bluuebunny/crossref_metadata_2025 huggingface dataset:
Three Reasons Not to Believe in an Autism Epidemic
Authors: Gernsbacher Morton Ann , Dawson Michelle , Hill Goldsmith H.
Published: August 2005

According to some lay groups, the nation is experiencing an autism epidemic—a rapid escalation in the prevalence of autism for unknown reasons. However, no sound scientific evidence indicates that the increasing number of diagnosed cases of autism arises from anything other than purposely broadened diagnostic criteria, coupled with deliberately greater public awareness and intentionally improved case finding. Why is the public perception so disconnected from the scientific evidence? In this article we review three primary sources of misunderstanding: lack of awareness about the changing diagnostic criteria, uncritical acceptance of a conclusion illogically drawn in a California-based study, and inattention to a crucial feature of the “child count” data reported annually by the U.S. Department of Education.
Buddhist and Psychological Perspectives on Emotions and Well-Being
Authors: Ekman Paul , Davidson Richard J. , Ricard Matthieu , Alan Wallace B.
Published: August 2005

Stimulated by a recent meeting between Western psychologists and the Dalai Lama on the topic of destructive emotions, we report on two issues: the achievement of enduring happiness, what Tibetan Buddhists call sukha, and the nature of afflictive and nonafflictive emotional states and traits. A Buddhist perspective on these issues is presented, along with discussion of the challenges the Buddhist view raises for empirical research and theory.
Resilience and Vulnerability to Daily Stressors Assessed via Diary Methods
Authors: Almeida David M.
Published: August 2005

Stressors encountered in daily life, such as family arguments or work deadlines, may play an important role in individual health and well-being. This article presents a framework for understanding how characteristics of individuals and their environments limit or increase exposure and reactivity to daily stressors. Research on daily stressors has benefited from diary methods that obtain repeated measurements from individuals during their daily lives. These methods improve ecological validity, reduce memory distortions, and permit the assessment of within-person processes. Findings from the National Study of Daily Experiences, which used a telephone-diary design, highlight how people's age, gender, and education and the presence or absence of chronic stressors in their lives predict their exposure and reactivity to daily stressors. Finally, future directions for research designs that combine laboratory-based assessment of stress physiology with daily-diary methods are discussed.
Language and Children's Understanding of Mental States
Authors: Harris Paul L. , de Rosnay Marc , Pons Francisco
Published: August 2005

Children progress through various landmarks in their understanding of mind and emotion. They eventually understand that people's actions, utterances, and emotions are determined by their beliefs. Although these insights emerge in all normal children, individual children vary in their rates of progress. Four lines of research indicate that language and conversation play a role in individual development: (a) Children with advanced language skills are better at mental-state understanding than those without advanced language skills, (b) deaf children born into nonsigning families lag in mental-state understanding, and (c) exposure to maternal conversation rich in references to mental states promotes mental-state understanding, as do (d) experimental language-based interventions. Debate centers on the mechanism by which language and conversation help children's understanding of mental states. Three competing interpretations are evaluated here: lexical enrichment (the child gains from acquiring a rich mental-state vocabulary), syntactic enrichment (the child gains from acquiring syntactic tools for embedding one thought in another), and pragmatic enrichment (the child gains from conversations in which varying perspectives on a given topic are articulated). Pragmatic enrichment emerges as the most promising candidate.
Regulating the Risks of Closeness
Authors: Murray Sandra L.
Published: August 2005

To feel secure in romantic relationships, people need to believe that their partners see qualities in them that merit attention, nurturance, and care. This article examines how finding (or failing to find) this sense of security affects three facets of romantic life: (a) the inferences people draw about their partners' regard for them in threatening situations, (b) the inferences people draw about their own value in situations in which they feel rejected, and (c) the kinds of behavioral strategies (whether protective of the self or promotive of the relationship) that people adopt to minimize the likelihood of feeling hurt or rejected again.
A Basic-Systems Approach to Autobiographical Memory
Authors: Rubin David C.
Published: August 2005

Memory for complex everyday events involving vision, hearing, smell, emotion, narrative, and language cannot be understood without considering the properties of the separate systems that process and store each of these forms of information. Using this premise as a starting point, my colleagues and I found that visual memory plays a central role in autobiographical memory: The strength of recollection of an event is predicted best by the vividness of its visual imagery, and a loss of visual memory causes a general amnesia. Examination of autobiographical memories in individuals with posttraumatic stress disorder (PTSD) suggests that the lack of coherence often noted in memories of traumatic events is not due to a lack of coherence either of the memory itself or of the narrative that integrates the memory into the life story. Rather, making the traumatic memory central to the life story correlates positively with increased PTSD symptoms. The basic-systems approach has yielded insights into autobiographical memory's phenomenology, neuropsychology, clinical disorders, and neural basis.
Does Damage to the Frontal Lobes Produce Impairment in Memory?
Authors: Stuss Donald T. , Alexander Michael P.
Published: August 2005

There has long been controversy about the function of the frontal lobes in memory. Historically, in lesion studies, the frontal lobes were discussed as if they represented a single functional unit, and little attention was paid to possible regional differences. In a series of experiments involving patients with focal frontal lobe lesions, we have demonstrated that different frontal regions affect strategic memory processes in unique ways. In addition, some regions of the frontal lobes are involved in nonstrategic memory encoding, likely through actual involvement of the limbic memory regions or through the impact of processing deficits related to the specific mode of the information to be learned (e.g., language). These findings converge with those of functional imaging studies showing the dissociation of memory processes within the frontal lobes, and are indicative of the complex roles subserved by the frontal lobes. Future research will need to explore how the different functions within the frontal lobes influence other dynamic cognitive systems.
Current Trends and Future Directions in the Study of Psychosocial Treatments for Pathological Gambling
Authors: Ledgerwood David M. , Petry Nancy M.
Published: August 2005

Pathological gambling is a psychiatric disorder that has considerable public-health implications. Promising treatments for pathological gambling have been identified. However, most treatment research is limited by methodological problems that preclude drawing conclusions about treatment efficacy. We explore the empirical evidence for some currently practiced treatments for pathological gambling. We also discuss some of the challenges and future directions for research on how to treat the disorder.
Item Response Theory
Authors: Reise Steven P. , Ainsworth Andrew T. , Haviland Mark G.
Published: August 2005

Item response theory (IRT) is an increasingly popular approach to the development, evaluation, and administration of psychological measures. We introduce, first, three IRT fundamentals: (a) item response functions, (b) information functions, and (c) invariance. We next illustrate how IRT modeling can improve the quality of psychological measurement. Available evidence suggests that the differences between IRT and traditional psychometric methods are not trivial; IRT applications can improve the precision and validity of psychological research across a wide range of subjects.
Understanding Popularity in the Peer System
Authors: Cillessen Antonius H.N. , Rose Amanda J.
Published: August 2005

Much research has focused on youth who are rejected by peers; who engage in negative behavior, including aggression; and who are at risk for adjustment problems. Recently, researchers have become increasingly interested in high-status youth. A distinction is made between two groups of high-status youth: those who are genuinely well liked by their peers and engage in predominantly prosocial behaviors and those who are seen as popular by their peers but are not necessarily well liked. The latter group of youth is well known, socially central, and emulated, but displays a mixed profile of prosocial as well as aggressive and manipulative behaviors. Research now needs to address the distinctive characteristics of these two groups and their developmental precursors and consequences. Of particular interest are high-status and socially powerful aggressors and their impact on their peers. The heterogeneity of high-status youth complicates the understanding of the social dynamics of the peer group, but will lead to new and important insights into the developmental significance of peer relationships.
Implicit Egotism
Authors: Pelham Brett W. , Carvallo Mauricio , Jones John T.
Published: August 2005

People gravitate toward people, places, and things that resemble the self. We refer to this tendency as implicit egotism, and we suggest that it reflects an unconscious process that is grounded in people's favorable self-associations. We review recent archival and experimental research that supports this position, highlighting evidence that rules out alternate explanations and distinguishes implicit egotism from closely related ideas such as mere exposure. Taken together, the evidence suggests that implicit egotism is an implicit judgmental consequence of people's positive self-associations. We conclude by identifying promising areas for future research.
Out of Balance
Authors: Robles Theodore F. , Glaser Ronald , Kiecolt-Glaser Janice K.
Published: August 2005

Chronic stress is typically associated with suppression of the immune system, including impaired responses to infectious disease and delayed wound healing. Recent work suggests that stress and depression can enhance production of proinflammatory cytokines, substances that regulate the body's immune response to infection and injury. We provide a broad framework relating stress and depression to a range of diseases whose onset and course may be influenced by proinflammatory cytokines, particularly the cytokine interleukin-6 (IL-6). IL-6 has been linked to a spectrum of chronic diseases associated with aging. Production of proinflammatory cytokines that influence these and other conditions can be directly stimulated by chronic stress and depression. We suggest that a key pathway through which chronic stress and depression influence health outcomes involves proinflammatory cytokines. We discuss the evidence for relationships between psychosocial factors and proinflammatory cytokines, and important health implications of these findings.
A general biophysical model of larval cod (Gadus morhua) growth applied to populations on Georges Bank
Authors: LOUGH R. G. , BUCKLEY L. J. , WERNER F. E. , QUINLAN J. A. , PEHRSON EDWARDS K.
Published: August 2005

Field‐derived growth rates (RNA‐DNA based) of cod (Gadus morhua) larvae collected on the southern flank of Georges Bank were higher on average in May 1993 than May 1994, despite the apparent higher abundance of potential prey in 1994. A biophysical modeling study is presented here in which factors are examined that may have led to the difference in population mean growth. A one‐dimensional physical model, forced by winds and tides, was used to simulate the vertical structure (of currents, temperature field, and turbulent kinetic energy dissipation rate) following a column of water in a Lagrangian sense at a site on the southern flank of Georges Bank over 5‐day periods in late May of 1993 and 1994. The biophysical model and observed zooplankton abundance allowed us to explore the vertical structure and temporal (hourly) evolution of feeding and growth for cod larvae in relation to environmental conditions. Our trophodynamic model is improved over previous versions and now includes the effect of light on larval feeding response, as well as the effect of temperature on larval metabolic costs, ingestion, and digestion. Larval prey profiles, comprising four copepod species, were used from a time series of 1/4‐m2 MOCNESS tows to define the prey field. Data from a collateral time‐series of larval gut contents (1‐m2 MOCNESS tows) was used to define maximum ingestion (satiation level) and prey selection. Model outputs provide depth‐dependent estimates of growth, prey biomass ingested, larval length, and larval weight. Water‐column growth‐rate profiles were made for four size classes of larvae (5, 6, 7 and 9 mm) under the environmental conditions observed in May 1993 and 1994. A weighted‐mean growth rate based on the mean vertical distribution of larvae was estimated for each size class. In all cases, when using all available potential prey, the model‐derived 1994 growth rates were higher (by 3–6% day−1) than those for 1993. However, simulations in which 7‐mm larvae followed the field‐derived weighted mean depth over the sampling period, and were limited to their preferred Pseudocalanus prey, resulted in average growth of 12.2% day−1 for 1993 and 9.7% day−1 for 1994. These compared closely to the field growth means of 11.3% day−1 in 1993 and 9.8% day−1 in 1994. Thus, the lower observed growth in May 1994 may have resulted from depth‐dependent food limitation and prey‐selectivity coupled with the greater metabolic costs induced by the higher temperature that year.
Environmental effects on recruitment and productivity of Japanese sardine Sardinops melanostictus and chub mackerel Scomber japonicus with recommendations for management
Authors: YATSU AKIHIKO , WATANABE TOMOWO , ISHIDA MINORU , SUGISAKI HIROYA , JACOBSON LARRY D.
Published: August 2005

We compared a wide range of environmental data with measures of recruitment and stock production for Japanese sardine Sardinops melanostictus and chub mackerel Scomber japonicus to examine factors potentially responsible for fishery regimes (periods of high or low recruitment and productivity). Environmental factors fall into two groups based on principal component analyses. The first principal component group was determined by the Pacific Decadal Oscillation Index and was dominated by variables associated with the Southern Oscillation Index and Kuroshio Sverdrup transport. The second was led by the Arctic Oscillation and dominated by variables associated with Kuroshio geostrophic transport. Instantaneous surplus production rates (ISPR) and log recruitment residuals (LNRR) changed within several years of environmental regime shifts and then stabilized due, we hypothesize, to rapid changes in carrying capacity and relaxation of density dependent effects. Like ISPR, LNRR appears more useful than fluctuation in commercial catch data for identifying the onset of fishery regime shifts. The extended Ricker models indicate spawning stock biomass and sea surface temperatures (SST) affect recruitment of sardine while spawning stock biomass, SST and sardine biomass affect recruitment of chub mackerel. Environmental conditions were favorable for sardine during 1969–87 and unfavorable during 1951–67 and after 1988. There were apparent shifts from favorable to unfavorable conditions for chub mackerel during 1976–77 and 1985–88, and from unfavorable to favorable during 1969–70 and 1988–92. Environmental effects on recruitment and surplus production are important but fishing effects are also influential. For example, chub mackerel may have shifted into a new favorable fishery regime in 1992 if fishing mortality had been lower. We suggest that managers consider to shift fishing effort in response to the changing stock productivity, and protect strong year classes by which we may detect new favorable regimes.
The influence of life history dynamics and environment on the determination of year class strength in North Sea herring (Clupea harengus L.)
Authors: NASH R. D. M. , DICKEY‐COLLAS M.
Published: August 2005

The inter‐annual variability in year class strength (1976–2000) of North Sea herring (Clupea harengus) was investigated using Paulik diagrams based on survey data and Virtual Population Analysis. The herring life cycle was split into five stages: spawning stock biomass (SSB), egg production, larvae, fish with 0 winter rings on the otolith (0‐wr), 1‐wr and 2‐wr. Surveys were used as indices and Paulik analysis revealed relationships between stages. In 80% of the years, year class strength reflected SSB. Poorer than expected year classes were determined during the larva to 0‐wr phase, whilst stronger than expected year classes were apparently determined during the 0‐wr to 1‐wr stage. There was no clear relationship between survival of young stages of herring and the abundance of Calanus finmarchicus but the year class strength of 0‐wr and 1‐wr had a negative relationship to bottom water temperature. Lower sea water temperatures in the North Sea are associated with higher Calanus abundance. The analysis shows that the strength of aberrant year classes of North Sea herring is determined between the pelagic larval and the juvenile stages.
Historical changes in the abundance and distribution of ovigerous red king crabs (Paralithodes camtschaticus) in Bristol Bay (Alaska), and potential relationship with bottom temperature
Authors: LOHER T. , ARMSTRONG D. A.
Published: August 2005

Distribution and abundance of ovigerous female red king crabs (Paralithodes camtschaticus) in the southeast Bering Sea from 1975 to 2001 were investigated using data collected during National Marine Fisheries Service annual trawl surveys. Peak abundance of ∼140 million crabs was observed in 1978, and declined rapidly to a low of just over 6 million in 1986. Abundance fluctuated from ∼6 to 22 million from the late 1980s through 2001, with a single strong recruitment event that resulted in ∼35 million ovigerous females observed in 1998. Changes in abundance were accompanied by changes in distribution. During the late 1970s the population was typified by high abundance to the southwest, along the northern shore of Unimak Island and the Alaska Peninsula. By the mid‐1980s the population's average center of abundance shifted substantially to the northeast and was found in central Bristol Bay. The distribution remained similar throughout the 1990s. Changes in distribution during the late 1970s and early 1980s coincided with changes in early summer near‐bottom temperature. The 1970s were typified by a pool of very cold water (<1°C) within central Bristol Bay. This retreated in ∼1978, and was not observed in consecutive summers during the remainder of the time series. The northeastward shift in the population, measured as the distance between Unimak Pass and the average center of abundance, showed a negative correlation with the geographic extent the cold‐pool. Abundance calculated for smaller spatial strata indicate that changes in distribution were not simply the result of relative abundance phenomena or solely generated by mortality in southwestern Bristol Bay, but also reflected regional increases in absolute abundance. Total broodstock abundance declined after 1978, but abundance in the western and northern areas of the region increased until at least 1982. The fact that distribution patterns change over time may have implications for population dynamics and fishery management. Changes in spatial population structure may affect recruitment patterns via changes in larval dynamics, and management might benefit if the causes of geographic displacement can be identified and predicted.
Early‐ to late‐summer population growth and prey consumption by age‐0 pollock (Theragra chalcogramma), in two years of contrasting pollock abundance near the Pribilof Islands, Bering Sea
Authors: WINTER ANDREAS , SWARTZMAN GORDON , CIANNELLI LORENZO
Published: August 2005

Acoustic survey data were used to estimate the abundance and distribution of age‐0 walleye pollock and zooplankton near the Pribilof Islands, Bering Sea, nursery area at two time periods in two consecutive years: the beginning of August, and mid‐September, of 1996 and 1997. The 1996 pollock year class ultimately produced a large adult cohort in the eastern Bering Sea, while the 1997 year class produced a below‐average adult cohort. Acoustic densities of age‐0 pollock were significantly lower in August – and declined more strongly from August to September – in 1997 than in 1996, indicating that the trend to adult cohort strength was already set by August. Diet composition analyses revealed that age‐0 pollock ate a much higher proportion of euphausiids in 1997 than in 1996, despite lower acoustic abundance of euphausiids in 1997. We infer that in 1996, age‐0 pollock experienced greater feeding success by August, with high concentrations of copepods available for smaller fish to consume, and high concentrations of euphausiids available for larger individuals. In 1997, age‐0 pollock had lower body condition in August and may have been limited by the availability of small (<2 mm) copepods. Bioenergetic modeling of prey consumption did not indicate a likelihood that age‐0 pollock would begin to deplete euphausiids until late August in 1996, and not at all between August and mid‐September in 1997.
Two adjacent nuclear genes are required for functional complementation of a chloroplast trans‐splicing mutant from Chlamydomonas reinhardtii
Authors: Balczun Carsten , Bunse Astrid , Hahn Daniela , Bennoun Pierre , Nickelsen Jörg , Kück Ulrich
Published: August 2005

The chloroplast tscA gene from Chlamydomonas reinhardtii encodes a co‐factor RNA that is involved in trans‐splicing of exons 1 and 2 of the psaA mRNA encoding a core polypeptide of photosystem I. Here we provide molecular and genetic characterization of the trans‐splicing mutant TR72, which is defective in the 3′‐end processing of the tscA RNA and consequently defective in splicing exons 1 and 2 of the psaA mRNA. Using genomic complementation, two adjacent nuclear genes were identified, Rat1 and Rat2, that are able to restore the photosynthetic growth of mutant TR72. Restoration of the photosynthesis phenotype, however, was successful only with a DNA fragment containing both genes, while separate use of the two genes did not rescue the wild‐type phenotype. This was further confirmed by using a set of 10 gene derivatives in complementation tests. The deduced amino acid sequence of Rat1 shows significant sequence homology to the conserved NAD+‐binding domain of poly(ADP‐ribose) polymerases of eukaryotic organisms. However, mutagenesis of conserved residues in this putative NAD+‐binding domain did not reveal any effect on restoration efficiency. Immunodetection analyses with enriched fractions of chloroplast proteins indicated that Rat1 is associated with chloroplast membranes. Using the yeast three‐hybrid system, we were able to demonstrate the specific binding of tscA RNA by the Rat1 polypeptide. We propose that the two nuclear factors Rat1 and Rat2 are involved in processing of chloroplast tscA RNA and in subsequent splicing of psaA exons 1 and 2.
Telomerase‐independent cell survival in Arabidopsis thaliana
Authors: Matthew Watson J. , Bulankova Petra , Riha Karel , Shippen Dorothy E. , Vyskot Boris
Published: August 2005

Telomerase is the reverse transcriptase responsible for the maintenance of telomeric repeat sequences in most species that have been studied. Inactivation of telomerase causes telomere shortening and results in the loss of the telomere's protective function, which in mammals leads to cell‐cycle arrest and apoptosis. Experiments performed on Arabidopsis thaliana mutants lacking telomerase activity revealed their unusually high tolerance for genome instability. Here we present molecular and cytogenetic analysis of two cell lines (A and B) derived from seeds of late‐generation telomerase‐deficient A. thaliana. These cultures have survived for about 3 years and are still viable. However, neither culture has adapted mechanisms to maintain terminal telomeric repeats. One culture (B) suffers from severe growth irregularities and a high degree of mortality. Karyological analysis revealed dramatic genomic rearrangements, a large variation in ploidy, and an extremely high percentage of anaphase bridges. The second cell line (A) survived an apparent crisis and phenotypically appears wild‐type with respect to growth and morphology. Despite these indications of genome stabilization, a high percentage of anaphase bridges was observed in the A line. We conclude that the restructured chromosome termini provide the A line with partial protection from end‐joining repair activities, thus allowing normal growth.
Transgene‐triggered, epigenetically regulated ectopic expression of a flower homeotic gene pMADS3 in Petunia
Authors: Kapoor Meenu , Baba Akiko , Kubo Ken‐ichi , Shibuya Kenichi , Matsui Keisuke , Tanaka Yoshikazu , Takatsuji Hiroshi
Published: August 2005

pMADS3 is a class C floral homeotic gene of Petunia that is specifically expressed in stamens and carpels of developing flowers. We previously reported that introduction of a part of the pMADS3 genomic sequence silenced endogenous pMADS3 (sil‐pMADS3) in transgenic Petunia hybrida. Here we report that introduction of the same sequence triggers ectopic expression of endogenous pMADS3 in sepals, petals and leaves (ect‐pMADS3), accompanied by homeotic conversion of the floral organs and altered leaf morphology similar to that of an Arabidopsis curly leaf mutant. The occurrence of the ect‐pMADS3 phenotype depended on the presence of pMADS3 intron 2 in the transgenes. Occasionally, sil‐pMADS3 and ect‐pMADS3 phenotypes somatically interconverted. Some T1 progeny inherited their parent's pMADS3 expression pattern, while others switched from sil‐pMADS3 to ect‐pMADS3 and vice versa. Both phenotypes occasionally occurred even after the transgenes were segregated away. RT‐PCR analyses of ectopically expressed pMADS3 transcripts indicated that two pMADS3 alleles were often differently regulated. Furthermore, reciprocal crosses with untransformed Petunia indicated that pMADS3 alleles other than the one ectopically expressed in T0 plants were sometimes expressed ectopically in T1 plants: the paramutation‐like transmission of epigenetic regulation between alleles. We detected in the transformants aberrant transcripts, including sense and antisense pMADS3 intron 2 sequences of heterogeneous molecular sizes, irrespective of the pMADS3 phenotypes. We speculate on possible molecular mechanisms underlying these epigenetic phenomena.
Toc64 is not required for import of proteins into chloroplasts in the mossPhyscomitrella patens
Authors: Hofmann Nancy Rosenbaum , Theg Steven M.
Published: August 2005

Toc64 has been suggested to be part of the chloroplast import machinery inPisum sativum. A role for Toc64 in protein transport has not been established, however. To address this, we generated knockout mutants in the mossPhyscomitrella patensusing the moss's ability to perform homologous recombination with nuclear DNA.Physcomitrella patenscontains two genes that encode Toc64‐like proteins. Both of those proteins appear to be localized in the chloroplast. The double‐mutant plants were lacking Toc64 protein in the chloroplasts but showed no growth phenotype. In addition, these plants accumulated other plastid proteins at wild‐type levels and showed no difference from wild type inin vitroprotein import assays. These plants did have a slightly altered chloroplast shape in some tissues, however. The evidence therefore indicates that Toc64 proteins are not required for import of proteins inPhyscomitrella, but may point to involvement in the determination of plastid shape.
Editing of plastid RNA in Arabidopsis thaliana ecotypes
Authors: Tillich Michael , Funk Helena T. , Schmitz‐Linneweber Christian , Poltnigg Peter , Sabater Bartolomé , Martin Mercedes , Maier Rainer M.
Published: August 2005

Post‐transcriptional maturation of plastid‐encoded mRNAs from land plants includes editing by making cytidine to uridine alterations at highly specific positions; this usually restores codon identities for conserved amino acids that are important for the proper function of the affected proteins. In contrast to the rather constant number of editing sites their location varies greatly, even between closely related taxa. Here, we experimentally determined the specific pattern of editing sites (the editotype) of the plastid genome of Arabidopsis thaliana ecotype Columbia (Col‐0). Based on phylogenetic analyses of plastid open reading frames, we identified 28 editing sites. Two editing events in the genes matK and ndhB seem to have evolved late during the evolution of flowering plants. Strikingly, they are embedded in almost identical sequence elements and seem to be phylogenetically co‐processed. This suggests that the two sites are recognized by the same trans‐factor, which could help to explain the hitherto enigmatic gain of editing sites in evolution. In order to trace variations in editotype at the subspecies level we examined two other A. thaliana accessions, Cape Verde Islands (Cvi‐0) and Wassilewskija (Ws‐2), for the Col‐0 editing sites. Both Cvi‐0 and Ws‐2 possess and process the whole set of editing sites as determined in Col‐0, but the consequences of RNA editing differ at one position between the ecotypes.
Rice NRR, a negative regulator of disease resistance, interacts with Arabidopsis NPR1 and rice NH1
Authors: Chern Mawsheng , Canlas Patrick E. , Fitzgerald Heather A. , Ronald Pamela C.
Published: August 2005

Arabidopsis NPR1/NIM1 is a key regulator of systemic acquired resistance (SAR), which confers lasting broad‐spectrum resistance. Over‐expression of Arabidopsis NPR1 or the NPR1 homolog 1 (NH1) in rice results in enhanced resistance to the pathogen Xanthomonasoryzae pv. oryzae (Xoo), suggesting the presence of a related defense pathway in rice. We investigated this pathway in rice by identifying proteins that interact with NH1. Here we report the isolation and characterization of a rice cDNA encoding a novel protein, named NRR (for negative regulator of resistance). NRR interacts with NPR1 in the NPR1‐interacting domain (NI25) consisting of 25 amino acids. NRR also interacts with NH1; however, NI25 was not sufficient for a strong interaction, indicating a difference between the rice and the Arabidopsis proteins. Silencing of NRR in rice had little effect on resistance to Xoo. When constitutively over‐expressed in rice, NRR affected basal resistance, age‐related resistance and Xa21‐mediated resistance, causing enhanced susceptibility to Xoo. This phenotype was correlated with elevated NRR mRNA and protein levels and increased Xoo growth. Over‐expression of NRR suppressed the induction of defense‐related genes. NRR:GFP (green fluorescent protein) protein was localized to the nucleus, indicating that NRR may act directly to suppress the activation of defense genes. The fact that NRR compromises Xa21‐mediated resistance indicates cross‐talk or overlap between NH1‐ and Xa21‐mediated pathways.
Improved transcriptional activators and their use in mis‐expression traps in Arabidopsis
Authors: Rutherford Stephen , Brandizzi Federica , Townley Helen , Craft Judith , Wang Yibing , Jepson Ian , Martinez Alberto , Moore Ian
Published: August 2005

The synthetic transcription factor LhG4 has been used in numerous mis‐expression studies in plants. We show that the sequence encoding the LhG4 activation domain, derived from Saccharomyces cerevisiae GAL4, contains several cryptic polyadenylation signals in Arabidopsis. The GAL4‐derived sequence was modified according to preferred Arabidopsis codon usage, generating LhG4AtO which was faithfully transcribed in Arabidopsis plants. In protoplasts, LhG4AtO achieved maximum transactivation of the pOp promoter with 10‐fold less input DNA than LhG4. The same methods were used to compare 10 other LhG4 derivatives that carried alternative natural or synthetic activation domains. Lh214 and Lh314, which contain synthetic activation domains comprising trimers of a core acidic activation domain, directed threefold more GUS expression from the pOp promoter with 20‐fold less input DNA than LhG4. In contrast, when expressed from the CaMV 35S promoter in transgenic plants carrying a pOp–GUS reporter, Lh214 and Lh314 yielded transformants with substantially lower GUS activities than other constructs including LhG4AtO and LhG4 which performed similarly. When incorporated into an enhancer‐trapping vector, however, LhG4AtO and Lh314 yielded enhancer traps with approximately twice the frequency of LhG4, suggesting that the modified activation domains offer improved performance when expressed from weaker transcription signals. To increase the number of LhG4 patterns available for mis‐expression studies, we describe a population of enhancer‐trap lines obtained with LhG4AtO in a pOp–GUS background. We show that enhancer‐trap lines can transactivate an unlinked pOp–green fluorescent protein (pOp‐GFP) reporter in the pattern predicted by staining for GUS activity.
Expression of floral MADS‐box genes in basal angiosperms: implications for the evolution of floral regulators
Authors: Kim Sangtae , Koh Jin , Yoo Mi‐Jeong , Kong Hongzhi , Hu Yi , Ma Hong , Soltis Pamela S. , Soltis Douglas E.
Published: August 2005

The ABC model of floral organ identity is based on studies of Arabidopsis and Antirrhinum, both of which are highly derived eudicots. Most of the genes required for the ABC functions in Arabidopsis and Antirrhinum are members of the MADS‐box gene family, and their orthologs are present in all major angiosperm lineages. Although the eudicots comprise 75% of all angiosperms, most of the diversity in arrangement and number of floral parts is actually found among basal angiosperm lineages, for which little is known about the genes that control floral development. To investigate the conservation and divergence of expression patterns of floral MADS‐box genes in basal angiosperms relative to eudicot model systems, we isolated several floral MADS‐box genes and examined their expression patterns in representative species, including Amborella (Amborellaceae), Nuphar (Nymphaeaceae) and Illicium (Austrobaileyales), the successive sister groups to all other extant angiosperms, plus Magnolia and Asimina, members of the large magnoliid clade. Our results from multiple methods (relative‐quantitative RT‐PCR, real‐time PCR and RNA in situ hybridization) revealed that expression patterns of floral MADS‐box genes in basal angiosperms are broader than those of their counterparts in eudicots and monocots. In particular, (i) AP1 homologs are generally expressed in all floral organs and leaves, (ii) AP3/PI homologs are generally expressed in all floral organs and (iii) AG homologs are expressed in stamens and carpels of most basal angiosperms, in agreement with the expectations of the ABC model; however, an AG homolog is also expressed in the tepals of Illicium. The broader range of strong expression of AP3/PI homologs is inferred to be the ancestral pattern for all angiosperms and is also consistent with the gradual morphological intergradations often observed between adjacent floral organs in basal angiosperms.
The transcription factor ATAF2 represses the expression of pathogenesis‐related genes in Arabidopsis
Authors: Delessert Christian , Kazan Kemal , Wilson Iain W. , Straeten Dominique Van Der , Manners John , Dennis Elizabeth S. , Dolferus Rudy
Published: August 2005

ATAF2, a member of the plant‐specific NAC‐domain transcription factor family, is highly induced in leaves at a wound site and is responsive to the wound‐related phytohormones methyl jasmonate and salicylic acid, but not to abscisic acid. Overexpression of ATAF2 leads to an increased biomass and yellowing of the leaves, but there is no obvious phenotype in two independent ATAF2 T‐DNA insertion lines. At the transcriptome level, ATAF2 overexpression resulted in repression of a number of pathogenesis‐related proteins. Conversely, four of these pathogenesis‐related transcripts were increased in both ATAF2 knock‐out lines. ATAF2 overexpressing plants showed a higher susceptibility to the soil‐borne fungal pathogen Fusarium oxysporum. Our results indicate that ATAF2 functions as a repressor of pathogenesis‐related proteins in Arabidopsis.
Tobacco plants respond to the constitutive expression of the tospovirus movement protein NSM with a heat‐reversible sealing of plasmodesmata that impairs development
Authors: Rinne Päivi L.H. , Boogaard Riki van den , Mensink Manon G.J. , Kopperud Cor , Kormelink Richard , Goldbach Rob , Schoot Chris van der
Published: August 2005

Viral infection often results in typical symptoms, the biological background of which has remained elusive. We show that constitutive expression of the NSM viral movement protein (MP) of tomato spotted wilt virus in Nicotiana tabacum is sufficient to induce severe, infection‐like symptoms, including pronounced deficiencies in root and shoot development. Leaves failed to expand and were arranged in a rosette due to the absence of internode elongation. Following the sink–source transition they accumulated excessive amounts of starch and developed fusing chlorotic patches in the mesophyll, resembling virus‐induced chlorotic lesions. Eventually, the leaves became entirely white and brittle. With a combination of techniques, including photosystem II quantum‐yield measurements, iontophoresis of symplasmic tracers, bombardment with pPVX.GFP and double immunolabelling it was shown that these symptoms correlated with the obstruction of NSM‐targeted mesophyll plasmodesmata (Pd) in source tissues by depositions of 1,3‐β‐D‐glucan (GLU) or callose. Temperature‐shift treatments (TST; 22→32°C), known to abolish chlorotic local lesions, also abolished the chlorotic ‘superlesions’ of transgenic plants and rescued plant development, by restoring the transport capacity of Pd through the action of 1,3‐β‐D‐glucanase (GLU‐h) or callase. Return of these elongated, TST‐recovered plants to 22°C reintroduced superlesions and arrested shoot elongation, resulting in the formation of a rosette of clustered leaves at the shoot tip. Collectively, this indicates that the symptoms of NSM plants are self‐inflicted and due to a basal defence response that counteracts prolonged interference of the MP with Pd functioning. This type of defence may also play a role in the formation of symptoms during viral infection.
The stylar 120 kDa glycoprotein is required for S‐specific pollen rejection in Nicotiana
Authors: Nathan Hancock C. , Kent Lia , McClure Bruce A.
Published: August 2005

S‐RNase participates in at least three mechanisms of pollen rejection. It functions in S‐specific pollen rejection (self‐incompatibility) and in at least two distinct interspecific mechanisms of pollen rejection in Nicotiana. S‐specific pollen rejection and rejection of pollen from Nicotiana plumbaginifolia also require additional stylar proteins. Transmitting‐tract‐specific (TTS) protein, 120 kDa glycoprotein (120K) and pistil extensin‐like protein III (PELP III) are stylar glycoproteins that bind S‐RNase in vitro and are also known to interact with pollen. Here we tested whether these glycoproteins have a direct role in pollen rejection. 120K shows the most polymorphism in size between Nicotiana species. Larger 120K‐like proteins are often correlated with S‐specific pollen rejection. Sequencing results suggest that the polymorphism primarily reflects differences in glycosylation, although indels also occur in the predicted polypeptides. Using RNA interference (RNAi), we suppressed expression of 120K to determine if it is required for S‐specific pollen rejection. Transgenic SC N. plumbaginifolia × SI Nicotiana alata (S105S105 or SC10SC10) hybrids with no detectable 120K were unable to perform S‐specific pollen rejection. Thus, 120K has a direct role in S‐specific pollen rejection. However, suppression of 120K had no effect on rejection of N. plumbaginifolia pollen. In contrast, suppression of HT‐B, a factor previously implicated in S‐specific pollen rejection, disrupts rejection of N. plumbaginifolia pollen. Thus, S‐specific pollen rejection and rejection of N. plumbaginifolia pollen are mechanistically distinct, because they require different non‐S‐RNase factors.
Overexpression of COL9, a CONSTANS‐LIKE gene, delays flowering by reducing expression of CO and FT in Arabidopsis thaliana
Authors: Cheng Xiao‐Fei , Wang Zeng‐Yu
Published: August 2005

CONSTANS (CO) is an important floral regulator in the photoperiod pathway, integrating the circadian clock and light signal into a control for flowering time. It is known that CO promotes flowering in Arabidopsis under long‐day conditions. CONSTANS‐LIKE 9 (COL9) is a member of the CONSTANS‐LIKE gene family, encoding a nuclear protein. The expression of COL9 is regulated by the circadian clock in the photoperiod pathway and is detected in various organs. Unexpectedly, overexpression of COL9 in transgenic Arabidopsis resulted in delayed flowering, while co‐suppression lines and a transferred DNA (T‐DNA) knockout line showed earlier flowering under long‐day conditions. Overexpression of COL9 did not enhance the late‐flowering phenotype in a co mutant background. Double overexpressors produced by overexpression of CO in COL9 transgenic lines showed an early flowering phenotype similar to single CO overexpressors. The pattern of oscillation of a number of circadian‐associated genes remained unchanged in the COL9 transgenic lines. Compared with wild‐type plants, the abundance of CO and FLOWERING LOCUS T (FT) mRNA was reduced in the COL9 overexpression lines. Our results indicate that COL9 is involved in regulation of flowering time by repressing the expression of CO, concomitantly reducing the expression of FT and delaying floral transition.
Biotechnological improvement of cotton fibre maturity
Authors: Haigler Candace H. , Zhang Deshui , Wilkerson Curtis G.
Published: August 2005

This mini‐review focuses on the prospects and tools for controlling cotton fibre secondary wall thickness. Cotton fibre secondary walls are composed of almost 100% cellulose, and are responsible for fibre maturity and a large component of fibre yield. Improved fibre yield and maturity would result from the ability to control secondary wall cellulose deposition quantitatively, including making the process less sensitive to environmental stress. Both genetic engineering and marker‐assisted breeding are possible avenues for effecting such improvements, but first key genes that participate in the regulation and control of secondary wall cellulose biogenesis must be identified. Recent advances towards understanding and manipulating cotton fibre secondary wall deposition that are discussed here include: (i) experimental approaches to identify metabolic participants in cellulose biogenesis; (ii) isolation and characterization of promoters to drive foreign gene expression preferentially during secondary wall deposition; and (iii) a novel set of cDNA sequences representing genes that are differentially expressed during cotton fibre secondary wall deposition compared with primary wall deposition.
Identification, accumulation, and functional prediction of novel tomato transcripts systemically upregulated after fire damage
Authors: Coker Jeffrey Scott , Vian Alain , Davies Eric
Published: August 2005

Despite the major impacts of fire on plants, responses to fire damage have not been closely studied on the level of gene expression. Here, we present analyses of novel transcripts from tomato (Lycopersicon esculentum cv. Heinz), which are systemically upregulated in leaves after a distant leaf is wounded by flame. Nine cDNA fragments were isolated from a subtractive cDNA library of leaf tissue 1 h after flaming. Using data mining and polymerase chain reaction (PCR), full‐length open‐reading frames were predicted, amplified, and then sequenced. Real‐time (RT)‐PCR using leaf RNA after flaming confirmed the systemic accumulation of 4 and 7 transcripts within 30 and 60 min, respectively, before returning to basal levels within 3 h. During this same time course, proteinase inhibitor I levels gradually increased over 30‐fold in 6 h. Expression analyses also showed that eight of the transcripts are present in unwounded leaf, stem, and root tissues. The predicted proteins include an acyl carrier, adenylyl sulfate reductase, PS II oxygen‐evolving complex protein 3, anion : sodium symporter, chloroplast‐specific ribosomal protein, a histidine triad family protein, and an unknown wound/stress‐related protein. Homologs of several of these proteins have been associated with other types of wound and stress responses. It appears that, within an hour after being damaged by fire, plants systemically upregulate a variety of genes involved with basic cell metabolism and upkeep, in addition to classic defense genes such as proteinase inhibitors.
Aroma production from cut sweet pea flowers (Lathyrus odoratus): the role of ethylene
Authors: Sexton Roy , Stopford Andrew P. , Moodie William T. , Porter Alexander E. A.
Published: August 2005

The major components of the scent of cut sweet pea flowers (Lathyrus odoratus L. cv Royal Wedding) are (E) and (Z)‐ocimene, linalool, nerol, geraniol and phenylacetaldehyde. The aroma is almost exclusively produced by the standard and wing petals, with very little emanating from the keel petals and other floral structures. Only traces of these volatiles were detected in the liquid excreted by glandular trichomes on the surface of the scented petals. Once flowers are cut for display they produce increasing amounts of ethylene which induces wilting after 48 h and petal abscission 24 h later. The rate of linalool and ocimene emission declines over the first 48 h to approximately 10% of that directly after harvest. Ethylene production is not saturating during the first 24 h of vase life and exogenous ethylene further accelerates the senescence processes and loss of fragrance. Addition of the ethylene antagonists 1‐methylcyclopropene (1‐MCP) and silver thiosulphate (STS) delayed wilting and abscission for several days and similarly inhibits the decline in terpenoid emission.
Characterization of new maize chloroplastic copper/zinc superoxide dismutase isoforms by high resolution native two‐dimensional polyacrylamide gel electrophoresis. Identification of chilling responsive chloroplastic superoxide dismutase isoforms
Authors: Mauro Sergio , Van Eycken Françoise , Challou Najib , Lucas Patrick , L'Oiseau Michèle
Published: August 2005

The response of superoxide dismutases (SOD, EC1.15.1.1) to chilling‐induced oxidative stress in differentially sensitive maize genotypes (Zea mays L) was examined. A native 2D‐PAGE system that resolves the maize leaf SOD isoforms has been developed. The chloroplastic SOD activity was resolved into four Cu/Zn SOD isoforms designated SOD1a→d with pI values of 3.9, 4.0, 4.5 and 5.6, respectively. These SODs are located in the stroma and display a higher resistance to hydrogen peroxide inactivation than the cytosol Cu/ZnSODs. They operate as 32 kDa homodimers and have an AT motif at the NH2‐terminal, which characterizes the chloroplastic SODs of most species. A light chilling treatment resulted in a rapid increase in the activity of SOD1a and SOD1b. Because this increase was observed in the presence of the protein synthesis inhibitor cycloheximide, it is suggested that short‐term regulation of chloroplastic SODs occurs at a post‐translational level.