scholarly journals Hox genes limit germ cell formation in the short germ insect Gryllus bimaculatus

2018 ◽  
Author(s):  
Austen A. Barnett ◽  
Taro Nakamura ◽  
Cassandra G. Extavour
Keyword(s):  
Hox Genes ◽  
Primordial Germ Cells ◽  
Cell Formation ◽  
Gryllus Bimaculatus ◽  
Sex Combs Reduced ◽  
Body Regions ◽  
Sex Combs ◽  
Hemimetabolous Insect ◽  
Encoding Genes ◽  
Germ Cell Formation

AbstractHox genes are conserved transcription factor-encoding genes that specify the identity of body regions in bilaterally symmetrical animals. In the cricket Gryllus bimaculatus, a member of the hemimetabolous insect group Orthoptera, the induction of a subset of mesodermal cells to form the primordial germ cells (PGCs) is restricted to the second through the fourth abdominal segments (A2-A4). In numerous insect species, the Hox genes Sex-combs reduced (Scr), Antennapedia (Antp), Ultrabithorax (Ubx) and abdominal-A (abd-A) jointly regulate the identities of middle and posterior body segments, suggesting that these genes may restrict PGC formation to specific abdominal segments in G. bimaculatus. Here we show that all of these Hox genes, either individually or in segment-specific combinations, restrict PGC formation. Our data provides evidence for a segmental Hox code used to regulate the placement of PGC formation, reminiscent of the segmental Hox codes used in other arthropod groups to establish other aspects of segmental identity. These data also provide, to our knowledge, the first evidence for this ancient group of genes in determining PGC placement within the context of axial patterning in any animal studied thus far.

scholarly journals Hox genes limit germ cell formation in the short germ insect Gryllus bimaculatus

2019 ◽  
Vol 116 (33) ◽  
pp. 16430-16435
Author(s):  
Austen A. Barnett ◽  
Taro Nakamura ◽  
Cassandra G. Extavour
Keyword(s):  
Hox Genes ◽  
Primordial Germ Cells ◽  
Cell Formation ◽  
Gryllus Bimaculatus ◽  
Sex Combs Reduced ◽  
Body Regions ◽  
Sex Combs ◽  
Hemimetabolous Insect ◽  
Encoding Genes

Hox genes are conserved transcription factor-encoding genes that specify the identity of body regions in bilaterally symmetrical animals. In the cricket Gryllus bimaculatus, a member of the hemimetabolous insect group Orthoptera, the induction of a subset of mesodermal cells to form the primordial germ cells (PGCs) is restricted to the second through the fourth abdominal segments (A2 to A4). In numerous insect species, the Hox genes Sex-combs reduced (Scr), Antennapedia (Antp), Ultrabithorax (Ubx), and abdominal-A (abd-A) jointly regulate the identities of middle and posterior body segments, suggesting that these genes may restrict PGC formation to specific abdominal segments in G. bimaculatus. Here we show that reducing transcript levels of some or all of these Hox genes results in supernumerary and/or ectopic PGCs, either individually or in segment-specific combinations, suggesting that the role of these Hox genes is to limit PGC development with respect to their number, segmental location, or both. These data provide evidence of a role for this ancient group of genes in PGC development.

Sequence of the Tribolium castaneum Homeotic Complex: The Region Corresponding to the Drosophila melanogaster Antennapedia Complex

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 1067-1074
Author(s):  
Susan J Brown ◽  
John P Fellers ◽  
Teresa D Shippy ◽  
Elizabeth A Richardson ◽  
Mark Maxwell ◽  
...  
Keyword(s):  
Tribolium Castaneum ◽  
Hox Genes ◽  
Transcription Unit ◽  
Sex Combs Reduced ◽  
Sex Combs ◽  
Selector Genes ◽  
Homeotic Selector Genes ◽  
Encoding Genes ◽  
Single Cluster ◽  
Homeotic Selector

Abstract The homeotic selector genes of the red flour beetle, Tribolium castaneum, are located in a single cluster. We have sequenced the region containing the homeotic selector genes required for proper development of the head and anterior thorax, which is the counterpart of the ANTC in Drosophila. This 280-kb interval contains eight homeodomain-encoding genes, including single orthologs of the Drosophila genes labial, proboscipedia, Deformed, Sex combs reduced, fushi tarazu, and Antennapedia, as well as two orthologs of zerknüllt. These genes are all oriented in the same direction, as are the Hox genes of amphioxus, mice, and humans. Although each transcription unit is similar to its Drosophila counterpart in size, the Tribolium genes contain fewer introns (with the exception of the two zerknüllt genes), produce shorter mRNAs, and encode smaller proteins. Unlike the ANTC, this region of the Tribolium HOMC contains no additional genes.

Analysis of Drosophila proboscipedia mutant alleles

Genome ◽  
2004 ◽  
Vol 47 (3) ◽  
pp. 600-609 ◽  
Author(s):  
I Tayyab ◽  
H M Hallahan ◽  
A Percival-Smith
Keyword(s):  
Dna Sequence ◽  
Hox Genes ◽  
Genetic Interaction ◽  
Direct Interaction ◽  
Protein Product ◽  
Maxillary Palp ◽  
Phenotypic Analysis ◽  
Sex Combs Reduced ◽  
Important Region ◽  
Sex Combs

Proboscipedia (PB) is a HOX protein required for adult maxillary palp and proboscis formation. To identify domains of PB important for function, 21 pb point mutant alleles were sequenced. Twelve pb alleles had DNA sequence changes that encode an altered PB protein product. The DNA sequence changes of these 12 alleles fell into 2 categories: missense alleles that effect the PB homeodomain (HD), and nonsense or frameshift alleles that result in C-terminal truncations of the PB protein. The phenotypic analysis of the pb homeobox missense alleles suggests that the PB HD is required for maxillary palp and proboscis development and pb – Sex combs reduced (Scr) genetic interaction. The phenotypic analysis of the pb nonsense or frameshift alleles suggests that the C-terminus is an important region required for maxillary palp and proboscis development and pb–Scr genetic interaction. PB and SCR do not interact directly with one another in a co-immunoprecipitation assay and in a yeast two-hybrid analysis, which suggests the pb–Scr genetic interaction is not mediated by a direct interaction between PB and SCR.Key words: proboscipedia, Sex combs reduced, Hox genes, mutant analysis, Drosophila body plan, appendage development.

scholarly journals Hox genes mediate the escalation of sexually antagonistic traits in water striders

2019 ◽  
Vol 15 (2) ◽  
pp. 20180720 ◽  
Author(s):  
Antonin Jean Johan Crumière ◽  
Abderrahman Khila
Keyword(s):  
Sexual Conflict ◽  
Hox Genes ◽  
Complete Loss ◽  
Water Strider ◽  
Fitness Costs ◽  
Sex Combs Reduced ◽  
Hox Gene ◽  
Water Striders ◽  
Sex Combs ◽  
Sex Comb

Sexual conflict occurs when traits favoured in one sex impose fitness costs on the other sex. In the case of sexual conflict over mating rate, the sexes often undergo antagonistic coevolution and escalation of traits that enhance females' resistance to superfluous mating and traits that increase males' persistence. How this escalation in sexually antagonistic traits is established during ontogeny remains unclear. In the water strider Rhagovelia antilleana, male persistence traits consist of sex combs on the forelegs and multiple rows of spines and a thick femur in the rear legs. Female resistance traits consist of a prominent spike-like projection of the pronotum. RNAi knockdown against the Hox gene Sex Combs Reduced resulted in the reduction in both the sex comb in males and the pronotum projection in females. RNAi against the Hox gene Ultrabithorax resulted in the complete loss or reduction of all persistence traits in male rear legs. These results demonstrate that Hox genes can be involved in intra- and inter-locus sexual conflict and mediate escalation of sexually antagonistic traits.

Stage-sensitivity and dose—response curve of u.v. effect on germ cell formation in embryos of Xenopus laevis

Development ◽  
1976 ◽  
Vol 35 (3) ◽  
pp. 617-623
Author(s):  
Ken-Ichi Ijiri
Keyword(s):  
Xenopus Laevis ◽  
Germ Cell ◽  
Dose Response ◽  
Response Curve ◽  
Developmental Stages ◽  
Primordial Germ Cells ◽  
Cell Formation ◽  
Dose Response Curve ◽  
Quantitative Studies ◽  
Germ Cell Formation

Ultraviolet light (u.v.) irradiation of the vegetal hemisphere of Xenopus laevis eggs resulted in the elimination of primordial germ cells in tadpoles. Quantitative studies were performed on this phenomenon. The stage sensitivity to u.v. in activation of germ cell formation was obtained for the early developmental stages ranging from immediately after fertilization to small cell blastula. It was found that u.v. irradiation at the stage immediately after fertilization was more injurious than irradiation at the beginning of the first cleavage. After deciding optimal conditions for this u.v. irradiation experiment, a dose-response curve of the phenomenon was obtained. It showed a good agreement with the theoretical expectation, which the authors had previously presented.

TheDrosophilaproboscis is specified by two Hox genes,proboscipediaandSex combs reduced, via repression of leg and antennal appendage genes

Development ◽  
2001 ◽  
Vol 128 (14) ◽  
pp. 2803-2814 ◽  
Author(s):  
Arhat Abzhanov ◽  
Stacy Holtzman ◽  
Thomas C. Kaufman
Keyword(s):  
Limb Development ◽  
Hox Genes ◽  
Distinct Type ◽  
Wild Type ◽  
Fate Map ◽  
Genetic Studies ◽  
Unique Type ◽  
Sex Combs Reduced ◽  
Sex Combs ◽  
Labial Disc

The proboscis is one of the most highly modified appendages in Drosophila melanogaster. However, the phenotypes of proboscipedia (pb) mutants, which transform the proboscis into leg or antenna, indicate a basic homology among these limbs. Recent genetic studies have revealed a developmental system for patterning appendages and identified several genes required for limb development. Among these are: extradenticle (exd), homothorax (hth), dachshund (dac), Distal-less (Dll) and spalt (sal). These limb genes have not been well studied in wild-type mouthparts and their role if any in this appendage is not well understood. Here we demonstrate that the homeotic gene products Proboscipedia (Pb) and Sex combs reduced (Scr) regulate the limb genes in the labial disc to give rise to a unique type of appendage, the proboscis. Pb inhibits exd, dac and sal expression and downregulates Dll. This observation explains the ability of Pb to inhibit the effects of ectopically expressed trunk Hox genes in the proboscis, to suppress leg identity in the trunk and to transform antenna to maxillary palp. Scr suppresses sal expression and also downregulates Dll in the labial discs; discs mutant for both pb and Scr give rise to complete antennae, further demonstrating appendage homology. In the labial disc, Pb positively regulates transcription of Scr, whereas in the embryo, Scr positively regulates pb. Additionally, our results suggests a revised fate map of the labial disc. We conclude that the proboscis constitutes a genetically distinct type of appendage whose morphogenesis does not require several important components of leg and/or antennal patterning systems, but retains distal segmental homology with these appendages.

Distinct roles of retinoic acid and BMP4 pathways in the formation of chicken primordial germ cells and spermatogonial stem cells

2019 ◽  
Vol 10 (11) ◽  
pp. 7152-7163 ◽  
Author(s):  
Qisheng Zuo ◽  
Jing Jin ◽  
Kai Jin ◽  
Changhua Sun ◽  
Jiuzhou Song ◽  
...  
Keyword(s):  
Stem Cells ◽  
Retinoic Acid ◽  
Germ Cell ◽  
Bone Morphogenetic Protein ◽  
Germ Cells ◽  
Primordial Germ Cells ◽  
Cell Formation ◽  
Bone Morphogenetic Protein 4 ◽  
Morphogenetic Protein ◽  
Germ Cell Formation

This study demonstrated different effects of bone morphogenetic protein 4 (BMP4) and retinoic acid (RA) signaling on the induction of germ cell formation in chickens.

scholarly journals The genome of a daddy-long-legs (Opiliones) illuminates the evolution of arachnid appendages

2021 ◽  
Vol 288 (1956) ◽  
pp. 20211168
Author(s):  
Guilherme Gainett ◽  
Vanessa L. González ◽  
Jesús A. Ballesteros ◽  
Emily V. W. Setton ◽  
Caitlin M. Baker ◽  
...  
Keyword(s):  
Genetic Basis ◽  
Hox Genes ◽  
Genome Duplication ◽  
Draft Genome ◽  
Growth Factor Receptor ◽  
Loss Of Function ◽  
Sex Combs Reduced ◽  
Sex Combs ◽  
Dynamic Genome ◽  
Epidermal Growth

Chelicerate arthropods exhibit dynamic genome evolution, with ancient whole-genome duplication (WGD) events affecting several orders. Yet, genomes remain unavailable for a number of poorly studied orders, such as Opiliones (daddy-long-legs), which has hindered comparative study. We assembled the first harvestman draft genome for the species Phalangium opilio , which bears elongate, prehensile appendages, made possible by numerous distal articles called tarsomeres. Here, we show that the genome of P. opilio exhibits a single Hox cluster and no evidence of WGD. To investigate the developmental genetic basis for the quintessential trait of this group—the elongate legs—we interrogated the function of the Hox genes Deformed ( Dfd ) and Sex combs reduced ( Scr ), and a homologue of Epidermal growth factor receptor ( Egfr ). Knockdown of Dfd incurred homeotic transformation of two pairs of legs into pedipalps, with dramatic shortening of leg segments in the longest leg pair, whereas homeosis in L3 is only achieved upon double Dfd + Scr knockdown. Knockdown of Egfr incurred shortened appendages and the loss of tarsomeres. The similarity of Egfr loss-of-function phenotypic spectra in insects and this arachnid suggest that repeated cooption of EGFR signalling underlies the independent gains of supernumerary tarsomeres across the arthropod tree of life.

RNAi analysis of Deformed, proboscipedia and Sex combs reduced in the milkweed bug Oncopeltus fasciatus: novel roles for Hox genes in the hemipteran head

Development ◽  
2000 ◽  
Vol 127 (17) ◽  
pp. 3683-3694 ◽  
Author(s):  
C.L. Hughes ◽  
T.C. Kaufman
Keyword(s):  
Expression Pattern ◽  
Gene Function ◽  
Hox Genes ◽  
Genetic Model ◽  
Oncopeltus Fasciatus ◽  
The Other ◽  
Regulatory Control ◽  
Sex Combs Reduced ◽  
Milkweed Bug ◽  
Sex Combs

Insects have evolved a large variety of specialized feeding strategies, with a corresponding variability in mouthpart morphology. We have, however, little understanding of the developmental mechanisms that underlie this diversity. Until recently it was difficult to perform any analysis of gene function outside of the genetic model insects Drosophila melanogaster and Tribolium castaneum. In this paper, we report the use of dsRNA-mediated interference (RNAi) to dissect gene function in the development of the milkweed bug Oncopeltus fasciatus, which has specialized suctorial mouthparts. The Hox genes Deformed (Dfd), proboscipedia (pb) and Sex combs reduced (Scr) have previously been shown to be expressed in the gnathal appendages of this species. Strikingly, the milkweed bug was found to have an unusual expression pattern of pb. Here, by analyzing single and combination RNAi depletions, we find that Dfd, pb and Scr are used in the milkweed bug to specify the identity of the mouthparts. The exact roles of the genes, however, are different from what is known in the two genetic model insects. The maxillary appendages in the bug are determined by the activities of the genes Dfd and Scr, rather than Dfd and pb as in the fly and beetle. The mandibular appendages are specified by Dfd, but their unique morphology in Oncopeltus suggests that Dfd's target genes are different. As in flies and beetles, the labium is specified by the combined activities of pb and Scr, but again, the function of pb appears to be different. Additionally, the regulatory control of pb by the other two genes seems to be different in the bug than in either of the other species. These novelties in Hox function, expression pattern and regulatory relationships may have been important for the evolution of the unique Hemipteran head.

scholarly journals Hox genes mediate the escalation of sexually antagonistic traits in water striders

2018 ◽  
Author(s):  
Antonin Jean Johan Crumière ◽  
Abderrahman Khila
Keyword(s):  
Sexual Conflict ◽  
Hox Genes ◽  
The Body ◽  
Water Strider ◽  
Fitness Costs ◽  
Sex Combs Reduced ◽  
Hox Gene ◽  
Sex Combs ◽  
Sex Comb ◽  
Resistance Trait

AbstractSexual conflict occurs when traits favoured in one sex impose fitness costs on the other sex. In the case of sexual conflict over mating rate, the sexes often undergo antagonistic coevolution and escalation of traits that enhance female’s resistance to mating and traits that increase male’s persistence. How this escalation in sexually antagonistic traits is established during ontogeny remains unclear. In the water strider Rhagovelia antilleana, male persistence traits consist of sex combs in the forelegs and multiple rows of spines and a thick femur in the rearlegs. Female resistance trait consists of a prominent spike-like projection of the pronotum. RNAi knockdown against the Hox gene Sex Combs Reduced resulted in the reduction of both the sex comb in males and the pronotum projection in females. RNAi against the Hox gene Ultrabithorax resulted in the complete loss or reduction of all persistence traits in male rearlegs. These results demonstrate that Hox genes can mediate sex-specific escalation of antagonistic traits along the body axis of both sexes.

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