University of Portsmouth

About: University of Portsmouth is a education organization based out in Portsmouth, Portsmouth, United Kingdom. It is known for research contribution in the topics: Population & Galaxy. The organization has 5452 authors who have published 14256 publications receiving 424346 citations. The organization is also known as: Portsmouth and Gosport School of Science and Art & Portsmouth and Gosport School of Science and the Arts.

Bulk effects in the cosmological dynamics of brane-world scenarios

Abstract: In this paper we deal with the cosmological dynamics of Randall-Sundrum brane-world type scenarios in which the five-dimensional Weyl tensor has a nonvanishing projection onto the three-brane, where matter fields are confined. Using dynamical systems techniques, we study how the state space of Friedmann-Lema\^{\i}tre-Robertson-Walker and Bianchi type I cosmological models is affected by the bulk Weyl tensor, focusing on the differences that appear with respect to general relativity and also Randall-Sundrum cosmological scenarios without the Weyl tensor contribution.

New ophthalmosaurid ichthyosaurs from the European Lower Cretaceous demonstrate extensive ichthyosaur survival across the Jurassic-Cretaceous boundary.

Abstract: Background Ichthyosauria is a diverse clade of marine amniotes that spanned most of the Mesozoic. Until recently, most authors interpreted the fossil record as showing that three major extinction events affected this group during its history: one during the latest Triassic, one at the Jurassic–Cretaceous boundary (JCB), and one (resulting in total extinction) at the Cenomanian-Turonian boundary. The JCB was believed to eradicate most of the peculiar morphotypes found in the Late Jurassic, in favor of apparently less specialized forms in the Cretaceous. However, the record of ichthyosaurs from the Berriasian–Barremian interval is extremely limited, and the effects of the end-Jurassic extinction event on ichthyosaurs remains poorly understood. Methodology/Principal Findings Based on new material from the Hauterivian of England and Germany and on abundant material from the Cambridge Greensand Formation, we name a new ophthalmosaurid, Acamptonectes densus gen. et sp. nov. This taxon shares numerous features with Ophthalmosaurus, a genus now restricted to the Callovian–Berriasian interval. Our phylogenetic analysis indicates that Ophthalmosauridae diverged early in its history into two markedly distinct clades, Ophthalmosaurinae and Platypterygiinae, both of which cross the JCB and persist to the late Albian at least. To evaluate the effect of the JCB extinction event on ichthyosaurs, we calculated cladogenesis, extinction, and survival rates for each stage of the Oxfordian–Barremian interval, under different scenarios. The extinction rate during the JCB never surpasses the background extinction rate for the Oxfordian–Barremian interval and the JCB records one of the highest survival rates of the interval. Conclusions/Significance There is currently no evidence that ichthyosaurs were affected by the JCB extinction event, in contrast to many other marine groups. Ophthalmosaurid ichthyosaurs remained diverse from their rapid radiation in the Middle Jurassic to their total extinction at the beginning of the Late Cretaceous.

Permanent Genetic Resources added to Molecular Ecology Resources Database 1 August 2009–30 September 2009

Abstract: This article documents the addition of 238 microsatellite marker loci and 72 pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Adelges tsugae, Artemisia tridentata, Astroides calycularis, Azorella selago, Botryllus schlosseri, Botrylloides violaceus, Cardiocrinum cordatum var. glehnii, Campylopterus curvipennis, Colocasia esculenta, Cynomys ludovicianus, Cynomys leucurus, Cynomys gunnisoni, Epinephelus coioides, Eunicella singularis, Gammarus pulex, Homoeosoma nebulella, Hyla squirella, Lateolabrax japonicus, Mastomys erythroleucus, Pararge aegeria, Pardosa sierra, Phoenicopterus ruber ruber and Silene latifolia. These loci were cross-tested on the following species: Adelges abietis, Adelges cooleyi, Adelges piceae, Pineus pini, Pineus strobi, Tubastrea micrantha, three other Tubastrea species, Botrylloides fuscus, Botrylloides simodensis, Campylopterus hemileucurus, Campylopterus rufus, Campylopterus largipennis, Campylopterus villaviscensio, Phaethornis longuemareus, Florisuga mellivora, Lampornis amethystinus, Amazilia cyanocephala, Archilochus colubris, Epinephelus lanceolatus, Epinephelus fuscoguttatus, Symbiodinium temperate-A clade, Gammarus fossarum, Gammarus roeselii, Dikerogammarus villosus and Limnomysis benedeni. This article also documents the addition of 72 sequencing primer pairs and 52 allele specific primers for Neophocaena phocaenoides.

Negative control of Xenopus GATA-2 by activin and noggin with eventual expression in precursors of the ventral blood islands.

Abstract: To increase our understanding of haematopoiesis during early vertebrate development, we have studied the expression pattern of the transcription factor GATA-2 in Xenopus embryos, and asked how this is regulated. We show that the blood island precursors of the ventral mesoderm express GATA-2 RNA at neural tube stages, some 5 hours before globin RNA is detected in their derivatives. Prior to this however, GATA-2 is expressed much more widely within the embryo. Maternal transcripts are uniformly distributed, and zygotic transcription is activated during gastrulation throughout ventral and lateral regions of the embryo, with expression highest in the sensorial ectoderm and only weak in the ventral mesoderm. The domain of GATA-2 expression in neurulae outlines the region of the neural plate and suggests a possible wider role in dorsoventral patterning. To identify the signals involved in regulating this pattern of expression, we performed experiments with embryo explants. GATA-2 is activated autonomously in isolated animal caps and this activation is suppressed by the mesoderm-inducing factor activin, but not by FGF. Thus, the down-regulation of GATA-2 observed in the region of the Spemann organiser may be a response to an activin-like signal emanating from the dorsal-vegetal region or Nieuwkoop centre. GATA-2 activation in animal caps and ventral marginal zones was suppressed by co-culturing with dorsal marginal zones, suggesting that a signal from the Spemann organiser is involved in suppression of GATA-2 in the dorsal region of the embryo. Expression of a candidate for this signal, noggin, had the same effect. Taken together, the observations presented here suggest that GATA-2 activation occurs by default in the absence of signals, that the restriction of its expression within the early embryo is controlled by negative signals emanating from the Nieuwkoop centre and the organiser, and that noggin and activin-like molecules play a role in these signalling pathways.

Why should women have lower reference limits for haemoglobin and ferritin concentrations than men

Abstract: The need to transport oxygen and remove carbon dioxide from animal tissue is a fundamental requirement of life, independent of age or sex.1 The role of iron in humans and many other mammals is central to this process. 2 3 Haemoglobin concentration and red blood cell count are important diagnostic indicators for anaemia in humans and animals. In prepubertal humans no major differences can be found between the sexes in red blood cell count or haemoglobin and serum ferritin concentrations.4 Only after the onset of menstruation does a difference emerge.4 Not until 10 years after the menopause does this situation revert in women, when the haemoglobin concentration becomes similar to that of aged matched men. 4 5 This situation is compounded by the fact that modern women have a different reproductive history from those in the past. They reach sexual maturity at an earlier age, have fewer pregnancies, and breast feed for shorter periods; as such they menstruate for more years than women in the past. Menstruation is the principal cause of iron loss in women.6–8 Furthermore, 90% of UK females of childbearing age do not achieve the recommended daily intake of elemental iron (14.8 mg) from their diet.9 Evaluation of the haemoglobin concentration and red blood cell count of women from Canada, Central America, China, and the United States shows that this situation is widespread. 4 10–14 Women worldwide are at risk of being in a negative iron balance, and by current criteria if their haemoglobin concentration is less than 115 g/l they are deemed to be anaemic, whereas in men the cut-off point is 130 g/l.15 As far as the authors are aware, of the primates only humans show a sex difference in haemoglobin concentration and red blood …