Skeletal Nets of the Ediacaran Fronds

The Ediacara fauna is traditionally regarded as the first complex, diverse and widespread macroscopic life. The uncertainty of systematic position of its members has led to very different views on the early evolution of metazoans. In part, this may be due to a lack of data on sclerotization: a hard skeleton is a part of the archetype of the most taxa known from the fossil record, whereas the Ediacara fauna as a whole is most often considered soft-bodied, which complicates comparison. Here we report the Late Precambrian frond-like fossils (Petalonamae) from the Vendian assemblage of the Southeastern White Sea area (∼555.3 Ma), which show evidence of elaborate skeleton composed of a regular meshwork reinforced by dense longitudinal and circular bands. Judging from the nature of preservation and the dynamics of the environment Ediacaran fronds secreted a relatively rigid but flexible skeleton. The fact that frond-like Petalonamae had a supporting structure similar to that of sponges and cnidarians seems to be a powerful argument in favor of their metazoan affinity. The new observations indicated also that the widespread skeletonization had occurred long before the “Cambrian skeletal revolution”.     

A new sauropod dinosaur from the Lower Cretaceous Ilek Formation,Western Siberia,Russia

Sibirotitan astrosacralis nov. gen., nov. sp., is described based on isolated but possibly associated cervical and dorsal vertebrae, sacrum, and previously published pedal elements from the Lower Cretaceous (Barremian?) Ilek Formation at Shestakovo 1 locality (Kemerovo Province, Western Siberia, Russia). Some isolated sauropod teeth from the Shestakovo 1 locality are referred to the same taxon. The phylogenetic parsimony analyses place Sibirotitan astrosacralis nov. gen., nov. sp., as a non-titanosaurian somphospondyl titanosauriform. The new taxon exhibits four titanosauriform and one somphospondylan synapomorphies, and one autapomorphy – a hyposphene ridge that extends between the neural canal and the postzygapophyses. It differs from all other Somphospondyli by having only five sacral vertebrae. The new taxon shares with Euhelopus and Epachtosaurus sacral ribs that converge towards the middle of the sacrum in dorsal view. Sibirotitan astrosacralis nov. gen., nov. sp., is only the second sauropod taxon from Russia and one of the oldest titanosauriform described so far in Asia.     

Elucidating Ernietta: new insights from exceptional specimens in the Ediacaran of Namibia

Exceptionally preserved specimens of Ernietta in a shallow‐marine gutter cast from southern Namibia reveal that all previously figured specimens of this iconic Ediacaran megafossil are incomplete, representing only the base of a larger and more complex organism. The complete organism is interpreted as comprising a buried, sand‐filled anchor exhibiting the classical Ernietta morphology that passes distally into a trunk that is crowned by two facing fans that extended into the overlying water column. All parts of Ernietta, from the base of its buried anchor to the tip of its fans, appear to have been composed of a palisade of tubular elements that have been variably preserved. Similarity of tubule morphology despite the inherent difference in function between these constructions supports the view that these tubes were integral to all anatomical parts and functions of Ernietta. This style of architecture, construction and function is unique to the Erniettomorpha, supporting the view that it represents an extinct Ediacaran clade in the early evolution of multi‐cellular life.     

Restoration of hypothalamic signaling systems as a cause of improved metabolic parameters in rats with neonatal diabetes model during treatment with bromocriptine mesylate

One approach to correction of diabetes mellitus 2 type (DM2) and its complications is the use of bromocriptine mesylate (BCM), a selective agonist of the dopamine receptor type 2 (DA₂R). However, the effectiveness and mechanisms of the action of BCM in the treatment of severe forms of DM2 forms currently not understood. The purpose of this study was to investigate the influence of 4-week treatment of male rats with neonatal DM2 model using BCM (300 mg/kg daily) on their metabolic parameters and on the activity of the adenylyl cyclase signaling system (ACSS) in the hypothalamus. Exposure to BCM restored glucose tolerance and glucose utilization by exogenous insulin, normalized lipid metabolism, and lowered triglycerides and atherogenic cholesterol levels, which are elevated in DM2. In the hypothalamus of diabetic rats treated with BCM, the regulation of ACSS by agonists of melanocortin receptors type 4 (MC₄R), DA₂R, and serotonin 1B-subtype receptors and expression of the Mc4r gene encoding MC₄R were restored. Furthermore, BCM treatment did not influence the insulin levels in the blood and its production by pancreatic β-cells. The data indicate that the use of BCM to correct severe forms of experimental DM2 holds promise and show that the therapeutic potential of this drug is based on its ability to restore signaling systems of the hypothalamus that are sensitive to monoamines and peptides of the melanocortin family, which are responsible for the control of energy metabolism and insulin sensitivity.     

Characterizations of the murine mesenchymal cell line expressing GFP

We established and characterized a murine mesenchymal stem cell line from the bone marrow of a transgenic C57BL mouse that ubiquitously expressed green fluorescent protein (GFP). Immunostaining revealed the presence of several markers common for mesenchymal stem cells (MSCs). The cells expressed specific fibroblast proteins, such as smooth muscle actin, which is localized in stress fibrils, and vimentin, a major protein of intermediate filaments in connective tissue cells. These proteins are responsible for the ability to differentiate into adipocytes or osteoblasts under appropriate conditions. The MSC karyotype was unstable. At the 6th passage cells, were aneuploid and genetically heterogeneous. The number of chromosomes ranged from near 2n to 8n. 80% of cells had chromosome numbers between 50 and 85 without a well-defined modal class. Differential G-staining of metaphase spreads showed variability in the copy numbers of individual chromosomes and presence of random chromosome rearrangements, such as ectopic associations of nonhomologous chromosomes. All cells analyzed contained a single dicentric marker chromosome. Some cells also had mini-chromosomes regarded as indicators of gene amplification. We suppose that the karyotypic instability of MSCs that express GFP is provoked by the insertion of foreign GFP transgenes into the murine genome. These cells could be useful for the study of genomic alterations during the spontaneous oncogenic transformation of stem cells.     

Feeding traces of proarticulata—the Vendian metazoa

Three types of low-topography impressions are described from the Late Vendian, which are interpreted as the feeding traces of representatives of the phylum Proarticulata Fedonkin, 1985, which became extinct in the Precambrian. The producers of two types of trace were found. Impressions are usually large and arranged in groups; therefore their correct interpretation only became possible following large-scale excavation work that was carried out for the first time in the Late Vendian deposits of the Arkhangelsk Region in 1996–2001. The single trace (or trace platform) represents a copy of the whole ventral side of the body made by sandstone or only the part of it. Usually trace platforms are arranged in chains and orientated in one distinct direction. In spite of some superficial similarity, the fossils are neither body remains nor traces of post-mortem compression. The hypothesis of trace formation proposed suggests that the feeding strategy of Proarticulata was different from any feeding behavior known in large Phanerozoic animals. All types of imprints are identified as belonging to the genus Epibaion Ivantsov, 2002. It is proposed that the Australian fossil Phyllozoon Jenkins et Gehling, 1978 is also a feeding trace of Proarticulata.     

The first dinosaur egg from the Lower Cretaceous of Western Siberia,Russia

The Lower Cretaceous Ilek Formation in Western Siberia (Russia) has yielded various vertebrate fossils, including skeletal remains of dinosaurs. Here we report on a fragmentary theropod egg from the vertebrate locality Shestakovo 3 of the Ilek Formation in Kemerovo Province. We assign the specimen to the oogenus Prismatoolithus (oofamily Prismatoolithidae) as Prismatoolithus ilekensis oosp. nov., on the basis of the following unique combination of characters: ovoid-shaped egg; thin eggshell 300–330 μm thick; angustiprismatic morphotype; eggshell with three different layers; gradual transition between mammillary layer and prismatic layer; abrupt contact between prismatic layer and external layer; mammillary layer to prismatic layer to external layer thickness ratio is 1:3:0.6; prismatic layer with ill-defined squamatic texture; angusticanaliculate pore system; and smooth outer surface. Like other Early Creataceous Prismatoolithus, the egg of Prismatoolithus ilekensis oosp. nov. was laid by a small bodied theropod dinosaur (troodontid or primitive bird) and this taxonomic attribution is supported by results of our phylogenetic analysis. Prismatoolithus ilekensis oosp. nov. is the first Early Cretaceous ootaxon from Russia.

urn:lsid:zoobank.org:act:734EAD40-86C3-488B-A61E-B5FF7378BC0E     

Novel human embryonic stem cell lines C612 and C910

Novel human embryonic stem cell lines C612 and C910 have been established from atching blastocytes. Cells were cultivated in mTeSR medium on a mouse fibroblast feeder layer; they exhibit common pluripotent markers, such as alkaline phosphatase, Oct 3/4, SSEA-4, Nanog, Rex1. The immunophenotyping of these cells by flow cytometry revealed CD90 (Thy-1) and CD117 (c-kit) antigens and showed weak or no expression of CD13, CD34, CD45, CD130, and HLA class I and II antigens, which is typical for human embryonic stem cells. Karyotypic structure of C612 and C910 assayed by the G-banding of metaphase plates is normal in both chromosome number and structure. The cells generate embryoid bodies, undergo spontaneous differentiation, and express three germ-layer markers (nestin, keratin, vimentin ectoderm), α-fetoprotein (entoderm), muscle α-actinin (mesoderm), i.e., possess pluripotent potency. Thus, C612 and C910 display accepted human embryonic stem cell properties, including unlimited self-renewal, expression of pluripotent markers, ability to differentiate into three germ layers, and are diploid; therefore, they may be of potential use for fundamental research, as well as for replacement therapy studies.     

Fedomia mikhaili—A new spicule-bearing organism of sponge grade from the Vendian (Ediacaran) of the White Sea, Russia

The Vendian fossil locality on the Solza River is one of the most productive in the White Sea Region. The fossiliferous deposits belong to the Upper Vendian Verkhovka Formation correlated lithologically with strata dated at 558 ± 1 to 555.3 ± 0.3 Ma in adjacent regions. This locality is characterized by yielding more than 10 well-represented Ediacaran genera. Elongated imprints of Fedomia mikhaili, n. gen. et n. sp., are common at the Solza River fossil locality. The new taxon is characterized by its six- to eight-rayed star-shaped concave structures with diameters of 2–5 mm. The organism can be reconstructed with sacciform thin-walled body attached basally to the substrate. The star-shaped structures may be spicules that appear to be rather flexible than rigid. The new genus, Fedomia, shows some similarities to Eiffelia Walcott, 1920 from the Middle Cambrian of British Columbia, and thus is interpreted as an organism of sponge grade. The new taxon could represent an additional phylogenetic link between the Ediacaran and Cambrian worlds.     

Growth variability in the late Vendian problematics <Emphasis Type="Italic">Parvancorina</Emphasis> Glaessner

Morphological and quantitative characteristics of the growth variability of two Parvancorina species were analyzed based on new abundant material from the Vendian of the White Sea. Growth variability in this problematic taxon appears to be wider than previously suggested. We found allometric growth in the White Sea population of P. minchami Glaessner, 1958, in contrast to isometric growth in Australian representatives of the species. Another White Sea species, P. sagitta Ivantsov, 2004, shows gradual formation of anchor-shaped structure in juveniles. Based on Australian material, it was previously believed that this structure did not change during ontogeny. These two distinctive features together with a strong variability of age-related measurements distinguish Parvancorina from other early arthropods (Scania, Primicaris), and cast doubt on the growth pattern as an argument in favor of the arthropodan nature of Parvancorina.