Use of low dosage amino acid blends to prevent stress-related piglet diarrhea

Weaning is a challenging period for piglets associated with reduced feed intake, impairment of gut integrity, and diarrhea. Previous studies demonstrate that supplementation with single functional amino acids promote piglets’ performance due to the improvement of intestinal health. Thus, we hypothesized that a combination of functional amino acids provided beyond the postulated requirement for growth could facilitate the weaning transition. Ninety piglets, initially stressed after weaning by 100 min overland transport, received a control diet or the same diet supplemented with a low-dosed (0.3 %) mixture of amino acids (AAB-1: L-arginine, L-leucine, L-valine, L-isoleucine, L-cystine; AAB-2: L-arginine, L-leucine, L-valine, L-isoleucine, L-cystine, L-tryptophan) for 28 days. Fecal consistency was ranked daily, growth performance was assessed weekly. On day 1 and 14 of the trial, blood samples were collected from a subset of 10 piglets per group to assess concentrations of insulin-like growth factor 1. After 28 days of feeding, tissues were obtained from the same piglets to analyze gut morphology and relative mRNA expression of genes related to gut function. Even if the stress response as indicated by rectal temperature was not different between the groups, pigs supplemented with AAB-2 showed firmer feces after weaning and less days with diarrhea compared to control. Furthermore, the jejunal expression of the MUC-2 gene was reduced (P < 0.05) in group AAB-2. Both amino acid mixtures increased crypt depth in the duodenum. Collectively, the given results indicate that 0.3 % extra amino acid supplementation might alleviate post-weaning diarrhea but did not alter growth performance of weanling piglets.

Plasmodium falciparum histidine-rich protein 2 (PfHRP2) diversity in Ghana

Background: In the absence of microscopy, Plasmodium falciparum histidine-rich proteins 2 (PfHRP2)-based rapid diagnostic tests (RDTs) are recommended for the diagnosis of falciparum malaria, particularly in endemic regions. However, genetic variability of the PfHRP2 gene threatens the usefulness of the test. This study aimed to investigate the diversity of PfHRP2 in malaria cases among children in Ghana.Methods: A cross-sectional study was conducted at the Adidome Government Hospital in the Volta Region of Ghana. A total of 50 children with mean age of 6.6±3.5 years and diagnosed of falciparum malaria were included. Blood samples were collected for complete blood count, malaria parasite identification and counting. DNA samples were amplified and sequenced. Nucleotide sequences were translated in silico to corresponding amino acids and the deduced amino acids sequences were analyzed for diversity.Results: The number of repeats and number of each repeat within PfHRP2 varied between isolates. Twelve rare PfHRP2 repeat types, two of which are previously unreported, were identified in this study. Our HRP2 sequence shared high similarity with isolates from Kenya. Using Baker’s regression model, Group B was the highest occurring type (58.0%). Screening of all sequences for epitopes recognized by PfHRP2-specific monoclonal antibodies (mAbs), we found the predominant motif to be AHHAADAHH, which is recognized by the C1-13 mAbs.Conclusion: This study reports diversity of P. falciparum histidine-rich proteins 2 in samples from Ghanaian children with symptomatic malaria. We highlight the existence of extra amino acid repeat types which adds to the PfHRP2 antigenic variability. The findings of this study will contribute to the understanding of the performance of PfHRP2-based RDTs in the Ghanaian setting.

Nisin J, a Novel Natural Nisin Variant, Is Produced by Staphylococcus capitis Sourced from the Human Skin Microbiota

ABSTRACT The skin microbiota is thought to play a key role in host protection from infection. Nisin J is a novel nisin variant produced by Staphylococcus capitis APC 2923, a strain isolated from the toe web space area in a screening study performed on the human skin microbiota. Whole-genome sequencing and mass spectrometry of the purified peptide confirmed that S. capitis APC 2923 produces a 3,458-Da bacteriocin, designated nisin J, which exhibited antimicrobial activity against a range of Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and Cutibacterium acnes. The gene order in the nisin J gene cluster (nsjFEGBTCJP) differs from that of other nisin variants in that it is lacking the nisin regulatory genes, nisRK, as well as the nisin immunity gene nisI. Nisin J has 9 amino acid changes compared to prototypical nisin A, with 8 amino acid substitutions, 6 of which are not present in other nisin variants (Ile4Lys, Met17Gln, Gly18Thr, Asn20Phe, Met21Ala, Ile30Gly, Val33His, and Lys34Thr), and an extra amino acid close to the C terminus, rendering nisin J the only nisin variant to contain 35 amino acids. This is the first report of a nisin variant produced by a Staphylococcus species and the first nisin producer isolated from human skin. IMPORTANCE This study describes the characterization of nisin J, the first example of a natural nisin variant, produced by a human skin isolate of staphylococcal origin. Nisin J displays inhibitory activity against a wide range of bacterial targets, including MRSA. This work demonstrates the potential of human commensals as a source for novel antimicrobials that could form part of the solution to antibiotic resistance across a broad range of bacterial pathogens.

Characterization of Amm VIII from Androctonus mauretanicus mauretanicus: a new scorpion toxin that discriminates between neuronal and skeletal sodium channels

The venom of the scorpion Androctonus mauretanicus mauretanicus was screened by use of a specific serum directed against AaH II, the scorpion α-toxin of reference, with the aim of identifying new analogues. This led to the isolation of Amm VIII (7382.57 Da), which gave a highly positive response in ELISA, but was totally devoid of toxicity when injected subcutaneously into mice. In voltage-clamp experiments with rat brain type II Na+ channel rNav1.2 or rat skeletal muscle Na+ channel rNav1.4, expressed in Xenopus oocytes, the EC50 values of the toxin-induced slowing of inactivation were: 29±5 and 416±14 nM respectively for AmmVIII and 2.6±0.3 nM and 2.2±0.2 nM, respectively, for AaH II interactions. Accordingly, Amm VIII clearly discriminates neuronal versus muscular Na+ channel. The Amm VIII cDNA was amplified from a venom gland cDNA library and its oligonucleotide sequence determined. It shows 87% sequence homology with AaH II, but carries an unusual extension at its C-terminal end, consisting of an additional Asp due to a point mutation in the cDNA penultimate codon. We hypothesized that this extra amino acid residue could induce steric hindrance and dramatically reduce recognition of the target by Amm VIII. We constructed a model of Amm VIII based on the X-ray structure of AaH II to clarify this point. Molecular modelling showed that this C-terminal extension does not lead to an overall conformational change in Amm VIII, but drastically modifies the charge repartition and, consequently, the electrostatic dipole moment of the molecule. At last, liquid-phase radioimmunassays with poly- and monoclonal anti-(AaH II) antibodies showed the loss of conformational epitopes between AaH II and Amm VIII.

A water channel of the nematode C. elegans and its implications for channel selectivity of MIP proteins

A genome project focusing on the nematode Caenorhabditis elegans has demonstrated the presence of eight cDNAs belonging to the major intrinsic protein superfamily. We functionally characterized one of these cDNAs named C01G6.1. Injection of C01G6.1 cRNA increased the osmotic water permeability ( P f) of Xenopusoocytes 11-fold and the urea permeability 4.5-fold but failed to increase the glycerol permeability. It has been speculated that the MIP family may be separated into two large subfamilies based on the presence or absence of two segments of extra amino acid residues (∼15 amino acids) at the second and third extracellular loops. Because C01G6.1 (designated AQP-CE1), AQP3, and glycerol facilitator (GlpF) all have these two segments, we replaced the segments of AQP-CE1 with those of AQP3 and GlpF to identify their roles. The functional characteristics of these mutants were principally similar to that of wild-type AQP-CE1, although the values of P f and urea permeability were decreased by 39–74% and 28–65%, respectively. These results suggest that the two segments of extra amino acid residues may not contribute to channel selectivity or formation of the route for small solutes.

Phosphoglucomutase 1: a gene with two promoters and a duplicated first exon

In view of its central role in glycolysis and gluconeogenesis and its polymorphic genetic variability, the phosphoglucomutase 1 (PGM1) gene in man has been the target of protein structural studies and genetic analysis for more than 25 years. We have now isolated genomic clones containing the complete PGM1 gene and have shown that it spans over 65 kb and contains 11 exons. We have also shown that the sites of the two mutations which form the molecular basis for the common PGM1 protein polymorphism lie in exons 4 and 8 and are 18 kb apart. Within this region there is a site of intragenic recombination. We have discovered two alternatively spliced first exons, one of which, exon 1A, is transcribed in a wide variety of cell types; the other, exon 1B, is transcribed in fast muscle. Exon 1A is transcribed from a promoter which has the structural hallmarks of a housekeeping promoter but lies more than 35 kb upstream of exon 2. Exon 1B lies 6 kb upstream of exon 2 within the large first intron of the ubiquitously expressed PGM1 transcript. The fast-muscle form of PGM1 is characterized by 18 extra amino acid residues at its N-terminal end. Sequence comparisons show that exons 1A and 1B are structurally related and have arisen by duplication.