scholarly journals Insect wings and body wall evolved from ancient leg segments

2018 ◽  
Author(s):  
Heather S. Bruce ◽  
Nipam H. Patel
Keyword(s):  
Functional Data ◽  
Body Wall ◽  
Gene Knockout ◽  
The Body ◽  
Ancestral State ◽  
Gap Genes ◽  
Insect Wings ◽  
Patterning Genes ◽  
Novel Structures ◽  
Do So

AbstractThe origin of insect wings has long been debated. Central to this debate is whether wings evolved from an epipod (outgrowth, e.g., a gill) on ancestral crustacean leg segments, or represent a novel outgrowth from the dorsal body wall that co-opted some of the genes used to pattern the epipods. To determine whether wings can be traced to ancestral, pre-insect structures, or arose by co-option, comparisons are necessary between insects and arthropods more representative of the ancestral state, where the hypothesized proximal leg region is not fused to the body wall. To do so, we examined the function of five leg patterning genes in the crustacean Parhyale hawaiensis and compared this to previous functional data from insects. By comparing gene knockout phenotypes of leg patterning genes in a crustacean with those of insects, we show that two ancestral crustacean leg segments were incorporated into the insect body, moving the leg’s epipod dorsally, up onto the back to form insect wings. Thus, our data shows that much of the body wall of insects, including the entire wing, is derived from these two ancestral proximal leg segments. This model explains all observations in favor of either the body wall origin or proximal leg origin of insect wings. Thus, our results show that insect wings are not novel structures, but instead evolved from existing, ancestral structures.One Sentence SummaryCRISPR-Cas9 knockout of leg gap genes in a crustacean reveals that insect wings are not novel structures, they evolved from crustacean leg segments

scholarly journals A Unified Framework to Homologize Appendage Segments across Arthropoda

2020 ◽  
Author(s):  
Heather Bruce ◽  
Nipam Patel
Keyword(s):  
Convergent Evolution ◽  
Body Wall ◽  
The Body ◽  
Loss Of Function ◽  
Unified Framework ◽  
Powerful System ◽  
Patterning Genes ◽  
One To One ◽  
Novel Structures

How to align leg segments between the four groups of arthropods (insects, crustaceans, myriapods, and chelicerates) has tantalized researchers for over a century. By comparing the loss-of-function phenotypes of leg patterning genes in diverged arthropod taxa, including a crustacean, insects, and spiders, we show that all arthropod legs can be aligned in a one-to-one fashion. We propose a model wherein insects incorporated two proximal leg segments into the body wall, which moved the ancestral leg lobe (exite) up onto the back to later form wings. For myriapods and chelicerates with seven leg segments, it appears that one proximal leg segment was incorporated into the body wall. According to this model, the chelicerate exopod and the crustacean exopod emerge from different leg segments, and are therefore proposed to have arisen independently. A framework for how to align arthropod appendages now opens up a powerful system for studying the origins of novel structures, the plasticity of developmental fields, and convergent evolution.

scholarly journals How to align arthropod leg segments

2021 ◽  
Author(s):  
Heather S. Bruce
Keyword(s):  
Convergent Evolution ◽  
Body Wall ◽  
The Body ◽  
Loss Of Function ◽  
Powerful System ◽  
Patterning Genes ◽  
One To One ◽  
Novel Structures

AbstractHow to align leg segments between the four groups of arthropods (insects, crustaceans, myriapods, and chelicerates) has tantalized researchers for over a century. By comparing the loss-of-function phenotypes of leg patterning genes in diverged arthropod taxa, including a crustacean, insects, and arachnids, arthropod legs can be aligned in a one-to-one fashion. By comparing the expression of pannier and aurucan, the proximal leg segments can be aligned. A model is proposed wherein insects and myriapods incorporated the proximal leg region into the body wall, which moved an ancestral exite (for example, a gill) on the proximal leg into the body wall, where it invaginated independently in each lineage to form tracheae. For chelicerates with seven leg segments, it appears that one proximal leg segment was incorporated into the body wall. According to this model, the chelicerate exopod and the crustacean exopod emerge from different leg segments, and are therefore proposed to have arisen independently. A framework for how to align arthropod appendages now opens up a powerful system for studying the origins of novel structures, the plasticity of developmental fields across vast phylogenetic distances, and the convergent evolution of shared ancestral developmental fields.

scholarly journals Two sets of wing homologs in the crustacean, Parhyale hawaiensis

2017 ◽  
Author(s):  
Courtney M. Clark-Hachtel ◽  
Yoshinori Tomoyasu
Keyword(s):  
Genome Editing ◽  
Regulatory Network ◽  
Body Wall ◽  
Ancestral State ◽  
Insect Wing ◽  
Insect Wings ◽  
Parhyale Hawaiensis ◽  
Gene Regulatory ◽  
Competing Hypotheses ◽  
Dual Origin

The origin of insect wings is a biological mystery that has fascinated scientists for centuries. Through extensive investigations performed across various fields, two possible wing origin tissues have been identified; a lateral outgrowth of the dorsal body wall (tergum) and ancestral proximal leg structures1,2. With each idea offering both strengths and weaknesses, these two schools of thought have been in an intellectual battle for decades without reaching a consensus3. Identification of tissues homologous to insect wings from linages outside of Insecta will provide pivotal information to resolve this conundrum. Here, through expression analyses and CRISPR/Cas9-based genome-editing in the crustacean, Parhyale hawaiensis, we show that a wing-like gene regulatory network (GRN) operates both in the crustacean terga and in the proximal leg segments, suggesting that (i) the evolution of a wing-like GRN precedes the emergence of insect wings, and (ii) that both of these tissues are equally likely to be crustacean wing homologs. Interestingly, the presence of two sets of wing homologs parallels previous findings in some wingless segments of insects, where wing serial homologs are maintained as two separate tissues4–7. This similarity provides crucial support for the idea that the wingless segments of insects indeed reflect an ancestral state for the tissues that gave rise to the insect wing, while the true insect wing represents a derived state that depends upon the contribution of two distinct tissues. These outcomes point toward a dual origin of insect wings, and thus provide a crucial opportunity to unify the two historically competing hypotheses on the origin of this evolutionarily monumental structure.

scholarly journals The Daphnia Carapace and the Origin of Novel Structures

2021 ◽  
Author(s):  
Heather Bruce
Keyword(s):  
General Solution ◽  
Body Wall ◽  
Lateral Lobe ◽  
Central Question ◽  
Insect Wing ◽  
Insect Wings ◽  
Positive Region ◽  
Novel Structure ◽  
Novel Structures

Understanding how novel structures arise is a central question in evolution. The carapace of the waterflea Daphnia is a bivalved “cape” of exoskeleton that surrounds the animal, and has been proposed to be one of many novel structures that arose through repeated co-option of genes that also pattern insect wings. To determine whether the Daphnia carapace is a novel structure, the expression of pannier, the Iroquois gene aurucan, and vestigial are compared between Daphnia, Parhyale, and Tribolium. The results suggest that the Daphnia carapace did not arise by cooption, but instead represents an elongated ancestral exite (lateral lobe or plate) that emerges from a proximal leg segment that was incorporated into the Daphnia body wall. The Daphnia carapace therefore appears to be homologous to the Parhyale tergal plate and the insect wing. In addition, the vg-positive region that gives rise to the Daphnia carapace also appears to be present in Parhyale and Tribolium, which do not form a carapace. Thus, rather than a novel structure resulting from gene co-option, the carapace appears to have arisen from an ancient, conserved developmental field that persists in a cryptic state in other arthropod lineages, but in Daphnia became elaborated into the carapace. Cryptic persistence of serially homologous developmental fields may thus be a general solution for the origin of many novel structures.

scholarly journals The Daphnia Carapace and the Origin of Novel Structures

2021 ◽  
Author(s):  
Heather Bruce
Keyword(s):  
General Solution ◽  
Body Wall ◽  
Lateral Lobe ◽  
Central Question ◽  
Insect Wing ◽  
Insect Wings ◽  
Positive Region ◽  
Novel Structure ◽  
Novel Structures

Understanding how novel structures arise is a central question in evolution. The carapace of the waterflea Daphnia is a bivalved “cape” of exoskeleton that surrounds the animal, and has been proposed to be one of many novel structures that arose through repeated co-option of genes that also pattern insect wings. To determine whether the Daphnia carapace is a novel structure, the expression of pannier, the Iroquois gene aurucan, and vestigial are compared between Daphnia, Parhyale, and Tribolium. The results suggest that the Daphnia carapace did not arise by cooption, but instead represents an elongated ancestral exite (lateral lobe or plate) that emerges from a proximal leg segment that was incorporated into the Daphnia body wall. The Daphnia carapace therefore appears to be homologous to the Parhyale tergal plate and the insect wing. In addition, the vg-positive region that gives rise to the Daphnia carapace also appears to be present in Parhyale and Tribolium, which do not form a carapace. Thus, rather than a novel structure resulting from gene co-option, the carapace appears to have arisen from an ancient, conserved developmental field that persists in a cryptic state in other arthropod lineages, but in Daphnia became elaborated into the carapace. Cryptic persistence of serially homologous developmental fields may thus be a general solution for the origin of many novel structures.

scholarly journals The Daphnia carapace and the origin of novel structures

2021 ◽  
Author(s):  
Heather S. Bruce ◽  
Nipam H. Patel
Keyword(s):  
General Solution ◽  
Body Wall ◽  
Lateral Lobe ◽  
Central Question ◽  
Insect Wing ◽  
Functional Studies ◽  
Insect Wings ◽  
Positive Region ◽  
Novel Structure ◽  
Novel Structures

SummaryUnderstanding how novel structures arise is a central question in evolution. The carapace of the waterflea Daphnia is a bivalved “cape” of exoskeleton that has been proposed to be one of many novel arthropod structures that arose through repeated co-option of genes that also pattern insect wings1–3. To determine whether the Daphnia carapace is a novel structure, we compare the expression of pannier, araucan, and vestigial between Daphnia, Parhyale, and Tribolium. Our results suggest that the Daphnia carapace did not arise by co-option, but instead derives from an ancestral exite (lateral lobe) that emerges from a proximal leg segment that was incorporated into the Daphnia body wall. The Daphnia carapace therefore appears to be homologous to the Parhyale tergal plate and the insect wing4. Remarkably, the vestigial-positive region that gives rise to the Daphnia carapace appears to be present in Parhyale5 and Tribolium as a small, inconspicuous protrusion. Similarly, the vestigial-positive developmental fields that form tergal plates in Parhyale appear to be present in Daphnia, even though Daphnia does not form tergal plates. Thus, rather than a novel structure resulting from gene co-option, the Daphnia carapace appears to have arisen from a shared, ancestral developmental field that persists in a cryptic state in other arthropod lineages. Cryptic persistence of unrecognized serially homologous developmental fields may thus be a general solution for the origin of novel structures. Our simple molecular triangulation strategy, which does not require functional studies, can illuminate the homologies of long-debated structures on the legs and body wall of arthropods.

Locomotion and Coelomic Pressure in Lumbricus Terrestris L

1969 ◽  
Vol 51 (1) ◽  
pp. 47-58
Author(s):  
M. K. SEYMOUR
Keyword(s):  
Internal Pressure ◽  
Body Wall ◽  
Circular Muscle ◽  
Lumbricus Terrestris ◽  
The Body ◽  
Initial Penetration ◽  
Cine Film ◽  
Body Wall Muscles ◽  
Longitudinal Muscles ◽  
Do So

1. Crawling movement and burrowing of Lumbricus terrestris (L.) have been studied by continuous recording of internal pressure, direct observation and analysis of cine film. Frequency of locomotory waves is from 5 to 20 per min. Timing of protrusion of setae and of backward slip of points d'appui in locomotion have been observed and recorded. 2. In normal locomotion elongation of segments by contraction of the circular muscles gives rise to a discrete pressure pulse; shortening, by contraction of the longitudinal muscles, may or may not do so, depending on the position of the segment in the worm and the relative extent of contraction of the longitudinal and circular muscles. 3. Consideration of crawling and burrowing pressure records emphasizes the importance of (a) the circular muscles in extension of the head end in crawling and in initial penetration of the soil, and (b) the longitudinal muscles during burrowing, in dilating the burrow and drawing in more posterior segments 4. Mean pressures at circular and longitudinal muscle contraction are 12 and 7 cm. H2O respectively. The highest pressure recorded was 75 cm. H2O and accompanied violent squirming with evident contraction of all the body wall muscles. Resting pressures, shown in the absence of organized movement, are low (mean 0.26 cm. H2O). In both resting and crawling negative pressures sometimes occur and these are considered in relation to the inherent stiffness of the body wall and to the septate condition. 5. Tension in the longitudinal and circular muscle layers of a worm developing 75 cm. H2O internal pressure are calculated to be 265 and 1323 g./cm2. respectively, demonstrating in this example that, relative to the circulars, the longitudinal muscles are understressed by a factor of 5. Mean locomotory L.M. and C.M. peak values yield tension values of only 25 and 212 g./cm. respectively, and these are clearly well within the worm's capacity.

scholarly journals A wing growth organizer in a hemimetabolous insect suggests wing origin

2021 ◽  
Author(s):  
Takahiro Ohde ◽  
Taro Mito ◽  
Teruyuki Niimi
Keyword(s):  
Body Wall ◽  
The Body ◽  
Marker Genes ◽  
Wing Development ◽  
Gryllus Bimaculatus ◽  
Genetic Changes ◽  
Origin And Evolution ◽  
Insect Wings ◽  
Hemimetabolous Insect ◽  
Wing Growth

ABSTRACTThe origin and evolution of insect wings remain enigmatic after a century-long discussion. Molecular dissection of wing development in hemimetabolous insects, in which the first functional wings evolved, is key to understand genetic changes required for wing evolution. We investigatedDrosophilawing marker genes in the cricket,Gryllus bimaculatus, and foundapterousandvestigialshow critical functions in nymphal tergal identity and margin formation, respectively. We further demonstrate that margin cells in the lateral-anterior tergal region constitute a growth organizer of wing blades. Transcriptome and RNAi analyses unveiled that Wnt, Fat-Dachsous, and Hippo pathways are involved in disproportional growth ofGrylluswings. Our data collectively support the idea that tergal margin cells of a wingless ancestor gave rise to the body wall extension required for evolution of the first powered flight.

SPECT-Befunde bei Hemiparkinson-Syndrom mit 99mTc-HMPAO

1989 ◽  
Vol 28 (03) ◽  
pp. 92-94 ◽  
Author(s):  
C. Neumann ◽  
H. Baas ◽  
R. Hefner ◽  
G. Hör
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Basal Ganglia ◽  
Neuronal Activity ◽  
Tracer Uptake ◽  
The Body ◽  
99Mtc Hmpao ◽  
Do So

The symptoms of Parkinson’s disease often begin on one side of the body and continue to do so as the disease progresses. First SPECT results in 4 patients with hemiparkinsonism using 99mTc-HMPAO as perfusion marker are reported. Three patients exhibited reduced tracer uptake in the contralateral basal ganglia One patient who was under therapy for 1 year, showed a different perfusion pattern with reduced uptake in both basal ganglia. These results might indicate reduced perfusion secondary to reduced striatal neuronal activity.

Lymphangiomatosis of the Body Wall: A Report of Two Cases Associated with Chylothorax and Fatal Outcome

1997 ◽  
Vol 17 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Philippe Moerman ◽  
Chris Van Geet ◽  
Hugo Devlieger
Keyword(s):  
Body Wall ◽  
Fatal Outcome ◽  
The Body
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