Hydrocortisone (30–40 μg on day 10) and triamcinolone (10–20 ng on day 7–8) both inhibit or alter... more Hydrocortisone (30–40 μg on day 10) and triamcinolone (10–20 ng on day 7–8) both inhibit or alter morphogenesis of scales and feathers. However, there are marked temporal and region‐specific differences in the effects induced by these two glucocorticoids. Triamcinolone (TAC) is most teratogenic on day 7 or 8, inhibiting formation of spurs and feathers and inducing club feather formation. Hydrocortisone is most teratogenic later in development, on day 10. Unique hydrocortisone‐induced responses are complete inhibition of scutellate scale formation, bent feathers, and apteria around the external auditory meatus. Altered synthesis of keratin polypeptides follows inhibition of scale morphogenesis by hydrocortisone and TAC. These in vivo data suggest that heterogeneity of glucocorticoid binding occurs in embryonic chick metatarsal skin. Survival data indicate that TAC is 2,000 times more embryotoxic than hydrocortisone.
By reading, you can know the knowledge and things more, not only about what you get from people t... more By reading, you can know the knowledge and things more, not only about what you get from people to people. Book will be more trusted. As this the molecular and developmental biology of keratins, it will really give you the good idea to be successful. It is not only for you to be success in certain life you can be successful in everything. The success can be started by knowing the basic knowledge and do actions.
Triamcinolone acetonide (TAC), a long-acting synthetic glucocorticoid, markedly reduces survival ... more Triamcinolone acetonide (TAC), a long-acting synthetic glucocorticoid, markedly reduces survival rates in chick embryos when injected in small (10-100 ng) single-injection doses on days 5 or 9 of incubation. In addition to its embryotoxic effect, TAC causes such gross malformations as gastroschisis, reduced body weight, encephalocele, micrognathia, curled toes, and club feathers. These effects of TAC are more severe in 5-day-old chick embryos than in 9-day-old ones. A comparison with cortisol (hydrocortisone), a structurally similar, naturally occurring steroid, indicates that TAC is approximately 600 times more toxic in chick embryos than cortisol. TAC also inhibits differentation of the bursa of Fabricius: single injections on the chorioallantoic membrane (CAM) of 10-20 ng on day 5 or 9 reduced size and weight of this lymphoid organ. Histological examination showed a sharp reduction in the size and number of bursal follicles, a reduction in the number of lymphocytes within these follicles, and a degeneration of the epithelium covering bursal plicae.
The polyacrylamide gradient gel electrophoresis (PAGGE) pattern of polypeptides isolated from nor... more The polyacrylamide gradient gel electrophoresis (PAGGE) pattern of polypeptides isolated from normal scuttate scale epidermis of 1-week-old chicks was different from that of the anterior shank epidermis from 1-week-old scaleless mutant chicks. The PAGGE patterns of polypeptides isolated from normal and scaleless reticulate scale epidermis (from 1-week-old chicks) differed by only one band, whereas comparison of mutant's scuttate and reticulate patterns showed three band differences. These data are discussed in relation to the action of the scaleless gene on early morphogenesis of the two types of scales.
During normal chicken development tenascin begins to accumulate in the dermis of anterior metatar... more During normal chicken development tenascin begins to accumulate in the dermis of anterior metatarsal skin at the time of scutate scale ridge formation, and is localized in a distinct pattern along the outer scale surface. Anterior metatarsal skin from scaleless (sdsc) embryos, which do not form scutate scales, begins to accumulate tenascin 4 days later than normal skin. This study shows that normal and scaleless anterior metatarsal dermis accumulate the same tenascin isoforms and undergo the same isoform changes in the post-hatch period, but there is less tenascin accumulated in scaleless dermis and there is no pattern to its distribution. In both normal and scaleless anterior metatarsal skin, tenascin mFWA is localized in the dermis and is distributed in the same way as the protein. Thus, scaleless skin is defective in the ability to accumulate appropriate amounts of tenascin and to maintain the tenascin in the patterned manner of normal. Recombinant skin cultures show that epidermal-dermal interactions are required for tenascin accumulation. The dermis specifies the way that tenascin is organized, but interaction with epidermis is required to maintain this organization. The epidermal role appears to be permissive because in heterotypic recombinants, neither scaleless anterior metatarsal epidermis nor normal footpad epidermis changes the way that tenascin appears in the normal anterior metatarsal dermis; and in reciprocal recombinants, normal anterior metatarsal epidermis does not change the way tenascin is accumulated in either scaleless anterior metatarsal dermis or normal footpad dermis.
Embryonic induction has been demonstrated in numerous studies, yet the molecular basis for induct... more Embryonic induction has been demonstrated in numerous studies, yet the molecular basis for induction still eludes investigators. Components of the extracellular matrix (ECM), cell adhesion molecules (CAM), diffusable factors, as well as direct cell-cell contact, have been implicated in the early induction of avian feathers and scales. Although feathers and scales differ in many aspects, they are similar in that they appear initially as discrete and orderly arranged epidermal placodes. In the case of scutate scales, the cells of the epidermal placode are nonproliferative, while the cells of the interplacode regions are highly proliferative. In this study, I compare the proliferative activity of normal scale cells with that of the epidermal cells from embryos of the scaleless (sclsc) mutant chicken which does not undergo epidermal placode formation and therefore lacks scutate scales. These results show that prior to the time that placodes would normally form, the proliferative activity of the scaleless epidermal cells is similar to that seen in normal epidermal cells. Likewise, the cessation of cell proliferation seen in normal placodes occurs in the epidermal basal cells of the sc/sc shank. It is the high rate of proliferation seen for the epidermal basal cells of the normal interplacode region and the outer surface of the scale ridge that never develops in the sc/sc epidermal cells.
Morphogenesis of the anterior metatarsal skin (scutate scale region), from 9.5 to 12 days of deve... more Morphogenesis of the anterior metatarsal skin (scutate scale region), from 9.5 to 12 days of development, results in the formation of orderly patterned scale ridges. It is after the initial formation of the Definitive Scale Ridge that the characteristic outer and inner epidermal surfaces differentiate. The hard, plate-like beta stratum, with its unique beta keratins, characterizes the epidermis of the outer surface, while the epidermis of the inner surface elaborates an alpha stratum. The anterior metatarsal region of the scaleless mutant does not undergo scale morphogenesis. Therefore, scale ridges do not form nor do the outer and inner epidermal surfaces with their characteristic beta and alpha strata. We have found that the extracellular matrix molecule, tenascin, first appears in the scutate scale dermis at 12 days of development when the scale ridge is established. Tenascin is found in the dermis only under the scale ridge and is not associated with the dermal-epidermal junction. Tenascin is not found in scaleless anterior metatarsal dermis at this time. As outgrowth of the Definitive Scale Ridge takes place, tenascin distribution correlates closely with the formation of the outer epidermal surface of each scale ridge. By 16 days of development tenascin is also found in close association with the dermal-epidermal junction. Tenascin does not appear in scaleless anterior metatarsal dermis until 16 days of development and then it is randomly and sparsely distributed at the dermal-epidermal junction. Tenascin's initial appearance and pattern of distribution in the scutate scale dermis and its abnormal expression in the scaleless dermis suggest that morphogenesis plays a significant role in regulation of its expression.
In Combination with dermis from the a n t e r i o r shank skin of the scaleless mutant, the chori... more In Combination with dermis from the a n t e r i o r shank skin of the scaleless mutant, the chorionic epithelium forms an epidermis whose ul trastructural features a r e indistinguishable from those seen along the inner surface of normal scales and along the a n t e r i o r shank of the scaleless m u t a n t .
Journal of Experimental Marine Biology and Ecology, Feb 1, 1981
The developmental biology of the loggerhead sea turtle. fu~tto t'uref& (Link). was investigated i... more The developmental biology of the loggerhead sea turtle. fu~tto t'uref& (Link). was investigated in the field on Ossabaw Island (Georgia). anil in the laboratory. Hatching success in wild. untouched nests was OTjC;::,; for successfully transplanted nests it was 75.8",,: for nests transported to a hatchery tent, X??,,; while for those transported to the laboratory and incubated under controlled conditions it was 95",,. Mean clutch sizes and incubation times are presented. Gross inspection of unhatched hatchery eggs showed >90",, fertility in the nests. Using laboratory eggs, we find that sea turtle development closely follows that described for the freshwater turtle C'hel~lru serprntina (Link). Early fusion of the amnion with the chorionic membrane is evident. and disruption of the organization 01 these extra-embryonic membranes may be related to decreased viability and the low hatch rates reported for hatchery conditions.
The avian integument is uniquely characterized by the presence of feathers, whose distribution, s... more The avian integument is uniquely characterized by the presence of feathers, whose distribution, structure and development have been reviewed recently on a comparative basis by Lucas and Stettenheim (1972). Brush (1974, 1975, 1980) and Brush and Wyld (1982) have used the biochemical composition of feathers in comparative and evolutionary studies of several bird species. In general, the body of most birds appears covered by feathers with obvious naked areas restricted to the feet, beak, comb and wattle. However, as discussed by Lucas and Stettenheim (1972) and Stettenheim (1972) feathers occur in tracts (pterylae) on most birds, which are separated by naked regions of skin known as apteria. The apteria may exist within individual feather tracts as the naked skin between feathers or between pterylae. In the developing chicken skin, Sengel (1976) distinguished two types of apteric regions; one which is entirely devoid of feathers (for example, the midventral apterium) and one which develops a few loosely distributed down feathers (for example, the apterium between the breast and ventral pterylae). This distinction is of importance in developmental studies where one is interested in the control of appendage formation. In a later section we will discuss some of the more recent findings on the development and structure of feathers, with special reference to the localization of keratins with indirect immunofluorescence, using non-cross-reacting antisera to both α -and s-(feather) keratins.
... elsewhere (O'Guin and Sawyer, '82). SCM-alpha keratin isolated from... more ... elsewhere (O'Guin and Sawyer, '82). SCM-alpha keratin isolated from the ante-rior metatarsal epidermis of 12-day-old scale-less (Abbott and Asmundson, '57) mutant hatchlings (Fig. 1A) and SCM-beta keratin ex-tracted from neonatal down feathers (White Leghorn hatchlings ...
In addition to containing microtubule and microfilament systems, vertebrate epithelial cells cont... more In addition to containing microtubule and microfilament systems, vertebrate epithelial cells contain an elaborate keratin intermediate-filament cytoskeleton . Little is known about its structural organization or function . Using indirect immunofluorescence microscopy with an antikeratin antiserum probe, we found that destabilization of microtubules and microfilaments with cytostatic drugs induces significant alterations in the cytoskeletal organization of keratin filaments in HeLa and fetal mouse epidermal cells . Keratin filament organization was observed to undergo a rapid (1-2 h) transition from a uniform distribution to an open lattice of keratin fibers stabilized by membrane-associated focal centers . Since addition of any one drug alone did not elicit significant organizational change in the keratin cytoskeleton, we suggest that microfilaments and microtubules have a combined role in maintaining the arrangement of keratin in these cells . Vimentin filaments, the only other intermediatesized filaments found in HeLa cells, did not co-distribute with keratin in untreated or drugtreated cells . These findings offer a new way to approach the study of the dynamics and functional roles of the keratin cytoskeleton in epithelial cells . The structure and function of the vertebrate cytoskeleton are dependent upon three major groups of polymers : microtubules, microfilaments, and intermediate filaments . Unlike microtubules and microfilaments, whose distributions are universal in vertebrate cells and whose functions are well characterized (1-4), intermediate filaments are generally restricted in distribution to specific cell types, and their functions remain unresolved . Lazarides (5) has suggested that they participate in the organization and mechanical integration of the cytoplasm . Attention has recently focused on elucidating the structure, function, and organization of keratins in epithelial cells, particularly their utilization as elements of an intermediate-filament cytoskeleton where they are designated `cytokeratins' (7-10) . Keratin filament organization has been shown to be remarkably stable in epithelial cells in vitro by immunological methods . Microinjection of anti-a-keratin antibodies into epithelial cells has been used to directly alter the organization of the keratin cytoskeleton . However, no biochemical inhibitors analogous to cytostatic drugs used to destabilize microtubules or microfilaments have been found that specifically interfere with cytokeratin structure or 1788
Rotation-mediated aggregation was used to test the capacity of early embryonic tongue cells from ... more Rotation-mediated aggregation was used to test the capacity of early embryonic tongue cells from different regions of the tongue to reorganize histotypically and terminally differentiate in vitro. Cells dissociated from the anterior ventral (AV) or posterior ventral (PV) surface of the 12 day embryonic tongue were cultured 6 days, fixed, and embedded in paraffin. Indirect immunofluorescence microscopy was used to demonstrate the occurrence and distribution of p-keratins, the presence of which represented regional and differentiation specific markers of late tongue development. Aggregates of AV cells were organized into a P-keratin-producing stratified epithelium. Similar PV aggregates formed only an a-keratin-producing stratified epithelium. The epithelial cells of these tongue tissue constructs expressed a-and p-keratins in a manner consistent with the temporal and histotypical expression of keratins observed in vivo. MATERIALS AND METHODS Histology and immunocytochemistrg The anterior ventral (lingual nail) and posterior ventral regions were obtained from whole tongues dissected from 12 and 16 day embryonic White Leghorn chickens (Callus domesticus). These tissues were fixed in ethanokacetic acid struct embryonic tongue tissue in vitro from a mixture of single cells (Townes and Holtfreter, '55; Moscona and Garber, '68; Steinberg, '70; Manand Moscona7 '79; Knapp and Sawyer, '82' '83).
Gene co-expression network analysis has been a research method widely used in systematically expl... more Gene co-expression network analysis has been a research method widely used in systematically exploring gene function and interaction. Using the Weighted Gene Coexpression Network Analysis (WGCNA) approach to construct a gene co-expression network using data from a customized 44K microarray transcriptome of chicken epidermal embryogenesis, we have identified two distinct modules that are highly correlated with scale or feather development traits. Signaling pathways related to feather development were enriched in the traditional KEGG pathway analysis and functional terms relating specifically to embryonic epidermal development were also enriched in the Gene Ontology analysis. Significant enrichment annotations were discovered from customized enrichment tools such as Modular Single-Set Enrichment Test (MSET) and Medical Subject Headings (MeSH). Hub genes in both trait-correlated modules showed strong specific functional enrichment toward epidermal development. Also, regulatory elements, such as transcription factors and miRNAs, were targeted in the significant enrichment result. This work highlights the advantage of this methodology for functional prediction of genes not previously associated with scale-and feather trait-related modules.
Hydrocortisone (30–40 μg on day 10) and triamcinolone (10–20 ng on day 7–8) both inhibit or alter... more Hydrocortisone (30–40 μg on day 10) and triamcinolone (10–20 ng on day 7–8) both inhibit or alter morphogenesis of scales and feathers. However, there are marked temporal and region‐specific differences in the effects induced by these two glucocorticoids. Triamcinolone (TAC) is most teratogenic on day 7 or 8, inhibiting formation of spurs and feathers and inducing club feather formation. Hydrocortisone is most teratogenic later in development, on day 10. Unique hydrocortisone‐induced responses are complete inhibition of scutellate scale formation, bent feathers, and apteria around the external auditory meatus. Altered synthesis of keratin polypeptides follows inhibition of scale morphogenesis by hydrocortisone and TAC. These in vivo data suggest that heterogeneity of glucocorticoid binding occurs in embryonic chick metatarsal skin. Survival data indicate that TAC is 2,000 times more embryotoxic than hydrocortisone.
By reading, you can know the knowledge and things more, not only about what you get from people t... more By reading, you can know the knowledge and things more, not only about what you get from people to people. Book will be more trusted. As this the molecular and developmental biology of keratins, it will really give you the good idea to be successful. It is not only for you to be success in certain life you can be successful in everything. The success can be started by knowing the basic knowledge and do actions.
Triamcinolone acetonide (TAC), a long-acting synthetic glucocorticoid, markedly reduces survival ... more Triamcinolone acetonide (TAC), a long-acting synthetic glucocorticoid, markedly reduces survival rates in chick embryos when injected in small (10-100 ng) single-injection doses on days 5 or 9 of incubation. In addition to its embryotoxic effect, TAC causes such gross malformations as gastroschisis, reduced body weight, encephalocele, micrognathia, curled toes, and club feathers. These effects of TAC are more severe in 5-day-old chick embryos than in 9-day-old ones. A comparison with cortisol (hydrocortisone), a structurally similar, naturally occurring steroid, indicates that TAC is approximately 600 times more toxic in chick embryos than cortisol. TAC also inhibits differentation of the bursa of Fabricius: single injections on the chorioallantoic membrane (CAM) of 10-20 ng on day 5 or 9 reduced size and weight of this lymphoid organ. Histological examination showed a sharp reduction in the size and number of bursal follicles, a reduction in the number of lymphocytes within these follicles, and a degeneration of the epithelium covering bursal plicae.
The polyacrylamide gradient gel electrophoresis (PAGGE) pattern of polypeptides isolated from nor... more The polyacrylamide gradient gel electrophoresis (PAGGE) pattern of polypeptides isolated from normal scuttate scale epidermis of 1-week-old chicks was different from that of the anterior shank epidermis from 1-week-old scaleless mutant chicks. The PAGGE patterns of polypeptides isolated from normal and scaleless reticulate scale epidermis (from 1-week-old chicks) differed by only one band, whereas comparison of mutant's scuttate and reticulate patterns showed three band differences. These data are discussed in relation to the action of the scaleless gene on early morphogenesis of the two types of scales.
During normal chicken development tenascin begins to accumulate in the dermis of anterior metatar... more During normal chicken development tenascin begins to accumulate in the dermis of anterior metatarsal skin at the time of scutate scale ridge formation, and is localized in a distinct pattern along the outer scale surface. Anterior metatarsal skin from scaleless (sdsc) embryos, which do not form scutate scales, begins to accumulate tenascin 4 days later than normal skin. This study shows that normal and scaleless anterior metatarsal dermis accumulate the same tenascin isoforms and undergo the same isoform changes in the post-hatch period, but there is less tenascin accumulated in scaleless dermis and there is no pattern to its distribution. In both normal and scaleless anterior metatarsal skin, tenascin mFWA is localized in the dermis and is distributed in the same way as the protein. Thus, scaleless skin is defective in the ability to accumulate appropriate amounts of tenascin and to maintain the tenascin in the patterned manner of normal. Recombinant skin cultures show that epidermal-dermal interactions are required for tenascin accumulation. The dermis specifies the way that tenascin is organized, but interaction with epidermis is required to maintain this organization. The epidermal role appears to be permissive because in heterotypic recombinants, neither scaleless anterior metatarsal epidermis nor normal footpad epidermis changes the way that tenascin appears in the normal anterior metatarsal dermis; and in reciprocal recombinants, normal anterior metatarsal epidermis does not change the way tenascin is accumulated in either scaleless anterior metatarsal dermis or normal footpad dermis.
Embryonic induction has been demonstrated in numerous studies, yet the molecular basis for induct... more Embryonic induction has been demonstrated in numerous studies, yet the molecular basis for induction still eludes investigators. Components of the extracellular matrix (ECM), cell adhesion molecules (CAM), diffusable factors, as well as direct cell-cell contact, have been implicated in the early induction of avian feathers and scales. Although feathers and scales differ in many aspects, they are similar in that they appear initially as discrete and orderly arranged epidermal placodes. In the case of scutate scales, the cells of the epidermal placode are nonproliferative, while the cells of the interplacode regions are highly proliferative. In this study, I compare the proliferative activity of normal scale cells with that of the epidermal cells from embryos of the scaleless (sclsc) mutant chicken which does not undergo epidermal placode formation and therefore lacks scutate scales. These results show that prior to the time that placodes would normally form, the proliferative activity of the scaleless epidermal cells is similar to that seen in normal epidermal cells. Likewise, the cessation of cell proliferation seen in normal placodes occurs in the epidermal basal cells of the sc/sc shank. It is the high rate of proliferation seen for the epidermal basal cells of the normal interplacode region and the outer surface of the scale ridge that never develops in the sc/sc epidermal cells.
Morphogenesis of the anterior metatarsal skin (scutate scale region), from 9.5 to 12 days of deve... more Morphogenesis of the anterior metatarsal skin (scutate scale region), from 9.5 to 12 days of development, results in the formation of orderly patterned scale ridges. It is after the initial formation of the Definitive Scale Ridge that the characteristic outer and inner epidermal surfaces differentiate. The hard, plate-like beta stratum, with its unique beta keratins, characterizes the epidermis of the outer surface, while the epidermis of the inner surface elaborates an alpha stratum. The anterior metatarsal region of the scaleless mutant does not undergo scale morphogenesis. Therefore, scale ridges do not form nor do the outer and inner epidermal surfaces with their characteristic beta and alpha strata. We have found that the extracellular matrix molecule, tenascin, first appears in the scutate scale dermis at 12 days of development when the scale ridge is established. Tenascin is found in the dermis only under the scale ridge and is not associated with the dermal-epidermal junction. Tenascin is not found in scaleless anterior metatarsal dermis at this time. As outgrowth of the Definitive Scale Ridge takes place, tenascin distribution correlates closely with the formation of the outer epidermal surface of each scale ridge. By 16 days of development tenascin is also found in close association with the dermal-epidermal junction. Tenascin does not appear in scaleless anterior metatarsal dermis until 16 days of development and then it is randomly and sparsely distributed at the dermal-epidermal junction. Tenascin's initial appearance and pattern of distribution in the scutate scale dermis and its abnormal expression in the scaleless dermis suggest that morphogenesis plays a significant role in regulation of its expression.
In Combination with dermis from the a n t e r i o r shank skin of the scaleless mutant, the chori... more In Combination with dermis from the a n t e r i o r shank skin of the scaleless mutant, the chorionic epithelium forms an epidermis whose ul trastructural features a r e indistinguishable from those seen along the inner surface of normal scales and along the a n t e r i o r shank of the scaleless m u t a n t .
Journal of Experimental Marine Biology and Ecology, Feb 1, 1981
The developmental biology of the loggerhead sea turtle. fu~tto t'uref& (Link). was investigated i... more The developmental biology of the loggerhead sea turtle. fu~tto t'uref& (Link). was investigated in the field on Ossabaw Island (Georgia). anil in the laboratory. Hatching success in wild. untouched nests was OTjC;::,; for successfully transplanted nests it was 75.8",,: for nests transported to a hatchery tent, X??,,; while for those transported to the laboratory and incubated under controlled conditions it was 95",,. Mean clutch sizes and incubation times are presented. Gross inspection of unhatched hatchery eggs showed >90",, fertility in the nests. Using laboratory eggs, we find that sea turtle development closely follows that described for the freshwater turtle C'hel~lru serprntina (Link). Early fusion of the amnion with the chorionic membrane is evident. and disruption of the organization 01 these extra-embryonic membranes may be related to decreased viability and the low hatch rates reported for hatchery conditions.
The avian integument is uniquely characterized by the presence of feathers, whose distribution, s... more The avian integument is uniquely characterized by the presence of feathers, whose distribution, structure and development have been reviewed recently on a comparative basis by Lucas and Stettenheim (1972). Brush (1974, 1975, 1980) and Brush and Wyld (1982) have used the biochemical composition of feathers in comparative and evolutionary studies of several bird species. In general, the body of most birds appears covered by feathers with obvious naked areas restricted to the feet, beak, comb and wattle. However, as discussed by Lucas and Stettenheim (1972) and Stettenheim (1972) feathers occur in tracts (pterylae) on most birds, which are separated by naked regions of skin known as apteria. The apteria may exist within individual feather tracts as the naked skin between feathers or between pterylae. In the developing chicken skin, Sengel (1976) distinguished two types of apteric regions; one which is entirely devoid of feathers (for example, the midventral apterium) and one which develops a few loosely distributed down feathers (for example, the apterium between the breast and ventral pterylae). This distinction is of importance in developmental studies where one is interested in the control of appendage formation. In a later section we will discuss some of the more recent findings on the development and structure of feathers, with special reference to the localization of keratins with indirect immunofluorescence, using non-cross-reacting antisera to both α -and s-(feather) keratins.
... elsewhere (O'Guin and Sawyer, '82). SCM-alpha keratin isolated from... more ... elsewhere (O'Guin and Sawyer, '82). SCM-alpha keratin isolated from the ante-rior metatarsal epidermis of 12-day-old scale-less (Abbott and Asmundson, '57) mutant hatchlings (Fig. 1A) and SCM-beta keratin ex-tracted from neonatal down feathers (White Leghorn hatchlings ...
In addition to containing microtubule and microfilament systems, vertebrate epithelial cells cont... more In addition to containing microtubule and microfilament systems, vertebrate epithelial cells contain an elaborate keratin intermediate-filament cytoskeleton . Little is known about its structural organization or function . Using indirect immunofluorescence microscopy with an antikeratin antiserum probe, we found that destabilization of microtubules and microfilaments with cytostatic drugs induces significant alterations in the cytoskeletal organization of keratin filaments in HeLa and fetal mouse epidermal cells . Keratin filament organization was observed to undergo a rapid (1-2 h) transition from a uniform distribution to an open lattice of keratin fibers stabilized by membrane-associated focal centers . Since addition of any one drug alone did not elicit significant organizational change in the keratin cytoskeleton, we suggest that microfilaments and microtubules have a combined role in maintaining the arrangement of keratin in these cells . Vimentin filaments, the only other intermediatesized filaments found in HeLa cells, did not co-distribute with keratin in untreated or drugtreated cells . These findings offer a new way to approach the study of the dynamics and functional roles of the keratin cytoskeleton in epithelial cells . The structure and function of the vertebrate cytoskeleton are dependent upon three major groups of polymers : microtubules, microfilaments, and intermediate filaments . Unlike microtubules and microfilaments, whose distributions are universal in vertebrate cells and whose functions are well characterized (1-4), intermediate filaments are generally restricted in distribution to specific cell types, and their functions remain unresolved . Lazarides (5) has suggested that they participate in the organization and mechanical integration of the cytoplasm . Attention has recently focused on elucidating the structure, function, and organization of keratins in epithelial cells, particularly their utilization as elements of an intermediate-filament cytoskeleton where they are designated `cytokeratins' (7-10) . Keratin filament organization has been shown to be remarkably stable in epithelial cells in vitro by immunological methods . Microinjection of anti-a-keratin antibodies into epithelial cells has been used to directly alter the organization of the keratin cytoskeleton . However, no biochemical inhibitors analogous to cytostatic drugs used to destabilize microtubules or microfilaments have been found that specifically interfere with cytokeratin structure or 1788
Rotation-mediated aggregation was used to test the capacity of early embryonic tongue cells from ... more Rotation-mediated aggregation was used to test the capacity of early embryonic tongue cells from different regions of the tongue to reorganize histotypically and terminally differentiate in vitro. Cells dissociated from the anterior ventral (AV) or posterior ventral (PV) surface of the 12 day embryonic tongue were cultured 6 days, fixed, and embedded in paraffin. Indirect immunofluorescence microscopy was used to demonstrate the occurrence and distribution of p-keratins, the presence of which represented regional and differentiation specific markers of late tongue development. Aggregates of AV cells were organized into a P-keratin-producing stratified epithelium. Similar PV aggregates formed only an a-keratin-producing stratified epithelium. The epithelial cells of these tongue tissue constructs expressed a-and p-keratins in a manner consistent with the temporal and histotypical expression of keratins observed in vivo. MATERIALS AND METHODS Histology and immunocytochemistrg The anterior ventral (lingual nail) and posterior ventral regions were obtained from whole tongues dissected from 12 and 16 day embryonic White Leghorn chickens (Callus domesticus). These tissues were fixed in ethanokacetic acid struct embryonic tongue tissue in vitro from a mixture of single cells (Townes and Holtfreter, '55; Moscona and Garber, '68; Steinberg, '70; Manand Moscona7 '79; Knapp and Sawyer, '82' '83).
Gene co-expression network analysis has been a research method widely used in systematically expl... more Gene co-expression network analysis has been a research method widely used in systematically exploring gene function and interaction. Using the Weighted Gene Coexpression Network Analysis (WGCNA) approach to construct a gene co-expression network using data from a customized 44K microarray transcriptome of chicken epidermal embryogenesis, we have identified two distinct modules that are highly correlated with scale or feather development traits. Signaling pathways related to feather development were enriched in the traditional KEGG pathway analysis and functional terms relating specifically to embryonic epidermal development were also enriched in the Gene Ontology analysis. Significant enrichment annotations were discovered from customized enrichment tools such as Modular Single-Set Enrichment Test (MSET) and Medical Subject Headings (MeSH). Hub genes in both trait-correlated modules showed strong specific functional enrichment toward epidermal development. Also, regulatory elements, such as transcription factors and miRNAs, were targeted in the significant enrichment result. This work highlights the advantage of this methodology for functional prediction of genes not previously associated with scale-and feather trait-related modules.
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Papers by Roger Sawyer