Dominance of Three Sublineages of the SARS-CoV-2 Delta Variant in Mexico.

In this study, we analyzed the sequences of SARS-CoV-2 isolates of the Delta variant in Mexico, which has completely replaced other previously circulating variants in the country due to its transmission advantage. Among all the Delta sublineages that were detected, 81.5 % were classified as AY.20, AY.26, and AY.100. According to publicly available data, these only reached a world prevalence of less than 1%, suggesting a possible Mexican origin. The signature mutations of these sublineages are described herein, and phylogenetic analyses and haplotype networks are used to track their spread across the country. Other frequently detected sublineages include AY.3, AY.62, AY.103, and AY.113. Over time, the main sublineages showed different geographical distributions, with AY.20 predominant in Central Mexico, AY.26 in the North, and AY.100 in the Northwest and South/Southeast. This work describes the circulation, from May to November 2021, of the primary sublineages of the Delta variant associated with the third wave of the COVID-19 pandemic in Mexico and highlights the importance of SARS-CoV-2 genomic surveillance for the timely identification of emerging variants that may impact public health.

3D-bioengineered model of human skeletal muscle tissue with phenotypic features of aging for drug testing purposes.

Three-dimensional engineering of skeletal muscle is becoming increasingly relevant for tissue engineering, disease modeling and bio-hybrid robotics, where flexible, versatile and multidisciplinary approaches for the evaluation of tissue differentiation, functionality and force measurement are required. This works presents a 3D-printed platform of bioengineered human skeletal muscle which can efficiently model the three-dimensional structure of native tissue, while providing information about force generation and contraction profiles. Proper differentiation and maturation of myocytes is demonstrated by the expression of key myo-proteins using immunocytochemistry and analyzed by confocal microscopy, and the functionality assessed via electrical stimulation and analysis of contraction kinetics. To validate the flexibility of this platform for complex tissue modeling, the bioengineered muscle is treated with tumor necrosis factorαto mimic the conditions of aging, which is supported by morphological and functional changes. Moreover, as a proof of concept, the effects of Argireline® Amplified peptide, a cosmetic ingredient that causes muscle relaxation, are evaluated in both healthy and aged tissue models. Therefore, the results demonstrate that this 3D-bioengineered human muscle platform could be used to assess morphological and functional changes in the aging process of muscular tissue with potential applications in biomedicine, cosmetics and bio-hybrid robotics.

Synthesis, antimycobacterial and cytotoxic activity of α,ß-unsaturated amides and 2,4-disubstituted oxazoline derivatives.

The synthesis of six α,ß,-unsaturated amides and six 2,4-disubstituted oxazolines derivatives and their evaluation against two Mycobacterium tuberculosis strains (sensitive H37Rv and a resistant clinical isolate) is reported. 2,4-Disubstituted oxazolines (S)-3b,d,e were the most active in the sensitive strain with a MIC of 14.2, 13.6 and 10.8µM, respectively, and the compounds (S)-3d,f were the most active against resistant strain with a MIC of 6.8 and 7.4µM. The ex-vivo evaluation of hepatotoxicity on precision-cut rat liver slices was also tested for the α,ß-unsaturated amides (S)-2b and (S)-2d,f and for the oxazolines (S)-3b and (S)-3d,f at different concentrations (5, 15 and 30µg/mL). The results indicate that these compounds possess promising antimycobacterial activity and at the same time are not hepatotoxic. These findings open the possibility for development of new drugs against tuberculosis.

Inhibition of the mitotic exit network in response to damaged telomeres.

When chromosomal DNA is damaged, progression through the cell cycle is halted to provide the cells with time to repair the genetic material before it is distributed between the mother and daughter cells. In Saccharomyces cerevisiae, this cell cycle arrest occurs at the G2/M transition. However, it is also necessary to restrain exit from mitosis by maintaining Bfa1-Bub2, the inhibitor of the Mitotic Exit Network (MEN), in an active state. While the role of Bfa1 and Bub2 in the inhibition of mitotic exit when the spindle is not properly aligned and the spindle position checkpoint is activated has been extensively studied, the mechanism by which these proteins prevent MEN function after DNA damage is still unclear. Here, we propose that the inhibition of the MEN is specifically required when telomeres are damaged but it is not necessary to face all types of chromosomal DNA damage, which is in agreement with previous data in mammals suggesting the existence of a putative telomere-specific DNA damage response that inhibits mitotic exit. Furthermore, we demonstrate that the mechanism of MEN inhibition when telomeres are damaged relies on the Rad53-dependent inhibition of Bfa1 phosphorylation by the Polo-like kinase Cdc5, establishing a new key role of this kinase in regulating cell cycle progression.

Induction of virulence factors, apoptosis, and cytokines in precision-cut hamster liver slices infected with Entamoeba histolytica.

Precision-cut liver slices (PCLS) are mainly used to evaluate hepatotoxicity and metabolism of chemicals, as well as to study mechanisms of liver damage and repair. However, recently they have been used as a system to study amoebic infections. The aim of this study was to validate this model as an alternative for experimental amoebic liver absess (ALA) in animals. To do this, the PCLS was analyzed for the expression of amoebapore and cysteine proteinases 1 and 5, three of the most studied virulence factors of Entamoeba histolytica, as well as the induction of apoptosis and cytokines production in response to the ex vivo infection. PCHLS were prepared with the Brendel-Vitron tissue slicer and then, infected with 200,000 trophozoites of E. histolytica. Samples were taken at 0, 6, 12, 18, and 24 h and compared to control non-infected slices. Morphological studies were performed in order to verify the infection; while apoptosis was studied by TUNEL and PAS techniques. The expression of cysteine proteinases (1 and 5), and amoebapore, was analyzed by real-time PCR. By using ELISA assays, the production of cytokines was also studied. PCHLS were found to be a reproducible infection system, and E. histolytica caused the expression of cysteine proteinases and amoebapore in infected slices. At the same time, trophozoites induce release of cytokines and apoptotic death of the hepatocytes close to them. PCHLS represent a new and suitable alternative model to study the pathogenesis of hepatic amoebiasis.

First record of Neobenedenia melleni (Monogenea: Capsalidae) in sea-farmed cobia (Rachycentron canadum) in Brazil.

Neobenedenia melleni (MacCallum, 1927) (Monogenea) is a widespread pathogen in marine teleost cultures all over the world. The present paper reports this parasite species in farmed cobia (Rachycentron canadum) in Brazil, for the first time. Some comments on preventive actions for avoiding the disease are made.

First record of Neobenedenia melleni (Monogenea: Capsalidae) in sea-farmed cobia (Rachycentron canadum) in Brazil / Primeiro registro de Neobenedenia melleni (Monogenea: Capsalidae) em cultivo de bijupirás (Rachycentron canadum) no Brasil

Neobenedenia melleni (MacCallum, 1927) (Monogenea) is a widespread pathogen in marine teleost cultures all over the world. The present paper reports this parasite species in farmed cobia (Rachycentron canadum) in Brazil, for the first time. Some comments on preventive actions for avoiding the disease are made.

Neobenedenia melleni (MacCallum, 1927) (Monogenea) é um patógeno amplamente distribuído em cultivo de teleósteos marinhos no mundo. Este estudo relata pela primeira vez essa espécie de parasito em cultivo de cobia, Rachycentron canadum, no Brasil. Comentários sobre prevenção para evitar a doença são discutidos.

Tem1 localization to the spindle pole bodies is essential for mitotic exit and impairs spindle checkpoint function.

The mitotic exit network (MEN) is a signaling cascade that triggers inactivation of the mitotic cyclin-dependent kinases and exit from mitosis. The GTPase Tem1 localizes on the spindle pole bodies (SPBs) and initiates MEN signaling. Tem1 activity is inhibited until anaphase by Bfa1-Bub2. These proteins are also part of the spindle position checkpoint (SPOC), a surveillance mechanism that restrains mitotic exit until the spindle is correctly positioned. Here, we show that regulation of Tem1 localization is essential for the proper function of the MEN and the SPOC. We demonstrate that the dynamics of Tem1 loading onto SPBs determine the recruitment of other MEN components to this structure, and reevaluate the interdependence in the localization of Tem1, Bfa1, and Bub2. We also find that removal of Tem1 from the SPBs is critical for the SPOC to impede cell cycle progression. Finally, we demonstrate for the first time that localization of Tem1 to the SPBs is a requirement for mitotic exit.

Precision-cut hamster liver slices as an ex vivo model to study amoebic liver abscess.

Entamoeba histolytica is the etiological agent of amoebiasis, the second cause of global morbidity and mortality due to parasitic diseases in humans. In approximately 1% of the cases, amoebas penetrate the intestinal mucosa and spread to other organs, producing extra-intestinal lesions, among which amoebic liver abscess (ALA) is the most common. To study ALA, in vivo and in vitro models are used. However, animal models may pose ethical issues, and are time-consuming and costly; and cell cultures represent isolated cellular lineages. The present study reports the infection of precision-cut hamster liver slices with Entamoeba histolytica trophozoites. The infection time-course, including tissue damage, parallels findings previously reported in the animal model. At the same time amoebic virulence factors were detected in the infected slices. This new model to study ALA is simple and reproducible, and employs less than 1/3 of the hamsters required for in vivo analyses.