Influences of salinity on the physiology and distribution of the Arctic coralline algae,Lithothamnion glaciale (Corallinales,Rhodophyta)

In Greenland, free‐living red coralline algae contribute to and dominate marine habitats along the coastline. Lithothamnion glaciale dominates coralline algae beds in many regions of the Arctic, but never in Godthåbsfjord, Greenland, where Clathromorphum sp. is dominant. To investigate environmental impacts on coralline algae distribution, calcification and primary productivity were measured in situ during summers of 2015 and 2016, and annual patterns of productivity in L. glaciale were monitored in laboratory‐based mesocosm experiments where temperature and salinity were manipulated to mimic high glacial melt. The results of field and cold‐room measurements indicate that both L. glaciale and Clathromorphum sp. had low calcification and photosynthetic rates during the Greenland summer (2015 and 2016), with maximum of 1.225 ± 0.17 or 0.002 ± 0.023 μmol CaCO ₃ · g^?1 · h^?1 and ?0.007 ±0.003 or ?0.004 ± 0.001 mg O₂ · L^?1 · h^?1 in each species respectively. Mesocosm experiments indicate L. glaciale is a seasonal responder; photosynthetic and calcification rates increase with annual light cycles. Furthermore, metabolic processes in L. glaciale were negatively influenced by low salinity; positive growth rates only occurred in marine treatments where individuals accumulated an average of 1.85 ± 1.73 mg · d^?1 of biomass through summer. These results indicate high freshwater input to the Godthåbsfjord region may drive the low abundance of L . glaciale , and could decrease species distribution as climate change increases freshwater input to the Arctic marine system via enhanced ice sheet runoff and glacier calving.     

Marine Telemetry and the Conservation and Management of Risk to Seal Species in Canada and Australia

Marine telemetry expands the knowledge of the biology of marine species at risk: their life cycles, activities, interactions, habitats, and threats. Four seal species in Canada and Australia are faced with distinctive and divergent management problems. This article examines their conservation status, legal protection, and the role that telemetry has played, or could play, in providing previously unavailable information to help meet conservation goals. The value of telemetry data to minimize fisheries mortality of one species has been demonstrated in Australia. Despite there being significant telemetry data for the other species, policy and management have not yet responded.     

Inhibition of neutrophil oxidative burst and granule secretion by Wortmannin: Potential role of MAP kinase and renaturable kinases

Exposure of neutrophils to a variety of agonists including soluble chemoattractant peptides and cytokines results in degranulation and activation of the oxidative burst (effector functions) that are required for bacterial killing. At present, the signaling pathways regulating these important functions are incompletely characterized. Mitogen-activated protein (MAP) kinases (MAPK) as well as members of a family of “renaturable kinases” are rapidly activated in neutrophils in response to diverse physiological agonists, suggesting that they may regulate cell activation. Antagonists of phosphatidyl inositol-3-(OH) kinase (PI3-kinase) such as wortmannin (Wtmn) inhibit these effector responses as well as certain of the above-mentioned kinases, leading to the suggestion that these enzymes lie downstream of PI3-kinase in the pathway regulating the oxidative burst and granule secretion. However, an apparent discrepancy exists in that, while virtually obliterating activity of PI3-kinase and the oxidase at low concentrations (ID₅₀ < 20 nM), Wtmn has only variable inhibitory effects on MAPK even at substantially higher concentrations (75–100 nM). This raises the possibility that the inhibitory effects of Wtmn are mediated via other enzyme systems. The purpose of the current study was therefore to compare the effects of Wtmn on PI3-kinase activity and on the chemoattractant-activated kinases, and to determine the potential relationship of these pathways to microbicidal responses. In human neutrophils, both the oxidative burst and granule secretion induced by fMLP were inhibited by Wtmn but at markedly different concentrations: the oxidative burst was inhibited with an ID₅₀ of <5 nM while granule secretion was only partially inhibited at concentrations exceeding 75 nM. Activation of both MEK-1 and MAPK in response to fMLP was only partially inhibited by high doses of Wtmn (ID₅₀ of > 100 nM and ≡75 nM, respectively). In contrast, Wtmn potently inhibited fMLP-induced activation of the 63 and 69 kDa renaturable kinases (ID₅₀ ≡ 5–10 nM). We speculate that the renaturable kinases may be involved in the regulation of the oxidative burst, whereas the MAPK pathway may play a role in other neutrophil functions such as granule secretion. J. Cell. Physiol. 172:94–108, 1997. © 1997 Wiley-Liss, Inc.     

Brucella Omp2a and Omp2b porins: single channel measurements and topology prediction

Brucella usually carry two highly homologous genes (omp2a and omp2b) for porin-like proteins. In several B. abortus biovars the omp2a gene has a large deletion compared to other Brucella omp2's. In this study we have measured Omp2 pore activity in planar bilayers. Omp2b exhibits well-defined trimeric channel activity whilst Omp2a forms monomeric pores of variable size which are smaller than Omp2b. No sequence homology exists between Omp2 and porins of known structure, so hydrophobic moment analysis has been used to model their membrane topology. From this it appears likely that the deletion removes the crucial L3 internal loop.     

1-Thiazol-2-yl-N-3-methyl-1H-pyrozole-5-carboxylic acid derivatives as antitumor agents

A class of substituted 1-thiazol-2-yl-N-3-methyl-1H-pyrozole-5-carboxylic acid derivatives was found to have potent anti-proliferative activity against a broad range of tumor cell lines. A compound from this class (14) was profiled across a broad panel of hematologic and solid tumor cancer cell lines demonstrating cell cycle arrest at the G0/G1 interphase and has potent anti-proliferative activity against a distinct and select set of cancer cell types with no observed effects on normal human cells. An example is the selective inhibition of human B-cell lymphoma cell line (BJAB). Compound 14 was orally bioavailable and tolerated well in mice. Synthesis and structure activity relationships (SAR) in this series of compounds are discussed.     

Effects of Wind-induced Spatial Variation in Water Temperature and Zooplankton Concentration on the Growth of Young-of-the-year Smallmouth Bass, Micropterus dolomieu

Synopsis Young-of-the-year (YOY) smallmouth bass, Micropterus dolomieu, spend their first summer in littoral areas near their nests. Evidence indicates that nests of smallmouth bass in Lake Opeongo, Ontario, Canada are more abundant in downwind locations than in upwind areas. We hypothesize that wind-induced lower water temperatures and food availability in upwind nesting areas lead to lower growth rates of YOY bass in upwind than in downwind nesting areas. We show that water temperatures were 0.6–1.3 °C higher in downwind than upwind littoral areas during the period from mid-June to mid-July, when the YOY bass were on or near their nests. Although quite variable, zooplankton concentrations were also higher at downwind sites. In addition, bioenergetic simulations based on time series of field-measured temperatures predicted higher growth rates of YOY bass in the downwind sites. Growth rates based on sequential sampling of bass fry from their nests did not, however, differ statistically between upwind and downwind sites, although fry consistently weighed more downwind than upwind in the basin with the longer fetch possibly due to earlier spring warming. Our hypothesis is thus only partially supported and we call for further research on effects of spatial gradients on smallmouth bass life history.     

DAP5 promotes cap-independent translation of Bcl-2 and CDK1 to facilitate cell survival during mitosis

DAP5 is an eIF4G protein previously implicated in mediating cap-independent translation in response to cellular stresses. Here we report that DAP5 is crucial for continuous cell survival in nonstressed cells. The knockdown of endogenous DAP5 induced M phase-specific caspase-dependent apoptosis. Bcl-2 and CDK1 were identified by two independent screens as DAP5 translation targets. Notably, the activity of the Bcl-2 IRES was reduced in DAP5 knockdown cells and a selective shift of Bcl-2 mRNA toward light polysomal fractions was detected. Furthermore, a functional IRES was identified in the 5'UTR of CDK1. At the cellular level, attenuated translation of CDK1 by DAP5 knockdown decreased the phosphorylation of its M phase substrates. Ectopic expression of Bcl-2 or CDK1 proteins partially reduced the extent of caspase activation caused by DAP5 knockdown. Thus, DAP5 is necessary for maintaining cell survival during mitosis by promoting cap-independent translation of at least two prosurvival proteins.