bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stylar glycoproteins bind to S‐RNase in vitro
Authors: Cruz‐Garcia Felipe , Nathan Hancock C. , Kim Donggiun , McClure Bruce 
Published: April 2005

SummaryS‐RNases determine the specificity of S‐specific pollen rejection in self‐incompatible plants of the Solanaceae, Rosaceae, and Scrophulariaceae. They are also implicated in at least two distinct types of unilateral interspecific incompatibility in Nicotiana. However, S‐RNase itself is not sufficient for most types of pollen rejection, and evidence for its direct interaction with pollen tubes is limited. Thus, non‐S‐RNase factors also are required for pollen rejection. As one approach to identifying such factors, we tested whether SC10‐RNase from Nicotiana alata would bind to other stylar proteins in vitro. SC10‐RNase was immobilized on Affi‐gel, and binding proteins were analyzed by SDS‐PAGE and immunoblotting. In addition to SC10‐RNase and a small protein similar to lily chemocyanin, the most prominent binding proteins include NaTTS, 120K, and NaPELPIII, these latter three being arabinogalactan proteins previously shown to interact directly with pollen tubes. We also show that SC10‐RNase and these glycoproteins migrate as a complex in a native PAGE system. Our hypothesis is that S‐RNase forms a complex with these glycoproteins in the stylar ECM, that the glycoproteins interact directly with the pollen tubes and thus that the initial interaction between the pollen tube and S‐RNase is indirect.
A nuclear gene of Chlamydomonas reinhardtii, Tba1, encodes a putative oxidoreductase required for translation of the chloroplast psbA mRNA
Authors: Somanchi Aravind , Barnes Dwight , Mayfield Stephen P. 
Published: April 2005

SummaryBiosynthesis of chloroplast proteins is to a large extent regulated post‐transcriptionally, and a number of nuclear‐encoded genes have been identified that are required for translation or stability of specific chloroplast mRNAs. A nuclear mutant of Chlamydomonas reinhardtii, hf261, deficient in the translation of the psbA mRNA, has reduced association of the psbA mRNA with ribosomes and is deficient in binding of the chloroplast localized poly (A) binding protein (cPAB1) to the psbA mRNA. Cloning of the hf261 locus and complementation of hf261 using a wt genomic clone has identified a novel gene, Tba1, for translational affector of psbA. Strains complemented with the wt Tba1 gene restore the ability of the psbA mRNA to associate with ribosomes, and restores RNA binding activity of cPAB1 for the psbA mRNA. Analysis of the Tba1 gene identified a protein with significant homology to oxidoreductases. The effect of Tba1 expression on the RNA binding activity of cPAB1, and on the association of psbA mRNA with ribosomes, implies that Tba1 functions as a redox regulator of cPAB1 RNA binding activity to indirectly promote psbA mRNA translation initiation. A model of chloroplast translation incorporating Tba1 and other members of the psbA mRNA binding complex is presented.
EDS1 in tomato is required for resistance mediated by TIR‐class R genes and the receptor‐like R gene Ve
Authors: Hu Gongshe , DeHart Amy K.A. , Li Yansu , Ustach Carolyn , Handley Vanessa , Navarre Roy , Hwang Chin‐Feng , Aegerter Brenna J. , Williamson Valerie M. , Baker Barbara 
Published: April 2005

SummaryIn tobacco and other Solanaceae species, the tobacco N gene confers resistance to tobacco mosaic virus (TMV), and leads to induction of standard defense and resistance responses. Here, we report the use of N‐transgenic tomato to identify a fast‐neutron mutant, sun1‐1 (suppressor of N), that is defective in N‐mediated resistance. Induction of salicylic acid (SA) and expression of pathogenesis‐related (PR) genes, each signatures of systemic acquired resistance, are both dramatically suppressed in sun1‐1 plants after TMV treatment compared to wild‐type plants. Application of exogenous SA restores PR gene expression, indicating that SUN1 acts upstream of SA. Upon challenge with additional pathogens, we found that the sun1‐1 mutation impairs resistance mediated by certain resistance (R) genes, (Bs4, I, and Ve), but not others (Mi‐1). In addition, sun1‐1 plants exhibit enhanced susceptibility to TMV, as well as to virulent pathogens. sun1‐1 has been identified as an EDS1 homolog present on chromosome 6 of tomato. The discovery of enhanced susceptibility in the sun1‐1 (Le_eds1‐1) mutant plant, which contrasts to reports in Nicotiana benthamiana using virus‐induced gene silencing, provides evidence that the intersection of R gene‐mediated pathways with general resistance pathways is conserved in a Solanaceous species. In tomato, EDS1 is important for mediating resistance to a broad range of pathogens (viral, bacterial, and fungal pathogens), yet shows specificity in the class of R genes that it affects (TIR‐NBS‐LRR as opposed to CC‐NBS‐LRR). In addition, a requirement for EDS1 for Ve‐mediated resistance in tomato exposes that the receptor‐like R gene class may also require EDS1.
The pvr1 locus in Capsicum encodes a translation initiation factor eIF4E that interacts with Tobacco etch virus VPg
Authors: Kang Byoung‐Cheorl , Yeam Inhwa , Frantz James D. , Murphy John F. , Jahn Molly M. 
Published: April 2005

SummaryMutations in the eIF4E homolog encoded at the pvr1 locus in Capsicum result in broad‐spectrum potyvirus resistance attributed to the pvr1 resistance allele, a gene widely deployed in agriculture for more than 50 years. We show that two other resistance genes, previously known to be eIF4E with narrower resistance spectra, pvr21 and pvr22, are alleles at the pvr1 locus. Based on these data and current nomenclature guidelines, we have re‐designated these alleles, pvr11 and pvr12, respectively. Point mutations in pvr1, pvr11, and pvr12 grouped to similar regions of eIF4E and were predicted by protein homology models to cause conformational shifts in the encoded proteins. The avirulence determinant in this potyvirus system has previously been identified as VPg, therefore yeast two‐hybrid and GST pull‐down assays were carried out with proteins encoded by the pvr1 alleles and VPg from two different strains of Tobacco etch virus (TEV) that differentially infected Capsicum lines carrying these genes. While the protein encoded by the susceptible allele pvr1+ interacted strongly, proteins translated from all three resistance alleles (pvr1, pvr11, and pvr12) failed to bind VPg from either strain of TEV. This failure to bind correlated with resistance or reduced susceptibility, suggesting that interruption of the interaction between VPg and this eIF4E paralog may be necessary, but is not sufficient for potyvirus resistance in vivo. Among the three resistance alleles, only the pvr1 gene product failed to bind m7‐GTP cap‐analog columns, suggesting that disrupted cap binding is not required for potyvirus resistance.
SIPK signaling controls multiple components of harpin‐induced cell death in tobacco
Authors: Samuel Marcus A. , Hall Hardy , Krzymowska Magdalena , Drzewiecka Kinga , Hennig Jacek , Ellis Brian E. 
Published: April 2005

SummaryHarpin from Pseudomonas syringae pv. phaseolicola (HrpZ) elicits a rapid cell death response in tobacco plants. Multiple signaling components, including mitogen‐activated protein kinase (MAPK), reactive oxygen species (ROS) and salicylic acid (SA), have been reported to be involved in this cell death process, but the interaction between these molecules is poorly understood. Here we show through utilizing plants manipulated in SIPK expression levels that lack of SIPK results in increased sensitivity to harpin with concomitant accumulation of higher levels of ROS. Conversely, SIPK‐overexpressing plants show reduced sensitivity to harpin relative to wild‐type plants, and display reduced ROS accumulation. Harpin‐induced cell death was found to be conditional on the ability of the plant to accumulate SA, whereas harpin induction of MAPK activation and ROS accumulation are not. However, harpin‐induced ROS accumulation is required for activation of SIPK and wound‐induced protein kinase. Transcriptional profiling revealed that suppression of SIPK signaling also affects early expression of a range of pathogen‐ and stress‐responsive genes during harpin challenge.
Staphylococcus aureus pathogenicity on Arabidopsis thaliana is mediated either by a direct effect of salicylic acid on the pathogen or by SA‐dependent, NPR1‐independent host responses
Authors: Prithiviraj Balakrishnan , Bais Harsh P. , Jha Ajay K. , Vivanco Jorge M. 
Published: April 2005

Summary Staphylococcus aureus is a ubiquitous gram‐positive bacterium that can cause superficial to serious systemic infections in animals and humans. Here we report the development of a plant infection model to study the pathogenesis of this bacterium. Three global regulatory mutants, RN6911 (agr−), ALC 488 (sarA−) ALC 842 (sarA−/agr−) and an alpha‐toxin mutant defective in biofilm formation (DU1090) which are attenuated in animal pathogenesis, were also attenuated in their ability to infect plants, suggesting that these regulators that mediate synthesis of virulence factors essential for animal pathogenesis are also required for plant pathogenesis. Further, using Arabidopsis plants altered in defense responses such as the transgenic lines NahG [defective in salicylic acid (SA) accumulation], and 35S‐LOX2(−) (defective in jasmonic acid production and hyper‐accumulator of SA), and mutants ics1 (depleted in SA accumulation), and npr1‐1 (non‐expressor of pathogenesis‐related protein) we show that resistance of Arabidopsis to typical plant pathogens and the animal pathogen S. aureus is conserved and is mediated by SA. The data presented here suggest that Arabidopsis thaliana resistance to S. aureus is mediated either by a direct effect of SA on the pathogen, specifically one that affects the attachment/aggregate formation on the root surface and reduces the pathogen's virulence, or by SA‐dependent, NPR1‐independent host responses.
Marking cell lineages in living tissues
Authors: Kurup Smita , Runions John , Köhler Uwe , Laplaze Laurent , Hodge Sarah , Haseloff Jim 
Published: April 2005

SummaryWe have generated a novel genetic system to visualize cell lineages in living tissues at high resolution. Heat shock was used to trigger the excision of a specific transposon and activation of a fluorescent marker gene. A histone‐YFP marker was used to allow identification of cell lineages and easy counting of cells. Constitutive expression of a green fluorescent membrane protein was used to provide a precise outline of all surrounding cells. Marked lineages can be induced from specific cells within the organism by targeted laser irradiation, and the fate of the marked cells can be followed non‐invasively. We have used the system to map cell lineages originating from the initials of primary and lateral roots in Arabidopsis. The lineage marking technique enabled us to measure the differential contribution of primary root pericycle cell files to developing lateral root primordia. The majority of cells in an emerging lateral root primordium derive from the central file of pericycle founder cells while off‐centre founder cells contribute only a minor proliferation of tissue near the base of the root. The system shows great promise for the detailed study of cell division during morphogenesis.
Corridors in Real Landscapes: A Reply to Simberloff and Cox
Authors: NOSS REED F. 
Published: April 2005

Abstract: Habitat corridors have become popular in land‐use plans and conservation strategies, yet few data are available to either support or refute their value. Simberloff and Cox (1987) have criticized what they consider an uncritical acceptance of corridors in conservation planning.Any reasonable conservation strategy must address the overwhelming problem of habitat fragmentation. Although Simberloff and Cox use island analogies to illustrate advantages of isolation, these analogies do not apply directly to problems in landscape planning. Genetics also does not offer unequivocal advice, but the life histories of wide‐ranging animals (eg., the Florida panther) suggest that the maintenance or restoration of connectivity in the landscape is a prudent strategy. Translocation of individuals among reserves—considered by Simberloff and Cox a viable alternative to natural dispersal—is impractical for whole communities of species that are likely to suffer from problems related to fragmentation.Many of the potential disadvantages of corridors could be avoided or mitigated by enlatging cowidor width or by applying ecologically sound zoning regulations. Corridors are not the solution to all of our conservation problems, nor should they be used as a justification for small reserves. But corridors can be a cost‐effective complement to the strategy of large and multiple reserves in real‐life landscapes.
The Principle of Nested Subsets and Its Implications for Biological Conservation
Authors: PATTERSON BRUCE D. 
Published: April 2005

Abstract: The nested subset hypothesis states that the species comprising a depauperate insular biota are a proper subset of those in richer biotas, and that an archipelago of such biotas, ranked by species richness, presents a nested series. The pattern characterizes the distributions of mammals in three different archipelagos, and it appears more strongly developed among faunas in the process of, relaxation (landbridge islands) than in those derived by overwater colonization (oceanic islands). The generality of the nested subset pattern and factors that may produce it are evaluated using distributions of land birds in the New Zealand region. Monte Carlo simulations show that species composition of these insular avifaunas is highly nonrandom, exhibiting significantly nested structure. However, avifaunas on nine oceanic islands lack the structure typical of all islands together or of the 22 landbridge islands. Thus, distinctive patterns of species composition, as well as species number, may distinguish landbridge and oceanic islands.Because they are isolated fragments of once‐continuous distributions, landbridge islands and their biotas have important implications for long‐term biological conservation in preserves. Real or virtual islands that have undergone faunal relaxation support only a fraction of the species expected in equivalent mainland areas. Furthermore, the species inhabiting fragments are not a random collection of those in the source pool, but are rather nested subsets of the species in richer, more intact biotas. The species preserved in such fragments tend to be the most abundant, generalist species that are least in need of special protection.
Conservation and Distribution of Genetic Variation in a Polytypic Species, the Cutthroat Trout
Authors: ALLENDORF FRED W. , LEARY ROBB F. 
Published: April 2005

Abstract: The cutthroat trout (Salmo clarki) presents a series of unusual and difficult problems in conservation biology. As many as 16 subspecies have been recognized in the recent literature. The genetic distance between subspecies based upon 46 enzyme loci ranges from that usually seen between congeneric species to virtual genetic identity. Subspecies from the western portion of the range of the cutthroat trout are genetically more similar to rainbow trout (Salmo gairdneri) than they are to the other subspecies of cutthroat trout. In addition, much of the genetic variation within the west‐slope cutthroat trout (S. c. lewisi) results from alleles found in only one or two local populations, but they often occur at high frequencies in those populations. Thus, preserving the genetic variation in westslope cutthroat trout entails preserving as many local populations as possible.Captive populations of cutthroat trout present a series of opportunities and genetic problems. A number of management agencies are using captive populations to supplement and reestablish natural populations. Basic genetic principles must be understood and followed in establishing and maintaining captive populations. We describe examples of unsuccessful and successful efforts by management agencies to develop captive populations.The greatest danger to the conservation of the cutthroat trout is introgressive hybridization among subspecies and with rainbow trout. Several factors make salmonid fishes especially susceptible to problems associated with introgressive hybridization. We conclude that biochemical analysis provides a more reliable and informative means of detecting interbreeding than morphological characters. Interbreeding between westslope and Yellowstone cutthroat trout and nonnative Salmo appears to be common and widespread throughout the natural range of these subspecies.
The Impact of Infection and Disease on Animal Populations: Implications for Conservation Biology
Authors: SCOTT MARILYN E. 
Published: April 2005

Abstract:The distinction between infection and disease may be subtle, and detection of disease in wild animal populations depends on the sophistication of sampling design and diagnostic techniques used in examining animal populations. The impact of infection on the host is dependent not only on the pathogenicity of the infection but also on the interactions between infection and other factors such as nutritional status and stress. In this paper I review mechanisms by which parasitic infections can influence the survival, reproduction, and movement patterns of infected individuals. I then discuss the implications for host populations, in particular with reference to the potential of parasites to regulate the abundance of host populations. The implications of infection and disease on host populations are then extended to demonstrate consequences on community structure. Difficulties associated with assessing the level of infection or disease in wild animal populations are discussed and used to account for the frequently held belief that disease rarely occurs in wild animal populations. Finally, the consequences of infection and disease for conservation biology are outlined. Disease is considered with regard to introductions and maintenance of genetic diversity. Emphasis is placed on the dangers associated with forcing animals into high‐density situations. High host densities lead directly to increased disease because of increased transmission rates, and also indirectly increase disease because of synergistic interactions between infection, reduced nutritional status of the host population, and increased stress all associated with high‐density situations. I recommend a surveillance program for monitoring prevalence or intensity in selected indicator age classes as a first step for preventing major disease problems in animal populations. I conclude that infection and disease will be an important determinant of the health and well‐being of animal populations, and as such must be considered in the design of conservation policy.
A Preliminary Assessment of the Status of Major Terrestrial and Wetland Ecosystems on Federal and Indian Lands in the United States
Authors: CRUMPACKER DAVID W. , HODGE STEPHEN W. , FRIEDLEY DALE , GREGG WILLIAM P. 
Published: April 2005

Abstract:Major terrestrial and wetland ecosystems in the United States were described by 135 Küchler potential natural vegetation (PNV) types. Their occurrence on federal and Indian lands was then determined by computer overlay of PNV maps on the National Geographic Society's 1982 map of America's Federal Lands. Based on the map scales used it was determined that at least 33 of 135 PNV types (24%) are inadequately represented on federal and Indian lands. Nine of the 33 have no representation. Eleven others have relatively little representation and are either naturally rare or have been largely converted to nonnatural uses. All federal agencies and the Indian lands have large gaps in their ecosystem coverage. Among agencies with nationwide land management systems and strong conservation mandates, the percentage of major ecosystem types with no apparent representation on these agenlands is: US Forest Service, 27 percent; National Park Service, 33 percent; and U.S. Fish and Wildlife Service, 53 percent. The Bureau of Land Management, Department of Defense, and Indian lands collectively play an important role in supplementing the current coverage of the other agencies.Because of inaccuracies associated with the small‐scale maps that were analyzed and the nature of PNV types, these results are preliminary and should be used only for general planning. Inclusion of a PNV type within a management unit, based on map overlay, does not ensure that mature vegetation representative of that type actually is present on the ground Additional assessments would have to be made to determine the type and health of existing vegetation within the mil, as well as the amount of future protection that the unit would be expected to provide.Cooperation among federal, state, and local agencies and private organizations is needed to provide a cost‐effective program of national ecosystem Conservation. More detailed state and regional surveys can be used to improve the accuracy of this preliminary national survey.
Effects of Introduced Plants and Animals on Island Vegetation: Examples from Galápagos Archipelago
Authors: SCHOFIELD EILEEN K 
Published: April 2005

Abstract:Island ecosystems are particularly vulnerable to biological invasions. Since the early 1800s, humans have introduced to the Galápagos Islands animals and plants that threaten the native vegetation Goats are the most abundant and destructive feral animals. Endemic members of the Cactaceae and Asteraceae have been reduced drastically. A control program has completely eradicated goats on several islands, where vegetation has returned but sometimes the species composition differs from the original. Hunting continues on Santiago, where 80,000 goats exist, and fenced quadrats protect some native plants. Cattle damage vegetation, particularly the endemic shrub, Miconia robinsoniana, by trampling and grazing. Ranchers on several islands have been urged to fence in cattle. Wild pigs dig up and eat the roots of woody plants and some rare orchids. Donkeys trample and eat grasses and shrubs. Control of pigs has started; there is no control of donkeys. Between 20 and 50 introduced plants have escaped cultivation and invaded the native vegetation. Guava is the most widespread, covering vast areas on several islands. Its dispersal is aided by free‐roaming cattle, which eat the fruits and excrete the seeds. Quinine trees have spread extensively on one island via windblown seeds. Both species are being cut down, and herbicides are applied to trunks to prevent sprouting. Other aliens that are problems on one or more islands include lantana, hemp, avocado, sweet lime, and forage grasses. None of these is being eliminated yet, because of lack of funds and manpower. To ensure the future of the Galápagos flora, control measures must continue and expand to encompass all dangerous introductions.