18 research outputs found
The Impact of Global Warming and Anoxia on Marine Benthic Community Dynamics: an Example from the Toarcian (Early Jurassic)
The Pliensbachian-Toarcian (Early Jurassic) fossil record is an archive of natural data of benthic community response to global warming and marine long-term hypoxia and anoxia. In the early Toarcian mean temperatures increased by the same order of magnitude as that predicted for the near future; laminated, organic-rich, black shales were deposited in many shallow water epicontinental basins; and a biotic crisis occurred in the marine realm, with the extinction of approximately 5% of families and 26% of genera. High-resolution quantitative abundance data of benthic invertebrates were collected from the Cleveland Basin (North Yorkshire, UK), and analysed with multivariate statistical methods to detect how the fauna responded to environmental changes during the early Toarcian. Twelve biofacies were identified. Their changes through time closely resemble the pattern of faunal degradation and recovery observed in modern habitats affected by anoxia. All four successional stages of community structure recorded in modern studies are recognised in the fossil data (i.e. Stage III: climax; II: transitional; I: pioneer; 0: highly disturbed). Two main faunal turnover events occurred: (i) at the onset of anoxia, with the extinction of most benthic species and the survival of a few adapted to thrive in low-oxygen conditions (Stages I to 0) and (ii) in the recovery, when newly evolved species colonized the re-oxygenated soft sediments and the path of recovery did not retrace of pattern of ecological degradation (Stages I to II). The ordination of samples coupled with sedimentological and palaeotemperature proxy data indicate that the onset of anoxia and the extinction horizon coincide with both a rise in temperature and sea level. Our study of how faunal associations co-vary with long and short term sea level and temperature changes has implications for predicting the long-term effects of “dead zones” in modern oceans
Circadian rhythm of tryptophan in normal volunteers
The daily changes of plasma free and total tryptophan were studied in 15 healthy volunteers. Six blood samples were taken for each subject. A method involving pH control was used. The results show that plasma free tryptophan concentrations progressively rise to reach a peak at 3.30 hr. The total tryptophan concentration reaches a peak at midnight
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Quantifying the dark data in museum fossil collections as palaeontology undergoes a second digital revolution
Large-scale analysis of the fossil record requires aggregation of palaeontological data from individual fossil localities. Prior to computers, these synoptic datasets were compiled by hand, a laborious undertaking that took years of effort and forced palaeontologists to make difficult choices about what types of data to tabulate. The advent of desktop computers ushered in palaeontology's first digital revolution-online literature-based databases, such as the Paleobiology Database (PBDB). However, the published literature represents only a small proportion of the palaeontological data housed in museum collections. Although this issue has long been appreciated, the magnitude, and thus potential significance, of these so-called 'dark data' has been difficult to determine. Here, in the early phases of a second digital revolution in palaeontology--the digitization of museum collections-we provide an estimate of the magnitude of palaeontology's dark data. Digitization of our nine institutions' holdings of Cenozoic marine invertebrate collections from California, Oregon and Washington in the USA reveals that they represent 23 times the number of unique localities than are currently available in the PBDB. These data, and the vast quantity of similarly untapped dark data in other museum collections, will, when digitally mobilized, enhance palaeontologists' ability to make inferences about the patterns and processes of past evolutionary and ecological changes
Phanerozoic trends in the global diversity of marine invertebrates
It has previously been thought that there was a steep Cretaceous and Cenozoic radiation of marine invertebrates. This pattern can be replicated with a new data set of fossil occurrences representing 3.5 million specimens, but only when older analytical protocols are used. Moreover, analyses that employ sampling standardization and more robust counting methods show a modest rise in diversity with no clear trend after the mid-Cretaceous. Globally, locally, and at both high and low latitudes, diversity was less than twice as high in the Neogene as in the mid-Paleozoic. The ratio of global to local richness has changed little, and a latitudinal diversity gradient was present in the early Paleozoic
Techniques for Host Plant Inoculation with Truffles and Other Edible Ectomycorrhizal MushroomsEdible Ectomycorrhizal Mushrooms
Large-scale production of high-quality mycorrhizal plants in the greenhouse is mainstay for the modern cultivation of edible ectomycorrhizal mushrooms (EEMMs). Success at this step not only depends on the reliability of the fungal inoculum used for plantlet mycorrhization but also on the environmental conditions attending symbiosis establishment. Methods developed 40-50 years ago for inoculating host plants with EEMMs are still largely used today, with slight modifications. Mycelial inoculations are used commercially only for some edible ectomycorrhizal (EEM) basidiomycetes, while inoculation with spores is the most common method for producing seedlings colonized with truffle mycorrhizas. However pure cultures and ectomycorrhizas of Tuber have also been used to obtain mycorrhizal plants mainly for scientific purposes. Mycelium-based inoculum offers many advantages, such as lower contamination risks, more reliable root colonization, and provides opportunities for genetic selection of EEMM strains. Long time preservation of EEM cultures and the creation of germplasm banks would be an important step to support mycelium-based technologies. To this aim, we demonstrate successful crypreservation of strains of Tuber borchii and Tuber aestivum. Recent advances in genetic and biotechnology of EEMs and their hosts has the potential to transform the current EEMM nursery trade