Biology subjects

Marchi, D.

Publications and source records attributed to Marchi, D..

4 recordsLinked to original sources

bioRxiv2025

The locomotor behavior of subfossil Malagasy sloth-lemurs (Strepsirrhini: Palaeopropithecidae) and koala-lemurs (Strepsirrhini: Megaladapidae): new insights from limb trabecular bone

The locomotion of Malagasy Quaternary subfossil lemurs--including palaeopropithecids ( sloth-lemurs) and megaladapids ( koala-lemurs)--has been investigated on abundant postcranial remains. Proposed strategies include some without living primate parallels, including sloth-like suspensory arboreality in palaeopropithecids, although the degree of suspensory behaviour in palaeopropithecids, or locomotor diversity in koala-lemurs are poorly understood. Differently from external morphology, internal bone structure in these taxa is largely unexplored. We compared the humeral and femoral trabecular architecture of sloth- and koala-lemurs to several extant mammals, studying spherical trabecular samples extracted from high-resolution scans. After defining locomotor categories from quantitative data, we tested links between trabecular parameters and locomotor modes through exploratory and multivariate analyses, accounting for body size and phylogeny. In extant mammals, only femoral trabecular traits--particularly Degree of Anisotropy and Bone Volume Fraction--were significantly associated with locomotion, distinguishing suspensory and bridging arboreal taxa from others. Using this model, we inferred suspensory adaptations in palaeopropithecids, especially Palaeopropithecus--confirming earlier reconstructions--but also in Megaladapis edwarsi, a striking result that would make M. edwarsi the largest mammal ever known to adopt such habits, approached only by extant orangutans. This work highlights the potential of internal bone structure for reconstructing primate locomotor evolution.

paleontology↗

bioRxiv2025

Early visual experience elicits cellular and functional plasticity in the retina and alters behaviour

Our interaction with the surrounding environment shapes how our brain processes sensory information and drives adaptive behaviour. This plasticity allows the brain to rewire in response to specific sensory experiences. For instance, early manipulation of visual inputs profoundly impacts brain plasticity, which is crucial for functions like size perception, object recognition, and visuospatial processing. While neuronal plasticity has been detected in visual target structures such as the colliculus, thalamus, and cortex, it remains unclear if the retina, the primary sensory organ, undergoes significant plasticity. Here, we show that the zebrafish retina demonstrates pronounced plastic transformations in response to alterations of the visual environment during development, which ultimately modifies the detection of oriented visual stimuli. We demonstrate that orientation-selective amacrine cells undergo profound morphological changes in animals exposed to distinct visual environments during development. We further find that the functional orientation-selective output from the retina is altered in a manner consistent with the visual environment in which the animals are raised and that these changes are persistent. Finally, animals tested in a virtual reality system show that early exposure to different visual environments changes their innate preference for specifically oriented patterns. Our findings unveil a unique developmental form of sensory organ plasticity with continuing structural and functional consequences.

neuroscience↗

bioRxiv2024

Buca della Iena and Grotta del Capriolo: new chronological, lithic, and faunal analyses of two late Mousterian sites in Central Italy

New radiocarbon, lithic, faunal, and documentary analyses of two sites, Buca della Iena and Grotta del Capriolo, excavated in the 1970s, enhance our understanding of late Neanderthal settlement in the northwestern Italian peninsula and provide insights into their demise. Reassessment of stratigraphical and fieldwork documentation identified areas of stratigraphic reliability, supporting robust interpretations. Radiocarbon dating reveals broadly contemporaneous occupations at both sites between 50-40 ka cal BP, with Buca della Iena showing occupation from approximately 47 to 42.5 ka cal BP. Lithic analyses demonstrate the consistent application of the same chaine operatoire across both sites. Faunal analyses indicate that carnivores, particularly Crocuta spelaea, were the dominant accumulating agents in Buca della Iena, while limited preservation at Grotta del Capriolo prevents detailed taxonomic determination. However, hominin presence at both sites is evidenced by cut-marked bones. This study provides new perspectives on the Middle-to- Upper Palaeolithic transition in the northwestern Italian peninsula.

paleontology↗

bioRxiv2019

Bidirectional crosstalk between HIF and Glucocorticoid signalling in zebrafish larvae

In the last decades in vitro studies highlighted the potential for crosstalk between Hypoxia-Inducible Factor-(HIF) and glucocorticoid-(GC) signalling pathways. However, how this interplay precisely occurs in vivo is still debated. Here, we use zebrafish larvae (Danio rerio) to elucidate how and to what degree hypoxic signalling affects the endogenous glucocorticoid pathway and vice versa, in vivo. Firstly, our results demonstrate that in the presence of upregulated HIF signalling, both glucocorticoid receptor (Gr) responsiveness and endogenous cortisol levels are repressed in 5 days post fertilisation larvae. In addition, despite HIF activity being low at normoxia, our data show that it already impedes both glucocorticoid activity and levels. Secondly, we further analysed the in vivo contribution of glucocorticoids to HIF activity. Interestingly, our results show that both glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) play a key role in enhancing it. Finally, we found indications that glucocorticoids promote HIF signalling via multiple routes. Cumulatively, our findings allowed us to suggest a model for how this crosstalk occurs in vivo. Author summaryHypoxia is a common pathophysiological condition to which cells must rapidly respond in order to prevent metabolic shutdown and subsequent death. This is achieved via the activity of Hypoxia-Inducible Factors (HIFs), which are key oxygen sensors that mediate the ability of the cell to cope with decreased oxygen levels. Although it aims to restore tissue oxygenation and perfusion, it can sometimes be maladaptive and contributes to a variety of pathological conditions including inflammation, tissue ischemia, stroke and growth of solid tumours. In this regard, synthetic glucocorticoids which are analogous to naturally occurring steroid hormones, have been used for decades as anti-inflammatory drugs for treating pathological conditions which are linked to hypoxia (i.e. asthma, rheumatoid arthritis, ischemic injury). Indeed, previous in vitro studies highlighted the presence of a crosstalk between HIF and glucocorticoids. However, how this interplay precisely occurs in an organism and what the molecular mechanism is behind it are questions that still remain unanswered. Here, we provide a thorough in vivo genetic analysis, which allowed us to propose a logical model of interaction between glucocorticoid and HIF signalling. In addition, our results are important because they suggest a new route to downregulate HIF for clinical purposes.

physiology↗