Biology subjects

Marzal, A.

Publications and source records attributed to Marzal, A..

3 recordsLinked to original sources

bioRxiv2025

Generalist malaria parasites and host imprinting: Unveiling transcriptional memory

Generalist parasites must rapidly adapt to diverse host environments to ensure their survival and transmission. Parasites may employ fixed genetic responses, transcriptional plasticity, or epigenetic mechanisms to optimize survival. The avian malaria parasite Plasmodium homocircumflexum serves as an ideal model for studying transcriptional variation and adaptive strategies. We experimentally inoculated P. homocircumflexum into different bird hosts, bypassing vector recombination, to investigate whether parasite gene expression remains stable across hosts, resets in response to new environments, or reflects epigenetic inheritance. Our study evaluates four potential mechanisms: (1) A universal gene expression profile ("one key fits all"), where expression remains stable across hosts. Our outcomes revealed that gene expression differed significantly depending on the host species and time post-infection, thus rejecting this hypothesis. (2) Complete transcriptional plasticity, where gene expression is fully determined by the recipient host. Contrary to this hypothesis, we observed that gene expression was primarily influenced by the donor at 8 days post-infection (dpi), whereas gene expression was more aligned with the recipient host at 16 dpi. (3) Epigenetic inheritance, where early-stage gene expression reflects the donor host but gradually adjusts to the recipient. Our results support this mechanism, as 2,647 differentially expressed genes (DEGs) were associated with donors at 8 dpi, whereas 271 DEGs were linked to the recipient by 16 dpi. (4) Selection-driven differentiation favoring specific haplotypes. This latter hypothesis was not supported since SNP analyses showed low genetic differentiation. These findings suggest a P. homocircumflexum transition from donor-dependent to recipient-dependent gene expression, likely mediated by epigenetic regulation and transcriptional plasticity.

genomics↗

bioRxiv2021

Extensive transgressive gene expression in a homoploid hybrid species

Hybridization can result in novel allelic combinations which can impact the hybrid phenotype through changes in gene expression. While mis-expression in F1 hybrids is well documented, how gene expression evolves in stabilized hybrid taxa remains an open question. As gene expression evolves in a stabilizing manner, break-up of co-evolved cis- and trans-regulatory elements could lead to transgressive patterns of gene expression in hybrids. Here, we address to what extent gonad gene expression has evolved in an established and stable homoploid hybrid, the Italian sparrow (Passer italiae). Through comparison of gene expression in gonads from individuals of the two parental species (i.e., house and Spanish sparrow) to that of Italian sparrows, we find evidence for strongly transgressive expression in male Italian sparrows - 22% of testis genes exhibit expression patterns outside the range of both parent species. In contrast, Italian sparrow ovary expression was similar to that of one of the parent species, the house sparrow (Passer domesticus). Moreover, the Italian sparrow testis transcriptome is 26 times as diverged from those of the parent species as the parental transcriptomes are from each other, despite being genetically intermediate. This highlights the potential for regulation of gene expression to produce novel variation following hybridization. Genes involved in mitochondrial respiratory chain complexes and protein synthesis are enriched in the subset that is over-dominantly expressed in Italian sparrow testis, suggesting that selection on key functions have molded the hybrid Italian sparrow transcriptome.

evolutionary biology↗

bioRxiv2018

Host-parasite interaction explains variation in prevalence of avian haemosporidians at the community level

Parasites are a selective force that shape host community structure and dynamics, but host communities can also influence parasitism. Understanding the dual nature from host-parasite interactions can be facilitated by quantifying the variation in parasite prevalence (i.e. the proportion of infected host individuals in a population) among host species and then comparing that variation to other ecological factors that are known to also shape host communities. Avian haemosporidian parasites (e.g. Plasmodium and Haemoproteus) are abundant and widespread representing an excellent model for the study of host-parasite interactions. Several geographic and environmental factors have been suggested to determine prevalence of avian haemosporidians in bird communities. However, much remains to be known regarding whether host and parasite traits, represented by phylogenetic distances among species and degree of specialization in host-parasite relationships, can influence parasite prevalence. The aims of this study were to analyze factors affecting prevalence in a bird community and to test whether the degree of parasite specialization on their hosts is determined by host traits. Our statistical analyses suggest that prevalence is mainly determined by the interaction between host species and parasite lineages where tolerance and/or susceptibility to parasites plays an essential role. Additionally, we found that although some of the parasite lineages infected a low number of bird species, the species they infected were distantly related and therefore the parasites themselves should not be considered typical host specialists. Prevalence was higher for generalist than for specialist parasites in some, but not all, host species. These results suggest that prevalence mainly results from the interaction between host immune defences and parasite exploitation strategies wherein the result of an association between particular parasite lineages and particular host species is idiosyncratic.

ecology↗