Gulls and plovers: host vigilance,kleptoparasite success and a model of kleptoparasite detection

Much interest has focused on the conflict between feeding and vigilance. However, because predator attacks are rarely observed, the adaptive value of time spent vigilant (or non-vigilant through feeding) is difficult to ascertain. On the assumption that the tactics used by plovers (lapwings, Vanellus vanellus and golden plover, Pluvialis apricaria) to avoid attack by kleptoparasitic black-headed gulls (Larus ridibundus) and predators are similar, we develop a model predicting the probability of a gull being detected over any distance. The assumptions of the model are that (a) plovers are attacked whilst nonvigilant (crouching and handling prey) and (b) attacks lasting longer than the target plover's non-vigilant period will be detected. Over many distances there was a fairly close match between the observed and expected risk of the gull being detected. The match was better when the model assumed gulls waited 1 s prior to attacking plovers with large profitable worms. The risks of kleptoparasitism and predation are compared and the adaptive value of the close match between observed and expected curves is discussed.     

Confocal Microscopic Observations on Microtubular Cytoskeleton Changes During Megasporogenesis and Megagametogenesis in Phaius tankervilliae (Aiton) Bl.

In nun orchid (Phaius tankervilliae (Alton) B1. ) embryo sac development follows the monosporic pattern. Changes in the pattern of organization of the microtubular cytoskeleton during megasporogenesis and megagametogenesis in this orchid were studied using the immunofluorescence technique and eonfocal microscopy. At the initial stage of development the microtubules in the arehesporium were randomly oriented into a network. Later the archesporial cell elongated to form the megasporocyte. The cytoskeleton in the elongated megasporoeyte was radially organized in which microtubules extending from the nuclear envelope to the peripheral region of the cell. The megasporoeyte then underwent meiosis 1 to form a dyad. The dyad cell at the chalazal end was larger than the cell at the micropylar end. Microtubules in the dyad cell were radially oriented. The dyad underwent meiosis to give rise to a linear array of four megaspores (i. e. tetrad formation). The chalazal-far most megaspore survived and became the functional megaspore, which contained a set of randomly oriented microtubules. The microtubules in the other 3 megaspore disappeared as the cells degenerated. The functional megaspore then underwent mitotic division giveing rise to a 2 nucleate embryo sac. The nuclei of the 2-nucleate embryo sac were separated by a set of longitudinally oriented microtubules which ran parallel to the long axis of the embryo sac. Each nucleus in the embryo sac was surrounded by a set of perinuelear microtubules. The gnucleate embryo sac again underwent mitotic division to form a 4-nucleate embryo sac. The division of the two nuclei was synchronous. But the orientation of the division plan of the two spindles was different (i. e. the spindle microtubules at the chalazal end ran parallel with the long axis of the embryo sac and those at the mieropylar end ran at right angle to the axis of the embryo sac). The 4 nuclei of the 4-nucleate embryo sac were all tightly surrounded by randomly oriented microtubules. Later the paired nuclei at the micropylr end and at the chalazal end as well underwent mitotic division in seguence. At this time when the embryo sac had reached the 8-nucleate embryo sac stage. The pattern of organization of the microtubules was very complex. Initially the nuclei were surrounded by a set of randomly oriented microtubules, but after the two polar nuclei had moved to the central region of the embryo sac, three different organizational zones of microtubules appeared, viz: a randomly oriented set of microtubules surrounding each nucleus in the chalazal zone: a set (in the form of a basket) of cortical microtubules which surrounded the vacuoles and the two polar nuclei in the central zone and a loosely knitted network of microtubules surrounding the nucleus that later became the egg cell nucleus in the micropylar zone. The two nuclei that would become the nuclei of the synergids were surrounded by a set of more densely packed mierotubules. Towards far the most micropylar end some microtubules formed thick bundles. The site of appearance of these thick bundles coincided with the site of development of the filiform apparatus. The pattern of microtubule organization after cellularization (i. e. at the beginning of embryo sac maturation) did not change much. The author's results indicated that various patterns of microtubule organization observed in the developing embryo sac of nun orchid reflected the complexity and dynamism of the embryo sac.     

Whole community estimates of macroalgal pigment concentration within two southern New Zealand kelp forests1

Light availability is a fundamental factor that controls the productivity and distribution of macroalgae and is highly variable, both spatially and temporally, in subtidal coastal systems. Our comprehension of how macroalgae respond to such variability is a significant knowledge gap that limits our understanding of how light influences the structure and productivity of these environments. Here, we examined the pigment characteristics of individual species, and for the first time the whole community, within one low‐light, and one high‐light kelp‐forest system in southern New Zealand. The aim was to quantify the range of pigmentation seen within the two kelp‐forests which differed in irradiance regime. Light availability was 33% and 64% greater at the high‐light compared to the low‐light site at 2 and 10 m depth, respectively. Results suggested Phaeophyceae species at deeper depths in the low‐light site may be living at the edge of their photosynthetic ability and pigment synthesis appeared significantly restricted. Even with greater investment in the pigment fucoxanthin, biomass of Phaeophyceae species was significantly lower in the low‐light site. Highly pigmented Rhodophyceae species made a greater proportional contribution to community biomass within the low‐light site where they likely possessed a photosynthetic advantage. This work helps explain discrepancies in community structure between the two study sites and explores the complex relationship between irradiance and photoacclimation. The comparison of community pigment concentration holds potential as a tool for assessing the relative degree of photoacclimation occurring between sites and provides a proxy of photosynthetic cost under a specific light regime.     

Clinical,Virological and Immunological Features from Patients Infected with Re-Emergent Avian-Origin Human H7N9 Influenza Disease of Varying Severity in Guangdong Province

BackgroundThe second wave of avian influenza H7N9 virus outbreak in humans spread to the Guangdong province of China by August of 2013 and this virus is now endemic in poultry in this region.MethodsFive patients with H7N9 virus infection admitted to our hospital during August 2013 to February 2014 were intensively investigated. Viral load in the respiratory tract was determined by quantitative polymerase chain reaction (Q-PCR) and cytokine levels were measured by bead-based flow cytometery.ResultsFour patients survived and one died. Viral load in different clinical specimens was correlated with cytokine levels in plasma and broncho-alveolar fluid (BALF), therapeutic modalities used and clinical outcome. Intravenous zanamivir appeared to be better than peramivir as salvage therapy in patients who failed to respond to oseltamivir. Higher and more prolonged viral load was found in the sputum or endotracheal aspirates compared to throat swabs. Upregulation of proinflammatory cytokines IP-10, MCP-1, MIG, MIP-1α/β, IL-1β and IL-8 was found in the plasma and BALF samples. The levels of cytokines in the plasma and viral load were correlated with disease severity. Reactivation of herpes simplex virus type 1(HSV-1) was found in three out of five patients (60%).ConclusionExpectorated sputum or endotracheal aspirate specimens are preferable to throat swabs for detecting and monitoring H7N9 virus. Severity of the disease was correlated to the viral load in the respiratory tract as well as the extents of cytokinemia. Reactivation of HSV-1 may contribute to clinical outcome.     

Electrical stimulation influences satellite cell proliferation and apoptosis in unloading-induced muscle atrophy in mice

Muscle atrophy caused by disuse is accompanied by adverse physiological and functional consequences. Satellite cells are the primary source of skeletal muscle regeneration. Satellite cell dysfunction, as a result of impaired proliferative potential and/or increased apoptosis, is thought to be one of the causes contributing to the decreased muscle regeneration capacity in atrophy. We have previously shown that electrical stimulation improved satellite cell dysfunction. Here we test whether electrical stimulation can also enhance satellite cell proliferative potential as well as suppress apoptotic cell death in disuse-induced muscle atrophy. Eight-week-old male BALB/c mice were subjected to a 14-day hindlimb unloading procedure. During that period, one limb (HU-ES) received electrical stimulation (frequency: 20 Hz; duration: 3 h, twice daily) while the contralateral limb served as control (HU). Immunohistochemistry and western blotting techniques were used to characterize specific proteins in cell proliferation and apoptosis. The HU-ES soleus muscles showed significant improvement in muscle mass, cross-sectional area, and peak tetanic force relative to the HU limb (p<0.05). The satellite cell proliferative activity as detected within the BrdU+/Pax7+ population was significantly higher (p<0.05). The apoptotic myonuclei (detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) and the apoptotic satellite cells (detected by cleaved Poly [ADP-ribose] polymerase co-labeled with Pax7) were reduced (p<0.05) in the HU-ES limb. Furthermore the apoptosis-inducing factor and cleaved caspase-3 were down-regulated while the anti-apoptotic Bcl-2 protein was up-regulated (p<0.05), in the HU-ES limb. These findings suggest that the electrical stimulation paradigm provides an effective stimulus to rescue the loss of myonuclei and satellite cells in disuse muscle atrophy, thus maintaining a viable satellite cell pool for subsequent muscle regeneration. Optimization of stimulation parameters may enhance the outcome of the intervention.     

Interfacing similarity search software with the sequence retrieval system ACNUC

A method of interfacing sequence similarity search softwarewith the fast sequence retrieval system ACNUC is described.The method is written in FORTRAN 77 and is straightforward toimplement because no textprocessing code is required —a minimum of 12 extra lines of FORTRAN provided the interfacefor most applications. The method is also efficient, since sequencesare located by simple indexing techniques, with no linear searchesof large database files necessary. Received on November 20, 1986; accepted on January 8, 1987     

Gene expression changes in GABA(A) receptors and cognition following chronic ketamine administration in mice

Ketamine is a well-known anesthetic agent and a drug of abuse. Despite its widespread use and abuse, little is known about its long-term effects on the central nervous system. The present study was designed to evaluate the effect of long-term (1- and 3-month) ketamine administration on learning and memory and associated gene expression levels in the brain. The Morris water maze was used to assess spatial memory and gene expression changes were assayed using Affymetrix Genechips; a focus on the expression of GABA(A) receptors that mediate a tonic inhibition in the brain, was confirmed by quantitative real-time PCR and western blot. Compared with saline controls, there was a decline in learning and memory performance in the ketamine-treated mice. Genechip results showed that 110 genes were up-regulated and 136 genes were down-regulated. An ontology analysis revealed the most significant effects of ketamine were on GABA(A) receptors. In particular, there was a significant up-regulation of both mRNA and protein levels of the alpha 5 subunit (Gabra5) of the GABA(A) receptors in the prefrontal cortex. In conclusion, chronic exposure to ketamine impairs working memory in mice, which may be explained at least partly by up-regulation of Gabra5 subunits in the prefrontal cortex.     

Solubilization and assay of a colony-stimulating factor receptor from murine macrophages

The colony-stimulating factor, CSF-1, selectively stimulates the survival, proliferation, and differentiation of mononuclear phagocytes. The solubilization, assay, and characteristics of the CSF-1 receptor from the J774.2 murine macrophage cell line are described. The recovery of cell-surface receptor in the postnuclear supernatant membrane fraction of hypotonically disrupted cells was 76%. Recovery of the ligand binding activity of the receptor after solubilization of this fraction with 1% Triton X-100 was approximately 150%. The binding of 125I-CSF-1 to intact cells and membrane preparations was consistent with the existence of a single class of high-affinity receptor sites. In contrast, the equilibrium binding of 125I-CSF-1 to the solubilized postnuclear fraction indicated the existence of two distinct classes of binding site (apparent Kds 0.15 nM and 10 nM). A rapid assay was developed for the high-affinity sites, which were shown to be associated with the CSF-1 receptor. The function of the low-affinity sites, which have not been demonstrated on intact cells or cell membranes and which are 13 times more abundant than the high-affinity sites, is unknown. The solubilized high-affinity receptor-CSF-1 complex was stable on storage at 0 degrees C and -70 degrees C but dissociated at 37 degrees C. Dissociation also occurred at 0 degrees C in buffers of low pH (4.0) or high ionic strength (0.7 M NaCl).     

Human mesenchymal stem cells protect human islets from pro-inflammatory cytokines

Transplantation of human islets is an attractive alternative to daily insulin injections for patients with type 1 diabetes. However, the majority of islet recipients lose graft function within five years. Inflammation is a primary contributor to graft loss, and inhibiting pro-inflammatory cytokine activity can reverse inflammation mediated dysfunction of islet grafts. As mesenchymal stem cells (MSCs) possess numerous immunoregulatory properties, we hypothesized that MSCs could protect human islets from pro-inflammatory cytokines. Five hundred human islets were co-cultured with 0.5 or 1.0 × 10(6) human MSCs derived from bone marrow or pancreas for 24 hours followed by 48 hour exposure to interferon-γ, tumor necrosis factor-α and interleukin 1β. Controls include islets cultured alone (± cytokines) and with human dermal fibroblasts (± cytokines). For all conditions, glucose stimulated insulin secretion (GSIS), total islet cellular insulin content, islet β cell apoptosis, and potential cytoprotective factors secreted in the culture media were determined. Cytokine exposure disrupted human islet GSIS based on stimulation index and percentage insulin secretion. Conversely, culture with 1.0 × 10(6) bMSCs preserved GSIS from cytokine treated islets. Protective effects were not observed with fibroblasts, indicating that preservation of human islet GSIS after exposure to pro-inflammatory cytokines is MSC dependent. Islet β cell apoptosis was observed in the presence of cytokines; however, culture of bMSCs with islets prevented β cell apoptosis after cytokine treatment. Hepatocyte growth factor (HGF) as well as matrix metalloproteinases 2 and 9 were also identified as putative secreted cytoprotective factors; however, other secreted factors likely play a role in protection. This study, therefore, demonstrates that MSCs may be beneficial for islet engraftment by promoting cell survival and reduced inflammation.