Molecular and biophysical features of hippocampal “lipid rafts aging” are modified by dietary n-3 long-chain polyunsaturated fatty acids

“Lipid raft aging” in nerve cells represents an early event in the development of aging-related neurodegenerative diseases, such as Alzheimer's disease. Lipid rafts are key elements in synaptic plasticity, and their modification with aging alters interactions and distribution of signaling molecules, such as glutamate receptors and ion channels involved in memory formation, eventually leading to cognitive decline. In the present study, we have analyzed, in vivo, the effects of dietary supplementation of n-3 LCPUFA on the lipid structure, membrane microviscosity, domain organization, and partitioning of ionotropic and metabotropic glutamate receptors in hippocampal lipid raffs in female mice. The results revealed several lipid signatures of “lipid rafts aging” in old mice fed control diets, consisting in depletion of n-3 LCPUFA, membrane unsaturation, along with increased levels of saturates, plasmalogens, and sterol esters, as well as altered lipid relevant indexes. These changes were paralleled by increased microviscosity and changes in the raft/non-raft (R/NR) distribution of AMPA-R and mGluR5. Administration of the n-3 LCPUFA diet caused the partial reversion of fatty acid alterations found in aged mice and returned membrane microviscosity to values found in young animals. Paralleling these findings, lipid rafts accumulated mGluR5, NMDA-R, and ASIC2, and increased their R/NR proportions, which collectively indicate changes in synaptic plasticity. Unexpectedly, this diet also modified the lipidome and dimension of lipid rafts, as well as the domain redistribution of glutamate receptors and acid-sensing ion channels involved in hippocampal synaptic plasticity, likely modulating functionality of lipid rafts in memory formation and reluctance to age-associated cognitive decline.     

Distribution of goblet and endocrine cells in the intestine: A comparative study in Amazonian freshwater Tambaqui and hybrid catfish

Goblet cells (GCs) and endocrine cells (ECs) play an important role in intestine physiology, and few studies currently exist for Amazonian fishes. This study aimed to quantify the distribution of GCs and ECs producing cholecystokinin-8 and neuropeptide Y, assessed by mucin histochemistry and peptides immunohistochemistry, in the intestine of two Amazonian species with different feeding habits Tambaqui (Colossosoma macropomum) and hybrid catfish (Pseudoplatystoma reticulatum × Leiarius marmoratus), an omnivore and carnivore, respectively. A systematic literature review correlating feeding habit and GC and EC distribution was also included to contribute to the comparative study. The results of this study provided novel information about the gut cells of Tambaqui and hybrid catfish. Both, GCs and ECs can be found sweeping the entire intestine of Tambaqui and hybrid catfish although the cells can be more concentrated in certain segments. The GCs and ECs in Tambaqui were more uniformly distributed in the midgut segments (T1, T2, and T3). Unlike, in hybrid catfish GCs were more concentrated in the hindgut (C4) and ECs mainly in the two midgut segments (C1 and C2) of hybrid catfish. Based on the comparison between Tambaqui, hybrid catfish, and other fishes in the literature review, we suggest that cell distribution can be partially explained by feeding habits, carnivorous vs. omnivorous.     

Role of saprophagous fly biodiversity in ecological processes and urban ecosystem services

1. Direct consumption of organic matter by the saprophagous larvae provides the ecosystem with a fundamental service by recycling nutrients and reducing exposure to decomposing matter. The present study aimed to assess the functional role of saprophagous flies in the mass loss of different types of decomposing organic matter. 2. Two types of common urban waste were used to measure the role of flies in reducing organic matter: chicken viscera (chicken) and a mixture of flour and uncooked eggs (flour and eggs), representing leftover food. Ten traps baited with each substrate, under field conditions, allowed fly access (exposed to flies) and three traps from each substrate did not (unexposed controls); adult flies entering the traps or emerging from the substrates and substrate mass loss were recorded. 3. Species from Calliphoridae, Sarcophagidae, Muscidae, and Fanniidae families were collected mainly in traps baited with chicken, with Phoridae being the most abundant in traps with flour and eggs as bait. A significantly richer (P < 0.05) assemblage of fly species accessed the traps baited with chicken viscera (21 species) compared with those emerging (11 species), whereas similar numbers of species accessed (n = 5) or emerged (n = 1) from traps baited with flour and eggs (average richness accessing 7.97, emerging 2.83). Chicken substrate mass loss and species richness were positively related (r = 0.56, P = 0.001). In traps where richness was larger than 10 species, the substrates were reduced by more than 85% of their initial weight compared with unexposed controls, which lost 30%. Substrate mass loss significantly increased with the abundance of flies (r = 0.73, P < 0.0001). 4. The results of the present study support the functional role of saprophagous species diversity on the decomposition rates of organic matter, reinforcing the negative consequences of loss or gain of species in modified landscapes and for ecosystem function.     

First genetic record of the non-native muzzled blenny Omobranchus punctatus (Teleostei: Blenniidae) in the Atlantic Coast of Central and South America

In this study we sequenced two mitochondrial (COI and 16S rRNA) and one nuclear (18S rRNA) gene fragment of an introduced muzzled blenny (Omobranchus punctatus) specimen collected from the Orinoco Delta (Gulf of Paria estuary) in Venezuela. This is the first genetic data generated for this species' introduced range in Central and South America, suggesting an introduction from the Indian Ocean.     

Suppression of a BAHD acyltransferase decreases p-coumaroyl on arabinoxylan and improves biomass digestibility in the model grass Setaria viridis

Grass cell walls have hydroxycinnamic acids attached to arabinosyl residues of arabinoxylan (AX), and certain BAHD acyltransferases are involved in their addition. In this study, we characterized one of these BAHD genes in the cell wall of the model grass Setaria viridis. RNAi silenced lines of S. viridis (SvBAHD05) presented a decrease of up to 42% of ester-linked p-coumarate (pCA) and 50% of pCA-arabinofuranosyl, across three generations. Biomass from SvBAHD05 silenced plants exhibited up to 32% increase in biomass saccharification after acid pre-treatment, with no change in total lignin. Molecular dynamics simulations suggested that SvBAHD05 is a p-coumaroyl coenzyme A transferase (PAT) mainly involved in the addition of pCA to the arabinofuranosyl residues of AX in Setaria. Thus, our results provide evidence of p-coumaroylation of AX promoted by SvBAHD05 acyltransferase in the cell wall of the model grass S. viridis. Furthermore, SvBAHD05 is a promising biotechnological target to engineer crops for improved biomass digestibility for biofuels, biorefineries and animal feeding.