Postglacial history of vegetation,human activity and lake-level changes at Jezioro Linówek in northeast Poland,based on multi-proxy data

We present the postglacial history of vegetation, human activities and changes in lake level in the context of climate change in northeast Poland from ~14,000 cal. b.p. to the present day. The palaeoecological reconstruction is based on the results of high-resolution plant macrofossil analyses as well as records from pollen, Cladocera and radiocarbon dating. Climate fluctuations and human activity have caused many changes in vegetation development in Jezioro Linówek and in the vicinity of this lake. The Early Holocene warming that occurred at ~9500 b.c. caused an increase in Betula and the colonisation of Linówek by Potamogeton lucens, Nymphaea alba and Chara sp. At ~2300 b.c., climate cooling was accompanied by the spread of Picea abies and the appearance of Potamogeton alpinus and Nuphar pumila in the lake. The first traces of farming in the form of Cerealia pollen have been dated back to ~2100 b.c. The cultivation of Triticum began at ~250 b.c., Secale at ~a.d. 550, and Fagopyrum at ~a.d. 1720. The rapid increase in human activity at ~a.d. 1700 and the simultaneous loss of woodland is associated with the establishment of villages in the area and is expressed by the decline of tree curves. In Linówek, which was formed ~14,000 cal. b.p., three periods of high water level occurred (12000–9400, 7000–4000 and 1450 b.c.–a.d. 650), and two periods of low water level (9400–7100 and 3700–1700 b.c.). The changes of water level correspond well with other sites in central and northern Europe.     

Stomatal differentiation and abnormal stomata in hornworts

This light and electron microscope study reveals considerable uniformity in hornwort stomata morphology and density in contrast to common spatial and developmental abnormalities in tracheophytes and mosses. Stomata arise from a median longitudinal division of sporophyte epidermal cells morphologically indistinguishable from their neighbours apart from the retention of a single chloroplast whilst those in the other epidermal cells fragment. Chloroplast division and side-by-side repositioning of the two daughter chloroplasts determines the division plane in the stomatal mother cell. The nascent guard cells contain giant, starch-filled chloroplasts which subsequently divide and, post aperture opening, regain their spherical shape. Accumulation of wall material over the guard cells and of wax rodlets lining the pores follows opening. While the majority of stomata are bilaterally symmetrical those lining the dehiscence furrows display dextral and sinistral asymmetry due to differential expansion of the adjacent epidermal cells.

The ubiquity of open stomata suggests that these never close with the maturational wall changes rendering movement extremely unlikely. These structural limitations, a liquid-filled stage in the ontogeny of the intercellular spaces, and spores already at the tetrad stage when stomata open, suggest that their primary role is facilitating sporophyte desiccation leading to dehiscence and spore dispersal rather than gaseous exchange. Stomata ontogeny and very low densities, like those in Devonian fossils, suggest either ancient origins at a time when atmospheric carbon dioxide levels were much greater than today or a function other than gaseous exchange regulation. We found no evidence for stomatal homology between hornworts, mosses and tracheophytes.     

Primary Seronegative but Molecularly Evident Hepadnaviral Infection Engages Liver and Induces Hepatocarcinoma in the Woodchuck Model of Hepatitis B

Hepadnavirus at very low doses establishes in woodchucks asymptomatic, serologically undetectable but molecularly evident persistent infection. This primary occult infection (POI) preferentially engages the immune system and initiates virus-specific T cell response in the absence of antiviral antibody induction. The current study aimed to determine whether POI with time may culminate in serologically identifiable infection and hepatitis, and what are, if any, its pathological consequences. Juvenile woodchucks were intravenously injected with inocula containing 10 or 100 virions of woodchuck hepatitis virus (WHV) to induce POI and followed for life or up to 5.5 years thereafter. All 10 animals established molecularly detectable infection with virus DNA in serum (<100–200 copies/mL) and in circulating lymphoid cells, but serum WHV surface antigen and antibodies to WHV core antigen remained undetectable for life. By approximately 2.5–3.5 years post-infection, circulating virus transiently increased to 10³ copies/mL and virus replication became detectable in the livers, but serological markers of infection and biochemical or histological evidence of hepatitis remained undetectable. Nonetheless, typical hepatocellular carcinoma (HCC) developed in 2/10 animals. WHV DNA integration into hepatic and lymphatic system genomes was identified in 9/10 animals. Virus recovered from the liver virus-negative or virus-positive phases of POI displayed the wild-type sequence and transmitted infection to healthy woodchucks causing hepatitis and HCC. In summary, for the first time, our data demonstrate that an asymptomatic hepadnaviral persistence initiated by very small amounts of otherwise pathogenic virus, advancing in the absence of traditional serological markers of infection and hepatitis, coincides with virus DNA integration into the host''s hepatic and immune system genomes, retains liver pro-oncogenic potency and is capable of transmitting liver pathogenic infection. This emphasizes the role for primary occult hepatitis B virus infection in the development of seemingly cyptogenic HCC in seronegative but virus DNA reactive patients.     

Liquid perfluorochemical-supported hybrid cell culture system for proliferation of chondrocytes on fibrous polylactide scaffolds

CP5 bovine chondrocytes were cultured on biodegradable electrospun fibrous polylactide (PLA) scaffolds placed on a flexible interface formed between two immiscible liquid phases: (1) hydrophobic perfluorochemical (PFC) and (2) aqueous culture medium, as a new way of cartilage implant development. Robust and intensive growth of CP5 cells was achieved in our hybrid liquid–solid–liquid culture system consisting of the fibrous PLA scaffolds in contrast to limited growth of the CP5 cells in traditional culture system with PLA scaffold placed on solid surface. The multicellular aggregates of CP5 cells covered the surface of PLA scaffolds and the chondrocytes migrated through and overgrew internal fibers of the scaffolds. Our hybrid culture system simultaneously allows the adhesion of adherent CP5 cells to fibers of PLA scaffolds as well as, due to use of phase of PFC, enhances the mass transfer in the case of supplying/removing of respiratory gases, i.e., O₂ and CO₂. Our flexible (independent of vessel shape) system is simple, ready-to-use and may utilize a variety of polymer-based scaffolds traditionally proposed for implant development.     

Mapping quantitative trait loci affecting some carcass and meat traits in duck (Anas platyrhynchos)

Contrary to chicken and livestock mammals, duck genome has not been explored much. Nowadays a relatively small number of reports on molecular variability and mapping of loci in Peking ducks has been published. Therefore, the objective of this study was to detect single loci affecting body weight, carcass and meat traits in Peking ducks (Anas platyrhynchos). The study was based on an F2 cross between two parental lines A-55 and GL-30. Phenotypes of 387 birds from generation F2 including carcass and meat quality traits were collected. Linkage map, of the linkage group CAU1, consisting of 29 microsatellite markers was constructed. One highly significant (p?p?相似文献   

General assessment of copy number variation in normal and tumor tissues of the domestic dog (Canis lupus familiaris)

In recent years, characterization of a copy number variation (CNV) of the genomic DNA has provided evidence for the relationship of this type of genetic variation with the occurrence of a broad spectrum of diseases, including cancer lesions. Copy number variants (CNVs) also occur in the genomes of healthy individuals as a result of abnormal recombination processes in germ cells and have a hereditary character contributing to the natural genetic diversity. Recent image analysis methods and advanced computational techniques allow for identification of CNVs using SNPs genotyping microarrays based on the analysis of signal intensity observed for markers located in the specific genomic regions. In this study we used CanineHD BeadChip assay (Illumina) to identify both natural and cancer-induced CNVs in the genomes of different dog breeds and in different cancer types occurring in this species. The obtained results showed that structural aberrations are a common phenomenon arising during a tumor progression and are more complex and widespread in tumors of mesenchymal tissue origin than in epithelial tissue originating tumors. The tumor derived CNVs, in comparison to healthy samples, were characterized by larger sizes of regions, higher number of amplifications, and in some cases encompassed genes with potential effect on tumor progression.     

Ordering effects of cholesterol and its analogues

Without any exaggeration, cholesterol is one of the most important lipid species in eukaryotic cells. Its effects on cellular membranes and functions range from purely mechanistic to complex metabolic ones, besides which it is also a precursor of the sex hormones (steroids) and several vitamins. In this review, we discuss the biophysical effects of cholesterol on the lipid bilayer, in particular the ordering and condensing effects, concentrating on the molecular level or inter-atomic interactions perspective, starting from two-component systems and proceeding to many-component ones e.g., modeling lipid rafts. Particular attention is paid to the roles of the methyl groups in the cholesterol ring system, and their possible biological function. Although our main research methodology is computer modeling, in this review we make extensive comparisons between experiments and different modeling approaches.     

Ordering effects of cholesterol and its analogues

Without any exaggeration, cholesterol is one of the most important lipid species in eukaryotic cells. Its effects on cellular membranes and functions range from purely mechanistic to complex metabolic ones, besides which it is also a precursor of the sex hormones (steroids) and several vitamins. In this review, we discuss the biophysical effects of cholesterol on the lipid bilayer, in particular the ordering and condensing effects, concentrating on the molecular level or inter-atomic interactions perspective, starting from two-component systems and proceeding to many-component ones e.g., modeling lipid rafts. Particular attention is paid to the roles of the methyl groups in the cholesterol ring system, and their possible biological function. Although our main research methodology is computer modeling, in this review we make extensive comparisons between experiments and different modeling approaches.     

The Role of the Antioxidant Enzymes in Erythrocytes in the Development of Arterial Hypertension among Humans Exposed to Lead

The study population included employees of metal works, with significant exposure to lead (Pb) for about 20 years (mean blood lead level PbB = 43 μg/dl), divided into four groups: normotensive (Pb-normotensive), high-normotensive, first (HT-1), and second degree (HT-2) of hypertension. The control group comprised of 30 office workers with normal blood pressure and no history of occupational exposure to lead. In erythrocytes, the activity of antioxidant enzymes and lipid peroxidation (measured as concentration of malondialdehyde (MDA)) was estimated. MDA concentration, glutathione peroxide (GPx), and superoxide dimutase (SOD) activities were significantly higher in Pb-normotensive group when compared to the normotensive control. Body mass index, age, duration of exposure to lead, and PbB were higher in both hypertensive groups than in Pb-normotensive or high-normotensive groups. MDA increased in HT-1 group by 48% and in HT-2 by 72%, and the activity of GPx decreased significantly in HT-1 group, by 30% and in HT-2 by 43%. No significant differences were observed in their activity of SOD, catalase, and glutathione reductase in erythrocytes. Arterial blood pressure (both systolic and diastolic) positively correlated with body mass index (BMI), age, lead exposure duration, PbB, MDA, and negatively correlated with GPx. There was no significant correlation between BMI and MDA, BMI and GPx, age and MDA, AND age and GPx. In conclusion: (1) lead increases erythrocyte MDA concentration and the activity of GPx as well as SOD in normotensive subjects. (2) Among individuals exposed to lead, with arterial hypertension diagnosed, higher body mass index, age, values of blood lead level, and prolonged exposure to lead have been noticed, accompanied by intensified oxidative stress and the decrease in the activity of glutathione peroxidase in erythrocytes. The reasons for increase of blood pressure in lead exposure remain unrecognized.