Mostrando recursos 1 - 20 de 25

  1. Mucoid morphotype variation of Burkholderia multivorans during chronic cystic fibrosis lung infection is correlated with changes in metabolism, motility, biofilm formation and virulence

    Silva, I.N.; Ferreira, A.S.; Becker, J.D.; Zlosnik, J.E.A.; Speert, D.P.; He, J.; Mil-Homens, D.; Moreira, L.M.
    Burkholderia cepacia complex (Bcc) bacteria are opportunistic pathogens infecting hosts such as cystic fibrosis (CF) patients. Long-term Bcc infection of CF patients' airways has been associated with emergence of phenotypic variation. Here we studied two Burkholderia multivorans clonal isolates displaying different morphotypes from a chronically infected CF patient to evaluate trait development during lung infection. Expression profiling of mucoid D2095 and non-mucoid D2214 isolates revealed decreased expression of genes encoding products related to virulence-associated traits and metabolism in D2214. Furthermore, D2214 showed no exopolysaccharide production, lower motility and chemotaxis, and more biofilm formation, particularly under microaerophilic conditions, than the clonal...

  2. Laser-microdissection unravels cell-type specific transcription in > arbuscular mycorrhizal roots, including CAAT-box TF gene expression correlating with fungal contact and spread

    Hogekamp, C.; Arndt, D.; Pereira, P.A.; Becker, J.D.; Hohnjec, N.; Kuster, H.
    Arbuscular mycorrhizae (AM) are the most widespread symbioses on Earth, promoting nutrient supply of most terrestrial plant species. To unravel gene expression in defined stages of Medicago truncatula root colonization by AM fungi, we here combined genome-wide transcriptome profiling based on whole mycorrhizal roots with real-time RT-PCR experiments that relied on characteristic cell-types obtained via laser-microdissection. Our genome-wide approach delivered a core set of 512 genes significantly activated by the two mycorrhizal fungi Glomus intraradices and Glomus mossae. Focussing on 62 of these genes being related to membrane transport, signaling, and transcriptional regulation, we distinguished whether they are activated in...

  3. MicroRNA activity in the Arabidopsis male germline

    Borges, F.; Pereira, P.A.; Slotkin, R.K.; Martienssen, R.A.; Becker, J.D.
    Most of the core proteins involved in the microRNA (miRNA) pathway in plants have been identified, and almost simultaneously hundreds of miRNA sequences processed in the Arabidopsis sporophyte have been discovered by exploiting next-generation sequencing technologies. However, there is very limited understanding about potentially distinct mechanisms of post-transcriptional regulation between different cell lineages. In this review the focus is on the Arabidopsis male gametophyte (pollen), where the germline differentiates after meiosis giving rise to the male gametes. Based on comparative analysis of miRNAs identified in sperm cells by in-depth sequencing, their possible functions during germ cell specification and beyond fertilization...

  4. Genomic Expression Program Involving the Haalp-Regulation in Saccharomyces cerevisiae response to acetic acid

    Mira, N.P.; Becker, J.D.; Sa-Correia, I.
    The alterations occurring in yeast genomic expression during early response to acetic acid and the involvement of the transcription factor Haa1p in this transcriptional reprogramming are described in this study. Haa1p was found to regulate, directly or indirectly, the transcription of approximately 80% of the acetic acid-activated genes, suggesting that Haa1p is the main player in the control of yeast response to this weak acid. The genes identified in this work as being activated in response to acetic acid in a Haa1p-dependent manner include protein kinases, multidrug resistance transporters, proteins involved in lipid metabolism, in nucleic acid processing, and proteins...

  5. A genome-wide survey of sRNAs in the symbiotic nitrogen-fixing alpha-proteobacterium Sinorhizobium meliloti

    Schluter, J.P.; Reinkensmeier, J.; Daschkey, S.; Evguenieva-Hackenberg, E.; Janssen, S.; Janicke, S.; Becker, J.D.; Giegerich, R.; Becker, A.
    A total of 1,125 sRNA candidates that were classified as trans-encoded sRNAs (173), cis-encoded antisense sRNAs (117), mRNA leader transcripts (379), and sense sRNAs overlapping coding regions (456) were identified in a size range of 50 to 348 nucleotides. Among these were transcripts corresponding to 82 previously reported sRNA candidates. Enrichment for RNAs with primary 5'-ends prior to sequencing of cDNAs suggested transcriptional start sites corresponding to 466 predicted sRNA regions. The consensus sigma70 promoter motif CTTGAC-N17-CTATAT was found upstream of 101 sRNA candidates. Expression patterns derived from microarray hybridizations provided further information on conditions of expression of a number...

  6. A genomewide survey of sRNAs in the symbiotic nitrogen-fixing alpha-proteobacterium Sinorhizobium meliloti

    Schluter, J.P.; Reinkensmeier, J.; Daschkey, S.; Evguenieva-hackenberg, E.; Janssen, S.; Janicke, S.; Becker, J.D.; Giegerich, R.; Becker, A.
    A total of 1,125 sRNA candidates that were classified as trans-encoded sRNAs (173), cis-encoded antisense sRNAs (117), mRNA leader transcripts (379), and sense sRNAs overlapping coding regions (456) were identified in a size range of 50 to 348 nucleotides. Among these were transcripts corresponding to 82 previously reported sRNA candidates. Enrichment for RNAs with primary 5'-ends prior to sequencing of cDNAs suggested transcriptional start sites corresponding to 466 predicted sRNA regions. The consensus sigma70 promoter motif CTTGAC-N17-CTATAT was found upstream of 101 sRNA candidates. Expression patterns derived from microarray hybridizations provided further information on conditions of expression of a number...

  7. Quantitative genetics of functional characters in Drosophila melanogaster populations subjected to laboratory selection

    Teotónio, H; Matos, M; Rose, MR
    What are the genetics of phenotypes other than fitness, in outbred populations? To answer this question. the quantitative-genetic basis of divergence was characterized for outbred Drosophila melanogaster populations that had previously undergone selection to enhance characters related to fitness. Line-cross analysis using first-generation and second-generation hybrids from reciprocal crosses was conducted for two types of cross, each replicated fivefold. One type of cross was between representatives of the ancestral population, a set of five populations maintained for several hundred generations on a two-week discrete-generation life cycle and a set of five populations adapted to starvation stress. The other type of...

  8. Genetic variation for outcrossing among Caenorhabditis elegans isolates

    Teotónio, H; Manoel, D; Phillips, PC
    The evolution of breeding systems results from the existence of genetic variation and selective forces favoring different outcrossing rates. In this study we determine the extent of genetic variation for characters directly related to outcrossing, such as male frequency, male mating ability, and male reproductive success, in several wild isolates of the nematode Caenorhabditis elegans. This species is characterized by an androdioecious breeding system in which males occur with hermaphrodites that can either self-fertilize or outcross with males. We find genetic variation for all characters measured, but also find that environmental variation is a large fraction of the total phenotypic...

  9. Selection against males in Caenorhabditis elegans under two mutational treatments

    Manoel, D; Carvalho, S; Phillips, PC; Teotonio, H
    Within populations with mixed mating systems, selfing is expected to be favoured over outcrossing unless a countervailing process such as severe inbreeding depression is present. In this study, we consider the relationship between the expression of deleterious alleles and the maintenance of outcrossing in the nematode species, Caenorhabditis elegans. This species is characterized by an androdioecious breeding system composed of males at low frequency and self-fertilizing hermaphrodites that can only outcross via males. Here, we find that experimentally increasing the mutational load in four different isogenic wild isolates using 10 generations of Ethylmethane sulphonate (EMS) and UV irradiation mutagenesis significantly...

  10. Absence of functional TolC protein causes increased stress response gene expression in Sinorhizobium meliloti

    Santos, Mario R.; Cosme, Ana M.; Becker, Jorg D.; Medeiros, Joao M C.; Mata, Marcia F.; Moreira, Leonilde M.
    The TolC protein from Sinorhizobium meliloti has previously been demonstrated to be required for establishing successful biological nitrogen fixation symbiosis with Medicago sativa. It is also needed in protein and exopolysaccharide secretion and for protection against osmotic and oxidative stresses. Here, the transcriptional profile of free-living S. meliloti 1021 tolC mutant is described as a step toward understanding its role in the physiology of the cell.

  11. Comparative transcriptomics of Arabidopsis sperm cells

    Borges, Filipe Filipe; Gomes, Gabriela; Gardner, Rui; Moreno, Nuno; McCormick, Sheila; Feijo, Jose A. Jose A.; Becker, Joeg D Joeg D
    n flowering plants, the two sperm cells are embedded within the cytoplasm of the growing pollen tube and as such are passively transported to the embryo sac, wherein double fertilization occurs upon their release. Understanding the mechanisms and conditions by which male gametes mature and take part in fertilization are crucial goals in the study of plant reproduction. Studies of gene expression in male gametes of maize (Zea mays) and Plumbago and in lily (Lilium longiflorum) generative cells already showed that the previously held view of transcriptionally inert male gametes was not true, but genome-wide studies were lacking. Analyses in...

  12. BOLITA, an Arabidopsis AP2/ERF-like transcription factor that affects cell expansion and proliferation/differentiation pathways

    Marsch-Martinez, Nayelli; Greco, Raffaella; Becker, Jorg D.; Dixit, Shital; Bergervoet, Jan H. W.; Karaba, Aarati Aarati; de Folter, Stefan; Pereira, Andy
    The BOLITA (BOL) gene, an AP2/ERF transcription factor, was characterized with the help of an activation tag mutant and overexpression lines in Arabidopsis and tobacco. The leaf size of plants overexpressing BOL was smaller than wild type plants due to a reduction in both cell size and cell number. Moreover, severe overexpressors showed ectopic callus formation in roots. Accordingly, global gene expression analysis using the overexpression mutant reflected the alterations in cell proliferation, differentiation and growth through expression changes in RBR, CYCD, and TCP genes, as well as genes involved in cell expansion (i.e. expansins and the actin remodeling factor...

  13. How many genes are needed to make a pollen tube? lessons from transcriptomics

    Becker, Jorg D.; Feijó, José A
    Background Pollen is the male gametophyte of higher plants. Upon pollination, it germinates and develops into a fast-growing cytoplasmic extension, the pollen tube, which ultimately delivers the sperm into the ovary. The biological relevance of its role, and the uniqueness of this kind of cellular organization, have made pollen the focus of many approaches, and it stands today as one of the best-known models in plant cell biology. In contrast, the genetic background of its development has been until recently largely unknown. Some genes involved have been described and a few functional mutants have been characterized, but only to a...

  14. The making of gametes in higher plants

    Boavida, L.; Becker, J.D.; Feijó, J.A.
    Higher plants have evolved to be one of the predominant life forms on this planet. A great deal of this evolutionary success relies in a very short gametophytic phase which underlies the sexual reproduction cycle. Sexual plant reproduction takes place in special organs of the flower. In most species the processes of gametogenesis, pollination, syngamy and embryogenesis are sequentially coordinated to give rise to a functional seed in a matter of few weeks. Any of these processes is so intricately complex and precisely regulated that it becomes no wonder that each involves more specific genes and cellular processes than any...

  15. Transcriptional profiling of arabidopsis tissues reveals the Unique Characteristics of the pollen transcriptome

    Becker, J.D.; Boavida, L.C.; Carneiro, J.; Haury, M.; Feijó, J.A.
    Pollen tubes are a good model for the study of cell growth and morphogenesis because of their extreme elongation without cell division. Yet, knowledge about the genetic basis of pollen germination and tube growth is still lagging behind advances in pollen physiology and biochemistry. In an effort to reduce this gap, we have developed a new method to obtain highly purified, hydrated pollen grains of Arabidopsis through flowcytometric sorting, and we used GeneChips (Affymetrix, Santa Clara, CA; representing approximately 8,200 genes) to compare the transcriptional profile of sorted pollen with those of four vegetative tissues (seedlings, leaves, roots, and siliques)....

  16. Signalling by tips

    Feijó, J.A.; Costa, S.S.; Prado, A.M.; Becker, J.D.; Certal, A.C.
    New molecules, including protein kinases, lipids and molecules that have neurotransmitter activities in animals have emerged as important players in tip-growing cells. Transcriptomics analysis reveals that the largest single class of genes expressed in pollen tubes encode signal transducers, reflecting the necessity to decode complex and diverse pathways that are associated with tip growth. Many of these pathways may use common intracellular second messengers, with ions and reactive oxygen species emerging as two major common denominators in many of the processes involved in tip growth. These second messengers might influence the actin cytoskeleton through known interactions with actin-binding proteins. In turn, changes in the dynamic properties of the cytoskeleton would define the basic...

  17. The nodulin VfENOD18 is an ATP-binding protein in infected cells of Vicia faba L. nodules

    Becker, J.D.; Moreira, L.M.; Kapp, D.; Frosch S.C.; Pühler A.; Perlick, A.M.
    Recently we described the novel nodulin gene VfENOD18, whose corresponding transcripts were restricted to the nitrogen-fixing zone III of broad bean root nodules. To characterize VfENOD18 on the protein level, polyclonal antibodies were generated using the purified recombinant VfENOD18 protein produced in Escherichia coli by employing the pMAL-c expression system. These antibodies recognized immunoreactive proteins isolated from indeterminate nodules of different leguminous plants, but also from non-symbiotic tissues of Glycine max and from tissues of Arabidopsis thaliana and Zea mays. Using immunogold labelling the nodulin VfENOD18 was localized to the cytoplasm of infected cells in the nitrogen-fixing zone of broad...

  18. Gene family analysis of the Arabidopsis pollen transcriptome reveals biological implications for cell growth, division control and gene expression regulation

    Pina, C.; Pinto, F.; Feijó, J.A.; Becker, J.D.
    Upon germination, pollen forms a tube that elongates dramatically through female tissues to reach and fertilize ovules. While essential for the life cycle of higher plants, the genetic basis underlying most of the process is not well understood. We previously used a combination of flow cytometry sorting of viable hydrated pollen grains and GeneChip array analysis of onethird of the Arabidopsis (Arabidopsis thaliana) genome to define a first overview of the pollen transcriptome. We now extend that study to approximately 80% of the genome of Arabidopsis by using Affymetrix Arabidopsis ATH1 arrays and perform comparative analysis of gene family and gene ontology representation in the...

  19. BOLITA, an Arabidopsis AP2/ERF-like transcription factor that

    Marsch-Martinez, N.; Greco, F.; Becker, JD; Dixit, S.; Karaba, A.; Bergervoet, J.; de Folter, S.
    The BOLITA (BOL) gene, an AP2/ERF transcription factor, was characterized with the help of an activation tag mutant and overexpression lines in Arabidopsis and tobacco. The leaf size of plants overexpressing BOL was smaller than wild type plants due to a reduction in both cell size and cell number. Moreover, severe overexpressors showed ectopic callus formation in roots. Accordingly, global gene expression analysis using the overexpression mutant reflected the alterations in cell proliferation, differentiation and growth through expression changes in RBR, CYCD, and TCP genes, as well as genes involved in cell expansion (i.e. expansins and the actin remodeling factor ADF5). Furthermore, the expression of hormone signaling (i.e. auxin and cytokinin), biosynthesis (i.e. ethylene...

  20. Gametophyte interaction and sexual reproduction: how plants make a zygote

    Boavida, L.C.; Vieira, A.M.; Becker, J.D.; Feijó, J.A.
    The evolutionary success of higher plants relies on a very short gametophytic phase, which underlies the sexual reproduction cycle. Sexual plant reproduction takes place in special organs of the flower: pollen, the male gametophyte, is released from the anthers and then adheres, grows and interacts along various tissues of the female organs, collectively known as the pistil. Finally, it fertilizes the female gametophyte, the embryo sac. Pollen is released as bi or tricellular, highly de-hydrated and presumably containing all the biochemical components and transcripts to germinate. Upon hydration on the female tissues, it develops a cytoplasmic extension, the pollen tube,...

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