bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in nitrogen cycling and retention processes in soils under spruce forests along a nitrogen enrichment gradient in Germany
Authors: CORRE MARIFE D. , BRUMME RAINER , VELDKAMP EDZO , BEESE FRIEDRICH O. 
Published: June 2007

AbstractA network of long‐term monitoring sites on nitrogen (N) input and output of forests across Germany showed that a number of Germany's forests are subject to or are experiencing N saturation and that spruce (Picea abies) stands have high risk. Our study was aimed at (1) quantifying the changes in gross rates of microbial N cycling and retention processes in forest soils along an N enrichment gradient and (2) relating the changes in soil N dynamics to N losses. We selected spruce sites representing an N enrichment gradient (indicated by leaching : throughfall N ratios) ranging from 0.04–0.13 (low N),≤0.26 (intermediate N enrichment) to≥0.42 (highly N enriched). To our knowledge, our study is the first to report on mechanistic changes in gross rates of soil N cycling and abiotic NO3− retention under ambient N enrichment gradient. Gross N mineralization, NH4+ immobilization, gross nitrification, and NO3− immobilization rates increased up to intermediate N enrichment level and somewhat decreased at highly N‐enriched condition. The turnover rates of NH4+ and microbial N pools increased while the turnover rates of the NO3− pool decreased across the N enrichment gradient. Abiotic immobilization of NH4+ did not differ across sites and was lower than that of NO3−. Abiotic NO3− immobilization decreased across the N enrichment gradient. Microbial assimilation and turnover appeared to contribute largely to the retention of NH4+. The increasing NO3− deposition and decreasing turnover rates of the NO3− pool, combined with decreasing abiotic NO3− retention, possibly contributed to increasing NO3− leaching and gaseous emissions across the N enrichment gradient. The empirical relationships of changes in microbial N cycling across the N enrichment gradient may be integrated in models used to predict responses of forest ecosystems (e.g. spruce) to increasing N deposition.
Taxonomic and biological trait differences of stream macroinvertebrate communities between mediterranean and temperate regions: implications for future climatic scenarios
Authors: BONADA NÚRIA , DOLÉDEC SYLVAIN , STATZNER BERNHARD 
Published: June 2007

AbstractStreams in mediterranean regions have highly seasonal discharge patterns, with predictable torrential floods and severe droughts. In contrast, discharge is less variable in temperate regions and intermittent flow conditions are uncommon. Hydroclimatic models predict that climate change would increase frequency and severity of floods and droughts across Europe, thus increasing the proportion of streams with mediterranean characteristics in actually temperate areas. Correspondingly, understanding actual ecological differences between mediterranean and temperate streams may help to anticipate large‐scale ecological impacts of climate change. Given that large‐scale factors determine local community composition, we hypothesized that climatic differences between mediterranean and temperate regions should affect the taxonomic and biological trait composition in streams. We assembled the abundance of stream macroinvertebrate genera of 265 sites each from the Mediterranean Basin and from temperate Europe and linked these abundances to published information on 61 categories of 11 biological traits reflecting the potential of resilience from and resistance to disturbances. Although regional taxonomic richness was higher in the mediterranean than in the temperate region, local taxonomic richness and diversity did not significantly differ between regions. Local trait richness and diversity were significantly higher in the mediterranean region. Both local taxonomic and trait‐community composition differed between regions, but the former varied much more than the latter, highlighting that climate change could produce large changes in the taxonomic but rather weak changes in the trait composition. The mediterranean region was characterized by macroinvertebrates with higher dispersion and colonization capabilities, suggesting that species loss in the temperate region, by extinction or northward emigration of taxa, would be compensated for by immigration of southern mediterranean taxa. Thus, climate change would likely have stronger implications for the local conservation of taxa than for the trait composition of stream macroinvertebrate communities.
Genetic maladaptation of coastal Douglas‐fir seedlings to future climates
Authors: BRADLEY ST CLAIR J. , HOWE GLENN T. 
Published: June 2007

AbstractClimates are expected to warm considerably over the next century, resulting in expectations that plant populations will not be adapted to future climates. We estimated the risk of maladaptation of current populations of coastal Douglas‐fir (Pseudotsuga menziesiivar.menziesii) to future climates as the proportion of nonoverlap between two normal distributions where the means and genetic variances of current and future populations are determined from genecological models derived from seedling common garden studies. The risk of maladaptation was large for most traits when compared with the risk associated with current transfers within seed zones, particularly for the more drastic climate change scenario. For example, the proportion of nonoverlap for a composite trait representing bud set, emergence, growth, and root : shoot ratio was as high as 0.90. We recommend augmenting within‐population variation by mixing local populations with some proportion of populations from lower elevations and further south. Populations expected to be adapted to climates a century from now come from locations as far down in elevation as 450–1130 m and as far south in latitude as 1.8–4.9°.
Potential effects of interaction between CO2and temperature on forest landscape response to global warming
Authors: XU CHONGGANG , GERTNER GEORGE Z. , SCHELLER ROBERT M. 
Published: June 2007

AbstractProjected temperature increases under global warming could benefit southern tree species by providing them the optimal growing temperature and could be detrimental to northern species by exposing them to the supra optimal growing temperatures. This benefit‐detriment trade‐off could increase the competitive advantage of southern species in the northern species range and cause the increase or even dominance of southern species in the northern domain. However, the optimum temperature for photosynthesis of C3 plants may increase due to CO2enrichment. An increase in the optimum temperature could greatly reduce the benefit‐detriment effect. In this study, we coupled a forest ecosystem process model (PnET‐II) and a forest GAP model (LINKAGES) with a spatially dynamic forest landscape model (LANDIS‐II) to study how an optimum temperature increase could affect forest landscape response due to global warming. We simulated 360 years of forest landscape change in the Boundary Water Canoe Area (BWCA) in northern Minnesota, which is transitional between boreal and temperate forest. Our results showed that, under the control scenario of continuing the historic 1984–1993 mean climate (mainly temperature, precipitation and CO2), the BWCA will become a spruce‐fir dominated boreal forest. However, under the scenario of predicted climatic change [the 2000–2099 climates are predicted by Canadian Climate Center (CCC), followed by 200 years of continuing the predicted 2090–2099 mean climate], the BWCA will become a pine‐dominated mixed forest. If the optimum temperature increases gradually with [CO2] (the increase in optimum temperature is assumed to change gradually from 0 °C in year 2000 to 5 °C in year 2099 when [CO2] reaches 711 ppm and stabilizes at 5 °C after year 2099), the BWCA would remain a fir‐dominated boreal forest in areas with relatively high water‐holding capacity, but not in areas with relatively low water‐holding capacity. Our results suggest that the [CO2] induced increases in optimum temperature could substantially reduce forest landscape change caused by global warming. However, not all tree species would be able to successfully adapt to future warming as predicted by CCC, regardless of optimum temperature acclimations.
Nitrite‐driven nitrous oxide production under aerobic soil conditions: kinetics and biochemical controls
Authors: VENTEREA RODNEY T. 
Published: June 2007

AbstractNitrite (NO2−) can accumulate during nitrification in soil following fertilizer application. While the role of NO2− as a substrate regulating nitrous oxide (N2O) production is recognized, kinetic data are not available that allow for estimating N2O production or soil‐to‐atmosphere fluxes as a function of NO2− levels under aerobic conditions. The current study investigated these kinetics as influenced by soil physical and biochemical factors in soils from cultivated and uncultivated fields in Minnesota, USA. A linear response of N2O production rate () to NO2− was observed at concentrations below 60 μg N g−1 soil in both nonsterile and sterilized soils. Rate coefficients (Kp) relating to NO2− varied over two orders of magnitude and were correlated with pH, total nitrogen, and soluble and total carbon (C). Total C explained 84% of the variance in Kp across all samples. Abiotic processes accounted for 31–75% of total N2O production. Biological reduction of NO2− was enhanced as oxygen (O2) levels were decreased from above ambient to 5%, consistent with nitrifier denitrification. In contrast, nitrate (NO3−)‐reduction, and the reduction of N2O itself, were only stimulated at O2 levels below 5%. Greater temperature sensitivity was observed for biological compared with chemical N2O production. Steady‐state model simulations predict that NO2− levels often found after fertilizer applications have the potential to generate substantial N2O fluxes even at ambient O2. This potential derives in part from the production of N2O under conditions not favorable for N2O reduction, in contrast to N2O generated from NO3− reduction. These results have implications with regard to improved management to minimize agricultural N2O emissions and improved emissions assessments.
Primary and recurrent embryonal sarcoma of the liver: clinicopathological and immunohistochemical analysis
Authors: Zheng J‐M , Tao X , Xu A‐M , Chen X‐F , Wu M‐C , Zhang S‐H 
Published: June 2007

Aims:  To evaluate primary and recurrent embryonal sarcoma of the liver and to improve recognition of its morphological variants and immunohistochemical features.Methods and results:  Fourteen primary and two recurrent cases of hepatic embryonal sarcoma were evaluated histologically and investigated immunohistochemically with a panel of antibodies using the EnVision+ system. They were usually single, large, globular masses with solid and cystic gelatinous areas. Microscopic features included spindle, oval, stellate, epithelioid or multinucleated cells loosely or densely arranged in a myxomatous matrix. Entrapped bile ducts and hepatic cords were often present at the periphery of the tumours. Intracellular and extracellular periodic acid–Schiff‐positive, diastase‐resistant hyaline globules were commonly present. Recurrent tumours showed greater cellularity, anaplasia and pluripotential differentiation compared with the primary tumour. Immunohistochemistry showed evidence of widely divergent differentiation into mesenchymal and epithelial phenotypes.Conclusions:  Embryonal sarcoma of the liver may undergo pluripotential differentiation and diagnosis should be based mainly on morphological features. Immunohistochemistry has no specific or diagnostic relevance, but, by using a panel of antibodies, may help to exclude other tumours.
Occurrence of oxidative impairments, response of antioxidant defences and associated biochemical perturbations in male reproductive milieu in the Streptozotocin‐diabetic rat
Authors: Shrilatha B. , Muralidhara  
Published: June 2007

SummaryOxidative stress is implicated to play a vital role in the pathogenesis of various diabetic complications. While reproductive dysfunction is a well recognized consequence of diabetes mellitus, the underlying mechanisms are poorly understood. The present study aims to obtain insights into the incidence, extent and progression of oxidative impairments in testis and epididymal sperm (ES) in streptozotocin (STZ)‐induced diabetic rat during early and progressive phase. Adult rats (CFT‐Wistar strain) rendered diabetic by an acute dose of STZ (60 mg/kg bw, i.p.) were examined for induction of hyperglycaemia at 72 h, followed by the assessment of oxidative impairments in testis and ES over a 6‐week period. Oxidative damage was ascertained by measuring the malondialdehyde levels, reactive oxygen species (ROS) generation, alterations in antioxidant defences and extent of protein oxidation. STZ induced a significant (2.5‐fold) increase in blood glucose levels. In diabetic rats, both testis and ES showed enhanced status of lipid peroxidation measured as increased TBARS and ROS from week 2 onwards. These impairments in testis were consistent, progressive and accompanied by marked alterations in antioxidant defences and elevated protein carbonyls. Varying degree of reduction in the specific activities of antioxidant enzymes was evident in testis and ES, while the activity of glutathione‐S‐transferase (GST) was significantly elevated. Reduced glutathione (GSH) and vitamin E levels were consistently reduced in testis. Lipid dysmetabolism measured in terms of increased cholesterol, triglycerides and phospholipids was evident only beyond week 2 in diabetic testis. Taken together, these results indicate that the testis and ES are indeed subjected to significant oxidative stress in the STZ‐diabetic rat both during early as well as progressive phase. It is hypothesized that oxidative impairments in testis which develop over time may at least in part contribute towards the development of testicular dysfunction eventually leading to testicular degeneration which culminates in reduced fertility during the progressive phase of STZ‐induced diabetes in adult rats.
Relevance of microRNAs in normal and malignant development, including human testicular germ cell tumours
Authors: Looijenga L. H. J. , Gillis A. J. M. , Stoop H. , Hersmus R. , Oosterhuis J. W. 
Published: June 2007

SummaryThe dogma of genome functionality has recently been challenged by identification of non‐protein‐encoding RNAs, including mi(cro)RNAs. These relatively small sequences interact with mRNA and in the mammalian system, are involved in fine‐tuning the process of translation. miRNAs have been found to be of crucial importance for normal development, including stem cell formation. Recent interesting fundamental observations will be discussed in this paper, as well as their impact on the genesis of human germ cell tumours (GCTs), in particular those of the adult testis, seminomas and non‐seminomas (type II), and spermatocytic seminomas (type III). miRNA cluster 371–373 is specifically involved in inhibition of cellular senescence induced by oncogenic stress in the type II GCTs. This explains the unusual presence of wild type P53, characteristic of this type of solid cancer. Specific sets of differentiating miRNA were found to characterize the various differentiation lineages within the GCTs, which simulate normal embryonic development.
Analysis of gene expression in normal and neoplastic human testis: new roles of RNA
Authors: Novotny G. W. , Nielsen J. E. , Sonne S. B. , Skakkebaek N. E. , Rajpert‐De Meyts E. , Leffers H. 
Published: June 2007

SummaryLarge‐scale methods for analysing gene expression, such as microarrays, have yielded a wealth of information about gene expression at the mRNA level. However, expression of alternative transcripts, together with the presence of a wide range of largely undescribed RNA transcripts combined with regulation from the RNA interference pathway, may cause misinterpretations when trying to base conclusions from expression data derived from studies at the mRNA level. With HLXB9, PRM1, DICER and E2F1 as examples, we here show a range of situations that can occur when investigating gene expression, and give recommendations for the complementary methods that can verify gene expression data from large‐scale studies, as well as give new information regarding the regulation of specific genes. Especially, we show that the absence of a protein despite high expression of the corresponding mRNA can be caused by expression of miRNAs targeting the mRNA. Additionally, we show through cloning the presence of both known and new miRNAs in the testis emphasizing the necessity for following up mRNA expression data by investigating expression at the protein level.
Oxygen uptake by mitochondria in demembranated human spermatozoa: a reliable tool for the evaluation of sperm respiratory efficiency
Authors: Ferramosca A. , Focarelli R. , Piomboni P. , Coppola L. , Zara V. 
Published: June 2007

SummaryIn this work we report a relatively simple and fast method for analysing oxygen consumption and therefore mitochondrial functionality, in individual human ejaculates. This oxygraphic method requires a low number of cells, is highly reproducible and linearly correlates with sperm concentration. Our results have shown that oxygen uptake by mitochondria of demembranated sperm cells from normozoospermic subjects is significantly stimulated by a large set of respiratory substrates and ADP. The respiratory control ratio (RCR) values indicate a good coupling between respiration and phosphorylation by sperm mitochondria and thus a well preserved integrity of the mitochondria themselves. Interestingly, whereas the rates of oxygen uptake, as expected, changed with different sperm concentrations, the RCR values remained constant, thus demonstrating a linear response of the assay. In asthenozoospermic subjects, however, a significant decrease in the sperm respiratory efficiency was found. The results obtained suggest that this method, besides its potential clinical application, could be useful for a deeper understanding of the biochemical properties of sperm mitochondria and their role in ATP production in human spermatozoa.
Testis and prostate cancer incidence in ethnic groups in South East England
Authors: Jack R. H. , Davies E. A. , Møller H. 
Published: June 2007

SummaryInternational variations in the incidence of testis and prostate cancer are well established. Data from the USA have also shown differences between White and Black men; however, there has been little work on ethnicity and cancer incidence in the UK, due to incomplete ethnicity information in cancer registries. The Hospital Episode Statistics (HES) dataset has more complete information on self‐assigned ethnicity for inpatients of English NHS hospitals. Data on 194 590 male patients resident in South East England diagnosed with cancer between 1998 and 2003 were extracted from the Thames Cancer Registry (TCR). Of these, ethnicity information from HES was obtained for 123 507 (63%), ethnicity information from TCR was available for a further 5909 (3%), and no ethnicity was available for 65 174 (33%). Compared with ‘All White’ men, testis cancer incidence was significantly lower in Indian, Pakistani, Bangladeshi, Other Asian, Black Caribbean, Black African, Other Black and Chinese men. Prostate cancer incidence was significantly increased in Black Caribbean, Black African, Other Black, Indian, Pakistani, Mixed White and Black Caribbean and Mixed White and Black African groups compared with ‘All White’ men. Bangladeshi and Chinese men had a significantly decreased incidence of prostate cancer. The incidence of prostate cancer in Indian and Pakistani men showed convergence towards the rates in the white population, suggesting the existence of modifiable risk factors in these men. Most other variations in these data are consistent with international comparisons, and indicate that genetic variations in susceptibility are very influential.
Infiltration of polymorphonuclear cells into the post‐ischaemic myocardium is dependent on β2 and α4 integrins
Authors: Légaré Jean‐Francois , Oxner Adam , Heimrath Olivier , Issekutz Thomas 
Published: June 2007

SummaryPolymorphonuclear cells (PMN) are believed to be important effector cells responsible the myocardial damage seen following ischaemia. However, the exact kinetics of their migration remains controversial. Isolated PMN (10 × 106 cells) labelled with 51Cr were injected into four groups of Lewis rats: 0 h (T0h; n = 13), 2 h (T2h; n = 7), 4 h (T4h; n = 7) or 6 h following ischaemia (T6h; n = 4). In all recipients, a left thoracotomy and ligation of the left anterior descending coronary was performed. Control animals underwent sham thoracotomy (n = 10). All animals were killed at 24 h and the radioactivity in the tissue measured to estimate labelled PMN migration. Monoclonal antibody blockade was also performed in experimental animals to assess the contribution of β2 and α4 integrins to the PMN migration (n = 32). Labelled PMN migration to the myocardium was similar in all experimental groups, T0–T6h (7.2–11 × 105 labelled PMN) and significantly higher than sham controls (2.2 × 105 labelled PMN; P = 0.03). In contrast PMN migration to dermal inflammatory sites was highest in T0h group, and reached background level in the T4h and T6h groups. β2 integrin blockade inhibited labelled PMN migration by 32%. Blockade of α4 integrin inhibited PMN migration by 30% while the combined β2 + α4 blockade resulted in 63% inhibition of labelled PMN migration compared to treatment with isotype control antibody (P = 0.035). PMN migration following myocardial ischaemia persists over several hours after myocardial infarction and does not follow similar migration kinetics to dermal inflammation. Our findings also suggest that PMN migration is dependent equally on β2 and α4 integrins.