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1.
Proc Natl Acad Sci U S A ; 118(41)2021 10 12.
Artigo em Inglês | MEDLINE | ID: mdl-34607952

RESUMO

Humans have made such dramatic and permanent changes to Earth's landscapes that much of it is now substantially and irreversibly altered from its preanthropogenic state. Remote islands, until recently isolated from humans, offer insights into how these landscapes evolved in response to human-induced perturbations. However, little is known about when and how remote systems were colonized because archaeological data and historical records are scarce and incomplete. Here, we use a multiproxy approach to reconstruct the initial colonization and subsequent environmental impacts on the Azores Archipelago. Our reconstructions provide unambiguous evidence for widespread human disturbance of this archipelago starting between 700-60+50 and 850-60+60 Common Era (CE), ca. 700 y earlier than historical records suggest the onset of Portuguese settlement of the islands. Settlement proceeded in three phases, during which human pressure on the terrestrial and aquatic ecosystems grew steadily (i.e., through livestock introductions, logging, and fire), resulting in irreversible changes. Our climate models suggest that the initial colonization at the end of the early Middle Ages (500 to 900 CE) occurred in conjunction with anomalous northeasterly winds and warmer Northern Hemisphere temperatures. These climate conditions likely inhibited exploration from southern Europe and facilitated human settlers from the northeast Atlantic. These results are consistent with recent archaeological and genetic data suggesting that the Norse were most likely the earliest settlers on the islands.


Assuntos
Ecossistema , Meio Ambiente , Atividades Humanas , Migração Humana , Agricultura , Açores , Mudança Climática , Modelos Climáticos , Fezes/química , Humanos
2.
Ecol Lett ; 26(5): 729-741, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-36958810

RESUMO

Human-mediated changes in island vegetation are, among others, largely caused by the introduction and establishment of non-native species. However, data on past changes in non-native plant species abundance that predate historical documentation and censuses are scarce. Islands are among the few places where we can track human arrival in natural systems allowing us to reveal changes in vegetation dynamics with the arrival of non-native species. We matched fossil pollen data with botanical status information (native, non-native), and quantified the timing, trajectories and magnitude of non-native plant vegetational change on 29 islands over the past 5000 years. We recorded a proportional increase in pollen of non-native plant taxa within the last 1000 years. Individual island trajectories are context-dependent and linked to island settlement histories. Our data show that non-native plant introductions have a longer and more dynamic history than is generally recognized, with critical implications for biodiversity baselines and invasion biology.


Assuntos
Biodiversidade , Plantas , Humanos , Pólen , Ilhas , Espécies Introduzidas
4.
Theor Appl Genet ; 131(8): 1761-1776, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29802449

RESUMO

KEY MESSAGE: The nonhost resistance of wild lettuce to lettuce downy mildew seems explained by four components of a putative set of epistatic genes. The commonplace observation that plants are immune to most potential pathogens is known as nonhost resistance (NHR). The genetic basis of NHR is poorly understood. Inheritance studies of NHR require crosses of nonhost species with a host, but these crosses are usually unsuccessful. The plant-pathosystem of lettuce and downy mildew, Bremia lactucae, provides a rare opportunity to study the inheritance of NHR, because the nonhost wild lettuce species Lactuca saligna is sufficiently cross-compatible with the cultivated host Lactuca sativa. Our previous studies on NHR in one L. saligna accession led to the hypothesis that multi-locus epistatic interactions might explain NHR. Here, we studied NHR at the species level in nine accessions. Besides the commonly used approach of studying a target trait from a wild donor species in a cultivar genetic background, we also explored the opposite, complementary approach of cultivar introgression in a wild species background. This bidirectional approach encompassed (1) nonhost into host introgression: identification of L. saligna derived chromosome regions that were overrepresented in highly resistant BC1 plants (F1 × L. sativa), (2) host into nonhost introgression: identification of L. sativa derived chromosome regions that were overrepresented in BC1 inbred lines (F1 × L. saligna) with relatively high infection levels. We demonstrated that NHR is based on resistance factors from L. saligna and the genetic dose for NHR differs between accessions. NHR seemed explained by combinations of epistatic genes on three or four chromosome segments, of which one chromosome segment was validated by the host into nonhost approach.


Assuntos
Resistência à Doença/genética , Epistasia Genética , Genes de Plantas , Lactuca/genética , Doenças das Plantas/genética , Cruzamentos Genéticos , Lactuca/microbiologia , Oomicetos , Doenças das Plantas/microbiologia
5.
Theor Appl Genet ; 127(8): 1805-16, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24927822

RESUMO

KEY MESSAGE: In a stacking study of eight resistance QTLs in lettuce against downy mildew, only three out of ten double combinations showed an increased resistance effect under field conditions. Complete race nonspecific resistance to lettuce downy mildew, as observed for the nonhost wild lettuce species Lactuca saligna, is desired in lettuce cultivation. Genetic dissection of L. saligna's complete resistance has revealed several quantitative loci (QTL) for resistance with field infection reductions of 30-50 %. To test the effect of stacking these QTL, we analyzed interactions between homozygous L. saligna CGN05271 chromosome segments introgressed into the genetic background of L. sativa cv. Olof. Eight different backcross inbred lines (BILs) with single introgressions of 30-70 cM and selected predominately for quantitative resistance in field situations were intercrossed. Ten developed homozygous lines with stacked introgression segments (double combinations) were evaluated for resistance in the field. Seven double combinations showed a similar infection as the individual most resistant parental BIL, revealing epistatic interactions with 'less-than-additive' effects. Three double combinations showed an increased resistance level compared to their parental BILs and their interactions were additive, 'less-than-additive' epistatic and 'more-than-additive' epistatic, respectively. The additive interaction reduced field infection by 73 %. The double combination with a 'more-than-additive' epistatic effect, derived from a combination between a susceptible and a resistant BIL with 0 and 30 % infection reduction, respectively, showed an average field infection reduction of 52 %. For the latter line, an attempt to genetically dissect its underlying epistatic loci by substitution mapping did not result in smaller mapping intervals as none of the 22 substitution lines reached a similar high resistance level. Implications for breeding and the inheritance of L. saligna's complete resistance are discussed.


Assuntos
Resistência à Doença/genética , Lactuca/genética , Lactuca/microbiologia , Oomicetos/fisiologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Locos de Características Quantitativas/genética , Mapeamento Cromossômico , Cruzamentos Genéticos , Epistasia Genética , Genótipo , Hibridização Genética , Endogamia , Lactuca/imunologia , Doenças das Plantas/microbiologia
6.
Mol Plant Microbe Interact ; 26(11): 1259-70, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23883357

RESUMO

Breeding lettuce (Lactuca sativa) for resistance to the downy mildew pathogen Bremia lactucae is mainly achieved by introgression of dominant downy mildew resistance (Dm) genes. New Bremia races quickly render Dm genes ineffective, possibly by mutation of recognized host-translocated effectors or by suppression of effector-triggered immunity. We have previously identified 34 potential RXLR(-like) effector proteins of B. lactucae that were here tested for specific recognition within a collection of 129 B. lactucae-resistant Lactuca lines. Two effectors triggered a hypersensitive response: BLG01 in 52 lines, predominantly L. saligna, and BLG03 in two L. sativa lines containing Dm2 resistance. The N-terminal sequences of BLG01 and BLG03, containing the signal peptide and GKLR variant of the RXLR translocation motif, are not required for in planta recognition but function in effector delivery. The locus responsible for BLG01 recognition maps to the bottom of lettuce chromosome 9, whereas recognition of BLG03 maps in the RGC2 cluster on chromosome 2. Lactuca lines that recognize the BLG effectors are not resistant to Bremia isolate Bl:24 that expresses both BLG genes, suggesting that Bl:24 can suppress the triggered immune responses. In contrast, lettuce segregants displaying Dm2-mediated resistance to Bremia isolate Bl:5 are responsive to BLG03, suggesting that BLG03 is a candidate Avr2 protein.


Assuntos
Resistência à Doença , Interações Hospedeiro-Patógeno , Lactuca/genética , Oomicetos/genética , Doenças das Plantas/imunologia , Proteínas/genética , Alelos , Motivos de Aminoácidos , Sequência de Aminoácidos , Cruzamento , Mapeamento Cromossômico , Cromossomos de Plantas/genética , Regulação da Expressão Gênica , Lactuca/imunologia , Lactuca/parasitologia , Dados de Sequência Molecular , Família Multigênica , Oomicetos/crescimento & desenvolvimento , Oomicetos/fisiologia , Fenótipo , Doenças das Plantas/parasitologia , Folhas de Planta , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Sinais Direcionadores de Proteínas , Transporte Proteico , Proteínas/metabolismo , Alinhamento de Sequência
7.
Theor Appl Genet ; 126(12): 2995-3007, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24037018

RESUMO

KEY MESSAGE: Three regions with quantitative resistance to downy mildew of non-host and wild lettuce species, Lactuca saligna , disintegrate into seventeen sub-QTLs with plant-stage-dependent effects, reducing or even promoting the infection. Previous studies on the genetic dissection of the complete resistance of wild lettuce, Lactuca saligna, to downy mildew revealed 15 introgression regions that conferred plant stage dependent quantitative resistances (QTLs). Three backcross inbred lines (BILs), carrying an individual 30-50 cM long introgression segment from L. saligna in a cultivated lettuce, L. sativa, background, reduced infection by 60-70 % at young plant stage and by 30-50 % at adult plant stage in field situations. We studied these three quantitative resistances in order to narrow down their mapping interval and determine their number of loci, either single or multiple. We performed recombinant screenings and developed near isogenic lines (NILs) with smaller overlapping L. saligna introgressions (substitution mapping). In segregating introgression line populations, recombination was suppressed up to 17-fold compared to the original L. saligna × L. sativa F 2 population. Recombination suppression depended on the chromosome region and was stronger suppressed at the smallest introgression lengths. Disease evaluation of the NILs revealed that the resistance of all three BILs was not explained by a single locus but by multiple sub-QTLs. The 17 L. saligna-derived sub-QTLs had a smaller and plant stage dependent resistance effect, some segments reducing; others even promoting downy mildew infection. Implications for lettuce breeding are outlined.


Assuntos
Mapeamento Cromossômico , Resistência à Doença/genética , Imunidade Inata/genética , Lactuca/genética , Lactuca/imunologia , Peronospora/fisiologia , Doenças das Plantas/microbiologia , Locos de Características Quantitativas , Cromossomos de Plantas/genética , DNA de Plantas/genética , Genes de Plantas/genética , Marcadores Genéticos/genética , Lactuca/crescimento & desenvolvimento , Lactuca/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia
8.
Appl Environ Microbiol ; 78(16): 5956-61, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22685156

RESUMO

The bacteriocin enterocin A (EntA) produced by Enterococcus faecium T136 has been successfully cloned and produced by the yeasts Pichia pastoris X-33EA, Kluyveromyces lactis GG799EA, Hansenula polymorpha KL8-1EA, and Arxula adeninivorans G1212EA. Moreover, P. pastoris X-33EA and K. lactis GG799EA produced EntA in larger amounts and with higher antimicrobial and specific antimicrobial activities than the EntA produced by E. faecium T136.


Assuntos
Bacteriocinas/biossíntese , Bacteriocinas/genética , Clonagem Molecular , Enterococcus faecium/genética , Leveduras/genética , Leveduras/metabolismo , Antibacterianos/biossíntese , Antibacterianos/farmacologia , Bacteriocinas/farmacologia , Enterococcus faecium/metabolismo
9.
Plant Cell ; 21(10): 3368-78, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19855048

RESUMO

Some inter- and intraspecific crosses may result in reduced viability or sterility in the offspring, often due to genetic incompatibilities resulting from interactions between two or more loci. Hybrid necrosis is a postzygotic genetic incompatibility that is phenotypically manifested as necrotic lesions on the plant. We observed hybrid necrosis in interspecific lettuce (Lactuca sativa and Lactuca saligna) hybrids that correlated with resistance to downy mildew. Segregation analysis revealed a specific allelic combination at two interacting loci to be responsible. The allelic interaction had two consequences: (1) a quantitative temperature-dependent autoimmunity reaction leading to necrotic lesions, lethality, and quantitative resistance to an otherwise virulent race of Bremia lactucae; and (2) a qualitative temperature-independent race-specific resistance to an avirulent race of B. lactucae. We demonstrated by transient expression and silencing experiments that one of the two interacting genes was Rin4. In Arabidopsis thaliana, RIN4 is known to interact with multiple R gene products, and their interactions result in hypersensitive resistance to Pseudomonas syringae. Site-directed mutation studies on the necrosis-eliciting allele of Rin4 in lettuce showed that three residues were critical for hybrid necrosis.


Assuntos
Quimera/metabolismo , Quimera/microbiologia , Lactuca/metabolismo , Lactuca/microbiologia , Necrose/genética , Oomicetos/patogenicidade , Proteínas de Plantas/fisiologia , Quimera/genética , Imunidade Inata/genética , Imunidade Inata/fisiologia , Lactuca/genética , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Temperatura
10.
FEMS Yeast Res ; 12(8): 924-37, 2012 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22900669

RESUMO

Fumarate reductase is an enzyme involved in maintaining redox balance through regeneration of reduced cofactors during oxygen deficiency conditions. This work reports the identification and characterization of the gene and its promoter and terminator elements that encodes cytosolic fumarate reductase enzyme in the nonconventional yeast, Arxula adeninivorans. The gene harbours an ORF of 1446 bp, encoding a 482-amino acid protein. The deduced amino acid sequence is similar to those of fumarate reductases from other yeast and fungi, such as the two fumarate reductases of Saccharomyces cerevisiae, Frd1p (44%) and Osm1p (41%). This enzyme is located in the cytosol and has a pH optimum of ca. 7.5 and a Michaelis constant (K(M)) of 2.9 mM with fumarate as the substrate. Expression of AFRD1 is regulated by the cultivation conditions. A shift from NaCl-free to NaCl-supplemented media and aerobic to hypoxic growth conditions leads to reduced AFRD1 transcription levels, but not to alteration in the concentration of Afrd1p. The functional analyses of Afrd1p were performed in A. adeninivorans and S. cerevisiae disruption mutants. The A. adeninivorans fumarate reductase is capable of functional complementation of the missing S. cerevisiae genes during anoxia; however, it is not involved in yeast growth under osmotic stress.


Assuntos
Proteínas Fúngicas/metabolismo , Saccharomycetales/enzimologia , Saccharomycetales/genética , Succinato Desidrogenase/metabolismo , Sequência de Aminoácidos , Hipóxia Celular , Clonagem Molecular , Meios de Cultura , DNA Fúngico/genética , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica , Concentração de Íons de Hidrogênio , Dados de Sequência Molecular , Mutação , Pressão Osmótica , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , Saccharomycetales/crescimento & desenvolvimento , Análise de Sequência de DNA , Succinato Desidrogenase/genética
11.
Sci Total Environ ; 830: 154828, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35346708

RESUMO

A multiproxy approach was applied to a sediment core retrieved from the deep crater Lake Funda, located in the middle of the North Atlantic Ocean on Flores Island, Azores archipelago (Portugal). The purpose of this study was to determine how this ecosystem responded to natural and anthropogenic forces over the last millennium. We distinguished three main phases in lake evolution using multiproxy reconstructions and documentary sources. (A) Climate and lake catchment processes, as well as internal ones, were the main drivers of ecosystem variability before 1335 CE, when human disturbances were absent in the Lake Funda catchment. (B) The second phase is marked by unprecedented changes in all studied proxies between 1335 and 1560 CE, including abrupt changes in the composition and diversity of diatom and chironomid assemblages. Synergistic effects from high climate variability and the onset of human disturbances in the catchment (e.g., introduction of livestock) during the Medieval Climate Anomaly-Little Ice Age transition, led to an increase in lake trophic state from mesotrophic to eutrophic conditions. (C) In the last phase (1560 CE to the present), the eutrophic conditions in Lake Funda were maintained through a positive feedback loop between lake productivity and in-lake phosphorous recycling. Variability within the lake ecosystem was mainly associated with climate variability and internal lake dynamics (e.g., phosphorus remobilization). Our results show that a paleoecological approach is crucial to understanding lake ecological states in the present-day in order to develop locally adapted management and restoration strategies. A long-term perspective enables us to understand the harmful consequences of ongoing climate change and human disturbances on lake ecosystems.


Assuntos
Diatomáceas , Ecossistema , Efeitos Antropogênicos , Mudança Climática , Humanos , Lagos
12.
Appl Microbiol Biotechnol ; 92(1): 105-14, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21559827

RESUMO

Tannase (tannin acyl hydrolase, EC 3.1.1.20) hydrolyses the ester and depside bonds of gallotannins and gallic acid esters and is an important industrial enzyme. In the present study, transgenic Arxula adeninivorans strains were optimised for tannase production. Various plasmids carrying one or two expression modules for constitutive expression of tannase were constructed. Transformant strains that overexpress the ATAN1 gene from the strong A. adeninivorans TEF1 promoter produce levels of up to 1,642 U L(-1) when grown in glucose medium in shake flasks. The effect of fed-batch fermentation on tannase productivity was then investigated in detail. Under these conditions, a transgenic strain containing one ATAN1 expression module produced 51,900 U of tannase activity per litre after 142 h of fermentation at a dry cell weight of 162 g L(-1). The highest yield obtained from a transgenic strain with two ATAN1 expression modules was 31,300 U after 232 h at a dry cell weight of 104 g L(-1). Interestingly, the maximum achieved yield coefficients [Y(P/X)] for the two strains were essentially identical.


Assuntos
Hidrolases de Éster Carboxílico/metabolismo , Saccharomycetales/metabolismo , Hidrolases de Éster Carboxílico/genética , Expressão Gênica , Vetores Genéticos , Organismos Geneticamente Modificados/genética , Organismos Geneticamente Modificados/metabolismo , Plasmídeos , Regiões Promotoras Genéticas , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomycetales/genética
13.
Med Phys ; 48(3): 1448-1455, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33411339

RESUMO

PURPOSE: Pencil beam scanning (PBS) for moving targets is known to be impacted by interplay effects. Four-dimensional computed tomography (4DCT)-based motion evaluation is crucial for understanding interplay and developing mitigation strategies. Availability of high-quality 4DCTs with variable breathing traces is limited. Purpose of this work is the development of a framework for interplay analysis using 4D-XCAT phantoms in conjunction with time-resolved irradiation patterns in a commercial treatment planning system (TPS). Four-dimensional dynamically accumulated dose distributions (4DDDs) are simulated in an in-silico study for a PBS liver treatment. METHODS: An XCAT phantom with 50 phases, varying linearly in amplitude each by 1 mm, was combined with the RayStation TPS (7.99.10). Deformable registration was used with time-resolved dose calculation, mapping XCAT phases to motion signals. To illustrate the applicability of the method a two-field liver irradiation plan was used. A variety sin4 type motion signals, varying in amplitude (1-20 mm), period (1.6-5.2 s) and phase (0-2π) were applied. Either single variable variations or random combinations were selected. The interplay effect within a clinical target (5 cm diameter) was characterized in terms of homogeneity index (HI5), with and without five paintings. In total 2092 scenarios were analyzed within RayStation. RESULTS: A framework is presented for interplay research, allowing for flexibility in determining motion management techniques, increasing reproducibility, and enabling comparisons of different methods. A case study showed the interplay effect was correlated with amplitude and strongly affected by the starting phase, leading to large variance. The average of all scenarios (single fraction) resulted in HI5 of 0.31 (±0.11), while introduction of five times layered repainting reduced this to 0.11(±0.03). CONCLUSION: The developed framework, which uses the XCAT phantom and RayStation, allows detailed analysis of motion in context of PBS with comparable results to clinical cases. Flexibility in defining motion patterns for detailed anatomies in combination with time-resolved dose calculation, facilitates investigation of optimal treatment and motion mitigation strategies.


Assuntos
Terapia com Prótons , Tomografia Computadorizada Quadridimensional , Imagens de Fantasmas , Planejamento da Radioterapia Assistida por Computador , Reprodutibilidade dos Testes , Respiração
14.
Science ; 372(6541): 488-491, 2021 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-33926949

RESUMO

Islands are among the last regions on Earth settled and transformed by human activities, and they provide replicated model systems for analysis of how people affect ecological functions. By analyzing 27 representative fossil pollen sequences encompassing the past 5000 years from islands globally, we quantified the rates of vegetation compositional change before and after human arrival. After human arrival, rates of turnover accelerate by a median factor of 11, with faster rates on islands colonized in the past 1500 years than for those colonized earlier. This global anthropogenic acceleration in turnover suggests that islands are on trajectories of continuing change. Strategies for biodiversity conservation and ecosystem restoration must acknowledge the long duration of human impacts and the degree to which ecological changes today differ from prehuman dynamics.


Assuntos
Biodiversidade , Atividades Humanas , Ilhas , Humanos , Pólen
15.
Yeast ; 26(2): 83-93, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19191338

RESUMO

In Arxula adeninivorans nitrate assimilation is mediated by the combined actions of a nitrate transporter, a nitrate reductase and a nitrite reductase. Single-copy genes for these activities (AYNT1, AYNR1, AYNI1, respectively) form a 9103 bp gene cluster localized on chromosome 2. The 3210 bp AYNI1 ORF codes for a protein of 1070 amino acids, which exhibits a high degree of identity to nitrite reductases from the yeasts Pichia anomala (58%), Hansenula polymorpha (58%) and Dekkera bruxellensis (54%). The second ORF (AYNR1, 2535 bp) encodes a nitrate reductase of 845 residues that shows significant (51%) identity to nitrate reductases of P. anomala and H. polymorpha. The third ORF in the cluster (AYNT1, 1518 bp) specifies a nitrate transporter with 506 amino acids, which is 46% identical to that of H. polymorpha. The three genes are independently expressed upon induction with NaNO(3). We quantitatively analysed the promoter activities by qRT-PCR and after fusing individual promoter fragments to the phytase (phyK) gene from Klebsiella sp. ASR1. The AYNI1 promoter was found to exhibit the highest activity, followed by the AYNT1 and AYNR1 elements. Direct measurements of nitrate and nitrite reductase activities performed after induction with NaNO(3) are compatible with these results. Both enzymes show optimal activity at around 42 degrees C and near-neutral pH, and require FAD as a co-factor and NADPH as electron donor.


Assuntos
Regulação Fúngica da Expressão Gênica , Família Multigênica , Nitratos/metabolismo , Saccharomycetales/metabolismo , Proteínas de Transporte de Ânions/genética , Proteínas de Transporte de Ânions/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Dados de Sequência Molecular , Nitrato Redutase/genética , Nitrato Redutase/metabolismo , Transportadores de Nitrato , Nitrito Redutases/genética , Nitrito Redutases/metabolismo , Regiões Promotoras Genéticas , Saccharomycetales/enzimologia , Saccharomycetales/genética , Saccharomycetales/crescimento & desenvolvimento , Análise de Sequência de DNA
16.
Yeast ; 26(6): 323-37, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19387973

RESUMO

The tannase-encoding Arxula adeninivorans gene ATAN1 was isolated from genomic DNA by PCR, using as primers oligonucleotide sequences derived from peptides obtained after tryptic digestion of the purified tannase protein. The gene harbours an ORF of 1764 bp, encoding a 587-amino acid protein, preceded by an N-terminal secretion sequence comprising 28 residues. The deduced amino acid sequence was similar to those of tannases from Aspergillus oryzae (50% identity), A. niger (48%) and putative tannases from A. fumigatus (52%) and A. nidulans (50%). The sequence contains the consensus pentapeptide motif (-Gly-X-Ser-X-Gly-) which forms part of the catalytic centre of serine hydrolases. Expression of ATAN1 is regulated by the carbon source. Supplementation with tannic acid or gallic acid leads to induction of ATAN1, and accumulation of the native tannase enzyme in the medium. The enzymes recovered from both wild-type and recombinant strains were essentially indistinguishable. A molecular mass of approximately 320 kDa was determined, indicating that the native, glycosylated tannase consists of four identical subunits. The enzyme has a temperature optimum at 35-40 degrees C and a pH optimum at approximately 6.0. The enzyme is able to remove gallic acid from both condensed and hydrolysable tannins. The wild-type strain LS3 secreted amounts of tannase equivalent to 100 U/l under inducing conditions, while the transformant strain, which overexpresses the ATAN1 gene from the strong, constitutively active A. adeninivorans TEF1 promoter, produced levels of up to 400 U/l when grown in glucose medium in shake flasks.


Assuntos
Hidrolases de Éster Carboxílico/metabolismo , Proteínas Fúngicas/metabolismo , Saccharomycetales/enzimologia , Sequência de Aminoácidos , Hidrolases de Éster Carboxílico/química , Hidrolases de Éster Carboxílico/genética , Clonagem Molecular , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Ácido Gálico/metabolismo , Concentração de Íons de Hidrogênio , Dados de Sequência Molecular , Peso Molecular , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomycetales/genética , Saccharomycetales/crescimento & desenvolvimento , Homologia de Sequência de Aminoácidos , Taninos/metabolismo , Temperatura , Ativação Transcricional
17.
FEMS Yeast Res ; 9(3): 468-77, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19260971

RESUMO

In many fungal species, cell growth and morphology, thermo- and osmotolerance are regulated by mitogen-activated protein kinase (MAPk) cascades. Ste11p is a MAP kinase kinase kinase, which plays a central role in various pathways in Saccharomyces cerevisiae. Here we describe ASTE11, an STE11 homologue from Arxula adeninivorans, an imperfect, dimorphic, but nonpathogenic and extremophilic yeast. ASTE11 lacks introns, and codes for a protein of 824 amino acids with a predicted molecular weight of 91.6 kDa. The gene is constitutively expressed at low levels, but is induced by high-salt stress. To facilitate functional analysis of ASTE11, disruption and overexpressing mutants were constructed. The phenotypes of these strains indicate that Aste11p is involved in regulating aspects of cell wall structure and form, but is dispensable for adaptation to hypertonic stress. Despite its structural homology to STE11, ASTE11 cannot complement the mating defect of S. cerevisiae ste11 mutants. These findings emphasize that, although components of MAPk pathways are conserved among yeasts, they often operate in different contexts in different species.


Assuntos
Parede Celular/fisiologia , Proteínas Fúngicas/fisiologia , MAP Quinase Quinase Quinases/fisiologia , Saccharomycetales/fisiologia , Estresse Fisiológico , Sequência de Aminoácidos , DNA Fúngico/química , DNA Fúngico/genética , Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Dosagem de Genes , Perfilação da Expressão Gênica , Técnicas de Inativação de Genes , Íntrons , MAP Quinase Quinase Quinases/química , MAP Quinase Quinase Quinases/genética , Dados de Sequência Molecular , Peso Molecular , Pressão Osmótica , Filogenia , Proteínas de Saccharomyces cerevisiae , Saccharomycetales/enzimologia , Alinhamento de Sequência , Análise de Sequência de DNA
18.
Appl Microbiol Biotechnol ; 84(3): 583-94, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19672589

RESUMO

Combining ease of genetic manipulation and fermentation with the ability to secrete and to glycosylate proteins in the basic eukaryotic manner, Arxula adeninivorans provides an attractive expression platform. Based on a redesign of the basic vector, a new Arxula vector system, Xplor 2, for heterologous gene expression was established, which allows (1) the construction of expression plasmids for supertransformation of A. adeninivorans strains secreting target proteins of biotechnological interest and (2) the integration of small vector cassettes consisting of yeast DNA sequences only. For this purpose, a set of modules including the ATRP1m selection-marker module, expression modules for constitutive expression of the genes phyK (Klebsiella-derived phytase) and IFNalpha2a (human interferon alpha), the HARS (Hansenula polymorpha autonomous replication sequence) for autonomous replication and the chaperone module AHSB4 promoter -HpCNE1 gene (calnexin) -PHO5 terminator to improve secretion efficiency were constructed and integrated in various combinations in the basic vector Xplor 2. After removal of the complete Escherichia coli-based plasmid parts (resistance marker, ColE1 ori and f1(-) origin), the remaining yeast-based linear vector fragment with or without rDNA targeting sequences were transformed as yeast rDNA integrative expression cassettes and yeast integrative expression cassettes (YICs), respectively, and the resulting strains were tested for their capacity to secrete PhyK or IFNalpha2a. Maximal expression levels were consistently obtained using YICs for transformation irrespective of whether or not they carry HARS and/or calnexin modules. It is recommended that at least 50 such transformants be analyzed to ensure selection of the best transformants.


Assuntos
6-Fitase/metabolismo , Biotecnologia/métodos , Regulação Fúngica da Expressão Gênica , Vetores Genéticos , Proteínas Recombinantes/metabolismo , Saccharomycetales/metabolismo , Transformação Genética , 6-Fitase/genética , Humanos , Interferon alfa-2 , Interferon-alfa/genética , Interferon-alfa/metabolismo , Klebsiella/enzimologia , Klebsiella/genética , Proteínas Recombinantes/genética , Saccharomycetales/genética
19.
Genetics ; 211(1): 263-276, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30401697

RESUMO

Interspecific crosses can result in progeny with reduced vitality or fertility due to genetic incompatibilities between species, a phenomenon known as hybrid incompatibility (HI). HI is often caused by a bias against deleterious allele combinations, which results in transmission ratio distortion (TRD). Here, we determined the genome-wide distribution of HI between wild lettuce, Lactuca saligna, and cultivated lettuce, L. sativa, in a set of backcross inbred lines (BILs) with single introgression segments from L. saligna introgressed into a L. sativa genetic background. Almost all BILs contained an introgression segment in a homozygous state except a few BILs, for which we were able to obtain only a single heterozygous introgression. Their inbred progenies displayed severe TRD with a bias toward the L. sativa allele and complete nontransmission of the homozygous L. saligna introgression, i.e., absolute HI. These HI might be caused by deleterious heterospecific allele combinations at two loci. We used an multilocus segregating interspecific F2 population to identify candidate conspecific loci that can nullify the HI in BILs. Segregation analysis of developed double-introgression progenies showed nullification of three HI and proved that these HI are explained by nuclear pairwise incompatibilities. One of these digenic HI showed 29% reduced seed set and its pattern of TRD pointed to a sex-independent gametophytic barrier. Namely, this HI was caused by complete nontransmission of one heterospecific allele combination at the haploid stage, surprisingly in both male and female gametophytes. Our study shows that two-locus incompatibility systems contribute to reproductive barriers among Lactuca species.


Assuntos
Células Germinativas Vegetais/fisiologia , Hibridização Genética , Lactuca/genética , Infertilidade das Plantas/genética , Endogamia , Lactuca/fisiologia
20.
Neuropsychiatr Dis Treat ; 14: 317-326, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29398916

RESUMO

OBJECTIVE: To investigate the evidence-based treatment of catatonia in adults. The secondary aim is to develop a treatment protocol. MATERIALS AND METHODS: A systematic review of published treatment articles (case series, cohort or randomized controlled studies) which examined the effects of particular interventions for catatonia and/or catatonic symptoms in adult populations and used valid outcome measures was performed. The articles for this review were selected by searching the electronic databases of the Cochrane Library, MEDLINE, EMBASE and PSYCHINFO. RESULTS: Thirty-one articles met the inclusion criteria. Lorazepam and electroconvulsive therapy (ECT) proved to be the most investigated treatment interventions. The response percentages in Western studies varied between 66% and 100% for studies with lorazepam, while in Asian and Indian studies, they were 0% and 100%. For ECT, the response percentages are 59%-100%. There does not seem to be evidence for the use of antipsychotics in catatonic patients without any underlying psychotic disorder. CONCLUSION: Lorazepam and ECT are effective treatments for which clinical evidence is found in the literature. It is not possible to develop a treatment protocol because the evidence for catatonia management on the basis of the articles reviewed is limited. Stringent treatment studies on catatonia are warranted.

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