Evolution of the insect Sox genes

<p>Abstract</p> <p>Background</p> <p>The <it>Sox </it>gene family of transcriptional regulators have essential roles during development and have been extensively studied in vertebrates. The mouse, human and <it>fugu </it>genomes contain at least 20 <it>Sox </it>genes, which are subdivided into groups based on sequence similarity of the highly conserved HMG domain. In the well-studied insect <it>Drosophila melanogaster</it>, eight <it>Sox </it>genes have been identified and are involved in processes such as neurogenesis, dorsal-ventral patterning and segmentation.</p> <p>Results</p> <p>We examined the available genome sequences of <it>Apis mellifera, Nasonia vitripennis, Tribolium castaneum</it>, <it>Anopheles gambiae </it>and identified <it>Sox </it>family members which were classified by phylogenetics using the HMG domains. Using <it>in situ </it>hybridisation we determined the expression patterns of eight honeybee <it>Sox </it>genes in honeybee embryo, adult brain and queen ovary. <it>AmSoxB </it>group genes were expressed in the nervous system, brain and Malphigian tubules. The restricted localization of <it>AmSox21b </it>and <it>AmSoxB1 </it>mRNAs within the oocyte, suggested a role in, or that they are regulated by, dorsal-ventral patterning. <it>AmSoxC, D </it>and <it>F </it>were expressed ubiquitously in late embryos and in the follicle cells of the queen ovary. Expression of <it>AmSoxF </it>and two <it>AmSoxE </it>genes was detected in the drone testis.</p> <p>Conclusion</p> <p>Insect genomes contain between eight and nine <it>Sox </it>genes, with at least four members belonging to <it>Sox </it>group B and other <it>Sox </it>subgroups each being represented by a single <it>Sox </it>gene. Hymenopteran insects have an additional <it>SoxE </it>gene, which may have arisen by gene duplication. Expression analyses of honeybee <it>SoxB </it>genes implies that this group of genes may be able to rapidly evolve new functions and expression domains, while the combined expression pattern of all the <it>SoxB </it>genes is maintained.</p

Evolutionary origin and genomic organisation of runt-domain containing genes in arthropods

<p>Abstract</p> <p>Background</p> <p>Gene clusters, such as the <it>Hox </it>gene cluster, are known to have critical roles in development. In eukaryotes gene clusters arise primarily by tandem gene duplication and divergence. Genes within a cluster are often co-regulated, providing selective pressure to maintain the genome organisation, and this co-regulation can result in temporal or spatial co-linearity of gene expression. It has been previously noted that in <it>Drosophila melanogaster</it>, three of the four runt-domain (RD) containing genes are found in a relatively tight cluster on chromosome 1, raising the possibility of a putative functional RD gene cluster in <it>D. melanogaster</it>.</p> <p>Results</p> <p>To investigate the possibility of such a gene cluster, orthologues of the <it>Drosophila melanogaste</it>r RD genes were identified in several endopterygotan insects, two exopterygotan insects and two non-insect arthropods. In all insect species four RD genes were identified and orthology was assigned to the <it>Drosophila </it>sequences by phylogenetic analyses. Although four RD genes were found in the crustacean <it>D. pulex</it>, orthology could not be assigned to the insect sequences, indicating independent gene duplications from a single ancestor following the split of the hexapod lineage from the crustacean lineage.</p> <p>In insects, two chromosomal arrangements of these genes was observed; the first a semi-dispersed cluster, such as in <it>Drosophila</it>, where <it>lozenge </it>is separated from the core cluster of three RD genes often by megabases of DNA. The second arrangement was a tight cluster of the four RD genes, such as in <it>Apis mellifera</it>.</p> <p>This genomic organisation, particularly of the three core RD genes, raises the possibility of shared regulatory elements. <it>In situ </it>hybridisation of embryonic expression of the four RD genes in <it>Drosophila melanogaster </it>and the honeybee <it>A. mellifera </it>shows no evidence for either spatial or temporal co-linearity of expression during embryogenesis.</p> <p>Conclusion</p> <p>All fully sequenced insect genomes contain four RD genes and orthology can be assigned to these genes based on similarity to the <it>D. melanogaster </it>protein sequences. Examination of the genomic organisation of these genes provides evidence for a functional RD gene cluster. RD genes from non-insect arthropods are also clustered, however the lack of orthology between these and insect RD genes suggests this cluster is likely to have resulted from a duplication event independent from that which created the insect RD gene cluster. Analysis of embryonic RD gene expression in two endopterygotan insects, <it>A. mellifera </it>and <it>D. melanogaster</it>, did not show evidence for coordinated gene expression, therefore while the functional significance of this gene cluster remains unknown its maintenance during insect evolution implies some functional significance to the cluster.</p

Andean and Tibetan Patterns of Adaptation to High Altitude

Objectives: High-altitude hypoxia, or decreased oxygen levels caused by low barometric pressure, challenges the ability of humans to live and reproduce. Despite these challenges, human populations have lived on the Andean Altiplano and the Tibetan Plateau for millennia and exhibit unique circulatory, respiratory, and hematological adaptations to life at high altitude. We and others have identified natural selection candidate genes and gene regions for these adaptations using dense genome scan data. One gene previously known to be important in cellular oxygen sensing, egl nine homolog 1 (EGLN1), shows evidence of positive selection in both Tibetans and Andeans. Interestingly, the pattern of variation for this gene differs between the two populations. Continued research among Tibetan populations has identified statistical associations between hemoglobin concentration and single nucleotide polymorphism (SNP) genotype at EGLN1 and a second gene, endothelial PAS domain protein 1 (EPAS1). Methods: To measure for the effects of EGLN1 and EPAS1 altitude genotypes on hemoglobin concentration among Andean highlanders, we performed a multiple linear regression analysis of 10 candidate SNPs in or near these two genes. Results: Our analysis did not identify significant associations between EPAS1 or EGLN1 SNP genotypes and hemoglobin concentration in Andeans. Conclusions: These results contribute to our understanding of the unique set of adaptations developed in different highland groups to the hypoxia of high altitude. Overall, the results provide key insights into the patterns of genetic adaptation to high altitude in Andean and Tibetan populations

Review: Smokehouse Associates

Review of Smokehouse Associates by Eric Booker. Yale University Press, December 2022. 258 p. ill. ISBN 978-0-300-26720-4 (h/c), $55.00. https://yalebooks.yale.edu/book/9780300267204/smokehouse-associates/. Reviewed March 2023 by Kristen J. Owens, Librarian for African American and Black Diaspora Studies, New York University Libraries, Independent Curator, [email protected]

The atypical chemokine receptor Ackr2 constrains NK cell migratory activity and promotes metastasis

Chemokines have been shown to be essential players in a range of cancer contexts. In this study, we demonstrate that mice deficient in the atypical chemokine receptor Ackr2 display impaired development of metastasis in vivo in both cell line and spontaneous models. Further analysis reveals that this relates to increased expression of the chemokine receptor CCR2, specifically by KLRG1+ NK cells from the Ackr2−/− mice. This leads to increased recruitment of KLRG1+ NK cells to CCL2-expressing tumors and enhanced tumor killing. Together, these data indicate that Ackr2 limits the expression of CCR2 on NK cells and restricts their tumoricidal activity. Our data have important implications for our understanding of the roles for chemokines in the metastatic process and highlight Ackr2 and CCR2 as potentially manipulable therapeutic targets in metastasis