Zebrafish eda and edar Mutants Reveal Conserved and Ancestral Roles of Ectodysplasin Signaling in Vertebrates

The more subtle phenotypes observed in the medaka mutant are likely due to partial loss of function of edar caused by a hypomorphic rs-3 allele.

“As the phenotype of the rs-3 mutant is similar to the fls dfang allele in the zebrafish, it is likely that the more subtle phenotypes observed in the medaka mutant is due to partial loss of function of edar caused by a hypomorphic rs-3 allele [47].”

• cites [47] S Kondo, 2001, The medaka rs-3 locus required for scale development encodes ectodysplasin -A receptor., Curr Bio sourceDisputed

  The Results and discussion identify rs-3 as an EDAR mutation and report no detectable defects beyond scale loss. But the paper says the mutant transcript likely prevents EDAR protein synthesis, contrary to the claim that the allele retains partial function; it does not make the zebrafish comparison. (LLM, conf=0.86)

  Checked by a reasoning model — may be wrong.

  Experimental — accuracy not yet measured

These mutations were found at identical positions as seen in familial cases of HED in humans.

“These mutations were found at identical positions as seen in familial cases of HED in humans (Figure 3B, E; [11],[12].”

• cites [11] AW Monreal, 1999, Mutations in the human homologue of mouse dl cause autosomal recessive and dominant hypohidrotic ectodermal dysplasia., Nat Genet sourceNot checked — no full text of the source
• cites [12] LK Lind, 2006, EDAR mutation in autosomal dominant hypohidrotic ectodermal dysplasia in two Swedish families., BMC Med Genet sourcePartly supported

  The Discussion reports that the EDAR p.Arg358X mutation in two Swedish families is identical to one previously described in an American family with HED. It does not establish that the unspecified multiple mutations referred to as “these mutations” occur at identical positions in human familial cases. (LLM, conf=0.78)

  Experimental — accuracy not yet measured

Eda signaling is necessary for the development and patterning of epithelial placodes of many integumentary organs in both mouse and chick.

“Eda signaling is necessary for the development and patterning of epithelial placodes of many integumentary organs in both the mouse and chick [19]–[22].”

• cites [19] G Barsh, 1999, Of ancient tales and hairless tails., Nat Genet sourceNot checked — no full text of the source
• cites [20] C Mou, 2006, Generation of the primary hair follicle pattern., Proc Natl Acad Sci U S A sourcePartly supported

  The introduction (p. 1) says the Eda–Edar–Edaradd pathway is required for a specific subset of mouse hair follicles, and the Discussion (p. 5) says loss of Edar signaling blocks primary follicle formation. The paper does not establish necessity for placodes of many organs in both mouse and chick: its discussion of scales, feathers, and teeth is explicitly speculative. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [21] L Houghton, 2005, The ectodysplasin pathway in feather tract development., Development sourceNot checked — no full text of the source
• cites [22] CF Drew, 2007, The Edar subfamily in feather placode formation., Dev Biol sourcePartly supported

  The Introduction says the Eda pathway is required to initiate primary hair follicles in mice, and the Discussion reports that suppressing related signaling in chick skin impairs feather placode formation and changes bud density. But the Discussion also says receptor activity is not required for the initial assumption of placodal fate. The paper does not establish necessity for the placodes of many organ types in both species; these passages have no page number in our copy. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

The I418T mutation in human, which affects the same amino acid as fls dt3Tpl (I327F), shows distinct phenotypic variability depending on genetic background.

“For example, the I418T mutation in human, which affects the same amino acid as fls dt3Tpl (I327F), shows distinct phenotypic variability depending on genetic background [18].”

• cites [18] N Chassaing, 2006, Mutations in EDAR account for one-quarter of non-ED1-related hypohidrotic ectodermal dysplasia., Hum Mutat sourcePartly supported

  The Results report p.Ile418Thr in an affected girl whose father carried the variant but had only minor abnormalities. They describe intrafamilial phenotypic variability as a possibility, not an established effect, and say the variant’s role needs confirmation. The paper does not attribute the difference to genetic background or identify the mouse I327F mutation as affecting the corresponding amino acid. Page numbers are unavailable in our copy. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Autosomal dominant HED in humans caused by mutation of EDAR within the death domain displays a large degree of phenotypic variability.

“Autosomal dominant HED in humans caused by mutation of EDAR within the death domain displays a large degree of phenotypic variability [12].”

• cites [12] LK Lind, 2006, EDAR mutation in autosomal dominant hypohidrotic ectodermal dysplasia in two Swedish families., BMC Med Genet sourcePartly supported

  The Discussion reports variable symptoms, including differences among people carrying the same EDAR mutation. It also specifies that the p.Arg358X mutation truncates EDAR at amino acid 358, abolishing the death domain at amino acids 367–431. Thus the variability is supported, but the mutation is not located within the death domain as claimed. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

Both the expression of Edar and related receptor, Troy, have been detected in the AER of mice.

“both the expression of Edar and related receptor, Troy, have been detected in the AER of mice [40],[41].”

• cites [40] J Pispa, 2003, Ectodysplasin, Edar and TNFRSF19 are expressed in complementary and overlapping patterns during mouse embryogenesis., Gene Expr Patterns sourceNot checked — no full text of the source
• cites [41] AS Tucker, 2000, Edar/Eda interactions regulate enamel knot formation in tooth morphogenesis., Development sourcePartly supported

  The section “Expression of Dl and Ta in tooth development” reports strong expression of Dl (Edar) in the apical ectodermal ridge of a mouse limb at E10; the Fig. 1 caption also identifies AER expression. Our copy does not report Troy expression in the AER, so it supports only the Edar part of the claim. (LLM, conf=0.90)

  Experimental — accuracy not yet measured

There are several reports of hypodontia in humans resulting from altered EDA function that do not show other phenotypes such as hypothrichosis or nail defects.

“There are several reports of hypodontia in humans resulting from altered EDA function that do not show other phenotypes such as hypothrichosis or nail defects [50]–[52].”

• cites [50] S Li, 2008, Non-syndromic tooth agenesis in two Chinese families associated with novel missense mutations in the TNF domain of EDA (ectodysplasin A)., PLoS ONE sourceSupported
• cites [51] R Tao, 2006, A novel missense mutation of the EDA gene in a Mongolian family with congenital hypodontia., J Hum Genet sourceNot checked — no full text of the source
• cites [52] P Tarpey, 2007, A novel Gln358Glu mutation in ectodysplasin A associated with X-linked dominant incisor hypodontia., Am J Med Genet A sourceNot checked — no full text of the source

A QTL of lateral plate formation in a low-plated form of the stickleback indicates a significant modification of the reduced plate phenotype (eda locus) with modifying effects within and between loci affecting plate number and size.

“A quantitative trait analysis (QTL) of lateral plate formation in a low-plated form of the stickleback indicates a significant modification of the reduced plate phenotype (eda locus) with modifying effects within and between loci affecting plate number and size [53],[54].”

• cites [53] CL Piechel, 2001, The genetic architecture of divergence between threespine stickleback species., Nature sourceNot checked — no full text of the source
• cites [54] PF Colosimo, 2004, The genetic architecture of parallel armor plate reduction in threespine sticklebacks., PLoS Biol sourcePartly supported

  The Results and Discussion (QTL Architecture; page unavailable) identify a major LG 4 locus affecting plate morph, additional unlinked QTL modifying plate number, and QTL affecting plate size. They do not identify the major locus as Eda or establish modifying effects within that locus; the paper says further molecular work is needed to determine whether the LG 4 region contains one or multiple mutations. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

Similar dose sensitive responses to levels of EDA signaling are seen in tooth development of the mouse regulating the number and shape of teeth.

“Similar dose sensitive responses to levels of EDA signaling are seen in tooth development of the mouse regulating the number and shape of teeth [48],[49].”

• cites [48] AS Tucker, 2004, The activation level of the TNF family receptor, Edar, determines cusp number and tooth number during tooth development., Dev Biol sourceSupported
• cites [49] AT Kangas, 2004, Nonindependence of mammalian dental characters., Nature sourceNot checked — no full text of the source

With the exception of the fls tfng allele, the lepidotrichia that form during juvenile metamorphosis are defective, leading to fin loss in the adult.

“With the exception of the fls tfng allele, the lepidotrichia that form during juvenile metamorphosis are defective, leading to fin loss in the adult (Figure 1D, 2A).”

Scales are largely absent with infrequent formation of inappropriately shaped scales near the dorsal, anal and pectoral fins.

“scales are largely absent with infrequent formation of inappropriately shaped scales near the dorsal, anal and pectoral fins (Figure 1D, 2A).”

fls dt3Tpl fish exhibit the strong fls phenotype when homozygous or heterozygous with other fls alleles.

“Mutant fls dt3Tpl fish exhibit the strong fls phenotype when homozygous or heterozygous with other fls alleles.”

Three mutants showed nearly identical defects in formation of scales, lepidotrichia, and shape of the skull of homozygous fish.

“we identified three mutants that showed nearly identical defects in the formation of scales, lepidotrichia, and shape of the skull of homozygous fish.”

Similar to Nkt, fls dt3Tpl exhibits a dominant effect on skull shape.

“Similar to Nkt, fls dt3Tpl exhibits a dominant effect on skull shape as well (Figure S1).”

The fls te370f mutation was linked to SSLP markers on linkage group 9 (LG9).

“The fls te370f mutation was linked to SSLP markers on linkage group 9 (LG9).”

The expressivity of dominant alleles is sensitive to background modifiers that buffer the phenotypic consequences of loss of Eda signaling.

“the expressivity of dominant alleles is sensitive to background modifiers that buffer the phenotypic consequences of loss of Eda signaling.”

The eda transcript from the Nkt mutant shows a precocious stop codon predicting a truncation of the protein at the beginning of the TNF domain (S243X).

“The eda transcript from the Nkt mutant shows a precocious stop codon predicting a truncation of the protein at the beginning of the TNF domain, which is involved in ligand-receptor binding (S243X(C-A)); Figure 3G and Figure S3).”

The expressivity of the dominant fls dt3Tpl phenotype depends on the genetic background.

“The expressivity of the dominant fls dt3Tpl phenotype depends on the genetic background.”

The shape and number of scales in fang is similar to the other homozygous fls alleles.

“The shape and number of the scales in fang is similar to the other homozygous fls alleles (Table 1).”

Fish heterozygous for fls dt3Tpl exhibited either a strong or a weak phenotype in the Tü background.

“Fish heterozygous for fls dt3Tpl exhibited either a “strong” or a “weak” phenotype in the Tü background (Figure 1G and J, respectively).”

The novel isoform has an addition of intronic sequence leading to a premature termination codon.

“Analysis of the sequence of the novel isoform showed the addition of intronic sequence leading to a premature termination codon (Figure 3C).”

Nkt homozygous fish exhibit more severe defects in formation of the dermal skeleton than fls alleles in extent of lepidotrichial growth and number of residual scales formed.

“Nkt homozygous fish exhibit more severe defects in the formation of the dermal skeleton than fls alleles in the extent of lepidotrichial growth and number of residual scales formed (compare Figure 1D and Figure 2A).”

The altered splicing is due to an A to G transition leading to the creation of a new splice donor site in the intron.

“Analysis of the genomic sequence in the mutant revealed that the altered splicing is due to an A to G transition leading to the creation of a new splice donor site in the intron (Figure 3C).”

None of the other fls alleles showed any dominance in the Tü, TLF, or WIK strains.

“None of the other fls alleles showed any dominance in the Tü, TLF, or WIK strains.”

flstfng heterozygotes do not show any differences compared with wild type.

“flstfng heterozygotes do not show any differences compared to wild type.”

fls is allelic to the previously isolated finless mutant.

“The first is allelic to the finless (fls te370f ) mutant that was previously isolated in the background of the Tübingen wild type stock (Tü) on the basis of the loss of fins in adults [10].”

• cites [10] P Haffter, 1996, Mutations affecting pigmentation and shape of the adult zebrafish., Dev Genes Evol sourceNot checked — no full text of the source

The edar gene is located on LG9 within the determined linkage interval for fls.

“The edar gene is located on LG9 within the determined linkage interval for fls (see Methods).”

The two ENU-generated alleles have missense mutations resulting in amino acid changes in the death domain (fls t3R367W, R367W; fls dt3Tpl, I428F).

“The two alleles generated by the ENU mutagen both have missense mutations resulting in amino acid changes in the death domain (fls t3R367W, R367W(C-T); fls dt3Tpl, I428F (A-T)).”

These mutants fell into two complementation groups.

“These mutants fell into two complementation groups.”

The fang allele (fls tfng) homozygotes have only one tooth on the fifth ceratobranchial.

“We named this allele fang (fls tfng) after its unique dental phenotype in homozygotes of having only one tooth on the fifth ceratobranchial (Figure 1N).”

Analysis of edar RNA from homozygous fls tfng showed the presence of two distinct transcripts with an additional larger isoform than seen in wildtype.

“Analysis of edar RNA from homozygous fls tfng showed the presence of two distinct transcripts with an additional larger isoform than seen in wildtype.”

The Nkt homozygous phenotype is more severe than that of strong fls alleles.

“The homozygous phenotype is more severe than that of strong fls alleles (Figure 2A).”

The fang-specific edar transcript represents 74% of the total pool of edar transcripts in homozygous mutants.

“Using quantitative real time PCR we found that the fang-specific edar transcript represents 74% of the total pool of edar transcripts in homozygous mutants (Figure 3D).”

The dermal bones of the pectoral girdle are present and patterned appropriately in both fls and Nkt mutants.

“The dermal bones of the pectoral girdle are present and patterned appropriately in both the fls and Nkt mutants.”

eda is located on LG5.

“An analysis of the location of eda in the zebrafish radiation hybrid map placed eda on LG5.”

In early fin fold stage of pectoral fin development (8 mm), edar expression was detected in both the distal margin of the endochondrial radials and more distally in the forming lepidotrichial rays.

“In early fin fold stage of pectoral fin development (8 mm), we detected edar expression in both the distal margin of the endochondrial radials (black arrowhead, Figure 7A) as well as more distally in the forming lepidotrichial rays (Figure 7A).”

In fls mutant, residual expression of edar, shh, and bmp2b was found in the posterior margin of the pectoral fin.

“However, residual expression of all three genes was found in the posterior margin of the fin (Figure 7B, D, J arrow).”

In fls adults, fusions of the distal radials of the pectoral fin are seen at low penetrance.

“In fls adults, fusions of the distal radials of the pectoral fin are seen at a low penetrance (Figure 6G, data not shown).”

The pelvic fin showed similar expression of edar in forming lepidotrichial rays.

“The pelvic fin showed similar expression of edar in forming lepidotrichial rays (Figure 7E).”

During late fin development, edar expression was observed in forming lepidotrichia of all fins with a distal bias.

“The expression of edar during late fin development was observed in forming lepidotrichia of all fins with a distal bias in its expression (Figure 8C).”

Developmental genes shh and bmp2b show similar placodal expression as edar.

“Developmental genes shh and bone morphogenic protein 2b (bmp2b), whose orthologues are known to be essential for placode development in the mouse and chick, show similar placodal expression as seen with edar (Figure 4E and G).”

msxa, a marker of the distal epithelium, is differentially expressed in the fls mutant.

“Consistent with these data suggesting asymmetrical loss of the fin fold epidermis, we find that msxa, a marker of the distal epithelium, is differentially expressed in the mutant (Figure 7Q and R).”

• AssumptionRests on an assumption: msxa is a marker of the distal epithelium.

shh and bmp2b expression was observed in the forming lepidotrichia of both the pectoral and pelvic fins of wild type juveniles, having a similar distal bias in the leading margin of all rays.

“shh and bmp2b expression was observed in the forming lepidotrichia of both the pectoral and pelvic fins of wild type juveniles, having a similar distal bias in the leading margin of all rays (Figure 7C, G and I, K, respectively).”

Histological analysis of fls mutant fins at an early stage of lepidotrichial formation revealed a general deficiency of development of the entire mesodermal component of the fin such as cartilage and muscle in both paired and unpaired fins.

“Histological analysis of fls mutant fins at an early stage of lepidotrichial formation reveal a general deficiency of the development of the entire mesodermal component of the fin such as cartilage and muscle in both the paired (pectoral fin, Figure 8D, E) and unpaired fins (anal and caudal fins, Figure 8F–G; H–I, respectively).”

Close inspection of the distal tip of fls mutant fins showed disorganization of the epidermis and degeneration of distal epidermal nuclei.

“However, close inspection of the distal tip of the fins showed disorganization of the epidermis and degeneration of distal epidermal nuclei (insets Figure 8F, J).”

In pelvic fin of 8-9 mm juvenile fls mutants, retention of acridine orange label was seen in the anterior distal margin.

“Similarly, in the pelvic fin of 8–9 mm juveniles, retention of the label was seen in the anterior distal margin of the fin (Figure 7O–P).”

Adjacent lateral epidermal cells show high levels of both ER and hemidesmosomes.

“In contrast, the adjacent lateral epidermal cells show high levels of both ER and hemidesmosomes (data not shown and Figure 5G brackets, respectively).”

Expression of edar is seen in the basal cells of forming scale placodes arising during early specification of the scale placode.

“The expression of edar is seen in the basal cells of forming scale placodes (Figure 5J–L; stages 1–3 Figure 5M) arising during early specification of the scale placode (s1; arrowhead Figure 5K).”

In Nkt, there is an increase in the frequency of patterning and growth defects of the endochondrial components of the fin.

“In Nkt, there is an increase in the frequency of patterning and growth defects of the endochondrial components of the fin (Figure 6G).”

Nkt causes a strong effect on lepidotrichial growth of both the pectoral and pelvic fins.

“Nkt causes a strong effect on lepidotrichial growth of both the pectoral and pelvic fins (Figure 6E–F, J).”

A specific alteration in the morphology of basal epidermal cells in wild type juvenile fish coincides with the initial accumulation of fibroblasts at the sites of scale development.

“We find a specific alteration in the morphology of the basal epidermal cells in wild type juvenile fish that coincides with the initial accumulation of fibroblasts at the sites of scale development (Figure 5B, E).”

In fls mutant, expression of edar, shh, and bmp2b was decreased in the anterior portion of the pectoral fins.

“Expression of all three genes in fls was decreased in the anterior portion of the pectoral fins (Figure. 7B, D, J).”

No difference in bmp2b expression was detected in the pelvic fins of fls mutant despite obvious morphological differences in developing rays.

“We did not detect any difference in bmp2b expression in the pelvic fins even though obvious morphological differences in the developing rays of the samples could be seen (Figure 7L).”

The expression of edar is associated with that of shh and bmp2b.

“The expression of edar is again associated with that of shh and bmp2b.”

In 7 mm juvenile fls mutants and siblings, differential retention of acridine orange was detected in the anterior and anterior-distal margin of the developing pectoral fin.

“In 7 mm juveniles, we detect a differential retention of acridine orange between fls and siblings in the anterior, and anterior-distal margin of the developing pectoral fin (Figure 7M–N).”

The expression of edar in the forming dermal ray was similar in both location and timing to that of bmp2b and shh.

“The expression in the forming dermal ray was similar in both location and timing to that of bmp2b and shh (Figure 8A–B, asterisk).”

In fls te370f juvenile fish, at a corresponding site on the flank as in wild type, there is formation of similar aggregations of basal epidermal cells.

“In fls te370f juvenile fish, at a corresponding site on the flank as in wild type, we detected the formation of similar aggregations of basal epidermal cells (black arrows. Figure 5C, F).”

A clear signal for eda in the forming fins could not be resolved using WMISH.

“We were unable to resolve a clear signal for eda in the forming fins using WMISH.”

In fls, there is a specific effect on the growth of anterior lepidotrichia of the pelvic fin where the dermal rays of the anterior (e.g. 1,2) are significantly shorter than rays at equivalent positions in wild type.

“In contrast, a specific effect on the growth of anterior lepidotrichia of the pelvic fin is seen in fls where the dermal rays of the anterior (e.g. 1,2) are significantly shorter than rays at equivalent positions in wild type (Figure 6I).”

edar expression in the fin fold had a posterior bias in wild type fins.

“The expression of edar in the fin fold had a posterior bias in wild type fins (Figure 7A, white arrow).”

Expression of both edar and eda presaged the formation of the initial scale row along the flank just ventral from the midline myoseptum in the caudal peduncle.

“The expression of both genes presaged the formation of the initial scale row along the flank just ventral from the midline mysoseptum in the caudal peduncle (arrowheads, Figure 4A and C; [24]).”

• cites [24] JY Sire, 1997, Scale development in zebrafish (Danio rerio)., J Anat sourceNot checked — no full text of the source

The growth and patterning of lepidotrichia are affected in all fins.

“The growth and patterning of lepidotrichia are affected in all fins.”

Unpaired fins showed no defects in patterning of the endochondrial bones of the proximal and distal radials.

“Unpaired fins showed no defects in patterning of the endochondrial bones of the proximal and distal radials (Figure 6K–P);”

This is observed above the localized accumulation of fibroblasts in the dermis.

“This is observed above the localized accumulation of fibroblasts in the dermis (white arrows, Figure 5B, E).”

In wild type juvenile fish, there is formation of histologically defined, localized assemblies of cells of the basal epidermis that resemble early stages of the formation of hair and feather placodes.

“To our surprise, in wild type juvenile fish, we discovered the formation of histologically defined, localized assemblies of cells of the basal epidermis that resemble early stages of the formation of hair and feather placodes.”

In pelvic fins of fls mutant, loss of anterior expression of edar and shh was seen.

“In the pelvic fins, similar loss of anterior expression of edar (Figure 7F) and shh (Figure 7H) was seen in the fls mutant.”

The fls dt3Tpl zebrafish mutant displays similar dominance and variation as the human allele affecting the same residue.

“Interestingly, the fls dt3Tpl zebrafish mutant displays similar dominance and variation as the human allele affecting the same residue.”

edar was expressed proximally between forming rays and at the distal margin.

“In addition, edar was found expressed proximally between forming rays and at the distal margin (Figure 8C arrow).”

The fang allele of fls demonstrates dose sensitivity as functional copies of Edar are titrated by the concomitant use of a new splice site in the mutant leading to the reduction in the amount of wild type transcript made.

“Similarly, the fang allele of fls clearly demonstrates this dose sensitivity as functional copies of Edar are titrated by the concomitant use of a new splice site in the mutant leading to the reduction in the amount of wild type transcript made (Figure 3D).”

Radiation hybrid screening indicated linkage of zebrafish edar to markers positioned on LG9 in the region predicted by initial mapping analysis.

“Results from radiation hybrid screening indicated linkage of zebrafish edar to markers positioned on LG9 in the region predicted by initial mapping analysis.”

Rough mapping of F2 progeny against a reference panel of SSLP markers indicated that fls was located on linkage group (chromosome) 9 (LG9) with loose linkage to z20031 (61.3cR).

“Rough mapping of F2 progeny against a reference panel of SSLP markers [63] indicated that fls was located on linkage group (chromosome) 9 (LG9) with loose linkage to z20031 (61.3cR; Figure 3A).”

• cites [63] R Geisler, 2002, Mapping and Cloning. sourceNot checked — no full text of the source

In analysis of the medaka rs-3/edar mutant, a high degree of variability in the extent of scale formation was found, suggesting the existence of background modifiers of Edar function in this species.

“In our analysis of the medaka rs-3/edar mutant, we find a high degree of variability in the extent of scale formation (Figure S4) suggesting the existence of background modifiers of Edar function in this species.”

fls was closely linked to markers z7001 and z11672.

“We found fls to be closely linked to markers z7001 and z11672.”

Significant modification of expressivity of fls dt3Tpl was observed in different genetic backgrounds, indicating the existence of genetic modifiers of Eda signaling.

“Supporting this finding, we observed significant modification of expressivity of fls dt3Tpl in different genetic backgrounds indicating the existence of genetic modifiers of Eda signaling.”

Analysis of flanking markers and internal polymorphisms in edar showed tight linkage of the fls mutation to the edar gene.

“Analysis of flanking markers and internal polymorphisms in edar showed tight linkage of the fls mutation to the edar gene.”

The predicted protein would be similar to the fls t0sp212 allele, having a truncation just after the transmembrane domain at amino acid 218.

“The predicted protein would be similar to the fls t0sp212 allele having truncation just after the transmembrane domain at amino acid 218 (Figure 3B and Figure S2).”

There is substantial buffering of the effect of loss of edar function in different genetic backgrounds, suggesting canalization of this developmental system.

“we show substantial buffering of the effect of loss of edar function in different genetic backgrounds, suggesting canalization of this developmental system.”

Genetic analysis demonstrates a dose-sensitive and organ-specific response to alteration in levels of Eda signaling.

“Our genetic analysis demonstrates dose-sensitive and organ-specific response to alteration in levels of Eda signaling.”

Developmental mechanisms involved in the formation and variation of both integumentary appendages and limbs are conserved.

“show conservation of the developmental mechanisms involved in the formation and variation of both integumentary appendages and limbs.”

Given the presence of both isoforms, the novel splice site is used in addition to the normal splice junction.

“Given the presence of both isoforms in homozygous individuals, this novel splice site is used in addition to the normal splice junction.”

The dilution of wild type transcripts can explain the observed hypomorphic effect of the fang allele.

“The dilution of wild type transcripts can explain the observed hypomorphic effect of the allele.”

Eda signaling is required in the zebrafish epidermis for formation of a structure resembling an epidermal placode seen in early development of other vertebrate integumentary appendages.

“We describe the requirement of Eda signaling in the zebrafish epidermis for the formation of a structure resembling an epidermal placode seen in the early development of other vertebrate integumentary appendages.”

Dominant modifier loci are present in the WIK strain that buffer the expressivity of the fls dt3Tpl dominant phenotype.

“Therefore, dominant modifier loci are present in the WIK strain that buffer the expressivity of the fls dt3Tpl dominant phenotype.”

The fls te370f allele is a likely molecular null mutation because only a fragment of the ligand-binding domain is present while the transmembrane and cytoplasmic death domains are absent.

“This allele is a likely molecular null mutation as only a fragment of the ligand-binding domain is present while the transmembrane and cytoplasmic death domains, which are essential for function of this protein, are both absent.”

• AssumptionRests on an assumption: The transmembrane and cytoplasmic death domains of the Edar protein are essential for its function.

The fls dt3Tpl strong phenotype was partially suppressed when crossed with the polymorphic WIK mapping strain, indicating the presence of dominant modifier(s) in the WIK line.

“we found that the fls dt3Tpl “strong” phenotype was partially suppressed when crossed with the polymorphic WIK mapping strain indicating the presence of dominant modifier(s) in the WIK line (Table 1).”

Loss of Eda signaling in zebrafish causes a spectrum of phenotypes corresponding to those described for HED in humans.

“Loss of Eda signaling in the zebrafish causes a spectrum of phenotypes corresponding to those described for HED in humans”

Eda signaling has a previously unknown role in teleosts.

“We uncover a previously unknown role of Eda signaling in teleosts”

The zebrafish mutants may serve as a genetic model of HED.

“therefore the zebrafish mutants may serve as a genetic model of this disease.”

The segregation pattern of the two phenotypic classes of fls dt3Tpl suggests the presence of separate, unlinked modifier loci in the Tü background affecting the number of scales.

“The segregation pattern of the two phenotypic classes of fls dt3Tpl suggests the presence of separate, unlinked, modifier loci in the Tü background affecting the number of scales (Table 1 and data not shown).”

Adult genetic screens in zebrafish are useful in identifying essential developmental processes involved in human disease and morphological evolution.

“our findings point to the utility of adult genetic screens in the zebrafish in identifying essential developmental processes involved in human disease and in morphological evolution.”

The defects of the fins and scales are due to the role of Eda signaling in organizing epidermal cells into discrete signaling centers of the scale epidermal placode and fin fold.

“We find that the defects of the fins and scales are due to the role of Eda signaling in organizing epidermal cells into discrete signaling centers of the scale epidermal placode and fin fold.”

Nkt exposes a previously unknown dominant function of mutations in the eda gene since a true heterozygous condition is formed.

“Thus, Nkt exposes previously unknown dominant function of mutations in this gene since a true heterozygous condition is formed.”

There is a conserved developmental role of Edar between dermal scales of fish and mammalian hairs.

“This suggests that there is a conserved developmental role of Edar between dermal scales of fish and mammalian hairs.”

In the fin, Eda signaling directs late stages of fin development such as the formation and growth of the dermal rays.

“In the fin, Eda signaling directs late stages of fin development such as the formation and growth of the dermal rays.”

The function of Eda signaling is likely to maintain the growth permissive function of the fin fold through its regulation of a distal signaling center of individual rays.

“Given the expression of edar during fin development and the defects observed in the distal epidermis in the mutant, it is likely that the function of Eda signaling is to maintain the growth permissive function of the fin fold through its regulation of a distal signaling center of individual rays.”

The molecular mechanisms of Edar function are similar between fish and humans.

“These findings suggest that the molecular mechanisms of Edar function are similar between fish and humans.”

The stage of scale placode formation affected in fls closely resembles the pre-placode stage (P0-P1) of hair placode formation in the downless mouse mutant.

“This stage closely resembles the stage of scale placode formation that is affected in fls shown here.”

Analysis of shh and bmp2b expression in fls te370f indicated the necessity of edar function for their expression.

“Analysis of shh and bmp2b expression in fls te370f indicated the necessity of edar function for their expression (Figure 4F and H).”

The correlated effect in these zebrafish structures is due to a developmental role of Eda signaling in organizing epithelial cells into signaling centers.

“The correlated effect in these zebrafish structures is due to a developmental role of Eda signaling in organizing epithelial cells into signaling centers.”

The expression of shh and bmp2b has been shown to be within the basal epidermis overlying the forming lepidotrichia.

“The expression of shh and bmp2b has been shown to be within the basal epidermis overlying the forming lepidotrichia [31].”

• cites [31] L Laforest, 1998, Involvement of the sonic hedgehog, patched 1 and bmp2 genes in patterning of the zebrafish dermal fin rays., Development sourceNot checked — no full text of the source

The zebrafish eda gene is autosomal.

“The zebrafish eda gene is autosomal in the zebrafish.”

• AssumptionRests on an assumption: The zebrafish eda gene is autosomal.

Eda signaling in mammals and teleosts is conserved in the early phases of placode formation in controlling the functional continuity and signaling of the epidermal placode to orchestrate appendage formation.

“Thus, Eda signaling in mammals and teleosts is conserved in the early phases of placode formation in controlling the functional continuity and signaling of the epidermal placode to orchestrate appendage formation.”

The epithelial organization and function of the developing scale placode is dependent on edar.

“Further we find that the epithelial organization and function of the developing scale placode is dependent on edar.”

The dominance seen in Eda is probably not due to haploinsufficiency.

“Hemizygous wildtype condition in humans indicates that the dominance we see in Eda is probably not due to haploinsufficiency.”

Evidence for an early developmental role of the epidermis in induction or patterning of the teleost scale is lacking.

“evidence for an early developmental role of the epidermis in induction or patterning of the teleost scale is lacking.”

• cites [24] JY Sire, 1997, Scale development in zebrafish (Danio rerio)., J Anat sourceNot checked — no full text of the source

In scale development, Eda signaling is necessary for the basal epidermal cells to form a functional placode.

“In the case of scale development, Eda signaling is necessary for the basal epidermal cells to form a functional placode.”

The asymmetry of lepidotrichial development suggests that the fin rays have a specific regional identity to provide the shape and form of the fin.

“The asymmetry of lepidotrichial development suggests that, like the proximal endochondrial fin skeleton, the fin rays have a specific regional identity to provide the shape and form of the fin.”

The phenotype of both Nkt and fls demonstrates that Eda signaling is necessary for fin development.

“The phenotype of both Nkt and fls demonstrate that Eda signaling is necessary for fin development.”

These data support the notion that an epidermal placode is involved in dermal scale formation.

“These data support the notion that an epidermal placode is involved in dermal scale formation.”

The effect of loss of edar function on fin development uncovers an intrinsic developmental polarity of the late developing fish fin.

“The effect of loss of edar function on fin development uncovers an intrinsic developmental polarity of the late developing fish fin.”

These changes lead to viable changes in adult morphology.

“These changes lead to viable changes in adult morphology.”

Mutations affecting Eda signaling lead to impaired development of integumentary appendages of fish, birds, and man.

“Mutations affecting Eda signaling lead to impaired development of integumentary appendages of fish, birds, and man.”

The concomitant expression of edar, shh and bmp2b in both distal lepidotrichia development and during placode specification suggests that they work in concert to mediate the inductive and/or permissive effects of the epidermis, thus organizing signaling centers for the development of the dermal skeleton.

“The concomitant expression of edar, shh and bmp2b in both distal lepidotrichia development and during placode specification suggest that they work in concert to mediate the inductive and/or permissive effects of the epidermis – thus organizing signaling centers for the development of the dermal skeleton.”

A second developmental role of Eda signaling in the developing fin is observed in the outgrowth and patterning of the individual lepidotrichial rays, evidenced by expression of edar in the distal tip of the forming rays and distal epidermis.

“A second developmental role of Eda signaling in the developing fin is observed in the outgrowth and patterning of the individual lepidotrichial rays evidenced by expression of edar in the distal tip of the forming rays and distal epidermis.”

The downless mouse mutant, which has a mutation that disrupts the mouse Edar gene, causes arrest of placode formation at a pre-placode stage of development (P0-P1).

“They report that the downless mouse mutant, which has a mutation that disrupts the mouse Edar gene [36], causes arrest of placode formation at a pre-placode stage of development (P0–P1).”

• cites [36] DJ Headon, 1999, Involvement of a novel Tnf receptor homologue in hair follicle induction., Nat Genet sourceNot checked — no full text of the source

Eda signaling is necessary for the development and patterning of the dermal bones of the skull, scales, fin rays as well as teeth of the adult zebrafish.

“We show that Eda signaling is necessary for the development and patterning of the dermal bones of the skull, scales, fin rays as well as teeth of the adult zebrafish.”

The dorsal pitch of the caudal fin is an indirect effect of the mutation on swimming without fin rays.

“the dorsal pitch of the caudal fin is an indirect effect of the mutation on swimming without fin rays (amputated fins that fail to regenerate show similar morphology).”

The expression of edar in the distal lepidotrichial tips suggests a late developmental role of Eda signaling in regulating formation of the lepidotrichia in concert with shh and bmp2b.

“The expression of edar in the distal lepidotrichial tips suggests a late developmental role of Eda signaling in regulating formation of the lepidotrichia in concert with shh and bmp2b.”

A plausible mechanistic explanation for the observed dominance of Nkt is that the C-terminal truncation inhibits the function of the wild type protein in binding to Edar.

“Since EDA functions as a homotrimeric protein [46], a plausible mechanistic explanation for the observed dominance of Nkt is that the C-terminal truncation inhibits the function of the wild type protein in binding to Edar.”

• cites [46] S Ezer, 1999, Ectodysplasin is a collagenous trimeric type II membrane protein with a tumor necrosis factor-like domain and co-localizes with cytoskeletal structures at lateral and apical surfaces of cells., Hum Mol Genet sourceNot checked — no full text of the source

Eda signaling likely shares a common role in inductive signaling in tooth and skull development.

“Eda signaling likely shares a common role in inductive signaling in each of these diverse organs.”

Variation at these gene loci may act in concert to regulate number of dermal plates/scales.

“Thus variation at these gene loci may act in concert to regulate number of dermal plates/scales.”

Buffering of the phenotypic outcome that results from defective Eda signaling could be a common mechanism that permits viable and diverse phenotypes.

“Therefore, buffering of the phenotypic outcome that results from defective Eda signaling could be a common mechanism that permits viable and diverse phenotypes.”

Control of the level of Eda signaling in post-embryonic development is an essential component for the determination of the number and form of many different organ systems of the adult.

“These data indicate that control of the level of Eda signaling in post-embryonic development is an essential component for the determination of the number and form of many different organ systems of the adult.”

Our findings on the dose and organ specific sensitivity of Eda signaling in different structures of the zebrafish argues that evolution of this trait could result from a regulation of absolute levels of expression.

“Our findings on the dose and organ specific sensitivity of Eda signaling in different structures of the zebrafish argues that evolution of this trait could result from a regulation of absolute levels of expression.”

Recent evidence shows a significant association between the edar locus and dermal plate number in sticklebacks in addition to the predominant eda locus.

“Interestingly, recent evidence also shows a significant association between the edar locus and dermal plate number in sticklebacks in addition to the predominant eda locus [55].”

• cites [55] AK Knecht, 2007, Constraints on utilization of the EDA-signaling pathway in threespine stickleback evolution., Evol Dev sourceNot checked — no full text of the source

The graded effects seen in the expressivity of mutations affecting eda and edar point to a dose sensitive readout of the Eda signaling pathway that affects different organ systems with varied expressivity.

“The graded effects seen in the expressivity of mutations affecting eda and edar points to a dose sensitive readout of the Eda signaling pathway that affects different organ systems with varied expressivity.”

Evidence from the stickleback suggests that genetic variance at the eda locus underlies differences in the extent of dermal plate formation in diverged populations.

“Additionally, evidence from the stickleback, Gasterosteus aculeatus, suggests that genetic variance at the eda locus underlies differences in the extent of dermal plate formation in diverged populations of this species [33].”

• cites [33] PF Colosimo, 2005, Widespread parallel evolution in sticklebacks by repeated fixation of Ectodysplasin alleles., Science sourceNot checked — no full text of the source