bluuebunny/crossref_metadata_2025 huggingface dataset:
Mating system, pollen and propagule dispersal, and spatial genetic structure in a high‐density population of the mangrove tree Kandelia candel
Authors: GENG QIFANG , LIAN CHUNLAN , GOTO SUSUMU , TAO JIANMIN , KIMURA MEGUMI , ISLAM MD SAJEDUL , HOGETSU TAIZO
Published: November 2008

Mangrove tree species form ecologically and economically important forests along the tropical and subtropical coastlines of the world. Although low intrapopulation genetic diversity and high interpopulation genetic differentiation have been detected in most mangrove tree species, no direct investigation of pollen and propagule dispersal through paternity and/or parentage analysis and spatial genetic structure within populations has been conducted. We surveyed the mating system, pollen and propagule dispersal, and spatial genetic structure in a natural population of Kandelia candel, one of the typical viviparous mangrove tree species, using nuclear and chloroplast microsatellite markers. High diversity and outcrossing rates were observed. Paternity and parentage analysis and modelling estimations revealed the presence of an extremely short‐distance component of pollen and propagule dispersal (pollen: 15.2 ± 14.9 m (SD) by paternity analysis and 34.4 m by modelling; propagule: 9.4 ± 13.8 m (SD) by parentage analysis, and 18.6 m by modelling). Genetic structure was significant at short distances, and a clumped distribution of chloroplast microsatellite genotypes was seen in K. candel adults. We conclude that the K. candel population was initiated by limited propagule founders from outside by long‐distance dispersal followed by limited propagule dispersal from the founders, resulting in a half‐sib family structure.
Host range expansion of an introduced insect pest through multiple colonizations of specialized clones
Authors: PECCOUD J. , FIGUEROA C. C. , SILVA A. X. , RAMIREZ C. C. , MIEUZET L. , BONHOMME J. , STOECKEL S. , PLANTEGENEST M. , SIMON J.‐C.
Published: November 2008

Asexuality confers demographic advantages to invasive taxa, but generally limits adaptive potential for colonizing of new habitats. Therefore, pre‐existing adaptations and habitat tolerance are essential in the success of asexual invaders. We investigated these key factors of invasiveness by assessing reproductive modes and host‐plant adaptations in the pea aphid, Acyrthosiphon pisum, a pest recently introduced into Chile. The pea aphid encompasses lineages differing in their reproductive mode, ranging from obligatory cyclical parthenogenesis to fully asexual reproduction. This species also shows variation in host use, with distinct biotypes specialized on different species of legumes as well as more polyphagous populations. In central Chile, microsatellite genotyping of pea aphids sampled on five crops and wild legumes revealed three main clonal genotypes, which showed striking associations with particular host plants rather than sampling locations. Phenotypic analyses confirmed their strong host specialization and demonstrated parthenogenesis as their sole reproductive mode. The genetic relatedness of these clonal genotypes with corresponding host‐specialized populations from the Old World indicated that each clone descended from a particular Eurasian biotype, which involved at least three successful introduction events followed by spread on different crops. This study illustrates that multiple introductions of highly specialized clones, rather than local evolution in resource use and/or selection of generalist genotypes, can explain the demographic success of a strictly asexual invader.
Fine‐scale genetic structure of a long‐lived reptile reflects recent habitat modification
Authors: MOORE J. A. , MILLER H. C. , DAUGHERTY C. H. , NELSON N. J.
Published: November 2008

Anthropogenic habitat fragmentation — ubiquitous in modern ecosystems — has strong impacts on gene flow and genetic population structure. Reptiles may be particularly susceptible to the effects of fragmentation because of their extreme sensitivity to environmental conditions and limited dispersal. We investigate fine‐scale spatial genetic structure, individual relatedness, and sex‐biased dispersal in a large population of a long‐lived reptile (tuatara, Sphenodon punctatus) on a recently fragmented island. We genotyped individuals from remnant forest, regenerating forest, and grassland pasture sites at seven microsatellite loci and found significant genetic structuring (RST = 0.012) across small distances (< 500 m). Isolation by distance was not evident, but rather, genetic distance was weakly correlated with habitat similarity. Only individuals in forest fragments were correctly assignable to their site of origin, and individual pairwise relatedness in one fragment was significantly higher than expected. We did not detect sex‐biased dispersal, but natural dispersal patterns may be confounded by fragmentation. Assignment tests showed that reforestation appears to have provided refuges for tuatara from disturbed areas. Our results suggest that fine‐scale genetic structuring is driven by recent habitat modification and compounded by the sedentary lifestyle of these long‐lived reptiles. Extreme longevity, large population size, simple social structure and random dispersal are not strong enough to counteract the genetic structure caused by a sedentary lifestyle. We suspect that fine‐scale spatial genetic structuring could occur in any sedentary species with limited dispersal, making them more susceptible to the effects of fragmentation.
Landscape genetic structure of coastal tailed frogs (Ascaphus truei) in protected vs. managed forests
Authors: SPEAR STEPHEN F. , STORFER ANDREW
Published: November 2008

Habitat loss and fragmentation are the leading causes of species’ declines and extinctions. A key component of studying population response to habitat alteration is to understand how fragmentation affects population connectivity in disturbed landscapes. We used landscape genetic analyses to determine how habitat fragmentation due to timber harvest affects genetic population connectivity of the coastal tailed frog (Ascaphus truei), a forest‐dwelling, stream‐breeding amphibian. We compared rates of gene flow across old‐growth (Olympic National Park) and logged landscapes (Olympic National Forest) and used spatial autoregression to estimate the effect of landscape variables on genetic structure. We detected higher overall genetic connectivity across the managed forest, although this was likely a historical signature of continuous forest before timber harvest began. Gene flow also occurred terrestrially, as connectivity was high across unconnected river basins. Autoregressive models demonstrated that closed forest and low solar radiation were correlated with increased gene flow. In addition, there was evidence for a temporal lag in the correlation of decreased gene flow with harvest, suggesting that the full genetic impact may not appear for several generations. Furthermore, we detected genetic evidence of population bottlenecks across the Olympic National Forest, including at sites that were within old‐growth forest but surrounded by harvested patches. Collectively, this research suggests that absence of forest (whether due to natural or anthropogenic changes) is a key restrictor of genetic connectivity and that intact forested patches in the surrounding environment are necessary for continued gene flow and population connectivity.
Genetic evidence of intercontinental movement of avian influenza in a migratory bird: the northern pintail (Anas acuta)
Authors: KOEHLER ANSON V. , PEARCE JOHN M. , FLINT PAUL L. , FRANSON J. CHRISTIAN , IP HON S.
Published: November 2008

The role of migratory birds in the movement of the highly pathogenic (HP) avian influenza H5N1 remains a subject of debate. Testing hypotheses regarding intercontinental movement of low pathogenic avian influenza (LPAI) viruses will help evaluate the potential that wild birds could carry Asian‐origin strains of HP avian influenza to North America during migration. Previous North American assessments of LPAI genetic variation have found few Asian reassortment events. Here, we present results from whole‐genome analyses of LPAI isolates collected in Alaska from the northern pintail (Anas acuta), a species that migrates between North America and Asia. Phylogenetic analyses confirmed the genetic divergence between Asian and North American strains of LPAI, but also suggested inter‐continental virus exchange and at a higher frequency than previously documented. In 38 isolates from Alaska, nearly half (44.7%) had at least one gene segment more closely related to Asian than to North American strains of LPAI. Additionally, sequences of several Asian LPAI isolates from GenBank clustered more closely with North American northern pintail isolates than with other Asian origin viruses. Our data support the role of wild birds in the intercontinental transfer of influenza viruses, and reveal a higher degree of transfer in Alaska than elsewhere in North America.
Comparative genomics and the study of evolution by natural selection
Authors: ELLEGREN HANS
Published: November 2008

Genomics profoundly affects most areas of biology, including ecology and evolutionary biology. By examining genome sequences from multiple species, comparative genomics offers new insight into genome evolution and the way natural selection moulds DNA sequence evolution. Functional divergence, as manifested in the accumulation of nonsynonymous substitutions in protein‐coding genes, differs among lineages in a manner seemingly related to population size. For example, the ratio of nonsynonymous to synonymous substitution (dN/dS) is higher in apes than in rodents, compatible with Ohta's nearly neutral theory of molecular evolution, which suggests that the fixation of slightly deleterious mutations contributes to protein evolution at an extent negatively correlated with effective population size. While this supports the idea that functional evolution is not necessarily adaptive, comparative genomics is uncovering a role for positive Darwinian selection in 10–40% of all genes in different lineages, estimates that are likely to increase when the addition of more genomes gives increased power. Again, population size seems to matter also in this context, with a higher proportion of fixed amino acid changes representing advantageous mutations in large populations. Genes that are particularly prone to be driven by positive selection include those involved with reproduction, immune response, sensory perception and apoptosis. Genetic innovations are also frequently obtained by the gain or loss of complete gene sequences. Moreover, it is increasingly realized, from comparative genomics, that purifying selection conserves much more than just the protein‐coding part of the genome, and this points at an important role for regulatory elements in trait evolution. Finally, genome sequencing using outbred or multiple individuals has provided a wealth of polymorphism data that gives information on population history, demography and marker evolution.
Conditional neutrality at two adjacent NBS‐LRR disease resistance loci in natural populations of Arabidopsis lyrata
Authors: GOS GESSECA , WRIGHT STEPHEN I
Published: November 2008

We examined patterns of nucleotide diversity at a genomic region containing two linked candidate disease resistance (NBS‐LRR) genes in seven populations of the outcrossing plant Arabidopsis lyrata. In comparison with two adjacent control genes and neutral reference genes across the genome, the NBS‐LRR genes exhibited elevated nonsynonymous variation and a large number of major‐effect polymorphisms causing early stop codons and/or frameshift mutations. In contrast, analysis of synonymous diversity provided no evidence that the region was subject to long‐term balancing selection or recent selective sweeps in any of the seven populations surveyed. Also in contrast with earlier surveys of one of these R genes, there was no evidence that the resistance genes or the major‐effect mutations were subject to elevated differentiation between populations. We suggest that conditional neutrality in the absence of the corresponding pathogen, rather than long‐term balancing selection or local adaptation, may in some circumstances be a significant cause of elevated functional polymorphism at R genes. In contrast with the R genes, analysis of diversity and differentiation at the flanking FERONIA locus showed high population divergence, suggesting local adaptation on this locus controlling male–female signalling during fertilization.
The interaction of sexually and naturally selected traits in the adaptive radiations of cichlid fishes
Authors: SALZBURGER WALTER
Published: November 2008

The question of how genetic variation translates into organismal diversity has puzzled biologists for decades. Despite recent advances in evolutionary and developmental genetics, the mechanisms that underlie adaptation, diversification and evolutionary innovation remain largely unknown. The exceptionally diverse species flocks of cichlid fishes are textbook examples of adaptive radiation and explosive speciation and emerge as powerful model systems to study the genetic basis of animal diversification. East Africa's hundreds of endemic cichlid species are akin to a natural mutagenesis screen and differ greatly not only in ecologically relevant (hence naturally selected) characters such as mouth morphology and body shape, but also in sexually selected traits such as coloration. One of the most fascinating aspects of cichlid evolution is the frequent occurrence of evolutionary parallelisms, which has led to the question whether selection alone is sufficient to produce these parallel morphologies, or whether a developmental or genetic bias has influenced the direction of diversification. Here, I review fitness‐relevant traits that could be responsible for the cichlids’ evolutionary success and assess whether these were shaped by sexual or natural selection. I then focus on the interaction and the relative importance of sexual vs. natural selection in cichlid evolution. Finally, I discuss what is currently known about the genes underlying the morphogenesis of adaptively relevant traits and highlight the importance of the forthcoming cichlid genomes in the quest of the genetic basis of diversification in this group.
A new oxidative sensing and regulation pathway mediated by the MgrA homologue SarZ in Staphylococcus aureus
Authors: Chen Peng R. , Nishida Satoshi , Poor Catherine B. , Cheng Alice , Bae Taeok , Kuechenmeister Lisa , Dunman Paul M. , Missiakas Dominique , He Chuan
Published: November 2008

Oxidative stress serves as an important host/environmental signal that triggers a wide range of responses from the human pathogen Staphylococcus aureus. Among these, a thiol‐based oxidation sensing pathway through a global regulator MgrA controls the virulence and antibiotic resistance of the bacterium. Herein, we report a new thiol‐based oxidation sensing and regulation system that is mediated through a parallel global regulator SarZ. SarZ is a functional homologue of MgrA and is shown to affect the expression of ∼87 genes in S. aureus. It uses a key Cys residue, Cys‐13, to sense oxidative stress and to co‐ordinate the expression of genes involved in metabolic switching, antibiotic resistance, peroxide stress defence, virulence, and cell wall properties. The discovery of this SarZ‐mediated regulation, mostly independent from the MgrA‐based regulation, fills a missing gap of oxidation sensing and response in S. aureus.
Functional analysis of NsrR, a nitric oxide‐sensing Rrf2 repressor in Neisseria gonorrhoeae
Authors: Isabella Vincent M. , Lapek Jr John D. , Kennedy Edward M. , Clark Virginia L.
Published: November 2008

Nitric oxide (NO) has been shown to be an important component of the human immune response, and as such, it is important to understand how pathogenic organisms respond to its presence. In Neisseria gonorrhoeae, recent work has revealed that NsrR, an Rrf2‐type transcriptional repressor, can sense NO and control the expression of genes responsible for NO metabolism. A highly pure extract of epitope‐tagged NsrR was isolated and mass spectroscopic analysis suggested that the protein contained a [2Fe−2S] cluster. NsrR/DNA interactions were thoroughly analysed in vitro. Using EMSA analysis, NsrR::FLAG was shown to interact with predicted operators in the norB, aniA and nsrR upstream regions with a Kd of 7, 19 and 35 nM respectively. DNase I footprint analysis was performed on the upstream regions of norB and nsrR, where NsrR was shown to protect the predicted 29 bp binding sites. The presence of exogenously added NO inhibited DNA binding by NsrR. Alanine substitution of C90, C97 or C103 in NsrR abrogated repression of norB::lacZ and inhibited DNA binding, consistent with their presumed role in co‐ordination of a NO‐sensitive Fe–S centre required for DNA binding.
Synchronous replication initiation in novel Mycobacterium tuberculosis dnaA cold‐sensitive mutants
Authors: Nair Naveen , Dziedzic Renata , Greendyke Rebecca , Muniruzzaman Syed , Rajagopalan Malini , Madiraju Murty V.
Published: November 2008

The genetic aspects of oriC replication initiation in Mycobacterium tuberculosis are largely unknown. A two‐step genetic screen was utilized for isolating M. tuberculosis dnaA cold‐sensitive (cos) mutants. First, a resident plasmid expressing functional dnaA integrated at the attB locus in dnaA null background was exchanged with an incoming plasmid bearing a mutagenized dnaA gene. Next, the mutants that were defective for growth at 30°C, a non‐permissive temperature, but resumed growth and DNA synthesis when shifted to 37°C, a permissive temperature, were subsequently selected. Nucleotide sequencing analysis located mutations to different regions of the dnaA gene. Modulation of the growth temperatures led to synchronized DNA synthesis. The dnaA expression under synchronized DNA replication conditions continued to increase during the replication period, but decreased thereafter reflecting autoregulation. The dnaAcos mutants at 30°C were elongated suggesting that they may possibly be blocked during the cell division. The DnaA115 protein is defective in its ability to interact with ATP at 30°C, but not at 37°C. Our results suggest that the optimal cell cycle progression and replication initiation in M. tuberculosis requires that the dnaA promoter remains active during the replication period and that the DnaA protein is able to interact with ATP.
Candida albicans cell surface superoxide dismutases degrade host‐derived reactive oxygen species to escape innate immune surveillance
Authors: Frohner Ingrid E. , Bourgeois Christelle , Yatsyk Kristina , Majer Olivia , Kuchler Karl
Published: November 2008

Mammalian innate immune cells produce reactive oxygen species (ROS) in the oxidative burst reaction to destroy invading microbial pathogens. Using quantitative real‐time ROS assays, we show here that both yeast and filamentous forms of the opportunistic human fungal pathogen Candida albicans trigger ROS production in primary innate immune cells such as macrophages and dendritic cells. Through a reverse genetic approach, we demonstrate that coculture of macrophages or myeloid dendritic cells with C. albicans cells lacking the superoxide dismutase (SOD) Sod5 leads to massive extracellular ROS accumulation in vitro. ROS accumulation was further increased in coculture with fungal cells devoid of both Sod4 and Sod5. Survival experiments show that C. albicans mutants lacking Sod5 and Sod4 exhibit a severe loss of viability in the presence of macrophages in vitro. The reduced viability of sod5Δ/Δ and sod4Δ/Δsod5Δ/Δ mutants relative to wild type is not evident with macrophages from gp91phox−/− mice defective in the oxidative burst activity, demonstrating a ROS‐dependent killing activity of macrophages targeting fungal pathogens. These data show a physiological role for cell surface SODs in detoxifying ROS, and suggest a mechanism whereby C. albicans, and perhaps many other microbial pathogens, can evade host immune surveillance in vivo.
Involvement of OsSPX1 in phosphate homeostasis in rice
Authors: Wang Chuang , Ying Shan , Huang Hongjie , Li Kuan , Wu Ping , Shou Huixia
Published: November 2008

Arabidopsis thaliana SPX (SYG/PHO81/XPR1) domain genes have recently been shown to be involved in the phosphate (Pi) signaling pathway. We show here that a rice (Oryza sativa) SPX gene, OsSPX1, is specifically induced by Pi starvation in roots. Suppression of OsSPX1 by RNA interference resulted in severe signs of toxicity caused by the over‐accumulation of Pi, similar to that found in OsPHR2 (phosphate starvation response transcription factor 2) overexpressors and pho2 (phosphate‐responsive mutant 2). Quantitative RT‐PCR showed that expression of OsSPX1 was strongly induced in OsPHR2 overexpression and pho2 mutant plants, indicating that OsSPX1 occurs downstream of OsPHR2 and PHO2. The expression of 10 genes associated with the phosphate‐starvation signal pathways was analyzed. Expression of OsPT2 (phosphate transporter 2) and OsPT8 was significantly induced in OsSPX1‐RNAi (OsSPX1‐Ri) plants, suggesting that over‐accumulation of Pi in OsSPX1‐Ri plants results from an increase in Pi transport. In contrast, overexpression of OsSPX1 suppressed the induction of expression by Pi starvation of all 10 phosphate starvation‐induced genes tested: IPS1 (induced by phosphate starvation 1), IPS2, OsPAP10 (purple acid phosphatase 10), OsSQD2 (sulfoquinovosyldiacylglycerol 2), miR399d and miR399j (microRNA 399), OsPT2, OsPT3, OsPT6 and OsPT8. This suggests that OsSPX1 acts via a negative feedback loop to optimize growth under phosphate‐limited conditions.
Both the conserved GRAS domain and nuclear localization are required for SHORT‐ROOT movement
Authors: Gallagher Kimberly L. , Benfey Philip N.
Published: November 2008

Transcription factor movement is well established in plants. Since the initial report of KNOTTED movement, more than a dozen transcription factors have been shown to move in plants. However, the developmental significance of movement is not known. Using the SHORT‐ROOT (SHR) transcription factor as a tool for studying cell‐to‐cell trafficking, we show that movement of SHR from its site of synthesis is necessary for normal development of the Arabidopsis root. We identify multiple regions of SHR that are required for intra‐ and intercellular movement of SHR, including a region that is necessary for movement but not activity. We made the surprising discovery that the capacity for intercellular movement may be conserved among other GRAS family proteins. Finally, we provide evidence that movement requires both cytoplasmic and nuclear localization, strongly suggesting a mechanistic link between nuclear transport and cell‐to‐cell movement.
RKP, a RING finger E3 ligase induced by BSCTV C4 protein, affects geminivirus infection by regulation of the plant cell cycle
Authors: Lai Jianbin , Chen Hao , Teng Kunling , Zhao Qingzhen , Zhang Zhonghui , Li Yin , Liang Liming , Xia Ran , Wu Yaorong , Guo Huishan , Xie Qi
Published: November 2008

The C4 protein fromCurtovirusis known as a major symptom determinant, but the mode of action of the C4 protein remains unclear. To understand the mechanism of involvement of C4 protein in virus–plant interactions, we introduced theC4gene fromBeet severe curly top virus(BSCTV) into Arabidopsis under a conditional expression promoter; the resulting overexpression ofBSCTV C4led to abnormal host cell division. RKP, a RING finger protein, which is a homolog of the human cell cycle regulator KPC1, was discovered to be induced by BSCTV C4 protein. Mutation ofRKPreduced the susceptibility to BSCTV in Arabidopsis and impaired BSCTV replication in plant cells. Callus formation is impaired inrkpmutants, indicating a role of RKP in the plant cell cycle. RKP was demonstrated to be a functional ubiquitin E3 ligase and is able to interact with cell‐cycle inhibitor ICK/KRP proteinsin vitro. Accumulation of the protein ICK2/KRP2 was found increased in therkpmutant. The above results strengthen the possibility that RKP might regulate the degradation of ICK/KRP proteins. In addition, the protein level of ICK2/KRP2 was decreased upon BSCTV infection. Overexpression ofICK1/KRP1in Arabidopsis could reduce the susceptibility to BSCTV. In conclusion, we found thatRKPis induced by BSCTV C4 and may affect BSCTV infection by regulating the host cell cycle.
MERISTEM‐DEFECTIVE, an RS domain protein, is required for the correct meristem patterning and function in Arabidopsis
Authors: Casson Stuart A. , Topping Jennifer F. , Lindsey Keith
Published: November 2008

Plant growth and development is dependent on the specification and maintenance of pools of stem cells found in the meristems. Mutations in the Arabidopsis MERISTEM‐DEFECTIVE (MDF) gene lead to a loss of stem cell and meristematic activity in the root and vegetative shoot. MDF encodes a putative RS domain protein with a predicted role in transcription or RNA processing control. mdf mutants exhibit decreased levels of PINFORMED2 (PIN2) and PIN4 mRNAs, which is associated with a reduction in PIN:GFP levels, and with a defective auxin maximum in the basal region of the developing mdf embryo and seedling root meristem. Seedling roots also exhibit reduced PLETHORA (PLT), SCARECROW and SHORTROOT gene expression, a loss of stem cell activity, terminal differentiation of the root meristem and defective cell patterning. MDF expression is not defective in the bodenlos, pin1 or eir1/pin2 auxin mutants, and is not modulated by exogenous auxin. plt1 plt2 double mutants have unaffected levels of MDF RNA, indicating that MDF acts upstream of PIN and PLT gene expression. Differentiation of the shoot stem cell pool also occurs in mdf mutants, associated with a reduced WUSCHEL (WUS) expression domain and expanded CLAVATA3 (CLV3) domain. Overexpression of MDF leads to the activation of markers of embryonic identity and ectopic meristem activity in vegetative tissues. These results demonstrate a requirement for the MDF‐dependent pathway in regulating PIN/PLT‐ and WUS/CLV‐mediated meristem activity.
EZ‐Rhizo: integrated software for the fast and accurate measurement of root system architecture
Authors: Armengaud Patrick , Zambaux Kevin , Hills Adrian , Sulpice Ronan , Pattison Richard J. , Blatt Michael R. , Amtmann Anna
Published: November 2008

The root system is essential for the growth and development of plants. In addition to anchoring the plant in the ground, it is the site of uptake of water and minerals from the soil. Plant root systems show an astonishing plasticity in their architecture, which allows for optimal exploitation of diverse soil structures and conditions. The signalling pathways that enable plants to sense and respond to changes in soil conditions, in particular nutrient supply, are a topic of intensive research, and root system architecture (RSA) is an important and obvious phenotypic output. At present, the quantitative description of RSA is labour intensive and time consuming, even using the currently available software, and the lack of a fast RSA measuring tool hampers forward and quantitative genetics studies. Here, we describe EZ‐Rhizo: a Windows‐integrated and semi‐automated computer program designed to detect and quantify multiple RSA parameters from plants growing on a solid support medium. The method is non‐invasive, enabling the user to follow RSA development over time. We have successfully applied EZ‐Rhizo to evaluate natural variation in RSA across 23 Arabidopsis thaliana accessions, and have identified new RSA determinants as a basis for future quantitative trait locus (QTL) analysis.
Dynamic organization of COPII coat proteins at endoplasmic reticulum export sites in plant cells
Authors: Hanton Sally L. , Matheson Loren A. , Chatre Laurent , Brandizzi Federica
Published: November 2008

Protein export from the endoplasmic reticulum (ER) is mediated by the accumulation of COPII proteins such as Sar1, Sec23/24 and Sec13/31 at specialized ER export sites (ERES). Although the distribution of COPII components in mammalian and yeast systems is established, a unified model of ERES dynamics has yet to be presented in plants. To investigate this, we have followed the dynamics of fluorescent fusions to inner and outer components of the coat, AtSec24 and AtSec13, in three different plant model systems: tobacco and Arabidopsis leaf epidermis, as well as tobacco BY‐2 suspension cells. In leaves, AtSec24 accumulated at Golgi‐associated ERES, whereas AtSec13 showed higher levels of cytosolic staining compared with AtSec24. However, in BY‐2 cells, both AtSec13 and AtSec24 labelled Golgi‐associated ERES, along with AtSec24. To correlate the distribution of the COPII coat with the dynamics of organelle movement, quantitative live‐cell imaging analyses demonstrated that AtSec24 and AtSec13 maintained a constant association with Golgi‐associated ERES, irrespective of their velocity. However, recruitment of AtSec24 and AtSec13 to ERES, as well as the number of ERES marked by these proteins, was influenced by export of membrane cargo proteins from the ER to the Golgi. Additionally, the increased availability of AtSec24 affected the distribution of AtSec13, inducing recruitment of this outer COPII coat component to ERES. These results provide a model that, in plants, protein export from the ER occurs via sequential recruitment of inner and outer COPII components to form transport intermediates at mobile, Golgi‐associated ERES.
Arabidopsis mitogen‐activated protein kinase MPK12 interacts with the MAPK phosphatase IBR5 and regulates auxin signaling
Authors: Lee Jin Suk , Wang Shucai , Sritubtim Somrudee , Chen Jin‐Gui , Ellis Brian E.
Published: November 2008

Mitogen‐activated protein kinase (MAPK) phosphatases are important negative regulators in the MAPK signaling pathways responsible for many essential processes in plants, including development, stress management and hormonal responses. A mutation in INDOLE‐3‐BUTYRIC ACID‐RESPONSE5 (IBR5), which is predicted to encode a dual‐specificity MAPK phosphatase, was previously reported to confer reduced sensitivity to auxin and ABA in Arabidopsis roots. To further characterize IBR5, and to understand how it might help integrate MAPK cascades with hormone signaling, we searched for IBR5‐interacting MAPKs. Yeast two‐hybrid assays, in vitro binding assays and in vivo protein co‐immunoprecipitation studies demonstrated that MPK12 and IBR5 are physically coupled. The C‐terminus of MPK12 appears to be essential for its interaction with IBR5, and in vitro dephosphorylation and immunocomplex kinase assays indicated that activated MPK12 is efficiently dephosphorylated and inactivated by IBR5. MPK12 and IBR5 mRNAs are both widely expressed across Arabidopsis tissues, and at the subcellular level each protein is predominantly localized in the nucleus. In transgenic plants with reduced expression of the MPK12 gene, root growth is hypersensitive to exogenous auxins, but shows normal ABA sensitivity. MPK12 suppression in an ibr5 background partially complements the ibr5 auxin‐insensitivity phenotype. Our results demonstrate that IBR5 is a bona fide MAPK phosphatase, and suggest that MPK12 is both a physiological substrate of IBR5 and a novel negative regulator of auxin signaling in Arabidopsis.
Extracellular transport and integration of plant secretory proteins into pathogen‐induced cell wall compartments
Authors: Meyer Dorit , Pajonk Simone , Micali Cristina , O’Connell Richard , Schulze‐Lefert Paul
Published: November 2008

Many fungal parasites enter plant cells by penetrating the host cell wall and, thereafter, differentiate specialized intracellular feeding structures, called haustoria, by invagination of the plant’s plasma membrane. Arabidopsis PEN gene products are known to act at the cell periphery and function in the execution of apoplastic immune responses to limit fungal entry. This response underneath fungal contact sites is tightly linked with the deposition of plant cell wall polymers, including PMR4/GSL5‐dependent callose, in the paramural space, thereby producing localized wall thickenings called papillae. We show that powdery mildew fungi specifically induce the extracellular transport and entrapment of the fusion protein GFP–PEN1 syntaxin and its interacting partner monomeric yellow fluorescent protein (mYFP)–SNAP33 within the papillary matrix. Remarkably, PMR4/GSL5 callose, GFP–PEN1, mYFP–SNAP33, and the ABC transporter GFP–PEN3 are selectively incorporated into extracellular encasements surrounding haustoria of the powdery mildew Golovinomyces orontii, suggesting that the same secretory defense responses become activated during the formation of papillae and haustorial encasements. This is consistent with a time‐course analysis of the encasement process, indicating that these extracellular structures are generated through the extension of papillae. We show that PMR4/GSL5 callose accumulation in papillae and haustorial encasements occurs independently of PEN1 syntaxin. We propose a model in which exosome biogenesis/release serves as a common transport mechanism by which the proteins PEN1 and PEN3, otherwise resident in the plasma membrane, together with membrane lipids, become stably incorporated into both pathogen‐induced cell wall compartments.
Nodular vasculitis in systemic lupus erythematosus
Authors: Westers‐Attema Annet , Van Tubergen A. , Plasschaert H. , Van Marion A. M. W. , Frank J. , Poblete‐Gutiérrez P.
Published: November 2008

A 42‐year‐old man presented with fever, photosensitivity, headaches, myalgia, hyperhidrosis, muscle weakness, alopecia, nasal crustae, weight loss, painful nails, arthritis, oral ulcers, erythema, discoid cutaneous lesions, and painful subcutaneous nodes. We made a diagnosis of systemic lupus erythematosus (SLE), type II cryoglobulinemia, and nodular vasculitis. In the skin, different types of vasculitis may be observed. Typically, histology shows leukocytoclastic vasculitis of superficial vessels both in SLE and mixed cryoglobulinemia, which clinically results in palpable purpura. In our patient, however, histopathological examination of the subcutaneous nodes not only revealed leukocytoclastic vasculitis of the superficial vasculature but also showed even more extensive involvement of dermal and subdermal small and medium sized vessels, giving rise to a nodular vasculitis.
Penile pyoderma gangrenosum: successful treatment with colchicine
Authors: Parren Lizelotte J. M. T. , Nellen Ruud G. L. , Van Marion Arienne M. W. , Henquet Charles J. M. , Frank Jorge , Poblete‐Gutiérrez Pamela
Published: November 2008

Pyoderma gangrenosum is an ulcerative skin disease with variable clinical outcomes. The diagnosis is based on clinical features and exclusion of other ulcerative diseases. To date, a specific treatment is not known. Since the disease can be destructive, aggressive treatment is preferable. Here, we present a patient with a penile pyoderma gangrenosum who was successfully treated with low‐dose colchicine.
Neonatal Langerhans’ cell histiocytosis: a rare and potentially life‐threatening disease
Authors: Mosterd Klara , Van Marion Arienne , Van Steensel Maurice A. M.
Published: November 2008

Abastract

A 5‐day‐old girl presented with thrombocytopenia, leukopenia, anemia and crusted purpura on the skin. The diagnosis Langerhans’ cell histiocytosis (LCH) was suspected on clinical grounds and subsequently confirmed by histopathological examination of a skin biopsy. Cytological examination of a bone marrow aspirate revealed numerous histiocytes, which is suspect for bone‐marrow infiltration by LCH.

LCH is a condition in which a clonal population of Langerhans’ cells accumulates in various tissues, causing tissue damage and/or dysfunction. The prognosis of this disease depends on the age of the patient, the extent of the disease and the presence of vital organ failure. In case of organ dysfunction, systemic chemotherapy is indicated.

Although very rare, LCH can be a life‐threatening disease. Early diagnosis can improve chances of survival. We briefly discuss diagnostic procedures and treatment.
Basal cell carcinoma and trichoepithelioma: a possible matter of confusion
Authors: Arits Aimée H. M. M. , Parren Lizelotte J. M. T. , Van Marion Arienne M. W. , Sommer Anja , Frank Jorge , Kelleners‐Smeets Nicole W. J.
Published: November 2008

Difficulty in differentiation between a solitary basal cell carcinoma, which is known as a malign skin lesion and a benign trichoepithelioma, is a frequent problem in all day dermatologic practice. Clinically as well as histopathologically there are a lot of resemblances between these skin tumors. By means of two real life cases, we give here an overview of the possible problems and appliances in distinguishing these two entities; at the end we do some recommendation about the policy.
Coincidence of cutaneous follicle center lymphoma and diffuse large B‐cell lymphoma
Authors: Van Tuyll van Serooskerken Anne‐Moon , Mosterd Klara , Veraart Joep C. , Vermeer Maarten H. , Frank Jorge , Van Marion Ariënne M. W.
Published: November 2008

Primary cutaneous follicle center lymphoma (PCFCL) is a neoplasm with differentiation of centrocytes and centroblasts presenting in the skin. At the time of initial manifestation, extracutaneous involvement is absent. PCFCL is considered as an indolent variant of primary cutaneous B‐cell lymphomas since dissemination to extracutaneous sites is rare and the prognosis is favorable. Here we describe a 30‐year‐old man who was diagnosed with a cutaneous FCL and did not show extracutaneous affection at the time of occurrence. Six months later, however, he developed a diffuse large B‐cell non‐Hodgkin lymphoma localized in several lymph nodes of the neck that most likely reflects the occurrence of a second primary tumor in the same patient.
Photoallergic contact dermatitis caused by ultraviolet filters in different sunscreens
Authors: Collaris Esther J. H. , Frank Jorge
Published: November 2008

Over the last decade, a change in the public awareness regarding the possible danger of excessive sunlight exposure has resulted in an increased consumption of sunscreens. These products contain a broad spectrum of putative sensitizers that can cause contact dermatitis and, upon exposure to ultraviolet (UV) irradiation, photocontact dermatitis. Among these sensitizing compounds, UV filters are the most frequent cause of photoallergic reactions. Although rarely observed, we here describe the occurrence of a photoallergic contact dermatitis in a 55‐year‐old man after the use of two different sunscreens. Photopatch testing showed hypersensitivity reactions of the delayed type against three different chemical UV filters, 4‐tert‐butyl‐4‐ methoxy‐dibenzoylmethane (Parsol 1789), 2‐ethylhexyl‐p‐methoxycinnamate (Parsol MCX), and isoamyl‐p‐methoxycinnamate (Neoheliopan).
Skin abnormalities in individuals with macrocephaly: Cowden disease from a dermatologist's point of view
Authors: Van Der Velden Jaap J. A. J. , Vreeburg Maaike , Smeets Eric E. J. , Schrander‐Stumpel Constance T. R. M. , Van Steensel Maurice A. M.
Published: November 2008

Cowden disease is a rare autosomal dominant disorder characterized by multiple hamartomas and (malignant) tumors affecting major organs including the breast, thyroid, endometrium, brain, skin and mucosa. Diagnostic criteria as formulated by the International Cowden Consortium serve as a guideline to clinically identify patients in which Cowden disease is suspected.

However, the spectrum of abnormalities associated with PTEN mutations is very broad, such that the term PTEN hamartoma tumor syndrome (PTHS) is often used. The diagnostic criteria for Cowden disease do not always serve to reliably identify patients who fall within the PTHS spectrum. Therefore, it is important that clinicians are aware of features that should raise the suspicion of such a syndrome.

To illustrate this point, we present three patients with clinical features of the PTEN hamartoma tumor syndrome spectrum. These patients have macrocephaly in common. Two of them meet the criteria for Cowden disease; one patient refused mutation analysis, while mutation analysis in the other patient revealed no PTEN mutation. The third patient does not meet the criteria for Cowden disease; however, genetic analysis showed a pathogenic mutation in the PTEN gene.

Dermatologists regularly encounter the (muco‐)cutaneous abnormalities that can be seen in PTEN hamartoma tumor syndrome. These findings combined with a (family) history of internal malignancy or a macrocephaly should raise the suspicion of PTHS, even in the absence of classical Cowden criteria.
Tophi as first clinical sign of gout
Authors: Thissen Carleine A. C. B. , Frank Jorge , Lucker Georges P. H.
Published: November 2008

Gout results from deposition of monosodium urate crystals in different body tissues, including the skin and soft tissues. With increasing prosperity a rising prevalence of the disease can be observed, especially in highly industrialized countries. Gout can present with acute and painful attacks of arthritis that can affect several joints. In addition, nodular masses of uric acid crystals can develop, which are referred to as tophi. Although tophaceous gout usually is a sign of long during and chronic disease tophi can also occur as first symptom of the disorder. Here, we report on an 85‐year‐old woman who was diagnosed with tophaceous gout devoid of a prior medical history of the disease.
Lymphedema–distichiasis syndrome: a distinct type of primary lymphedema caused by mutations in the FOXC2 gene
Authors: Vreeburg Maaike , Heitink Martijn V. , Damstra Robert J. , Moog Ute , Van Geel Michel , Van Steensel Maurice A. M.
Published: November 2008

Lymphedema–distichiasis syndrome (LD, OMIM 153400) is an autosomal dominant disorder with variable expression. It is caused by mutations in the FOXC2‐gene, which codes for a forkhead transcription factor involved in the development of the lymphatic and vascular system. LD is characterized by late childhood or pubertal onset lymphedema of the limbs and distichiasis (double row of eyelashes). While the latter is the most common expression of LD, venous insufficiency occurs in half of the patients. Other associations have been reported, including congenital heart disease, ptosis, cleft lip/palate and spinal extradural cysts.

Here we describe a family with classical lymphedema–distichiasis syndrome caused by a duplication in the FOXC2‐gene.
Cryptococcal infection presenting as cellulitis in a renal transplant recipient
Authors: Orsini J. , Nowakowski J. , Delaney V. , Sakoulas G. , Wormser G.P.
Published: November 2008

Abstract: Opportunistic infections of skin and soft tissue represent a rare but serious complication following solid organ transplantation. We report a case of severe soft tissue infection caused by Cryptococcus neoformans in a renal transplant recipient. Physicians need to consider the possibility of opportunistic pathogens when managing infections in immunocompromised hosts, especially when symptoms persist despite seemingly appropriate empiric antimicrobial therapy. Tissue sampling for histological and microbiological evaluation is usually necessary to establish a diagnosis.
Unusual presentation of Ramsay Hunt syndrome in renal transplant patients: case report and literature review
Authors: Mortada R.A. , El Fakih R.O. , Assi M.
Published: November 2008

Abstract: Ramsay Hunt syndrome (RHS) is a rare manifestation of varicella zoster virus (VZV) infection that accounts for around 12% of all cases of facial paralysis. Although it is more common in immunosuppressed individuals, it has not been yet reported in kidney transplant recipients. We describe the case of a 41‐year‐old man with a history of renal transplant for whom the diagnosis and treatment of RHS were delayed owing to an unusual presentation. We also review the literature on VZV infection in renal transplant patients.
Disseminated tuberculosis following second unrelated cord blood transplantation for acute myelogenous leukemia
Authors: Shima T. , Yoshimoto G. , Miyamoto T. , Yoshida S. , Kamezaki K. , Takenaka K. , Iwasaki H. , Harada N. , Nagafuji K. , Teshima T. , Shimono N. , Akashi K.
Published: November 2008

Abstract: Here we report the case of a 43‐year‐old Japanese woman with acute myelogenous leukemia who underwent 2 unrelated cord blood transplantations (UCBT), terminating in fatal disseminated tuberculosis (TB). The patient did not achieve remission despite intensive chemotherapy, and subsequently underwent UCBT with a standard conditioning regimen. However, engraftment was not achieved. Fifty days after the first UCBT, the patient underwent a second UCBT with a reduced‐intensity conditioning regimen. She developed a pre‐engraftment immune reaction, which responded well to prednisolone, and engraftment was documented. However, 50 days after the second UCBT, the patient presented with high fever and developed pneumonia despite antibiotic and antifungal treatments. Thereafter, Mycobacterium tuberculosis was detected in blood cultures and specimens of bronchoalveolar lavage, thus indicating disseminated TB. Despite anti‐tuberculous treatment, she died on day 85. TB should always be considered as a possible diagnosis when treating febrile immunocompromised patients.
Hydroid assemblages from the Southwestern Atlantic Ocean (34–42° S)
Authors: Genzano Gabriel N. , Giberto Diego , Schejter Laura , Bremec Claudia , Meretta Pablo
Published: November 2008

This paper provides updated taxonomic knowledge about hydrozoan species and provides ecological information including geographical and bathymetric distributions and biological substrata for the various hydroid assemblages from the Sub‐Antarctic Biogeographical Region, mainly Buenos Aires and the Uruguayan coasts. Five of the 41 species found are new records for the study region. Thirty‐one species (75.6%), all found at depths of less than 80 m, have cosmopolitan distributions. Biodiversity decreased markedly below 80 m depth, where nine species (≈22%) distributed in the Southern hemisphere and one endemic species (2.4%) were found. Most species were non‐specific epizoites, occurring on diverse substrata. A non‐parametric multivariate similarity analysis revealed nine species groups that were correlated with large‐scale and local oceanographic patterns and with the availability of suitable substrata. The main hydroid substrata for eight of the groups were cnidarians, molluscs (mainly blue mussels), quartzite rocks and sponges. In a single group found in Patagonian scallop beds, the main biological substrata were polychaete tubes, other hydroids and scallops.
Diel vertical migration of medusae in the open Southern Adriatic Sea over a short time period (July 2003)
Authors: Lučić Davor , Benović Adam , Morović Mira , Batistić Mirna , Onofri Ivona
Published: November 2008

Diel vertical migration (DVM) of medusae was investigated at a fixed station in the oligotrophic Southern Adriatic Sea at several depths during summer (July) 2003. We hypothesized that medusan DVM is considerably influenced by environmental variables such as hydrographic features, light intensities, and potential prey densities. We used short‐term repetitive sampling as an approach to detail these relationships. Of the 26 species collected, the highest abundance was in the layer between the thermocline (15 m) and 100 m depth, where Rhopalonema velatum predominated, reaching the maximum count of 93 individuals per 10 m3. Seven species were observed over a wide depth range: Solmissus albescens (15–1200 m), R. velatum (0–800 m), Persa incolorata (50–1200 m), Octophialucium funerarium (200–1200 m), Arctapodema australis (200–1200 m), Amphinema rubra (100–800 m), and Rhabdoon singulare (15–600). According to the medusan weighted mean depth (WMD) calculations, the longest DVMs were noted for the deep‐sea species S. albescens, O. funerarium, and A. australis. The shallowest species, Aglaura hemistoma, was primarily non‐migratory. Certain medusan assemblages were associated consistently with a particular depth layer characterized by a particular light intensity. The interplay of environmental factors and trophic relationships explains some of the features of medusan migratory patterns. These findings thus contribute to understanding the variables that determine patterns of medusan vertical migratory behavior.