Biology subjects

Gonzalez, A. M.

Publications and source records attributed to Gonzalez, A. M..

8 recordsLinked to original sources

bioRxiv2026

Functional export of NDM-7 to outer membrane vesicles in Klebsiella pneumoniae compromises imipenem and cefiderocol activity

The carbapenemases KPC and NDM are the most widespread determinants of carbapenem resistance in Klebsiella pneumoniae. Whereas KPC is a soluble periplasmic serine-{beta}-lactamase, NDM is a membrane-anchored metallo-{beta}-lactamase (MBL), a feature that promotes its incorporation into outer membrane vesicles (OMVs). OMVs are naturally released nanoparticles that deliver diverse bioactive cargo, including enzymes, virulence factors, and signaling molecules, and may contribute to antibiotic resistance. Here, we investigated the export and activity of carbapenemases in OMVs produced by carbapenem-resistant Klebsiella pneumoniae clinical isolates expressing NDM-7, an emerging variant, or KPC-2, as well as in isogenic laboratory-derived K. pneumoniae strains producing NDM-1, NDM-7 or KPC-2. NDM enzymes were detected in vesicles released by NDM-producing strains, whereas KPC-2 remained confined to the cellular fraction and was not observed in OMVs. OMVs contained catalytically active NDM enzyme and conferred protection to susceptible K. pneumoniae against imipenem. Importantly, NDM-positive OMVs also partially restored bacterial growth in the presence of cefiderocol, a siderophore cephalosporin used to treat infections caused by MBL producers. This protective effect was more pronounced for NDM-7 than for NDM-1. Together, these findings show that the clinically emerging NDM-7 variant is efficiently packaged into OMVs in K. pneumoniae and remains enzymatically active, allowing extracellular antibiotic degradation and conferring protection to susceptible bacteria exposed to carbapenems and cefiderocol.

microbiology↗

bioRxiv2025

New distribution records of Aedes aegypti, Aedes mediovittatus, and Toxorhynchites portoricensis (Diptera: Culicidae) in Puerto Rico and their relevance to Integrated Vector Management

As of October 2025, Puerto Rico has been experiencing an ongoing dengue outbreak that started in March 2024. The latest island-wide mosquito survey conducted in Puerto Rico during 2018- 2019 covered 41 of the 78 municipalities and detected the presence of Aedes aegypti in 27 of the municipalities. Given the prolonged elevated circulation of dengue virus on the island, we carried out an additional Ae. aegypti survey in June 2025 across 44 out of 78 municipalities, including areas with no prior records of the species. Here, we report the occurrence of Ae. aegypti in 43 out of 44 municipalities surveyed, including ten new municipalities where Ae. aegypti has not been reported. These findings provide insight into the dispersal of Ae. aegypti in Puerto Rico, indicating that the species is much more widespread than previously known. We also provide the expanded species occurrence of Aedes mediovittatus and Toxorhynchites portoricensis, which share the same larval habitat as Ae. aegypti. Notably, 96% of cemeteries surveyed across 24 municipalities served as oviposition sites for Ae. aegypti. However, a few cemeteries demonstrated effective preventative practices that minimize mosquito breeding. This effective management, which resulted in no mosquito breeding in some cemeteries and a tire shop, brings hope that communication and education of property/facility managers can reduce the mosquito populations.

ecology↗

bioRxiv2024

Exogenous lipid vesicles induce endocytosis-mediated cellular aggregation in a close unicellular relative of animals

Capsaspora owczarzaki is a protozoan that may both reveal aspects of animal evolution and also curtail the spread of schistosomiasis, a neglected tropical disease. Capsaspora exhibits a chemically regulated aggregative behavior that resembles cellular aggregation in some animals. This behavior may have played a key role in the evolution of animal multicellularity. Additionally, this aggregative behavior may be important for Capsasporas ability to colonize the intermediate host of parasitic schistosomes and potentially prevent the spread of schistosomiasis. Both applications demand elucidation of the molecular mechanism of Capsaspora aggregation. Toward this goal, we first determined the necessary chemical properties of lipid cues that activate aggregation. We found that a wide range of abundant zwitterionic lipids induced aggregation, revealing that the aggregative behavior could be activated by diverse lipid-rich conditions. Furthermore, we demonstrated that aggregation in Capsaspora requires clathrin-mediated endocytosis, highlighting the potential significance of endocytosis-linked cellular signaling in recent animal ancestors. Finally, we found that aggregation was initiated by post-translational activation of cell-cell adhesion--not transcriptional regulation of cellular adhesion machinery. Our findings illuminate the chemical, molecular and cellular mechanisms that regulate Capsaspora aggregative behavior--with implications for the evolution of animal multicellularity and the transmission of parasites.

biochemistry↗

bioRxiv2023

The concreteness effect from memory illusions' perspective: the DIM-HA effect

A vast body of evidence has shown that concrete nouns are processed faster and more accurately than abstract nouns in a variety of cognitive tasks. This phenomenon is widely known as the concreteness effect and explanations for its occurrence seem to reflect differences in processing and organization between both type of concepts. While there is considerable evidence to support this concrete effect, the nature of these differences is still controversial. In developing this explanation, we have proposed a relatively different approach from a false memory perspective using the DRM paradigm. Three different experiments were created to address the importance of association in creating concrete and abstract false memories. Results showed that false recognition rates differed significantly between concrete and abstract critical words when they were associated strongly with their respective lists, which led to a higher proportion of abstract false alarms both in behavioral and electrophysiological experiments. The principal outcomes were discussed in terms of theories of associative activation and qualitatively different representation.

neuroscience↗

bioRxiv2022

Habitat protection and restoration: win-win opportunities for migratory birds in the Northern Andes

Identifying strategies that offer co-benefits for biodiversity protection, forest restoration and human well-being are important for successful conservation outcomes. In this study, we identified opportunities where forest restoration and rehabilitation programs in Colombia also align with priority areas for the conservation of Neotropical migratory birds. We used citizen science eBird-based abundance estimates to define regions with the highest richness of Neotropical migratory birds of conservation concern at montane elevations in Colombia and aligned these high richness areas with domestic initiatives for forest protection (Forest Areas), restoration (Restoration Areas) and rehabilitation (Rehabilitation Areas). We quantified the location and amounts of these three areas as well as the type of land protection and designation within them, specifically, National Protected Areas, Indigenous Reserves, Afro-descendent territories, and regions affected by poverty and violence that are prioritized for rural development by the Colombian government in Post-conflict Territorially Focused Development Programs (PDET). Almost half of Forest Areas overlapped with PDETs where goals for economic development present a risk of forest loss if not done sustainably. There was a 20% overlap between Forest Areas and Afro-descendant territories and indigenous reserves; most of this overlap was outside of established protected areas thus presenting an opportunity for community forest conservation that benefits migratory birds. We found an alignment of less than 6% between migrant bird focal areas and the priority Restoration and Rehabilitation Planning Areas identified by the Colombian National Restoration Plan indicating less opportunity for these programs to simultaneously benefit Neotropical migrant species. Our approach highlights that timely and efficient conservation of declining migrants depends on identifying the regions and strategies that incorporate local communities as part of the solution to forest loss and degradation in Colombia. HighlightsColombia covers over half of key wintering areas for migratory birds in South America Most of the migrants overwinter range overlaps with working landscapes Priority national restoration/rehabilitation areas are ineffective to benefit migrants Forest conservation needs actions involving vulnerable and minority groups

ecology↗

bioRxiv2021

Condensin-driven loop extrusion on supercoiled DNA

Condensin, a structural maintenance of chromosomes (SMC) complex, has been shown to be a molecular motor protein that organizes chromosomes by extruding loops of DNA. In cells, such loop extrusion is challenged by many potential conflicts, e.g., the torsional stresses that are generated by other DNA-processing enzymes. It has so far remained unclear how DNA supercoiling affects loop extrusion. Here, we use time-lapse single-molecule imaging to study condensin-driven DNA loop extrusion on supercoiled DNA. We find that condensin binding and DNA looping is stimulated by positive supercoiled DNA where it preferentially binds near the tips of supercoiled plectonemes. Upon loop extrusion, condensin collects all nearby plectonemes into a single supercoiled loop that is highly stable. Atomic force microscopy imaging shows that condensin generates supercoils in the presence of ATP. Our findings provide insight into the topology-regulated loading and formation of supercoiled loops by SMC complexes and clarify the interplay of loop extrusion and supercoiling.

biophysics↗

bioRxiv2020

Exacerbation of mitochondrial fission in human CD34+ cells halts erythropoiesis and hemoglobin biosynthesis

Erythropoiesis is the most powerful cellular differentiation and proliferation system, with a production of 1011 cells per day. In this fine-tuned process, the hematopoietic stem cells (HSCs) generate erythroid progenitors, which proliferate and mature into erythrocytes. During erythropoiesis, mitochondria are reprogrammed to drive the differentiation process before finally being eliminated by mitophagy. In erythropoiesis, mitochondrial dynamics (MtDy) is expected to be a regulatory key point that has not been described previously. We described that a specific MtDy pattern is occurring in human erythropoiesis from EPO-induced human CD34+ cells, characterized by a predominant mitochondrial fusion at early stages followed by predominant fission at late stages. The fusion protein MFN1 and the fission protein FIS1 are shown to play a key role in the accurate progression of erythropoiesis. Fragmentation of the mitochondrial web by the overexpression of FIS1 (gain of fission) resulted in both the inhibition of hemoglobin biosynthesis and the arrest of erythroid differentiation, keeping cells in immature differentiation stages. These cells showed specific mitochondrial features as compared with control cells, such as an increase in round and large mitochondria morphology, low mitochondrial membrane potential and a drop in the expression of the respiratory complexes II and IV. Interestingly, treatment with the mitochondrial permeability transition pore (mPTP) inhibitor cyclosporin A, rescued mitochondrial morphology, hemoglobin biosynthesis and erythropoiesis. Studies presented in this work revealed MtDy as a hot spot in the regulation of erythroid differentiation which might be signaling downstream for metabolic reprogramming through the aperture/close of the mPTP. Key Points-. Excessive fission disrupts erythroid progression, heme biosynthesis and mitochondrial function, keeping cells mostly in progenitors and proerythroblast stage. -. Mitochondrial Dynamics signaling for erythroid differentiation involves FIS1 and the mPTP

cell biology↗

bioRxiv2018

RESISTANCE TRAINING DOES NOT INDUCE UNIFORM ADAPTATIONS TO QUADRICEPS MUSCLES

Resistance training may differentially affect morphological adaptations along the length of uni-articular and bi-articular muscles. The purpose of this study was to compare changes in muscle morphology along the length of the rectus femoris (RF) and vastus lateralis (VL) in response to resistance training. Following a 2-wk preparatory phase, 15 resistance-trained men (24.0 {+/-} 3.0 y, 90.0 {+/-} 13.8 kg, 174.9 {+/-} 20.7 cm) completed pre-training (PRE) assessments of muscle thickness (MT), pennation angle (PA), cross-sectional area (CSA), and echo-intensity in the RF and VL at 30, 50, and 70% of each muscles length; fascicle length (FL) was estimated from respective measurements of MT and PA within each muscle and region. Participants then began a high intensity, low volume (4 x 3 - 5 repetitions, 3min rest) lower-body resistance training program, and repeated all PRE-assessments after 8 weeks (2 d {middle dot} wk-1) of training (POST). Although three-way (muscle [RF, VL] x region [30, 50, 70%] x time [PRE, POST]) repeated measures analysis of variance did not reveal significant interactions for any assessment of morphology, significant simple (muscle x time) effects were observed for CSA (p = 0.002) and FL (p = 0.016). Specifically, average CSA changes favored the VL (2.96 {+/-} 0.69 cm2, pp < 0.001) over the RF (0.59 {+/-} 0.20 cm2, p = 0.011), while significant decreases in average FL were noted for the RF (-1.03 {+/-} 0.30 cm, p = 0.004) but not the VL (-0.05 {+/-} 0.36 cm, p = 0.901). No other significant differences were observed. The findings of this study demonstrate the occurrence of non-homogenous adaptations in RF and VL muscle size and architecture following 8 weeks of high-intensity resistance training in resistance-trained men. However, training does not appear to influence region-specific adaptations in either muscle.

physiology↗