Biology subjects

Reyes, R.

Publications and source records attributed to Reyes, R..

12 recordsLinked to original sources

bioRxiv2026

A dispersal model for Cenchrus setaceus (Poaceae) in Mexican urban context

Urban environments suffer from multiple ecological issues, such as the invasion of alien. In Mexico, Cenchrus setaceus (African fountain grass) has been introduced as an ornamental species in the 1990s spreading all around the country. The aim of the present study is to propose an invasion models, based on the temporal dispersion of C. setaceus seeds using field data from the metropolitan area of Guadalajara, Jalisco, distinguished between planted individuals from self-propagated ones, quantifying seeds fertility ex situ. Model indicate that the current infested area of the Guadalajara metropolitan area could reach 51-89% within 100 years. Applied to three cities in Chiapas, the model shows limited spread over 50-year period from existing foci but strong sensitivity to new ornamental introductions. An analysis of containment strategies estimates an invasion front velocity of 0.13 km/year and identifies a 3-km-wide buffer zone as necessary to halt spread over a 25-year horizon.

ecology↗

bioRxiv2026

Spatiotemporal distribution of Delta-like protein 1 during mouse pituitary ontogeny and its relationship with differentiating endocrine cell populations

Delta-like protein 1 (DLK1) is a transmembrane protein involved in the regulation of cellular differentiation and stem cell maintenance in several tissues, including the pituitary gland. Although DLK1 expression has been reported in the adult pituitary, its spatiotemporal distribution during mouse pituitary development remains incompletely characterized. The aim of this study was to analyse the distribution of DLK1 during embryonic and postnatal development of the mouse pituitary gland and to characterize its relationship with hormone-producing cell populations. Immunohistochemistry was performed in Swiss albino mice from embryonic day 9.5 (e9.5) to postnatal day 15 (p15). Double immunofluorescence was used at e18.5 and p15 to examine the association of DLK1 immunoreactivity with ACTH-, TSH-, GH-, FSH- and PRL-producing cells. DLK1 immunoreactivity was detected from the earliest stages of pituitary development in Rathke's pouch and the ventral diencephalon. During embryonic development, DLK1-ir cells were widely distributed throughout adenohypophyseal and neurohypophyseal primordia. As development progressed, DLK1 immunoreactivity became progressively regionalized within the anterior, intermediate and tuberal lobes, as well as in the median eminence of the hypothalamus and the posterior pituitary lobe. Cells displaying overlapping immunoreactivity for DLK1 and all hormone-producing cell populations analysed were observed at e18.5 and p15. Semiquantitative analysis at p15 indicated that approximately 32% of adenohypophyseal cells were DLK1-immunoreactive. These findings provide a detailed description of the spatiotemporal distribution of DLK1 during mouse pituitary ontogeny and suggest that DLK1 immunoreactivity is associated with differentiating endocrine cell populations throughout pituitary development.

Developmental Biology↗

bioRxiv2026

A mathematical model for the efficient control of the New World screwworm

An outbreak of New World screwworm has recently been spreading across Mexico, after more than 30 years of absence. The sterile insect technique, which consists of the massive release of sterilized males, has proven to be one of the most efficient methods for controlling the screwworm pest. However, given the limited number of sterile males available, improving the release strategy is critical. We propose a mathematical model of population dynamics adapted to the biology of Cochliomyia hominivorax and derive a feedback control function to determine the number of sterile males to release. We further construct a Luenberger observer to estimate wild fly populations from infected animal counts--the variable monitored by Mexican sanitary authorities--enabling field implementation of the control function. We show that eradication is achievable within approximately 60-100 weeks and that eradication time is governed primarily by the intrinsic biology of the system rather than by infestation magnitude. We then extend the model to a spatially explicit framework and show that when sterile male releases are applied at the outbreak focus and within a 120 km radius, eradication of the pest is attainable.

ecology↗

bioRxiv2026

Colocalization of dopamine D1 and D2 receptors with neuronal nitric oxide synthase in the rat paraventricular nucleus: a structural basis for dopaminergic/nitrergic interaction

The paraventricular nucleus (PVN) plays a central role in neuroendocrine and autonomic regulation, including male sexual behavior. Dopaminergic and nitrergic signaling within the PVN are functionally linked, but their cellular relationship remains unclear. We examined the colocalization of dopamine D1 and D2 receptors with neuronal nitric oxide synthase (nNOS) in adult male rats using double-label immunohistochemistry. nNOS-immunoreactive neurons were widely distributed in PVN, with subsets co-expressing D1R or D2R. Approximately 45% of nNOS-positive neurons expressed dopaminergic receptors. These findings provide structural evidence for dopaminergic-nitrergic interaction in the PVN and support the possibility of direct dopaminergic modulation of nitrergic neurons.

neuroscience↗

bioRxiv2023

Cross-species transmission and PB2 mammalian adaptations of highly pathogenic avian influenza A/H5N1 viruses in Chile

H5N1 highly pathogenic avian influenza viruses (HPAIV) emerged in wild birds in Chile in December 2022 and spilled over into poultry, marine mammals, and one human. Between December 9, 2022 - March 14, 2023, a coordinated government/academic response detected HPAIV by real-time RT-PCR in 8.5% (412/4735) of samples from 23 avian and 3 mammal orders. Whole-genome sequences obtained from 77 birds and 8 marine mammals revealed that all Chilean H5N1 viruses belong to lineage 2.3.4.4b and cluster monophyletically with viruses from Peru, indicating a single introduction from North America into Peru/Chile. Mammalian adaptations were identified in the PB2 segment: D701N in two sea lions, one human, and one shorebird, and Q591K in the human and one sea lion. Minor variant analysis revealed that D701N was present in 52.9 - 70.9% of sequence reads, indicating the presence of both genotypes within hosts. Further surveillance of spillover events is warranted to assess the emergence and potential onward transmission of mammalian adapted H5N1 HPAIV in South America.

microbiology↗

bioRxiv2022

Dynamic readout of the Hh gradient in the Drosophila wing disc reveals pattern-specific tradeoffs between robustness and precision

How patterning by morphogen gradients determine tradeoffs between robustness and precision is unclear. Gradients that exhibit self-enhanced ligand degradation provide robustness to perturbations in morphogen production rates. However, increased robustness achieved through this mechanism is traded off for lower precision to noise. Here we use a hypotheses-driven theoretical approach to show that Hedge-hog (Hh) signaling would confer the same robustness to all target genes established by the steady-state gradient, but when a dynamical interpretation of patterning is used, robustness is maintained for steady-state outputs, but is traded off for higher precision in outputs set prior to steady-state. As predicted by our model, the widths of decapentaplegic (dpp), and collier (col), two target genes established by the Hh gradient in the Drosophila wing disc, exhibit differential robustness to Hh dosage. Particularly, higher robustness in the col pattern is ensured by Hh-dependent upregulation of its receptor Patched, an evolutionary-conserved property of Hh signaling that results in self-promoted Hh degradation. In contrast, dpp expression that is determined by the transient overshoot gradient, is insensitive to self-enhanced ligand degradation and exhibits less robustness, in exchange for a more precise boundary. Our work reveals of how morphogen gradients can establish tunable patterning properties in a target-specific manner.

developmental biology↗

bioRxiv2022

Like mother, like daughter? Phenotypic plasticity, environmental covariation, and heritability of size in a parthenogenetic wasp

Dinocampus coccinellae (Hymenoptera:Braconidae, Euphorinae) is a solitary, generalist Braconid parasitoid wasp that reproduces through thelytokous parthenogenesis, an asexual process in which diploid daughters emerge from unfertilized eggs, and parasitizes over fifty diverse species of coccinellid ladybeetles worldwide as hosts. Here we utilized a common garden and reciprocal transplant experiment using parthenogenetic lines of D. coccinellae presented with three different host ladybeetle species of varying sizes, across multiple generations to investigate heritability, plasticity, and environmental covariation of body size in D. coccinellae. We expected positively correlated parent-offspring parasitoid regressions, indicative of heritable size variation, from unilineal (parent and offspring reared on same host species) lines, since these restrict environmental variation in phenotypes. In contrast, because multilineal (parent and offspring reared on different host species) lines would induce phenotypic plasticity of clones reared in varying environments, we expected negatively correlated parent-offspring parasitoid regressions. Our results indicate (1) little heritable variation in body size, (2) strong independence of offspring size on the host environment, (3) a consistent signal of size-host tradeoff wherein small mothers produced larger offspring, and vice versa, independent of host environment. We then model the evolution of size and host-shifting under a constrained fecundity advantage model of Copes Law using a Hidden Markov Model, showing that D. coccinellae likely has considerable fitness advantage to maintain phenotypic plasticity in body size despite parthenogenetic reproduction.

evolutionary biology↗

bioRxiv2022

Disruption of lysosomal proteolysis in astrocytes facilitates midbrain proteostasis failure in an early-onset PD model.

Accumulation of advanced glycation end products (AGEs) on biopolymers accompany cellular aging and drives poorly understood disease processes. Here, we studied how AGEs contribute to development of early on-set Parkinsons Disease (PD) caused by loss-of-function of DJ1, a protein deglycase. In induced pluripotent stem cell (iPSC)-derived midbrain organoid models deficient for DJ1 activity, we find that lysosomal proteolysis is impaired, causing AGEs to accumulate, -synuclein (-syn) phosphorylation to increase, and proteins to aggregate. These processes are at least partly driven by astrocytes, as DJ1 loss reduces their capacity to provide metabolic support and triggers acquisition of a pro-inflammatory phenotype. Consistently, in co-cultures, we find that DJ1-expressing astrocytes are able to reverse the proteolysis deficits of DJ1 knockout midbrain neurons. In conclusion, astrocytes capacity to clear toxic damaged proteins is critical to preserve neuronal function and their dysfunction contributes to the neurodegeneration observed in PD.

neuroscience↗

bioRxiv2021

SARS-CoV-2 spike-specific memory B cells express markers of durable immunity after non-severe COVID-19 but not after severe disease

SARS-CoV-2 infection elicits a robust B cell response, resulting in the generation of long-lived plasma cells and memory B cells. Here, we aimed to determine the effect of COVID-19 severity on the memory B cell response and characterize changes in the memory B cell compartment between recovery and five months post-symptom onset. Using high-parameter spectral flow cytometry, we analyzed the phenotype of memory B cells with reactivity against the SARS-CoV-2 spike protein or the spike receptor binding domain (RBD) in recovered individuals who had been hospitalized with non-severe (n=8) or severe (n=5) COVID-19. One month after symptom onset, a substantial proportion of spike-specific IgG+ B cells showed an activated phenotype. In individuals who experienced non-severe disease, spike-specific IgG+ B cells showed increased expression of markers associated with durable B cell memory, including T-bet, FcRL5, and CD11c, which was not observed after severe disease. Five months post-symptom onset, the majority of spike-specific memory B cells had a resting phenotype and the percentage of spike-specific T-bet+ IgG+ memory B cells decreased to baseline levels. Collectively, our results suggest that the memory B cell response elicited during non-severe COVID-19 may be of higher quality than the response after severe disease.

immunology↗

bioRxiv2021

The Effects of Incline Level on Optimized Lower-Limb Exoskeleton Assistance

For exoskeletons to be successful in real-world settings, they will need to be effective across a variety of terrains, including on inclines. While some single-joint exoskeletons have assisted incline walking, recent successes in level-ground assistance suggest that greater improvements may be possible by optimizing assistance of the whole leg. To understand how exoskeleton assistance should change with incline, we used human-in-the-loop optimization to find whole-leg exoskeleton assistance torques that minimized metabolic cost on a range of grades. We optimized assistance for three expert, able-bodied participants on 5 degree, 10 degree and 15 degree inclines using a hip-knee-ankle exoskeleton emulator. For all assisted conditions, the cost of transport was reduced by at least 50% relative to walking in the device with no assistance, a large improvement to walking that is comparable to the benefits of whole-leg assistance on level-ground. This corresponds to large absolute reductions in metabolic cost, with the most strenuous conditions reduced by 4.9 W/kg, more than twice the entire energy cost of level walking. Optimized extension torque magnitudes and exoskeleton power increased with incline, with hip extension, knee extension and ankle plantarflexion often growing as large as allowed by comfort-based limits. Applied powers on steep inclines were double the powers applied during level-ground walking, indicating that larger exoskeleton power may be optimal in scenarios where biological powers and costs are higher. Future exoskeleton devices can be expected to deliver large improvements in walking performance across a range of inclines, if they have sufficient torque and power capabilities.

bioengineering↗

bioRxiv2021

Optimized hip-knee-ankle exoskeleton assistance at a range of walking speeds

BackgroundEffective autonomous exoskeletons will need to be useful at a variety of walking speeds, but we do not know how optimal exoskeleton assistance should change with speed. Optimal exoskeleton assistance may increase with speed similar to biological torque changes or a well-tuned assistance profile may be effective at a variety of speeds. MethodsWe optimized hip-knee-ankle exoskeleton assistance to reduce metabolic cost for three participants walking at 1.0 m/s, 1.25 m/s and 1.5 m/s. We measured metabolic cost, muscle activity, exoskeleton assistance and kinematics. We performed two tailed paired t-tests to determine significance. ResultsExoskeleton assistance reduced the metabolic cost of walking compared to wearing the exoskeleton with no torque applied by 26%, 47% and 50% at 1.0, 1.25 and 1.5 m/s, respectively. For all three participants, optimized exoskeleton ankle torque was the smallest for slow walking, while hip and knee torque changed slightly with speed in ways that varied across participants. Total applied positive power increased with speed for all three participants, largely due to increased joint velocities, which consistently increased with speed. ConclusionsExoskeleton assistance is effective at a range of speeds and is most effective at medium and fast walking speeds. Exoskeleton assistance was less effective for slow walking, which may explain the limited success in reducing metabolic cost for patient populations through exoskeleton assistance. Exoskeleton designers may have more success when targeting activities and groups with faster walking speeds. Speed-related changes in optimized exoskeleton assistance varied by participant, indicating either the benefit of participant-specific tuning or that a wide variety of torque profiles are similarly effective.

bioengineering↗

bioRxiv2021

Comparing optimized exoskeleton assistance of the hip, knee, and ankle in single and multi-joint configurations

Exoskeletons that assist the hip, knee, and ankle joints have begun to improve human mobility, particularly by reducing the metabolic cost of walking. However, direct comparisons of optimal assistance of these joints, or their combinations, have not yet been possible. Assisting multiple joints may be more beneficial than the sum of individual effects, because muscles often span multiple joints, or less effective, because single-joint assistance can indirectly aid other joints. In this study, we used a hip-knee-ankle exoskeleton emulator paired with human-in-the-loop optimization to find single-joint, two-joint, and whole-leg assistance that maximally reduced the metabolic cost of walking for three participants. Hip-only and ankle-only assistance reduced the metabolic cost of walking by 26% and 30% relative to walking in the device unassisted, confirming that both joints are good targets for assistance. Knee-only assistance reduced the metabolic cost of walking by 13%, demonstrating that effective knee assistance is possible. Two-joint assistance reduced the metabolic cost of walking by between 34% and 42%, with the largest improvements coming from hip-ankle assistance. Assisting all three joints reduced the metabolic cost of walking by 50%, showing that at least half of the metabolic energy expended during walking can be saved through exoskeleton assistance. Changes in kinematics and muscle activity indicate that single-joint assistance indirectly assisted muscles at other joints, such that the improvement from whole-leg assistance was smaller than the sum of its single-joint parts. Exoskeletons can assist the entire limb for maximum effect, but a single well-chosen joint can be more efficient when considering additional factors such as weight and cost.

bioengineering↗