bluuebunny/crossref_metadata_2025 huggingface dataset:
ULTRAFILTRATION THROUGH COLLODION MEMBRANES
Authors: Grollman Arthur
Published: May 2004

It is obvious that the factors considered in this paper render data obtained by ultrafiltration open to criticism unless they are checked by other methods and precautions are taken for the elimination of the vitiating effects which have been described.

As regards the mechanism of ultrafiltration, the view of a sieve-like action as most experimental evidence indicates, is adequate, if all the factors are considered which might modify the effective pore size. The behaviors of collodion membranes which seem contrary to a mechanism of ultrafiltration based on the existence of a system of pores, can be explained on the basis of a variable layer of adsorbed fluid on the walls of the pores. It is, therefore, unsound to make any deductions about living tissues from the demonstration of changes produced in the behavior of collodion membranes. Thus, the increase in the rate of filtration of water through collodion by diuretics (29) or the change of permeability due to the presence of surface-active materials, gives us no information about their action in the living organism. The effect of these substances on a sieve-like membrane of the type of collodion would not necessarily bear any analogy to that exerted on the emulsion type of membrane of living cells. The mechanisms of the reactions necessary to produce the same effects in such widely differing systems may be entirely unrelated.
The Determinants of Governance: A Cross‐Country Analysis
Authors: Al‐Marhubi Fahim
Published: May 2004

Drawing on insights from economic, political, and cultural theories of governance, this article investigates the determinants of governance for a large sample of countries, both developed and developing. The results indicate that countries with a history of Western European influence and with British common law origins have better governance. In addition to these exogenous and historically predetermined variables, economic factors such as openness to trade, resource‐intensity in exports, and levels of economic development have a significant impact on governance. (JEL D73, H11, K42)
Serum Ceruloplasmin and Ferroxidase Activity Are Not Decreased in Hepatic Failure Related to Alcoholic Cirrhosis: Clinical and Pathophysiological Implications
Authors: Le Lan Caroline , Ropert Martine , Lainé Fabrice , Medevielle Muriel , Jard Christine , Pouchard Michel , Le Treut André , Moirand Romain , Loréal Olivier , Brissot Pierre
Published: May 2004

Abstract: Background: A decrease in serum ceruloplasmin (Cp), a protein involved in iron metabolism through its ferroxidase activity, is classically claimed to be observed in severe hepatic failure of non‐wilsonian chronic liver disease and therefore to be a confounding factor for the diagnosis of Wilson's disease. Moreover, a simultaneous decrease in ferroxidase activity could be hypothesized as playing a role in the development of the hepatic siderosis frequently observed in advanced chronic liver diseases. The aim of this study was to test the validity of these two statements.

Methods: This study investigated Cp, determined by immunonephelometry, and its ferroxidase 1 activity determined by Erel's method in 33 male patients with severe alcoholic cirrhosis compared with 66 healthy male volunteers, selected on strict criteria. Each patient was age‐matched with two controls. Nonparametric tests were used for statistical analysis.

Results: The mean values of Cp were significantly higher in cirrhotic patients as compared with control subjects. A significant elevation of Cp was also observed in the subgroup of 11 cirrhotic patients who had normal serum C‐reactive protein levels. The mean values of ferroxidase 1 activity were similar to those obtained in control subjects.

Conclusions: Low serum Cp should not be expected in severe hepatic cirrhosis of non‐wilsonian origin. Hepatic siderosis in advanced chronic liver disease is likely to be unrelated to decreased ferroxidase activity.
Prenatal Maternal Alcohol Consumption and Hospitalization With Asthma in Childhood: A Population‐Based Follow‐Up Study
Authors: Yuan Wei , Sørensen Henrik Toft , Basso Olga , Olsen Jørn
Published: May 2004

Abstract: Background: Asthma may have a prenatal origin. We examined whether maternal alcohol consumption during pregnancy increases the risk of hospitalization with asthma in children.

Methods: We conducted a follow‐up study on 10,440 singletons born at approximately 36 weeks of gestation or later to mothers attending midwife centers between April 1984 and April 1987 in Denmark. The mothers completed a questionnaire regarding lifestyle and socioeconomic factors, including alcohol consumption. The children were followed up through the Danish Hospital Discharge Registry. We determined the first hospitalization with a discharge diagnosis of asthma as recorded in the Danish Hospital Discharge Registry.

Results: Most pregnant women (81.5%) drank at least some alcohol during pregnancy, but only a few (2.1%) consumed 120 g or more per week. In total, 307 children were hospitalized at least once with a discharge diagnosis of asthma during follow‐up (the cumulative incidence risk was 3.5% from birth to 12 years of age or the end of follow‐up). After adjusting for maternal socioeconomic factors, dietary components, and other lifestyle factors, children whose mothers drank alcohol during pregnancy did not have an increased risk of hospitalization with asthma compared with the children of mothers who reported no alcohol consumption during pregnancy (adjusted incidence rate ratio, 0.95; 95% confidence interval, 0.70–1.29). Further analyses showed no association with the dose and type of alcohol or with binge drinking.

Conclusions: The study provides no support for a causal link between maternal alcohol intake during pregnancy and asthma in childhood.
Effect of Dealcoholized Beer (Bitburger Drive®) Consumption on Hemostasis in Humans
Authors: Bassus S. , Mahnel R. , Scholz T. , Wegert W. , Westrup D. , Kirchmaier C. M.
Published: May 2004

Abstract: Background: The beneficial effect of moderate alcohol consumption in lowering the risk of cardiovascular disease has been shown in several epidemiologic studies. Such studies have also shown, however, that the protective effect of alcoholic beverages like wine and beer is not only due to the ethanol content but also to the presence of nonalcoholic constituents. The positive effect of alcoholic beverages has been attributed to changes in lipoprotein metabolism, but there is substantial evidence that effects on hemostasis play an important role. Whether the effects of alcoholic beverages on hemostasis are due exclusively to ethanol or are due, in part, to nonalcoholic components, is still under debate.

Methods: We have examined the hemostatic effects of 3 liters of beer, dealcoholized beer, and ethanol/water (v/v 4%), consumed over a period of 3 hr, in 12 young healthy volunteers. Platelet parameters CD62, PAC‐1, and monocyte platelet aggregates were analyzed using flow cytometric measurements. The activity of factor VII was determined with a prothrombin time (PT) assay and plasminogen activator inhibitor activity using a chromogenic substrate. Thrombin generation was determined according to the method of Hemker.

Results: All three fluids administered, dealcoholized beer, beer, and ethanol, reduced the expression of activated fibrinogen receptor, the platelet activation marker CD62, and the formation of monocyte‐platelet‐aggregate. In addition, dealcoholized beer also showed significant inhibitory effects on thrombin generation, whereas beer and ethanol showed procoagulatory effects.

Conclusions: This study has shown that the acute consumption of dealcoholized beer inhibits thrombogenic activity in young adults. This action could have a beneficial effect on the development of coronary artery disease. Thus, the consumption of dealcoholized beer could provide cardiovascular benefit without the negative effects of alcohol.
Alcohol Acutely Down‐Regulates Urea Synthesis in Normal Men
Authors: Aagaard Niels Kristian , Thøgersen Thøger , Grøfte Thorbjørn , Greisen Jacob , Vilstrup Hendrik
Published: May 2004

Abstract: Background: Human nitrogen balance studies suggest that alcohol up‐regulates urea synthesis and promotes nitrogen catabolism, whereas animal studies conversely indicate that alcohol down‐regulates urea synthesis, possibly via a redox effect. This study aimed to investigate the acute effects of alcohol exposure at a plasma concentration of about 10 mmol/liter on urea synthesis in healthy volunteers and to investigate whether methylene blue alleviates the effect of alcohol.

Methods: Eleven males were studied three times in a randomized sequence crossover design. They received either alanine infusion to control the rate of urea synthesis (control), alanine + alcohol, or alanine + alcohol + methylene blue. The substrate independent regulation of urea synthesis was studied by means of the functional hepatic nitrogen clearance, that is, the slope of the linear relation between blood amino nitrogen concentrations and rates of urea synthesis.

Results: Alcohol reduced functional hepatic nitrogen clearance to 37% and 51% during alcohol and alcohol + methylene blue infusion, respectively (p= 0.007). Accordingly, whole body nitrogen retention was higher during alcohol infusion. Glucagon, which up‐regulates urea synthesis, increased during alcohol infusion. There was no change in insulin. Blood glucose was slightly lower at the end of the experiment when alcohol was infused.

Conclusion: Low‐dose infusion of alcohol acutely down‐regulated urea synthesis in healthy volunteers, transiently favoring nitrogen preservation. The effect seemed not to depend on hormonal changes. It remains to be explored how the present results can be reconciled with the reported nitrogen wasting of chronic alcoholics.
Effect of Moderate Alcohol Consumption on Plasma Dehydroepiandrosterone Sulfate, Testosterone, and Estradiol Levels in Middle‐Aged Men and Postmenopausal Women: A Diet‐Controlled Intervention Study
Authors: Sierksma Aafje , Sarkola Taisto , Eriksson C. J. Peter , van der Gaag Martijn S. , Grobbee Diederick E. , Hendriks Henk F. J.
Published: May 2004

Abstract: Background: Moderate alcohol consumption is inversely associated with cardiovascular diseases. Changes in hormone levels might in part help explain the positive health effect. This study was performed to examine the effect of moderate alcohol consumption on plasma dehydroepiandrosterone sulfate (DHEAS), testosterone, and estradiol levels.

Methods: In a randomized, diet‐controlled, crossover study, 10 middle‐aged men and 9 postmenopausal women, all apparently healthy, nonsmoking, and moderate alcohol drinkers, consumed beer or no‐alcohol beer with dinner during two successive periods of 3 weeks. During the beer period, alcohol intake equaled 40 and 30 g per day for men and women, respectively. The total diet was supplied and had essentially the same composition during these 6 weeks. Before each treatment there was a 1 week washout period, in which the subjects were not allowed to drink alcoholic beverages. At the end of each of the two experimental periods, fasting blood samples were collected in the morning.

Results: Moderate alcohol consumption increased plasma DHEAS level by 16.5% (95% confidence interval, 8.0–24.9), with similar changes for men and women. Plasma testosterone level decreased in men by 6.8% (95% confidence interval, −1.0–−12.5), but no effect was found in women. Plasma estradiol level was not affected. Serum high‐density lipoprotein cholesterol level increased by 11.7% (95% confidence interval, 7.3–16.0), with similar changes for men and women. The overall alcohol‐induced relative changes in DHEAS, testosterone, and estradiol correlated positively with the relative increase in high‐density lipoprotein cholesterol (adjusted for the relative change in body weight); however, findings were only borderline significant for DHEAS and estradiol (r= 0.44, p= 0.08; r= 0.32, p= 0.21; and r= 0.46, p= 0.06, respectively).

Conclusions: A protective effect of moderate alcohol consumption for cardiovascular disease risk may in part be explained by increased plasma DHEAS level.
Acute Alcohol Consumption Inhibits Accessory Cell Function of Monocytes and Dendritic Cells
Authors: Szabo Gyongyi , Catalano Donna , White Bernadette , Mandrekar Pranoti
Published: May 2004

Abstract: Background: Alcohol affects both innate and acquired immune responses. Chronic alcoholics have reduced delayed‐type hypersensitivity response and increased susceptibility to infections. In contrast, recent studies suggest that acute, moderate alcohol consumption has protective effects on mortality. Monocytes and dendritic cells (DC) play a central role in coordination of innate and adaptive immune responses and are pivotal in activation of T lymphocytes in an antigen‐specific manner. In this study, we investigated the effects of acute, moderate alcohol consumption on antigen presenting cell function of blood monocytes and monocyte‐derived myeloid dendritic cells.

Methods: Accessory cell function of human blood monocytes was tested before and after acute alcohol intake (2 ml vodka/kg body weight) by measuring T cell activation with alloantigen (mixed lymphocyte reaction, MLR), superantigen (staphylococcal enterotoxin B) and recall antigen (tetanus toxoid). Myeloid DCs were generated in vitro from monocytes obtained from these individuals using IL‐4 and GM‐CSF and their allostimulatory function was tested in an MLR.

Results: We found significantly reduced T cell proliferation in the presence of monocytes obtained 2 or 18 hr after alcohol consumption whether alloantigen, superantigen, or recall antigen was the stimuli (p < 0.01). The reduced T cell proliferation was due to the effects of acute alcohol on monocytes rather than on T cells as we found decreased proliferation only in the presence of alcohol‐exposed accessory cells but not when T cells were exposed to alcohol. In addition, monocyte‐derived dendritic cells showed significantly reduced allostimulatory capacity after alcohol consumption (p < 0.005).

Conclusion: Acute alcohol consumption inhibits accessory cell function of both monocytes and myeloid dendritic cells. Impaired function of these key antigen‐presenting cells may contribute to reduced adaptive immune responses and increased susceptibility to infections when acute alcohol intake coincides with exposure to pathogens.
Overexpression of Selenocysteine Methyltransferase in Arabidopsis and Indian Mustard Increases Selenium Tolerance and Accumulation
Authors: LeDuc Danika L. , Tarun Alice S. , Montes-Bayon Maria , Meija Juris , Malit Michele F. , Wu Carol P. , AbdelSamie Manal , Chiang Chih-Yuan , Tagmount Abderrhamane , deSouza Mark , Neuhierl Bernhard , Böck August , Caruso Joseph , Terry Norman
Published: May 2004

A major goal of phytoremediation is to transform fast-growing plants with genes from plant species that hyperaccumulate toxic trace elements. We overexpressed the gene encoding selenocysteine methyltransferase (SMT) from the selenium (Se) hyperaccumulator Astragalus bisulcatus in Arabidopsis and Indian mustard (Brassica juncea). SMT detoxifies selenocysteine by methylating it to methylselenocysteine, a nonprotein amino acid, thereby diminishing the toxic misincorporation of Se into protein. Our Indian mustard transgenic plants accumulated more Se in the form of methylselenocysteine than the wild type. SMT transgenic seedlings tolerated Se, particularly selenite, significantly better than the wild type, producing 3- to 7-fold greater biomass and 3-fold longer root lengths. Moreover, SMT plants had significantly increased Se accumulation and volatilization. This is the first study, to our knowledge, in which a fast-growing plant was genetically engineered to overexpress a gene from a hyperaccumulator in order to increase phytoremediation potential.
A Comparison of Rice Chloroplast Genomes
Authors: Tang Jiabin , Xia Hong'ai , Cao Mengliang , Zhang Xiuqing , Zeng Wanyong , Hu Songnian , Tong Wei , Wang Jun , Wang Jian , Yu Jun , Yang Huanming , Zhu Lihuang
Published: May 2004

Using high quality sequence reads extracted from our whole genome shotgun repository, we assembled two chloroplast genome sequences from two rice (Oryza sativa) varieties, one from 93-11 (a typical indica variety) and the other from PA64S (an indica-like variety with maternal origin of japonica), which are both parental varieties of the super-hybrid rice, LYP9. Based on the patterns of high sequence coverage, we partitioned chloroplast sequence variations into two classes, intravarietal and intersubspecific polymorphisms. Intravarietal polymorphisms refer to variations within 93-11 or PA64S. Intersubspecific polymorphisms were identified by comparing the major genotypes of the two subspecies represented by 93-11 and PA64S, respectively. Some of the minor genotypes occurring as intravarietal polymorphisms in one variety existed as major genotypes in the other subspecific variety, thus giving rise to intersubspecific polymorphisms. In our study, we found that the intersubspecific variations of 93-11 (indica) and PA64S (japonica) chloroplast genomes consisted of 72 single nucleotide polymorphisms and 27 insertions or deletions. The intersubspecific polymorphism rates between 93-11 and PA64S were 0.05% for single nucleotide polymorphisms and 0.02% for insertions or deletions, nearly 8 and 10 times lower than their respective nuclear genomes. Based on the total number of nucleotide substitutions between the two chloroplast genomes, we dated the divergence of indica and japonica chloroplast genomes as occurring approximately 86,000 to 200,000 years ago.
Coordinate Expression and Independent Subcellular Targeting of Multiple Proteins from a Single Transgene
Authors: El Amrani Abdelhak , Barakate Abdellah , Askari Barak M. , Li Xuejun , Roberts Alison G. , Ryan Martin D. , Halpin Claire
Published: May 2004

A variety of conventional methods allow the expression of multiple foreign proteins in plants by transgene stacking or pyramiding. However, most of these approaches have significant drawbacks. We describe a novel alternative, using a single transgene to coordinate expression of multiple proteins that are encoded as a polyprotein capable of dissociating into component proteins on translation. We demonstrate that this polyprotein system is compatible with the need to target proteins to a variety of subcellular locations, either cotranslationally or posttranslationally. It can also be used to coordinate the expression of selectable marker genes and effect genes or to link genes that are difficult to assay to reporter genes that are easily monitored. The unique features of this polyprotein system are based on the novel activity of the 2A peptide of Foot-and-mouth disease virus (FMDV) that acts cotranslationally to effect a dissociation of the polyprotein while allowing translation to continue. This polyprotein system has many applications both as a research tool and for metabolic engineering and protein factory applications of plant biotechnology.
Optospectroscopic Detection of Primary Reactions Associated with the Graviperception of Phycomyces. Effects of Micro- and Hypergravity
Authors: Schmidt Werner , Galland Paul
Published: May 2004

The graviperception of sporangiophores of the fungus Phycomyces blakesleeanus involves gravity-induced absorbance changes (GIACs) that represent primary responses of gravitropism (Schmidt and Galland, 2000). GIACs (ΔA460–665) of sporangiophores were measured in vivo with a micro-dual wavelength spectrometer at 460 and 665 nm. Sporangiophores that were placed horizontally displayed an instant increase of the GIACs while the return to the vertical position elicited an instant decrease. The GIACs are specific for graviperception, because they were absent in a gravitropism mutant with a defective madJ gene. During parabola flights hypergravity (1.8g) elicited a decrease of the GIACs, while microgravity (0 ± 3 × 10−2  g) elicited an instant increase. Hypergravity that was generated in a centrifuge (1.5–6.5g) elicited also a decrease of the GIACs that saturated at about 5g. The GIACs have a latency of about 20 ms or shorter and are thus the fastest graviresponses ever measured for fungi, protists, and plants. The threshold for eliciting the GIACs is near 3 × 10−2  g, which coincides numerically with the threshold for gravitropic bending. In contrast to gravitropic bending, which requires long-term stimulation, GIACs can be elicited by stimuli as short as 20 to 100 ms, leading to an extremely low threshold dose (acceleration × time) of about 3 × 10−3  g s, a value, which is four orders of magnitude below the ones described for other organisms and which makes the GIACs of Phycomyces blakesleeanus the most sensitive gravi-response in literature.
Quantitative Trait Loci Associated with Drought Tolerance at Reproductive Stage in Rice
Authors: Lanceras Jonaliza C. , Pantuwan Grienggrai , Jongdee Boonrat , Toojinda Theerayut
Published: May 2004

Drought is a major constraint to rice (Oryza sativa) yield and its stability in rainfed and poorly irrigated environments. Identifying genomic regions influencing the response of yield and its components to water deficits will aid in our understanding of the genetics of drought tolerance and development of more drought tolerant cultivars. Quantitative trait loci (QTL) for grain yield and its components and other agronomic traits were identified using a subset of 154 doubled haploid lines derived from a cross between two rice cultivars, CT9993-510 to 1-M and IR62266-42 to 6-2. Drought stress treatments were managed by use of a line source sprinkler irrigation system, which provided a linearly decreasing level of irrigation coinciding with the sensitive reproductive growth stages. The research was conducted at the Ubon Rice Research Center, Ubon, Thailand. A total of 77 QTL were identified for grain yield and its components under varying levels of water stress. Out of the total of 77 QTL, the number of QTL per trait were: 7-grain yield (GY); 8-biological yield (BY); 6-harvest index (HI); 5-d to flowering after initiation of irrigation gradient (DFAIG); 10-total spikelet number (TSN); 7-percent spikelet sterility (PSS); 23-panicle number (PN); and 11-plant height (PH). The phenotypic variation explained by individual QTL ranged from 7.5% to 55.7%. Under well-watered conditions, we observed a high genetic association for BY, HI, DFAIG, PSS, TSN, PH, and GY. However, only BY and HI were found to be significantly associated with GY under drought treatments. QTL flanked by markers RG104 to RM231, EMP2_2 to RM127, and G2132 to RZ598 on chromosomes 3, 4, and 8 were associated with GY, HI, DFAIG, BY, PSS, and PN under drought treatments. The aggregate effects of these QTL on chromosomes 3, 4, and 8 resulted in higher grain yield. These QTL will be useful for rainfed rice improvement, and will also contribute to our understanding of the genetic control of GY under drought conditions at the sensitive reproductive stage. Close linkage or pleiotropy may be responsible for the coincidence of QTL detected in this experiment. Digenic interactions between QTL main effects for GY, BY, HI, and PSS were observed under irrigation treatments. Most (but not all) DH lines have the same response in measure of productivity when the intensity of water deficit was increased, but no QTL by irrigation treatment interaction was detected. The identification of genomic regions associated with GY and its components under drought stress will be useful for marker-based approaches to improve GY and its stability for farmers in drought-prone rice environments.
Developmental Physiology of Cluster-Root Carboxylate Synthesis and Exudation in Harsh Hakea. Expression of Phosphoenolpyruvate Carboxylase and the Alternative Oxidase
Authors: Shane Michael W. , Cramer Michael D. , Funayama-Noguchi Sachiko , Cawthray Gregory R. , Millar A. Harvey , Day David A. , Lambers Hans
Published: May 2004

Harsh hakea (Hakea prostrata R.Br.) is a member of the Proteaceae family, which is highly represented on the extremely nutrient-impoverished soils in southwest Australia. When phosphorus is limiting, harsh hakea develops proteoid or cluster roots that release carboxylates that mobilize sparingly soluble phosphate in the rhizosphere. To investigate the physiology underlying the synthesis and exudation of carboxylates from cluster roots in Proteaceae, we measured O2 consumption, CO2 release, internal carboxylate concentrations and carboxylate exudation, and the abundance of the enzymes phosphoenolpyruvate carboxylase and alternative oxidase (AOX) over a 3-week time course of cluster-root development. Peak rates of citrate and malate exudation were observed from 12- to 13-d-old cluster roots, preceded by a reduction in cluster-root total protein levels and a reduced rate of O2 consumption. In harsh hakea, phosphoenolpyruvate carboxylase expression was relatively constant in cluster roots, regardless of developmental stage. During cluster-root maturation, however, the expression of AOX protein increased prior to the time when citrate and malate exudation peaked. This increase in AOX protein levels is presumably needed to allow a greater flow of electrons through the mitochondrial electron transport chain in the absence of rapid ATP turnover. Citrate and isocitrate synthesis and accumulation contributed in a major way to the subsequent burst of citrate and malate exudation. Phosphorus accumulated by harsh hakea cluster roots was remobilized during senescence as part of their efficient P cycling strategy for growth on nutrient impoverished soils.
Two New Alleles of the abscisic aldehyde oxidase 3 Gene Reveal Its Role in Abscisic Acid Biosynthesis in Seeds
Authors: González-Guzmán Miguel , Abia David , Salinas Julio , Serrano Ramón , Rodríguez Pedro L.
Published: May 2004

The abscisic aldehyde oxidase 3 (AAO3) gene product of Arabidopsis catalyzes the final step in abscisic acid (ABA) biosynthesis. An aao3-1 mutant in a Landsberg erecta genetic background exhibited a wilty phenotype in rosette leaves, whereas seed dormancy was not affected (Seo et al., 2000a). Therefore, it was speculated that a different aldehyde oxidase would be the major contributor to ABA biosynthesis in seeds (Seo et al., 2000a). Through a screening based on germination under high-salt concentration, we isolated two mutants in a Columbia genetic background, initially named sre2-1 and sre2-2 (for salt resistant). Complementation tests with different ABA-deficient mutants indicated that sre2-1 and sre2-2 mutants were allelic to aao3-1, and therefore they were renamed as aao3-2 and aao3-3, respectively. Indeed, molecular characterization of the aao3-2 mutant revealed a T-DNA insertional mutation that abolished the transcription of AAO3 gene, while sequence analysis of AAO3 in aao3-3 mutant revealed a deletion of three nucleotides and several missense mutations. Physiological characterization of aao3-2 and aao3-3 mutants revealed a wilty phenotype and osmotolerance in germination assays. In contrast to aao3-1, both aao3-2 and aao3-3 mutants showed a reduced dormancy. Accordingly, ABA levels were reduced in dry seeds and rosette leaves of both aao3-2 and aao3-3. Taken together, these results indicate that AAO3 gene product plays a major role in seed ABA biosynthesis.
Heterogeneous Pollen in Chlorophytum comosum, a Species with a Unique Mode of Plastid Inheritance Intermediate between the Maternal and Biparental Modes
Authors: Liu Yang , Zhang Quan , Hu Yufei , Sodmergen
Published: May 2004

The majority of angiosperms display maternal plastid inheritance. The cytological mechanisms of this mode of inheritance have been well studied, but little is known about its genetic relationship to biparental inheritance. The angiosperm Chlorophytum comosum is unusual in that different pollen grains show traits of different modes of plastid inheritance. About 50% of these pollen grains exhibit the potential for biparental plastid inheritance, whereas the rest exhibit maternal plastid inheritance. There is no morphological difference between these two types of pollen. Pollen grains from different individuals of C. comosum all exhibited this variability. Closer examination revealed that plastid polarization occurs, with plastids being excluded from the generative cell during the first pollen mitosis. However, the exclusion is incomplete in 50% of the pollen grains, and the few plastids distributed to the generative cells divide actively after mitosis. Immunoelectron microscopy using an anti-DNA antibody demonstrated that the plastids contain a large amount of DNA. As there is a considerable discrepancy between the exclusion and duplication of plastids, resulting in plastids with opposite fates occurring simultaneously in C. comosum, we propose that the species is a transitional type with a mode of plastid inheritance that is genetically intermediate between the maternal and biparental modes.
Analysis of Natural Allelic Variation of Arabidopsis Seed Germination and Seed Longevity Traits between the Accessions Landsberg erecta and Shakdara, Using a New Recombinant Inbred Line Population
Authors: Clerkx Emile J.M. , El-Lithy Mohamed E. , Vierling Elizabeth , Ruys Gerda J. , Blankestijn-De Vries Hetty , Groot Steven P.C. , Vreugdenhil Dick , Koornneef Maarten
Published: May 2004

Quantitative trait loci (QTL) mapping was used to identify loci controlling various aspects of seed longevity during storage and germination. Similar locations for QTLs controlling different traits might be an indication for a common genetic control of such traits. For this analysis we used a new recombinant inbred line population derived from a cross between the accessions Landsberg erecta (Ler) and Shakdara (Sha). A set of 114 F9 recombinant inbred lines was genotyped with 65 polymerase chain reaction-based markers and the phenotypic marker erecta. The traits analyzed were dormancy, speed of germination, seed sugar content, seed germination after a controlled deterioration test, hydrogen peroxide (H2O2) treatment, and on abscisic acid. Furthermore, the effects of heat stress, salt (NaCl) stress, osmotic (mannitol) stress, and natural aging were analyzed. For all traits one or more QTLs were identified, with some QTLs for different traits colocating. The relevance of colocation for mechanisms underlying the various traits is discussed.
Quantitative Trait Locus Analysis of Growth-Related Traits in a New Arabidopsis Recombinant Inbred Population
Authors: El-Lithy Mohamed E. , Clerkx Emile J.M. , Ruys Gerda J. , Koornneef Maarten , Vreugdenhil Dick
Published: May 2004

Arabidopsis natural variation was used to analyze the genetics of plant growth rate. Screening of 22 accessions revealed a large variation for seed weight, plant dry weight and relative growth rate but not for water content. A positive correlation was observed between seed weight and plant area 10 d after planting, suggesting that seed weight affects plant growth during early phases of development. During later stages of plant growth this correlation was not significant, indicating that other factors determine growth rate during this phase. Quantitative trait locus (QTL) analysis, using 114 (F9 generation) recombinant inbred lines derived from the cross between Landsberg erecta (Ler, from Poland) and Shakdara (Sha, from Tadjikistan), revealed QTLs for seed weight, plant area, dry weight, relative growth rate, chlorophyll fluorescence, flowering time, and flowering-related traits. Growth traits (plant area, dry weight, and relative growth rate) colocated at five genomic regions. At the bottom of chromosome 5, colocation was found of QTLs for leaf area, leaf initiation speed, specific leaf area, and chlorophyll fluorescence but not for dry weight, indicating that this locus might be involved in leaf development. No consistent relation between growth traits and flowering time was observed despite some colocations. Some of the QTLs detected for flowering time overlapped with loci detected in other recombinant inbred line populations, but also new loci were identified. This study shows that Arabidopsis can successfully be used to study the genetic basis of complex traits like plant growth rate.
Impact of Altered Gibberellin Metabolism on Biomass Accumulation, Lignin Biosynthesis, and Photosynthesis in Transgenic Tobacco Plants
Authors: Biemelt Sophia , Tschiersch Henning , Sonnewald Uwe
Published: May 2004

Gibberellins (GAs) are involved in regulation of many aspects during plant development. To investigate the impact of altered GA levels on plant growth and metabolism, transgenic tobacco (Nicotiana tabacum) plants have been engineered to express either a GA20-oxidase (AtGA20-ox) or a GA2-oxidase (AtGA2-ox) gene from Arabidopsis under control of the cauliflower mosaic virus 35S promoter. Resulting plants were characterized by elongated or stunted shoot growth, respectively, indicating changes in the content of bioactive GAs. In accordance with the effect on plant growth, biomass production was increased or decreased in AtGA20-ox or AtGA2-ox plants, respectively, and was found to be positively correlated with the rate of photosynthesis as determined at the whole plant level. Differences in dry matter accumulation were most likely due to changes in lignin deposition as indicated by histochemical staining and quantitative measurements. Altered lignification of transgenic plants was paralleled by up- or down-regulation of the expression of lignin biosynthetic genes. Short-term GA3 feeding of excised petioles induced lignin formation in the absence of a transcriptional activation of pathway-specific genes. Thus, short-term GA treatment mediates lignin deposition most likely by polymerization of preformed monomers, whereas long-term effects on lignification involve elevated production of precursors by transcriptional stimulation of the biosynthetic pathway. Interestingly, analysis of stem cross sections revealed a differential effect of GA on the formation of xylem and pith cells. The number of lignified vessels was increased in AtGA20-ox plants pointing to a stimulation of xylem formation while the number of pith cells declined indicating a negative regulation.
Consistency of Nicotiana attenuata's Herbivore- and Jasmonate-Induced Transcriptional Responses in the Allotetraploid Species Nicotiana quadrivalvis and Nicotiana clevelandii
Authors: Qu Nan , Schittko Ursula , Baldwin Ian T.
Published: May 2004

We examined the consistency of the native diploid Nicotiana attenuata (Na)'s herbivore-induced transcriptional changes in the two allotetraploid natives, Nicotiana clevelandii (Nc) and Nicotiana quadrivalvis (Nq), which are thought to be derived from hybridizations with an ancestral Na. An analysis of nuclear-encoded chloroplast-expressed Gln synthetase gene (ncpGS) sequences found strong similarity between Nc and Na and between N. trigonophylla and the two allopolyploids. All species were elicited with methyl jasmonate (MeJA), or were wounded and treated with either water, Manduca sexta oral secretions and regurgitant (R), or the two most abundant fatty acid amino acid conjugates (F) in R to simulate herbivory. The induced transcriptional responses in all three species were compared with a cDNA microarray enriched in Na genes. Na had the fastest transcriptional responses followed by Nc and then Nq. Na's R- and F-elicited responses were more similar to those from Nq, while the MeJA- or wound-elicited responses were more consistent in Nc. Treatment of wounds with the full cocktail of elicitors found in R elicits more complex responses than does treatment with F. The species differ in their elicited JA responses, and these differences are mirrored in the expression of oxylipin genes (LOX, HPL, AOS, and α-DOX) and downstream JA-elicited genes (TD). Elicitation decreases the expression of growth-related genes in all three species. We propose that this is a valuable system to examine the modification of complex, polygenic, adaptive responses during allopolyploid speciation.
The Key Role of Phloroglucinol O-Methyltransferase in the Biosynthesis of Rosa chinensis Volatile 1,3,5-Trimethoxybenzene
Authors: Wu Shuiqin , Watanabe Naoharu , Mita Satoru , Dohra Hideo , Ueda Yoshihiro , Shibuya Masaaki , Ebizuka Yutaka
Published: May 2004

1,3,5-Trimethoxybenzene is a key component of the Chinese rose odor. This compound is synthesized in three successive methylation steps from phloroglucinol, the initial precursor. A novel, to our knowledge, phloroglucinol O-methyltransferase (POMT) characterized here methylates the first step to produce the intermediate 3,5-dihydroxyanisole, while two previously described orcinol O-methyltransferases catalyze the subsequent steps. We isolated POMT from rose petals and determined partial amino acid sequences of the purified enzyme. The full-length POMT cDNA was isolated and expressed in Escherichia coli. Both the native and recombinant POMT exhibited substrate specificity for phloroglucinol. POMT was expressed specifically in floral organs, in accordance with its role as a key enzyme in the synthesis of rose floral scent compounds.
Yellow Stripe1. Expanded Roles for the Maize Iron-Phytosiderophore Transporter
Authors: Roberts Louis A. , Pierson Abbey J. , Panaviene Zivile , Walker Elsbeth L.
Published: May 2004

Graminaceous monocots, including most of the world's staple grains (i.e. rice, corn, and wheat) use a chelation strategy (Strategy II) for primary acquisition of iron from the soil. Strategy II plants secrete phytosiderophores (PS), compounds of the mugineic acid family that form stable Fe(III) chelates in soil. Uptake of iron-PS chelates, which occurs through specific transporters at the root surface, thus represents the primary route of iron entry into Strategy II plants. The gene Yellow stripe1 (Ys1) encodes the Fe(III)-PS transporter of maize (Zea mays). Here the physiological functions performed by maize YS1 were further defined by examining the pattern of Ys1 mRNA and protein accumulation and by defining YS1 transport specificity in detail. YS1 is able to translocate iron that is bound either by PS or by the related compound, nicotianamine; thus, the role of YS1 may be to transport either of these complexes. Ys1 expression at both the mRNA and protein levels responds rapidly to changes in iron availability but is not strongly affected by limitation of copper or zinc. Our data provide no support for the idea that YS1 is a transporter of zinc-PS, based on YS1 biochemical activity and Ys1 mRNA expression patterns in response to zinc deficiency. YS1 is capable of transporting copper-PS, but expression data suggest that the copper-PS uptake has limited significance in primary uptake of copper.
National Science Foundation-Sponsored Workshop Report. Draft Plan for Soybean Genomics
Authors: Stacey Gary , Vodkin Lila , Parrott Wayne A. , Shoemaker Randy C.
Published: May 2004

Recent efforts to coordinate and define a research strategy for soybean (Glycine max) genomics began with the establishment of a Soybean Genetics Executive Committee, which will serve as a communication focal point between the soybean research community and granting agencies. Secondly, a workshop was held to define a strategy to incorporate existing tools into a framework for advancing soybean genomics research. This workshop identified and ranked research priorities essential to making more informed decisions as to how to proceed with large scale sequencing and other genomics efforts. Most critical among these was the need to finalize a physical map and to obtain a better understanding of genome microstructure. Addressing these research needs will require pilot work on new technologies to demonstrate an ability to discriminate between recently duplicated regions in the soybean genome and pilot projects to analyze an adequate amount of random genome sequence to identify and catalog common repeats. The development of additional markers, reverse genetics tools, and bioinformatics is also necessary. Successful implementation of these goals will require close coordination among various working groups.
Rapid Genome Evolution Revealed by Comparative Sequence Analysis of Orthologous Regions from Four Triticeae Genomes
Authors: Gu Yong Qiang , Coleman-Derr Devin , Kong Xiuying , Anderson Olin D.
Published: May 2004

Bread wheat (Triticum aestivum) is an allohexaploid species, consisting of three subgenomes (A, B, and D). To study the molecular evolution of these closely related genomes, we compared the sequence of a 307-kb physical contig covering the high molecular weight (HMW)-glutenin locus from the A genome of durum wheat (Triticum turgidum, AABB) with the orthologous regions from the B genome of the same wheat and the D genome of the diploid wheat Aegilops tauschii (Anderson et al., 2003; Kong et al., 2004). Although gene colinearity appears to be retained, four out of six genes including the two paralogous HMW-glutenin genes are disrupted in the orthologous region of the A genome. Mechanisms involved in gene disruption in the A genome include retroelement insertions, sequence deletions, and mutations causing in-frame stop codons in the coding sequences. Comparative sequence analysis also revealed that sequences in the colinear intergenic regions of these different genomes were generally not conserved. The rapid genome evolution in these regions is attributable mainly to the large number of retrotransposon insertions that occurred after the divergence of the three wheat genomes. Our comparative studies indicate that the B genome diverged prior to the separation of the A and D genomes. Furthermore, sequence comparison of two distinct types of allelic variations at the HMW-glutenin loci in the A genomes of different hexaploid wheat cultivars with the A genome locus of durum wheat indicates that hexaploid wheat may have more than one tetraploid ancestor.
Calcium Interacts with Antifreeze Proteins and Chitinase from Cold-Acclimated Winter Rye
Authors: Stressmann Maja , Kitao Satoshi , Griffith Marilyn , Moresoli Christine , Bravo León A. , Marangoni Alejandro G.
Published: May 2004

During cold acclimation, winter rye (Secale cereale) plants accumulate pathogenesis-related proteins that are also antifreeze proteins (AFPs) because they adsorb onto ice and inhibit its growth. Although they promote winter survival in planta, these dual-function AFPs proteins lose activity when stored at subzero temperatures in vitro, so we examined their stability in solutions containing CaCl2, MgCl2, or NaCl. Antifreeze activity was unaffected by salts before freezing, but decreased after freezing and thawing in CaCl2 and was recovered by adding a chelator. Ca2+ enhanced chitinase activity 3- to 5-fold in unfrozen samples, although hydrolytic activity also decreased after freezing and thawing in CaCl2. Native PAGE, circular dichroism, and Trp fluorescence experiments showed that the AFPs partially unfold after freezing and thawing, but they fold more compactly or aggregate in CaCl2. Ruthenium red, which binds to Ca2+-binding sites, readily stained AFPs in the absence of Ca2+, but less stain was visible after freezing and thawing AFPs in CaCl2. We conclude that the structure of AFPs changes during freezing and thawing, creating new Ca2+-binding sites. Once Ca2+ binds to those sites, antifreeze activity, chitinase activity and ruthenium red binding are all inhibited. Because free Ca2+ concentrations are typically low in the apoplast, antifreeze activity is probably stable to freezing and thawing in planta. Ca2+ may regulate chitinase activity if concentrations are increased locally by release from pectin or interaction with Ca2+-binding proteins. Furthermore, antifreeze activity can be easily maintained in vitro by including a chelator during frozen storage.
Differential Timing of Spider Mite-Induced Direct and Indirect Defenses in Tomato Plants
Authors: Kant Merijn R. , Ament Kai , Sabelis Maurice W. , Haring Michel A. , Schuurink Robert C.
Published: May 2004

Through a combined metabolomics and transcriptomics approach we analyzed the events that took place during the first 5 d of infesting intact tomato (Lycopersicon esculentum) plants with spider mites (Tetranychus urticae). Although the spider mites had caused little visible damage to the leaves after 1 d, they had already induced direct defense responses. For example, proteinase inhibitor activity had doubled and the transcription of genes involved in jasmonate-, salicylate-, and ethylene-regulated defenses had been activated. On day four, proteinase inhibitor activity and particularly transcript levels of salicylate-regulated genes were still maintained. In addition, genes involved in phospholipid metabolism were up-regulated on day one and those in the secondary metabolism on day four. Although transcriptional up-regulation of the enzymes involved in the biosynthesis of monoterpenes and diterpenes already occurred on day one, a significant increase in the emission of volatile terpenoids was delayed until day four. This increase in volatile production coincided with the increased olfactory preference of predatory mites (Phytoseiulus persimilis) for infested plants. Our results indicate that tomato activates its indirect defenses (volatile production) to complement the direct defense response against spider mites.
Folate Biosynthesis in Higher Plants. cDNA Cloning, Heterologous Expression, and Characterization of Dihydroneopterin Aldolases
Authors: Goyer Aymeric , Illarionova Victoria , Roje Sanja , Fischer Markus , Bacher Adelbert , Hanson Andrew D.
Published: May 2004

Dihydroneopterin aldolase (EC 4.1.2.25) is one of the enzymes of folate synthesis that remains to be cloned and characterized from plants. This enzyme catalyzes conversion of 7,8-dihydroneopterin (DHN) to 6-hydroxymethyl-7,8-dihydropterin, and is encoded by the folB gene in Escherichia coli. The E. coli FolB protein also mediates epimerization of DHN to 7,8-dihydromonapterin. Searches of the Arabidopsis genome detected three genes encoding substantially diverged FolB homologs (AtFolB1–3, sharing 57%–73% identity), for which cDNAs were isolated. A fourth cDNA specifying a FolB-like protein (LeFolB1) was obtained from tomato (Lycopersicon esculentum) by reverse transcription-PCR. When overproduced in E. coli, recombinant AtFolB1, AtFolB2, and LeFolB1 proteins all had both dihydroneopterin aldolase and epimerase activities, and carried out the aldol cleavage reaction on the epimerization product, 7,8-dihydromonapterin, as well as on DHN. AtFolB3, however, could not be expressed in active form. Size exclusion chromatography indicated that the plant enzyme is an octamer, like the bacterial enzyme. Quantifying expression of the Arabidopsis genes by real-time reverse transcription-PCR showed that AtFolB1 and AtFolB2 messages occur at low levels throughout the plant, whereas the AtFolB3 mRNA was detected only in siliques and only with an extremely low abundance. Sequence comparisons and phylogenetic analysis of FolB homologs from 16 plants indicated that their N-terminal regions are highly variable, and that most species have a small number of FolB genes that diverged after separation of the lineages leading to families. The substantial divergence of FolB homologs in Arabidopsis and other plants suggests that some of them may act on substrates other than DHN.