A eukaryote assemblage intercalated with Marinoan glacial deposits in South Australia

Video of digital X-ray tomographs (µCT) in longitudinal plane through cylinder of siltstone, maximum diameter seen (left to right when viewing movie) is 5.4m

A New Method for Morphometric Analysis of Tissue Distribution of Mobile Cells in Relation to Immobile Tissue Structures

The distribution of cells in stained tissue sections provides information that may be analyzed by means of morphometric computation. We developed an algorithm for automated analysis for the purpose of answering questions pertaining to the relative densities of wandering cells in the vicinity of comparatively immobile tissue structures such as vessels or tumors. As an example, we present the analysis of distribution of CD56-positive cells and of CXCR3-positive cells (relative densities of peri-vascular versus non-vascular cell populations) in relation to the endothelium of capillaries and venules of human parietal decidua tissue of first trimester pregnancy. In addition, the distibution of CD56-positive cells (mostly uterine NK cells) in relation to spiral arteries is analyzed. The image analysis is based on microphotographs of two-color immunohistological stainings. Discrete distances (10–50 µm) from the fixed structures were chosen for the purpose of definining the extent of neighborhood areas. For the sake of better comparison of cell distributions at different overall cell densities a model of random distribution of “cells” in relation to neighborhood areas and rest decidua of a specific sample was built. In the chosen instances, we found increased perivascular density of CD56-positive cells and of CXCR3-positive cells. In contrast, no accumulation of CD56-positive cells was found in the neighborhood of spiral arteries

Activating KIR and HLA Bw4 Ligands Are Associated to Decreased Susceptibility to Pemphigus Foliaceus, an Autoimmune Blistering Skin Disease

The KIR genes and their HLA class I ligands have thus far not been investigated in pemphigus foliaceus (PF) and related autoimmune diseases, such as pemphigus vulgaris. We genotyped 233 patients and 204 controls for KIR by PCR-SSP. HLA typing was performed by LABType SSO reagent kits. We estimated the odds ratio, 95% confidence interval and performed logistic regression analyses to test the hypothesis that KIR genes and their known ligands influence susceptibility to PF. We found significant negative association between activating genes and PF. The activating KIR genes may have an overlapping effect in the PF susceptibility and the presence of more than three activating genes was protective (OR = 0.49, p = 0.003). A strong protective association was found for higher ratios activating/inhibitory KIR (OR = 0.44, p = 0.001). KIR3DS1 and HLA-Bw4 were negatively associated to PF either isolated or combined, but higher significance was found for the presence of both together (OR = 0.34, p<10−3) suggesting that the activating function is the major factor to interfere in the PF pathogenesis. HLA-Bw4 (80I and 80T) was decreased in patients. There is evidence that HLA-Bw4(80T) may also be important as KIR3DS1 ligand, being the association of this pair (OR = 0.07, p = 0.001) stronger than KIR3DS1-Bw4(80I) (OR = 0.31, p = 0.002). Higher levels of activating KIR signals appeared protective to PF. The activating KIR genes have been commonly reported to increase the risk for autoimmunity, but particularities of endemic PF, like the well documented influence the environmental exposure in the pathogenesis of this disease, may be the reason why activated NK cells probably protect against pemphigus foliaceus

Sea ice-free conditions during the Sturtian glaciation (early Cryogenian), South Australia

In the Neoproterozoic snowball Earth hypothesis, shutdown of the planet’s hydrological system has been attributed to a global ice cover during one or more extreme glaciations. In the central Flinders Ranges, South Australia, the Yudnamutana Subgroup of Sturtian age includes diamictite, sandstone, and siltstone units of glaciomarine origin as much as 5000 m thick, and is overlain by postglacial transgressive siltstone and shale of the Tindelpina Shale Member, Tapley Hill Formation. In the central Flinders Ranges, the Yudnamutana Subgroup consists of (1) the Pualco Tillite (gravity resedimented glacial deposits), (2) the Holowilena Ironstone (glacioturbidites), (3) poorly stratified pebbly diamictite of the Warcowie Dolomite Member, lowermost Wilyerpa Formation (gravity resedimented glacial deposits), succeeded by (4) siltstones and sandstones with abundant hummocky cross-stratification (HCS: storm deposits), and (5) a lonestone-bearing succession with cobble-sized clasts in the upper Wilyerpa Formation (ice-rafted debris interpreted to record a glacial re-advance) in which HCS is absent. Because the action of oscillating waves is required to produce HCS on the seafl oor, its presence indicates an interval of significant meltback prior to glacial re-advance. Given that the HCS occurs ~2 km beneath the Tindelpina Shale Member, it signifies a major ice-free interval during the Sturtian glaciation.Daniel Paul Le Heron, Grant Cox, Anita Trundley, and Alan Collin

Two Cryogenian glacial successions compared: Aspects of the Sturt and Elatina sediment records of South Australia

Two Cryogenian glacial sequences, the Sturt and Elatina, occur within the Adelaide Rift Complex, S Australia, and are part of an ∼8. km thick succession recording Rodinia fragmentation and subsequent passive margin development. We compare and contrast these glacial successions, presenting new data, including detailed logged sections, for both glacial sequences. Facies analysis reveals a total of six facies associations, recording a range of glacial and glacially related processes. These are a diamictite facies association (ice-proximal debris flows), a sheet sandstone facies association (fluvial deposits), a flaser and rhythmically bedded facies association (tidal flat), a hummocky cross-stratified sandstone facies association (shoreface to offshore transition zone deposits) and an underflow facies association (recording offshore deposition). A sixth facies association, a ferruginous lonestone-bearing siltstone, is restricted to the top of the Elatina Formation and records rapid environmental amelioration and emergence from glaciation. In the central Flinders Ranges, the Sturt succession commences with a glacial erosion surface (GES), which in agreement with previous workers, was probably enhanced by rifting. This GES is overlain, in ascending order, by the Pualco Tillite, Holowilena Ironstone and Wilyerpa Formation, with the Warcowie Dolomite Member at the base of this latter formation. A second GES is preserved within this latter unit, and is overlain by a stratigraphic motif that records an alternation of offshore transition zone and offshore deposits. Significant base level falls within the Wilyerpa Formation are identified by fluvial deposits sitting disconformably upon offshore deposits. In contrast, within the Elatina Formation, a single GES is proposed, which defines the base of the formation. The Elatina Formation is split into two informal members on the basis of analysis of sediment stacking patterns and the recognition of a sharp stratigraphic surface that divides the formation. Apart from a locally preserved basal diamictite, the lower member consists of fluvial deposits, whereas the upper member is dominated by a mixture of tidal flat sediments and debris flow deposits. The boundary between these units is therefore interpreted as a hybrid surface recording tidal ravinement in some areas and a glacial advance in others. Deglaciation left contrasting deposits: the Sturt deglaciation culminated in deposition of black shale of the Tindelpina Shale Member of the Tapley Hill Formation, seemingly as a sheet-like deposit over the Adelaide Rift Complex and beyond into the Amadeus Basin of central Australia. The Elatina deglaciation, meanwhile, began first with deposition of the sixth facies association (ferruginous dropstone-bearing siltstone), then proceeded with deposition of cap dolostone of the Nuccaleena Formation. © 2011 Elsevier B.V.Daniel Paul Le Heron, Grant Cox, Anita Trundley and Alan S. Collinshttp://www.elsevier.com/wps/find/journaldescription.cws_home/503357/description#descriptio

Conformation of human leucocyte antigen-C molecules at the surface of human trophoblast cells

Human leucocyte antigen (HLA)-C is expressed at lower levels than other classical HLA-I molecules on somatic cells. Surface HLA-C proteins can occur as conventionally β2-microglobulin (β2m)-associated complexes or as open conformers dissociated from peptide and/or β2m. We investigated the conformation of HLA-C molecules on normal human trophoblast cells, which invade the maternal decidua during placentation. A panel of monoclonal antibodies to different conformations of HLA-I molecules was used in flow cytometry and surface immunoprecipitation experiments. On the surface of trophoblast cells only β2m-associated complexes of HLA-C molecules were detected. In contrast, both open conformers and β2m-associated HLA-C could be detected on other cells from the decidua, HLA-C-transfectants and cell lines. The levels of HLA-C expressed on primary trophoblast cells could be detected by antibodies specific to non-β2m-associated conformations because binding was seen after acid-induced denaturation of surface proteins. In contrast to HLA-G molecules on trophoblasts, we found no evidence for the presence of disulphide-linked multimers of HLA-C complexes. These results show that most HLA-C molecules present at the trophoblast cell surface are in the conventional β2m-associated conformation. These findings have implications regarding the stability of trophoblast HLA-C molecules and how they interact with receptors on decidual leucocytes during placentation