Експериментальне дослідження впливу сполук важких металів на систему згортання крові в умовах in vitro

В работе приведены результаты экспериментального исследования в условиях in vitro влияния тяжелых металловn(свинца, кадмия, ртути и марганца) на плазму крови и еекомоненты (белки). Влияние тяжелых металлов на коагулометрические характеристики плазмыкрови человека характеризовалось как гипокоагуляционное. Денатурирующие свойства солей тяжелых металлов изучались на белках системы свертывания крови (тромбопластин, фибриноген и тромбин). Металлы вызывали существенные конформационные изменения белков в последовательности Pb > Hg > Cd > Mn. Выявленные гипокоагуляционные изменения плазмы крови человека могут быть обусловлены влиянием тяжелых металлов на структуру и активность белков, участвующих в процессе свертывания крови.The article presents the results of in vitro studies of heavy metals exposure (lead, cadmium, mercury and mangan ese) on blood plasma and its components (proteins). The influence of heavy metals on coagulometric characteristics of blood plasma can be described as hypocoagulating. Denaturating properties of heavy metals was studied on blood coagulation proteins (thromboplastin, fibrinogen and thrombin). Metals caused significant conformation changes in proteins in the following order Pb > Hg > Cd > Mn. The revealed hypocoagulation changes in human plasma can be predetermined by heavy metals exposure on the structure and activity of proteins that take part in blood coagulation process

Columbus’ footprint in Hispaniola:A paleoenvironmental record of indigenous and colonial impacts on the landscape of the central Cibao Valley, northern Dominican Republic

The 1100-year sedimentary record of Laguna Biajaca reveals human-driven landscape changes in the central Cibao Valley, Dominican Republic, Hispaniola. This sediment-filled cutoff meander is located in close proximity to pre-Colonial archaeological sites and a Colonial urban hub. It provided a nutrient-rich floodable locus for agricultural activities for indigenous communities and for the first introduction of Old World crops and cattle in the Americas. Integration of paleoecological proxies revealed the formation of a clear-water body surrounded by a palm-rich forested landscape around 1100 cal yr BP. Changes in the drainage system were linked to human-driven deforestation, which also changed the composition of the vegetation and fungal communities around the site between AD 1150 and 1500 (800 and 700 cal yr BP). Pre-Colonial modifications of the landscape were primarily the result of fire-use and small-scale clearings. Crop cultivation developed between AD 1250 and 1450 (700–500 cal yr BP). Within decades after Columbus’ arrival in Hispaniola in AD 1492, the first impacts of European colonization included the abandonment of indigenous sites and the introduction of Old World domesticated animals. During the 15th and 16th centuries the area underwent intensive land-clearing that allowed for larger scale crop cultivation. An increase of aquatic vegetation points to sediment-filling around AD 1700 (250 cal yr BP). At that time, cattle breeding expanded and rapidly provoked eutrophication while, concurrently, monocultures became regionally established. This paper provides a framework of past environmental dynamics and offers an opportunity to place archaeological findings in a context of natural and anthropogenic change

Land–sea coupling of early Pleistocene glacial cycles in the southern North Sea exhibit dominant Northern Hemisphere forcing

We assess the disputed phase relations between forcing and climatic response in the early Pleistocene with a spliced Gelasian (∼ 2.6–1.8 Ma) multi-proxy record from the southern North Sea basin. The cored sections couple climate evolution on both land and sea during the intensification of Northern Hemisphere glaciation (NHG) in NW Europe, providing the first well-constrained stratigraphic sequence of the classic terrestrial Praetiglian stage. Terrestrial signals were derived from the Eridanos paleoriver, a major fluvial system that contributed a large amount of freshwater to the northeast Atlantic. Due to its latitudinal position, the Eridanos catchment was likely affected by early Pleistocene NHG, leading to intermittent shutdown and reactivation of river flow and sediment transport. Here we apply organic geochemistry, palynology, carbonate isotope geochemistry, and seismostratigraphy to document both vegetation changes in the Eridanos catchment and regional surface water conditions and relate them to early Pleistocene glacial–interglacial cycles and relative sea level changes. Paleomagnetic and palynological data provide a solid integrated timeframe that ties the obliquity cycles, expressed in the borehole geophysical logs, to Marine Isotope Stages (MIS) 103 to 92, independently confirmed by a local benthic oxygen isotope record. Marine and terrestrial palynological and organic geochemical records provide high-resolution reconstructions of relative terrestrial and sea surface temperature (TT and SST), vegetation, relative sea level, and coastal influence.During the prominent cold stages MIS 98 and 96, as well as 94, the record indicates increased non-arboreal vegetation, low SST and TT, and low relative sea level. During the warm stages MIS 99, 97, and 95 we infer increased stratification of the water column together with a higher percentage of arboreal vegetation, high SST, and relative sea level maxima. The early Pleistocene distinct warm–cold alterations are synchronous between land and sea, but lead the relative sea level change by 3000–8000 years. The record provides evidence for a dominantly Northern Hemisphere-driven cooling that leads the glacial buildup and varies on the obliquity timescale. Southward migration of Arctic surface water masses during glacials, indicated by cool-water dinoflagellate cyst assemblages, is furthermore relevant for the discussion on the relation between the intensity of the Atlantic meridional overturning circulation and ice sheet growth

Reconstruction of El Niño - Southern oscillation variability during the Holocene

The El Niño – Southern Oscillation (ENSO) in the tropical Pacific constitutes the largest source of global climate variability on interannual timescales. Every 2-7 year the El Niño phenomenon causes altered Pacific circulation, leading to widespread droughts and floods. However, the exact mechanisms are still poorly understood and especially the expected behavior of ENSO dynamics in a greenhouse world under increased radiative forcing is heavily debated. A detailed reconstruction of past ENSO activity can provide insight into the spatial and temporal climate variability caused by the ENSO system on centennial to millennial time scales and, at the same time, help assessing the potential role of changes in radiative forcing as driving mechanism for ENSO dynamics. Investigation of terrestrial systems is essential, since the impacts of ENSO are most prominent on land. Botanical proxy records are increasingly used for climate reconstructions since plants respond immediately to changes such as drought or precipitation surplus. Plant remains buried in peat and lake deposits provide the source material utilized in proxy-based climate reconstructions. In southern Florida wetlands, a strong well-documented ENSO teleconnection can be used for calibration of the botanical proxies. With improved AMS-radiocarbon chronologies it is shown that vegetation during the 20th century, reconstructed by pollen analysis, responded to both annual and decadal-scale changes in wetland hydrology. In addition, a new precipitation proxy based on the analysis of structural xeromorphic features in Quercus laurifolia leaves confims the pollen results. Furthermore, parallel stomatal frequency analysis performed on the fossil leaves reveals a distinct CO2 sensitivity of Q. laurifolia. Combined analysis of CO2 and drought stress signals provides a unique method to synchronously document changing ENSO-tied precipitation patterns and atmospheric CO2 concentrations beyond the period of instrumental measurements. Spectral analysis and bandpass filtering of the near-annually resolved botanical-proxy records from Florida reveals significant variability, which is highly comparable to the measured ENSO periodicity. These results show that the ENSO signature can be detected in non annually-laminated sediments and allow direct testing of past ENSO dynamics in high-accumulation sediment sequences. Pollen analyses of Holocene peat deposits from southwest Florida reveal a step-wise increase in wetland vegetation that points to an increased precipitation-driven fresh-water flow during the past 5, 000 years. The subtropical record documents ecosystem responsed to the onset of modern-day ENSO periodicities between ~7, 000 and 5, 000 years BP, known from tropical marine and terrestrial records, and subsequent ENSO intensification after 3, 500 years BP. These changes are confirmed by pollen analysis from eastern Australia, a region with strong ENSO teleconnections that are anti-correlated with the ENSO impacts in Florida. At a highly precipitation-sensitive site in subtropical Queensland the vegetation strongly diversified into heterogeneous subtropical rainforest after 3 cal ky BP. These results are incorporated into a review of Holocene climate patterns in eastern Australia along a North-to-South transect. Early Holocene changes are divergent and asynchronous between sites, while middle to late Holocene conditions are characterized by a more synchronous change to arid and variable conditions. Based on the present-day Australian climate patterns and impact of ENSO, these results are in agreement with ENSO intensification. Finally, an integrated overview of marine and terrestrial paleoclimatic data relevant to the detection of ENSO variability is presented. Analysis of proxy climate data indicate that, after a climate-state change at ~5 ky BP towards active ENSO cyclicity in the equatorial Pacific, ENSO-teleconnected regions are characterized by an increased amplitude of ENSO events only around 3 ky BP. Comparison with climate model scenarios shows that the generally accepted view that ENSO intensification results from summer Pacific trade wind reduction cannot completely explain the observed Holocene changes. An additional mechanism is proposed, involving increased Indo-Pacific Warm Pool (IPWP) heat charging, which could have resulted in a 3 ky BP increase of ENSO amplitude

Drought stress signals in modern and subfossil Quercus laurifolia (Fagaceae) leaves reflect winter precipitation in southern Florida tied to El Niño-Southern Oscillation activity

In the present study, structural xeromorphic features in modern and subfossil Quercus laurifolia leaves from southern Florida were quantified to reconstruct past precipitation changes in sensitive terrestrial settings. Absolute cell numbers/mm2, quantified as epidermal cell density (ED) have been analyzed on leaves from herbarium collections as well as the leaves accumulated during the past 125 years in peat deposits. The results reveal a common principal correlation between the measured ED and winter precipitation (November through March, NDJFM: Herbarium r = - 0.74; peat profiles FAK98 r = - 0.72, FAK02 r = - 0.53) providing a measure of seasonal drought stress. In Florida, the amount of winter precipitation depends on El Niñ o-Southern Oscillation (ENSO) activity, where El Niñ o years produce wet and cold winters, while La Niñ a winters are dry and warm. The negative correlation between cell numbers and winter precipitation has the potential to record precipitation variability from subfossil leaves on near-annual to decadal time scales. In subtropical, terrestrial environments, where traditional paleo-proxies are limited, systematic analysis of leaf morphological characteristics can provide important information on precipitation changes through time. © 2010 Botanical Society of America