Irrelevant features of a stimulus can either facilitate or disrupt performance in a working memory task: the role of fluid intelligence

It has been shown that fluid intelligence (gf) is fundamental to overcome interference due to information of a previously encoded item along a task-relevant domain. However, the biasing effect of task-irrelevant dimensions is still unclear as well as its relation with gf. The present study aimed at clarifying these issues. Gf was assessed in 60 healthy subjects. In a different session, the same subjects performed two versions (letter-detection and spatial) of a three-back working memory task with a set of physically identical stimuli (letters) presented at different locations on the screen. In the letter-detection task, volunteers were asked to match stimuli on the basis of their identity whereas, in the spatial task, they were required to match items on their locations. Cross-domain bias was manipulated by pseudorandomly inserting a match between the current and the three back items on the irrelevant domain. Our findings showed that a task-irrelevant feature of a salient stimulus can actually bias the ongoing performance. We revealed that, at trials in which the current and the three-back items matched on the irrelevant domain, group accuracy was lower (interference). On the other hand, at trials in which the two items matched on both the relevant and irrelevant domains, the group showed an enhancement of the performance (facilitation). Furthermore, we demonstrated that individual differences in fluid intelligence covaries with the ability to override cross-domain interference in that higher gf subjects showed better performance at interference trials than low gf subjects. Altogether, our findings suggest that stimulus features irrelevant to the task can affect cognitive performance along the relevant domain and that gf plays an important role in protecting relevant memory contents from the hampering effect of such a bias.     

Changes in the tobacco leaf apoplast proteome in response to salt stress

The apoplast of plant cells is a dynamic compartment involved in many processes, including maintenance of tissue shape, development, nutrition, signalling, detoxification and defence. In this work we used Nicotiana tabacum plants as a model to investigate changes in the soluble apoplast composition induced in response to salt stress. Apoplastic fluid was extracted from leaves of control plants and plants exposed to salt stress, using a vacuum infiltration procedure. Two-dimension electrophoretic analyses revealed about 150 polypeptide spots in the pH range of 3.0 to 10.0, in independent protein extracts, with a high level of reproducibility between the two sample sets. Quantitative evaluation and statistical analyses of the resolved spots in treated and untreated samples revealed 20 polypeptides whose abundance changed in response to salt stress. Mass spectroscopic peptide separation and sequencing was used to identify polypeptides affected by salt stress. While the levels of some proteins were reduced by salt-treatment, an enhanced accumulation of protein species known to be induced by biotic and abiotic stresses was observed. In particular, two chitinases and a germin-like protein increased significantly and two lipid transfer proteins were expressed entirely de novo. Some apoplastic polypeptides, involved in cell wall modifications during plant development, remained largely unchanged. The significance of these components is discussed in the context of stress responses in plants.     

Neisseria meningitidis NadA is a new invasin which promotes bacterial adhesion to and penetration into human epithelial cells

Neisseria meningitidis is a human pathogen, which is a major cause of sepsis and meningitis. The bacterium colonizes the upper respiratory tract of approximately 10% of humans where it lives as a commensal. On rare occasions, it crosses the epithelium and reaches the bloodstream causing sepsis. From the bloodstream it translocates the blood-brain barrier, causing meningitis. Although all strains have the potential to cause disease, a subset of them, which belongs to hypervirulent lineages, causes disease more frequently than others. Recently, we described NadA, a novel antigen of N. meningitidis, present in three of the four known hypervirulent lineages. Here we show that NadA is a novel bacterial invasin which, when expressed on the surface of Escherichia coli, promotes adhesion to and invasion into Chang epithelial cells. Deletion of the N-terminal globular domain of recombinant NadA or pronase treatment of human cells abrogated the adhesive phenotype. A hypervirulent strain of N. meningitidis where the nad A gene was inactivated had a reduced ability to adhere to and invade into epithelial cells in vitro. NadA is likely to improve the fitness of N. meningitidis contributing to the increased virulence of strains that belong to the hypervirulent lineages.     

Recombineering BAC transgenes for protein tagging

Protein tagging offers many advantages for proteomic and regulomic research, particularly due to the use of generic and highly sensitive methods that can be applied with reasonable throughput. Ideally, protein tagging is equivalent to having a high affinity antibody for every chosen protein. However, these advantages are compromised if the tagged protein is overexpressed, which is usually the case from cDNA expression vectors. BAC (bacterial artificial chromosome) transgenes present a way to express a chosen protein at physiological levels with all regulatory elements in their native configurations, including cell cycle, alternative splicing and microRNA regulation. Recombineering has become the method of choice for modifying large constructs like BACs. Here, we present a method for protein tagging by recombineering BACs, transfecting cells and evaluating tagged protein expression.     

Therapeutic treatment with scFv–PLGA nanoparticles decreases pulmonary fungal load in a murine model of paracoccidioidomycosis

Paracoccidioidomycosis (PCM) is a systemic mycosis with lymphatic dissemination that is caused by Paracoccidioides species. Treatment of PCM consists of chemotherapeutics such as itraconazole, trimethoprim, sulfamethoxazole or amphotericin B. However, several studies are aiming to develop therapeutic alternatives for the treatment of fungal infection using new molecules as adjuvants. The single-chain variable fragments (scFv) from an antibody that mimics the main fungal component incorporated within poly(lactide-co-glycolic) acid (PLGA) nanoparticles helped treat the fungal disease. After expressing the scFv in Picchia pastoris (P. pastoris), the recombinant molecules were coupled with PLGA, and the BALB/c mice were immunized before or after infection with yeast Paracoccidioides brasiliensis (P. brasiliensis). Our results showed decreased disease progression and decreased fungal burden. Taken together, our results showed an increased of IFN-γ and IL-12 cytokine production and an increased number of macrophages and dendritic cells in the pulmonary tissue of BALB/c mice treated with a high concentration of our molecule. Our data further confirm that the scFv plays an important role in the treatment of experimental PCM.     

Responses of seed of Stylosanthes humilis to germination regulators

Seed of Stlosanthes humilis both have hard integuments and display physiological dormancy, the latter being lost during post-harvest ageing. Ethrel and l-aminocyclopropane-1-carboxylic acid (ACC) partially released scarified young seed from physiological dormancy. Cobalt and silver ions and abscisic acid inhibited germination of scarified non-dormant seed. Abscisic acid also inhibited germination of voung seed promoted by ACC. Thiourea and ethrel plus benzyladenine showed the greatest efficacy in breaking seed dormancy.     

Different temperature perception in high‐elevation plants: new insight into phenological development and implications for climate change in the alpine tundra

In alpine habitats, predicted warmer and longer growing seasons will influence plant phenology, with important implications for species adaptation and vegetation dynamics. However, little is known on the temperature sensitivity of different phenophases and on the characteristics allowing phenological variation among and within species. By integrating interannual micro‐climatic variability with experimental warming, we explored how the phenology of three alpine species is influenced by temperature and what mechanisms underlie intra‐ and inter‐specific phenological differences. The present study demonstrated that alpine plants have different temperature responses during their reproductive cycle, do not have constant thermal thresholds and heat‐use efficiencies to achieve the seed dispersal stage and can change their temperature sensitivity to flower along snowmelt gradients. In addition, the length of the reproductive cycle, which proved to be species‐specific under experimental warming, does not seem to be the only life‐history trait under selective pressure due to the short‐length of the snow‐free period. In a warming climate scenario, the phenology of sexual reproduction will be considerably altered, and alpine plants may be subjected to changes in population dynamics driven by altered perception of environmental cues appropriate for coordinating the timing of key life‐history events.     

Propulsion Phase of the Single Leg Triple Hop Test in Women with Patellofemoral Pain Syndrome: A Biomechanical Study

Asymmetry in the alignment of the lower limbs during weight-bearing activities is associated with patellofemoral pain syndrome (PFPS), caused by an increase in patellofemoral (PF) joint stress. High neuromuscular demands are placed on the lower limb during the propulsion phase of the single leg triple hop test (SLTHT), which may influence biomechanical behavior. The aim of the present cross-sectional study was to compare kinematic, kinetic and muscle activity in the trunk and lower limb during propulsion in the SLTHT using women with PFPS and pain free controls. The following measurements were made using 20 women with PFPS and 20 controls during propulsion in the SLTHT: kinematics of the trunk, pelvis, hip, and knee; kinetics of the hip, knee and ankle; and muscle activation of the gluteus maximus (GM), gluteus medius (GMed), biceps femoris (BF) and vastus lateralis (VL). Differences between groups were calculated using three separate sets of multivariate analysis of variance for kinematics, kinetics, and electromyographic data. Women with PFPS exhibited ipsilateral trunk lean; greater trunk flexion; greater contralateral pelvic drop; greater hip adduction and internal rotation; greater ankle pronation; greater internal hip abductor and ankle supinator moments; lower internal hip, knee and ankle extensor moments; and greater GM, GMed, BL, and VL muscle activity. The results of the present study are related to abnormal movement patterns in women with PFPS. We speculated that these findings constitute strategies to control a deficient dynamic alignment of the trunk and lower limb and to avoid PF pain. However, the greater BF and VL activity and the extensor pattern found for the hip, knee, and ankle of women with PFPS may contribute to increased PF stress.     

Bird species of black water inundation forests in the Jaú National Park (Amazonas state, Brazil): their contribution to regional species richness

We compared the relative contribution of blackwater inundation forest (igapó) and unflooded (terra firme) forest for regional bird species diversity in the lower Rio Negro region. For analyses of habitat preference we used mist-net samples and an unpublished bird species check-list. The igapó forest had lower bird species diversity than the terra firme forest. However, some 14% of the forest bird species in the region are restricted to igapó forest. Species composition was found to be distinct between the understories of the two forest types. Common forest bird guilds in the Neotropics such as ant-following birds avoid igapó forest. The differential habitat selection among birds in the inundated and unflooded forest is likely to result from vegetation structure and biological interactions such as aggressive behaviour. Since the inundated forest has a typical biota, conservation efforts needs to be directed to protect these habitats. Unfortunately, inundation forests are threatened by several human actions, especially dam construction. The extent of protected areas in the Brazilian Amazon is insufficient for the adequate protection of the inundated habitats, because it includes only 3% of the total area.     

A new species of Tiddergasilus Marques & Boeger, 2018 (Copepoda: Ergasilidae) from the gills of Astyanax lacustris (Lütken) (Osteichthyes: Characidae) in Brazil

A new parasitic copepod, Tiddergasilus bipartitus n. sp. (Copepoda, Ergasilidae), is described herein based on three adult females found attached to the gills of the yellow-tail lambari Astyanax lacustris (Lütken), sampled in Pardo River, municipality of Botucatu, São Paulo State, Brazil. Tiddergasilus bipartitus n. sp. was recognized as a new member of the monotypic genus Tiddergasilus Marques & Boeger, 2018 by having: antennule 6-segmented; maxillary basis armed with 2 terminal teeth and ornamented with multiple spinules; second and third leg both with endopod 3-segmented. The new copepod can be distinguished from its congener, Tiddergasilus iheringi (Tidd, 1942), by the morphology of the antennal claw, number of somites/segments in abdomen and fourth leg, and by the ornamentation of the first leg. This report expands the geographic distribution and diversity of fish species parasitized with Tiddergasilus spp. in Brazil. Moreover, it also represents the first report of an ergasilid species in the Pardo River. A list of diagnostic features for the Brazilian species of Ergasilus von Nordmann, 1832 is provided herein, in order to aid comparisons with the species of this complex genus.