerations on Radiolaria as a whole, it focuses on the taxonomy, biology, and ecology of each radiolarian order. Finally this chapter provides insights on research perspectives to improve our knowledge of living radiolarians and their ecological role in marine ecosystems

Aulographis japonica sp. nov. (Phaeodaria, Aulacanthida, Aulacanthidae), an abundant zooplankton in the deep sea of the Sea of Japan

Zooplankton samples from the deep water of the Sea of Japan often contain yellowish semitransparent spheres (1.0–1.5 mm in diameter). We recognized these spheres as a single phaeodarian species (Cercozoa, Rhizaria) and described them as Aulographis japonica sp. nov. (family Aulacanthidae) in this paper. This species has a high abundance in the Japan Sea Proper Water (JSPW) and occasionally higher biomass than that of copepods. Molecular analysis based on 18S SSU rDNA revealed that Aulacantha scolymantha, which belongs to the same family as A. japonica, is closer to Aulosphaera trigonopa and Protocystis spp., which belong to different orders, than to the present species. The distribution of A. japonica is apparently restricted to low temperature water. Its biomass was the highest in the uppermost layer of JSPW, and this phaeodarian species was the second most important zooplankton below 250 m depth in terms of biomass among the total zooplankton groups. This is probably due to its generalist type of feeding. Considering its large biomass, A. japonica possibly plays an important role in matter cycles within the Sea of Japan

Quaternary radiolarian biostratigraphy of IODP Site 341-U1417A

Expedition 341 of the Integrated Ocean Drilling Program (IODP) retrieved sediment cores spanning the time interval between the Pleistocene and Miocene from the southern Gulf of Alaska. Onboard Pleistocene radiolarian biostratigraphy is hereby refined by increasing the sampling resolution. The 178 core samples from the upper 190 m CCSF-B of Site U1417 contained faunal elements similar to the Northwest Pacific; for example, the three biozones in the Northwest Pacific (i.e., Eucyrtidium matuyamai, Stylatractus universus and Botryostrobus aquilonaris) were also recognized in the Gulf of Alaska, spanning 1.80-1.13 Ma, 1.13-0.45 Ma, and the last 0.45 Myr, respectively. Based on the age model that we used in this study and the shipboard paleomagnetic reversal events, the first occurrences (FOs) of Amphimelissa setosa and Schizodiscus japonicus in the Northeast Pacific were preliminarily determined to be 1.48 and 1.30 Ma, respectively. The last occurrence (LO) of Eucyrtidium matuyamai and the FO of Lychnocanoma sakaii, both well-established bioevents in the Northwest Pacific, were dated at 0.80 Ma and 1.13 Ma, respectively. The LO of E. matuyamai is a synchronous event at 1.05±0.1 Ma in the North Pacific, while the FOs of A. setosa and S. japonicus are significantly older than what found elsewhere at 1.48 Ma and 1.30 Ma, respectively

A stereocontrolled construction of 2-azido-2-deoxy-1,2-cis-α-galactosidic linkages utilizing 2-azido-4,6-O-benzylidene-2-deoxygalactopyranosyl diphenyl phosphates: stereoselective synthesis of mucin core 5 and core 7 structures

TMSOTf-promoted glycosidation of 2-azido-4,6-O-benzylidene-2-deoxygalactosyl diphenyl phosphates with fluorenylmethoxycarbonyl (Fmoc)-protected serine and threonine derivatives in THF/Et2O (1:1) gave glycosyl amino acids in high yields and with excellent levels of α-selectivity (α/β=94:6-95:5). The synthetic utility of the present glycosidation method was demonstrated by a stereoselective synthesis of mucin-type glycopeptide core 5 and core 7 building blocks, which are suitable for Fmoc-based solid-phase synthesis of O-glycopeptides