bluuebunny/crossref_metadata_2025_split huggingface dataset:
Excision of a transposable element from a viral vector introduced into maize plants by agroinfection
Authors: Shen Wen‐Hui , Hohn Barbara 
Published: December 2004

SummaryThe geminivirus maize streak virus (MSV) was used as a vector to introduce the maize transposable element Dissociation (Ds) and to study its excision in maize plants. MSV carrying Ds1 in its genome was introduced into maize plants by agroinfection. Excision of the Ds1 element from the MSV genome was detected only when functions from the transposable element Activator (Ac) were supplied in trans, either endogenously by the recipient maize plant or by co‐transformation with Agrobacterium carrying a genomic Ac clone. The excision of Ds1 could easily be visualized by the appearance of viral symptoms induced by the revertant virus. The junction sequences left on the MSV genome after excision revealed ‘footprints’ typical of transposition as described for maize. From these results, we conclude that transposition functions in our system and that the use of the MSV replicon provides a rapid and simple tool for the investigation of the excision of transposable elements in maize plants.
Growth and stomata development of Arabidopsis hypocotyls are controlled by gibberellins and modulated by ethylene and auxins
Authors: Saibo Nelson J. M. , Vriezen Wim H. , Beemster Gerrit T. S. , Van Der Straeten Dominique 
Published: December 2004

SummaryThe plant hormones gibberellin (GA), ethylene and auxin can promote hypocotyl elongation of Arabidopsis seedlings grown in the light on a low nutrient medium (LNM). In this study, we used hypocotyl elongation as a system to investigate interactions between GA and ethylene or auxin and analysed their influence on the development of stomata in the hypocotyl. When applied together, GA and ethylene or auxin exerted a synergistic effect on hypocotyl elongation. Stimulated cell elongation is the main cause of hypocotyl elongation. Furthermore, hypocotyls treated with GA plus either ethylene or auxin show an increased endoreduplication. In addition, a small but significant increase in cell number was observed in the cortical cell files of hypocotyls treated with ethylene and GA together. However, studies with transgenic seedlings expressing CycB1::uidA genes revealed that cell division in the hypocotyl occurs only in the epidermis and mainly to form stomata, a process strictly regulated by hormones. Stomata formation in the hypocotyl is induced by the treatment with either GA or ethylene. The effect of GA could be strongly enhanced by the simultaneous addition of ethylene or auxin to the growth medium. Gibberellin is the main signal inducing stomata formation in the hypocotyl. In addition, this signal regulates hypocotyl elongation and is modulated by ethylene and auxin. The implication of these three hormones in relation to cell division and stomata formation is discussed.
Double fertilization in maize: the two male gametes from a pollen grain have the ability to fuse with egg cells
Authors: Faure Jean‐Emmanuel , Rusche Maxine Losoff , Thomas Annie , Keim Paul , Dumas Christian , Mogensen H. Lloyd , Rougier Mireille , Chaboud Annie 
Published: December 2004

SummaryIn flowering plants, two male gametes from a single pollen grain fuse with two female gametes, the egg and central cells, to form the embryo and endosperm, respectively. The question then arises whether the two male gametes fuse randomly with the egg and central cells. We investigated this question using two nearly isogenic maize lines with supernumerary B chromosomes (TB10L18) or without (r‐tester). B chromosomes regularly undergo non‐disjunction at the second pollen mitosis, producing one sperm cell with zero B chromosomes and one with two. We first confirmed earlier studies showing an excess of transmission of the B chromosomes to the embryo rather than to the endosperm. We then tested the possibility of a directed fertilization. For TB10L18 pollen, we could demonstrate the existence of a size dimorphism between the two sperm cells, correlated to the content in B chromosomes, as detected by fluorescence in situ hybridization (FISH). However, no directed fusion of B chromosome containing sperm to egg cells could be detected when using in vitro fertilization. The absence of directed fusion in vitro could also be demonstrated for control lines. We conclude that both male gametes have the capacity to fuse with the egg cell in maize, although sexual reproduction results in a preferential transmission of supernumerary B chromosomes.
The role of PopCel1 and PopCel2 in poplar leaf growth and cellulose biosynthesis
Authors: Ohmiya Yasunori , Nakai Tomonori , Park Yong Woo , Aoyama Takashi , Oka Atsuhiro , Sakai Fukumi , Hayashi Takahisa 
Published: December 2004

SummaryPoplar calli transcribed two cellulase (endo‐1,4‐β‐glucanase) genes, PopCel1 and PopCel2, whose mRNAs were differentially located in the growing leaves of poplar during cell wall synthesis. Histochemical and RT‐PCR analyses of promoter–GUS fusion gene activities in transgenic poplar demonstrated that PopCel1 promoter‐derived GUS activity was localized in the petiole and leaf veins, whereas PopCel2 was confined to mesophyll cells and disappeared from the tip during the development of leaves. Autoradiography of the leaf showed that the radioactivity of [14C]sucrose incorporated into cellulose corresponded to the combination of the sucrose‐induced tissue‐specific patterns of PopCel1 and PopCel2. Interestingly, 2,6‐dichlorobenzonitrile (DCB) not only inhibited the incorporation of the radioactivity into cellulose, but also repressed the induction of both cellulase genes. Suppression of cellulases by expression of PopCel1 antisense cDNA or co‐suppression of PopCel1 mRNA by overexpression of PopCel1 sense cDNA reduced leaf growth. Therefore, we came to the conclusion that PopCel1 and PopCel2 probably function to promote leaf growth in poplar by the endohydrolysis of 1,4‐β‐glucan.
Transport of cytokinins mediated by purine transporters of the PUP family expressed in phloem, hydathodes, and pollen of Arabidopsis
Authors: Bürkle Lukas , Cedzich Anna , Döpke Corinna , Stransky Harald , Okumoto Sakiko , Gillissen Bernd , Kühn Christina , Frommer Wolf B. 
Published: December 2004

SummaryNucleobases and derivatives like cytokinins and caffeine are translocated in the plant vascular system. Transport studies in cultured Arabidopsis cells indicate that adenine and cytokinin are transported by a common H+‐coupled high‐affinity purine transport system. Transport properties are similar to that of Arabidopsis purine transporters AtPUP1 and 2. When expressed in yeast, AtPUP1 and 2 mediate energy‐dependent high‐affinity adenine uptake, whereas AtPUP3 activity was not detectable. Similar to the results from cell cultures, purine permeases (PUP) mediated uptake of adenine can be inhibited by cytokinins, indicating that cytokinins are transport substrates. Direct measurements demonstrate that AtPUP1 is capable of mediating uptake of radiolabeled trans‐zeatin. Cytokinin uptake is strongly inhibited by adenine and isopentenyladenine but is poorly inhibited by 6‐chloropurine. A number of physiological cytokinins including trans‐ and cis‐zeatin are also efficient competitors for AtPUP2‐mediated adenine uptake, suggesting that AtPUP2 is also able to mediate cytokinin transport. Furthermore, AtPUP1 mediates transport of caffeine and ribosylated purine derivatives in yeast. Promoter–reporter gene studies point towards AtPUP1 expression in the epithem of hydathodes and the stigma surface of siliques, suggesting a role in retrieval of cytokinins from xylem sap to prevent loss during guttation. The AtPUP2 promoter drives GUS reporter gene activity in the phloem of Arabidopsis leaves, indicating a role in long‐distance transport of adenine and cytokinins. Promoter activity of AtPUP3 was only found in pollen. In summary, three closely related PUPs are differentially expressed in Arabidopsis and at least two PUPs have properties similar to the adenine and cytokinin transport system identified in Arabidopsis cell cultures.
Growth suppression, altered stomatal responses, and augmented induction of heat shock proteins in cytosolic ascorbate peroxidase (Apx1)‐deficient Arabidopsis plants
Authors: Pnueli Lilach , Liang Hongjian , Rozenberg Mira , Mittler Ron 
Published: December 2004

SummaryThe accumulation of hydrogen peroxide (H2O2) in plants is typically associated with biotic or abiotic stresses. However, H2O2 is continuously produced in cells during normal metabolism. Yet, little is known about how H2O2 accumulation will affect plant metabolism in the absence of pathogens or abiotic stress. Here, we report that a deficiency in the H2O2‐scavenging enzyme, cytosolic ascorbate peroxidase (APX1), results in the accumulation of H2O2 in Arabidopsis plants grown under optimal conditions. Knockout‐Apx1 plants were characterized by suppressed growth and development, altered stomatal responses, and augmented induction of heat shock proteins during light stress. The inactivation of Apx1 resulted in the induction of several transcripts encoding signal transduction proteins. These were not previously linked to H2O2 signaling during stress and may belong to a signal transduction pathway specifically involved in H2O2 sensing during normal metabolism. Surprisingly, the expression of transcripts encoding H2O2 scavenging enzymes, such as catalase or glutathione peroxidase, was not elevated in knockout‐Apx1 plants. The expression of catalase, two typical plant peroxidases, and several different heat shock proteins was however elevated in knockout‐Apx1 plants during light stress. Our results demonstrate that in planta accumulation of H2O2 can suppress plant growth and development, interfere with different physiological processes, and enhance the response of plants to abiotic stress conditions. Our findings also suggest that at least part of the induction of heat shock proteins during light stress in Arabidopsis is mediated by H2O2 that is scavenged by APX1.
The translation initiation factor eIF1A is an important determinant in the tolerance to NaCl stress in yeast and plants
Authors: Rausell Antonio , Kanhonou Rodolphe , Yenush Lynne , Serrano Ramon , Ros Roc 
Published: December 2004

SummaryProtein synthesis is very sensitive to NaCl. However, the molecular targets responsible for this sensitivity have not been described. A cDNA library of the halotolerant plant sugar beet was functionally screened in a sodium‐sensitive yeast strain. We obtained a cDNA clone (BveIF1A) encoding the eukaryotic translation initiation factor eIF1A. BveIF1A was able to partially complement the yeast eIF1A‐deficient strain. Overexpression of the sugar beet eIF1A specifically increased the sodium and lithium salt tolerance of yeast. This phenotype was not accompanied by changes in sodium or potassium homeostasis. Under salt stress conditions, yeast cells expressing BveIF1A presented a higher rate of amino acid incorporation into proteins than control cells. In an in vitro protein synthesis system from wheat germ, the BveIF1A recombinant protein improved translation in the presence of NaCl. Finally, transgenic Arabidopsis plants expressing BveIF1A exhibited increased tolerance to NaCl. These results suggest that the translation initiation factor eIF1A is an important determinant of sodium tolerance in yeast and plants.
Theabi1‐1mutation blocks ABA signaling downstream of cADPR action
Authors: Wu Yan , Sanchez Juan Pablo , Lopez‐Molina Luis , Himmelbach Axel , Grill Erwin , Chua Nam‐Hai 
Published: December 2004

SummaryArabidopsis thaliana abscisic acid insensitive 1‐1(abi1‐1) is a dominant mutant that is insensitive to the inhibition of germination and growth by the plant hormone, abscisic acid (ABA). The mutation severely decreases the catalytic activity of the ABI1 type 2C protein phosphatase (PP2C). However, the site of action of theabi1‐1/ABI1 in the ABA signal transduction pathway has not yet been determined. Using single cell assays, we showed that microinjecting mutant abi1‐1 protein inhibited the activation ofRD29A‐GUSandKIN2‐GUSin response to ABA, cyclic ADP‐ribose (cADPR), and Ca2+. The inhibitory effect of the mutant protein, however, was reversed by co‐microinjection of an excess amount of the ABI1 protein. In transgenicArabidopsisplants, overexpression ofabi1‐1rendered the plants insensitive to ABA during germination, whereas overexpression of ABI1 did not have any apparent effect. Moreover, transgenic plants overexpressingabi1‐1were blocked in the induction of ABA‐responsive genes; however, overexpression of ABI1 did not affect gene expression. Taken together, our results demonstrate thatabi1‐1is likely to be a dominant negative mutation and ABI1 likely acts downstream of cADPR in the ABA‐signaling pathway. Our results on ABI1 overexpression inArabidopsisare not compatible with a negative regulatory role of this phosphatase in ABA responses.
Genome analysis at different ploidy levels allows cloning of the powdery mildew resistance gene Pm3b from hexaploid wheat
Authors: Yahiaoui Nabila , Srichumpa Payorm , Dudler Robert , Keller Beat 
Published: December 2004

SummaryIn wheat, race‐specific resistance to the fungal pathogen powdery mildew (Blumeria graminis f. sp. tritici) is controlled by the Pm genes. There are 10 alleles conferring resistance at the Pm3 locus (Pm3a to Pm3j) on chromosome 1AS of hexaploid bread wheat (Triticum aestivum L.). The genome of hexaploid wheat has a size of 1.6 × 1010 bp and contains more than 80% of repetitive sequences, making positional cloning difficult. Here, we demonstrate that the combined analysis of genomes from wheat species with different ploidy levels can be exploited for positional cloning in bread wheat. We have mapped the Pm3b gene in hexaploid wheat to a genetic interval of 0.97 centimorgan (cM). The diploid T. monococcum and the tetraploid T. turgidum ssp. durum provided models for the A genome of hexaploid wheat and allowed to establish a physical contig spanning the Pm3 locus. Although the haplotypes at the Pm3 locus differed markedly between the three species, a large resistance gene‐like family specific to wheat group 1 chromosomes was consistently found at the Pm3 locus. A candidate gene for Pm3b was identified using partial sequence conservation between resistant line Chul and T. monococcum cv. DV92. A susceptible Pm3b mutant, carrying a single‐base pair deletion in the coding region of the candidate gene was isolated. When tested in a single cell transformation assay, the Pm3b candidate gene conferred race‐specific resistance to powdery mildew. These results demonstrate that the candidate gene, a member of the coiled‐coil nucleotide binding site leucine‐rich repeat (NBS‐LRR) type of disease resistance genes, is the Pm3b gene.
Risk factors for urinary tract calculi in Trinidad
Authors: Anatol Trevor , Pereira Lexley Pinto , Simeon Donald , Sawh Lall 
Published: December 2004

Summaryobjective  To identify risk factors for urinary tract stones in Trinidad and Tobago.methods  A consecutive series of patients presenting to institutions in Trinidad for the management of proven urinary tract calculi was interviewed by questionnaires designed to obtain data on age, gender, ethnicity, occupation, stone location, a family history of stone disease, a past history of certain medical diseases and a semiquantitative estimate of the magnesium intake in food, ‘over the counter’ drugs and drinking water. An equivalent number of patients attending the same institutions for follow‐up and verified from hospital records as having a previous radiological diagnosis of urinary tract stones, as well as a group of asymptomatic members of the community working in the same area, underwent the same interview. Chi‐square, anova and Kruskal–Wallis tests were used to examine differences between the groups. Multiple logistic regression analysis was used to determine persistence of the significance of these differences after controlling for confounding variables.results  Data sufficient for analysis were obtained for 122 previous and 102 prospective patients and 102 controls. The mean age of the patients was 32 years. The ratio of males to females was 0.9–1.8:1 for the affected groups, but significantly more males than females had calculi in the lower urinary tract (19%vs. 6%; P = 0.004). More patients (30%) than controls (7%) gave a positive family history of urinary tract stone disease (P < 0.001). Affected persons had a lower dietary magnesium intake (P = 0.003), which accounted for a significantly lower total magnesium intake (P = 0.02). Logistic regression analysis of the variables studied indicated that independent predictors of the disease were a positive family history (P = 0.001), total magnesium intake (P = 0.001) and age (P < 0.001).conclusion  A low magnesium intake and a positive family history are highly predictive of urinary tract calculi in this population.
The effect on haemoglobin of the use of iron cooking pots in rural Malawian households in an area with high malaria prevalence: a randomized trial
Authors: Geerligs Paul Prinsen , Brabin Bernard , Mkumbwa Albert , Broadhead Robin , Cuevas Luis E. 
Published: December 2004

Summarybackground  Innovative low‐cost sustainable strategies are required to reduce the high prevalence of iron‐deficiency anaemia in developing countries.methods  We undertook a community‐based randomized controlled intervention trial to assess the effects of cooking in iron or aluminium cooking pots in Malawian households in an area with high malaria prevalence. Analysis was by intention to treat and consistency of use. The primary outcomes were change in haemoglobin and iron status.findings  The study population comprised 164 participants eating from aluminium cooking pots and 158 from iron cooking pots. The mean haemoglobin change was significantly increased after 6 weeks in adults who consistently ate from an iron cooking pot (+3.6 g/l compared to −3.2 g/l, mean difference between groups 6.8 g/l, 95% CI +0.86, +12.74). In children, no significant haemoglobin change was observed in consistent pot users, although they showed a significant reduction in iron deficiency (iron 8.6 ZP/g and aluminium 10.8 ZP/g, mean difference 2.2 ZP/g, 95% CI +1.08, +3.32).interpretation  Rural Malawian adults in a high malaria transmission area who consistently consume food prepared in iron cooking pots show a significant rise in haemoglobin after 6 weeks use. Children showed a reduction in iron deficiency, but no significant improvement in haemoglobin, possibly because of their high malaria parasite prevalence. Using iron cooking pots in developing countries could provide an innovative way to prevent iron deficiency and anaemia in malarious areas where regular iron supplementation is problematic.
Private practitioners and tuberculosis control in the Philippines: strangers when they meet?
Authors: Portero J. L. , Rubio M. 
Published: December 2004

Summaryobjective To investigate the knowledge, attitudes and perspectives of the Filipino private physicians (PPs) on tuberculosis (TB) control issues in the Philippines and their implications for future governmental public health policies.design Cross‐sectional telephone survey from June to October 2001.participants In each of the 78 provinces of the Philippines we randomly selected 10 PPs from the provincial capital city, five PPs from an urban centre with more than 50 000 population, and one PP from 15 rural villages with <50 000 population, making a total of 30 PPs per province. These data were complemented with information from focus group discussions with health workers and policy makers working in TB control, and through personal interviews with PPs.results We interviewed 1355 (57.9%) of 2340 PPs identified. TB was diagnosed mainly through X‐ray (87.9%) and usually treated with inappropriate regimens of anti‐TB drugs (89.3%). The PPs did not follow‐up their TB patients, did not trace the defaulters (97.9%) and did not identify contacts (91.4%). Only 24.2% knew the National Tuberculosis Programme (NTP) policies in depth. They defined the NTP's weakest points as diagnosis through sputum microscopy (59.2%) and the management of smear negative patients (29.7%). Most PPs were willing to collaborate with the NTP (83.3%) provided they were paid (38.4%). More than a half (51.5%) objected to obligatory reporting of new TB cases. The PPs based their success in attracting TB patients to their offices on confidentiality (46.1%) and on the kind treatment and flexibility given (43.7%).conclusions Diagnosis and treatment of TB patients is a daily issue for the PPs in the Philippines, although they did not follow usually the NTP guidelines. The majority of the PPs wished to collaborate with the NTP provided they were paid.
Absence of the kdr mutation in the molecular ‘M’ form suggests different pyrethroid resistance mechanisms in the malaria vector mosquito Anopheles gambiae s.s.
Authors: Awolola T. S. , Brooke B. D. , Koekemoer L. L. , Coetzee M. 
Published: December 2004

SummaryField tests conducted on adult Anopheles mosquitoes using standard WHO procedures, diagnostic kits and test papers in south‐western Nigeria showed pyrethroid (deltamethrin and permethrin) resistance in adult populations of Anopheles gambiae sensu stricto. The knock‐down resistance (kdr) mutation involved in pyrethroid resistance was only found in the molecular S form of An. gambiae s.s. even in area where both molecular M and S forms occurred in sympatry. The absence of the kdr mutation in the M form suggests an additional pyrethroid resistance mechanism in An. gambiae s.s.
Présence d'Angiostrongylus cantonensis en Haïti
Authors: Raccurt Christian P. , Blaise Jacques , Durette‐Desset Marie‐Claude 
Published: December 2004

ResuméL'angiostrongylose nerveuse due àAngiostrongylus (Parastrongylus) cantonensis est une zoonose qui a été signalée dans la majorité des régions d'Asie méridionale et orientale, du Pacifique, de l'Océan indien, en Australie, dans quelques pays d'Afrique et de la Caraïbe. Sur 23 rats capturés en Haiti, 7 ont été parasités par des angiostrongyles dans les cavités droites du cœur ou dans les artères pulmonaires. Haïti est ainsi la dernière des grandes Antilles où la présence de A. cantonensis est confirmée. L'impact de ce parasite sur la santé humaine en Haïti n'est pas connu. Il demanderait àêtre évalué d'autant que 1,3% des décès recensés pendant l'année 1999 étaient dus à une méningite d'étiologie inconnue.
An estimation of the incidence of noma in north‐west Nigeria
Authors: Fieger Alexander , Marck Klaas W. , Busch Raymonde , Schmidt Andreas 
Published: December 2004

SummaryNoma (cancrum oris, stomatitis gangrenosa) is a quickly spreading orofacial gangrene in children, caused by a combination of malnutrition, debilitation because of concomitant diseases (measles) and intraoral infections. The global incidence of noma in the world is uncertain. By comparing large numbers of noma patients and cleft lip patients in a large referral hospital for these disorders in Sokoto, Nigeria, we calculated the incidence of noma in north‐west Nigeria as 6.4 per 1000 children. Extrapolation of this incidence to the developing countries bordering the Sahara Desert (the noma belt of the world) gives an incidence of 25 600 for that region and a global incidence of 30 000–40 000. Noma is a good biological parameter of extreme poverty, and hence a global monitoring system for noma can be justified. Though economic progress is the most effective preventive measure against noma, medical prevention by vaccination programmes against measles should be enhanced as well.