Subfossil chydorid (Cladocera, Chydoridae) ephippia as paleoenvironmental proxies: evidence from boreal and subarctic lakes in Finland

Chydorids (Cladocera, Chydoridae) have two reproductive strategies: asexual reproduction that prevails during favorable environmental conditions and sexual reproduction that is induced by environmental stimuli associated with seasonal or aperiodic environmental stresses. These modes of reproduction can be recognized in the subfossil sedimentary records as parthenogenetic shells of females (asexual reproduction) and by ephippia (sexual reproduction). We studied the interrelations between subfossil chydorid ephippia and environmental variables by analyzing surface sediment samples obtained from 76 Finnish lakes across a latitudinal gradient (60–70°N). The results showed that the total chydorid ephippia (TCE) increases along the climate gradient from ~2 to 3% in the south to ~25% in the north and suggested a significant dependence (r ~ −0.8, P < 0.001) with several climate factors, especially that of mean July air temperature. We used this relationship to create a model for reconstructing past mean July air temperatures. A linear regression of the log₁₀ transformed TCE as a single independent variable explained 76% (SE ± 0.76°C) of the variance of the observed mean July air temperatures. Accordingly, we propose that this novel tool may be highly suitable for reconstructing paleotemperatures in cold-temperate environments.     

Prevalence, genotype distribution and persistence of human papillomavirus in oral mucosa of women: a six-year follow-up study

Background

Human papillomavirus (HPV) infections have been linked to a subset of oral and oropharyngeal cancers. However, little is known on the natural history of oral HPV infections. We designed the prospective Finnish HPV Family Study to assess the dynamics of HPV infections in parents and their infants. This study reports HPV genotype distribution and virus persistence in oral mucosa of the mothers.

Materials and Methods

Totally, 324 pregnant women were enrolled at the 3^rd trimester of pregnancy and followed-up for 6 years. Oral scrapings taken with a brush were collected and HPV-genotyping was performed with nested PCR and Multimetrix® test (Progen, Heidelberg, Germany). The predictors of persistent oral HPV species 7/9 infections were analyzed using generalized estimating equation models.

Results

The point prevalence of oral HPV varied from 15% to 24% during the 6-year follow-up. Altogether, 18 HPV genotypes were identified either as single or multiple-type oral infections. HPV16 was the most prevalent type at 9.7%–18.4%, followed by HPV18, HPV6, and multiple infections. Altogether, 74 women had persistent oral HPV infection determined as at least two consecutive samples positive with the same HPV genotype. HPV16 and HPV6 were the two most frequent types to persist (76% and 9%) for a mean of 18.6 and 20.2 months, respectively, followed by multiple infections (8%) for 18.3 months. An increased risk for persistent oral HPV infection with species 7/9 was associated with being seropositive for low-risk (LR)-HPV-types at baseline, whereas the use of oral contraceptives and a second pregnancy during follow-up were protective. Clinical oral lesions were detected in 17% of these women, one-third of whom had persistent oral HPV-infections.

Conclusion

HPV16 and HPV6 were the most common genotypes in oral HPV-infections and were also most likely to persist. Use of oral contraceptives and a second pregnancy protected against oral HPV persistence.     

Structural characteristics and chemical composition of birch (Betula pendula) leaves are modified by increasing CO2 and ozone

Impacts of ozone and CO₂ enrichment, alone and in combination, on leaf anatomical and ultrastructural characteristics, nutrient status and cell wall chemistry in two European silver birch (Betula pendula Roth) clones were studied. The young soil‐growing trees were exposed in open‐top chambers over three growing seasons to 2 × ambient CO₂ and/or ozone concentrations in central Finland. The trees were measured for changes in altogether 35 variables of leaf structure, nutrients and cell wall chemistry of green leaves, and 20 of the measured variables were affected by CO₂ and/or O₃. Elevated CO₂ increased the size of chloroplasts and starch grains, number of mitochondria, P : N ratio, and contents of cell wall hemicellulose. Elevated CO₂ decreased the total leaf thickness, specific leaf area, concentrations of N, K, Cu, S and Fe, and contents of cell wall α‐cellulose, uronic acids, acid‐soluble lignin and acetone‐soluble extractives. Elevated ozone led to thinner leaves, higher palisade to spongy ratio, increased number of peroxisomes and mitochondria, reduced content of Mn, Zn, Cu, hemicellulose and uronic acids, and lower Mn : N and Zn : N ratios. In the combined exposure, interactions were antagonistic. Ultrastructural changes became more evident towards the end of the exposure. Young leaves were tolerant against ozone‐caused oxidative stress, whereas oxidative H₂O₂ accumulation was found in older leaves. CO₂ enrichment improved ozone tolerance not only through increased photosynthesis rates, but also through changes in cell wall chemistry (hemicellulose, in particular). However, nutrient imbalances due to ozone and/or CO₂ may predispose the trees to other biotic and abiotic stresses. Down‐regulation and up‐regulation of photosynthesis under elevated CO₂ through anatomical changes is discussed.     

Microdomains of endoplasmic reticulum within the sarcoplasmic reticulum of skeletal myofibers

The relationship between the endoplasmic reticulum (ER) and the sarcoplasmic reticulum (SR) of skeletal muscle cells has remained obscure. In this study, we found that ER- and SR-specific membrane proteins exhibited diverse solubility properties when extracted with mild detergents. Accordingly, the major SR-specific protein Ca(2+)-ATPase (SERCA) remained insoluble in Brij 58 and floated in sucrose gradients while typical ER proteins were partially or fully soluble. Sphingomyelinase treatment rendered SERCA soluble in Brij 58. Immunofluorescence staining for resident ER proteins revealed dispersed dots over I bands contrasting the continuous staining pattern of SERCA. Infection of isolated myofibers with enveloped viruses indicated that interfibrillar protein synthesis occurred. Furthermore, we found that GFP-tagged Dad1, able to incorporate into the oligosaccharyltransferase complex, showed the dot-like structures but the fusion protein was also present in membranes over the Z lines. This behaviour mimics that of cargo proteins that accumulated over the Z lines when blocked in the ER. Taken together, the results suggest that resident ER proteins comprised Brij 58-soluble microdomains within the insoluble SR membrane. After synthesis and folding in the ER-microdomains, cargo proteins and non-incorporated GFP-Dad1 diffused into the Z line-flanking compartment which likely represents the ER exit sites.     

中国晚中新世陆相哺乳动物群序列:陕西蓝田的新证据(英文)

自 2 0世纪 60年代 ,陕西蓝田地区就以连续的晚新生代地层及丰富的哺乳动物化石而成为研究中国晚新生代哺乳动物与地层划分对比的经典地区之一。李传夔等 ( 1 984)根据灞河组发现的哺乳动物化石建立了灞河期 ,并与欧洲的Vallesian期对比。邱占祥等( 1 990 ,1 995)认为化石证据不充分 ,而将其与保德期合并。近年来 ,黄土高原三趾马红粘土大量的年代学资料表明 ,红粘土沉积最早可能开始于约 8Ma前。因此 ,狭义的保德期可能只代表了晚中新世晚期 ,晚中新世哺乳动物分期的再划分问题又重新被提出。自 1 997年以来 ,我们课题组在蓝田地区共发现 52个化石地点 ,其中的 2 6个含有哺乳动物化石 ,大哺乳动物化石标本共计 1 666件。经过详细野外地层测量 ,绘制了综合地层剖面 ,并将主要含哺乳动物化石的地点对比标定到综合地层剖面上。经过对各门类化石的初步研究 ,以及对已有化石材料的初步修订 ,到目前为止 ,陕西蓝田灞河组共计发现哺乳动物化石 45种 ,蓝田组 2 0种。新的化石证据表明 ,灞河组发现的哺乳动物化石组合完全不同于典型意义上的保德三趾马动物群。大哺乳动物化石以灞河三趾马与贾氏三趾马为代表 ,牛科化石组合在种级甚至属级上有明显的区别。大量的陕西转角羚羊 ,小型的Protoryx、Dorcadoryx以及Ga     

Stem wood properties of Populus tremuloides, Betula papyrifera and Acer saccharum saplings after 3 years of treatments to elevated carbon dioxide and ozone

The aim of this study was to examine the effects of elevated carbon dioxide [CO₂] and ozone [O₃] and their interaction on wood chemistry and anatomy of five clones of 3‐year‐old trembling aspen (Populus tremuloides Michx.). Wood chemistry was studied also on paper birch (Betula papyrifera Marsh.) and sugar maple (Acer saccharum Marsh.) seedling‐origin saplings of the same age. Material for the study was collected from the Aspen Free‐Air CO₂ Enrichment (FACE) experiment in Rhinelander, WI, USA, where the saplings had been exposed to four treatments: control (C; ambient CO₂, ambient O₃), elevated CO₂ (560 ppm during daylight hours), elevated O₃ (1.5 × ambient during daylight hours) and their combination (CO₂+O₃) for three growing seasons (1998–2000). Wood chemistry responses to the elevated CO₂ and O₃ treatments differed between species. Aspen was most responsive, while maple was the least responsive of the three tree species. Aspen genotype affected the responses of wood chemistry and, to some extent, wood structure to the treatments. The lignin concentration increased under elevated O₃ in four clones of aspen and in birch. However, elevated CO₂ ameliorated the effect. In two aspen clones, nitrogen in wood samples decreased under combined exposure to CO₂ and O₃. Soluble sugar concentration in one aspen clone and starch concentration in two clones were increased by elevated CO₂. In aspen wood, α‐cellulose concentration changed under elevated CO₂, decreasing under ambient O₃ and slightly increasing under elevated O₃. Hemicellulose concentration in birch was decreased by elevated CO₂ and increased by elevated O₃. In aspen, elevated O₃ induced statistically significant reductions in distance from the pith to the bark and vessel lumen diameter, as well as increased wall thickness and wall percentage, and in one clone, decreased fibre lumen diameter. Our results show that juvenile wood properties of broadleaves, depending on species and genotype, were altered by atmospheric gas concentrations predicted for the year 2050 and that CO₂ ameliorates some adverse effects of elevated O₃ on wood chemistry.     

Inactivation of mouse transmembrane prolyl 4-hydroxylase increases blood brain barrier permeability and ischemia-induced cerebral neuroinflammation

Hypoxia-inducible factor prolyl 4-hydroxylases (HIF-P4Hs) regulate the hypoxic induction of >300 genes required for survival and adaptation under oxygen deprivation. Inhibition of HIF-P4H-2 has been shown to be protective in focal cerebral ischemia rodent models, while that of HIF-P4H-1 has no effects and inactivation of HIF-P4H-3 has adverse effects. A transmembrane prolyl 4-hydroxylase (P4H-TM) is highly expressed in the brain and contributes to the regulation of HIF, but the outcome of its inhibition on stroke is yet unknown. To study this, we subjected WT and P4htm^−/− mice to permanent middle cerebral artery occlusion (pMCAO). Lack of P4H-TM had no effect on lesion size following pMCAO, but increased inflammatory microgliosis and neutrophil infiltration was observed in the P4htm^−/− cortex. Furthermore, both the permeability of blood brain barrier and ultrastructure of cerebral tight junctions were compromised in P4htm^−/− mice. At the molecular level, P4H-TM deficiency led to increased expression of proinflammatory genes and robust activation of protein kinases in the cortex, while expression of tight junction proteins and the neuroprotective growth factors erythropoietin and vascular endothelial growth factor was reduced. Our data provide the first evidence that P4H-TM inactivation has no protective effect on infarct size and increases inflammatory microgliosis and neutrophil infiltration in the cortex at early stage after pMCAO. When considering HIF-P4H inhibitors as potential therapeutics in stroke, the current data support that isoenzyme-selective inhibitors that do not target P4H-TM or HIF-P4H-3 would be preferred.     

The effects of a permanently elevated water table in an acid sulphate soil on reed canary grass for combustion

Aims and background

Acid sulphate (AS) soils require careful management to prevent the environmental hazards that result from the oxidation of sulphide-bearing deep soil layers and the consequent acidification of soil and waters. Management with a high water table precludes many food crops, so their suitability for perennial energy cropping was investigated in a 3-year study using reed canary grass (Phalaris arundinacea L., RCG).

Methods

Monolithic lysimeters made of undisturbed AS soil and equipped with ground-water level control and measurement instruments were planted with 1- year-old RCG turfs taken from a non-AS field. Two water tables were imposed, high (HWT, 20 cm below soil surface) and low (LWT, 70 cm below soil surface, considered normal for agriculturally managed AS soils) for a 3 year period. Growth and physiological characters of RCG were determined and its ash content and the elemental composition of its dry biomass (Ca, Cl, K, Mg, and S) were analysed.

Results

The level of the water table had significant effects on crop growth and quality. Shoots were 25 to 29 % taller, consequently yielding more dry matter in HWT than in LWT lysimeters. Concentrations of K, Mg and S that can affect the combustion process were higher in biomass harvested from LWT lysimeters than from the HWT plants. At the end of the experiment, the spatial distribution of roots within the soil profile differed between treatments. Roots penetrated to the bottom of LWT lysimeters with total root dry mass nearly twice that in HWT.

Conclusions

RCG intended for burning grows and performs well in acid sulphate soils managed with a raised water table. This management option minimizes the risk of acid flows from oxidized soils, and allows farmers to harvest a non-food crop from soils that would have to be drained to provide a food or feed crop.     

Deletion of the gene encoding the ubiquitously expressed glucose-6-phosphatase catalytic subunit-related protein (UGRP)/glucose-6-phosphatase catalytic subunit-beta results in lowered plasma cholesterol and elevated glucagon

In liver, glucose-6-phosphatase catalyzes the hydrolysis of glucose-6-phosphate (G6P) to glucose and inorganic phosphate, the final step in the gluconeogenic and glycogenolytic pathways. Mutations in the glucose-6-phosphatase catalytic subunit (G6Pase) give rise to glycogen storage disease (GSD) type 1a, which is characterized in part by hypoglycemia, growth retardation, hypertriglyceridemia, hypercholesterolemia, and hepatic glycogen accumulation. Recently, a novel G6Pase isoform was identified, designated UGRP/G6Pase-beta. The activity of UGRP relative to G6Pase in vitro is disputed, raising the question as to whether G6P is a physiologically important substrate for this protein. To address this issue we have characterized the phenotype of UGRP knock-out mice. G6P hydrolytic activity was decreased by approximately 50% in homogenates of UGRP(-/-) mouse brain relative to wild type tissue, consistent with the ability of UGRP to hydrolyze G6P. In addition, female, but not male, UGRP(-/-) mice exhibit growth retardation as do G6Pase(-/-) mice and patients with GSD type 1a. However, in contrast to G6Pase(-/-) mice and patients with GSD type 1a, UGRP(-/-) mice exhibit no change in hepatic glycogen content, blood glucose, or triglyceride levels. Although UGRP(-/-) mice are not hypoglycemic, female UGRP(-/-) mice have elevated ( approximately 60%) plasma glucagon and reduced ( approximately 20%) plasma cholesterol. We hypothesize that the hyperglucagonemia prevents hypoglycemia and that the hypocholesterolemia is secondary to the hyperglucagonemia. As such, the phenotype of UGRP(-/-) mice is mild, indicating that G6Pase is the major glucose-6-phosphatase of physiological importance for glucose homeostasis in vivo.     

A mechanism for neurodegeneration induced by group B streptococci through activation of the TLR2/MyD88 pathway in microglia

Group B Streptococcus (GBS) is a major cause of bacterial meningitis and neurological morbidity in newborn infants. The cellular and molecular mechanisms by which this common organism causes CNS injury are unknown. We show that both heat-inactivated whole GBS and a secreted proteinaceous factor from GBS (GBS-F) induce neuronal apoptosis via the activation of murine microglia through a TLR2-dependent and MyD88-dependent pathway in vitro. Microglia, astrocytes, and oligodendrocytes, but not neurons, express TLR2. GBS as well as GBS-F induce the synthesis of NO in microglia derived from wild-type but not TLR2(-/-) or MyD88(-/-) mice. Neuronal death in neuronal cultures complemented with wild-type microglia is NO-dependent. We show for the first time a TLR-mediated mechanism of neuronal injury induced by a clinically relevant bacterium. This study demonstrates a causal molecular relationship between infection with GBS, activation of the innate immune system in the CNS through TLR2, and neurodegeneration. We suggest that this process contributes substantially to the serious morbidity associated with neonatal GBS meningitis and may provide a potential therapeutic target.