Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Bay

  • Jervi bay
  • baffin bay
  • chesapeake bay
  • delaware bay
  • florida bay
  • francisco bay
  • hudson bay
  • iskenderun bay
  • monterey bay
  • san francisco bay
  • shark bay

  • Terms modified by Bay

  • bay area
  • bay formation
  • bay k
  • bay region

  • Selected Abstracts

    Activation of CysLT receptors induces astrocyte proliferation and death after oxygen,glucose deprivation

    GLIA, Issue 1 2008
    Xiao-Jia Huang
    Abstract We recently found that 5-lipoxygenase (5-LOX) is activated to produce cysteinyl leukotrienes (CysLTs), and CysLTs may cause neuronal injury and astrocytosis through activation of CysLT1 and CysLT2 receptors in the brain after focal cerebral ischemia. However, the property of astrocyte responses to in vitro ischemic injury is not clear; whether 5-LOX, CysLTs, and their receptors are also involved in the responses of ischemic astrocytes remains unknown. In the present study, we performed oxygen-glucose deprivation (OGD) followed by recovery to induce ischemic-like injury in the cultured rat astrocytes. We found that 1-h OGD did not injure astrocytes (sub-lethal OGD) but induced astrocyte proliferation 48 and 72 h after recovery; whereas 4-h OGD moderately injured the cells (moderate OGD) and led to death 24,72 h after recovery. Inhibition of phospholipase A2 and 5-LOX attenuated both the proliferation and death. Sub-lethal and moderate OGD enhanced the production of CysLTs that was inhibited by 5-LOX inhibitors. Sub-lethal OGD increased the expressions of CysLT1 receptor mRNA and protein, while moderate OGD induced the expression of CysLT2 receptor mRNA. Exogenously applied leukotriene D4 (LTD4) induced astrocyte proliferation at 1,10 nM and astrocyte death at 100,1,000 nM. The CysLT1 receptor antagonist montelukast attenuated astrocyte proliferation, the CysLT2 receptor antagonist BAY cysLT2 reversed astrocyte death, and the dual CysLT receptor antagonist BAY u9773 exhibited both effects. In addition, LTD4 (100 nM) increased the expression of CysLT2 receptor mRNA. Thus, in vitro ischemia activates astrocyte 5-LOX to produce CysLTs, and CysLTs result in CysLT1 receptor-mediated proliferation and CysLT2 receptor-mediated death. © 2007 Wiley-Liss, Inc. [source]

    Labelling of the guanylate cyclase activator cinaciguat (BAY 58-2667) with carbon-14, tritium and stable isotopes

    D. Seidel
    Abstract For studies of pharmacokinetics and drug metabolism of the new soluble guanylate cyclase activator cinaciguat (BAY 58-2667) the 14C-labelled compound was synthesized. The tritiated compound was required to elucidate the mode of action and the stable labelled compound was required for bio-analytical studies by quantitative mass spectrometry as well. Two radiosyntheses are described with different formation of the labelled intermediate 1-(chloro[14C]methyl)-4-(2-phenylethyl)benzene. The first one started with 14C-carboxylation of 1-bromo-4-(2-phenylethyl)benzene yielding the desired product in 5 steps. In the second synthesis intermediate 1-(chloro[14C]methyl)-4-(2-phenylethyl)benzene was formed by chloromethylation of bibenzyl with [14C]paraformaldehyde/hydrochloric acid subsequently resulting in the final product in three steps. Tritium labelling was performed by tritium exchange of the diester intermediate using an organo-iridium catalyst and subsequent saponification. The stable labelled compound was synthesized via a convergent synthesis starting with 13C,15N-cyanation of 1-(chloromethyl)-2-{[4-(2-phenylethyl)benzyl]oxy}benzene and 13C-cyanation of methyl 4-bromobenzoate, respectively. The labelled product was obtained after 7 chemical steps. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    Syntheses of [14C]BAY 59-7939 and its radiolabeled metabolite M-4

    U. Pleiss
    Abstract BAY 59-7939 is a novel, oral, direct Factor Xa inhibitor in clinical development for the prevention and treatment of thromboembolic diseases. Radiolabeled BAY 59-7939 was required for drug absorption, distribution, metabolism and excretion (ADME studies). The BAY 59-7939 was labeled with carbon-14 in the carboxamide group in one step in an overall radiochemical yield of 85% starting from 4-{4-[(5S)-5-(aminomethyl)-2-oxo-1,3-oxazolidin-3-yl]phenyl}mor-pholin-3-one and 5-chlorothiophene-2-[14C]carboxylic acid. The radiolabeled metabolite M-4 was prepared in 77% yield starting from [1- 14C]glycine and 5-chlorothiophene-5-carboxylic acid. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Syntheses of [2H3, 15N], [14C]NexavarÔ and its labeled metabolites

    U. Pleiss
    Abstract NexavarÔ, Sorafenib tosylate (BAY 43-9006 tosylate) is a potent small molecule Raf kinase inhibitor for the treatment of hyperproliferative disorders such as cancer. Both radiolabeled and stable isotope labeled compounds were required for drug absorption, distribution, metabolism and excretion (ADME) and quantitative mass spectrometry bio-analytical studies. NexavarÔ labeled with carbon-14 in the carboxamide group was prepared in two steps in an overall radiochemical yield of 42% starting from 4-chloro- N -methyl-2-pyridine-[14C]carboxamide. The [2H3,15N] version of NexavarÔ was prepared in 75% yield based on 4-chloro- N -[2H3]methyl-2-pyridine-[15N]carboxamide. The pyridine N -oxide metabolite labeled with carbon-14 as well as with deuterium and nitrogen-15 and was synthesized by oxidation in yields of 59% and 87%, respectively. Starting from [2H2, 13C]formaldehyde the N -hydroxymethyl metabolite was labeled with carbon-13 and deuterium in one step in a 45% overall yield. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    Tumor necrosis factor-alpha (TNF-,) regulates Toll-like receptor 2 (TLR2) expression in microglia

    Mohsin Md.
    Abstract Microglia represent one effector arm of CNS innate immunity as evident by their role in pathogen recognition. We previously reported that exposure of microglia to Staphylococcus aureus (S. aureus), a prevalent CNS pathogen, led to elevated Toll-like receptor 2 (TLR2) expression, a pattern recognition receptor capable of recognizing conserved structural motifs associated with gram-positive bacteria such as S. aureus. In this study, we demonstrate that the proinflammatory cytokine tumor necrosis factor-, (TNF-,) enhances TLR2 expression in microglia, whereas interleukin-1, has no significant effect. To determine the downstream signaling events responsible for elevated microglial TLR2 expression in response to TNF-,, a series of signal transduction inhibitors were employed. Treatment with caffeic acid phenethyl ester, an inhibitor of redox-mediated nuclear factor-kappa B activation, significantly attenuated TNF-,-induced TLR2 expression. Similar results were observed with the IKK-2 and I,B-, inhibitors SC-514 and BAY 11-7082, respectively. In contrast, no significant alterations in TLR2 expression were observed with protein kinase C or p38 mitogen-activated protein kinase inhibitors. A definitive role for TNF-, was demonstrated by the inability of S. aureus to augment TLR2 expression in microglia isolated from TNF-, knockout mice. In addition, TLR2 expression was significantly attenuated in brain abscesses of TNF-, knockout mice. Collectively, these results indicate that in response to S. aureus, TNF-, acts in an autocrine/paracrine manner to enhance TLR2 expression in microglia and that this effect is mediated, in part, by activation of the nuclear factor-kappa B pathway. [source]

    Glioma cells under hypoxic conditions block the brain microvascular endothelial cell death induced by serum starvation

    Yoshifumi Ueda
    Abstract Angiogenesis is one of essential components for the growth of neoplasms, including malignant gliomas. However, tumor vascularization is often poorly organized and marginally functional due to tumor strucutural abnormalities, inducing regional or temporal hypoxic conditions and nutritional shortages in tumor tissues. We investigated how during angiogenesis migrating endothelial cells survive in these hypoxic and reduced nutritional conditions. Human brain microvascular endothelial cells (HBMECs) underwent apoptosis and necrosis after serum withdrawal. This endothelial cell death was blocked by recombinant VEGF protein or the culture medium of U251 glioma cells exposed to hypoxia (H-CM). Hypoxic treatment increased vascular endothelial growth factor (VEGF) and tumor necrosis factor alpha (TNF-,) expression in U251 glioma cells. H-CM activated nuclear factor-,B (NF,B) protein and increased the gene expression of antiapoptotic factors including Bcl-2, Bcl-XL, survivin and X-chromosome-linked inhibitor of apoptosis protein (XIAP) in endothelial cells. The survival activity of H-CM for endothelial cells was abolished by two kinds of VEGF inhibitors {Cyclopeptidic VEGF inhibitor and a VEGF receptor tyrosine kinase inhibitor (4-[(4,-chloro-2,-fluoro) phenylamino]-6, 7-dimethoxyquinazoline)} or NF,B inhibitors (ALLN and BAY 11,7082). These VEGF inhibitors did not block the activation of NF,B induced by H-CM in endothelial cells. On the contrary, TNF-, antagonist WP9QY enhanced the survival activity of H-CM for endothelial cells and blocked NF,B activation induced by H-CM under serum-starved conditions. Taken together, our data suggest that both the secretion of VEGF from glioma cells and activation of NF,B in endothelial cells induced by TNF-, are necessary for endothelial cell survival as they increase the expression of antiapoptotic genes in endothelial cells under conditions of serum starvation. These pathways may be one of the mechanisms by which angiogenesis is maintained in glioma tissues. [source]


    JOURNAL OF PHYCOLOGY, Issue 4 2009
    Yoanna Eissler
    Numerous microalgal species are infected by viruses that have the potential to control phytoplankton dynamics by reducing host populations, preventing bloom formation, or causing the collapse of blooms. Here we describe a virus infecting the diatom Chaetoceros cf. wighamii Brightw. from the Chesapeake Bay. To characterize the morphology and lytic cycle of this virus, we conducted a time-course experiment, sampling every 4 h over 72 h following viral inoculation. In vivo fluorescence began to decline 16 h after inoculation and was reduced to <19% of control cultures by the end of experiment. TEM confirmed infection within the first 8 h of inoculation, as indicated by the presence of virus-like particles (VLP) in the nuclei. VLP were present in two different arrangements: rod-like structures that appeared in cross-section as paracrystalline arrays of hexagonal-shaped profiles measuring 12 ± 2 nm in diameter and uniformly electron-dense hexagonal-shaped particles measuring , 22,28 nm in diameter. Nuclei containing paracrystalline arrays were most prevalent early in the infection cycle, while cells containing VLP increased and then declined toward the end of the cycle. The proportion of nuclei containing both paracrystalline arrays and VLP remained relatively constant. This pattern suggests that rod-like paracrystalline arrays fragmented to produce icosahedral VLP. C. cf. wighamii nuclear inclusion virus (CwNIV) is characterized by a high burst size (averaged 26,400 viruses per infected cell) and fast generation time that could have ecological implications on C. cf. wighamii population control. [source]


    J.C. Agan
    Benthic algal sampling from selected sites along Corpus Christi Bay and from one site at the Port Aransas, Texas south jetty was completed between April 1999 and February, 2000. Species composition, seasonal periodicity, and fluctuations in temperature and salinity were determined. This is the first comprehensive study of benthic macroalgae conducted in Corpus Christi Bay, which is shallow, turbid, and lacks natural hard substrate. Man-made jetties are necessary for suitable floral attachment. Macroalgae are affected by changes in salinity as freshwater inflows are followed by periods of drought, which increase salinity. These effects are most notable where freshwater enters at the south end near Oso Bay and at the north end at Nueces Bay. Previous Texas algal collections described species of Enteromorpha, Ulva, Gelidium, and Gracilaria as the most dominant plants of the area. This supports the current study with the additions of Hypnea musciformis and Centroceras clavulatum. Dominant plants at the Port Aransas jetty include Ulva fasciata, Padina gymnospora, and Hypnea musciformis. The Rhodophyta including Gracilaria, Gelidium, and Centroceras clavulatum dominate the bay and do so throughout the year. Chlorophytes, although few in species richness, are important to benthic coverage and biomass. Phaeophyta are found predominantly at the Port Aransas jetty with Sargassum, Dictyota dichotoma, and Petalonia fascia being most abundant. A transition occurs in species composition as the water temperature changes seasonally. Hincksia, Ectocarpus, and Petalonia fascia are found only during the cooler months. [source]


    N.G. Klotchkova
    Most industrial and agricultural enterprises of the Kamchatsky district are situated along the coast of the Avacha Bay and its river drainage. Intensive water pollution resulted in extreme deterioration of the bay's ecology. The destruction of macrophytobenthos under the influence of pollution was investigated. Materials were regularly collected at the same sampling sites in different seasons of the year from 1988 up to 1999. Analysis of our data allowed us to determine directions of long-term changes of species composition and macrophytobenthos structure, speed of degradation of different types of vegetational communities and reasons for all these processes. The Avacha Bay's flora consisted of more than 160 species up to 1970s, including species belonged to 104 genera, 47 families, 23 orders, 3 divisions (30 Chlorophyta, 48 Phaeophyta, 82 Rhodophyta). Flora of the internal part of the bay differed from that of the bay's mouth and consisted of 143 and 146 species, respectively. Presently, the whole flora of the bay (internal part+ throat) includes only 94 species. Along the urban coast 18 poly- and mesosaprobious species are found only. They are characterized by small sizes, low productivity and short life cycles. Most of them are ephemeral with a primitive morphology. The responsive reaction of algae to pollution resulted in decreases in size and weight of the thalli, and appearance of anomalies of development. Laminaria bongardiana was used as a bioindicator. The changes of weight and sizes of its plants allow us to determine degree of the pollution in different parts of the coast of the Avacha Bay. [source]

    Oral, direct Factor Xa inhibition with BAY 59-7939 for the prevention of venous thromboembolism after total hip replacement

    Summary.,Background:,Joint replacement surgery is an appropriate model for dose-ranging studies investigating new anticoagulants. Objectives:,To assess the efficacy and safety of a novel, oral, direct factor Xa (FXa) inhibitor , BAY 59-7939 , relative to enoxaparin in patients undergoing elective total hip replacement. Methods:,In this double-blind, double-dummy, dose-ranging study, patients were randomized to oral BAY 59-7939 (2.5, 5, 10, 20, or 30 mg b.i.d.), starting 6,8 h after surgery, or s.c. enoxaparin 40 mg once daily, starting on the evening before surgery. Treatment was continued until mandatory bilateral venography was performed 5,9 days after surgery. Results:,Of 706 patients treated, 548 were eligible for the primary efficacy analysis. The primary efficacy endpoint was the incidence of any deep vein thrombosis, non-fatal pulmonary embolism, and all-cause mortality; rates were 15%, 14%, 12%, 18%, and 7% for BAY 59-7939 2.5, 5, 10, 20, and 30 mg b.i.d., respectively, compared with 17% for enoxaparin. The primary efficacy analysis did not demonstrate any significant trend in dose,response relationship for BAY 59-7939. The primary safety endpoint was major, postoperative bleeding; there was a significant increase in the frequency of events with increasing doses of BAY 59-7939 (P = 0.045), but no significant differences between individual BAY 59-7939 doses and enoxaparin. Conclusions:,When efficacy and safety were considered together, the oral, direct FXa inhibitor BAY 59-7939, at 2.5,10 mg b.i.d., compared favorably with enoxaparin for the prevention of venous thromboembolism in patients undergoing elective total hip replacement. [source]


    Kara C. Buckstaff
    Abstract Watercraft may provide the greatest source of anthropogenic noise for bottlenose dolphins living in coastal waters. A resident community of about 140 individuals near Sarasota, Florida, are exposed to a vessel passing within 100 m approximately every six minutes during daylight hours. I investigated the circumstances under which watercraft traffic may impact the acoustic behavior of this community, specifically looking for short-term changes in whistle frequency range, duration, and rate of production. To analyze whistles and received watercraft noise levels, acoustic recordings were made using two hydrophones towed from an observation vessel during focal animal follows of 14 individual dolphins. The duration and frequency range of signature whistles did not change significantly relative to vessel approaches. However, dolphins whistled significantly more often at the onset of approaches compared to during and after vessel approaches. Whistle rate was also significantly greater at the onset of a vessel approach than when no vessels were present. Increased whistle repetition as watercraft approach may simply reflect heightened arousal, an increased motivation for animals to come closer together, with whistles functioning to promote reunions. It may also be an effective way to compensate for signal masking, maintaining communication in a noisy environment. [source]


    Michael Krützen
    Abstract We examined population substructure of bottlenose dolphins (Tursiops sp). in Shark Bay, Western Australia, using 10 highly polymorphic microsatellite loci, and mitochondrial DNA (mtDNA). For microsatellite analysis, 302 different animals were sampled from seven localities throughout the bay. Analysis of genetic differentiation between sampling localities showed a significant correlation between the number of migrants (Nm) calculated from FST, RST and private alleles, and distance between localities,a pattern of isolation-by-distance. For mtDNA, 220 individuals from all seven localities were sequenced for a 351 base pair fragment of the control region, resulting in eight haplotypes, with two distinct clusters of haplotypes. Values of FST and (,)ST for mtDNA yielded statistically significant differences, mostly between localities that were not adjacent to each other, suggesting female gene flow over a scale larger than the sampled localities. We also observed a significant correlation between the number of female migrants calculated from FST and ,ST and the distance of sampling localities. Our results indicate that dispersal in female dolphins in Shark Bay is more restricted than that of males. [source]


    Meike Holst
    Abstract In conjunction with the International North Water Polynya Study (NOW) in northern Baffin Bay, we examined the diets of ringed seals (Phoca hispida)1 on the west (Grise Fiord, Nunavut) and east (Qaanaaq, Greenland) sides of the polynya, using conventional stomach content analysis, as well as inferences from stable isotope ratios in seal muscle. Between May and July 1998, stomach and muscle tissue samples were collected from 99 ringed seals taken near Grise Fiord and 100 taken near Qaanaaq. The amphipod Themisto libellula was the dominant prey type in the diet of immature ringed seals from Grise Fiord, whereas arctic cod (Boreogadus saida) and polar cod (Arctogadus glacialis) predominated in the diet of adults. Both immature and adult seals collected near Qaanaaq fed predominantly on arctic cod. Overall, seals collected near Grise Fiord had significantly higher ,13C values than those collected near Qaanaaq (P < 0.001), but there was no statistical separation in ,15N values between the two samples (P= 0.06). Differences in diets of ringed seals from the east and west sides of the North Water Polynya may be due to differences in prey distribution and/or differences in biological productivity and fish biomass within the polynya. [source]

    Real-time Visualization of Photochemically Induced Fluorescence of 8-Halogenated Quinolones: Lomefloxacin, Clinafloxacin and Bay3118 in Live Human HaCaT Keratinocytes,

    Edmond B. Koker
    Halogenoquinolones are potent and widely used antimicrobials blocking microbial DNA synthesis. However, they induce adverse photoresponses through the absorption of UV light, including phototoxicity and photocarcinogenicity. The phototoxic responses may be the result of photosensitization of singlet oxygen, production of free radicals and/or other reactive species resulting from photodehalogenation. Here, we report the use of laser scanning confocal microscopy to detect and to follow the fluorescence changes of one monohalogenated and three di-halogenated quinolones in live human epidermal keratinocyte cells during in situ irradiation by confocal laser in real time. Fluorescence image analysis and co-staining with the LysoTracker probe showed that lysosomes are a preferential site of drug localization and phototransformations. As the lysosomal environment is relatively acidic, we also determined how low pH may affect the dehalogenation and concomitant fluorescence. With continued UV irradiation, fluorescence increased in the photoproducts from BAY y3118 and clinafloxacin, whereas it decreased for lomefloxacin and moxifloxacin. Our images not only help to localize these phototoxic agents in the cell, but also provide means for dynamic monitoring of their phototransformations in the cellular environment. [source]

    High-performance liquid chromatography/tandem mass spectrometry for the quantitative analysis of a novel taxane derivative (BAY59-8862) in biological samples and characterisation of its metabolic profile in rat bile samples

    Cristina Sottani
    A sensitive, specific, accurate and reproducible high-performance liquid chromatography (HPLC) analytical method was developed and validated for the quantification of the novel oral taxane analogue BAY59-8862 in mouse plasma and tissue samples. A fully automated solid-phase extraction procedure was applied to the plasma after internal standard (IS) addition, with only 0.2,mL volume of the sample loaded on a CN-Sep-pak cartridge. In the case of the tissues a very simple acetonitrile extraction was used to recover BAY59-8862 and its internal standard from liver. The procedure for the quantification of BAY59-8862 and its IS (IDN5127) is based on high-performance liquid chromatography/ion spray-tandem mass spectrometry, operating in selected ion monitoring mode. The retention times of BAY and IS were 7.21 and 10.36,min, respectively. In both plasma and tissue specimens the assay was linear in the range 50,5000,ng/mL (ng/g). The overall precision and accuracy were assessed on three different days. The results for plasma were within 6.1% (precision) and between 99 and 112% (accuracy), and for the liver samples within 7.3% and between 104 and 118%, respectively. The LOD was 5,ng/mL and 20,ng/g in the plasma and liver, respectively. In addition, the biliary excretion of the compound in rats was studied. The study showed that an oxidative chemical reaction was the preferred metabolic pathway for biliary excretion, and two sets of mono- and dihydroxylated metabolites were detected by LC/ISP-MS/MS experiments. With this method, BAY59-8862 pharmacokinetic was determined in mice. The combined results demonstrate that the methodology can be considered a valid approach to conduct pharmacokinetic and metabolic studies during preclinical and clinical investigations. Copyright © 2001 John7 Wiley & Sons, Ltd. [source]

    Characterization of Phosphodiesterase Type 5 Expression and Functional Activity in the Human Male Lower Urinary Tract

    Benedetta Fibbi MD
    ABSTRACT Introduction., Phosphodiesterase type 5 (PDE5) inhibitors ameliorate low urinary tract (LUT) symptoms in men with ED and symptomatic benign prostatic hyperplasia (BPH). PDE5 is highly expressed in rat and human bladder, where it regulates cyclic guanosine monophosphate (cGMP) degradation, muscle tone, and proliferation. Aim., To investigate PDE5 tissue distribution and activity in human LUT tissues (urethra, prostate, and bladder). Main Outcome Measures., PDE5 expression and activity were analyzed and compared within the same BPH patient in LUT tissues and in smooth muscle cells (SMCs) cultured from urethra, prostate, and bladder. Methods., In LUT tissues, PDE5 was localized by immunohistochemistry and mRNA expression by quantitative real-time polymerase chain reaction. Proliferation assay was used as readout of PDE5 activity, evaluated as ability of vardenafil to increase the antiproliferative effect of different nitric oxide (NO)/cGMP pathway activators [the PDE5-resistant cGMP analog Sp-8-Br-PET-cGMPS, the NO donor sodium nitroprusside (SNP), and the soluble guanylate cyclase (sGC) stimulator BAY 41-8543]. Results., In all the LUT tissues, PDE5 was immunolocalized in blood vessels and in muscular fibres, but not in epithelium. PDE5 mRNA expression was higher in urethra and bladder than in prostate SMC. The antiproliferative effect of Sp-8-Br-PET-cGMPS was similar in all LUT SMC. In prostatic SMC, SNP and BAY 41-8543 show a dose-dependent antiproliferative effect that resulted marginally enhanced by vardenafil. Conversely, in urethra and bladder SMC the antiproliferative effect of SNP and BAY 41-8543 was lower than in prostatic SMC, but it was significantly enhanced by vardenafil. In urethral and bladder cells vardenafil half-maximal response inhibiting concentration was in the subnanomolar range, whereas in prostate cells it resulted significantly higher. Conclusions., The highest expression and biological activity of PDE5 was found in bladder. However, a consistent PDE5 expression and activity was also found in prostatic urethra. In contrast, the prostate gland showed the lowest PDE5 abundance and cultures derived from this tissue were less sensitive to vardenafil. Fibbi B, Morelli A, Vignozzi L, Filippi S, Chavalmane A, De Vita G, Marini M, Gacci M, Vannelli GB, Sandner P, and Maggi M. Characterization of phosphodiesterase type 5 expression and functional activity in the human male lower urinary tract. J Sex Med 2010;7:59,69. [source]

    Combined targeting of MAPK and AKT signalling pathways is a promising strategy for melanoma treatment

    F. Meier
    Summary Background, In melanoma, several signalling pathways are constitutively activated. Among them, the RAS/RAF/MEK/ERK (MAPK) and PI3K/AKT (AKT) signalling pathways are activated through multiple mechanisms and appear to play a major role in melanoma development and progression. Objectives, In this study, we examined whether targeting the MAPK and/or AKT signalling pathways would have therapeutic effects against melanoma. Methods, Using a panel of pharmacological inhibitors (BAY 43-9006, PD98059, U0126, wortmannin, LY294002) we inhibited the MAPK and AKT signalling pathways at different levels and evaluated the effects on growth, survival and invasion of melanoma cells in monolayer and organotypic skin culture. Results, Antiproliferative and proapoptotic effects of inhibitors alone in monolayer culture were disappointing and varied among the different cell lines. In contrast, combined targeting of the MAPK and AKT signalling pathways significantly inhibited growth and enhanced apoptosis in monolayer culture. To verify our data in a more physiological context we incorporated melanoma cells into regenerated human skin mimicking the microenvironment of human melanoma. Combinations of MAPK and AKT inhibitors completely suppressed invasive tumour growth of melanoma cells in regenerated human skin. Conclusions, Combined targeting of MAPK and AKT signalling pathways is a promising strategy for melanoma treatment and should encourage further in-depth investigations. [source]

    Prostanoid EP1 - and TP-receptors involved in the contraction of human pulmonary veins

    Laurence Walch
    To characterize the prostanoid receptors (TP, FP, EP1 and/or EP3) involved in the vasoconstriction of human pulmonary veins, isolated venous preparations were challenged with different prostanoid-receptor agonists in the absence or presence of selective antagonists. The stable thromboxane A2 mimetic, U46619, was a potent constrictor agonist on human pulmonary veins (pEC50=8.60±0.11 and Emax=4.61±0.46 g; n=15). The affinity values for two selective TP-antagonists (BAY u3405 and GR32191B) versus U46619 were BAY u3405: pA2=8.94±0.23 (n=3) and GR32191B: apparent pKB=8.25±0.34 (n=3), respectively. These results are consistent with the involvement of TP-receptor in the U46619 induced contractions. The two EP1 -/EP3 - agonists (17-phenyl-PGE2 and sulprostone) induced contraction of human pumonary veins (pEC50=8.56±0.18; Emax=0.56±0.24 g; n=5 and pEC50=7.65±0.13; Emax=1.10±0.12 g; n=14, respectively). The potency ranking for these agonists: 17-phenyl-PGE2>sulprostone suggests the involvement of an EP1 -receptor rather than EP3. In addition, the contractions induced by sulprostone, 17-phenyl-PGE2 and the IP-/EP1 - agonist (iloprost) were blocked by the DP-/EP1 -/EP2 -receptor antagonist (AH6809) as well as by the EP1 antagonist (SC19220). PGF2, induced small contractions which were blocked by AH6809 while fluprostenol was ineffective. These results indicate that FP-receptors are not implicated in the contraction of human pulmonary veins. These data suggest that the contractions induced by prostanoids involved TP- and EP1 -receptors in human pulmonary venous smooth muscle. British Journal of Pharmacology (2001) 134, 1671,1678; doi:10.1038/sj.bjp.0704423 [source]


    Cristiane F Freitas
    SUMMARY 1BAY 41-2272 is a potent activator of the nitric oxide-independent site of soluble guanylate cyclase and has been recently introduced as a new therapeutic agent to treat chronic pulmonary hypertension (PH) in neonatal sheep. Because the in vivo heparin,protamine interaction may lead to severe PH, the aim of the present study was to evaluate the effects of BAY 41-2272 in the PH induced by heparin,protamine interaction in anaesthetized dogs. 2Sixteen male dogs (10 mongrel dogs and six Beagles) were anaesthetized and instrumented for acquisition of mean arterial blood pressure (MABP), mean pulmonary arterial pressure (MPAP), heart rate (HR), pulmonary capillary wedge pressure (PCWP), cardiac index (CI) and indices of systemic and pulmonary vascular resistance (ISVR and IPVR, respectively). Plasma cGMP levels and Spo2 were evaluated. 3Intravenous administration of heparin (500 IU/kg) followed 3 min later by protamine (10 mg/kg) caused marked PH, as evaluated by the increase in MPAP, PCWP and IPVR. This was accompanied by a significant fall in MABP and a transient increase in HR. Infusion of BAY 41-2272 (10 µg/kg per h, starting 10 min before heparin administration) augmented plasma cGMP levels and slightly and significantly increased HR and CI, without affecting the other cardiovascular parameters. The elevation in IPVR, MPAP and PCWP triggered by the heparin,protamine interaction was significantly reduced in animals exposed to BAY 41-2272. 4In vehicle-treated dogs, the Spo2 values decreased significantly at the peak of the PH and this was significantly attenuated by treatment with BAY 41-2272. In addition, BAY 41-2272 (10 µmol/L) had no effect on the activated partial thromboplastin time of citrated plasma after the addition of heparin,protamine. 5In conclusion, BAY 41-2272 was effective in reducing canine PH induced in vivo by the heparin,protamine interaction, thus indicating its potential in the treatment of this type of disorder. [source]


    Andrew J. Read
    We conducted a mark-recapture survey of bottlenose dolphins Tursiops truncatus in the bays, sounds, and estuaries of North Carolina during July 2000, using photographic identification techniques. During this survey we took 7,682 photographs of dolphins and, of these, 3,457 images were of sufficient quality for analysis. We identified 306 dolphins from distinctive nicks and notches on their dorsal fins. Eighry-six dolphins were photographed on more than one occasion during the course of the survey; one dolphin was photographed on four separate days. We then applied the results of our photographic analyses to several mark-recapture models and examined potential violations of the assumptions of these models, including an unexpected correlation between photo quality and mark distinctiveness. Our analysis suggests that our results are robusr to possible violations of these assumptions. The resulting estimates were then scaled to account for the proportion (0.46) of unmarked dolphins in the population. Our best estimate of the number of dolphins present in the inshore waters of North Carolina during July 2000 is 1,033 with a 95% Confidence Interval of 860,1,266 (CV = 0.099). Most dolphins were found in the northern part of the study area, which includes the second largest estuarine system in the United States. [source]

    Remarkable Amphibian Biomass and Abundance in an Isolated Wetland: Implications for Wetland Conservation

    biodiversidad; declinación de anfibios; recuperación de humedales sequía; uso de suelo Abstract:,Despite the continuing loss of wetland habitats and associated declines in amphibian populations, attempts to translate wetland losses into measurable losses to ecosystems have been lacking. We estimated the potential productivity from the amphibian community that would be compromised by the loss of a single isolated wetland that has been protected from most industrial, agricultural, and urban impacts for the past 54 years. We used a continuous drift fence at Ellenton Bay, a 10-ha freshwater wetland on the Savannah River Site, near Aiken, South Carolina (U.S.A.), to sample all amphibians for 1 year following a prolonged drought. Despite intensive agricultural use of the land surrounding Ellenton Bay prior to 1951, we documented 24 species and remarkably high numbers and biomass of juvenile amphibians (>360,000 individuals; >1,400 kg) produced during one breeding season. Anurans (17 species) were more abundant than salamanders (7 species), comprising 96.4% of individual captures. Most (95.9%) of the amphibian biomass came from 232095 individuals of a single species of anuran (southern leopard frog[Rana sphenocephala]). Our results revealed the resilience of an amphibian community to natural stressors and historical habitat alteration and the potential magnitude of biomass and energy transfer from isolated wetlands to surrounding terrestrial habitat. We attributed the postdrought success of amphibians to a combination of adult longevity (often >5 years), a reduction in predator abundance, and an abundance of larval food resources. Likewise, the increase of forest cover around Ellenton Bay from <20% in 1951 to >60% in 2001 probably contributed to the long-term persistence of amphibians at this site. Our findings provide an optimistic counterpoint to the issue of the global decline of biological diversity by demonstrating that conservation efforts can mitigate historical habitat degradation. Resumen:,A pesar de la pérdida de hábitats de humedales y las declinaciones asociadas de poblaciones de anfibios, se han realizado pocos intentos para traducir las pérdidas de humedales en pérdidas mensurables en los ecosistemas. Estimamos la productividad potencial de la comunidad de anfibios que se afectaría por la pérdida de un humedal aislado que ha estado protegido de los impactos industriales, agrícolas y urbanos durante los últimos 54 años. Utilizamos un cerco de desvío en la Bahía Ellentonn, un humedal dulceacuícola de 10 ha en el Río Savannah, cerca de Aiken, Carolina del Sur (E.U.A.), para muestrear todos los anfibios durante 1 año después de una sequía prolongada. A pesar del intensivo uso agrícola del suelo alrededor de la Bahía Ellenton antes de 1951, documentamos 24 especies y números y biomasa de anfibios juveniles notablemente altos (>360,000 individuos; >1,400 kg) en una temporada reproductiva. Los anuros (17 especies) fueron más abundantes que las salamandras (7 especies), y comprendieron 96.4% de las capturas individuales. La mayor parte (95.9%) de la biomasa provino de 232095 individuos de una sola especie de anuro (Rana sphenocephala). Nuestros resultados revelaron que la resiliencia de la comunidad de anfibios a los estresantes naturales y a la alteración histórica del hábitat y la magnitud potencial de la transferencia de biomasa y energía desde los humedales aislados hacia el hábitat terrestre circundante. Atribuimos el éxito post-sequía de los anfibios a una combinación de longevidad de adultos (a menudo > 5 años), la reducción de la abundancia de depredadores y la abundancia de recursos alimenticios para las larvas. Asimismo, el incremento de la cobertura forestal alrededor de la Bahía Ellerton de < 20% en 1951 a > 60% en 2001 probablemente contribuyó a la persistencia de los anfibios a largo plazo en este sitio. Nuestros hallazgos proporcionan un contrapunto optimista al tema de la declinación global de la diversidad biológica al demostrar que los esfuerzos de conservación pueden mitigar a la degradación histórica del hábitat. [source]

    Incorporation of Recreational Fishing Effort into Design of Marine Protected Areas

    consulta pública; modelos de reservas marinas; pesca con caña; suposiciones de poza dinámica Abstract:,Theoretical models of marine protected areas (MPAs) that explore benefits to fisheries or biodiversity conservation often assume a dynamic pool of fishing effort. For instance, effort is homogenously distributed over areas from which subsets of reserves are chosen. I tested this and other model assumptions with a case study of the multiple-use Jervis Bay Marine Park. Prior to zoning of the park I conducted 166 surveys of the park's recreational fisheries, plotting the location of 16,009 anglers. I converted these plots into diagrams of fishing effort and analyzed correlates between fishing and habitat and the effect of two reserve designs,the draft and final zoning plans of the park,on the 15 fisheries observed. Fisheries were strongly correlated with particular habitats and had negatively skewed and often bimodal spatial distribution. The second mode of intensely fished habitat could be 6 SD greater than the fishery's mean allocation of effort by area. In the draft-zoning plan, sanctuary zone (no-take) area and potential subduction of fishing effort were similar. In the final plan, which was altered in response to public comment, the area of sanctuary zone increased, and the impact on fishing effort decreased. In only one case was a fishery's most intensely targeted location closed to fishing. Because of the discriminating manner with which fishers target habitats, if simple percentage targets are used for planning, sanctuary location can be adjusted to avoid existing fishing effort. According to modeled outcomes, the implication of this may be diminished reserve effectiveness. To address this, reserve area should be implicitly linked to subducted fishing effort when promoting or modeling MPAs. Resumen:,Los modelos teóricos de áreas marinas protegidas (AMPs) que exploran los beneficios para las pesquerías o la conservación de la biodiversidad a menudo asumen que hay una poza dinámica en el esfuerzo de pesca. Por ejemplo, el esfuerzo es distribuido homogéneamente en áreas en las que se seleccionan subconjuntos de reservas. Probé esta y otras suposiciones del modelo con un estudio de caso del Parque Marino Jarvis Bay. Antes de la zonificación del parque, realicé 166 muestreos de las pesquerías recreativas del parque, dibujando la localización de 16,009 pescadores con caña. Convertí estos dibujos en diagramas de esfuerzo de pesca y analicé las correlaciones entre la pesca, el hábitat y el efecto de dos diseños de reserva,el anteproyecto y los planes finales de zonificación del parque,sobre las 15 pesquerías observadas. Las pesquerías se correlacionaron fuertemente con los hábitats particulares y tenían una distribución espacial sesgada negativamente y a menudo bimodal. El segundo tipo de hábitat pescado intensivamente podría ser 6 DS mayor que la asignación promedio de esfuerzo de pesquería por unidad de área. En el anteproyecto de plan de zonificación, el área santuario (sin pesca) y la subducción potencial del esfuerzo de pesca eran similares. En el plan final, que fue alterado en respuesta a comentarios del público, el área del santuario fue incrementada, y el impacto del esfuerzo de pesca disminuyó. En solo un caso fue cerrado a la pesca la localidad de pesca más intensiva. Debido a la forma discriminada en que los pescadores eligen los hábitats, si se utilizan objetivos porcentuales simples para la planificación, la localización del santuario puede ser ajustada para evitar el esfuerzo de pesca existente. De acuerdo con los resultados del modelo, la implicación puede ser la disminución de la efectividad de la reserva. Para abordar esto, el área de la reserva debiera estar implícitamente relacionada con la reducción del esfuerzo de pesca cuando se promueven o modelan AMPs. [source]

    Genetic Diversity and Tests of the Hybrid Origin of the Endangered Yellow Larkspur

    Jason A. Koontz
    The total number of individuals in these two populations is estimated to be <100. We used allozyme and random amplified polymorphic DNA ( RAPD) markers to (1) assess levels and patterns of genetic diversity in one wild population and two cultivated populations and (2) test the hypothesis that D. luteum is of hybrid origin between D. decorum and D. nudicaule. These data will be used to aid in developing a management plan to conserve the species. The wild population maintains high levels of genetic diversity. Genetic data indicate that both cultivated populations, especially the north Sonoma population, have several allozymes and RAPD markers not found in the wild population and could be used to establish new populations of D. luteum or to enhance the diversity and size of the wild population. The allozyme data did not reveal any fixed differences between D. decorum and D. nudicaule, although allele frequencies of the putative parental populations differed. At these loci, D. luteum resembled D. nudicaule more than D. decorum . Many unique RAPD markers distinguish each of the three species. The diagnostic markers from populations of D. nudicaule and D. decorum were not additive in the putative hybrid, and these data indicate that D. luteum is not of recent hybrid origin. Conservation of the yellow larkspur should include strategies that use the cultivated populations of D. luteum, but hybridizing D. decorum and D. nudicaule to "recreate"D. luteum is not recommended. Resumen:Delphidium luteum ( Ranunculaceae), un delfinio en peligro de extinción, está restringido a dos poblaciones silvestres cerca de Bodega Bay, California. Se estima que el total de individuos en estas dos poblaciones es de <100. Utilizamos marcadores de alozimas y RAPD para (1) evaluar los niveles y patrones de diversidad genética en una población silvestre y dos poblaciones cultivadas y (2) probar la hipótesis de que D. luteum es de origen híbrido entre D. decorum y D. nudicaule. Estos datos serán utilizados para ayudar a desarrollar un plan de manejo para conservar la especie. La población silvestre mantiene altos niveles de diversidad genética. Los datos genéticos indican que ambas poblaciones cultivadas, especialmente en la población de Sonoma norte, tienen varias alozimas y marcadores RAPD que no se encuentran en poblaciones silvestres y podrían utilizarse para establecer nuevas poblaciones de D. luteum o reforzar la diversidad y tamaño de la población silvestre. Los datos de alozimas no revelaron diferencias fijas entre D. decorum y D. nudicaule, aunque las frecuencias alélicas de las poblaciones parentales putativas fueron diferentes. En estos loci, D. luteum fue más semejante a D. nudicaule que a D. decorum. Muchos marcadores RADP únicos distinguen a cada una de las tres especies. Los marcadores diagnóstico de poblaciones de D. decorum y D. nudicaule no fueron aditivos en el híbrido putativo, y estos datos indican que D. luteum no es de origen híbrido reciente. La conservación del delfinio amarillo debería incluir estrategias que usen las poblaciones cultivadas de D. luteum; sin embargo, no se recomienda la hibridación de D. decorum y D. nudicaule para "recrear" a D. luteum. [source]

    Securing the World and Challenging Civil Society: Before and After the ,War on Terror'

    Jude Howell
    ABSTRACT Following President Bush's declaration of a ,War on Terror' in 2001, governments around the world introduced a range of counter-terrorist legislation, policies and practices. These measures have affected not only human rights and civil liberties but also civil society and aid frameworks. Although the Obama administration has renounced the language of the ,War on Terror' and taken steps to revoke aspects such as water-boarding and the detention facility at Guantanamo Bay, the bulk of the legislation and practices associated with the post-9/11 global security framework remain. The cluster of papers which follow provide detailed studies of the effects of the War on Terror regime on civil society in four contexts: the USA, Spain, Kenya and Uzbekistan. In this way it lays a basis for civil society actors and aid agencies to reflect more strategically on how they should engage with security debates and initiatives in a way that best protects the spaces of civil society and the interests of minority and vulnerable groups. This introduction sets out the three key themes pursued throughout the cluster articles, namely, the selective impact of counter-terrorist measures on civil society; the particularity of civil society responsiveness to these measures; and the role of aid and diplomacy in pursuing security objectives and its consequences for civil society. [source]

    A prime inference on genetic diversity (RAPDs) in the marine fish Atherinella brasiliensis (Teleostei, Atherinopsidae) from Southern Brazil

    ACTA ZOOLOGICA, Issue 2 2010
    Maria Cristina Da Silva Cortinhas
    Abstract Da Silva Cortinhas, M. C., Glienke, C., Prioli, A. J., Noleto, R. B., Matoso, D. A. and Cestari, M. M. 2010. A prime inference on genetic diversity (RAPDs) in the marine fish Atherinella brasiliensis (Teleostei, Atherinopsidae) from Southern Brazil. ,Acta Zoologica (Stockholm) 91: 242,248 As a result of the importance of Atherinella brasiliensis in estuarine environments, random amplified polymorphic DNA (RAPD) markers were used to verify the genetic diversity in A. brasiliensis from two different places in Paranaguá Bay (Paraná State) and one from the Conceição Lagoon (Santa Catarina State). Cytogenetic data have shown a high karyotypic diversity in some populations, although in others this peculiarity demonstrates rearrangements such as heterochromatinization. In the present study, a low level of genetic structuring between the samples from Conceição Lagoon compared with the others was observed through principal coordinate analysis (PCO), analysis of molecular variance and Mantel test according to 79 RAPD markers. As this specie does not perform horizontal migration and the individuals of Conceição Lagoon are isolated, three hypotheses are proposed to explain the results: (i) similar environments may show homogeneous populations not depending on the geographical distance, (ii) because vicariant events that formed the bays occurred in a recent period, the fragmentation effects over the structuring of the genetic diversity may still be low and not totally detectable by the RAPD technique and (iii) the isolation time or the number of generations may not be enough to promote a possible differentiation and genetic structuring between the specimens of these three places. The specimens of these places present a low level of differentiation and genetic structuring so we can consider them as a unique homogeneous population. [source]

    Regional differences in kelp-associated algal assemblages on temperate limestone reefs in south-western Australia

    Thomas Wernberg
    Abstract.,Ecklonia radiata (C. Agardh) J. Agardh kelp beds , a characteristic feature of the nearshore environment along the south-west Australian coastline , contribute significantly to the coastal biodiversity in temperate Australia, yet, little is known about the organization of these macroalgal assemblages. By compiling existing and new data sets from habitat surveys, we have characterized and compared the structure of kelp-associated macroalgal assemblages in three regions (Marmion Lagoon, Hamelin Bay and the marine environment neighbouring the Fitzgerald River National Park) across more than 1000 kilometres of the south-west Australian coastline. 152 macroalgal taxa had been recognized within the three regions and this is in the range of species richness reported from other Australian and African kelp beds. The kelp-associated algal assemblages were regionally distinct, 66% of all taxa were only found in one region and only 17 taxa were found in all three regions. Adjacent regions shared an additional 13,15 taxa. The regional shifts in assemblage structure were evident in species composition of both canopy and understorey. The organization of assemblages followed a spatial hierarchy where differences in assemblage structure were larger among regions (hundreds of kilometres apart) than among sites within regions (kilometres apart) and differences among sites within region were larger than differences among quadrats within sites (metres apart). Despite this hierarchy each level of nesting contributed approximately the same to total variation in assemblage structure and these spatial patterns were stronger than temporal differences from seasons to 2,3 years. Our results suggest that local and small-scale processes contribute considerably to heterogeneity in macroalgal assemblages throughout south-western Australia, and, in particular, our results are consistent with E. radiata exerting a strong influence on macroalgal assemblage structure. Further, our study contradicts the existence of a general south-west Australian kelp assemblage, although a few species may form the core of E. radiata associations across regions. [source]

    Geomorphology of the onset area of a paleo-ice stream, Marguerite Bay, Antarctic Peninsula

    John B. Anderson
    Abstract Geomorphic features indicate that both glacial and melt-water erosion characterize the onset area of the ancestral Marguerite Ice Stream. The large size of these features indicates that they formed over repeated glacial cycles, most recently during the Last Glacial Maximum. Ice drainage within the bay and on the inner continental shelf was strongly influenced by tectonic fabric. Deep, isolated basins surrounded by rugged bedrock bathymetry characterize the innermost part of the bay. Drumlins and other streamlined features occur in the floors of these basins at depths of up to 900 m. The outer bay has three large interconnected basins. Drumlins and megaflutings within these basins indicate ice was grounded at water depths up to 1000 m. The orientations of these features show convergence of drainage from the northeast, east and south into the Marguerite paleo-ice stream. On the inner continental shelf, the ice converged into a single, wide trough dominated by mega-scale glacial lineations. This transition in geomorphic features from drumlins and megaflutings to mega-scale glacial lineations occurs at the location on the continental shelf where sedimentary strata blanket bedrock, and marks a zone of acceleration of the ice stream. The glacially sculptured geomorphic features within Marguerite Bay co-exist with anastomosing, radial and relatively straight channels, which become increasingly focused in a seaward direction. This implies that a well organized subglacial drainage system existed within the bay at some point in the past. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    A geomatics data integration technique for coastal change monitoring

    J. P. Mills
    Abstract This paper reports research carried out to develop a novel method of monitoring coastal change, using an approach based on digital elevation models (DEMs). In recent years change monitoring has become an increasingly important issue, particularly for landforms and areas that are potentially hazardous to human life and assets. The coastal zone is currently a sensitive policy area for those involved with its management, as phenomena such as erosion and landslides affect the stability of both the natural and the built environment. With legal and financial implications of failing to predict and react to such geomorphological change, the provision of accurate and effective monitoring is essential. Long coastlines and dynamic processes make the application of traditional surveying difficult, but recent advances made in the geomatics discipline allow for more effective methodologies to be investigated. A solution is presented, based on two component technologies , the Global Positioning System (GPS) and digital small format aerial photogrammetry , using data fusion to elim-inate the disadvantages associated with each technique individually. A sparse but highly accurate DEM, created using kinematic GPS, was used as control to orientate surfaces derived from the relative orientation stage of photogrammetric processing. A least squares surface matching algorithm was developed to perform the orientation, reducing the need for costly and inefficient ground control point survey. Change detection was then carried out between temporal data epochs for a rapidly eroding coastline (Filey Bay, North Yorkshire). The surface matching algorithm was employed to register the datasets and determine dif-ferences between the DEM series. Large areas of change were identified during the lifetime of the study. Results of this methodology were encouraging, the flexibility, redundancy and automation potential allowing an efficient approach to landform monitoring. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    The effect of bidirectional flow on tidal channel planforms

    Sergio Fagherazzi
    Abstract Salt marsh tidal channels are highly sinuous. For this project, ,eld surveys and aerial photographs were used to characterize the planform of tidal channels at China Camp Marsh in the San Francisco Bay, California. To model the planform evolution, we assume that the topographic curvature of the channel centreline is a key element driving meander migration. Extraction of curvature data from a planimetric survey, however, presents certain problems because simple calculations based on equally distanced points on the channel axis produce numerical noise that pollutes the ,nal curvature data. We found that a spline interpolation and a polynomial ,t to the survey data provided us with a robust means of calculating channel curvature. The curvature calculations, combined with data from numerous cross-sections along the tidal channel, were used to parameterize a computer model. With this model, based on recent theoretical work, the relationship between planform shape and meander migration as well as the consequences of bidirectional ,ow on planform evolution have been investigated. Bank failure in vegetated salt marsh channels is characterized by slump blocks that persist in the channel for several years. It is therefore possible to identify reaches of active bank erosion and test model predictions. Our results suggest that the geometry and evolution of meanders at China Camp Marsh, California, re,ect the ebb-dominated regime. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Spatial utilisation of fast-ice by Weddell seals Leptonychotes weddelli during winter

    ECOGRAPHY, Issue 3 2005
    Samantha Lake
    This study describes the distribution of Weddell seals Leptonychotes weddelli in winter (May,September 1999) at the Vestfold Hills, in Prydz Bay, East Antarctica. Specifically, we describe the spatial extent of haul-out sites in shore,fast sea-ice, commonly referred to as fast-ice. As winter progressed, and the fast-ice grew thick (ca 2 m), most of the inshore holes closed over, and the seals' distribution became restricted to ocean areas beyond land and islands. Using observations from the end of winter only, we fitted Generalised Additive Models (GAMs) to generate resource selection functions, which are models that yield values proportional to the probability of use. The models showed that seal distribution was defined mainly by distance to ice-edge and distance to land. Distance to ice-bergs was also selected for models of some regions. We present the results as maps of the fitted probability of seal presence, predicted by the binomial GAM for offshore regions, both with and without autocorrelation terms. The maps illustrate the expected distribution encompassing most of the observed distribution. On this basis, we hypothesise that propensity for the fast-ice to crack is the major determinant of Weddell seal distribution in winter. Proximity to open water and pack-ice habitats could also influence the distribution of haul-out sites in fast-ice areas. This is the first quantitative study of Weddell seal distribution in winter. Potential for regional variation is discussed. [source]