scholarly journals Regressive evolution of the arthropod tritocerebral segment linked to functional divergence of the Hox gene labial

2015 ◽  
Vol 282 (1814) ◽  
pp. 20151162 ◽  
Author(s):  
Matthias Pechmann ◽  
Evelyn E. Schwager ◽  
Natascha Turetzek ◽  
Nikola-Michael Prpic
Keyword(s):  
Functional Divergence ◽  
Functional Change ◽  
Pleiotropic Effects ◽  
Limb Loss ◽  
Evolutionary Origin ◽  
Common Mechanism ◽  
Developmental Genes ◽  
Regressive Evolution ◽  
Hox Gene ◽  
Parasteatoda Tepidariorum

The intercalary segment is a limbless version of the tritocerebral segment and is present in the head of all insects, whereas other extant arthropods have retained limbs on their tritocerebral segment (e.g. the pedipalp limbs in spiders). The evolutionary origin of limb loss on the intercalary segment has puzzled zoologists for over a century. Here we show that an intercalary segment-like phenotype can be created in spiders by interfering with the function of the Hox gene labial . This links the origin of the intercalary segment to a functional change in labial . We show that in the spider Parasteatoda tepidariorum the labial gene has two functions: one function in head tissue maintenance that is conserved between spiders and insects, and a second function in pedipalp limb promotion and specification, which is only present in spiders. These results imply that labial was originally crucial for limb formation on the tritocerebral segment, but that it has lost this particular subfunction in the insect ancestor, resulting in limb loss on the intercalary segment. Such loss of a subfunction is a way to avoid adverse pleiotropic effects normally associated with mutations in developmental genes, and may thus be a common mechanism to accelerate regressive evolution.

scholarly journals Recurrent functional divergence of early tetrapod keratins in amphibian toe pads and mammalian hair

2013 ◽  
Vol 9 (3) ◽  
pp. 20130051 ◽  
Author(s):  
Wim Vandebergh ◽  
Margo Maex ◽  
Franky Bossuyt ◽  
Ines Van Bocxlaer
Keyword(s):  
Cdna Library ◽  
Phylogenetic Analyses ◽  
Functional Divergence ◽  
Cytoskeletal Proteins ◽  
Evolutionary Origin ◽  
Structural Proteins ◽  
Tree Frog ◽  
Hyla Cinerea ◽  
Early Tetrapods ◽  
Mammalian Hair

Amphibians have invaded arboreal habitats multiple times independently during their evolution. Adaptation to these habitats was nearly always accompanied by the presence or appearance of toe pads, flattened enlargements on tips of fingers and toes that provide adhesive power in these environments. The strength and elasticity of the toe pad relies on polygonal arrayed cells ending in nanoscale projections, which are densely packed with cytoskeletal proteins. Here, we characterized and determined the evolutionary origin of these proteins in the toe pad of the tree frog Hyla cinerea . We created a subtracted cDNA library enriching genes that are expressed in the toe pad, but nowhere else in the toe. Our analyses revealed five alpha keratins as main structural proteins of the amphibian toe pad. Phylogenetic analyses show that these proteins belong to different keratin lineages that originated in an early tetrapod ancestor and in mammals evolved to become the major keratin types of hair. The ancestral keratins were probably already expressed in areas that required skin reinforcement in early tetrapods, and subsequently diverged to support fundamentally different adaptive structures in amphibians and mammals.

scholarly journals A conserved genetic mechanism specifies deutocerebral appendage identity in insects and arachnids

2015 ◽  
Vol 282 (1808) ◽  
pp. 20150698 ◽  
Author(s):  
Prashant P. Sharma ◽  
Oscar A. Tarazona ◽  
Davys H. Lopez ◽  
Evelyn E. Schwager ◽  
Martin J. Cohn ◽  
...  
Keyword(s):  
Hox Genes ◽  
Fruit Fly ◽  
Evolutionary Developmental Biology ◽  
Common Mechanism ◽  
Gryllus Bimaculatus ◽  
Hox Gene ◽  
Fate Specification ◽  
Deep Homology ◽  
Pair Of Antennae ◽  
Appendage Patterning

The segmental architecture of the arthropod head is one of the most controversial topics in the evolutionary developmental biology of arthropods. The deutocerebral (second) segment of the head is putatively homologous across Arthropoda, as inferred from the segmental distribution of the tripartite brain and the absence of Hox gene expression of this anterior-most, appendage-bearing segment. While this homology statement implies a putative common mechanism for differentiation of deutocerebral appendages across arthropods, experimental data for deutocerebral appendage fate specification are limited to winged insects. Mandibulates (hexapods, crustaceans and myriapods) bear a characteristic pair of antennae on the deutocerebral segment, whereas chelicerates (e.g. spiders, scorpions, harvestmen) bear the eponymous chelicerae. In such hexapods as the fruit fly, Drosophila melanogaster , and the cricket, Gryllus bimaculatus , cephalic appendages are differentiated from the thoracic appendages (legs) by the activity of the appendage patterning gene homothorax ( hth ). Here we show that embryonic RNA interference against hth in the harvestman Phalangium opilio results in homeonotic chelicera-to-leg transformations, and also in some cases pedipalp-to-leg transformations. In more strongly affected embryos, adjacent appendages undergo fusion and/or truncation, and legs display proximal defects, suggesting conservation of additional functions of hth in patterning the antero-posterior and proximo-distal appendage axes. Expression signal of anterior Hox genes labial , proboscipedia and Deformed is diminished, but not absent, in hth RNAi embryos, consistent with results previously obtained with the insect G. bimaculatus . Our results substantiate a deep homology across arthropods of the mechanism whereby cephalic appendages are differentiated from locomotory appendages.

scholarly journals The role of structural pleiotropy and regulatory evolution in the retention of heteromers of paralogs

2019 ◽  
Author(s):  
Axelle Marchant ◽  
Angel F. Cisneros ◽  
Alexandre K Dubé ◽  
Isabelle Gagnon-Arsenault ◽  
Diana Ascencio ◽  
...  
Keyword(s):  
Protein Localization ◽  
Functional Divergence ◽  
Interaction Network ◽  
Pleiotropic Effects ◽  
Regulatory Evolution ◽  
Protein Protein Interaction ◽  
Genes Encoding ◽  
Duplication Events ◽  
Highly Correlated

AbstractMany paralogs derive from the duplication of genes encoding homomeric proteins. Such duplication events lead to the formation of homomers and heteromers, thus creating new structures from a single event. We exhaustively characterize this phenomenon using the budding yeast protein-protein interaction network. We observe that paralogs that heteromerize are very frequent and less functionally diverged than those that lost this property, raising the possibility that heteromerization prevents functional divergence. Using in silico evolution, we show that for homomers and heteromers that share binding interfaces, mutations on one complex have pleiotropic effects on the other complex, resulting in highly correlated responses to selection. As a result, heteromerization could be preserved indirectly due to selection for the maintenance of homomers. By integrating data on gene expression and protein localization, we find that regulatory evolution could play a role in overcoming these structural pleiotropic effects and in allowing paralog functional divergence.

scholarly journals Evolutionary origin and functional divergence of totipotent cell homeobox genes in eutherian mammals

BMC Biology ◽  
2016 ◽  
Vol 14 (1) ◽  
Author(s):  
Ignacio Maeso ◽  
Thomas L. Dunwell ◽  
Chris D. R. Wyatt ◽  
Ferdinand Marlétaz ◽  
Borbála Vető ◽  
...  
Keyword(s):  
Functional Divergence ◽  
Homeobox Genes ◽  
Evolutionary Origin ◽  
Totipotent Cell

scholarly journals Developmental Genes Have Pleiotropic Effects on Plant Morphology and Source Capacity, Eventually Impacting on Seed Protein Content and Productivity in Pea

2007 ◽  
Vol 144 (2) ◽  
pp. 768-781 ◽  
Author(s):  
Judith Burstin ◽  
Pascal Marget ◽  
Myriam Huart ◽  
Annie Moessner ◽  
Brigitte Mangin ◽  
...  
Keyword(s):  
Protein Content ◽  
Seed Protein ◽  
Plant Morphology ◽  
Pleiotropic Effects ◽  
Seed Protein Content ◽  
Developmental Genes

SHORT INTEGUMENTS 2 Promotes Growth During Arabidopsis Reproductive Development

Genetics ◽  
2000 ◽  
Vol 155 (2) ◽  
pp. 899-907
Author(s):  
Jean Broadhvest ◽  
Shawn C Baker ◽  
Charles S Gasser
Keyword(s):  
Cell Division ◽  
Cell Expansion ◽  
Double Mutant ◽  
Reproductive Development ◽  
Flower Morphology ◽  
Genetic Interactions ◽  
Pleiotropic Effects ◽  
Evolutionary Origin ◽  
Morphological Development ◽  
Primary Role

Abstract The short integuments 2 (sin2) mutation arrests cell division during integument development of the Arabidopsis ovule and also has subtle pleiotropic effects on both sepal and pistil morphology. Genetic interactions between sin2 and other ovule mutations show that cell division, directionality of growth, and cell expansion represent at least partially independent processes during integument development. Double-mutant analyses also reveal that SIN2 shares functional redundancy with HUELLENLOS in ovule primordium outgrowth and proximal-distal patterning and with TSO1 in promotion of normal morphological development of the four whorls of primary floral organs. All of these observations are consistent with SIN2 being a promoter of growth and cell division during reproductive development, with a primary role in these processes during integument development. On the basis of the floral pleiotropic effects observed in a majority of ovule mutants, including sin2, we postulate a relationship between ovule genes and the evolutionary origin of some processes regulating flower morphology.

scholarly journals A chromosome-level Camptotheca acuminata genome assembly provides insights into the evolutionary origin of camptothecin biosynthesis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Minghui Kang ◽  
Rao Fu ◽  
Pingyu Zhang ◽  
Shangling Lou ◽  
Xuchen Yang ◽  
...  
Keyword(s):  
Genome Assembly ◽  
Malignant Tumors ◽  
Functional Divergence ◽  
Camptotheca Acuminata ◽  
Evolutionary Origin ◽  
High Quality ◽  
Genetic Changes ◽  
Positive Evolution ◽  
High Quality Genome ◽  
Chromosome Level

AbstractCamptothecin and its derivatives are widely used for treating malignant tumors. Previous studies revealed only a limited number of candidate genes for camptothecin biosynthesis in Camptotheca acuminata, and it is still poorly understood how its biosynthesis of camptothecin has evolved. Here, we report a high-quality, chromosome-level C. acuminata genome assembly. We find that C. acuminata experiences an independent whole-genome duplication and numerous genes derive from it are related to camptothecin biosynthesis. Comparing with Catharanthus roseus, the loganic acid O-methyltransferase (LAMT) in C. acuminata fails to convert loganic acid into loganin. Instead, two secologanic acid synthases (SLASs) convert loganic acid to secologanic acid. The functional divergence of the LAMT gene and positive evolution of two SLAS genes, therefore, both contribute greatly to the camptothecin biosynthesis in C. acuminata. Our results emphasize the importance of high-quality genome assembly in identifying genetic changes in the evolutionary origin of a secondary metabolite.

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