Long-term aquatic biomonitoring in a Southern Brazil urban center: the Guaíba Lake fish community structure through the years

Environmental Biology of Fishes - The ichthyofauna of a large lake located in one of the biggest urban centers in Southern South America was studied for 15 years. Variations in...     

Attachment Strength of Listeria monocytogenes and its Internalin-Negative Mutants

A single cell of Listeria monocytogenes attached on food contact surfaces can be a potential source of cross-contamination in a food-processing plant. To see whether internalin A (InlA) and B (InlB), major surface proteins on L. monocytogenes, play a significant role in the attachment process, wild-type L. monocytogenes EGD (LM_EGD) and its isogenic internalin-negative mutants (LM_EGDΔinlA, LM_EGDΔinlB, and LM_EGDΔinlAB) were used to determine attachment strength on inert glass surface. Western blot analysis using InlA and InlB antibodies confirmed the absence of InlA in LM_EGDΔinlA, InlB in LM_EGDΔinlB, and both InlA and InlB in LM_EGDΔinlAB. Regardless of initial attachment numbers, LM_EGD which expressed both InlA and InlB proteins exhibited the strongest attachment strength while the double mutant (LM_EGDΔinlAB) exhibited the weakest. The two single mutants (LM_EGDΔinlA and LM_EGDΔinlB) that expressed only one type of the internalins were shown to have intermediate attachment strength. These results suggest that both InlA and InlB expression play a significant role in the attachment strength of L. monocytogenes on glass surface.     

Toxicity of rhizomes of the invasive Hedychium coronarium (Zingiberaceae) on aquatic species

The production and release of chemical compounds by invasive plants can affect competitors and native species overall, destabilizing ecological interactions and harming ecosystem functioning. Hedychium coronarium is an invasive macrophyte common on Brazilian riparian areas that produces a wide variety of allelochemicals, but little is known about their effect on aquatic species. Here, we identified the major chemical compounds of the aqueous extract of H. coronarium rhizomes and assessed its toxicity, evaluating the growth inhibition of one alga (Raphidocelis subcapitata) and one macrophyte (Lemna minor), and the lethality of cladoceran (Ceriodaphnia silvestrii and Daphnia similis) and Chironomidae larvae (Chironomus sancticaroli). The majoritarian compounds of H. coronarium rhizomes were Coronarin D and Coronarin D Ethyl Ether. The aqueous extract was toxic for all tested species. We observed growth inhibition in R. subcapitata, as well as reduction in biomass in L. minor. Chironomus sancticaroli and cladoceran were the most sensible species. The aqueous extract of H. coronarium rhizomes was toxic on tested conditions, suggesting that the rhizome compounds may interfere on aquatic organisms and in the dynamic of trophic webs of aquatic ecosystems on invaded areas.

     

Impacto de la actividad física sobre el control metabólico y el desarrollo de complicaciones crónicas en pacientes con diabetes mellitus tipo 1

Together with a balanced diet, regular physical activity is one of the pillars of diabetes mellitus (DM) management. Physical activity theoretically provides the same advantages in people with DM as in the general population and also has some beneficial effects in controlling metabolic factors, such as improving blood glucose levels and insulin sensitivity. In this article, we analyze the main clinical studies published to date that evaluate the impact of physical activity on metabolic control or the development of chronic complications in patients with type 1 diabetes mellitus. In conclusion, most of the evaluated studies show that regular physical activity favorably affects metabolic control in DM (or at least does not have adverse effects). However, there is insufficient information about the impact of physical activity on the development and progression of chronic complications.     

Atlantic Forest topsoil nutrients can be resistant to disturbance and forest clearing

Human impacts can affect the soil properties through erosion and leaching, the ecosystem functions and, consequently, the capacity of a forest to regenerate. Here, we determine the effects of forest disturbance and succession on selected soil chemical properties using two different approaches, before‐after‐control‐impact (BACI) and space‐for‐time (SFT) substitution, and the threatened Atlantic Forest biome as model. We assessed with BACI the long‐term (37‐year) effects of clear cutting on soil properties by comparing data from two topsoil surveys (1978–2017) divided into two treatments: a preserved old growth forest (control) and an adjacent forest that was experimentally cleared with full tree removal (clear‐cut). We examined with SFT the relationship between stand age and soil properties using soil data from three old growth and 13 s growth forests ranging from 7 to 33 years. We found no significant differences between treatments for any soil property or significant changes in phosphorus, potassium, and calcium + magnesium over time. In contrast, pH increased and aluminum decreased in both areas. No relation was found between forest age and most of soil properties, with the exception of potassium which returned to old growth forest levels after 20 years of natural succession, and pH. BACI indicated that deforestation of old growth forest caused no significant effects on soil chemical properties after 37 years of regeneration. SFT demonstrated that soil properties did not change significantly during forest regeneration on formerly disturbed lands. Our findings indicate that natural nutrient‐depleted lowland forests were overall resistant to deforestation followed by passive regeneration at landscape scale. Abstract in Portuguese is available with online material.     

Phylogenetic and gene-centric metagenomics of the canine intestinal microbiome reveals similarities with humans and mice

This study is the first to use a metagenomics approach to characterize the phylogeny and functional capacity of the canine gastrointestinal microbiome. Six healthy adult dogs were used in a crossover design and fed a low-fiber control diet (K9C) or one containing 7.5% beet pulp (K9BP). Pooled fecal DNA samples from each treatment were subjected to 454 pyrosequencing, generating 503 280 (K9C) and 505 061 (K9BP) sequences. Dominant bacterial phyla included the Bacteroidetes/Chlorobi group and Firmicutes, both of which comprised ∼35% of all sequences, followed by Proteobacteria (13–15%) and Fusobacteria (7–8%). K9C had a greater percentage of Bacteroidetes, Fusobacteria and Proteobacteria, whereas K9BP had greater proportions of the Bacteroidetes/Chlorobi group and Firmicutes. Archaea were not altered by diet and represented ∼1% of all sequences. All archaea were members of Crenarchaeota and Euryarchaeota, with methanogens being the most abundant and diverse. Three fungi phylotypes were present in K9C, but none in K9BP. Less than 0.4% of sequences were of viral origin, with >99% of them associated with bacteriophages. Primary functional categories were not significantly affected by diet and were associated with carbohydrates; protein metabolism; DNA metabolism; cofactors, vitamins, prosthetic groups and pigments; amino acids and derivatives; cell wall and capsule; and virulence. Hierarchical clustering of several gastrointestinal metagenomes demonstrated phylogenetic and metabolic similarity between dogs, humans and mice. More research is required to provide deeper coverage of the canine microbiome, evaluate effects of age, genetics or environment on its composition and activity, and identify its role in gastrointestinal disease.     

Heterogeneity of the digestible insoluble fiber of selected forages in situ

Long-term in situ incubations were performed to verify the likelihood of the heterogeneity concept of the potentially digestible fraction of the insoluble fiber (NDFom) by fitting both heterogeneous and homogeneous potentially digestible NDFom versions of a generalized compartmental model of digestion (GCMD). Corn silage and eleven tropical grasses and alfalfa hay were studied. Data were gathered from a study in which forage samples in nylon bags were incubated in rumen cannulated steers so that three profiles per forage were generated. The incubation endpoint was used to form sets of time profiles. The original set consisted of profiles ending at 1440 h, and the other two were formed by using 96 and 240 h as the incubation endpoints, respectively. The indigestible residue was estimated using nonlinear least squares or by assuming it to be 2.4 times lignin determined by the sulphuric acid method (Lignin (sa)). Therefore, eight different models were evaluated by combining end points of digestion, and the homogeneous and heterogeneous versions of GCMD with the two ways of estimating the indigestible residue. The likelihood of the models was assessed by computing Akaike information criteria. The effects of forage, model, and their interaction were analyzed by taking model as a repeated measurement. Heterogeneity of the potentially degradable fraction for NDFom was detected with long-term incubation trials (up to 1440 h) for some forages, and the introduction of the 2.4×Lignin (sa) as a direct measure of the indigestible residue improved the likelihood of the heterogeneous version of GCMD. The forage by model interaction was significant for many comparable parameter estimates, which means that specific and inconsistent results for models within forages were produced depending on the definition of the incubation end-point. The indigestible residue was overestimated with short-term incubation profiles, but the overestimation was lower for the profiles ending at 240 h whether compared to profiles ending at 96 h. Given the likelihood of the heterogeneous version of GCMD fitted to profiles ending at 1440 h and at 240 h for some forages, the heterogeneity concept should be investigated whenever the research interest relies on estimating the kinetic attributes of the degradation profiles of the NDFom in situ.