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Eukaryotic chromosome segregation requires a protein complex known as the kinetochore that mediates attachment between mitotic spindle microtubules and centromere-specific nucleosomes composed of the widely conserved histone variant CENP-A. Mutations in kinetochore proteins of the fission yeast Schizosaccharomyces pombe lead to chromosome missegregation such that daughter cells emerge from mitosis with unequal DNA content. We find that multiple copies of Msc1--a fission yeast homolog of the KDM5 family of proteins--suppresses the temperature-sensitive growth defect of several kinetochore mutants, including mis16 and mis18, as well as mis6, mis15, and mis17, components of the Constitutive Centromere Associated Network (CCAN). On the other hand, deletion of msc1 exacerbates both the growth defect and chromosome missegregation phenotype of each of these mutants. The C-terminal PHD domains of Msc1, previously shown to associate with a histone deacetylase activity, are necessary for Msc1 function when kinetochore mutants are compromised. We also demonstrate that, in the absence of Msc1, the frequency of localization to the kinetochore of Mis16 and Mis15 is altered from wild-type cells. As we show here for msc1, others have shown that elevating cnp1 levels acts similarly to promote survival of the CCAN mutants. The rescue of mis15 and mis17 by cnp1 is, however, independent of msc1. Thus, Msc1 appears to contribute to the chromatin environment at the centromere: the absence of Msc1 sensitizes cells to perturbations in kinetochore function, while elevating Msc1 overcomes loss of function of critical components of the kinetochore and centromere. [ABSTRACT FROM AUTHOR]

The coastal zone is a densely populated area with faster rates of economic growth, which plays an extremely important role in promoting national economic development. Under the background of global warming, the rise of sea level and increasing intensification of human activities are becoming a serious threat to human welfare in the coastal zone with a relatively fragile ecological environment. The study of transgressive sequence during glacial-interglacial cycles can improve our understanding of sea-level rise and variability under present and future continuing global warming. However, due to the limitation of early experimental condition and dating technique, the occurrence time of transgressions mostly lacks absolute age constraints since the late Middle Pleistocene in the eastern coastal region of China. As a result, there is still debate about the degree of occurring at different climatic periods, which limits the understanding of the formation and evolution mechanism of transgressive strata. In this study, a core (JH, 125 m thick) from the south wing of the Yangtze River Delta was investigated, which formed since the late Middle Pleistocene. Twelve samples were collected. Single-aliquot and single-grain optically stimulated luminescence (OSL) dating techniques have been carried out in determining quartz and feldspar samples with different grain size fractions (45-63 ìm, 90-125 ìm, 125-180 ìm, 180-250 ìm). Preliminary dating results show that the same sample with different grain size fractions or different samples with the same grain size fractions have different characteristics of the quartz or feldspar OSL signals, also showing significant age differences. The data is under further testing and analysis. The current results indicate that the upper 22 m of the core are Holocene deposits, and the lower part to 125 m is late Middle Pleistocene (~200 ka) deposits. Meanwhile, combining chronology with geochemistry, environmental magnetic and stratigraphy will be used to reveal evolutionary history of transgressiveregressive sequences, as well as on how to respond to global sea-level changes and paleotopographic variations in the southern wing of the Yangtze River Delta. [ABSTRACT FROM AUTHOR]

Since late 2017, the Luminescence Laboratory at the Indiana Geological and Water Survey has measured about 110 samples from Middle and Late Pleistocene (MIS6 to MIS2) glaciofluvial sediments in Indiana. The extensive dataset has allowed documentation of changes in luminescence properties across time and space in this ice-marginal setting, and to hypothesize sources for this variability. Exposed sections and cored sequences were sampled along margins of the Laurentide Ice Sheet (LIS) in Indiana. For MIS2 sediments, we differentiated between samples from the Lake Michigan Lobe (LML) sourced from the north, and the Huron-Erie Lobe (HEL), from the northeast. Small aliquots of 180-225 micron quartz and feldspar were used, each with 10-20 grains (maximum of 60), mounted on discs. Most of the quartz from MIS2 HEL sediment sequences displays low sensitivity. This is consistent with the relatively high (50%) proportion of aliquots displaying near-background signal and supports the idea that data from small aliquots is a proxy for single-grain measurement data. MIS2 LML samples display higher sensitivity. Dose recovery and preheat plateau tests for all MIS2 samples indicate that relatively lower preheat temperatures adequately recover given and unknown doses. A slow component detected in many of the aliquots analyzed did not affect SAR analysis performed with late-light background subtraction. High overdispersion was observed in both glaciofluvial and aeolian samples. Partial bleaching obscured data analysis in the proximal glaciofluvial samples. Minimum age models (MAM) were able to recover known ages within the range established by other dating methods with ~30-40 accepted aliquots in most cases. In some samples, however, even when the MAM was used in larger datasets, ages consistent with the stratigraphy were not resolved. MIS6 samples display higher sensitivity than MIS2 samples, and quartz ages range from 150 to 130 ka. A key factor in obtaining these ages is the relatively high level at which dose saturation appears for quartz in some subsurface samples in central Indiana. 2D0 values between 200 and 600 Gy help constrain the age of MIS6 sediments given the relatively low (1-2 Gy/ka) dose rates in most sediment packages. The 2D0 values are higher than values observed on MIS2 sediments from the same region. The difference in sensitivity and 2D0 values are hypothesized to be linked to different provenance lithologies, which is consistent with the geomorphological and geological data available. The similarity between high sensitivity quartz in MIS6 deposits and quartz derived from local Carboniferous sandstones in south-central Indiana suggests that a substantial region glaciated during MIS6 was never glaciated before, which is consistent with up to 60 m thick MIS6 glacifluvial sediment packages directly over the Carboniferous bedrock. This has implications in landscape evolution, paleoclimate and ice sheet modeling. When tested against quartz ages, post-IR IRSL protocols in feldspar appear to recover burial doses well, and potentially could extend the reach of the technique to ~250 ka. We conclude that both quartz and feldspar luminescence techniques can be applied successfully to sediments in this environment and age range, with the caveats discussed above. [ABSTRACT FROM AUTHOR]

OSL and IRSL dating are applied to samples from a 152 m-long drill core to constrain the timing of three glaciolacustrine depositional periods within the infill of an overdeepened bedrock trough in the Lower Glatt valley, N Switzerland. The characterisation of the dose-response suggests that the polymineral IRSL 50 and pIRIR 180/225 signals are close to saturation, while quartz OSL ages are within the range of reliable dating. The demarcation of the upper quartz OSL dating limit, however, remains challenging. Dose-recovery tests performed with long storage periods were used to investigate the reliability of the high region of the dose-response curve. They suggest an upper limit for reliable dating of ∼400 Gy for these samples, which was considerably lower than the commonly used 2 D 0 criterion. Lifetimes were calculated for the quartz OSL and the thermal stability of the signal is not considered as problematic for the determined ages. Allowing for a contribution from inherited dose due to partial bleaching, places the infill of the overdeepened valley within the penultimate glacial cycle (MIS6). [ABSTRACT FROM AUTHOR]

The study of planktic and benthic δ18O at site U1389 in the Gulf of Cadiz allowed us to reconstruct climate variability during the penultimate glacial period at an unprecedented millennial scale resolution. Hereby, a sequence of interstadial-stadial episodes similar to the Dansgaard-Oeschger events recorded during Marine Isotope Stage (MIS)3, were recognized in MIS6. After a detailed correlation with millennial-scale variability recorded along the Iberian margin and the North Atlantic we were able to link the millennial changes next to the Iberian Peninsula with Antarctic climate variability due to the interhemispheric seesaw response of the Atlantic circulation. The straight coupling at site U1389 of a) the planktic δ18O that reflects climate change in the Atlantic with b) the benthic δ18O, which records the temperature and oxygen isotope composition of the mixture of Mediterranean Outflow and Atlantic intermediate water, indicates that millennial climate variability also had a strong impact on the eastern Mediterranean. The detailed analysis of the benthic δ13C and the fine sand content in the sediments from site U1389 led us to recognize the response of the Mediterranean overflow water (MOW) to millennial scale changes in Mediterranean overturning circulation during the penultimate glaciation. Both Mediterranean Overturning Circulation and MOW strength increased at times of cool and arid climates and weakened during warm and more humid episodes, similar to what has been described for MIS3. The tuning of MOW weakening events occurring at times of precession minima with eastern Mediterranean sapropels and enhanced Asian monsoon allowed the elaboration of a new chronology for MIS6. It was compared with the Epica Dome C time scale, which was also based on the tuning of atmospheric δ18O with Asian Monsoons speleothem records. Mediterranean overturning during MIS6 was also strongly affected by freshwater perturbations occurring at times of insolation maxima, leading to the formation of the "glacial sapropel" S6. Two major drops in seawater δ18O centered at 175 and 150 ky were observed near the entrance of the Mediterranean that were related to meltwater released from the ice sheets, coinciding with periods of insolation maxima. The entry of this meltwater anomaly through the Strait of Gibraltar is clearly registered in the western and eastern Mediterranean, especially at the onset of sapropel S6, suggesting that it was a major component of the freshwater that initiated the buoyancy gain preceding deep water stagnation. • Stadial/interstadial episodes were observed in MIS6 similar to Dansgaard-Oeschger events. • Mediterranean overflow revealed millennial climate change in the Mediterranean in MIS6. • Meltwater from Ice Sheets contributed to Mediterranean stagnation during "glacial sapropels". [ABSTRACT FROM AUTHOR]

The article contains detailed petrographic studies, which covered a coarse and medium-grain gravel fraction of two layers of glacial till (units ŁS II and ŁS IV) and two layers of sand-gravelly outwash deposits (units ŁS I and ŁS III) related to the Odranian Glaciation (MIS6, Saalian) in Łubienica-Superunki, North Mazovian Lowland, central Poland. Additionally, the indicator erratics were identified to indicate their Scandinavian source areas and the directions of the ice sheet transgressions. This case study is discussed against the background of similar sediments and forms from the same age but from other places in the Polish Lowlands. Regardless of the facies types and fractions, crystalline rocks dominated over all other petrographic groups in all samples. The most common were the indicator erratics derived from the Åland Islands, followed by those from the south-eastern area of Sweden (Småland) and from Dalarna in central Sweden. Amongst the erratics of limited indicative significance, the most common were Lower Palaeozoic limestones and the Jotnian red sandstones. The complex petrographic analyses point to the dipartite nature of the studied profile. This separateness was confirmed by the TBC: 59.1–59.2° N and 18.0–18.2° E for the lower units and 58.8–59.4° N and 17.3–17.9° E for the upper ones. [ABSTRACT FROM AUTHOR]