A new stem group echinoid from the Triassic of China leads to a revised macroevolutionary history of echinoids during the end-Permian mass extinction.

The Permian-Triassic bottleneck has long been thought to have drastically altered the course of echinoid evolution, with the extinction of the entire echinoid stem group having taken place during the end-Permian mass extinction. The Early Triassic fossil record of echinoids is, however, sparse, and new fossils are paving the way for a revised interpretation of the evolutionary history of echinoids during the Permian-Triassic crisis and Early Mesozoic. A new species of echinoid, Yunnanechinus luopingensis n. sp. recovered from the Middle Triassic (Anisian) Luoping Biota fossil Lagerstätte of South China, displays morphologies that are not characteristic of the echinoid crown group. We have used phylogenetic analyses to further demonstrate that Yunnanechinus is not a member of the echinoid crown group. Thus a clade of stem group echinoids survived into the Middle Triassic, enduring the global crisis that characterized the end-Permian and Early Triassic. Therefore, stem group echinoids did not go extinct during the Palaeozoic, as previously thought, and appear to have coexisted with the echinoid crown group for at least 23 million years. Stem group echinoids thus exhibited the Lazarus effect during the latest Permian and Early Triassic, while crown group echinoids did not.

Exceptional appendage and soft-tissue preservation in a Middle Triassic horseshoe crab from SW China.

Horseshoe crabs are classic "living fossils", supposedly slowly evolving, conservative taxa, with a long fossil record back to the Ordovician. The evolution of their exoskeleton is well documented by fossils, but appendage and soft-tissue preservation is extremely rare. Here we analyse details of appendage and soft-tissue preservation in Yunnanolimulus luopingensis, a Middle Triassic (ca. 244 million years old) horseshoe crab from Yunnan Province, SW China. The remarkable preservation of anatomical details including the chelicerae, five pairs of walking appendages, opisthosomal appendages with book gills, muscles, and fine setae permits comparison with extant horseshoe crabs. The close anatomical similarity between the Middle Triassic horseshoe crabs and their recent analogues documents anatomical conservatism for over 240 million years, suggesting persistence of lifestyle. The occurrence of Carcinoscorpius-type claspers on the first and second walking legs in male individuals of Y. luopingensis indicates that simple chelate claspers in males are plesiomorphic for horseshoe crabs, and the bulbous claspers in Tachypleus and Limulus are derived.

The oldest known digestive system consisting of both paired digestive glands and a crop from exceptionally preserved trilobites of the Guanshan Biota (Early Cambrian, China).

The early Cambrian Guanshan biota of eastern Yunnan, China, contains exceptionally preserved animals and algae. Most diverse and abundant are the arthropods, of which there are at least 11 species of trilobites represented by numerous specimens. Many trilobite specimens show soft-body preservation via iron oxide pseudomorphs of pyrite replacement. Here we describe digestive structures from two species of trilobite, Palaeolenus lantenoisi and Redlichia mansuyi. Multiple specimens of both species contain the preserved remains of an expanded stomach region (a "crop") under the glabella, a structure which has not been observed in trilobites this old, despite numerous examples of trilobite gut traces from other Cambrian Lagerstätten. In addition, at least one specimen of Palaeolenus lantenoisi shows the preservation of an unusual combination of digestive structures: a crop and paired digestive glands along the alimentary tract. This combination of digestive structures has also never been observed in trilobites this old, and is rare in general, with prior evidence of it from one juvenile trilobite specimen from the late Cambrian Orsten fauna of Sweden and possibly one adult trilobite specimen from the Early Ordovician Fezouata Lagerstätte. The variation in the fidelity of preservation of digestive structures within and across different Lagerstätten may be due to variation in the type, quality, and point of digestion of food among specimens in addition to differences in mode of preservation. The presence and combination of these digestive features in the Guanshan trilobites contradicts current models of how the trilobite digestive system was structured and evolved over time. Most notably, the crop is not a derived structure as previously proposed, although it is possible that the relative size of the crop increased over the evolutionary history of the clade.

A gigantic nothosaur (Reptilia: Sauropterygia) from the Middle Triassic of SW China and its implication for the Triassic biotic recovery.

The presence of gigantic apex predators in the eastern Panthalassic and western Tethyan oceans suggests that complex ecosystems in the sea had become re-established in these regions at least by the early Middle Triassic, after the Permian-Triassic mass extinction (PTME). However, it is not clear whether oceanic ecosystem recovery from the PTME was globally synchronous because of the apparent lack of such predators in the eastern Tethyan/western Panthalassic region prior to the Late Triassic. Here we report a gigantic nothosaur from the lower Middle Triassic of Luoping in southwest China (eastern Tethyan ocean), which possesses the largest known lower jaw among Triassic sauropterygians. Phylogenetic analysis suggests parallel evolution of gigantism in Triassic sauropterygians. Discovery of this gigantic apex predator, together with associated diverse marine reptiles and the complex food web, indicates global recovery of shallow marine ecosystems from PTME by the early Middle Triassic.

Nothosaur foraging tracks from the Middle Triassic of southwestern China.

The seas of the Mesozoic (266-66 Myr ago) were remarkable for predatory marine reptiles, but their modes of locomotion have been debated. One problem has been the absence of tracks, although there is no reason to expect that swimmers would produce tracks. We report here seabed tracks made by Mesozoic marine reptiles, produced by the paddles of nothosaurs (Reptilia, Sauropterygia) in the Middle Triassic of the Luoping localities in Yunnan, southwestern China. These show that the track-making nothosaurs used their forelimbs for propulsion, they generally rowed (both forelimbs operating in unison rather than alternately), and the forelimb entered medially, dug in as the paddle tip gained purchase, and withdrew cleanly. These inferences may provide evidence for swimming modes, or it could be argued that the locomotory modes indicated by the tracks were restricted to such contact propulsion. Such punting behaviour may have been used to flush prey from the bottom muds.

Complexity and diversity of eyes in early Cambrian ecosystems.

Here we report exceptionally preserved non-biomineralized compound eyes of a non-trilobite arthropod Cindarella eucalla from the lower Cambrian Chengjiang Lagerstätte, China. The specimen represents the oldest microanatomical evidence confirming the occurrence of highly developed vision in the early Cambrian, over 2,000 ommatidia in each eye. Moreover, a quantitative analysis of the distribution of eyes related to life habit, feeding types, and phyla respectively, from the Chengjiang biota indicates that specimens with eyes mostly belong to the arthropods, and they usually were actively mobile epifaunal and nektonic forms as hunters or scavengers. Arthropods took the lead in evolution of 'good vision' and domination in Cambrian communities, which supports the hypothesis that the origin and evolution of 'good vision' was a key trait that promoted preferential diversification and formed the foundation of modern benthic ecosystems in the early Cambrian ocean.

The unique invention of the siliceous sponges: their enzymatically made bio-silica skeleton.

Sponges are sessile filter feeders that, among the metazoans, evolved first on Earth. In the two classes of the siliceous sponges (the Demospongiae and the Hexactinellida), the complex filigreed body is stabilized by an inorganic skeleton composed of amorphous silica providing them a distinct body shape and plan. It is proposed that the key innovation that allowed the earliest metazoans to form larger specimens was the enzyme silicatein. This enzyme is crucial for the formation of the siliceous skeleton. The first sponge fossils with body preservation were dated back prior to the "Precambrian-Cambrian" boundary [Vendian (610-545 Ma)/Ediacaran (542-580 Ma)]. A further molecule required for the formation of a hard skeleton was collagen, fibrous organic filaments that need oxygen for their formation. Silicatein forming the spicules and collagen shaping their morphology are the two organic components that control the appositional growth of these skeletal elements. This process starts in both demosponges and hexactinellids intracellularly and is completed extracellularly where the spicules may reach sizes of up to 3 m. While the basic strategy of their formation is identical in both sponge classes, it differs on a substructural level. In Hexactinellida, the initial silica layers remain separated, those layers bio-fuse (bio-sinter) together in demosponges. In some sponge taxa, e.g., the freshwater sponges from the Lake Baikal, the individual spicules are embedded in an organic matrix that is composed of the DUF protein. This protein comprises clustered stretches of amino acid sequences composed of pronounced hydrophobic segments, each spanning around 35 aa. We concluded with the remark of Thompson (1942) highlighting that "the sponge-spicule is a typical illustration of the theory of 'bio-crystallisation' to form 'biocrystals' ein Mittelding between an inorganic crystal and an organic secretion." Moreover, the understanding of the enzymatic formation of the spicules conferred sponge biosilica a considerable economical actuality as a prime raw material of this millennium.

The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction.

The timing and nature of biotic recovery from the devastating end-Permian mass extinction (252 Ma) are much debated. New studies in South China suggest that complex marine ecosystems did not become re-established until the middle-late Anisian (Middle Triassic), much later than had been proposed by some. The recently discovered exceptionally preserved Luoping biota from the Anisian Stage of the Middle Triassic, Yunnan Province and southwest China shows this final stage of community assembly on the continental shelf. The fossil assemblage is a mixture of marine animals, including abundant lightly sclerotized arthropods, associated with fishes, marine reptiles, bivalves, gastropods, belemnoids, ammonoids, echinoderms, brachiopods, conodonts and foraminifers, as well as plants and rare arthropods from nearby land. In some ways, the Luoping biota rebuilt the framework of the pre-extinction latest Permian marine ecosystem, but it differed too in profound ways. New trophic levels were introduced, most notably among top predators in the form of the diverse marine reptiles that had no evident analogues in the Late Permian. The Luoping biota is one of the most diverse Triassic marine fossil Lagerstätten in the world, providing a new and early window on recovery and radiation of Triassic marine ecosystems some 10 Myr after the end-Permian mass extinction.

Expression of inducible Bcl-X(S) in myeloid leukemia: compensatory upregulation of Bcl-X(L) and Bcl-2 prevents apoptosis and chemosensitization.

Programmed cell death and survival are controlled by complex pathways, with the anti-apoptotic proteins Bcl-2 and Bcl-X(L) and the pro-apoptotic proteins Bax and Bcl-X(S) being major regulators. Variations in the expression of Bcl-X(S) have been observed in leukemic cells from acute myeloid leukemia (AML) patients and correlated with clinical outcome, but the impact of Bcl-X(S) on molecular pathophysiological mechanisms and the potential role of Bcl-X(S) as a therapeutic target in AML are not yet defined. In order to analyze the functional relevance of Bcl-X(S) in AML, Bcl-X(S) was moderately (2-3 fold) overexpressed in the AML cell lines HL-60 and MO7e by transfection with a tetracycline-regulatable Bcl-X(S) expression system. Increased Bcl-X(S) did not change the rate of spontaneous apoptosis, chemosensitivity to ara-C, or cell cycle kinetics. Further analysis of this unexpected result revealed a compensatory transcriptional upregulation of endogenous anti-apoptotic Bcl-X(L) in MO7e and HL-60, and Bcl-2 in HL-60 cells resulting in increased protein levels. Bax levels were unchanged. Bcl-X(L) and Bcl-2 were found to heterodimerize with Bcl-X(S), thereby providing a possible explanation for the abrogation of its pro-apoptotic function. These results suggest the existence of a regulatory mechanism aimed to protect leukemic cells from pro-apoptotic stimuli.

Mechanisms for lysophosphatidic acid-induced cytokine production in ovarian cancer cells.

A potential role for lysophosphatidic acid (LPA) in human oncogenesis was first suggested by the observation that LPA is present at elevated levels in ascites of ovarian cancer patients. In the current study, we demonstrated that LPA is a potent inducer of interleukin-6 (IL-6) and interleukin-8 (IL-8) production in ovarian cancer cells. Both IL-6 and IL-8 have been implicated in ovarian cancer progression. We characterized the IL-8 gene promoter to ascertain the transcriptional mechanism underlying LPA -induced expression of these cytokines. LPA stimulated the transcriptional activity of the IL-8 gene with little effect on IL-8 mRNA stability. The optimal response of the IL-8 gene promoter to LPA relied on binding sites for NF-kappaB and AP-1, two transcription factors that were strongly activated by LPA in ovarian cancer cell lines. Positive regulators of the NF-kappaB and AP-1 pathways synergistically activated the IL-8 gene promoter. Further, the effect of LPA on IL-6 and IL-8 generation is mediated by the Edg LPA receptors as enforced expression of LPA receptors restored LPA-induced IL-6 and IL-8 production in non-responsive cells and enhanced the sensitivity to LPA in responsive cell lines. The LPA(2) receptor was identified to be the most efficient in linking LPA to IL-6 and IL-8 production although LPA(1) and LPA(3) were also capable of increasing the response to a certain degree. These studies elucidate the transcriptional mechanism and the Edg LPA receptors involved in LPA-induced IL-6 and IL-8 production and suggest potential strategies to restrain the expression of these cytokines in ovarian cancer.