bluuebunny/crossref_metadata_2025_split huggingface dataset:
Niche shifts and range expansions along cordilleras drove diversification in a high‐elevation endemic plant genus in the tropical Andes
Authors: Kolář Filip , Dušková Eva , Sklenář Petr 
Published: August 2016

AbstractThe tropical Andes represent one of the world's biodiversity hot spots, but the evolutionary drivers generating their striking species diversity still remain poorly understood. In the treeless high‐elevation Andean environments, Pleistocene glacial oscillations and niche differentiation are frequently hypothesized diversification mechanisms; however, sufficiently densely sampled population genetic data supporting this are still lacking. Here, we reconstruct the evolutionary history ofLoricaria(Asteraceae), a plant genus endemic to the Andean treeless alpine zone, based on comprehensive population‐level sampling of 289 individuals from 67 populations across the entire distribution ranges of its northern Andean species. Partly incongruent AFLP and plastid DNA markers reveal that the distinct genetic structure was shaped by a complex interplay of biogeography (spread along and across the cordilleras), history (Pleistocene glacial oscillations) and local ecological conditions. While plastid variation documents an early split or colonization of the northern Andes by at least two lineages, one of which further diversified, a major split in the AFLP data correlate with altitudinal ecological differentiation. This suggests that niche shifts may be important drivers of Andean diversification not only in forest–alpine transitions, but also within the treeless alpine zone itself. The patterns of genetic differentiation at the intraspecific level reject the hypothesized separation in spatially isolated cordilleras and instead suggest extensive gene flow among populations from distinct mountain chains. Our study highlights that leveraging highly variable markers against extensive population‐level sampling is a promising approach to address mechanisms of rapid species diversifications.
Mechanisms of mast seeding: resources, weather, cues, and selection
Authors: Pearse Ian S. , Koenig Walter D. , Kelly Dave 
Published: August 2016

SummaryMast seeding is a widespread and widely studied phenomenon. However, the physiological mechanisms that mediate masting events and link them to weather and plant resources are still debated. Here, we explore how masting is affected by plant resource budgets, fruit maturation success, and hormonal coordination of cues including weather and resources. There is little empirical support for the commonly stated hypothesis that plants store carbohydrates over several years to expend in a high‐seed year. Plants can switch carbohydrates away from growth in high‐seed years, and seed crops are more probably limited by nitrogen or phosphorus. Resources are clearly involved in the proximate mechanisms driving masting, but resource budget (RB) models cannot create masting in the absence of selection because some underlying selective benefit is required to set the level of a ‘full’ seed crop at greater than the annual resource increment. Economies of scale (EOSs) provide the ultimate factor selecting for masting, but EOSs probably always interact with resources, which modify the relationship between weather cues and reproduction. Thus, RB and EOS models are not alternative explanations for masting – both are required. Experiments manipulating processes that affect mast seeding will help clarify the physiological mechanisms that underlie mast seeding.

Contents

Summary
546

I.
Introduction
546

II.
Ultimate and proximate hypotheses for masting behaviour
547

III.
The role of plant resources in masting
548

IV.
Which resources limit seed set?
552

V.
Pollination, fruit development, and masting
554

VI.
Hormonal control of seed set and masting
556

VII.
Evolutionary perspectives on masting behaviour
558

VIII.
Unifying resource budget and economy of scale models of masting
558

IX.
Conclusions
559

Acknowledgements
559

References
559
Deletion of FtsH11 protease has impact on chloroplast structure and function in Arabidopsis thaliana when grown under continuous light
Authors: Wagner Raik , von Sydow Lotta , Aigner Harald , Netotea Sergiu , Brugière Sabine , Sjögren Lars , Ferro Myriam , Clarke Adrian , Funk Christiane 
Published: August 2016

AbstractThe membrane‐integrated metalloprotease FtsH11 of Arabidopsis thaliana is proposed to be dual‐targeted to mitochondria and chloroplasts. A bleached phenotype was observed in ftsh11 grown at long days or continuous light, pointing to disturbances in the chloroplast. Within the chloroplast, FtsH11 was found to be located exclusively in the envelope. Two chloroplast‐located proteins of unknown function (Tic22‐like protein and YGGT‐A) showed significantly higher abundance in envelope membranes and intact chloroplasts of ftsh11 and therefore qualify as potential substrates for the FtsH11 protease. No proteomic changes were observed in the mitochondria of 6‐week‐old ftsh11 compared with wild type, and FtsH11 was not immunodetected in these organelles. The abundance of plastidic proteins, especially of photosynthetic proteins, was altered even during standard growth conditions in total leaves of ftsh11. At continuous light, the amount of photosystem I decreased relative to photosystem II, accompanied by a drastic change of the chloroplast morphology and a drop of non‐photochemical quenching. FtsH11 is crucial for chloroplast structure and function during growth in prolonged photoperiod.
Function of Sitka spruce stone cells as a physical defence against white pine weevil
Authors: Whitehill Justin G. A. , Henderson Hannah , Strong Ward , Jaquish Barry , Bohlmann Jörg 
Published: August 2016

AbstractStone cells are a physical defence of conifers against stem feeding insects such as weevils and bark beetles. In Sitka spruce, abundance of stone cells in the cortex of apical shoot tips is associated with resistance to white pine weevil. However, the mode of action by which stone cells interfere with growth and development of weevil larvae is unknown. We developed a bioassay system for testing potential effects of stone cells, which were isolated from resistant trees, on weevil larvae. Bioassays using artificial diet and controlled amounts of stone cells focused on physical defence. We evaluated the effects of stone cells on establishment of neonate larvae, mandible wear and changes in relative growth rates of third instar larvae. Establishment of neonates and relative growth rates of third instars were significantly reduced by stone cells. Stone cells appeared to be indigestible by weevil larvae. Our results suggest that stone cells affect weevil establishment and development by forming a physical feeding barrier against neonate larvae at the site of oviposition, and by reducing access to nutrients in the cortex of resistant trees, which contain an abundance of stone cells in place of a more nutrient rich tissue in susceptible trees.
Does intrinsic motivation enhance motor cortex excitability?
Authors: Radel Rémi , Pjevac Dusan , Davranche Karen , d'Arripe‐Longueville Fabienne , Colson Serge S. , Lapole Thomas , Gruet Mathieu 
Published: August 2016

AbstractIntrinsic motivation (IM) is often viewed as a spontaneous tendency for action. Recent behavioral and neuroimaging evidence indicate that IM, in comparison to extrinsic motivation (EM), solicits the motor system. Accordingly, we tested whether IM leads to greater excitability of the motor cortex than EM. To test this hypothesis, we used two different tasks to induce the motivational orientation using either words representing each motivational orientation or pictures previously linked to each motivational orientation through associative learning. Single‐pulse transcranial magnetic stimulation over the motor cortex was applied when viewing the stimuli. Electromyographic activity was recorded on the contracted first dorsal interosseous muscle. Two indexes of corticospinal excitability (the amplitude of motor‐evoked potential and the length of cortical silent period) were obtained through unbiased automatic detection and analyzed using a mixed model that provided both statistical power and a high level of control over all important individual, task, and stimuli characteristics. Across the two tasks and the two indices of corticospinal excitability, the exposure to IM‐related stimuli did not lead to a greater corticospinal excitability than EM‐related stimuli or than stimuli with no motivational valence (ps > .20). While these results tend to dismiss the advantage of IM at activating the motor cortex, we suggest alternative hypotheses to explain this lack of effect, which deserves further research.
Toward the influence of temporal attention on the selection of targets in a visual search task: An ERP study
Authors: Rolke Bettina , Festl Freya , Seibold Verena C. 
Published: August 2016

AbstractWe used ERPs to investigate whether temporal attention interacts with spatial attention and feature‐based attention to enhance visual processing. We presented a visual search display containing one singleton stimulus among a set of homogenous distractors. Participants were asked to respond only to target singletons of a particular color and shape that were presented in an attended spatial position. We manipulated temporal attention by presenting a warning signal before each search display and varying the foreperiod (FP) between the warning signal and the search display in a blocked manner. We observed distinctive ERP effects of both spatial and temporal attention. The amplitudes for the N2pc, SPCN, and P3 were enhanced by spatial attention indicating a processing benefit of relevant stimulus features at the attended side. Temporal attention accelerated stimulus processing; this was indexed by an earlier onset of the N2pc component and a reduction in reaction times to targets. Most importantly, temporal attention did not interact with spatial attention or stimulus features to influence visual processing. Taken together, the results suggest that temporal attention fosters visual perceptual processing in a visual search task independently from spatial attention and feature‐based attention; this provides support for the nonspecific enhancement hypothesis of temporal attention.
Aquaculture of marine non‐food organisms: what, why and how?
Authors: Leal Miguel Costa , Rocha Rui Jorge Miranda , Rosa Rui , Calado Ricardo 
Published: August 2016

AbstractAquaculture is among the fastest growing industries in the world and the fastest in the food production sector. However, not all aquaculture organisms are produced for human consumption. Indeed, an important fraction of aquaculture products target a wide variety of applications, from pharmaceutical, cosmeceutical, ornamental and nutraceutical applications, as well as biofuel production, conservation efforts and academic purposes, among others. Despite the increasing importance of aquaculture for non‐food purposes, a comprehensive review covering the state of the art of this topic, its latest developments and future trends is missing. Here, we review what marine organisms are produced for non‐food purposes, as well as why and how they are produced. Instead of providing a thorough methodological review, production protocols are briefly summarized and an updated guide to the most relevant literature is provided. We overview current developments driving the aquaculture of non‐food organisms, underpin their most significant applications and highlight future prospects for non‐food aquaculture.
Poly-
N
-Acetylglucosamine Production by Staphylococcus epidermidis Cells Increases Their
In Vivo
Proinflammatory Effect
Authors: Ferreirinha Pedro , Pérez-Cabezas Begoña , Correia Alexandra , Miyazawa Bruna , França Angela , Carvalhais Virgínia , Faustino Augusto , Cordeiro-da-Silva Anabela , Teixeira Luzia , Pier Gerald B. , Cerca Nuno , Vilanova Manuel 
Published: August 2016

ABSTRACT

Poly-
N
-acetylglucosamine (PNAG) is a major component of the
Staphylococcus epidermidis
biofilm extracellular matrix. However, it is not yet clear how this polysaccharide impacts the host immune response and infection-associated pathology. Faster neutrophil recruitment and bacterial clearance were observed in mice challenged intraperitoneally with
S. epidermidis
biofilm cells of the PNAG-producing 9142 strain than in mice similarly challenged with the isogenic PNAG-defective M10 mutant. Moreover, intraperitoneal priming with 9142 cells exacerbated liver inflammatory pathology induced by a subsequent intravenous
S. epidermidis
challenge, compared to priming with M10 cells. The 9142-primed mice had elevated splenic CD4
+
T cells producing gamma interferon and interleukin-17A, indicating that PNAG promoted cell-mediated immunity. Curiously, despite having more marked liver tissue pathology, 9142-primed mice also had splenic T regulatory cells with greater suppressive activity than those of their M10-primed counterparts. By showing that PNAG production by
S. epidermidis
biofilm cells exacerbates host inflammatory pathology, these results together suggest that this polysaccharide contributes to the clinical features associated with biofilm-derived infections.
Experimental Evidence of Bacterial Colonization of Human Coronary Microvasculature and Myocardial Tissue during Meningococcemia
Authors: Bergounioux Jean , Coureuil Mathieu , Belli Emre , Ly Mohamed , Cambillau Michelle , Goudin Nicolas , Nassif Xavier , Join-Lambert Olivier 
Published: August 2016

ABSTRACT

Meningococcal septic shock is associated with profound vasoplegia, early and severe myocardial dysfunction, and extended skin necrosis responsible for a specific clinical entity designated purpura fulminans (PF). PF represents 90% of fatal meningococcal infections. One characteristic of meningococcal PF is the myocardial dysfunction that occurs in the early phase of sepsis. Furthermore, hemodynamic studies have shown that the prognosis of meningococcal sepsis is directly related to the degree of impairment of cardiac contractility during the initial phase of the disease. To gain insight into a potential interaction of
Neisseria meningitidis
with the myocardial microvasculature, we modified a previously described humanized mouse model by grafting human myocardial tissue to SCID mice. We then infected the grafted mice with
N. meningitides
. Using the humanized SCID mouse model, we demonstrated that
N. meningitidis
targets the human myocardial tissue vasculature, leading to the formation of blood thrombi, infectious vasculitis, and vascular leakage. These results suggest a novel mechanism of myocardial injury in the course of severe
N. meningitidis
sepsis that is likely to participate in primary myocardial dysfunction.
Z-DNA Binding Protein Mediates Host Control of Toxoplasma gondii Infection
Authors: Pittman Kelly J. , Cervantes Patrick W. , Knoll Laura J. 
Published: August 2016

ABSTRACT

Intrinsic to
Toxoplasma gondii
infection is the parasite-induced modulation of the host immune response, which ensures establishment of a chronic lifelong infection. This manipulation of the host immune response allows
T. gondii
to not only dampen the ability of the host to eliminate the parasite but also trigger parasite differentiation to the slow-growing, encysted bradyzoite form. We previously used RNA sequencing (RNA-seq) to profile the transcriptomes of mice and
T. gondii
during acute and chronic stages of infection. One of the most abundant host transcripts during acute and chronic infection was Z-DNA binding protein 1 (ZBP1). In this study, we determined that ZBP1 functions to control
T. gondii
growth. In activated macrophages isolated from ZBP1 deletion (ZBP1
−/−
) mice,
T. gondii
has an increased rate of replication and a decreased rate of degradation. We also identified a novel function for ZBP1 as a regulator of nitric oxide (NO) production in activated macrophages, even in the absence of
T. gondii
infection. Upon stimulation,
T. gondii
-infected ZBP1
−/−
macrophages display increased proinflammatory cytokines compared to wild-type macrophages under the same conditions. These
in vitro
phenotypes were recapitulated
in vivo
, with ZBP1
−/−
mice having increased susceptibility to oral challenge, higher cyst burdens during chronic infection, and elevated inflammatory cytokine responses. Taken together, these results highlight a role for ZBP1 in assisting host control of
T. gondii
infection.
Unexpected Diversity of Escherichia coli Sialate
O
-Acetyl Esterase NanS
Authors: Rangel Ariel , Steenbergen Susan M. , Vimr Eric R. 
Published: August 2016

ABSTRACT

The sialic acids (
N
-acylneuraminates) are a group of nine-carbon keto-sugars existing mainly as terminal residues on animal glycoprotein and glycolipid carbohydrate chains. Bacterial commensals and pathogens exploit host sialic acids for nutrition, adhesion, or antirecognition, where
N
-acetyl- or
N
-glycolylneuraminic acids are the two predominant chemical forms of sialic acids. Each form may be modified by acetyl esters at carbon position 4, 7, 8, or 9 and by a variety of less-common modifications. Modified sialic acids produce challenges for colonizing bacteria, because the chemical alterations to
N
-acetylneuraminic acid (Neu5Ac) confer increased resistance to sialidase and aldolase activities essential for the catabolism of host sialic acids. Bacteria with
O
-acetyl sialate esterase(s) utilize acetylated sialic acids for growth, thereby gaining a presumed metabolic advantage over competitors lacking this activity. Here, we demonstrate the esterase activity of
Escherichia coli
NanS after purifying it as a C-terminal HaloTag fusion. Using a similar approach, we show that
E. coli
strain O157:H7 Stx prophage or prophage remnants invariably include paralogs of
nanS
often located downstream of the Shiga-like toxin genes. These paralogs may include sequences encoding N- or C-terminal domains of unknown function where the NanS domains can act as sialate
O
-acetyl esterases, as shown by complementation of an
E. coli
strain K-12
nanS
mutant and the unimpaired growth of an
E. coli
O157
nanS
mutant on
O
-acetylated sialic acid. We further demonstrate that
nanS
homologs in
Streptococcus
spp. also encode active esterase, demonstrating an unexpected diversity of bacterial sialate
O
-acetyl esterase.

IMPORTANCE
The sialic acids are a family of over 40 naturally occurring 9-carbon keto-sugars that function in a variety of host-bacterium interactions. These sugars occur primarily as terminal carbohydrate residues on host glycoproteins and glycolipids. Available evidence indicates that diverse bacterial species use host sialic acids for adhesion or as sources of carbon and nitrogen. Our results show that the catabolism of the diacetylated form of host sialic acid requires a specialized esterase, NanS. Our results further show that
nanS
homologs exist in bacteria other than
Escherichia coli
, as well as part of toxigenic
E. coli
prophage. The unexpected diversity of these enzymes suggests new avenues for investigating host-bacterium interactions. Therefore, these original results extend our previous studies of
nanS
to include mucosal pathogens, prophage, and prophage remnants. This expansion of the
nanS
superfamily suggests important, although as-yet-unknown, functions in host-microbe interactions.
Large Sequence Diversity within the Biosynthesis Locus and Common Biochemical Features of Campylobacter coli Lipooligosaccharides
Authors: Culebro Alejandra , Revez Joana , Pascoe Ben , Friedmann Yasmin , Hitchings Matthew D. , Stupak Jacek , Sheppard Samuel K. , Li Jianjun , Rossi Mirko 
Published: August 2016

ABSTRACT

Despite the importance of lipooligosaccharides (LOSs) in the pathogenicity of campylobacteriosis, little is known about the genetic and phenotypic diversity of LOS in
Campylobacter coli
. In this study, we investigated the distribution of LOS locus classes among a large collection of unrelated
C. coli
isolates sampled from several different host species. Furthermore, we paired
C. coli
genomic information and LOS chemical composition for the first time to investigate possible associations between LOS locus class sequence diversity and biochemical heterogeneity. After identifying three new LOS locus classes, only 85% of the 144 isolates tested were assigned to a class, suggesting higher genetic diversity than previously thought. This genetic diversity is at the basis of a completely unexplored LOS structural heterogeneity. Mass spectrometry analysis of the LOSs of nine isolates, representing four different LOS classes, identified two features distinguishing
C. coli
LOS from that of
Campylobacter jejuni
. 2-Amino-2-deoxy-
d
-glucose (GlcN)–GlcN disaccharides were present in the lipid A backbone, in contrast to the β-1′-6-linked 3-diamino-2,3-dideoxy-
d
-glucopyranose (GlcN3N)–GlcN backbone observed in
C. jejuni
. Moreover, despite the fact that many of the genes putatively involved in 3-acylamino-3,6-dideoxy-
d
-glucose (Qui
p
3NAcyl) were apparently absent from the genomes of various isolates, this rare sugar was found in the outer core of all
C. coli
isolates. Therefore, regardless of the high genetic diversity of the LOS biosynthesis locus in
C. coli
, we identified species-specific phenotypic features of
C. coli
LOS that might explain differences between
C. jejuni
and
C. coli
in terms of population dynamics and host adaptation.

IMPORTANCE
Despite the importance of
C. coli
to human health and its controversial role as a causative agent of Guillain-Barré syndrome, little is known about the genetic and phenotypic diversity of
C. coli
LOSs. Therefore, we paired
C. coli
genomic information and LOS chemical composition for the first time to address this paucity of information. We identified two species-specific phenotypic features of
C. coli
LOS, which might contribute to elucidating the reasons behind the differences between
C. jejuni
and
C. coli
in terms of population dynamics and host adaptation.
Groundwater controls on episodic soil erosion and dust emissions in a desert ecosystem
Authors: Kaste J.M. , Elmore A.J. , Vest K.R. , Okin G.S. 
Published: August 2016

Abstract
Feedbacks between vegetation, soils, and sediment transport processes maintain arid landscapes in geomorphically active degraded states or in more biologically productive and geomorphically stable states. Landscape evolution models and resource management strategies require a detailed understanding of thresholds that limit sediment transport in deserts, but it can be difficult to quantify geomorphic responses to abrupt environmental change. Here we use measurements of fallout radionuclides and salt content in soils, horizontal sediment fluxes, vegetation cover, and saturated zone depth in Owens Valley, California (USA), to quantify the geomorphic response of a desert landscape to changes in groundwater availability. Owens Valley has a well-documented history of surface-water diversions and pumping during the A.D. 1987–1992 drought, and we studied 11 sites having a gradient of ∼0.5 m to 8 m of groundwater decline during this time. We show that short-length-scale (&lt;50 m) sediment redistribution is active in areas with a range of environmental histories, but centimeter-scale net soil loss occurred when photosynthetic vegetation cover declined to &lt;20% where local groundwater remained shallow enough to produce evaporite salts. Erosion and dust emissions are most severe in central Owens Valley when groundwater falls below the 2 m effective rooting depth of native meadow vegetation but remains shallow enough (&lt;6 m) so that capillary action maintains loose erodible sediment at the surface.