Drastic changes in lake ecosystem development as a consequence of flax retting: a multiproxy palaeolimnological study of Lake Kooraste Linajärv,Estonia

This study demonstrates the power of multiproxy palaeolimnological analyses in investigating environmental changes in the Lake Kooraste Linajärv ecosystem through historical time in response to flax retting. Flax retting history was proven by applying pollen and macrofossil evidence and by using several biotic and geochemical proxies on a sediment core. Continuous findings of flax pollen and macrofossil remains in lake sediments were considered as strong evidence for the occurrence of retting. Analyses of the well-dated sediment core show the consequences of flax retting in the lake. As a result, the once clear soft water oligotrophic endorheic lake with limited sedimentation has turned into a hypertrophic high-sedimentation lake with anoxic bottom water, strong stratification and intense water blooms. Despite the fact that flax retting was forbidden in Estonia around ad 1950s and retting has not occurred over the last six decades, anthropogenic alterations were so pervasive in the past, that they have prevented any lake water improvements until the present-day.     

Ectomycorrhizas of <Emphasis Type="Italic">Coltricia</Emphasis> and <Emphasis Type="Italic">Coltriciella</Emphasis> (Hymenochaetales,Basidiomycota) on Caesalpiniaceae,Dipterocarpaceae and Myrtaceae in Seychelles

Ectomycorrhizal fungi, especially basidiomycetes, have repeatedly evolved from saprotrophic ancestors. Using rDNA internal transcribed spacer and large subunit sequences, we demonstrate that four species of Coltricia and Coltriciella form ectomycorrhiza with the native Vateriopsis seychellarum (Dipterocarpaceae) and Intsia bijuga (Caesalpiniaceae) as well as the introduced Eucalyptus robusta (Myrtaceae) in Seychelles. Coltricia and Coltriciella species share a thin, orange-brown to dark brown mantle and extremely thick, clampless hyphae. Phylogenetic analyses placed Coltriciella monophyletic within Coltricia. This study provides further evidence that fruiting habit on dead wood does not indicate saprotrophic lifestyle.     

Mitochondrial activity of frozen-thawed spermatozoa assessed by MitoTracker Deep Red 633

The present study was conducted to find a more objective method of evaluating sperm quality than the current subjective motility evaluations by testing the applicability of a novel fluorescent probe, Mitotracker Deep Red 633 (M-22426), for measuring the mitochondrial activity of spermatozoa both after freezing/thawing (PT) and after swim-up selection (SU), using flow cytometry (FC). The results from FC were compared to those of conventional microscopic motility evaluations and of computer-assisted sperm analysis (CASA) as well as to the fertility obtained after AI in the field. Semen from six Estonian Holstein bulls, processed when the sires were aged 3, 5, and 7 years, was included in the experiment. Sperm motility (measured either subjectively or by means of CASA) was always significantly (p<0.01-0.001) higher in the spermatozoa recovered by SU, for any of the age groups considered, or even when combining the age groups. Motility (measured subjectively) after SU was significantly (p<0.05) higher when bulls reached 7 years of age, compared to earlier collection ages, but no differences were registered between ages for CASA-assessed motility, either after SU or immediately PT. The numbers of spermatozoa with high red fluorescence also increased after SU: p<0.05 (for semen from bulls aged 3 years), p<0.001 (5 years), p<0.001 (7 years), and p<0.001 when all age groups were combined. The proportion of spermatozoa with high mitochondrial activity as determined by Mitotracker Deep Red 633 correlated with sperm motility (p<0.01) both PT and after SU, but not with the fertility results. In conclusion, MitoTracker Deep Red 633 seems to be a reliable marker for frozen-thawed bovine semen viability both PT and after SU.     

Does cleansing of frozen-thawed bull semen before assessment provide samples that relate better to potential fertility?

The present study estimated, in vitro, the influence of two cleansing methods on sperm parameters post-thaw and their relation to the fertility of the frozen-thawed semen after AI. Frozen semen from six 1-year-old Swedish Red and White dairy bulls with a range in fertility (as 56d-Non-Return Rates, i.e., 56d-NRR) of 62.2-70.7% among batches was tested, using three batches of semen per bull. From each batch, individual straws were analyzed immediately after thawing (PT, control) or pooled and subjected to a swim-up procedure (SU) or washing by centrifugation/re-suspension (W) prior to in vitro assessments. Subjective and computerized measurements of sperm motility and of concentration, morphology, and membrane integrity were recorded. SU provided spermatozoa with significantly better motility, acrosome-, midpiece- and tail morphology and membrane integrity compared to either control or W treatment. Significant, albeit low, correlations among single sperm parameters and NRR were found (after PT for tail abnormalities (r = 0.49) and average path velocity, VAP (r = 0.47), after SU for total sperm motility with CASA (r = 0.50) and after W only for non-linear motility (r = -0.69)). SU of frozen-thawed bull semen is a simple preparation procedure that selects for sperm motility and membrane integrity, essential parameters for fertilization. It helps in vitro assessment of the semen and provides a significant, although low, relationship to the fertility of the assayed semen.     

Stepwise Splitting of Ribosomal Proteins from Yeast Ribosomes by LiCl

Structural studies have revealed that the core of the ribosome structure is conserved among ribosomes of all kingdoms. Kingdom-specific ribosomal proteins (r-proteins) are located in peripheral parts of the ribosome. In this work, the interactions between rRNA and r-proteins of eukaryote Saccharomyces cerevisiae ribosome were investigated applying LiCl induced splitting and quantitative mass spectrometry. R-proteins were divided into four groups according to their binding properties to the rRNA. Most yeast r-proteins are removed from rRNA by 0.5–1 M LiCl. Eukaryote-specific r-proteins are among the first to dissociate. The majority of the strong binders are known to be required for the early ribosome assembly events. As compared to the bacterial ribosome, yeast r-proteins are dissociated from rRNA at lower ionic strength. Our results demonstrate that the nature of protein-RNA interactions in the ribosome is not conserved between different kingdoms.     

Accounting for differential migration strategies between age groups to monitor raptor population dynamics in the eastern Black Sea flyway

Migration counts can offer a cost-effective method for monitoring the state of migrant raptor populations. However, differential migration strategies between inexperienced juveniles and experienced non-juveniles are rarely accounted for when inferring population trends from raptor migration counts. Since 2011, the Batumi Raptor Count (BRC) monitors the autumn migration of more than 1 million raptors along the eastern Black Sea coast in the Republic of Georgia. We also systematically sampled age information to assess differential migration timing between age groups and estimate age-specific linear trends in abundance between 2011 and 2018 for eight focal species. In so doing we aimed (1) to reassess the global relevance of BRC counts for each species and the potential for monitoring abundance of juveniles and non-juveniles, and (2) to identify demographic changes underlying recent trends in overall abundance. We found that the mean annual passage of non-juveniles at Batumi represents at least 1% of the estimated global breeding population of five study species. As expected, counts of juveniles were more variable than counts of non-juveniles. Yet despite our short monitoring period our models had sufficient statistical power to detect changes in abundance of 10%/year or less for at least one age group in all species except Pallid Harrier Circus macrourus. Our results indicate stable abundance and demography for half of the study species. We also found strong and significant increases in the abundance of Black Kites Milvis migrans and Short-toed Eagles Circaetus gallicus that were primarily due to increasing numbers of non-juveniles. By contrast, juvenile Montagu's Harriers Circus pygargus and Booted Eagles Hieraaetus pennatus significantly decreased in abundance. The first decade of BRC surveys offers an important benchmark for monitoring raptor populations using the eastern African–Palearctic flyway in the 21st century. We discuss possible causes of the observed trends and hope our work will stimulate demographic monitoring at migration count sites.     

Closing the gap between plant ecology and Quaternary palaeoecology

Ecology and Quaternary palaeoecology have largely developed as parallel disciplines. Although both pursue related questions, information exchange is often hampered by particularities of the palaeoecological data and a communication gap has been perceived between the disciplines. Based on selected topics and developments mainly in Quaternary palaeoecology, we show that both disciplines have converged somewhat during recent years, while we still see untapped potential for closer interactions. Macroecology is probably the discipline that most easily combines different time scales and where co‐operations between palaeoecologists, geneticists and vegetation modellers have been inspiring. Quantitative vegetation reconstructions provide robust estimates of tree composition and land cover at different spatial scales, suitable for testing hypotheses about long‐term vegetation changes or as quantitative background data in studies on contemporary vegetation patterns. Palaeo data also hold yet unexplored potential to study the drivers of long‐term diversity, and aspects of functional diversity may facilitate comparisons between continents and over glacial–interglacial cycles.