bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of abrupt climate change on the ice‐age vegetation of the Central American lowlands
Authors: Correa‐Metrio Alexander , Bush Mark B. , Hodell David A. , Brenner Mark , Escobar Jaime , Guilderson Tom 
Published: November 2011

AbstractAim  To investigate the effects of abrupt climate change in the North Atlantic on the vegetation history of lowland Central America. We use palynological evidence from a Central American lake on the Yucatan Peninsula to evaluate the effects of rapid climate changes during the last ice age, between 65 and 8 ka.Location  Lake Petén‐Itzá, lowlands of northern Guatemala.Methods  Sediment core PI‐6 was sampled at c. 170‐year resolution for pollen and charcoal analysis in order to construct a temporal sequence of environmental change. Uni‐ and multivariate statistical analyses were performed on the pollen dataset to test whether there was an association between Heinrich events in the North Atlantic and vegetation changes in the Central American lowlands.Results  Pollen analysis revealed that the composition of plant assemblages on the Yucatan Peninsula varied in phase with rapid changes in North Atlantic climate. Pine savannas were the main vegetation type between c. 60 and 47 ka. These savannas gave way to pine–oak (Pinus–Quercus) forests in the latter half of the last ice age. Marked episodes of replacement of the pine–oak assemblage by xeric‐tolerant taxa occurred during Heinrich events. The Last Glacial Maximum (LGM) was characterized by mesic conditions.Main conclusions  The pollen record from Lake Petén‐Itzá showed that vegetation changes associated with Heinrich events were more significant than those associated with the LGM. Each Heinrich event produced a characteristic shift towards xeric taxa. Although colder than Heinrich events, the LGM on the Yucatan Peninsula was relatively moist, and the presumed savannization of the landscape during the maximum cooling of the last glacial was not supported by our data. Our findings suggest alternative scenarios for plant diversification and genetic interchange during glacial times, and also indicate that vegetation in tropical continental settings was not as stable as previously thought.
The virtue of temperance: built‐in negative regulators of quorum sensing in Pseudomonas
Authors: Venturi Vittorio , Rampioni Giordano , Pongor Sándor , Leoni Livia 
Published: November 2011

SummaryMany bacteria are now believed to produce small signal molecules in order to communicate in a process called quorum sensing (QS), which mediates cooperative traits and a co‐ordinated behaviour. Pseudomonads have been extensively studied for their QS response highlighting that it plays a major role in determining their lifestyle. The main QS signal molecules produced by Pseudomonas belong to the family of N‐acyl‐homoserine lactones (AHLs); these are synthesized by a LuxI‐family synthase and sensed by a LuxR‐family regulator. Most often in Pseudomonas, repressor genes intergenically located between luxI and luxR form an integral part of QS system. Recent studies have highlighted an important role of these repressors (called RsaL and RsaM) in containing the QS response within cost‐effective levels; this is central for pseudomonads as they have very versatile genomes allowing them to live in constantly changing and highly dynamic environments. This review focuses on the role played by RsaL and RsaM repressors and discusses the important implications of this control of the QS response.
Together yes, but not coupled: new insights into the roles of RAD51 and DMC1 in plant meiotic recombination
Authors: Pradillo Mónica , López Eva , Linacero Rosario , Romero Concepción , Cuñado Nieves , Sánchez‐Morán Eugenio , Santos Juan L. 
Published: November 2011

SummaryThe eukaryotic recombinases RAD51 and DMC1 are essential for DNA strand‐exchange between homologous chromosomes during meiosis. RAD51 is also expressed during mitosis, and mediates homologous recombination (HR) between sister chromatids. It has been suggested that DMC1 might be involved in the switch from intersister chromatid recombination in somatic cells to interhomolog meiotic recombination. At meiosis, the Arabidopsis Atrad51 null mutant fails to synapse and has extensive chromosome fragmentation. The Atdmc1 null mutant is also asynaptic, but in this case chromosome fragmentation is absent. Thus in plants, AtDMC1 appears to be indispensable for interhomolog homologous recombination, whereas AtRAD51 seems to be more involved in intersister recombination. In this work, we have studied a new AtRAD51 knock‐down mutant, Atrad51‐2, which expresses only a small quantity of RAD51 protein. Atrad51‐2 mutant plants are sterile and hypersensitive to DNA double‐strand break induction, but their vegetative development is apparently normal. The meiotic phenotype of the mutant consists of partial synapsis, an elevated frequency of univalents, a low incidence of chromosome fragmentation and multivalent chromosome associations. Surprisingly, non‐homologous chromosomes are involved in 51% of bivalents. The depletion of AtDMC1 in the Atrad51‐2 background results in the loss of bivalents and in an increase of chromosome fragmentation. Our results suggest that a critical level of AtRAD51 is required to ensure the fidelity of HR during interchromosomal exchanges. Assuming the existence of asymmetrical DNA strand invasion during the initial steps of recombination, we have developed a working model in which the initial step of strand invasion is mediated by AtDMC1, with AtRAD51 required to check the fidelity of this process.
ZINC TOLERANCE INDUCED BY IRON 1 reveals the importance of glutathione in the cross‐homeostasis between zinc and iron in Arabidopsis thaliana
Authors: Shanmugam Varanavasiappan , Tsednee Munkhtsetseg , Yeh Kuo‐Chen 
Published: November 2011

SummaryZinc is an essential micronutrient for plants, but it is toxic in excess concentrations. In Arabidopsis, additional iron (Fe) can increase Zn tolerance. We isolated a mutant, zinc tolerance induced by iron 1, designated zir1, with a defect in Fe‐mediated Zn tolerance. Using map‐based cloning and genetic complementation, we identified that zir1 has a mutation of glutamate to lysine at position 385 on γ‐glutamylcysteine synthetase (GSH1), the enzyme involved in glutathione biosynthesis. The zir1 mutant contains only 15% of the wild‐type glutathione level. Blocking glutathione biosynthesis in wild‐type plants by a specific inhibitor of GSH1, buthionine sulfoximine, resulted in loss of Fe‐mediated Zn tolerance, which provides further evidence that glutathione plays an essential role in Fe‐mediated Zn tolerance. Two glutathione‐deficient mutant alleles of GSH1, pad2‐1 and cad2‐1, which contain 22% and 39%, respectively, of the wild‐type glutathione level, revealed that a minimal glutathione level between 22 and 39% of the wild‐type level is required for Fe‐mediated Zn tolerance. Under excess Zn and Fe, the recovery of shoot Fe contents in pad2‐1 and cad2‐1 was lower than that of the wild type. However, the phytochelatin‐deficient mutant cad1‐3 showed normal Fe‐mediated Zn tolerance. These results indicate a specific role of glutathione in Fe‐mediated Zn tolerance. The induced accumulation of glutathione in response to excess Zn and Fe suggests that glutathione plays a specific role in Fe‐mediated Zn tolerance in Arabidopsis. We conclude that glutathione is required for the cross‐homeostasis between Zn and Fe in Arabidopsis.
Distribution Patterns of Mast Cells in the Uterus of Pregnant Meishan Pigs
Authors: Liu YX , Yu M , Wang C , Peng KM , Liu HZ 
Published: November 2011

ContentsThe present study was performed to investigate the numerical distribution of mast cells (MCs) in the uteri of pregnant Meishan pigs to explore the functions of MCs in pig pregnancy. The uterine samples from pregnant (on days 15, 26 and 50 of gestation) pigs were obtained respectively and stained with toluidine blue. The results were as follows: MCs were constitutively located in the uterus of the Meishan pig, with the distribution varying with gestational stages. On days 15 and 26 of gestation, MCs were mainly distributed around the blood vessels and uterine glands within the endometrium. On day 50 of gestation, MCs were mostly distributed in the myometrium. These results indicated that uterine MCs possibly have versatile functions in pig pregnancy.
Mitochondria as a source and target of lipid peroxidation products in healthy and diseased heart
Authors: Anderson Ethan J , Katunga Lalage A , Willis Monte S 
Published: November 2011

Summary1. The heart is a highly oxidative organ in which cardiomyocyte turnover is virtually absent, making it particularly vulnerable to accumulation of lipid peroxidation products (LPP) formed as a result of oxidative damage.2. Reactive oxygen and nitrogen species are the most common electrophiles formed during lipid peroxidation and lead to the formation of both stable and unstable LPP. Of the LPP formed, highly reactive aldehydes are a well‐recognized causative factor in ageing and age‐associated diseases, including cardiovascular disease and diabetes.3. Recent studies have identified that the mitochondria are both a primary source and target of LPP, with specific emphasis on aldehydes in cardiomyocytes and how these affect the electron transport system and Ca2+ balance.4. Numerous studies have found that there are functional consequences in the heart following exposure to specific aldehydes (acrolein, trans‐2‐hexanal, 4‐hydroxynonenal and acetaldehyde). Because these LPP are known to form in heart failure, cardiac ischaemia–reperfusion injury and diabetes, they may have an underappreciated role in the pathophysiology of these disease processes.5. Lipid peroxidation products are involved in the transcriptional regulation of endogenous anti‐oxidant systems. Recent evidence demonstrates that transient increases in LPP may be beneficial in cardioprotection by contributing to mitohormesis (i.e. induction of anti‐oxidant systems) in cardiomyocytes. Thus, exploitation of the cardioprotective actions of the LPP may represent a novel therapeutic strategy for future treatment of heart disease.
Effect of surgical repair on testosterone production in infertile men with varicocele: A meta‐analysis
Authors: Li Fuping , Yue Huanxun , Yamaguchi Kohei , Okada Keisuke , Matsushita Kei , Ando Makoto , Chiba Koji , Fujisawa Masato 
Published: November 2011

Objectives:  To determine the effect of surgical varicocele repair in improving testicular Leydig cell function as shown by increased testosterone production.Methods:  Eligible studies were searched in Medline and the Pubmed database, and cross‐referenced as of 31 May 2011 using the terms “varicocele,”“testosterone” and “surgery.” The database search, quality assessment and data extraction were independently carried out by two reviewers. Only studies including patients with testosterone evaluation before and after surgery were considered for the analysis. A systematic review and meta‐analysis was carried out for continues variables using random effect models.Results:  Out of 125 studies, a total of nine were selected, including 814 patients. The combined analysis showed that mean serum testosterone levels after surgical treatment increased by 97.48 ng/dL (95% confidence interval 43.73–151.22, P = 0.0004) compared with preoperative levels.Conclusions:  Surgical treatment of varicocele significantly increases testosterone production and improves testicular Leydig cell function.
Bird diversity patterns in Neotropical temperate farmlands: The role of environmental factors and trophic groups in the spring and autumn
Authors: APELLANIZ MELISA , BELLOCQ M. ISABEL , FILLOY JULIETA 
Published: November 2011

AbstractProductivity, habitat heterogeneity and environmental similarity are of the most widely accepted hypotheses to explain spatial patterns of species richness and species composition similarity. Environmental factors may exhibit seasonal changes affecting species distributions. We explored possible changes in spatial patterns of bird species richness and species composition similarity. Feeding habits are likely to have a major influence in bird–environment associations and, given that food availability shows seasonal changes in temperate climates, we expect those associations to differ by trophic group (insectivores or granivores). We surveyed birds and estimated environmental variables along line‐transects covering an E‐W gradient of annual precipitation in the Pampas of Argentina during the autumn and the spring. We examined responses of bird species richness to spatial changes in habitat productivity and heterogeneity using regression analyses, and explored potential differences between seasons of those responses. Furthermore, we used Mantel tests to examine the relationship between species composition similarity and both the environmental similarity between sites and the geographic distance between sites, also assessing differences between seasons in those relationships. Richness of insectivorous birds was directly related to primary productivity in both seasons, whereas richness of seed‐eaters showed a positive association with habitat heterogeneity during the spring. Species composition similarity between assemblages was correlated with both productivity similarity and geographic proximity during the autumn and the spring, except for insectivore assemblages. Diversity within main trophic groups seemed to reflect differences in their spatial patterns as a response to changes between seasons in the spatial patterns of food resources. Our findings suggest that considering different seasons and functional groups in the analyses of diversity spatial pattern could contribute to better understand the determinants of biological diversity in temperate climates.
The components of the putative iron transport system in the cyanobacterium Anabaena sp. PCC 7120
Authors: Stevanovic Mara , Hahn Alexander , Nicolaisen Kerstin , Mirus Oliver , Schleiff Enrico 
Published: November 2011

SummaryIron uptake in Gram‐negative bacteria involves four distinct steps: (i) siderophore synthesis, (ii) siderophore secretion into the extracellular space, (iii) iron chelation by the siderophores, and (iv) siderophore/iron uptake via complexes in the outer membrane and the intermembrane space as well as in the plasma membrane. This process is well characterized for some proteobacterial systems, but largely unexplored and scarcely investigated in cyanobacteria such as the heterocyst‐forming cyanobacterium Anabaena sp. PCC 7120. Two putative siderophore synthesis clusters have been recently identified in this cyanobacterium. In addition, the export system for the main siderophore, schizokinen, secreted by Anabaena sp. PCC 7120 was described as well as the outer membrane transporter for its import from the extracellular space. We present the identification of components of three additional systems involved in siderophore‐mediated iron uptake under iron‐limiting conditions, namely TonB3, the ExbB3/ExbD3 and the Fhu systems. The transcription level of these genes is elevated under iron limitations and decreased under excess iron, while the expression levels of other members of these gene families and systems are impacted in distinct ways by other environmental conditions. Mutants of the tonB3, exbB3/exbD3 and fhu genes show an iron starvation phenotype. Thus, Anabaena sp. has a similar, yet distinct system for siderophore‐dependent iron uptake compared with other proteobacteria.
External eggshell morphology of Anastrepha fruit flies (Diptera: Tephritidae)
Authors: Figueiredo Julia V. A. , Perondini André L. P. , Ruggiro Eliana M. , Prezotto Leandro F. , Selivon Denise 
Published: November 2011

AbstractFigueiredo J.V.A., Perondini A.L.P., Ruggiro EM., Prezotto LF. and Selivon D. (2011). External eggshell morphology of Anastrepha fruit flies (Diptera: Tephritidae). —Acta Zoologica (Stockholm) 00:1–9.The eggshell external morphology of Anastrepha species of different taxonomic intrageneric groups was determined by light and scanning electron microscopy. The eggs of Anastrepha alveata Stone and A. consobrina (Loew) are described for the first time, and a more detailed description of previously studied eggs from A. amita Zucchi, A. pickeli Lima, A. bistrigata Bezzi, A. grandis (Macquart), A. obliqua (Macquart), A. pseudoparallela (Loew), A. striata Schiner, A. suspensa (Loew), and A. zenildae Zucchi is presented. Several relatively plastic morphological characters of the eggs were discerned, such as length, width, tapering, curvature, chorion ornamentation, respiratory lobes, and position of the micropyle. Scores were attributed to these characters, allowing a comparison of egg morphology among 17 species of Anastrepha. A cluster analysis based on these scores did not group the eggs according to the taxonomic intrageneric groups of the species. Nonetheless, this analysis indicated that the egg of each species can be described by a set of morphological scores. The possibility of species identificaton using immature stages will be of great help for the taxonomy of Anastrepha fruit flies.
BMEY as a fisheries management target
Authors: Grafton Quentin R , Kompas Tom , Che Tuong N , Chu Long , Hilborn Ray 
Published: November 2011

AbstractThis paper evaluates the implications of managing fisheries to achieve a BMEY target, or a biomass level that maximizes net economic returns in the fishery, and discusses the role of private ownership and the trade‐offs between economic and conservation benefits in this setting. The paper shows how a BMEY target can be used to: (i) determine relative employment and profitability measures; (ii) account for both the harvesting and processing sectors; and (iii) incorporate the interests of consumers and producers of fish. The profits–employment trade‐off of adopting a BMEY target vs. a traditional BMSY target is calculated using a model and data from the Western and Central Pacific tuna fisheries (WCPTF), while a generic bioeconomic model is constructed to show numerical values of BMEY from including processing and/or retail sectors and the consumer benefits of harvesting fish. For the WCPTF, results show that the long‐term gains per job lost from pursuing a BMEY target are worth several times the value of the average GDP per capita of Pacific Island Countries. The generic bioeconomic model shows that including a processing and/or retail sector, as well as measures of consumer benefit, lowers the BMEY target. However, there remains a broad range of parameter values for which BMEY is still greater than biomass at maximum sustainable yield, or BMSY. The paper also illustrates cases where BMEY > BMSY at different values of the price elasticity of demand, margins for processing and/or retail sectors and values of the discount rate.
Increasing fish consumption for better health – are we being advised to eat more of an inherently unsustainable protein?
Authors: Mitchell M. 
Published: November 2011

SummaryThe health benefits of fish consumption are manifold and well understood from scientific and nutritional perspectives. Yet, seafood is the last great hunted human food resource, and a number of the world's fisheries are currently depleted through overfishing. There is a dilemma for consumers who, in line with UK Government advice, wish to eat seafood as a healthy, nutritious (and tasty) lifestyle choice and their concerns over the sustainability of the fish that they enjoy. This paper explores this dilemma by examining the status of world seafood stocks and discussing some of the strategies used by seafood retailers and brands to ensure that responsible and sustainable choices are available for the UK consumer.
Does consuming seasonal foods benefit the environment? Insights from recent research
Authors: Brooks M. , Foster C. , Holmes M. , Wiltshire J. 
Published: November 2011

SummaryThe profile of seasonal foods has been raised in recent years, with information about ‘in‐season’ produce being made available to consumers through a variety of channels, including television programmes, magazine articles and websites. ‘Eating seasonally’ has also increasingly been encouraged by government initiatives and supported by other agencies and organisations. This article draws on findings of recent research by ADAS, EuGeos and SERIO to explore the notion of ‘seasonal food’ and probe the link between ‘eating seasonally’ and a reduction of environmental impacts in the food chain.
Age standardization in mapping adult overweight and obesity trends in the WHO European Region
Authors: Doak C. M. , Wijnhoven T. M. A. , Schokker D. F. , Visscher T. L. S. , Seidell J. C. 
Published: November 2011

SummaryThis study aims to improve comparability of available data within the World Health Organization (WHO) European Region taking into account differences related to the aging of the population. Surveys were included if they were conducted on adults aged 25–64 years between 1985 and 2010 in the WHO European Region. Overweight/obesity prevalences were adjusted to the European standard population aged 25–64. Data were entered for each of the 5‐year categories between 1981 and 2010. Measured height and weight data were available for males in 16 and females in 24 of the 53 countries. The 50–64‐year‐olds had higher prevalence of overweight and obesity as compared to the 25–49‐year‐olds. This pattern occurs in every country, by male and female, in almost all surveys. Age‐standardized overweight prevalence was higher among males than females in all countries. Trend data showed increases in most countries. Age‐standardized maps were based on self‐reported data because of insufficient availability of measured data. Results showed more countries with available data as well as the higher category of obesity in the later surveys. Measured values are needed and age adjustment is important in documenting emerging overweight and obesity trends, independent of demographic changes, in the WHO European Region.