Whales as Indicators of Historical and Current Changes in the Marine Ecosystem of the Indo-Pacific Sector of the Antarctic

We review the scientific information on whales that could be indicative of historical and current changes in the ecosystem in the Indo-Pacific sector of the Antarctic. The increased krill availability in the middle of the past century as a result of the heavy harvesting of the larger baleen whale species could have been translated into better nutritional conditions for the Antarctic minke whale, resulting in a decreasing trend in the age at sexual maturity and an increasing trend in recruitment rate and hence total population size between approximately 1940 and 1970. This nutritional condition has deteriorated more recently, as revealed by a decrease in energy storage and stomach content weight since the 1980’s; these changes coincide with appreciable increases in the abundances of humpback and fin whales, which were heavily harvested in the first half of the past century. The historical demographic changes observed in the Antarctic minke whale are consistent with the pattern to be expected under the krill surplus hypothesis, with minke whales now again competing with other (recovering) baleen whale species for krill. However, these minke whales could also be using alternative feeding areas (e.g. polynias within the pack-ice) in response to the increase in abundance and geographical expansion of these other large whale species. This could provide an alternative explanation for indications from sighting surveys and population models of a decrease and then re-stabilisation of minke whale abundance in open water areas since the 1970s

Mass coral bleaching of P. versipora in Sydney Harbour driven by the 2015–2016 heatwave

© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. High-latitude coral communities are distinct from their tropical counterparts, and how they respond to recent heat wave events that have decimated tropical reefs remains unknown. In Australia, the 2016 El Niño resulted in the largest global mass coral bleaching event to date, reaching as far south as Sydney Harbour (~ 34°S). Coral bleaching was observed for the first time (affecting ca., 60% of all corals) as sea surface temperatures in Sydney Harbour remained > 2 °C above the long-term mean summer maxima, enabling us to examine whether high-latitude corals bleached in a manner described for tropical corals. Responses of the geographically cosmopolitan Plesiastrea versipora and southerly restricted Coscinaraea mcneilli were contrasted across two harbour sites, both in situ and among samples-maintained ex situ in aquaria continually supplied with Sydney Harbour seawater. While both coral taxa hosted the same species of microalgal endosymbiont (Breviolum spp; formerly clade B), only P. versipora bleached both in situ and ex situ via pronounced losses of endosymbiont cells. Both species displayed very different metabolic responses (growth, photosynthesis, respiration and calcification) and bleaching susceptibilities under elevated temperatures. Bacterial microbiome profiling, however, revealed a convergence of bacterial community composition across coral species throughout the bleaching. Corals species found in temperate regions, including the generalist P. versipora, will therefore likely be highly susceptible to future change as heat waves grow in frequency and severity unless their thermal thresholds increase. Our observations provide further evidence that high-latitude systems are susceptible to community reorganisation under climate change

Experimental feasibility of measuring the gravitational redshift of light using dispersion in optical fibers

This paper describes a new class of experiments that use dispersion in optical fibers to convert the gravitational frequency shift of light into a measurable phase shift or time delay. Two conceptual models are explored. In the first model, long counter-propagating pulses are used in a vertical fiber optic Sagnac interferometer. The second model uses optical solitons in vertically separated fiber optic storage rings. We discuss the feasibility of using such an instrument to make a high precision measurement of the gravitational frequency shift of light.Comment: 11 pages, 12 figure

Protein kinase Cepsilon is important for migration of neuroblastoma cells

<p>Abstract</p> <p>Background</p> <p>Migration is important for the metastatic capacity and thus for the malignancy of cancer cells. There is limited knowledge on regulatory factors that promote the migration of neuroblastoma cells. This study investigates the hypothesis that protein kinase C (PKC) isoforms regulate neuroblastoma cell motility.</p> <p>Methods</p> <p>PKC isoforms were downregulated with siRNA or modulated with activators and inhibitors. Migration was analyzed with scratch and transwell assays. Protein phosphorylation and expression levels were measured with Western blot.</p> <p>Results</p> <p>Stimulation with 12-<it>O</it>-tetradecanoylphorbol-13-acetate (TPA) induced migration of SK-N-BE(2)C neuroblastoma cells. Treatment with the general protein kinase C (PKC) inhibitor GF109203X and the inhibitor of classical isoforms Gö6976 inhibited migration while an inhibitor of PKCβ isoforms did not have an effect. Downregulation of PKCε, but not of PKCα or PKCδ, with siRNA led to a suppression of both basal and TPA-stimulated migration. Experiments using PD98059 and LY294002, inhibitors of the Erk and phosphatidylinositol 3-kinase (PI3K) pathways, respectively, showed that PI3K is not necessary for TPA-induced migration. The Erk pathway might be involved in TPA-induced migration but not in migration driven by PKCε. TPA induced phosphorylation of the PKC substrate myristoylated alanine-rich C kinase substrate (MARCKS) which was suppressed by the PKC inhibitors. Treatment with siRNA oligonucleotides against different PKC isoforms before stimulation with TPA did not influence the phosphorylation of MARCKS.</p> <p>Conclusion</p> <p>PKCε is important for migration of SK-N-BE(2)C neuroblastoma cells. Neither the Erk pathway nor MARCKS are critical downstream targets of PKCε but they may be involved in TPA-mediated migration.</p

Bim Nuclear Translocation and Inactivation by Viral Interferon Regulatory Factor

Viral replication efficiency is in large part governed by the ability of viruses to counteract pro-apoptotic signals induced by infection of the host cell. Human herpesvirus 8 (HHV-8) uses several strategies to block the host's innate antiviral defenses via interference with interferon and apoptotic signaling. Contributors include the four viral interferon regulatory factors (vIRFs 1–4), which function in dominant negative fashion to block cellular IRF activities in addition to targeting IRF signaling-induced proteins such as p53 and inhibiting other inducers of apoptosis such as TGFβ receptor-activated Smad transcription factors. Here we identify direct targeting by vIRF-1 of BH3-only pro-apoptotic Bcl-2 family member Bim, a key negative regulator of HHV-8 replication, to effect its inactivation via nuclear translocation. vIRF-1-mediated relocalization of Bim was identified in transfected cells, by both immunofluorescence assay and western analysis of fractionated cell extracts. Also, co-localization of vIRF-1 and Bim was detected in nuclei of lytically infected endothelial cells. In vitro co-precipitation assays using purified vIRF-1 and Bim revealed direct interaction between the proteins, and Bim-binding residues of vIRF-1 were mapped by deletion and point mutagenesis. Generation and experimental utilization of Bim-refractory vIRF-1 variants revealed the importance of vIRF-1:Bim interaction, specifically, in pro-replication and anti-apoptotic activity of vIRF-1. Furthermore, blocking of the interaction with cell-permeable peptide corresponding to the Bim-binding region of vIRF-1 confirmed the relevance of vIRF-1:Bim association to vIRF-1 pro-replication activity. To our knowledge, this is the first report of an IRF protein that interacts with a Bcl-2 family member and of nuclear sequestration of Bim or any other member of the family as a means of inactivation. The data presented reveal a novel mechanism utilized by a virus to control replication-induced apoptosis and suggest that inhibitory targeting of vIRF-1:Bim interaction may provide an effective antiviral strategy

Proliferating cell nuclear antigen acts as a cytoplasmic platform controlling human neutrophil survival

Cytosolic proliferating cell nuclear antigen (PCNA) binds to procaspases and protects human neutrophils from apoptosis

Copy number rather than epigenetic alterations are the major dictator of imprinted methylation in tumors

It has been postulated that imprinting aberrations are common in tumors. To understand the role of imprinting in cancer, we have characterized copy-number and methylation in over 280 cancer cell lines and confirm our observations in primary tumors. Imprinted differentially methylated regions (DMRs) regulate parent-of-origin monoallelic expression of neighboring transcripts in cis. Unlike single-copy CpG islands that may be prone to hypermethylation, imprinted DMRs can either loose or gain methylation during tumorigenesis. Here, we show that methylation profiles at imprinted DMRs often not represent genuine epigenetic changes but simply the accumulation of underlying copy-number aberrations (CNAs), which is independent of the genome methylation state inferred from cancer susceptible loci. Our results reveal that CNAs also influence allelic expression as loci with copy-number neutral loss-of-heterozygosity or amplifications may be expressed from the appropriate parental chromosomes, which is indicative of maintained imprinting, although not observed as a single expression foci by RNA FISH

Significant variation in transformation frequency in Streptococcus pneumoniae

The naturally transformable bacterium Streptococcus pneumoniae is able to take up extracellular DNA and incorporate it into its genome. Maintaining natural transformation within a species requires that the benefits of transformation outweigh its costs. Although much is known about the distribution of natural transformation among bacterial species, little is known about the degree to which transformation frequencies vary within species. Here we find that there is significant variation in transformation frequency between strains of Streptococcus pneumoniae isolated from asymptomatic carriage, and that this variation is not concordant with isolate genetic relatedness. Polymorphism in the signalling system regulating competence is also not causally related to differences in transformation frequency, although this polymorphism does influence the degree of genetic admixture experienced by bacterial strains. These data suggest that bacteria can evolve new transformation frequencies over short evolutionary timescales. This facility may permit cells to balance the potential costs and benefits of transformation by regulating transformation frequency in response to environmental conditions