bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanistic insight into the ribosome biogenesis functions of the ancient protein KsgA
Authors: Connolly Keith , Rife Jason P. , Culver Gloria 
Published: October 2008

SummaryWhile the general blueprint of ribosome biogenesis is evolutionarily conserved, most details have diverged considerably. A striking exception to this divergence is the universally conserved KsgA/Dim1p enzyme family, which modifies two adjacent adenosines in the terminal helix of small subunit ribosomal RNA (rRNA). While localization of KsgA on 30S subunits [small ribosomal subunits (SSUs)] and genetic interaction data have suggested that KsgA acts as a ribosome biogenesis factor, mechanistic details and a rationale for its extreme conservation are still lacking. To begin to address these questions we have characterized the function of Escherichia coli KsgA in vivo using both a ksgA deletion strain and a methyltransferase‐deficient form of this protein. Our data reveal cold sensitivity and altered ribosomal profiles are associated with a ΔksgA genotype in E. coli. Our work also indicates that loss of KsgA alters 16S rRNA processing. These findings allow KsgAs role in SSU biogenesis to be integrated into the network of other identified factors. Moreover, a methyltransferase‐inactive form of KsgA, which we show to be deleterious to cell growth, profoundly impairs ribosome biogenesis‐prompting discussion of KsgA as a possible antimicrobial drug target. These unexpected data suggest that methylation is a second layer of function for KsgA and that its critical role is as a supervisor of biogenesis of SSUs in vivo. These new findings and this proposed regulatory role offer a mechanistic explanation for the extreme conservation of the KsgA/Dim1p enzyme family.
Photosynthesis affects following night leaf conductance in Vicia faba
Authors: EASLON HSIEN MING , RICHARDS JAMES H. 
Published: October 2008

ABSTRACTNight‐time stomatal opening in C3 plants may result in significant water loss when no carbon gain is possible. The objective of this study was to determine if endogenous patterns of night‐time stomatal opening, as reflected in leaf conductance, in Vicia faba are affected by photosynthetic conditions the previous day. Reducing photosynthesis with low light or low CO2 resulted in reduced night‐time stomatal opening the following night, irrespective of the effects on daytime stomatal conductance. Likewise, increasing photosynthesis with enriched CO2 levels resulted in increased night‐time stomatal opening the following night. Reduced night‐time stomatal opening was not the result of an inability to regulate stomatal aperture as leaves with reduced night‐time stomatal opening were capable of greater night‐time opening when exposed to low CO2. After acclimating plants to long or short days, it was found that night‐time leaf conductance was greater in plants acclimated to short days, and associated with greater leaf starch and nitrate accumulation, both of which may affect night‐time guard cell osmotic potential. Direct measurement of guard cell contents during endogenous night‐time stomatal opening will help identify the mechanism of the effect of daytime photosynthesis on subsequent night‐time stomatal regulation.
Defining hybrid poplar (Populus deltoides × Populus trichocarpa) tolerance to ozone: identifying key parameters
Authors: RYAN A. , COJOCARIU C. , POSSELL M. , DAVIES W. J. , HEWITT C. N. 
Published: October 2008

ABSTRACTThis study examined whether two genotypes of hybrid poplar (Populus deltoides × Populus trichocarpa), previously classified as ozone tolerant and ozone sensitive, had differing physiological and biochemical responses when fumigated with 120 nL L−1 ozone for 6 h per day for eight consecutive days. Isoprene emission rate, ozone uptake and a number of physiological and biochemical parameters were investigated before, during and after fumigation with ozone. Previous studies have shown that isoprene protects plants against oxidative stress. Therefore, it was hypothesized that these two genotypes would differ in either their basal isoprene emission rates or in the response of isoprene to fumigation by ozone.Our results showed that the basal emission rates of isoprene, physiological responses and ozone uptake rates were all similar. However, significant differences were found in visible damage, carotenoids, hydrogen peroxide (H2O2), thiobarbituric acid reactions (TBARS) and post‐fumigation isoprene emission rates. It is shown that, although the classification of ozone tolerance or sensitivity had been previously clearly and carefully defined using one particular set of parameters, assessment of other key variables does not necessarily lead to the same conclusions. Thus, it may be necessary to reconsider the way in which plants are classified as ozone tolerant or sensitive.
Metabolome and water status phenotyping of Arabidopsis under abiotic stress cues reveals new insight into ESK1 function
Authors: LUGAN RAPHAEL , NIOGRET MARIE‐FRANÇOISE , KERVAZO LUCIE , LARHER FRANÇOIS ROBERT , KOPKA JOACHIM , BOUCHEREAU ALAIN 
Published: October 2008

ABSTRACTMetabolomic investigation of the freezing‐tolerant Arabidopsis mutant esk1 revealed large alterations in polar metabolite content in roots and shoots. Stress metabolic markers were found to be among the most significant metabolic markers associated with the mutation, but also compounds related to growth regulation or nutrition. The metabolic phenotype of esk1 was also compared to that of wild type (WT) under various environmental constraints, namely cold, salinity and dehydration. The mutant was shown to express constitutively a subset of metabolic responses which fits with the core of stress metabolic responses in the WT. But remarkably, the most specific metabolic responses to cold acclimation were not phenocopied by esk1 mutation and remained fully inducible in the mutant at low temperature. Under salt stress, esk1 accumulated lower amounts of Na+ in leaves than the WT, and under dehydration stress its metabolic profile and osmotic potential were only slightly impacted. These phenotypes are consistent with the hypothesis of an altered water status in esk1, which actually exhibited basic lower water content (WC) and transpiration rate (TR) than the WT. Taken together, the results suggest that ESK1 does not function as a specific cold acclimation gene, but could rather be involved in water homeostasis.
A putative lipase gene EXTRA GLUME1 regulates both empty‐glume fate and spikelet development in rice
Authors: Li Haoge , Xue Dawei , Gao Zhenyu , Yan Meixian , Xu Wenying , Xing Zhuo , Huang Danian , Qian Qian , Xue Yongbiao 
Published: October 2008

SummaryRecent studies have shown that molecular control of inner floral organ identity appears to be largely conserved between monocots and dicots, but little is known regarding the molecular mechanism underlying development of the monocot outer floral organ, a unique floral structure in grasses. In this study, we report the cloning of the rice EXTRA GLUME1 (EG1) gene, a putative lipase gene that specifies empty‐glume fate and floral meristem determinacy. In addition to affecting the identity and number of empty glumes, mutations in EG1 caused ectopic floral organs to be formed at each organ whorl or in extra ectopic whorls. Iterative glume‐like structures or new floral organ primordia were formed in the presumptive region of the carpel, resulting in an indeterminate floral meristem. EG1 is expressed strongly in inflorescence primordia and weakly in developing floral primordia. We also found that the floral meristem and organ identity gene OsLHS1 showed altered expression with respect to both pattern and levels in the eg1 mutant, and is probably responsible for the pleiotropic floral defects in eg1. As a putative class III lipase that functionally differs from any known plant lipase, EG1 reveals a novel pathway that regulates rice empty‐glume fate and spikelet development.
Pluripotency of Arabidopsis xylem pericycle underlies shoot regeneration from root and hypocotyl explants grown in vitro
Authors: Atta Ramzy , Laurens Lieve , Boucheron‐Dubuisson Elodie , Guivarc’h Anne , Carnero Eugénie , Giraudat‐Pautot Véronique , Rech Philippe , Chriqui Dominique 
Published: October 2008

SummaryWe have established a detailed framework for the process of shoot regeneration from Arabidopsis root and hypocotyl explants grown in vitro. Using transgenic plant lines in which the GUS or GFP genes were fused to promoters of developmental genes (WUS, CLV1, CLV3, STM, CUC1, PLT1, RCH1, QC25), or to promoters of genes encoding indicators of the auxin response (DR5) or transport (PIN1), cytokinin (CK) response (ARR5) or synthesis (IPT5), or mitotic activity (CYCB1), we showed that regenerated shoots originated directly or indirectly from the pericycle cells adjacent to xylem poles. In addition, shoot regeneration appeared to be partly similar to the formation of lateral root meristems (LRMs). During pre‐culture on a 2, 4‐dichlorophenoxyacetic acid (2, 4‐D)‐rich callus‐inducing medium (CIM), xylem pericycle reactivation established outgrowths that were not true calli but had many characteristics of LRMs. Transfer to a CK‐rich shoot‐inducing medium (SIM) resulted in early LRM‐like primordia changing to shoot meristems. Direct origin of shoots from the xylem pericycle occurred upon direct culture on CK‐containing media without prior growth on CIM. Thus, it appeared that the xylem pericycle is more pluripotent than previously thought. This pluripotency was accompanied by the ability of pericycle derivatives to retain diploidy, even after several rounds of cell division. In contrast, the phloem pericycle did not display such developmental plasticity, and responded to CKs with only periclinal divisions. Such observations reinforce the view that the pericycle is an ‘extended meristem’ that comprises two types of cell populations. They also suggest that the founder cells for LRM initiation are not initially fully specified for this developmental pathway.
Quality of antenatal and delivery care before and after the implementation of a prevention of mother‐to‐child HIV transmission programme in Côte d’Ivoire
Authors: Delvaux Thérèse , Diby Konan Jean‐Paul , Aké‐Tano Odile , Gohou‐Kouassi Valérie , Bosso Patrice Emery , Buvé Anne , Ronsmans Carine 
Published: October 2008

SummaryObjective  To assess whether implementation of a prevention of mother‐to‐child HIV transmission (PMTCT) programme in Côte d’Ivoire improved the quality of antenatal and delivery care services.Methods  Quality of antenatal and delivery care services was assessed in five urban health facilities before (2002–2003) and after (2005) the implementation of a PMTCT programme through review of facility data; observation of antenatal consultations (n = 606 before; n = 591 after) and deliveries (n = 229 before; n = 231 after) and exit interviews of women; and interviews of health facility staff.Results  HIV testing was never proposed at baseline and was proposed to 63% of women at the first ANC visit after PMTCT implementation. The overall testing rate was 42% and 83% of tested HIV‐infected pregnant women received nevirapine. In addition, inter‐personal communication and confidentiality significantly improved in all health facilities. In the maternity ward, quality of obstetrical care at admission, delivery and post‐partum care globally improved in all facilities after the implementation of the programme although some indicators remained poor, such as filling in the partograph directly during labour. Episiotomy rates among primiparous women dropped from 64% to 25% (P < 0.001) after PMTCT implementation. Global scores for quality of antenatal and delivery care significantly improved in all facilities after the implementation of the programme.Conclusions  Introducing comprehensive PMTCT services can improve the quality of antenatal and delivery care in general.
Can VISION 2020 be implemented in rural government settings? Findings from two programmes in Tanzania
Authors: Eliah Edson , Shayo Andrew , Gendo Charles , Courtright Paul , Theraney Manisha , Lewallen Susan 
Published: October 2008

SummaryObjective  To generate information on essential components and the cost recovery potential of VISION 2020 programmes in rural Africa.Methods  We took a structured approach to planning, training, implementation and supervision of programmes in Singida and Mara regions, Tanzania involving both government and non‐government partners. Extensive mentoring was provided to monitor activities and costs.Results  Annual numbers of patients receiving eye care increased sevenfold, cataract surgeries by a factor of 2.6 and spectacles dispensed by a factor of 16. Running costs were shared; the government provided 40–60%, non‐government organisations (NGOs) 25–45%, and patient fees 15%.Conclusion  Comprehensive eye care can be delivered with cooperation among partners. However, continued coordination and cooperation from government and NGOs are critical to reach VISION 2020 goals.
Occurrence, productivity and spatial distribution of key‐premises in two dengue‐endemic areas of Rio de Janeiro and their role in adult Aedes aegypti spatial infestation pattern
Authors: Maciel‐de‐Freitas Rafael , Peres Roberto C. , Souza‐Santos Reinaldo , Lourenço‐de‐Oliveira Ricardo 
Published: October 2008

SummaryObjectives  To evaluate: (1) the occurrence, maintenance, productivity, spatial distribution and premise condition index score of Adese aegypti‐infested houses and key‐premises in a suburban district (Tubiacanga) and a slum (Favela do Amorim) of Rio de Janeiro and (2) the role of these factors in adult Ae. aegypti female spatial distribution.Methods and Results  A total of 2456 premises were inspected for immature and 1100 for adult collection. Key‐premises corresponded to 16.08% and 17.86% of infested houses in Tubiacanga, and 13.5% and 11.1% in Favela do Amorim, during the dry and wet seasons, respectively. Key‐premises held significantly more immature Ae. aegypti, pupae and larvae than infested houses in Favela do Amorim and Tubiacanga during the dry and wet seasons. In Favela do Amorim, key‐premises had a significantly higher PCI score than infested but non‐key houses.Conclusion  The spatial distribution of key‐premises and adult Ae. aegypti females was often congruent, indicating that key‐premises influence the infestation pattern observed in the study areas.
Blue–Green Eggs in Pied Flycatchers: An Experimental Demonstration that a Supernormal Stimulus Elicits Improved Nestling Condition
Authors: Moreno Juan , Lobato Elisa , Merino Santiago , Martínez‐de la Puente Josué 
Published: October 2008

AbstractIt has been proposed that blue–green egg colouration in certain avian species has evolved as a signal of female and egg quality to males, affecting their investment in the brood according to the differential allocation scenario. A recent experiment has successfully manipulated male investment by placing dummy eggs simulating the extremes in the blue–green natural reflectance. Here we have substituted one egg in certain pied flycatcher clutches with a single deep‐blue (blue) or light‐blue (pale) dummy egg and used other clutches as controls. Blue dummy eggs reflected more in the blue–green part of the spectrum than natural and pale dummy eggs, which were similar in reflectance. Nestlings in nests with one blue dummy egg during laying and incubation attained a significantly higher mass and condition than those in nests with one pale dummy egg or in control broods, when controlling for phenology, brood size and blue–green chroma of the clutch. Only a shift in parental investment can have induced this highly significant effect. Preference for deeply coloured clutches associated with high‐quality females and their maternal effects may explain stimulation by a single supernormal stimulus emanating from multiple objects like clutches.
Postural Shifts During Egg‐Brooding and Their Impact on Egg Water Balance in Children’s Pythons (Antaresia childreni)
Authors: Stahlschmidt Zachary R. , Hoffman Ty C. M. , DeNardo Dale F. 
Published: October 2008

AbstractParental care typically consists of distinct behavioral components that are balanced to address the multiple needs of offspring. Female pythons exhibit post‐oviposition parental care in which they coil around their parchment‐shelled eggs throughout incubation (40–80 d). Subtle postural shifts during egg‐brooding facilitate embryonic gas exchange but may entail hydric costs to the clutch. This study used a simple behavioral model to (1) further quantify the costs and benefits of specific parental behaviors to developing offspring and (2) determine the influence that developmental stage and relative clutch mass have on parental behavior. Although previous research has demonstrated that egg‐brooding as a whole reduces clutch water loss, we hypothesized that egg‐brooding female pythons specifically adopt a tightly coiled posture to conserve embryonic water, but must make postural adjustments to enhance gas exchange between the clutch and nest environments at the cost of increased clutch water loss. We measured rates of water loss in brooding Children’s pythons (Antaresia childreni) and their respective clutches (i.e., brooding units) and monitored changes in brooding posture. We conducted serial trials to elucidate the effect of developmental stage on postural adjustments and water loss. Results demonstrated that the proportion of time females spent in a tightly coiled posture was inversely related to mean water loss from the brooding unit. Analyses indicated that slight adjustments in posture led to bursts in brooding unit water loss. Indeed, brooding unit water loss during postural adjustments was significantly higher than during tight coiling. These findings imply that python egg‐brooding provides an adjustable diffusive barrier that leads to discontinuous gas exchange, which minimizes clutch water loss. Because females with larger relative clutch masses spent more time tightly coiled, egg‐brooding female pythons may use a ‘water first’ strategy in which they intentionally conserve clutch water at the cost of reduced embryonic respiratory gas exchange.
Body Mass and not Wing Length Predicts Territorial Success in a Tropical Satyrine Butterfly
Authors: Peixoto Paulo Enrique Cardoso , Benson Woodruff W. 
Published: October 2008

AbstractThe males of numerous butterfly species fight with conspecific rivals to possess mating territories. Although there is little consensus on the nature of fight costs or on what traits favor victory, a recent analysis suggests that size may be of minor importance. However, data are inconsistent, and wing length, the metric that has been most widely used for expressing size in butterfly field studies, may not provide a reliable index of muscle mass or other traits that determine resource holding potential. Here we investigate the influence of wing length, body mass and wing wear on the territorial success of a neotropical satryine butterfly, Paryphthimoides phronius. In a removal experiment, original residents were heavier than replacement males that took over territories in the following minutes. Winners of naturally occurring contests were also heavier than losers after correcting for weight loss since weighing. Although wing length correlated significantly with body mass and body mass decreased with age, neither wing length nor wing wear (a surrogate for age and body condition) contributed to explaining territorial success. As body mass may be related to traits such as muscle mass, fat stores, and age, no conclusion is possible on how mass translates into success in disputes. However, because wing length is unrelated to residency status in P. phronius, whereas mass is both a reliable predictor and performs significantly better than wing length, our results may help explain the frequent failure of wing length to predict territorial success in butterfly field studies.
Why are Male Columbian Ground Squirrels Territorial?
Authors: Manno Theodore G. , Stephen Dobson F. 
Published: October 2008

AbstractMale territorial defence is a component of many vertebrate mating systems and is often regarded as a tactic for acquiring mates. Traditionally considered within the context of overt site‐specific defence, territoriality actually may have several components which encompass a variety of behavioural tactics (e.g. post‐copulatory mate‐guarding, defence of resources that females need, defence of area around females) that underlie a mating system. The purpose of our study was to evaluate such influences on the territorial behaviour of male Columbian ground squirrels in southwestern Alberta, Canada. Males were dominant and territorial if they defended a minimum convex polygon activity range by chasing other males more within the activity range than they were chased. Subordinate males had no territory and were chased throughout their ranges, but they competed for mates by increasing chases in their activity range when nearby females were oestrous. Dominant males exhibited conditional breeding tactics, tending to chase other dominant males from their territory when nearby females were oestrous, but travelling outside their activity ranges to chase subordinate males when females were not oestrous. Although females mated first with a dominant male on whose territory they resided (and in order from oldest to youngest if several territories overlapped), mating pairs were not exclusive, as females usually mated with additional males. Males also guarded females after copulation and defended females directly just before oestrus, rather than defending territoryper seduring those times. Thus, males possess a repertoire of behaviours that complement site‐specific territoriality, and territory ownership serves to facilitate a first mating with females that live on the territory.
Olfactory Predator Discrimination in Yellow‐Bellied Marmots
Authors: Blumstein Daniel T. , Barrow Lisa , Luterra Markael 
Published: October 2008

AbstractThe mechanism underlying olfactory predator identification may be relatively experience‐independent, or it may rely on specific experience with predators. A mechanism by which prey might identify novel predators relies on the inevitable creation of sulfurous metabolites that are then excreted in the urine of carnivorous mammals. We tested whether free‐living, yellow‐bellied marmots (Marmota flaviventris) and mid‐sized herbivores that fall prey to a variety of carnivorous mammals could discriminate herbivore (elk—Cervus elephas) urine from predator (red fox—Vulpes vulpes, coyote—Canis latrans, mountain lion—Felis concolor, wolf—Canis lupus) urine, a novel herbivore (moose—Alces alces), and a distilled water control. We further asked how specific this assessment was by testing whether marmots responded differently to predators representing different levels of risk and to familiar vs. unfamiliar predators. We found that marmots responded more to urine from coyotes (a familiar predator on adults), mountain lions (a potentially unfamiliar predator that could kill adults) and wolves (a locally extinct predator that could kill adults) than to elk urine (a non‐predator). Red fox (a predator that poses a risk only to recently emerged marmot pups) urine elicited a less substantial (but not significantly so) response than coyote urine. Marmots can identify predators, even novel ones, using olfactory cues, suggesting that experience with a specific predator is not required to identify potential threats.