bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mitochondrial DNA reveals multiple Northern Hemisphere introductions of Caprella mutica (Crustacea, Amphipoda)
Authors: ASHTON GAIL V. , STEVENS MARK I. , HART MARK C. , GREEN DAVID H. , BURROWS MICHAEL T. , COOK ELIZABETH J. , WILLIS KATE J. 
Published: February 2008

Abstract Caprella mutica (Crustacea, Amphipoda) has been widely introduced to non‐native regions in the last 40 years. Its native habitat is sub‐boreal northeast Asia, but in the Northern Hemisphere, it is now found on both coasts of North America, and North Atlantic coastlines of Europe. Direct sequencing of mitochondrial DNA (cytochrome c oxidase subunit I gene) was used to compare genetic variation in native and non‐native populations of C. mutica. These data were used to investigate the invasion history of C. mutica and to test potential source populations in Japan. High diversity (31 haplotypes from 49 individuals), but no phylogeographical structure, was identified in four populations in the putative native range. In contrast, non‐native populations showed reduced genetic diversity (7 haplotypes from 249 individuals) and informative phylogeographical structure. Grouping of C. mutica populations into native, east Pacific, and Atlantic groups explained the most among‐region variation (59%). This indicates independent introduction pathways for C. mutica to the Pacific and Atlantic coasts of North America. Two dominant haplotypes were identified in eastern and western Atlantic coastal populations, indicating several dispersal routes within the Atlantic. The analysis indicated that several introductions from multiple sources were likely to be responsible for the observed global distribution of C. mutica, but the pathways were least well defined among the Atlantic populations. The four sampled populations of C. mutica in Japan could not be identified as the direct source of the non‐native populations examined in this study. The high diversity within the Japan populations indicates that the native range needs to be assessed at a far greater scale, both within and among populations, to accurately assess the source of the global spread of C. mutica.
Interspecific hybridization and restricted trans‐Pacific gene flow in the Tropical Eastern Pacific Pocillopora
Authors: COMBOSCH DAVID J. , GUZMAN HECTOR M. , SCHUHMACHER HELMUT , VOLLMER STEVEN V. 
Published: February 2008

AbstractCoral reefs in the Tropical Eastern Pacific (TEP) are among the most isolated in the world. This isolation has resulted in relatively low species diversity but comparatively high endemism. The dominant reef‐building corals of the TEP are the Pocillopora corals, a ubiquitous Indo‐Pacific genus commonly regarded as inferior reef‐builder. In addition to being the dominant reef‐builders in the TEP, the Pocilloporids have undergone a reproductive shift from internally brooding larvae through most of their Indo‐Pacific range to free‐spawning in the TEP. Using genetic data from the internally transcribed spacer (ITS) regions of the nuclear ribosomal DNA gene cluster, we show here that this apparent reproductive shift coincides with interspecific hybridization among TEP Pocillopora species. We document a pattern of one‐way gene flow into the main TEP reef builder P. damicornis from one or both of its TEP congeners —P. eydouxi and P. elegans. Our data provide preliminary evidence that trans‐Pacific gene flow in P. damicornis between the Central and Eastern Pacific is restricted as well (ΦST = 0.419, P < 0.0001). In combination, these results suggest that Eastern Pacific corals exist in relative isolation from their Central Pacific counterparts and interact with each other differently via hybridization.
Can we stop transgenes from taking a walk on the wild side?
Authors: DLUGOSCH KATRINA M. , WHITTON JEANNETTE 
Published: February 2008

AbstractWhether the potential costs associated with broad‐scale use of genetically modified organisms (GMOs) outweigh possible benefits is highly contentious, including within the scientific community. Even among those generally in favour of commercialization of GM crops, there is nonetheless broad recognition that transgene escape into the wild should be minimized. But is it possible to achieve containment of engineered genetic elements in the context of large scale agricultural production? In a previous study, Warwick et al. (2003) documented transgene escape via gene flow from herbicide resistant (HR) canola (Brassica napus) into neighbouring weedy B. rapa populations (Fig. 1) in two agricultural fields in Quebec, Canada. In a follow‐up study in this issue of Molecular Ecology, Warwick et al. (2008) show that the transgene has persisted and spread within the weedy population in the absence of selection for herbicide resistance. Certainly a trait like herbicide resistance is expected to spread when selected through the use of the herbicide, despite potentially negative epistatic effects on fitness. However, Warwick et al.'s findings suggest that direct selection favouring the transgene is not required for its persistence. So is there any hope of preventing transgene escape into the wild?Weedy Brassica rapa (orange flags) growing in a B. napus field. (Photo: MJ Simard)image
MicroRNA399 is a long‐distance signal for the regulation of plant phosphate homeostasis
Authors: Pant Bikram Datt , Buhtz Anja , Kehr Julia , Scheible Wolf‐Rüdiger 
Published: February 2008

SummaryThe presence of microRNA species in plant phloem sap suggests potential signaling roles by long‐distance regulation of gene expression. Proof for such a role for a phloem‐mobile microRNA is lacking. Here we show that phosphate (Pi) starvation‐induced microRNA399 (miR399) is present in the phloem sap of two diverse plant species, rapeseed and pumpkin, and levels are strongly and specifically increased in phloem sap during Pi deprivation. By performing micro‐grafting experiments using Arabidopsis, we further show that chimeric plants constitutively over‐expressing miR399 in the shoot accumulate mature miR399 species to very high levels in their wild‐type roots, while corresponding primary transcripts are virtually absent in roots, demonstrating shoot‐to‐root transport. The chimeric plants exhibit (i) down‐regulation of the miR399 target transcript (PHO2), which encodes a critical component for maintenance of Pi homeostasis, in the wild‐type root, and (ii) Pi accumulation in the shoot, which is the phenotype of pho2 mutants, miR399 over‐expressers or chimeric plants with a genetic knock‐out of PHO2 in the root. Hence the transported miR399 molecules retain biological activity. This is a demonstration of systemic control of a biological process, i.e. maintenance of plant Pi homeostasis, by a phloem‐mobile microRNA.
Interplay between MAMP‐triggered and SA‐mediated defense responses
Authors: Tsuda Kenichi , Sato Masanao , Glazebrook Jane , Cohen Jerry D. , Katagiri Fumiaki 
Published: February 2008

SummaryPlants respond to pathogen infection using an innate immune system with at least two distinct recognition mechanisms. One mechanism recognizes microbe‐associated molecular patterns (MAMPs). The other is based on resistance (R) genes and specifically recognizes certain pathogen virulence factors, including those delivered through the type III secretion system (TTSS) of bacteria. Salicylic acid (SA)‐mediated responses are an important part of the R gene‐mediated defense. Substantial overlaps between MAMP‐triggered and SA‐mediated responses have been reported. However, interactions between MAMP‐triggered and SA‐mediated signaling mechanisms have not been well documented. Here we report intimate interactions between MAMP‐triggered and SA‐mediated signaling. We found that SA accumulated at a higher level 6 h after treatment with a MAMP, flg22 or inoculation with Pseudomonas syringae pv. tomato DC3000 (PstDC3000) hrcC mutant, which is deficient in TTSS function. Disruptions of SA signaling components, such as SID2 and PAD4, strongly affected MAMP‐triggered responses monitored by expression profiling. We found two groups of genes that were induced by PstDC3000 hrcC in an SA‐dependent manner. One group was SID2‐dependent at all time points, whereas the other was SID2‐independent at early time points and SID2‐dependent at later time points. Thus, the expression of the latter genes responds to MAMPs through both SA‐independent and SA‐dependent signaling mechanisms. Strong resistance to PstDC3000 hrcC was dependent on SA signaling. These results indicate that the SA increase triggered by MAMPs is a major component of the MAMP‐triggered signaling mechanism, explaining the overlapping spectra of MAMP‐triggered and SA‐mediated responses.
Role of a GDSL lipase‐like protein as sinapine esterase in Brassicaceae
Authors: Clauß Kathleen , Baumert Alfred , Nimtz Manfred , Milkowski Carsten , Strack Dieter 
Published: February 2008

SummaryThe seeds of most members of the Brassicaceae accumulate high amounts of sinapine (sinapoylcholine) that is rapidly hydrolyzed during early stages of seed germination. One of three isoforms of sinapine esterase activity (BnSCE3) has been isolated from Brassica napus seedlings and subjected to trypsin digestion and spectrometric sequencing. The peptide sequences were used to isolate BnSCE3 cDNA, which was shown to contain an open reading frame of 1170 bp encoding a protein of 389 amino acids, including a leader peptide of 25 amino acids. Sequence comparison identified the protein as the recently cloned BnLIP2, i.e. a GDSL lipase‐like protein, which displays high sequence identity to a large number of corresponding plant proteins, including four related Arabidopsis lipases. The enzymes belong to the SGNH protein family, which use a catalytic triad of Ser‐Asp‐His, with serine as the nucleophile of the GDSL motif. The corresponding B. napus and Arabidopsis genes were heterologously expressed in Nicotiana benthamiana leaves and proved to confer sinapine esterase activity. In addition to sinapine esterase activity, the native B. napus protein (BnSCE3/BnLIP2) showed broad substrate specificity towards various other choline esters, including phosphatidylcholine. This exceptionally broad substrate specificity, which is common to a large number of other GDSL lipases in plants, hampers their functional analysis. However, the data presented here indicate a role for the GDSL lipase‐like BnSCE3/BnLIP2 as a sinapine esterase in members of the Brassicaceae, catalyzing hydrolysis of sinapine during seed germination, leading, via 1‐O‐sinapoyl‐β‐glucose, to sinapoyl‐l‐malate in the seedlings.
Expression and functional analysis of AtMUS81 in Arabidopsis meiosis reveals a role in the second pathway of crossing‐over
Authors: Higgins James D. , Buckling Ewen F. , Franklin F. Chris H. , Jones Gareth H. 
Published: February 2008

SummaryMeiotic crossovers/chiasmata, that are required to ensure chromosome disjunction, arise via the class I interference‐dependent pathway or via the class II interference‐free pathway. The proportions of these two classes vary considerably between different organisms. In Arabidopsis, about 85% of chiasmata are eliminated in Atmsh4 mutants, denoting that these are class I events. In budding and fission yeasts Msh4‐independent crossovers arise largely or entirely via a Mus81‐dependent pathway. To investigate the origins of the 15% residual (AtMSH4‐independent) chiasmata in Arabidopsis we conducted a cytological and molecular analysis of AtMUS81 meiotic expression and function. Although AtMUS81 functions in somatic DNA repair and recombination, it is more highly expressed in reproductive tissues. The protein is abundantly present in early prophase I meiocytes, where it co‐localizes, in a double‐strand break‐dependent manner, with the recombination protein AtRAD51. Despite this, an Atmus81 mutant shows normal growth and has no obvious defects in reproductive development that would indicate meiotic impairment. A cytological analysis confirmed that meiosis was apparently normal in this mutant and its mean chiasma frequency was similar to that of wild‐type plants. However, an Atmsh4/Atmus81 double mutant revealed a significantly reduced mean chiasma frequency (0.85 per cell), compared with an Atmsh4 single mutant (1.25 per cell), from which we conclude that AtMUS81 accounts for some, but not all, of the 15% AtMSH4‐independent residual crossovers. It is possible that other genes are responsible for these residual chiasmata. Alternatively the AtMUS81 pathway coexists with an alternative parallel pathway that can perform the same functions.
Natural variation and functional analyses provide evidence for co‐evolution between plant eIF4E and potyviral VPg
Authors: Charron Carine , Nicolaï Maryse , Gallois Jean‐Luc , Robaglia Christophe , Moury Benoît , Palloix Alain , Caranta Carole 
Published: February 2008

SummaryAmino acid substitutions in the eukaryotic translation initiation factor 4E (eIF4E) result in recessive resistance to potyviruses in a range of plant species, including Capsicum spp. Correspondingly, amino acid changes in the central part of the viral genome‐linked protein (VPg) are responsible for the potyvirus’s ability to overcome eIF4E‐mediated resistance. A key observation was that physical interaction between eIF4E and the VPg is required for viral infection, and eIF4E mutations that cause resistance prevent VPg binding and inhibit the viral cycle. In this study, polymorphism analysis of the pvr2‐eIF4E coding sequence in a worldwide sample of 25 C. annuum accessions identified 10 allelic variants with exclusively non‐synonymous variations clustered in two surface loops of eIF4E. Resistance and genetic complementation assays demonstrated that pvr2 variants, each with signature amino acid changes, corresponded to potyvirus resistance alleles. Systematic analysis of the interactions between eIF4E proteins encoded by the 10 pvr2 alleles and VPgs of virulent and avirulent potato virus Y (PVY) and tobacco etch virus (TEV) strains demonstrated that resistance phenotypes arose from disruption of the interaction between eIF4E and VPg, and that viral adaptation to eIF4E‐mediated resistance resulted from restored interaction with the resistance protein. Complementation of an eIF4E knockout yeast strain by C. annuum eIF4E proteins further shows that amino acid changes did not impede essential eIF4E functions. Altogether, these results argue in favour of a co‐evolutionary ‘arms race’ between Capsicum eIF4E and potyviral VPg.
A cyclin‐dependent protein kinase, CDKC2, colocalizes with and modulates the distribution of spliceosomal components in Arabidopsis
Authors: Kitsios Georgios , Alexiou Konstantinos G. , Bush Max , Shaw Peter , Doonan John H. 
Published: February 2008

SummaryCyclin‐dependent kinases (CDKs) play key regulatory roles in diverse cellular functions, including cell‐cycle progression, transcription and translation. In plants, CDKs have been classified into several groups, named A through to G, but the functions of most are poorly characterized. CDKCs are known to phosphorylate the C‐terminal domain (CTD) of RNA polymerase II (RNAP II), and therefore the CDKC‐cyclinT (CycT) complex may have a role similar to the animal CDK9‐CycT complex of the positive transcription elongation factor b (P‐TEFb). However, we found that the predicted structure of the Arabidopsis CDKC2 protein is more similar to the mammalian cdc2‐related kinase, CRK7, than to CDK9. CRK7 is proposed to link transcription with splicing, and CDKC2 contains all the structural features of CRK7 that make the latter distinct from CDK9. Consistent with this, we show that GFP‐CDKC2 fusion proteins co‐localize with spliceosomal components, that the expression of CDKC2 modifies the location of these components, and that co‐localization was dependent on the transcriptional status of the cells and on CDKC2‐kinase activity. We propose, therefore, that the Arabidopsis CDKC2 combines the functions of both CRK7 and CDK9, and could also couple splicing with transcription.
Loss‐of‐function mutations and inducible RNAi suppression of Arabidopsis LCB2 genes reveal the critical role of sphingolipids in gametophytic and sporophytic cell viability
Authors: Dietrich Charles R. , Han Gongshe , Chen Ming , Berg R. Howard , Dunn Teresa M. , Cahoon Edgar B. 
Published: February 2008

SummarySerine palmitoyltransferase (SPT) catalyzes the first step in sphingolipid biosynthesis, and downregulation of this enzyme provides a means for exploring sphingolipid function in cells. We have previously demonstrated that Arabidopsis SPT requires LCB1 and LCB2 subunits for activity, as is the case in other eukaryotes. In this study, we show that Arabidopsis has two genes (AtLCB2a and AtLCB2b) that encode functional isoforms of the LCB2 subunit. No alterations in sphingolipid content or growth were observed in T‐DNA mutants for either gene, but homozygous double mutants were not recoverable, suggesting that these genes are functionally redundant. Reciprocal crosses conducted with Atlcb2a and Atlcb2b mutants indicated that lethality is associated primarily with the inability to transmit the lcb2 null genotype through the haploid pollen. Consistent with this, approximately 50% of the pollen obtained from plants homozygous for a mutation in one gene and heterozygous for a mutation in the second gene arrested during transition from uni‐nucleate microspore to bicellular pollen. Ultrastructural analyses revealed that these pollen grains contained aberrant endomembranes and lacked an intine layer. To examine sphingolipid function in sporophytic cells, Arabidopsis lines were generated that allowed inducible RNAi silencing of AtLCB2b in an Atlcb2a mutant background. Studies conducted with these lines demonstrated that sphingolipids are essential throughout plant development, and that lethality resulting from LCB2 silencing in seedlings could be partially rescued by supplying exogenous long‐chain bases. Overall, these studies provide insights into the genetic and biochemical properties of SPT and sphingolipid function in Arabidopsis.
Origin of Adenohypophysial Lobes and Cells from Rathke’s Pouch in Swiss Albino Mice. Proliferation and Expression of Pitx 2 and Calbindin D28K in Corticotropic and Somatotropic cell Differentiation
Authors: Reyes R. , Martínez S. , González M. , Tramu G. , Bello A. R. 
Published: February 2008

SummaryA developmental study of the adenohypophysis of the mouse was carried out in response to several as yet unanswered questions about its organogenesis and differentiation. The main objectives were to establish the origin of adenohypophysial lobes and cells from the Rathke’s pouch (RP) and elucidate the mechanisms of development and functional differentiation of the gland. Using diverse techniques, the morphological development, proliferation and differentiation were studied in order to delimit different proliferative regions in the RP, and provide a satisfactory explanation for the distribution of each cell type in the adult gland. Combining the proliferation and differentiation studies, corticotropic and somatotropic cells appear to mainly originate from undifferentiated precursors located within each of these proliferative regions. The involvement of transcription factor Pitx 2 and calcium‐binding protein Calbindin D 28K in the differentiation of corticotropic and somatotropic cells is further clarified.
Origin of Adenohypophysial Lobes and Cells from Rathke’s Pouch in Chicken (Gallus gallus) and Japanese Quail (Coturniz coturniz japonica). Expression of Calcium‐Binding Proteins
Authors: Reyes R. , González M. , Bello A. R. 
Published: February 2008

SummaryA histological and immunochemical study of adenohypophysis development in two bird species: chicken (Gallus gallus) and Japanese quail (Coturnix coturnix japonica) was carried out, focussing firstly morphologically on the origin of its different lobes, then secondly on the differentiation of hormone‐producing cells from the adenohypophysial anlage and their involvement in the differentiation of three calcium‐binding proteins. The results of the morphological development study show how the origin of the adenohypophysis in chicken is totally ectodermic, whilst in Japanese quail the endoderm, in the form of Sessel’s pouch, participates in forming the rostral zone of the anterior lobe. After studying the organogenesis and spatio/temporal differentiation of the hormone‐producing cells proceeding from the adenohypophysial anlage, a regionalization model is proposed for the origin of the different lobes and cell types as well as time sequence, fundamentally the origin of cell regionalization in the adult adenohypophysis. In this process, at least in the two bird species studied, the results obtained from expressing the calcium‐binding proteins, calbindin D 28K, calretinin and parvalbumin show a characteristic distribution pattern for each, suggesting distinct functions.
First Report of a Strain of Alternanthera yellow vein virus Infecting Eclipta prostrate (L.) L. (Compositae) in China
Authors: He Z. F. , Mao M. J. , Yu H. , Wang X. M. , Li H. P. 
Published: February 2008

AbstractIn 2005, Eclipta prostrata plants exhibiting yellow vein symptoms were observed in Guangzhou, Guangdong province, China. A virus isolate G8 was cloned from a symptomatic plant. The complete nucleotide sequence of G8 DNA‐A was determined to be 2745 nucleotides, which had typical characteristics of Begomovirus genome organization. The comparison of complete nucleotide sequence of DNA‐A showed that isolate G8 shared the highest sequence identity with Alternanthera yellow vein virus (AlYVV) isolates G38 and Hn51 at 95.9% and 94.3%, respectively. These results show that G8 infecting E. prostrata in Guangdong is a strain of AlYVV.
Nurse‐led 24‐h hotline for patients with chronic obstructive pulmonary disease reduces hospital use and is safe
Authors: Roberts M. M. , Leeder S. R. , Robinson T. D. 
Published: February 2008

AbstractBackground:  Despite recent advances in the management of patients with chronic obstructive pulmonary disease (COPD), interventions to reduce hospitalization have had only modest success. The aim of this study was to report the outcomes of a novel, nurse‐led 24‐h telephone support line (hotline) for patients with COPD.Methods:  Observational study of patients’ use of hotline between September 2002 and November 2004. All patients with COPD referred to a Respiratory Ambulatory Care programme over this period (n = 458) were given access to the hotline. The number and time of calls to the hotline, outcomes of hotline calls and safety of hotline, were assessed. The characteristics of hotline callers and non‐callers were compared using an unpaired Student’s t‐test for normally distributed variables, a χ2 test for categorical variables and a Mann–Whitney test for non‐normally distributed variables.Results:  Over the period studied, 675 calls were made to the hotline by 118 patients and 56% of calls were made after hours. For 78 calls (12%), advice and interventions given by hotline staff averted potential 000 calls by patients/carers. Specific advice about interventions for acute exacerbations of COPD (AECOPD) was given in a further 117 calls (17%). Callers had more severe COPD than non‐callers (worse lung function, lower exercise capacity and higher prescription of home oxygen, all P < 0.05). No adverse events related to use of the hotline were documented.Conclusion:  A nurse‐led 24‐h hotline for patients with COPD is safe, is used by patients and carers and, when used, reduces hospital presentations with AECOPD.