Optically Stimulated Luminescence Dating Supports Central Arctic Ocean CM-scale Sedimentation Rates

This paper presents new results from Optically Stimulated Luminescence (OSL) dating on a sediment core raised from the crest of the Lomonosov Ridge in the central Arctic Ocean. There has been much debate about dating sediment cores from the central Arctic Ocean and by using an independent absolute dating technique we aim to test whether or not relatively fast, cm-scale/ka, sedimentation rates were typical of Arctic’s Pleistocene depositional mode. On the basis of mainly paleomagnetic reversal stratigraphy, many previous studies suggest mm-scale/ka sedimentation rates. A common feature in these studies is that the first down core paleomagnetic negative inclination is consistently interpreted as the Brunhes/Matuyama boundary at about 780 ka. Our OSL dating results indicate that this assumption is not generally valid, and that the first encountered negative inclination represents younger age excursions within the Brunhes Chron, implying reinterpretation of many published core studies where paleoenvironmental reconstructions have been made for the central Arctic Ocean. Our dating results furthermore corroborates a correlation of the uppermost 2–3 m of the Lomonosov Ridge cores to a well-dated core located off the Barents-Kara Sea margin that in turn is correlated to cores in the Fram Strait. Valuable information on the paleoceanographical evolution in the Arctic Ocean from MIS 6 to the Holocene is given through this correlation of records from the central Arctic Ocean to records off the Eurasian continental margin

Sophisticated sperm allocation in male fowl

When a female is sexually promiscuous, the ejaculates of different males compete for the fertilization of her eggs; the more sperm a male inseminates into a female, the more likely he is to fertilize her eggs. Because sperm production is limited and costly, theory predicts that males will strategically allocate sperm (1) according to female promiscuity, (2) saving some for copulations with new females, and (3) to females producing more and/or better offspring. Whether males allocate sperm in all of these ways is not known, particularly in birds where the collection of natural ejaculates only recently became possible. Here we demonstrate male sperm allocation of unprecedented sophistication in the fowl Gallus gallus. Males show status-dependent sperm investment in females according to the level of female promiscuity; they progressively reduce sperm investment in a particular female but, on encountering a new female, instantaneously increase their sperm investment; and they preferentially allocate sperm to females with large sexual ornaments signalling superior maternal investment. Our results indicate that female promiscuity leads to the evolution of sophisticated male sexual behaviour

Sophisticated sperm allocation in male fowl

When a female is sexually promiscuous, the ejaculates of different males compete for the fertilization of her eggs; the more sperm a male inseminates into a female, the more likely he is to fertilize her eggs. Because sperm production is limited and costly, theory predicts that males will strategically allocate sperm (1) according to female promiscuity, (2) saving some for copulations with new females, and (3) to females producing more and/or better offspring. Whether males allocate sperm in all of these ways is not known, particularly in birds where the collection of natural ejaculates only recently became possible. Here we demonstrate male sperm allocation of unprecedented sophistication in the fowl Gallus gallus. Males show status-dependent sperm investment in females according to the level of female promiscuity; they progressively reduce sperm investment in a particular female but, on encountering a new female, instantaneously increase their sperm investment; and they preferentially allocate sperm to females with large sexual ornaments signalling superior maternal investment. Our results indicate that female promiscuity leads to the evolution of sophisticated male sexual behaviour

Paleomagnetic Chronology of Arctic Ocean Sediment Cores: Reversals and Excursions -The Conundrum

Chronologies of Arctic Ocean sediment cores are mainly based on interpretation of paleomagnetic inclination records. The first paleomagnetic chronology assigned zones with negative inclinations to polarity reversals (Steuerwald et al, 1968) because geomagnetic excursions at that time were a novel observation and had only been reported from lavas. Arctic Ocean sedimentation rates were thus established to be in the mm/ka-range. A general recognition of excursions as real features of the geomagnetic field emerged more than three decades later, and presently there is still no consensus regarding the number (or name), duration and age of global synchronous excursions within the Brunhes Chron. Assigning inclination records to polarity reversals or excursions is an ambiguous exercise without independent age information. Based on independently derived time frames, 11 negative inclination intervals in core 96/12-1pc from the Lomonosov Ridge were assigned to reported excursions resulting in cm/ka deposition rates (Jakobsson et al, 2000). However, the detail of the excursional stratigraphy in this core is problematic. The absence of two (three?) excursions in the upper 2 m of core (base MIS5) was tentatively suggested to reflect pDRM-erasing in this sandy part of the core, while the short extent of the inferred pre-Brunhes Matyuama Chron remains unaccounted for. We have recently retrieved a relative paleointensity record from a parallel core (96/B6-1pc) for alternative dating control and assessment of stratigraphic completeness and uniformity of deposition. This study indicated the presence of a hiatus of the order of 200 ka (Løvlie et al 2002). We present a paleointensity record from core 96/12-1pc and will address identification of depositional hiatuses and their significance in understanding the paleomagnetic record in Arctic Ocean core

Rates of Sedimentation in the Central Arctic Ocean

The Arctic Ocean is presently undergoing geoscientific investigations of the type that occurred during the late 1940\u27s through 1960\u27s in the Atlantic, Indian and Pacific oceans. Seismic reflection and refraction data are scarce in the Arctic Ocean and large areas are virtually unsampled with respect to piston or gravity coring. The vast majority of available cores are less than10 m in length and largely lack biostratigraphically useful calcareous and siliceous microfossils. No drill cores exist from the ridges or deep basins in the central Arctic Ocean. Considering the limited geophysical and geological data available, it is not surprising that current concepts about Arctic Ocean sedimentation rates are diverging. The main point of difference is whether or not strongly subdued rates of sedimentation persisted in the central Arctic Ocean during Plio-Pleistocene times. The low sedimentation rate scenario is based on age models suggesting Plio-Pleistocene rates that vary between about 0.04 and 0.4 cm/ka. This scenario is chiefly derived from cores raised from ridges in the Amerasian Basin and implies that the majority of cores presently available extend well into, or encompass the entire, Pliocene. The contrasting high sedimentation rate scenario is based on age models suggesting rates that vary from about one to a few cm/ka, derived from cores from ridges and basins in both the Amerasian and Eurasian parts of the central Arctic Ocean. The latter scenario implies that most short cores rarely extend beyond the Pleistocene. Early paleomagnetic chronologies of sediment cores retrieved from the Amerasian Basin were based on the assumption that zones with negative inclination represented genuine polarity reversals. The first encountered down-core zone with negative inclination was interpreted to be the Brunhes/Matuyama boundary. This approach yielded mm-scale Plio-Pleistocene sedimentation rates. Biostratigraphy, cyclostratigraphy, and OSL dating, subsequently have indicated that many of these negative inclination changes represent Brunhes geomagnetic excursions, thus providing cm-scale Pleistocene sedimentation rates. All longer-term, Cretaceouos through Cenozoic, sedimentation rates derived from seismic reflection and tectonic models of bedrock age are on the order of cm/ka

Evolutionary associations between host traits and parasite load: insights from Lake Tanganyika cichlids

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Parasite diversity and abundance (parasite load) vary greatly among host species. However, the influence of host traits on variation in parasitism remains poorly understood. Comparative studies of parasite load have largely examined measures of parasite species richness, and are predominantly based on records obtained from published data. Consequently, little is known about the relationships between host traits and other aspects of parasite load, such as parasite abundance, prevalence, and aggregation. Meanwhile, understanding of parasite species richness may be clouded by limitations associated with data collation from multiple independent sources. We conducted a field study of Lake Tanganyika cichlid fishes and their helminth parasites. Using a Bayesian phylogenetic comparative framework, we tested evolutionary associations between five key host traits (body size, gut length, diet breadth, habitat complexity, number of sympatric hosts) predicted to influence parasitism, together with multiple measures of parasite load. We find that the number of host species that a particular host may encounter due to its habitat preferences emerges as a factor of general importance for parasite diversity, abundance, and prevalence, but not parasite aggregation. In contrast, body size and gut size are positively related to aspects of parasite load within, but not between species. The influence of host phylogeny varies considerably among measures of parasite load, with the greatest influence exerted on parasite diversity. These results reveal that both host morphology and biotic interactions are key determinants of host-parasite associations, and that consideration of multiple aspects of parasite load is required to fully understand patterns in parasitism

Current evidence for a modulation of low back pain by human genetic variants

The manifestation of chronic back pain depends on structural, psychosocial, occupational and genetic influences. Heritability estimates for back pain range from 30% to 45%. Genetic influences are caused by genes affecting intervertebral disc degeneration or the immune response and genes involved in pain perception, signalling and psychological processing. This inter-individual variability which is partly due to genetic differences would require an individualized pain management to prevent the transition from acute to chronic back pain or improve the outcome. The genetic profile may help to define patients at high risk for chronic pain. We summarize genetic factors that (i) impact on intervertebral disc stability, namely Collagen IX, COL9A3, COL11A1, COL11A2, COL1A1, aggrecan (AGAN), cartilage intermediate layer protein, vitamin D receptor, metalloproteinsase-3 (MMP3), MMP9, and thrombospondin-2, (ii) modify inflammation, namely interleukin-1 (IL-1) locus genes and IL-6 and (iii) and pain signalling namely guanine triphosphate (GTP) cyclohydrolase 1, catechol-O-methyltransferase, μ opioid receptor (OPMR1), melanocortin 1 receptor (MC1R), transient receptor potential channel A1 and fatty acid amide hydrolase and analgesic drug metabolism (cytochrome P450 [CYP]2D6, CYP2C9)

Определение БАПНА-амидазной активности иммуноглобулинов у больных кишечными инфекциями

АМИДОГИДРОЛАЗЫИММУНОГЛОБУЛИНЫАНТИТЕЛАКИШЕЧНЫЕ БОЛЕЗНИАНТИТЕЛА КАТАЛИТИЧЕСКИЕИНФЕКЦИЯБАПНА-АМИДАЗНАЯ АКТИВНОСТ