Pastelin-Palacios, R. | Search bioRxiv

bioRxiv2023

Splenocytes and thymocytes migration patterns between lymphoid organs in pregnancy

BackgroundCell migration is essential for the immune system, and frequently is analyzing in adult non-pregnant animals, and poorly explored in pregnancy, however, a physiologic increase of size in the spleen and periaortic lymph nodes had been reported in pregnant mice. MethodsUsing a mouse model, we transferred PKH26-stained thymocytes and splenocytes from pregnant or non-pregnant animals to receptor mice in the presence or absence of pregnancy. Percentage and Mean Fluorescence Intensity were calculated by Flow cytometry in pregnant or non-pregnant mice. Non-parametric ANOVA analysis was performed. ResultsWe detected that the percentage of PKH26+ thymocytes into the spleen, lymph nodes, and peripheral blood is higher in females than in males. Our results showed a similar frequency of thymocytes and splenocytes from pregnant and non-pregnant located into receptor lymphoid organs. Also, the location of marked cells was similar during the perinatal period. ConclusionsThe mobility of thymocytes and splenocytes in pregnant and non-pregnant mice is similar, therefore we suggest that the larger size of the spleen and periaortic lymph nodes noted previously in pregnant mice, could be the result of retention of leukocytes in the secondary lymphoid organs.

immunology↗

bioRxiv2022

Subfunctionalization and constrained size of the immunoglobulin loci in Ambystoma mexicanum

BackgroundThe axolotl, Ambystoma mexicanum is a unique biological model for complete tissue regeneration. Is a neotenic endangered species and is highly susceptible to environmental stress, including infectious disease. In contrast to other amphibians, the axolotl is particularly vulnerable to certain viral infections. Like other salamanders, the axolotl genome is one of the largest (32 Gb) and the impact of genome size on Ig loci architecture is unknown. To better understand the immune response in axolotl, we aimed to characterize the immunoglobulin loci of A. mexicanum and compare it with other model tetrapods. MethodsThe most recently published genome sequence of A. mexicanum (V6) was used for alignment-based annotation and manual curation using previously described axolotl Ig sequences or reference sequences from other tetrapods. Gene models were further curated using A. mexicanum spleen RNA-seq data. Human reference genomes, Xenopus tropicalis, and Danio rerio (zebrafish) were used for comparison. ResultsCanonical A. mexicanum Heavy chain (IGH), lambda (IGL), sigma (IGS) and Surrogate light chain (SLC) loci were identified. No kappa locus was found. More than half of the IGHV genes and the IGHF gene are pseudogenes, there are no clan I IGHV genes and CDRH3 diversity is restricted. Although the IGH locus size is proportional to genome size, we found local size restriction in the IGHM gene and in the V gene intergenic distances. In addition, there were V genes with abnormally large V-intron sizes, which correlated with loss of gene functionality. ConclusionThe A. mexicanum immunoglobulin loci share the same general genome architecture as most studied tetrapods. Consistent with its large genome, Ig loci are larger; however, local size restrictions indicate evolutionary constraints likely to be imposed by high transcriptional demand of certain Ig genes, as well as the V(D)J recombination over very long genomic distance ranges. The A. mexicanum has undergone an extensive process of pseudogenization which partially explains a reduced potential repertoire diversity that may contribute to its impaired antibody response.

immunology↗