bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA Double Strand Break Repair inE. coliPerturbs Cell Division and Chromosome Dynamics
Authors: White M.A. , Darmon E. , Lopez-Vernaza M.A. , Leach D.R.F. 
Published: October 2019

AbstractTo prevent the transmission of damaged genomic material between generations, cells require a system for accommodating DNA repair within their cell cycles. We have previously shown thatEscherichia colicells subject to a single, repairable site-specific DNA double-strand break (DSB) per DNA replication cycle reach a new average cell length, with a negligible effect on population growth rate. We show here that this new cell size distribution is caused by a DSB repair-dependent delay in completion of cell division. This delay occurs despite unperturbed cell size regulated initiation of both chromosomal DNA replication and cell division. Furthermore, despite DSB repair altering the profile of DNA replication across the genome, the time required to complete chromosomal duplication is invariant. The delay in completion of cell division is accompanied by a DSB repair-dependent delay in individualization of sister nucleoids. We suggest that DSB repair events create inter-sister connections that persist until those chromosomes are separated by a closing septum.Author SummaryThe bacteriumEscherichia colihas a remarkable cell cycle where overlapping rounds of DNA replication can occur in a single generation between cell birth and division. This implies a complex coordination network between growth, genome duplication and cell division to ensure that the right number of genomes are created and distributed to daughter cells at all growth rates. This network must be robust to a number of unpredictable challenges. One such challenge is broken DNA, something that inE. coliis estimated to occur in ~20% of cell division cycles. In this work we perturb theE. colicell cycle by elevating the frequency of repairable DNA double-strand breaks to determine which parameters of the cell cycle are conserved and which are changed. Our results demonstrate that this perturbation does not alter the average cell size at initiation of DNA replication or initiation of cell division. Furthermore, it does not alter the time taken to replicate the genome or the generation time. However, it does delay the segregation of the DNA to daughter cells and the completion of cell division explaining the increase in average cell size observed previously.
Larviposition site selection mediated by volatile semiochemicals of larval origin in Glossina palpalis gambiensis
Authors: Geoffrey Gimonneau , Ouedraogo Romaric , Ernest Salou , Jean-Baptiste Rayaisse , Buatois Bruno , Solano Philippe , Dormont Laurent , Roux Olivier , Bouyer Jérémy 
Published: October 2019

AbstractTsetse flies (Diptera: Glossinidae) are the cyclical vectors of trypanosomes, the causative agents of African animal trypanosomosis or nagana in animals and human African trypanosomosis or sleeping sickness in humans. Tsetse flies are K-strategist species with the deposition of a single larva at 10 days intervals in specific sites. As larviposition site selection will strongly impact reproductive success, it is obvious that the selection of larviposition sites is not random and is under strong selective processes, probably mediated by specific cues as suggested by the existence of an aggregation factor in the Morsitans and Fusca groups. This study aimed to highlight the existence of an aggregation effect in the Palpalis group and to test for its chemical nature. We studied the larviposition site selection of Glossina palpalis gambiensis according to the presence of conspecific and heterospecific larvae buried in substrates in different settings. Three sets of experiments were performed with either individual or grouped (n = 50) gravid females, and with physical access to substrate or not. In both individual and grouped larviposition experiments, females selected significantly more often trays conditioned by larvae (P<0.005), either conspecific or heterospecific even in the absence of physical contact with the substrate. These results highlight the first evidence for larviposition site selection mediated by volatile semiochemicals of larval origin in Glossina palpalis gambiensis. However, these compounds seem not to be species-specific and therefore offer new avenues for the behavioural manipulation of these vectors and for the development of new vector control tools targeting gravid females.Author summaryLarviposition site selection in tsetse flies is govern by several biotic and abiotic factors that lead to an aggregation effect of larvae. Among those, larvae are suspected to produce chemicals that drive females to breeding site but little information is available. This study aimed to highlight the existence of an aggregation effect of larval origin in the Palpalis group and to test for its chemical nature. Through behavioural larviposition choice experiments, we showed that females of Glossina palpalis gambiensis deposit their larvae significantly more often in trays conditioned either by conspecific or heterospecific larvae, even in the absence of physical contact with the substrate. These results highlight the first evidence for aggregation effect in Glossina palpalis gambiensis mediated by volatile semiochemicals of larval origin. Isolation and identification of these chemicals should offer new avenues for the behavioural manipulation of these vectors and for the development of new vector control tools targeting gravid females.
Optogenetic mapping of feeding and self-stimulation within the lateral hypothalamus of the rat
Authors: Urstadt Kevin R. , Berridge Kent C. 
Published: October 2019

AbstractThe lateral hypothalamus (LH) regulates eating and motivation, and includes several anatomical subregions. This study explored localization of function across different LH subregions in controlling food intake stimulated by optogenetic channelrhodopsin excitation, and in supporting laser self-stimulation. We particularly compared the tuberal LH, the posterior LH, and the lateral preoptic area. Local diameters of tissue optogenetically stimulated within LH were assessed by measuring laser-induced Fos plumes and Jun plumes via immunofluorescence surrounding optic fiber tips, and were used to map localization of function for effects elicited by LH optogenetic stimulation. Optogenetic stimulation of the tuberal subsection of the LH behaviorally produced the most robust food intake initially, but produced only mild laser self-stimulation in the same rats. However, after repeated exposures to optogenetic stimulation, tuberal LH behavioral profiles shifted toward more self-stimulation and less food intake. By contrast, stimulation of the lateral preoptic area produced relatively little food intake or self-stimulation, either initially or after extended stimulation experience. Stimulation in the posterior LH subregion supported moderate self-stimulation, but not food intake here, and at higher laser intensity shifted valence to evoke escape behaviors. We conclude that the tuberal LH subregion may best mediate increases in food intake stimulated by optogenetic excitation. However, incentive motivational effects of tuberal LH stimulation may shift toward self-stimulation behavior after repeated stimulation. By contrast, the lateral preoptic area and posterior LH do not as readily elicit either eating behavior or laser self-stimulation, and may be more prone to higher-intensity aversive effects.
Truncated WT1 protein isoform expression is increased in MCF-7 cells in a long-term estrogen depletion
Authors: Santiago Saavedra-Alonso , Pablo Zapata-Benavides , Edgar Mendoza-Gamboa , Ana Karina Chavez-Escamilla , Mariela Arellano-Rodríguez , Cristina Rodriguez-Padilla 
Published: October 2019

AbstractBackgroundThe WT1 gene codes for a transcription factor that presents several protein isoforms with diverse biological properties, capable of positively and negatively regulating genes involved in proliferation, differentiation, and apoptosis. WT1 protein is overexpressed in more than 90% of breast cancer, however, its role during tumor progression is still unknown.MethodologyIn this work were analyzed the expression of WT1 isoforms (36-38 kDa and 52-54 kDa, and 17 AA (+/−) and KTS (+/−)) in breast cancer cells. On the other hand, with the purpose of mimicking the process of switch from a hormone-dependent to a hormone-independent neoplasm, an assay was performed using the MCF-7 cells cultured in long-term estrogen depletion (MCF-7 LTED cells) to determine the WT1 protein isoforms expression by western blot and RT-PCR, and Her2/neu and Estrogen receptor (ER) expression by quantitative RT-PCR assay. Growth kinetics and sensitivity to tamoxifen were performed in the MCF-7 LTED cells by trypan blue exclusion.ResultsThe western blot shows the presence of the 52-54 kDa WT1 isoform in the ER (+) breast cancer cells, but not in the ER (−) cells. The 36-38 kDa WT1 isoform was detected in all the breast cancer cell lines analyzed. Using specific primers was found that 17 AA (+) / KTS (−) WT1 isoform was the most frequent in four breast cancer cell lines. During the sampling of the MCF-7 cells in estrogen depletion, an increase in the short-term of 52-54 kDa WT1 isoform was observed and this was kept until week 13, thereafter, its expression was absent; alternately, the 36-38 kDa WT1 isoform was observed from week 1 and it remained constant until week 27. MCF-7 LTED cells growth kinetic decreased 1.4 folds and were not sensitive to tamoxifen antiproliferative effect (p ≤ 0.05). Finally, were observed an increase of expression of ER and Her2/neu in the MCF-7 LTED cells.ConclusionsThe 36-38 kDa WT1 isoform expression occurs during the modifications of the hormonal environment, suggesting that it may be playing an important role in its adaptation and tumor progression.
Mechanochemical Model of Transcriptional Bursting
Authors: Klindziuk A. , Meadowcroft B. , Kolomeisky A. B. 
Published: October 2019

ABSTRACTPopulations of genetically identical cells generally show a large variability in cell phenotypes, which is typically associated with the stochastic nature of gene expression processes. It is widely believed that a significant source of such randomness is the transcriptional bursting, which is when periods of active production of RNA molecules alternate with periods of RNA degradation. However, the molecular mechanisms of such strong fluctuations remain unclear. Recent studies suggest that DNA supercoiling, which happens during transcription, might be directly related to the bursting behavior. Stimulated by these observations, we developed a stochastic mechano-chemical model of supercoiling-induced transcriptional bursting where the RNA synthesis leads to the buildup of torsion in DNA. This slows down the RNA production until binding of an enzyme gyrase to DNA, which releases the stress and allows for the RNA synthesis to restart with the original rate. Using a thermodynamically consistent coupling between mechanical and chemical processes, dynamic properties of transcription are explicitly evaluated. In addition, a first-passage method to evaluate the dynamics of transcription is developed. Theoretical analysis shows that the transcriptional bursting is observed when both the supercoiling and the mechanical stress-release due to gyrase are present in the system. It is also found that the overall RNA production rate is not constant and depends on the number of previously synthesized RNA molecules. A comparison with experimental data on bacteria allows us to evaluate the energetic cost of supercoiling during transcription. It is argued that the relatively weak mechanochemical coupling allows transcription to be regulated most effectively.SIGNIFICANCETranscriptional bursting has been cited as one of the probable causes of phenotypic differences in cells with identical genomes. However, the microscopic origin of noisy dynamics in RNA production remains unclear. We developed a thermodynamically-consistent mechano-chemical stochastic model, which, via explicit calculations of dynamic properties, provides a consistent physical-chemical description of how the supercoiling of DNA together with enzymatic activity of gyrases produce transcriptional bursting. It also allows us to explain that the coupling between mechanical and chemical processes might be the reason for efficient regulation of transcription.
The hare, tortoise and crocodile revisited: Tree fern facilitation of conifer persistence and angiosperm growth in simulated forests
Authors: Brock James M. R. , Morales Narkis S. , Burns Bruce R. , Perry George L. W. 
Published: October 2019

Abstract

Forests in which conifers and angiosperms coexist in the canopy with a well‐developed understorey/subcanopy have often been conceptualized as three component systems. In these systems, the coexistence and regeneration of the two canopy tree components may be mediated by a third component in the understory and/or subcanopy, for example, palms, bamboo or tree ferns. However, the effect of this understorey/subcanopy component has only been studied over short time periods relative to the longevities (centuries) of the canopy species.

Simulation models provide a way to evaluate the inter‐generational consequences of patterns and mechanisms observed over short temporal extents. We extended a spatially explicit individual‐based simulation model representing the dynamics of New Zealand mixed conifer–angiosperm forest by including a growth form representing tree ferns (the third component). Using model‐based experiments, we evaluated the effects of varying initial densities of tree ferns, the contributions of external propagule sources and the long‐term effects of macro‐litterfall and suppressed seedling density by tree ferns on forest composition and structure over 2,500 years.

The model accurately reproduced observed tree fern growth patterns (height and age distributions) in old‐growth forests, patterns of species replacement and dominance hierarchies in forest succession. The outcomes of the model experiments suggested that shade‐intolerant conifers persist longer and grow older and taller with increasing tree fern density. Although angiosperm stem density reduced along the same series, their longevities and heights also increased with tree fern density. We suggest that these increases are due to conifer and angiosperm trees experiencing reduced competition from neighbouring trees associated with tree ferns increasingly occupying spaces between trees. Over centuries of simulation, the population‐level effect of seedling suppression beneath tree ferns suggests an emergent pattern of negative density dependence in understorey tree ferns.

Synthesis. Tree fern understories are important determinants of forest structure, partially releasing shade‐intolerant conifers from angiosperm competition, reducing angiosperm density and, therefore, competition intensity in northern New Zealand forests. In many forest ecosystems, conifer–angiosperm forest dynamics can be conceptualized as three component systems.
Metabolic syndrome and semen quality in adult population
Authors: Chen Yuan‐Yuei , Kao Tung‐Wei , Peng Tao‐Chun , Yang Hui‐Fang , WU Chen‐Jung , Chen Wei‐Liang 
Published: October 2019

AbstractBackgroundMale obesity is suggested to impact negatively on male fertility and semen quality in numerous studies. However, previous literatures regarding health effects of the metabolic syndrome (MetS) on semen quality are rare and inconsistent. The aim of this study is to investigate the relationship between MetS and sperm parameters in a Taiwanese reproductive‐age male population.MethodsA total of 8395 men who attended a private medical screening program in Taiwan from 2010 to 2016 were included in this cross‐sectional study. Semen analysis was assessed in accordance with the WHO guidelines and included sperm concentration, total motility, progressive motility, and morphology. MetS was defined by the modified National Cholesterol Education Program Third Adult Treatment Panel (NCEP ATP III) criteria with the Asian cutoff for waist circumference (WC). The associations between MetS and semen analysis were examined by multivariable linear regressions.ResultsAfter fully adjusting for pertinent covariables, MetS was significantly associated with a reduced percentage of sperm normal morphology. Blood pressure, WC, and serum glucose had a significantly negative association with sperm normal morphology. Individuals with an increased number of MetS components had a closer association with reduced sperm progressive motility and the percentage of normal morphology.ConclusionMetS and its components exhibited deleterious effects on semen quality among reproductive‐age men. Further studies are warranted to explore these pathophysiologic relationship and underlying mechanisms.
The presence of Aspergillus fumigatus in asthmatic airways is not clearly related to clinical disease severity
Authors: Sullivan Ashley , Hunt Eoin B. , Ward Chris , Lapthorne Susan , Eustace Joseph A. , Fanning Liam J. , Plant Barry J. , O'Byrne Paul M. , MacSharry John A. , Murphy Desmond M. 
Published: October 2019

AbstractBackgroundIt is suggested that airway fungi, in particular Aspergillus may impinge on clinical phenotype in asthma. Indeed, the term severe asthma with fungal sensitization (SAFS) has been coined. We aimed to ascertain whether the presence of fungi, in particular Aspergillus fumigatus, in the airway correlated with asthma severity and control. Furthermore, we aimed to determine whether traditional markers of Aspergillus sensitization related to the presence of Aspergillus within the airway.MethodsSixty‐nine patients characterized by asthma severity (GINA) and level of control (ACQ‐7) underwent bronchoscopy and bronchoalveolar lavage (BAL). Serum was assessed for A fumigatus‐specific IgE and total IgE. Galactomannan and relevant cytokine levels were assessed in serum, plasma and BAL. BAL was analyzed for the presence of A fumigatus.ResultsIn BAL, fungi were visible by microscopy in 70% and present by qPCR in 86% of patients, while A fumigatus was detectable by qPCR in 46%. Plasma and BAL IL‐4, IL‐6, IL‐10, IL‐13 and TNF‐α correlated with BAL fungal presence, while plasma IL‐17 correlated with BAL fungal presence. Aspergillus positive BAL correlated with increased plasma and BAL IL‐6 and BAL IL‐13. There was no relationship between fungal airway presence and steroid dose, asthma severity or control. The presence of Aspergillus within the airway did not relate to serum IgE positivity for Aspergillus.ConclusionsFungi were present in a large proportion of our asthmatic patients’ airways, but their presence was not predicted by traditional markers of sensitization, nor did it appear to be related to measures of disease severity or control.
PGC‐1α plays a pivotal role in simvastatin‐induced exercise impairment in mice
Authors: Panajatovic Miljenko Valentin , Singh François , Roos Noëmi Johanna , Duthaler Urs , Handschin Christoph , Krähenbühl Stephan , Bouitbir Jamal 
Published: October 2019

AbstractAimStatins decrease cardiovascular complications, but can induce myopathy. Here, we explored the implication of PGC‐1α in statin‐associated myotoxicity.MethodsWe treated PGC‐1α knockout (KO), PGC‐1α overexpression (OE) and wild‐type (WT) mice orally with 5 mg simvastatin kg−1 day−1 for 3 weeks and assessed muscle function and metabolism.ResultsIn WT and KO mice, but not in OE mice, simvastatin decreased grip strength, maximal running distance and vertical power assessed by ergometry. Post‐exercise plasma lactate concentrations were higher in WT and KO compared to OE mice. In glycolytic gastrocnemius, simvastatin decreased mitochondrial respiration, increased mitochondrial ROS production and free radical leak in WT and KO, but not in OE mice. Simvastatin increased mRNA expression of Sod1 and Sod2 in glycolytic and oxidative gastrocnemius of WT, but decreased it in KO mice. OE mice had a higher mitochondrial DNA content in both gastrocnemius than WT or KO mice and simvastatin exhibited a trend to decrease the citrate synthase activity in white and red gastrocnemius in all treatment groups. Simvastatin showed a trend to decrease the mitochondrial volume fraction in both muscle types of all treatment groups. Mitochondria were smaller in WT and KO compared to OE mice and simvastatin further reduced the mitochondrial size in WT and KO mice, but not in OE mice.ConclusionsSimvastatin impairs skeletal muscle function, muscle oxidative metabolism and mitochondrial morphology preferentially in WT and KO mice, whereas OE mice appear to be protected, suggesting a role of PGC‐1α in preventing simvastatin‐associated myotoxicity.
Clinicopathologic and immunophenotypic characterization of lichen planopilaris and central centrifugal cicatricial alopecia: A comparative study of 51 cases
Authors: Jordan Christian S. , Chapman Cindi , Kolivras Athanassios , Roberts Janet L. , Thompson Nathaniel B. , Thompson Curtis T. 
Published: October 2019

AbstractBackgroundThe purpose of the study was to compare the histopathologic and immunophenotypic features of central centrifugal cicatricial alopecia (CCCA) and lichen planopilaris (LPP) to better characterize and differentiate these two clinical entities. CCCA remains an ill‐defined and still‐unsettled histologic entity and many hair loss experts regard CCCA to be histologically indistinguishable from LPP. Given the overlapping histologic features of these two lymphocyte‐predominant cicatricial alopecias, and the lack of consensus regarding the significance of proposed distinctions, dermatopathologists face difficulty in providing clinicians and patients certainty with a definitive diagnosis of CCCA vs LPP.MethodsWe performed a retrospective review of 51 scalp biopsies of patients with either the clinical diagnosis of CCCA (27 cases) or LPP (24 cases). Clinical information, histologic features of hematoxylin‐eosin‐stained sections, and a panel of immunohistochemical markers were evaluated on scalp biopsies. Tested parameters were quantified, and statistical analysis was performed.ResultsOur study found no differences on either histologic assessment or immunophenotypic characterization between cases of classic LPP and CCCA.ConclusionThe conclusion of this study is that the inflammatory infiltrates in CCCA and LPP are not only histologically similar but also immunophenotypically indistinguishable.
A major facilitator superfamily transporter in Colletotrichum fructicola (CfMfs1) is required for sugar transport, appressorial turgor pressure, conidiation and pathogenicity
Authors: Chen Yanying , Zhou Guoying , Liu Junang 
Published: October 2019

AbstractThe major facilitator superfamily (MFS) is one of the largest membrane‐protein families. To investigate the role of MFS proteins in the fungal plant anthracnose pathogen Colletotrichum fructicola, the CfMFS1 gene was deleted. This resulted in reduced mycelial growth, conidial yield and decreased virulence on tea oil camellia leaves. In addition, ∆Cfmfs1 showed increased sensitivity to osmotic stress and to a cell‐wall stressor. Further analysis revealed that CfMfs1 is required for conidial penetration and appressorial turgor pressure, both important for fungal pathogen invasion. Confocal fluorescence microscopy showed that CfMfs1 is localized to membranes of both hyphae and conidia, suggesting that it may be a membrane transporter. Our study provides evidence that CfMfs1 has a role in conidiation, sugar transport, stress response, conidial penetration, appressorial turgor pressure and virulence against tea oil camellia.