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1. The FMRF-NH2 gated sodium channel of Biomphalaria glabrata: Localization and expression following infection by Schistosoma mansoni

   https://doi.org/10.1371/journal.pntd.0011249  

   Vicente-Rodríguez, Laura C.; Torres-Arroyo, Amanda C.; Hernández-Vázquez, Anthony; Rosa-Casillas, Mariela; Bracho-Rincón, Dina P.; de Jesús, Paola Méndez; Behra, Martine L.; Habib, Mohamed R.; Zhou, Xiao-Nong; Rosenthal, Joshua J.; et al (June 2023, PLOS Neglected Tropical Diseases)

   Cwiklinski, Krystyna (Ed.)

   The neglected tropical disease schistosomiasis impacts over 700 million people globally. Schistosoma mansoni , the trematode parasite that causes the most common type of schistosomiasis, requires planorbid pond snails of the genus Biomphalaria to support its larval development and transformation to the cercarial form that can infect humans. A greater understanding of neural signaling systems that are specific to the Biomphalaria intermediate host could lead to novel strategies for parasite or snail control. This study examined a Biomphalaria glabrata neural channel that is gated by the neuropeptide FMRF-NH 2 . The Biomphalaria glabrata FMRF-NH 2 gated sodium channel ( Bgl- FaNaC) amino acid sequence was highly conserved with FaNaCs found in related gastropods, especially the planorbid Planorbella trivolvis (91% sequence identity). In common with the P . trivolvis FaNaC, the B . glabrata channel exhibited a low affinity (EC 50 : 3 x 10 −4 M) and high specificity for the FMRF-NH 2 agonist. Its expression in the central nervous system, detected with immunohistochemistry and in situ hybridization, was widespread, with the protein localized mainly to neuronal fibers and the mRNA confined to cell bodies. Colocalization of the Bgl- FaNaC message with its FMRF-NH 2 agonist precursor occurred in some neurons associated with male mating behavior. At the mRNA level, Bgl- FaNaC expression was decreased at 20 and 35 days post infection (dpi) by S . mansoni . Increased expression of the transcript encoding the FMRF-NH 2 agonist at 35 dpi was proposed to reflect a compensatory response to decreased receptor levels. Altered FMRF-NH 2 signaling could be vital for parasite proliferation in its intermediate host and may therefore present innovative opportunities for snail control. 

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2. Capacity for increased surface area in the hydrophobic core of β ‐sheet peptide bilayer nanoribbons

   https://doi.org/10.1002/psc.3334  

   Jones, Christopher W.; Morales, Crystal G.; Eltiste, Sharon L.; Yanchik‐Slade, Francine E.; Lee, Naomi R.; Nilsson, Bradley L. (June 2021, Journal of Peptide Science)

   Amphipathic peptides with amino acids arranged in alternating patterns of hydrophobic and hydrophilic residues efficiently self‐assemble intoβ‐sheet bilayer nanoribbons. Hydrophobic side chain functionality is effectively buried in the interior of the putative bilayer of these nanoribbons. This study investigates consequences on self‐assembly of increasing the surface area of aromatic side chain groups that reside in the hydrophobic core of nanoribbons derived from Ac‐(XKXE)₂‐NH₂peptides (X = hydrophobic residue). A series of Ac‐(XKXE)₂‐NH₂peptides incorporating aromatic amino acids of increasing molecular volume and steric profile (X = phenylalanine [Phe], homophenylalanine [Hph], tryptophan [Trp], 1‐naphthylalanine [1‐Nal], 2‐naphthylalanine [2‐Nal], or biphenylalanine [Bip]) were assessed to determine substitution effects on self‐assembly propensity and on morphology of the resulting nanoribbon structures. Additional studies were conducted to determine the effects of incorporating amino acids of differing steric profile in the hydrophobic core (Ac‐X₁KFEFKFE‐NH₂and Ac‐(X_1,5KFE)‐NH₂peptides, X = Trp or Bip). Spectroscopic analysis by circular dichroism (CD) and Fourier transform infrared (FT‐IR) spectroscopy indicatedβ‐sheet formation for all variants. Self‐assembly rate increased with peptide hydrophobicity; increased molecular volume of the hydrophobic side chain groups did not appear to induce kinetic penalties on self‐assembly rates. Transmission electron microscopy (TEM) imaging indicated variation in fibril morphology as a function of amino acid in the X positions. This study confirms that hydrophobicity of amphipathic Ac‐(XKXE)₂‐NH₂peptides correlates to self‐assembly propensity and that the hydrophobic core of the resulting nanoribbon bilayers has a significant capacity to accommodate sterically demanding functional groups. These findings provide insight that may be used to guide the exploitation of self‐assembled amphipathic peptides as functional biomaterials. 

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3. Variability of biological traits of Bulinus truncatus and Biomphalaria pfeifferi, the intermediate host snails of schistosomiasis, from three climatic zones of Côte d’Ivoire

   https://doi.org/10.3389/fenvs.2023.1193239  

   Diakité, Nana R; Koffi, Patricia B; Konan, Cyrille K; Bassa, Fidèle K; Chamberlin, Andrew J; Ouattara, Mamadou; De_Leo, Giulio A; N’Goran, Eliezer K (December 2023, Frontiers in Environmental Science)

   Background:Schistosomiasis is endemic throughout all regions of Côte d’Ivoire, however, species of the intermediate snail host vary across bioclimatic zones. Hence, a deeper knowledge of the influence of climatic on the life history traits of the intermediate snail host is crucial to understand the environmental determinants of schistosomiasis in a rapidly changing climate. The aim of this study was to run a common garden experiment to assess differences in survival, somatic growth and fecundity of bothBulinus truncatusandBiomphalaria pfeifferisnails collected in three different bioclimatic areas. Methods:A cross-sectional malacological survey was conducted in February 2021 in the south, center and north of Côte d’Ivoire. We sampled two populations ofB. truncatus, the intermediate host snail ofSchistosoma haematobium, from northern and central Côte d’Ivoire, and two populations ofBi.pfeifferi, the intermediate host snail forSchistosoma mansoni, from the southern and central regions. Snails collected at the human-water contact sites were brought in the laboratory where they reproduced. The first generation snails (G₁) for each population were reared under the same laboratory conditions, i.e., at 24°C–26°C, during 63 days (9 weeks), to estimate survival, growth, and fecundity. Results:We found that G₁Bulinussnails from the north population showed higher survival and growth rates during our study and higher number of eggs at first reproduction, compared to the ones from the central region. ForBi.pfeifferi, no significant difference in survival rate was observed between G₁snails from the southern and central populations, whereas those from the south exhibited higher growth rates and higher number of eggs per individual at first reproduction than G₁snails from the central population. Conclusion:Our study provides evidence for heterogeneity in snails’ life-history traits in response to temperature among the populations from the three climatic regions. Further experiments from multiple populations are needed to confirm that snails express traits under optimal conditions, can lead to expansion of their geographical range and hence an increase in the risk of schistosomiasis transmission. Transplantation experiments will be required to assess implications of the changing climate on snails persistence, distribution and abundance. 

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4. Interventions can shift the thermal optimum for parasitic disease transmission

   https://doi.org/10.1073/pnas.2017537118  

   Nguyen, Karena H.; Boersch-Supan, Philipp H.; Hartman, Rachel B.; Mendiola, Sandra Y.; Harwood, Valerie J.; Civitello, David J.; Rohr, Jason R. (March 2021, Proceedings of the National Academy of Sciences)

   Temperature constrains the transmission of many pathogens. Interventions that target temperature-sensitive life stages, such as vector control measures that kill intermediate hosts, could shift the thermal optimum of transmission, thereby altering seasonal disease dynamics and rendering interventions less effective at certain times of the year and with global climate change. To test these hypotheses, we integrated an epidemiological model of schistosomiasis with empirically determined temperature-dependent traits of the human parasiteSchistosoma mansoniand its intermediate snail host (Biomphalariaspp.). We show that transmission risk peaks at 21.7 °C (T_opt), and simulated interventions targeting snails and free-living parasite larvae increasedT_optby up to 1.3 °C because intervention-related mortality overrode thermal constraints on transmission. ThisT_optshift suggests that snail control is more effective at lower temperatures, and global climate change will increase schistosomiasis risk in regions that move closer toT_opt. Considering regional transmission phenologies and timing of interventions when local conditions approachT_optwill maximize human health outcomes. 

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5. Short macrocyclic peptides in sponge genomes

   https://doi.org/10.1073/pnas.2314383121  

   Lin, Zhenjian; Agarwal, Vinayak; Cong, Ying; Pomponi, Shirley A.; Schmidt, Eric W. (March 2024, Proceedings of the National Academy of Sciences)

   Sponges (Porifera) contain many peptide-specialized metabolites with potent biological activities and significant roles in shaping marine ecology. It is well established that symbiotic bacteria produce bioactive “sponge” peptides, both on the ribosome (RiPPs) and nonribosomally. Here, we demonstrate that sponges themselves also produce many bioactive macrocyclic peptides, such as phakellistatins and related proline-rich macrocyclic peptides (PRMPs). Using theStylissa carterisponge transcriptome, methods were developed to find sequences encoding 46 distinct RiPP-type core peptides, of which ten encoded previously identified PRMP sequences. With this basis set, the genome and transcriptome of the spongeAxinella corrugatawas interrogated to find 35 PRMP precursor peptides encoding 31 unique core peptide sequences. At least 11 of these produced cyclic peptides that were present in the sponge and could be characterized by mass spectrometry, including stylissamides A-D and seven previously undescribed compounds. Precursor peptides were encoded in theA. corrugatagenome, confirming their animal origin. The peptides contained signal peptide sequences and highly repetitive recognition sequence-core peptide elements with up to 25 PRMP copies in a single precursor. In comparison to sponges without PRMPs, PRMP sponges are incredibly enriched in potentially secreted polypeptides, with >23,000 individual signal peptide encoding genes found in a single transcriptome. The similarities between PRMP biosynthetic genes and neuropeptides in terms of their biosynthetic logic suggest a fundamental biology linked to circular peptides, possibly indicating a widespread and underappreciated diversity of signaling peptide post-translational modifications across the animal kingdom. 

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