Biology subjects

Alvarado, S. G.

Publications and source records attributed to Alvarado, S. G..

7 recordsLinked to original sources

bioRxiv2026

Hippocampal extracellular matrix remodeling and temporally distinct glial reorganization following peripheral injury

Chronic pain is frequently accompanied by anxiety and other affective disturbances, but the molecular and cellular changes linking peripheral injury to persistent alterations in brain function remain incompletely defined. The hippocampal extracellular matrix (ECM) regulates synaptic plasticity, cellular signaling, and neuroimmune interactions and may therefore contribute to pain-related central plasticity. We used a tibial fracture/cast immobilization model to examine temporal changes in hippocampal ECM, glial morphology, and affective behavior following peripheral injury. Behavioral testing was performed at 3, 7, and 20 weeks after injury, while high-dimensional morphometric analysis of microglia and astrocytes was performed at 1, 3, 7, and 20 weeks. Hippocampal ECM associated molecular signals were mapped at the chronic stage using decellularization coupled with MALDI-TOF mass spectrometry imaging. Injured mice developed mechanical hypersensitivity and reduced exploration in two anxiety related paradigms during the early and chronic stages, with these behavioral phenotypes no longer detected at 20 weeks. At 7 weeks, injury was associated with changes in hippocampal ECM-associated peptide signals, including reduced signals corresponding to four ECM-associated proteins. Microglia and astrocytes exhibited distinct, time-dependent changes in density and multidimensional morphology, with some alterations persisting after behavioral measures returned toward control levels. In vitro, BV2 microglia exhibited rigidity-dependent changes in morphology, phagocytic behavior, and calcium signaling. Together, these findings define a temporally evolving hippocampal ECM and glial phenotype following peripheral injury and identify matrix biomechanics as a candidate regulator of microglial function.

neuroscience↗

bioRxiv2026

Environmental control of morphological color changes in the Bigfin Reef Squid, Sepioteuthis lessoniana

Phenotypic plasticity enables organisms to adjust their traits in response to environmental conditions, yet studies of animal coloration--particularly in cephalopods--have largely focused on rapid neural control while overlooking slower, substrate-level changes. Here, we investigate whether morphological color change contributes to phenotypic plasticity in the bigfin reef squid (Sepioteuthis lessoniana). Hatchlings were reared in contrasting light (white) and dark (black) environments for 14 weeks, and chromatophore organization was quantified across developmental stages (4, 9, and 14 weeks) and body regions (dorsal and ventral) using high-resolution imaging and automated analysis. We find that environmental context and age interact to shape both the density and size of black, yellow, and red chromatophores, revealing a consistent trade-off between chromatophore number and expansion. Black-reared individuals maintain higher chromatophore densities, whereas white-reared individuals exhibit fewer but larger cells, particularly at later developmental stages. These effects are region-specific and align with the emergence of countershading, suggesting ecological tuning of pigmentation architecture. Our results demonstrate that the cellular substrate underlying color change is itself plastic and dynamically remodeled across development. We propose a hierarchical model in which slow morphological plasticity defines the functional limits of rapid neural color change. This work expands current frameworks of cephalopod coloration by integrating developmental, environmental, and cellular mechanisms, and highlights the importance of multi-timescale plasticity in adaptive visual signaling.

ecology↗

bioRxiv2025

Intersectional roles of trait covariation and phenotypic plasticity in the coloration and behavior of an African cichlid

An animals ability to adapt to a changing environment often requires the coordination of various traits. Across these traits, many covary with one another to generate a diversity of complex phenomes tuned to a given ecology. While many reports have documented trait covariation in populations, less is known about how plastic traits co-vary to facilitate adaptation in an individual. In African cichlids, morphology and behavior are two hallmarks driving the adaptive speciation of lineages within the East African Great Lakes. Here, we leverage social rank and body coloration as plastic model traits to understand the intersectional relationship shaping male competition in the African cichlid Astatotilapia burtoni. Addressing the need to disentangle the influence of environmental adaptation from social dynamics on color morphology, we conducted experiments rearing cichlids in visually distinct environments using blue and yellow gravel substrates to induce blue/yellow color morphs. Our results demonstrate that the visual environment significantly influences the emergence of male color morphs: yellow territorial males were more prevalent on brown gravel, whereas blue males predominantly appeared in blue backgrounds. Contrary to previous reports, we found that blue males consistently outcompete yellow males in direct contests. Furthermore, behavioral patterns changed over time, with blue males adjusting their aggression strategies based on their visual environment, while yellow males exhibited a higher propensity to flee. These findings indicate that animal coloration and behavior are intersectional plastic traits that interact to shape male competition and behavioral ecology. This study provides new insights into the dynamics of phenotypic plasticity, adaptive strategies in fluctuating environments, and trait covariation.

animal behavior and cognition↗

bioRxiv2025

Background color matching influences sexual behavior, growth, and mortality rate in an African cichlid fish

Phenotypic plasticity allows organisms to adapt to changing environments within their lifetimes. The cost of plastic adaptations may constrain the persistence of plasticity over evolutionary time. One potential cost is the possibility that phenotypic adjustment to specific environments can cause correlated responses that are not necessarily adaptive. Males in the African cichlid Astatotilapia burtoni are blue or yellow, and males are able adjust their body coloration to the color of the background, presumably to increase crypsis. To test whether background color influences fitness-related traits, we raised mix-sex groups of juvenile A. burtoni to adulthood in yellow or blue tanks. We found that fish in blue tanks were darker and more bluish, whereas fish reared in yellow tanks were paler and more yellow in body coloration. Males, but not females, from blue tanks showed earlier sexual maturation than those held in yellow tanks. However, across the duration of the experiment, there was a higher frequency of females mouthbrooding in groups housed in yellow tanks than those that were housed in blue tanks. In addition, fish in blue tanks exhibited reduced growth rate but higher survivorship relative to their yellow-reared counterparts. Our data suggests that background color affects important fitness-related traits in a color polymorphic cichlid, which may influence the evolution of phenotypic plasticity.

animal behavior and cognition↗

bioRxiv2024

Facial and body colouration are linked to social rank in the African cichlid, Astatotilapia burtoni

Animal colouration is fundamentally important for social communication within conspecifics to advertising threat to competitors or fitness to possible mates. Social status and animal colouration are covarying traits that are plastic in response to dynamic environments. In the African cichlid, Astatotilapia burtoni, body colouration and behaviour have been extensively reported to vary with social rank. However, the nature of the interaction between these two traits is poorly understood. We hypothesise that pigmentation patterns could be linked to the behavioural repertoires underlying social status and can be resolved to regions on the cichlid body plan. To test this hypothesis, we generated Territorial (T) and Non-territorial (NT) males and employed computer vision tools to quantify and visualise patterns/colour enrichment associated with stereotyped T/NT male behaviour. We report colour-behaviour interactions localised in specific areas of the body and face for two colour morphs illustrating a more nuanced view of social behaviour and pigmentation. Since behavioural and morphological variation are key drivers of selection in the East African Great Rift Lakes, we surmise our data may be translatable to other cichlid lineages and underline the importance of trait covariance in sexual selection and male competition.

animal behavior and cognition↗

bioRxiv2024

Effects of social position on subsequent courtship and mating activity in an African cichlid

Within social hierarchies, rank can be dynamic and modulated by changes in molecular and/or physiological substrates. Here, we sought to better understand how social environment and rank shape male spawning behaviors and outcomes in African cichlid fish Astatotilapia burtoni. First, using a social dyad paradigm, we generated territorial (T)/ Non-territorial (NT) male pairs. After establishing a stable social hierarchy, the behaviors of the Ts and NTs were recorded and scored. Afterward, pairs were separated and individually moved into a spawning phase, which consisted of a new tank with novel females and no other males where their behaviors were scored. While previous studies have shown how territorial and non-territorial males have unique behavioral profiles, we sought to deepen this interpretation with a focus on the latency of decision-making, and on transition matrices representing enriched sequences of behavior. We found that while the courtship behaviors are shared between stably territorial and ascending males in the spawning phase, only the animals that were territorial in the dyad phase were the ones that were reproductively successful in the subsequent 16 hour spawning phase.

animal behavior and cognition↗

bioRxiv2022

DNA methylation of the endothelin receptor B makes blue fish yellow

Natural selection shapes traits during evolution including animal coloration known to be important for concealment and communication and color has been particularly salient in the explosive radiation of cichlid fish species in the rift valley lakes of East Africa. Though selection can produce variation in color via genetic substrates during early development, plasticity in coloration can occur through endocrine, neural and transcriptional cues in response to various environmental stimuli. It is well known that some animals often change color to match their visual ecology. Adult male cichlid fish (Astatotilapia burtoni, Lake Tanganyika) can switch between blue and yellow body colors. Different colors result from the expression of pigment-bearing cells, which differ in density and function between these two color morphs. We show that A. burtoni switches from yellow to blue depending on their visual environment by downregulating endothelin receptor B (EdnRB) mRNA via DNA hypermethylation at a single cytosine residue within its promoter. EdnRB functions in yellow chromatophores to signal the aggregation of yellow pigments, making yellow less visible. Taken together, the regulation of EdnRB through DNA methylation in yellow chromatophores, in part, contributes to pigmentation changes from blue to yellow, depending on visual environment.

genetics↗