Sargassum spp. Ethanolic Extract Elicits Toxic Responses and Malformations in Zebrafish (Danio rerio) Embryos.

The amount of Sargassum spp. arriving in the Caribbean Sea has increased steadily in the last few years, producing a profound environmental impact on the ecological dynamics of the coasts of the Yucatan Peninsula. We characterized the toxicological effects of an ethanolic extract of Sargassum spp. on zebrafish (Danio rerio) embryos (ZFEs) in a 96-h static bioassay using T1 (0.01 mg/L), T2 (0.1 mg/L), T3 (1 mg/L), T4 (10 mg/L), T5 (25 mg/L), T6 (50 mg/L), T7 (75 mg/L), T8 (100 mg/L), T9 (200 mg/L), and T10 (400 mg/L). In this extract, we detected 74 compounds by gas chromatography-mass spectrometry (GC-MS), of which hexadecanoic acid methyl ester, and 2-pentanone 4-hydroxy-4-methyl, were the most abundant. In ZFEs, a median lethal concentration of 251 mg/L was estimated. Exposed embryos exhibited extensive morphological changes, including edema in the yolk sac, scoliosis, and loss of pigmentation, as well as malformations of the head, tail, and eyes. By integrating these abnormalities using the Integrated Biological Response (IBRv2) and General Morphological Score (GMS) indices, we were able to determine that ZFEs exposed to 200 mg/L (T9) exhibited the most pronounced biological response in comparison with the other groups. In the comparative transcriptomic analysis, 66 genes were upregulated, and 246 genes were downregulated in the group exposed to 200 mg/L compared with the control group. In the upregulated genes, we identified several gene ontology-enriched terms, such as response to xenobiotic stimuli, cellular response to chemical stimulus, transcriptional regulation, pigment metabolic process, erythrocyte differentiation and embryonic hemopoiesis, extracellular matrix organization, and chondrocyte differentiation involved in endochondral bone morphogenesis, among others. In the down-regulated genes, we found many genes associated with nervous system processes, sensory and visual perception, response to abiotic stimulus, and the nucleoside phosphate biosynthetic process. The probable connections among the morphological changes observed in the transcriptome are thoroughly discussed. Our findings suggest that Sargassum spp. exposure can induce a wide negative impact on zebrafish embryos. Environ Toxicol Chem 2024;43:1075-1089. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Scaffold Hopping to Imidazo[1,2-a]pyrazin-8-one Positive Allosteric Modulators of Metabotropic Glutamate 2 Receptor.

Glutamate hyperfunction is implicated in multiple neurological and psychiatric diseases. Activation of the mGlu2 receptor results in reduced glutamate release and decreased excitability representing a promising novel therapeutic agent for the treatment of disorders such as epilepsy, schizophrenia, mood, anxiety, and other neuropsychiatric disorders. We have previously reported substantial efforts leading to potent and selective mGlu2 PAMs from different chemical series. Herein, the discovery and optimization of a novel series of imidazopyrazinone mGlu2 PAMs are reported. This new scaffold originated from computational searching of fragment databases and comparison with our previously explored scaffolds. Optimization guided by our robust understanding of SAR from former series led to potent, selective, and brain-penetrant compounds.

Diazaspirononane Nonsaccharide Inhibitors of O-GlcNAcase (OGA) for the Treatment of Neurodegenerative Disorders.

O-GlcNAcylation is a post-translational modification of tau understood to lower the speed and yield of its aggregation, a pathological hallmark of Alzheimer's disease (AD). O-GlcNAcase (OGA) is the only enzyme that removes O-linked N-acetyl-d-glucosamine (O-GlcNAc) from target proteins. Therefore, inhibition of OGA represents a potential approach for the treatment of AD by preserving the O-GlcNAcylated tau protein. Herein, we report the multifactorial optimization of high-throughput screening hit 8 to a potent, metabolically stable, and orally bioavailable diazaspirononane OGA inhibitor (+)-56. The human OGA X-ray crystal structure has been recently solved, but bacterial hydrolases are still widely used as structural homologues. For the first time, we reveal how a nonsaccharide series of inhibitors binds bacterial OGA and discuss the suitability of two different bacterial orthologues as surrogates for human OGA. These breakthroughs enabled structure-activity relationships to be understood and provided context and boundaries for the optimization of druglike properties.

Virtual screening of approved drugs as potential SARS-CoV-2 main protease inhibitors.

The global emergency caused by COVID-19 makes the discovery of drugs capable of inhibiting SARS-CoV-2 a priority, to reduce the mortality and morbidity of this disease. Repurposing approved drugs can provide therapeutic alternatives that promise rapid and ample coverage because they have a documented safety record, as well as infrastructure for large-scale production. The main protease of SARS-CoV-2 (Mpro) is an excellent therapeutic target because it is critical for viral replication; however, Mpro has a highly flexible active site that must be considered when performing computer-assisted drug discovery. In this work, potential inhibitors of the main protease (Mpro) of SARS-Cov-2 were identified through a docking-assisted virtual screening procedure. A total of 4384 drugs, all approved for human use, were screened against three conformers of Mpro. The ligands were further studied through molecular dynamics simulations and binding free energy analysis. A total of nine currently approved molecules are proposed as potential inhibitors of SARS-CoV-2. These molecules can be further tested to speed the development of therapeutics against COVID-19.

A Glycosaminoglycan-Rich Fraction from Sea Cucumber Isostichopus badionotus Has Potent Anti-Inflammatory Properties In Vitro and In Vivo.

Sea cucumber body wall contains several naturally occurring bioactive components that possess health-promoting properties. Isostichopus badionotus from Yucatan, Mexico is heavily fished, but little is known about its bioactive constituents. We previously established that I. badionotus meal had potent anti-inflammatory properties in vivo. We have now screened some of its constituents for anti-inflammatory activity in vitro. Glycosaminoglycan and soluble protein preparations reduced 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammatory responses in HaCaT cells while an ethanol extract had a limited effect. The primary glycosaminoglycan (fucosylated chondroitin sulfate; FCS) was purified and tested for anti-inflammatory activity in vivo. FCS modulated the expression of critical genes, including NF-ĸB, TNFα, iNOS, and COX-2, and attenuated inflammation and tissue damage caused by TPA in a mouse ear inflammation model. It also mitigated colonic colitis caused in mice by dextran sodium sulfate. FCS from I. badionotus of the Yucatan Peninsula thus had strong anti-inflammatory properties in vivo.

Toxicity evaluation and microbiota response of the lined sole Achirus lineatus (Chordata: Achiridae) exposed to the light petroleum water-accommodated fraction (WAF).

Exposure to contaminants might directly affect organisms and alter their associated microbiota. The objective of the present study was to determine the impact of the petroleum-water-accommodated fraction (WAF) from a light crude oil (API gravity 35) on a benthic fish species native from the Gulf of Mexico (GoM). Ten adults of Achirus lineatus (Linnaeus, 1758) were exposed to a sublethal WAF/water solution of 50% v/v for 48 hr. Multiple endpoints were measured including tissue damage, presence of polycyclic aromatic hydrocarbons (PAHs) metabolites in bile and gut microbiota analyses. Atrophy and fatty degeneration were observed in livers. Nodules and inflammation were detected in spleen, and structural disintegration and atrophy in the kidney. In gills hyperplasia, aneurysm, and gills lamellar fusion were observed. PAHs metabolites concentrations in bile were significantly higher in exposed organisms. Gut microbiome taxonomic analysis showed significant shifts in bacterial structure and composition following WAF exposure. Data indicate that exposure to WAF produced toxic effects in adults of A. lineatus, as evidenced by histological alterations and dysbiosis, which might represent an impairment to long-term subsistence of exposed aquatic organisms.

Stability of retroviral pseudotypes carrying the hemagglutinin of avian influenza viruses under various storage conditions.

Retroviral pseudotypes are broadly used as safe instruments to mimic the structure and surface of highly pathogenic viruses. They have been employed for the discovery of new drugs, as diagnostic tools in vaccine studies, and part of serological assays. Because of their widespread use in research and their potential as tools for quality control, it is important to know their shelf life, stability, and best storage conditions. In this study, we produced pseudotypes carrying the lacZ reporter gene and the hemagglutinin (HA) of avian influenza virus subtypes H5 and H7 to investigate their stability under various storage conditions. We produced pseudotypes with titers of approximately 106 RLU/mL, which decreased to 105-106 RLU/mL after short-term storage at 4 °C (up to 4 weeks). Stability was maintained after long-term storage at -20 °C (up to 12 months), even under storage variations such as freeze-thaw cycles. We conclude that, although the titers decreased by 1 log10 under the different storage conditions, the remaining titers can be readily applicable in many techniques, such as neutralization assays. These findings show that large quantities of retroviral pseudotypes can be safely stored for short- or long-term use, allowing standardization and reduced variation in assays involving retroviral pseudotypes.

The Plecoptera of Panama. IV. Description of the last nymphal instar for two species of Anacroneuria Klapálek (Plecoptera: Perlidae) from the Caldera River, Chiriquí, Panamá.

The last nymphal instars of Anacroneuria planicollis Klapálek, 1923 and A. quetzali Gutiérrez-Fonseca and Springer, 2015 are described from the Caldera River, Chiriquí Province, Panamá. The adult female of A. quetzali is associated for the first time and described also from the Caldera River, Chiriquí Province, Panamá.

Redescription of the Central American genus Moribaetis Waltz McCafferty 1985 (Ephemeroptera, Baetidae).

A new definition for the genus Moribaetis Waltz McCafferty 1985 is given. Its type species, Moribaetis maculipennis (Flowers 1979) is redescribed based on male and female imagoes reared from larvae near the type locality in Panama. Larvae, formerly wrongly attributed to Moribaetis salvini (Eaton 1885), and a male imago, formerly wrongly attributed to Moribaetis macaferti Waltz 1985, belong to a new species Moribaetis latipennis sp. n., which is described here based on a male imago reared from larva in Panama. Both species, M. maculipennis and M. latipennis sp. n., are distinct from M. salvini, which is known as a single male imago (lectotype) from Costa Rica. All other species, formerly attributed to Moribaetis, are excluded from this genus; a new combination Caribaetis macaferti comb. n. is proposed for the species originally described as Moribaetis macaferti Waltz (in Waltz McCafferty) 1985, and a new combination Baetis (Rhodobaetis) mimbresaurus comb. n. is proposed for the species originally described as Moribaetis mimbresaurus McCafferty 2007.

Anacroneuria (Plecoptera: Perlidae) del río Caldera, Chiriquí, Panamá: nuevos registros de distribución, y comentarios sobre distribución altitudinal y variación estacional / Anacroneuria (Plecoptera: Perlidae) from Caldera River, Chiriquí, Panamá: new distribution records, and comments on altitudinal distribution and seasonal variation

Resumen Plecoptera es un grupo basal de insectos acuáticos, también conocidos como "moscas de piedra". Con el objetivo de contribuir al conocimiento taxonómico y ecológico del género Anacroneuria, se realizaron recolectas de ninfas en la parte alta y media del río Caldera, en la provincia de Chiriquí. Para esto se hicieron giras de campo una vez al mes de enero a diciembre de 2015. En siete estaciones de muestreo, se recolectaron ninfas en rocas y hojarasca sumergida, de forma manual con pinzas entomológicas y con red triangular, para su posterior cría en sistemas de acuarios en el laboratorio. Se recolectaron 485 ninfas, con la emergencia de 138 adultos. Cinco especies de Anacroneuria: Anacroneuria annulipalpis, A. benedettoi, A. planicollis, A. quetzali, A. marca y dos especies no identificadas fueron determinadas a través de la crianza de ninfas en laboratorio. El rango de distribución de A. benedettoi fue extendido a la provincia de Chiriquí. El primer registro de A. quetzalipara Panamá es comentado. Se aporta datos de distribución altitudinal, variabilidad estacional y requerimientos ambientales. Se recomienda ampliar los estudios sobre las asociaciones de ninfas con las formas adultas en otras áreas de Panamá y del Neotrópico, así como incrementar el conocimiento sobre la biología y ecología de este grupo.

Abstract Plecoptera order is a basal group of aquatic insects, also known as stonefly. In order to contribute to the taxonomic and ecological knowledge of the genus Anacroneuria, nymphs were collected in the upper and low parts of the Caldera River, in the Chiriquí province. For this, field trips were carried out once a month, from January to December of 2015. A total of seven stations were sampled, and nymphs were collected on rocks and submerged leaf litter, manually with entomological tweezers, and with a triangular net; nymphs were later transported and reared in aquarium systems in the laboratory, and their growth was followed. A total of 485 nymphs were collected, with the emergence of 138 adults. Five species of Anacroneuria: Anacroneuriaannulipalpis, A. benedettoi, A. planicollis, A. quetzali, A. marca and two unknown species were obtained after nymphs rearing. The distribution range of A. benedettoi was extended to the Chiriqui province. The first record for A. quetzaliin Panamá is commented. In addition, data of altitudinal distribution, seasonal variability and environment requirements were mentioned. We recommend to expand studies on Plecoptera nymph associations with adult forms in other areas of Panama and the Neotropics, as well as to increase the knowledge about their biology and ecology. Rev. Biol. Trop. 66(1): 164-177. Epub 2018 March 01.

Continuous Flow α-Arylation of N,N-Dialkylhydrazones under Visible-Light Photoredox Catalysis.

The first direct α-arylation of aldehyde-derived N,N-dialkylhydrazones with electron deficient aryl and heteroaryl cyanides under visible-light photoredox catalysis has been developed. Structurally complex α,α'-diaryl-N,N-cycloalkylhydrazones were obtained in moderate yields by repetition of the direct arylation protocol. A continuous-flow procedure for the preparation of α-aryl-N,N-dialkylhydrazones on a multigram scale has also been established.

The hemagglutinin of the influenza A(H1N1)pdm09 is mutating towards stability.

The last influenza A pandemic provided an excellent opportunity to study the adaptation of the influenza A(H1N1)pdm09 virus to the human host. Particularly, due to the availability of sequences taken from isolates since the beginning of the pandemic until date, we could monitor amino acid changes that occurred in the hemagglutinin (HA) as the virus spread worldwide and became the dominant H1N1 strain. HA is crucial to viral infection because it binds to sialidated cell-receptors and mediates fusion of cell and viral membranes; because antibodies that bind to HA may block virus entry to the cell, this protein is subjected to high selective pressure. Multiple alignment analysis of sequences of the HA from isolates taken since 2009 to date allowed us to find amino acid changes that were positively selected as the pandemic progressed. We found nine changes that became prevalent: HA1 subunits D104N, K166Q, S188T, S206T, A259T, and K285E; and HA2 subunits E47K, S124N, and E172K. Most of these changes were located in areas involved in inter- and intrachain interactions, while only two (K166Q and S188T) were located in known antigenic sites. We conclude that selective pressure on HA was aimed to improve its functionality and hence virus fitness, rather than at avoidance of immune recognition.

Analysis of adaptation mutants in the hemagglutinin of the influenza A(H1N1)pdm09 virus.

Hemagglutinin is the major surface glycoprotein of influenza viruses. It participates in the initial steps of viral infection through receptor binding and membrane fusion events. The influenza pandemic of 2009 provided a unique scenario to study virus evolution. We performed molecular dynamics simulations with four hemagglutinin variants that appeared throughout the 2009 influenza A (H1N1) pandemic. We found that variant 1 (S143G, S185T) likely arose to avoid immune recognition. Variant 2 (A134T), and variant 3 (D222E, P297S) had an increased binding affinity for the receptor. Finally, variant 4 (E374K) altered hemagglutinin stability in the vicinity of the fusion peptide. Variants 1 and 4 have become increasingly predominant, while variants 2 and 3 declined as the pandemic progressed. Our results show some of the different strategies that the influenza virus uses to adapt to the human host and provide an example of how selective pressure drives antigenic drift in viral proteins.

High serotonin levels due to the presence of the acanthocephalan Hexaglandula corynosoma could promote changes in behavior of the fiddler crab Uca spinicarpa.

Between February and June 2010, 113 fiddler crabs Uca spinicarpa were collected from the Chuburna lagoon system on the northern coast of the Yucatan Peninsula, México. Of the 68 crabs gathered outside their burrows, 13 were infected with 25 cystacanths of Hexaglandula corynosoma (intensity of infection from 1 to 5) and the remaining 55 crabs were uninfected. The other 45 crabs were found inside their burrows and only one was found infected with 1 cystacanth of H. corynosoma. Serotonin (5-HT) levels were higher in the group of crabs infected with H. corynosoma in contrast to the group of uninfected crabs and the group of those infected with other parasites. A redundancy analysis corroborated a positive relationship between 5-HT and the intensity of infection with H. corynosoma. In contrast, dopamine levels remained similar among different groups of crabs.

A mutation in the receptor binding site enhances infectivity of 2009 H1N1 influenza hemagglutinin pseudotypes without changing antigenicity.

The 2009 H1N1 pandemic highlights the need to better understand influenza A infectivity and antigenicity. Relative to other recent seasonal H1N1 influenza strains, the 2009 H1N1 virus grew less efficiently in eggs, which hindered efforts to rapidly supply vaccine. Using lentiviral pseudotypes bearing influenza hemagglutinin (HA-pseudotypes) we evaluated a glutamine to arginine mutation at position 223 (Q223R) and glycosylation at residue 276 in HA for their effects on infectivity and neutralization. Q223R emerged during propagation in eggs and lies in the receptor binding site. We found that the Q223R mutation greatly enhanced infectivity of HA-pseudotypes in human cells, which was further augmented by inclusion of the viral neuraminidase (NA) and M2 proteins. Loss of glycosylation at residue 276 did not alter infectivity. None of these modifications affected neutralization. These findings provide information for increasing 2009 H1N1HA-pseudotype titers without altering antigenicity and offer insights into receptor use.

Homology modeling and molecular dynamics simulations of HgiDII methyltransferase in complex with DNA and S-adenosyl-methionine: catalytic mechanism and interactions with DNA.

M.HgiDII is a methyltransferase (MTase) from Herpetosiphon giganteus that recognizes the sequence GTCGAC. This enzyme belongs to a group of MTases that share a high degree of amino acid similarity, albeit none of them has been thoroughly characterized. To study the catalytic mechanism of M.HgiDII and its interactions with DNA, we performed molecular dynamics simulations with a homology model of M.HgiDII complexed with DNA and S-adenosyl-methionine. Our results indicate that M.HgiDII may not rely only on Glu119 to activate the cytosine ring, which is an early step in the catalysis of cytosine methylation; apparently, Arg160 and Arg162 may also participate in the activation by interacting with cytosine O2. Another residue from the catalytic site, Val118, also played a relevant role in the catalysis of M.HgiDII. Val118 interacted with the target cytosine and kept water molecules from accessing the region of the catalytic pocket where Cys79 interacts with cytosine, thus preventing water-mediated disruption of interactions in the catalytic site. Specific recognition of DNA was mediated mainly by amino acids of the target recognition domain, although some amino acids (loop 80-88) of the catalytic domain may also contribute to DNA recognition. These interactions involved direct contacts between M.HgiDII and DNA, as well as indirect contacts through water bridges. Additionally, analysis of sequence alignments with closely related MTases helped us to identify a motif in the TRD of M.HgiDII that may be relevant to specific DNA recognition.

Presence of Panulirus argus virus 1 (PaV1) in juvenile spiny lobsters Panulirus argus from the Caribbean coast of Mexico.

Macroscopic evidence, histological sections, transmission electron microscopy (TEM) evaluation, and PCR analyses of 25 apparently diseased juvenile spiny lobsters Panulirus argus from the reef lagoon of Puerto Morelos, Mexico, showed the presence of Panulirus argus Virus 1 (PaV1). Cowdry Type A intranuclear viral inclusions were observed in histological analyses, icosahedral viral particles were observed by TEM, and PCR using specific primers for PaV1 amplified a fragment of 499 bp. This is the first report of PaV1 infecting P. argus outside the Florida Keys, USA.

Fluorous-tagged carbamates for the pd-catalyzed amination of aryl halides.

A novel fluorous-tagged ammonia surrogate has been synthesized and its application to the synthesis of anilines by Buchwald-Hartwig palladium-catalyzed amidation-hydrolysis protocol is described. Primary anilines were obtained in moderate to good yields after a sequence of two reaction steps involving fluorous separation techniques for their purification. Preliminary results indicate that N-substituted anilines can also be obtained using just N-substituted-FBoc carbamates as the nitrogen source.