152 research outputs found
Ploidy stability in embryogenic cultures and regenerated plantlets of tamarillo
Ploidy levels of short-term (1 and 2 years) and
long-term (7 and 10 years) embryogenic cultures as well as
of regenerated plantlets of tamarillo were analyzed by flow
cytometry and chromosome counts. Embryogenic cultures
were induced from expanding leaves cultured in the presence
of Picloram or 2,4-dichlorophenoxyacetic acid (2,4-D) and
monthly subcultured on the same media. Embryo development
and plantlets were obtained following subculture of the
embryogenic tissue in auxin free medium containing gibberellic
acid (GA3). Seedlings and rooted shoots from axillary
shoot proliferation were used as controls. The results
showed that in long-term embryogenic cultures the ability
to develop somatic embryos and plantlets was reduced.
Embryogenic tissues maintained for 10 years were mostly
aneuploids of the tetraploid (2n = 4x = 48) level whereas
those kept in culture for 7 years or less were also mostly
aneuploids but of the diploid (2n = 2x = 24) level. The
results obtained by flow cytometry were, in general, consistent
with those obtained by chromosome counts. The chromosome
alteration observed in the embryogenic tissues was
already present after 1 year of culture and increased with
culture age, hence impairing the maintenance of these tissues
for long periods without affecting chromosome stability
of the regenerated plantlets. However, the occurrence of
triploids and tetraploids as well as aneuploids can be useful
for breeding purposes. A value around 23 pg/2C was found
for the genome size of tamarillo largely exceeding the value
previously published (15.50 pg/2C).This work was supported by the Portuguese
Foundation for Science and Technology (FCT)
The Arena: An indoor mixed reality space
ln this paper, we introduce the Arena, an indoor space for mobile mixed reality interaction. The Arena includes a new user tracking system appropriate for AR/MR applications and a new Too/kit oriented to the augmented and mixed reality applications developer, the MX Too/kit. This too/kit is defined at a somewhat higher abstraction levei, by hiding from the programmer low-level implementation details and facilitating ARJMR object-oriented programming. The system handles, uniformly, video input, video output (for headsets and monitors), sound aurelisation and Multimodal Human-Computer Interaction in ARJMR, including, tangible interfaces, speech recognition and gesture recognition.info:eu-repo/semantics/publishedVersio
Um Caso Único de Hemorragia Digestiva Alta Recorrente Causada por Duas Lesões de Dieulafoy Metácronas: a Importância da Avaliação por Ecoendoscopia
Introduction: Dieulafoy's lesion (DL) is a rare but important cause of acute, severe, life-threatening, and recurrent upper gastrointestinal bleeding (UGIB). It is frequently difficult to diagnose DL with upper GI endoscopy (UGIE), and endoscopic ultrasonography (EUS) may be valuable. There are only 2 reported bleeding cases caused by two synchronous DL but no reported cases of two metachronous DL.
Case report: A 28-year-old healthy male presented with acute severe UGIB. UGIE was inconclusive. Systematic EUS mapping identified a gastric DL. After several attempts of EUS-guided hemostasis, DL was marked using a through-the-scope clip and the patient underwent successful transcatheter arterial embolization (TAE). Three years later, a new severe UGIB episode was caused by a second gastric DL in a different location, which was identified and marked by EUS and further successfully treated through TAE. The patient maintained follow-up without evidence of further bleeding.
Discussion/conclusion: The authors report a unique case of severe, recurrent UGIB caused by two metachronous gastric DL lesions. The importance of systematic EUS scanning for diagnosis, treatment, and follow-up of DL is emphasized, as well as the potential influence in the outcome of other techniques like angiographic embolization.info:eu-repo/semantics/publishedVersio
Psicopatologia e encefalopatia hepática
Desde Hipócrates que as alterações psiquiátricas causadas por doença hepática têm fascinado os médicos, mas só em finais do
século XIX é que Marcel Nencki e Ivan Pavlov
sugeriram a relação entre o aumento
de concentração de amónia e a Encefalopatia
Hepática (EH). O fruto da reacção entre
a amónia e o glutamato (a glutamina, verdadeiro “Cavalo de Tróia da neurotoxidade
da amónia”) continua sendo considerado o
principal responsável pelas lesões neurológicas, confirmadas recentemente através de estudos de neuroquímica e de neuroimagiologia. A glutamina espoleta processos inflamatórios
a nível do sistema nervoso central
para os quais parecem também contribuir
o manganésio, e os sistemas neurotransmissores
gabaérgico e endocanabinóides.
Actualmente consideram-se três grandes
grupos etiológicos, qualitativos, de EH: tipo
A associada a falência hepática aguda; tipo
B associada a bypass porto-sistémico; e tipo
C associada a insuficiência hepática crónica
por cirrose. Quanto ao estadiamento clínico,
este ainda se baseia no sistema West Haven,
mas com a novidade da introdução de um
Grau 0 pré-clínico (a chamada EH Mínima);
à medida que agrava a EH pode ser quantificada entre o Grau 1 (com alterações subtis ao exame médico), e o Grau 4 (onde se instala o estado comatoso). Neste trabalho pretende-se fazer uma revisão bibliográfica de 30 artigos recentes, que focam os vários aspectos psicopatológicos,
fisiopatológicos, etiológicos e de
estadiamento nesta entidade clínica transversal à Psiquiatria e à Gastrenterologia. São descritas a nível da vigilidade e consciência: a desorientação no tempo, espaço e pessoa. Ao nível da atenção, concentração e memória há alteração dos testes neuropsicológicos logo na fase pré-clínica. O humor pode oscilar
entre o eufórico e o depressivo.
As alterações da personalidade podem instalar-se de forma óbvia e abrupta ou de forma subtil e insidiosa. Na percepção há alucinações visuais mas também acústico-verbais. O pensamento pode ser delirante paranóide, sistematizado ou não. O discurso poderá estar acelerado, lentificado ou imperceptível.
O insight surge prejudicado na EH Mínima,
nomeadamente para a capacidade de condução
de veículos. Na vida instintiva, várias
perturbações de sono atingem metade dos
doentes com EH; o apetite surge diminuído
mas foi descrito pelo menos um caso de
pica; enquanto que a libido poderá parecer
aumentada em contexto de uma desinibição
semelhante à verificada nas lesões do lobo
pré-frontal
Design of a high power production target for the Beam Dump Facility at CERN
The Beam Dump Facility (BDF) project is a proposed general-purpose facility
at CERN, dedicated to beam dump and fixed target experiments. In its initial
phase, the facility is foreseen to be exploited by the Search for Hidden
Particles (SHiP) experiment. Physics requirements call for a pulsed 400 GeV/c
proton beam as well as the highest possible number of protons on target (POT)
each year of operation, in order to search for feebly interacting particles.
The target/dump assembly lies at the heart of the facility, with the aim of
safely absorbing the full high intensity Super Proton Synchrotron (SPS) beam,
while maximizing the production of charmed and beauty mesons. High-Z materials
are required for the target/dump, in order to have the shortest possible
absorber and reduce muon background for the downstream experiment. The high
average power deposited on target (305 kW) creates a challenge for heat
removal. During the BDF facility Comprehensive Design Study (CDS), launched by
CERN in 2016, extensive studies have been carried out in order to define and
assess the target assembly design. These studies are described in the present
contribution, which details the proposed design of the BDF production target,
as well as the material selection process and the optimization of the target
configuration and beam dilution. One of the specific challenges and novelty of
this work is the need to consider new target materials, such as a molybdenum
alloy (TZM) as core absorbing material and Ta2.5W as cladding.
Thermo-structural and fluid dynamics calculations have been performed to
evaluate the reliability of the target and its cooling system under beam
operation. In the framework of the target comprehensive design, a preliminary
mechanical design of the full target assembly has also been carried out,
assessing the feasibility of the whole target system.Comment: 17 pages, 18 figure
Plant genotype influences aquatic-terrestrial ecosystem linkages through timing and composition of insect emergence
Terrestrial leaf litter provides aquatic insects with an energy source and habitat structure,and species differences in litter can influence aquatic insect emergence. Emerging insects also provide energy to riparian predators. We hypothesized that plant genetics would influence the composition and timing of emerging insect communities among individual genotypes of Populus angustifolia varying in litter traits. We also compared the composition and timing of emerging insect communities on litter from mixed genotypes of three cross types of a hybridizing cottonwood complex: P. angustifolia, P. fremontii, and their F1 hybrids. Using litter harvested from an experimental common garden, we measured emerging insect community composition, abundance, and production for 12 weeks in large litter packs affixed with emergence traps. Five major findings emerged. (1) In support of the genetic similarity hypothesis, we found that, among P. angustifolia tree genotypes, litter from more closely related genotypes had more similar litter thickness, nitrogen concentrations, decomposition rates, and emerging insect communities. (2) Genetic similarity was not correlated with other litter traits, although the litter fungal community was a strong predictor of emerging insect communities. (3) Litter decomposition rate, which was the strongest predictor of emerging aquatic insect communities, was influenced by litter thickness, litter N, and the litter fungal community. (4) In contrast to strong community composition differences among P. angustifolia genotypes, differences in community composition between P. fremontii and P. angustifolia were only marginally significant, and communities on F1 hybrids were indistinguishable from P. angustifolia despite genetic and litter trait differences. (5) Mixed litter packs muted the genetic effects observed in litter packs con- sisting of single genotypes. These results demonstrate that the genetic structure of riparian forests can affect the composition and timing of aquatic insect emergence. Because many riparian trees are clonal, including P. angustifolia, large clone size is likely to result in patches of genetically structured leaf litter that may influence the timing and composition of insect emergence within watersheds. Riparian restoration efforts incorporating different tree genotypes could also influence the biodiversity of emerging aquatic insects. Our work illustrates the importance of plant genes for community and ecosystem processes in riparian corridors
The role of the freshwater shrimp atyaephyra desmarestii in leaf litter breakdown in streams
This version does not correspond to the published one. To access the final version go to: http://www.springerlink.com/content/a31518u452m03286/In aquatic ecosystems, microorganisms and invertebrates provide critical links between plant detritus and higher trophic levels. Atyaephyra desmarestii is an omnivorous decapod that inhabits freshwaters and exhibits high tolerance to temperature oscillations and high ability to colonize new habitats. Although A. desmarestii is able to ingest a variety of foods, few studies have been conducted to elucidate the role of this freshwater shrimp on detritus breakdown in streams. In this study, A. desmarestii was allowed to feed on conditioned or unconditioned alder and eucalyptus leaves in microcosms with or without access to its fecal pellets. At the end of the experiment, total body length of the animals was measured, and the remaining leaves and fecal pellets were used for dry mass quantification and assessment of bacterial and fungal diversity by denaturing gradient gel electrophoresis (DGGE). Cluster analyses of DGGE fingerprints indicated that the major differences in microbial communities on leaves were between leaf types, while on fecal pellets were between conditioned and unconditioned leaves. However, the consumption rate by the shrimp did not differ between leaf types, and was significantly higher on leaves conditioned by microorganisms and in treatments without access to feces. In treatments without access to feces, the production of feces and fine particulate organic matter was also significantly higher for conditioned leaves. Overall, our results support the feeding plasticity of A. desmarestii and its potential role in plant litter breakdown in streams. This might have implications for maintaining stream ecosystem functioning, particularly if more vulnerable shredders decline.The Portuguese Foundation for the
Science and Technology supported S. Duarte (SFRH/BPD/47574/2008
Cell cycle-dependent acetylation of Rb2/p130 in NIH3T3 cells
The retinoblastoma protein (pRb) and the pRb-related proteins, p130 and p107, form the ‘pocket protein' family of cell cycle regulatory factors. A well characterized function of these proteins is the cell cycle-dependent regulation of E2F-responsive genes. The biological activity of pocket proteins is regulated by phosphorylation and for the founding member pRb it has been shown that acetylation also has an important role in modulating its function during the cell cycle. Here, we show that hyperphosphorylated retinoblastoma 2 (Rb2)/p130 also exists in an acetylated form in NIH3T3 cells. Acetylated p130 is present in the nucleus but not in the cytoplasm. Acetylation is cell cycle dependent, starting in S-phase and persisting until late G2-period. Using recombinant p130 and truncated forms for in vitro acetylation by the acetyltransferase p300, we could identify K1079 in the C-terminal part as the major acetylation site by mass spectrometry. Minor acetylation sites were pinpointed to K1068 and K1111 in the C-terminus, and K128 and K130 in the N-terminus. The human papilloma virus 16 protein-E7 preferentially binds to acetylated p130 and significantly increases in vitro p130 acetylation by p300
Callus induction and plant regeneration of tomato (Lycopersicon esculentum cv. IPA 5) via anther culture
Effects of riparian plant diversity loss on aquatic microbial decomposers become more pronounced at longer times
We examined the potential long-term impacts of riparian plant diversity loss on diversity and activity of aquatic microbial decomposers. Microbial assemblages were obtained
in a mixed-forest stream by immersion of mesh bags contain-ing three leaf species (alder, oak and eucalyptus), commonly
found in riparian corridors of Iberian streams. Simulation of
species loss was done in microcosms by including a set of all
leaf species, retrieved from the stream, and non-colonized
leaves of three, two or one leaf species. Leaves were renewed
every month throughout six months, and microbial inoculum
was ensured by a set of colonized leaves from the previous
month. Microbial diversity, leaf mass loss and fungal biomass
were assessed at the second and sixth months after plant
species loss. Molecular diversity of fungi and bacteria, as the
total number of operational taxonomic units per leaf diversity
treatment, decreased with leaf diversity loss. Fungal biomass
tended to decrease linearly with leaf species loss on oak and
eucalyptus, suggesting more pronounced effects of leaf diver-sity on lower quality leaves. Decomposition of alder and
eucalyptus leaves was affected by leaf species identity, mainly
after longer times following diversity loss. Leaf decomposi-tion of alder decreased when mixed with eucalyptus, while
decomposition of eucalyptus decreased in mixtures with oak.
Results suggest that the effects of leaf diversity on microbial
decomposers depended on leaf species number and also on
which species were lost from the system, especially after
longer times. This may have implications for the management
of riparian forests to maintain stream ecosystem functioning.FEDER-POFC-COMPETE and the Portuguese
Foundation for Science and Technology supported this study (PEst-C/
BIA/UI4050/2011, PTDC/AAC-AMB/113746/2009 and PTDC/AAC-AMB/117068/2010), S. Duarte (SFRH/BPD/47574/2008) and I.
Fernandes (SFRH/BD/42215/2007)
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