Lifestyle and Ice: The Relationship between Ecological Specialization and Response to Pleistocene Climate Change

Major climatic changes in the Pleistocene had significant effects on marine organisms and the environments in which they lived. The presence of divergent patterns of demographic history even among phylogenetically closely-related species sharing climatic changes raises questions as to the respective influence of species-specific traits on population structure. In this work we tested whether the lifestyle of Antarctic notothenioid benthic and pelagic fish species from the Southern Ocean influenced the concerted population response to Pleistocene climatic fluctuations. This was done by a comparative analysis of sequence variation at the cyt b and S7 loci in nine newly sequenced and four re-analysed species. We found that all species underwent more or less intensive changes in population size but we also found consistent differences between demographic histories of pelagic and benthic species. Contemporary pelagic populations are significantly more genetically diverse and bear traces of older demographic expansions than less diverse benthic species that show evidence of more recent population expansions. Our findings suggest that the lifestyles of different species have strong influences on their responses to the same environmental events. Our data, in conjunction with previous studies showing a constant diversification tempo of these species during the Pleistocene, support the hypothesis that Pleistocene glaciations had a smaller effect on pelagic species than on benthic species whose survival may have relied upon ephemeral refugia in shallow shelf waters. These findings suggest that the interaction between lifestyle and environmental changes should be considered in genetic analyses.     

Patterns and Emerging Trends in Global Ocean Health

International and regional policies aimed at managing ocean ecosystem health need quantitative and comprehensive indices to synthesize information from a variety of sources, consistently measure progress, and communicate with key constituencies and the public. Here we present the second annual global assessment of the Ocean Health Index, reporting current scores and annual changes since 2012, recalculated using updated methods and data based on the best available science, for 221 coastal countries and territories. The Index measures performance of ten societal goals for healthy oceans on a quantitative scale of increasing health from 0 to 100, and combines these scores into a single Index score, for each country and globally. The global Index score improved one point (from 67 to 68), while many country-level Index and goal scores had larger changes. Per-country Index scores ranged from 41–95 and, on average, improved by 0.06 points (range -8 to +12). Globally, average scores increased for individual goals by as much as 6.5 points (coastal economies) and decreased by as much as 1.2 points (natural products). Annual updates of the Index, even when not all input data have been updated, provide valuable information to scientists, policy makers, and resource managers because patterns and trends can emerge from the data that have been updated. Changes of even a few points indicate potential successes (when scores increase) that merit recognition, or concerns (when scores decrease) that may require mitigative action, with changes of more than 10–20 points representing large shifts that deserve greater attention. Goal scores showed remarkably little covariance across regions, indicating low redundancy in the Index, such that each goal delivers information about a different facet of ocean health. Together these scores provide a snapshot of global ocean health and suggest where countries have made progress and where a need for further improvement exists.     

A DEVD-Inhibited Caspase Other than CPP32 Is Involved in the Commitment of Cerebellar Granule Neurons to Apoptosis Induced by K+ Deprivation

Abstract: Cultured cerebellar granule neurons undergo apoptosis when switched from a medium containing depolarizing levels of K⁺ (25 mM KCI) to medium containing lower levels of K⁺ (5 mM KCI). We used this paradigm to investigate the role of caspases in the death process. Two broad-spectrum caspase inhibitors, tert-butoxycarbonyl-Asp·(O-methyl)·fluoromethyl ketone and benzyloxycarbonyl-Val-Ala-Asp·fluoromethyl ketone, significantly reduced cell death (90 and 60%, respectively) at relatively low concentrations (10–25 µM), suggesting that caspase activation is involved in the apoptotic process. DNA fragmentation, a hallmark of apoptosis, was also reduced by these caspase inhibitors, suggesting that caspase activation occurred upstream of DNA cleavage in the sequence of events leading to cell death. As a step toward identifying the caspase(s) involved, the effects of N-acetyl Tyr-Val-Ala-Asp·chloromethyl ketone (YVAD·cmk), an interleukin-1β converting enzyme-preferring inhibitor, and N-acetyl Asp-Glu-Val-Asp·fluoromethyl ketone (DEVD·fmk), a CPP32-preferring inhibitor, were also evaluated. YVAD·cmk provided only modest (<20%) protection and only at the highest concentration (100 µM) tested, suggesting that interleukin-1β converting enzyme and/or closely related caspases were not involved. In comparison, DEVD·fmk inhibited cell death by up to 50%. Western blot analyses, however, failed to detect an increase in processing/activation of CPP32 or in the proteolysis of a CPP32 substrate, poly(ADP-ribose) polymerase, during the induction of apoptosis in granule neurons. Similarly, the levels of Nedd2, a caspase that is highly expressed in the brain and that is partially inhibited by DEVD·fmk, also remained unaffected in apoptotic neurons undergoing apoptosis. These results suggest that a DEVD-sensitive caspase other than CPP32 or Nedd2 mediates the induction of apoptosis in K⁺-deprived granule neurons.     

Reproductive biology of South American Bothriochloa (Poaceae: Andropogoneae)

The reproductive biology of 13 South American taxa of Bothriochloa was studied. All surveyed species reproduce sexually and are self-compatible. Several elements also point to self-pollination as their main breeding system: (i) bud pollination that occurs in most species enhancing cleistogamy, (ii) presence of pits in the glumes that impede the opening of flowers and (iii) reduction in the number of stamens, a trend associated with outbreeding.     

Beiträge zur Flora von Innsbruck

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Ueber Symbiose von Bacterien (in Zoogloeaform) mit der Alge Gleocapsa polydermatica. Ktz

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