Modification of human prekeratin during epidermal differentiation.

The polypeptide-chain components of human epidermal prekeratin and keratin were analysed by high-resolution SDS (sodium dodecyl sulphate)/polyacrylamide-gradient-gel electrophoresis. Size heterogeneity existed amongst prekeratin components and at least ten polypeptides, in the molecular-weight range 46,000-70,000, were observed in 0.1 M-citric acid/sodium citrate buffer (pH 2.65) extracts of scale epidermis. Prekeratin from scalp pilosebaceous ducts was identical with that from the contiguous epidermis, and no prekeratin was found in extracts of scale dermis. Prekeratin from plantar epidermis contained additional polypeptide chains, but only slight anatomical variation existed between the non-callus sites examined. Keratin differed from prekeratin in at least two major respects: (a) many major components did not co-electrophorese on high-resolution SDS/polyacrylamide slab gels, and (b) keratin, but not prekeratin, required denaturing and reducing conditions for extraction. Keratin extracted from scale epidermis after complete removal of prekeratin was identical with forearm stratum-corneum keratin. Palmar and plantar keratin contained additional polypeptide chains and had a different size distribution compared with forearm and scalp keratin components. Modification of prekeratin components to produce the keratin polypeptide profile occurred during epidermal differentiation, and these changes appeared to take place in the granular-layer region of the epidermis.     

Two polypeptide chain constituents of the major protein of the cornified layer of newborn rat epidermis.

The insoluble component of stratum corneum of rat epidermis yields two major bands after extraction with 8 M urea-mercaptoethanol-dithiothreitol. The ratio of these two bands is about 1:1 in terms of protein stain intensity and S-[14C]carboxymethyl label. Both polypeptides were purified to homogeneity by DE-52-cellulose, sodium dodecyl sulfate hydroxylapatite C column chromatography, and preparative DodSO4-polyacrylamide gel electrophoresis. The heavier polypeptide contains 30% alpha helix and the lighter contains 27% alpha helix as determined by circular dichroism studies. Both are sensitive to Pronase and resistant to trypsin, collagenase, and elastase. The lighter chain is stable to pepsin but the heavier can be partially degraded to a smaller polypeptide with a molecular weight similar to that of light chain. Amino acid analysis shows that the light chain contains 12 more tyrosine residues than does the heavy chain, suggesting that the light chain is not generated from the heavy chain. However, the two chains may have a common peptide region. Antiserum prepared against the heavier polypeptide can be completely absorbed by purified lighter polypeptide and vice versa indicating that both chains have some common antigenic determinants. Antibody against either chain can cross-react with the stratum corneum and keratohyalin granules in the epidermis of newborn rat as indicated by fluorescent microscopic observation. Similarly, this antibody also cross-reacts with the cell surface or the contents of spinous and granular cells, and very weakly with basal cells, indicating that the two proteins may be present in the lower strata as well as the stratum corneum.     

Differentiation of human scalp hair follicle keratinocytes in culture

The morphology of human scalp hair follicle keratinocytes, cultured on the bovine eye lens capsule, is studied by light and electron microscopy. The hair follicle keratinocytes in the stratified cultures are characterized by the presence of numerous tonofilaments, desmosomes and lysosomes and by the presence of glycogen accumulations. The cells in the upper layers develop a cornified envelope. Moreover, an incomplete basal lamina is found between the capsule and the basal cells. However, some features of epidermal keratinocytes in vivo, such as keratohyalin granules and stratum corneum formation, are absent. Analysis of the polypeptides by sodium dodecylsulfate polyacrylamide gel electrophoresis also reveals differences between the cultured hair follicle cells and epidermis, whilst the patterns of cultured cells and hair follicle sheaths are similar. The morphological and protein biosynthetic aspects of terminal differentiation of the keratinocytes in vitro are correlated. These results are discussed in the light of the findings with cultured epidermal keratinocytes, reported in the literature.     

Isolation and characterization of desmosome-associated tonofilaments from rat intestinal brush border

Epithelial cells of the small intestine, like those of other internal organs, contain intermediate-sized filaments immunologically related to epidermal prekeratin which are especially concentrated in the cell apex. Brush-order fractions were isolated from rat small intestine, and apical tonofilaments attached to desmosomal plaques and terminal web residues were prepared therefrom by extraction in high salt (1.5 M KCl) buffer and Triton X-100. The structure of these filaments was indistinguishable from that of epidermal tonofilaments and, as with epidermal prekeratin, filaments could be reconstituted from solubilized, denatured intestinal tonofilament protein. On SDS polyacrylamide gel electrophoresis of proteins of the extracted desmosome-tonofilament fractions, a number of typical brush-border proteins were absent or reduced, and enrichment of three major polypeptides of Mr 55,000, 48,000, and 40,000 was noted. On two- dimensional gel electrophoresis, the three enriched major polypeptides usually appeared as pairs of isoelectric variants, and the two smaller components (Mr 48,000, and 40,000) were relatively acidic (isoelectric pH values of 5.40 and below), compared to the Mr 55,000 protein which focused at pH values higher than 6.4. The tonofilament proteins were shown to be immunologically related to epidermal prekeratin by immunoreplica and blotting techniques using antibodies to bovine epidermal prekeratins. Similar major polypeptides were found in desmosome-attached tonofilaments from small intestine of mouse and cow. However, comparisons with epidermal tissues of cow and rat showed that all major polypeptides of intestinal tonofilaments were different from the major prekeratin polypeptides of epidermal tonofilaments. The results present the first analysis of a defined fraction of tonofilaments from a nonepidermal cell. The data indicate that structurally identical tonofilaments can be formed, in different types of cells, by different polypeptides of the cytokeratin family of proteins and that tonofilaments of various epithelia display tissue- specific patterns of their protein subunits.     

Keratin filaments of cultured human epidermal cells. Formation of intermolecular disulfide bonds during terminal differentiation.

Human epidermal cells grown in culture synthesize abundant keratins. These keratins are similar to those of stratum corneum of human epidermal callus in their insolubility in dilute aqueous buffers, their molecular weight range of 40,000 to 60,000, their immunolgical reactivity, and their ability to assemble into 80 A tonofilaments in vitro; but there are differences in the molecular weights of some of the proteins, the number of components, and their charge heterogeneity, related at least in part to phosphorylation. About 30% of all the proteins of living cultured keratinocytes consists of keratins, compared with over 85% of stratum corneum. All the keratins of human stratum corneum were found to be cross-linked by intermolecular disulfide bonds while most keratins of the living cells were not. As the cells mature in Methocel-stabilized suspension culture, their keratins become increasingly disulfide cross-linked. When uncross-linked tonofilaments of living keratinocytes are dissolved in 8 M urea and the filaments reconstituted in vitro their keratins become disulfide cross-linked under aerobic conditions and consequently insoluble in solutions of 8 M urea or sodium dodecyl sulfate. The results indicate that the uncross-linked state of the keratins in living cells is due to the reducing intracellular environment and not to a precursor state related to the primary structure of the proteins. The disulfide cross-links stabilizing the keratin filaments must be distinguished from the epsilon-(gamma-glutamyl)lysine cross-links stabilizing the cornified cell envelope.     

Structure and biochemical composition of desmosomes and tonofilaments isolated from calf muzzle epidermis

Complexes of plasma membrane segments with desmosomes and attached tonofilaments were separated from the stratum spinosum cells of calf muzzle by means of moderately alkaline buffers of low ionic strength and mechanical homogenization. These structures were further fractionated by the use of various treatments including sonication, sucrose gradient centrifugation, and extraction with buffers containing high concentrations of salt, urea, citric acid, or detergents. Subfractions enriched in desmosome-tonofilament-complexes and tonofilament fragments were studied in detail. The desmosome structures such as the midline, the trilaminar membrane profile, and the desmosomal plaque appeared well preserved and were notably resistant to the various treatments employed. Fractions containing desmosome- tonofilament complexes were invariably dominated by the nonmembranous proteins of the tonofilaments which appeared as five major polypeptide bands (apparent molecular weights: 48,000; 51,000; 58,000; 60,000; 68,000) present in molar ratios of approx. 2:1:1:2:2. Four of these polypeptide bands showed electrophoretic mobilities similar to those of prekeratin polypeptides from bovine hoof. However, the largest polypeptide (68,000 mol wt) migrated significantly less in polyacrylamide gels than the largest component of the hoof prekeratin (approximately 63,000 mol wt). In addition, a series of minor bands, including carbohydrate-containing proteins, were identified and concluded to represent constituents of the desmosomal membrane. The analysis of protein-bound carbohydrates (total 270 microgram/mg phospholipid in desmosome-enriched subfractions) showed the presence of relatively high amounts of glucosamine, mannose, galactose, and sialic acids. These data as well as the lipid composition (e.g., high ratio of cholesterol to phospholipids, relatively high contents of sphingomyelin and gangliosides, and fatty acid pattern) indicate that the desmosomal membrane is complex in protein and lipid composition and has a typical plasma membrane character. The similarity of the desmosome-associated tonofilaments to prekeratin filaments and other forms of intermediate- sized filaments is discussed.     

The polypeptide composition of bovine epidermal alpha-keratin.

1. The polypedtide chains that comprise the subunits of the tonofilaments, or th alpha-keratin component, of bovine epidermis were fractionated by combination of chromatography on DEAE-cellulose and preparative polyacrylamide-gel electrophoresis. 2. The seve polypeptide chains investigated had generalyy similar properties; all contained two residues per molecule of tryptophan and N-acetylserine was the common N-terminal amino acid residue. 3. On the basis of close similarities in alpha-helix content and amino acid composition, the polypeptide chains were classified into three distinct groups. Each group contained approximately one-third of the total polypeptides on a molar basis. The groups and designated polypeptides chain numbers were: group one, polypeptides 1a and 1b, which had moleculae weights of 58,000, contained about 25% alpha-helix, 86 glutamic acid and 8 cysteine residues per molecule, but which differed in net charge, extinction coefficients and tyrosine contents; group two, polypeptides 2, 3, and 4, which hadmolecular weights within thewithin the range of 52,00-56,000, contained about 48% alpha-helix, 54 glutamic acid and 6 cysteine residues per molecule, but which differed in extinction coefficients and tryosine contents; and group, polypeptides 5 and 6, which had molecular weights of 47000-48000, contained about 56% alpha-helix, 64 glutamic acid and 4 cysteine residues per molecule, but which differed in extinction coefficients and tyrosine contents...     

Prekeratin biosynthesis in human scalp epidermis.

Analysis of human scalp epidermal prekeratin polypeptides by two-dimensional gel electrophoresis revealed that each of the bands observed in one-dimensional electrophoresis consisted of three to five polypeptides of the same molecular weight but differing in isoelectric points. It was possible to divide the polypeptides into two families, with isoelectric points in the ranges pH 6.0-8.0 and pH 5.0-5.5 respectively. Incorporation of radiolabelled amino acids into freshly excised pieces of scalp epidermis showed that some of the polypeptides had relatively greater contents of glycine and serine than others. Radiolabelled methionine and leucine were, in contrast, incorporated more or less uniformly into all the polypeptides. After incubation with 32P-labelled orthophosphate, relatively more intense labelling by 32P was observed in the higher molecular weight bands of each family. The most basic of the isoelectric variants in each case did not take up phosphate, implying that at least some of the variation in charge was due to different degrees of phosphorylation. Polyadenylated RNA isolated from scalp epidermis was translated in an RNA-dependent reticulocyte haemolysate system followed by immunoprecipitation and electrophoresis. The polypeptides isolated by using anti-(human scalp prekeratin) immunoglobulin G had similar electrophoretic mobilities in sodium dodecyl sulphate/polyacrylamide gels to authentic prekeratin polypeptides, but had different isoelectric properties. This suggested that the products of keratin gene expression undergo post-translational modification.     

Characterization of polypeptide chains of epidermal prekeratin and reconstituted filaments

Prekeratin was isolated from bovine snout epidermis with 0.1 M citric acid/sodium citrate buffer, pH 2.6 (buffer A). Filaments, 6.0-9.0 nm wide, were produced by dialysis against low ionic strength buffer A or by dissociating prekeratin in 8 M urea solution followed by dialysis against 0.005 M Tris-HCl buffer, pH 8.0. The polypeptide composition of both prekeratin and filaments was studied by four different SDS-polyacrylamide gel electrophoresis methods. The best resolution was obtained by Laemmli's technique in which both prekeratin and filaments were separated into three major and seven distinct minor bands of polypeptides. The major ones comprise approx. 70% of total polypeptides and their estimated molecular weights are 68 000, 54 000, and 50 000. The molecular weight of minor ones is in decreasing order 65 000, 63 000, 61 000, 58 000, 47 000, 44 000 and 42 000. It is proposed that the major polypeptides form the backbone structure of epidermal filaments and the minor polypeptides play a role in its stabilization.     

The proteins of living psoriatic epidermis

Psoriatic epidermis has a rapid rate of tunrover and produces a stratum corneum with an abnormal tonofilament composition. One polypeptide chain, (M_r 70 000) is absent or greatly decreased in relative amount and two other chains, (M_r 63 000 and 55 000), which are normally modified in the living cells, persists into the stratum corneum. Increasing the turnover of normal epidermis has been shown to cause the persistence of 63 and 55 kilodalton chains in the stratum corneum but does not affect the relative amount of 70 kilodalton chain. It has, therefore, been suggested that, in psoriasis, the deficiency of the 70 kilodalton chain may occur prior to or simultaneuously with the induction of increased tissue turnover. In the present study, the polypeptide chain composition of living psoriatic epidermis has been examined. It is shown that the relative amounts of 70 kilodalton chain in psoriatic stratum corneum and involved living epidermis from the same site are not significantly different. The abnormality is therefore, already present in the living cells and it appears that, in psoriasis, the synthesis of the 70 kilodalton chain is defective. The uninvolved epidermis of psoriatics is intermediate between normal and involved psoriatic epidermis both in the ability to synthesise the 70 kilodalton chain and to modify the 63 and 55 kilodalton chains. Comparisons of amino acid compositions of proteins containing different proportions of 70 kilodalton chain suggest that it has a considerably higher content of glycine and serine than the other tonofilament chains. These studies suggest that the 70 kilodalton chain may be functionally different from the other tonofilament chains. The defect in its synthesis in psoriasis is a relatively early event and may be involved with the induction of increased tissue turnover or induced by the same abnormal conditions as the increased tissue turnover.     

Mallory bodies: Lesions of hepatocytes containing proteins of the keratin-myosin-epidermin group

Summary Mallory's alcoholic hyalin in hepatocytes was found also in other diseases and is now referred to as Mallory bodies. Data concerning their histochemical, immuno and electron microscopic properties are partly contradictory. In this study, early stages of Mallory bodies reacted strongly with configurational technics for myosins; affinity tended to decrease when material with the properties of keratohyalin and the matrix of stratum corneum was formed. Thus, many Mallory bodies contained histochemically distinct myoid and keratin-like proteins. Electron microscopists demonstrated thick and thin filaments resembling contractile systems in Mallory bodies; the failure of immunologists to visualize actomyosin may be due to the heterogeneity of these proteins. The currently popular term prekeratin has been applied to a variety of substances extracted from epidermis, hoof and hair under different conditions. The prekeratin of recent immunofluorescence studies seems to contain mainly epidermin and low molecular matrix proteins; both were studied extensively by chemists. Epithelial filaments, including tonofibrils and contractile fibrils regarded as a subgroup of myofibrils, were well known half a century ago, but were banished by electron microscopy. Observations in this study and data on epidermal actomyosin indicate that different proteins of the k-m-e-f group can indeed coexist in epithelial cells. The formation and resolution of Mallory bodies can be regarded as an example of the well known shifts of epithelial cells between secretory and keratinizing states.     

Identification of a Rapidly Labelled 350K Histidine-Rich Protein in Neonatal Mouse Epidermis

Abstract. The major histidine-rich protein (HRP) found in the stratum corneum of neonatal mouse epidermis (band 2 protein, molecular weight 27,000) is a relatively late product of epidermal differentiation and incorporates labelled amino acids in vivo only after a 6–9 h lag period. A number of putative precursor HRPs in the 70–300 K molecular weight range were initially identified using short pulse labelling times and our previously described methods for isolation of epidermis and extraction of proteins. However, when steps were taken to minimise proteolysis during preparation, a single species of approximately 350 K molecular weight was the most strongly labelled protein following a 1 h in vivo pulse of [³H]-histidine. This protein was stable in sodium dodecyl sulphate dithiothreitol at 100°C and in 4 M urea, suggesting a single covalently linked polypeptide. The kinetics of labelling and the localisation of the 350 K HRP in the lower granular layers suggest that it is a precursor of the stratum corneum HRP. The processing of the 350 K HRP to the stratum corneum species appears to involve a complex series of specific cleavage steps which give rise to a number of HRPs of intermediate molecular weight.     

Identification of a rapidly labelled 350K histidine-rich protein in neonatal mouse epidermis

The major histidine-rich protein (HRP) found in the stratum corneum of neonatal mouse epidermis (band 2 protein, molecular weight 27,000) is a relatively late product of epidermal differentiation and incorporates labelled amino acids in vivo only after a 6-9 h lag period. A number of putative precursor HRPs in the 70-300 K molecular weight range were initially identified using short pulse labeling times and our previously described methods for isolation of epidermis and extraction of proteins. However, when steps were taken to minimise proteolysis during preparation, a single species of approximately 350 K molecular weight was the most strongly labelled protein following a 1 h in vivo pulse of [3H]-histidine. This protein was stable in sodium dodecyl sulphate dithiothreitol at 100 degrees C and in 4 M urea, suggesting a single covalently linked polypeptide. The kinetics of labelling and the localisation of the 350 K HRP in the lower granular layers suggest that it is a precursor of the stratum corneum HRP. The processing of the 350 K HRP to the stratum corneum species appears to involve a complex series of specific cleavage steps which give rise to a number of HRPs of intermediate molecular weight.     

Native structure and physical properties of bovine brain kinesin and identification of the ATP-binding subunit polypeptide

Kinesin was extensively purified from bovine brain cytosol by a microtubule-binding step in the presence of 5'-adenylyl imidodiphosphate (AMP-PNP), followed by gel filtration chromatography and sucrose gradient ultracentrifugation. The products consistently contained 124,000 (124K) and 64,000 (64K) dalton polypeptides. These two polypeptides appear to represent heavy and light chains of kinesin, respectively, because they copurified on sucrose gradients to a constant and equimolar stoichiometry and bound stably to microtubules in the presence of AMP-PNP but not ATP. The mobilities of 124K and 64K in sodium dodecyl sulfate-polyacrylamide gels under reducing conditions were the same as under nonreducing conditions. A diffusion coefficient of (2.24 +/- 0.21) X 10(-7) cm2 s-1 and a sedimentation coefficient of (9.56 +/- 0.34) X 10(-13) s were determined for native kinesin by gel filtration and sucrose gradient ultracentrifugation, respectively. These values were used to calculate a native molecular weight of about 379,000 and suggest that kinesin has an axial ratio of approximately 20. Extensively purified kinesin exhibited microtubule-activated ATPase activity, and only the 124K subunit incorporated ATP in photoaffinity labeling experiments using [32P]ATP. Collectively, these data favor the interpretation that bovine brain kinesin is a highly elongated, microtubule-activated ATPase comprising two subunits each of 124,000 and 64,000 daltons, that the subunits are not linked to one another by disulfide bonds, and that the heavy chains are the ATP-binding subunits.     

Studies on the preparation of rat liver plasma membrane fractions and on their polypeptide patterns

Plasma membrane and bile canalicular membrane fractions were prepared from rat liver using NaHCO3, NaHCO3--CaCl2, and K2HPO4-KH2PO4 buffers (all at pH 7.4). The amount (expressed as milligrams protein per gram liver) of plasma membrane fraction exceeded the amount of bile canalicular membrane fraction using each of these three media; the use of NaHCO3-CaCl2 afforded a substantially higher yield of both types of membranes. The two membrane fractions exhibited complex patterns of polypeptides (greater than 30) on sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis. Several reproducible differences in polypeptide patterns were observable between the two membrane fractions; in particular, components possibly corresponding to the heavy chain of myosin and to action were prominent in the bile canalicular membrane fraction. The effects of incubation in the above three buffers and in Tris--HCl (pH 7.4) on the polypeptide patterns of both types of membrane were studied. Many polypeptides were released from each type of membrane in all of these media. Differential effects on the polypeptide patterns of either type of membrane fraction were observed among the various buffers. In terms of minimizing loss of polypeptides, in general, NaHCO3--CacCl2 appeared to be the best buffer and Tris--HCl the worst buffer. The significance of these results for the preparation and storage of liver cell plasma membrane fractions is briefly discussed.     

Mallory bodies: lesions of hepatocytes containing proteins of the keratin-myosin-epidermin group

Mallory's alcoholic hyalin in hepatocytes was found also in other diseases and is now referred to as Mallory bodies. Data concerning their histochemical, immuno and electron microscopic properties are partly contradictory. In this study, early stages of Mallory bodies reacted strongly with configurational technics for myosins; affinity tended to decrease when material with the properties of keratohyalin and the matrix of stratum corneum was formed. Thus, many Mallory bodies contained histochemically distinct myoid and keratin-like proteins. Electron microscopists demonstrated thick and thin filaments resembling contractile systems in Mallory bodies; the failure of immunologists to visualize actomyosin may be due to the heterogeneity of these proteins. The currently popular term prekeratin has been applied to a variety of substances extracted from epidermis, hoof and hair under different conditions. The prekeratin of recent immunofluorescence studies seems to contain mainly epidermin and low molecular matrix proteins; both were studied extensively by chemists. Epithelial filaments, including tonofibrils and contractile fibrils regarded as a subgroup of myofibrils, were well known half a century ago, but were banished by electron microscopy. Observations in this study and data on epidermal actomyosin indicate that different proteins of the k-m-e-f group can indeed coexist in epithelial cells. The formation and resolution of Mallory bodies can be regarded as an example of the well known shifts of epithelial cells between secretory and keratinizing states.     

The structure and subunit composition of the particulate NADH-ubiquinone reductase of bovine heart mitochondria.

Preparations of NADH-ubiquinone reductase from bovine heart mitochondria (Complex I) were shown to contain at least 16 polypeptides by gel electrophoresis in the presence of sodium dodecyl sulphate. 2. High-molecular-weight soluble NADH dehydrogenase prepared from Triton X-100 extracts of submitochondrial particles [Baugh & King (1972) Biochem. Biophys. Res. Commun. 49, 1165-1173] was similar to Complex I in its polypeptide composition. 3. Solubilization of Complex I by phospholipase A treatment and subsequent sucrose-density-gradient centrifugation did not alter the polypeptide composition. 4. Lysophosphatidylcholine treatment of Complex I caused some selective solubilization of a polypeptide of mol.wt. 33000 previosuly postulated to be the transmembrane component of Complex I in the mitochondrial membrane [Ragan (1975) in Energy Transducing Membranes: Structure, Function and Reconstitution (Bennun, Bacila & Najjar, eds.), Junk, The Hague, in the press]. 5. Chaotropic resolution of Complex I caused solubilization of polypeptides of molecular weights 75000, 53000, 29000, 26000 and 15500 and traces of others in the 10000-20000-mol.wt.range. 6. The major components of the iron-protein fraction from chaotropic resolution had molecular weights of 75000, 53000 and 29000, whereas the flavoprotein contained polypeptides of molecular weights 53000 and 26000 in a 1:1 molar ratio. 7. Iodination of Complex I by lactoperoxidase indicated that the water-soluble polypeptides released by chaotropic resolution, in particular those of the flavoprotein fraction, were largely buried in the intact Complex. 8. The polypeptides of molecular weights 75000, 53000, 42000, 39000, 33000, 29000 and 26000 were present in 1:2:1:1:1:1:1 molar proportions. The two subunits of molecular weight 53000 are probably non-identical.     

Differences in the histogenesis and keratin expression of avian extraembryonic ectoderm and endoderm recombined with dermis

The responses of the chorionic ectoderm and allantoic endoderm (from 8-day chick embryos) to dermal induction were compared through tissue recombinants grafted onto the chorioallantoic membrane. The chorionic epithelium formed the appropriate epidermis with a fully developed stratum corneum in response to both spur and scutate scale dermises. Analysis of these recombinant epidermal tissues by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that tissue-specific expression of the alpha (alpha) and beta (beta) keratin polypeptides occurred. In addition, indirect immunofluorescence studies with antisera to alpha or beta keratins showed that the beta stratum, which characterizes the epidermis of spurs and scutate scales, was formed, and the alpha keratins were distributed as in the normal epidermal tissues. In contrast, although the allantoic endoderm became stratified in association with either spur or scutate scale dermis, a stratum corneum with a beta stratum did not develop. SDS-PAGE analysis demonstrated that while the characteristic beta keratins of scutate scales and spur were not detected, most of the alpha keratins normally elaborated by these structures were present, suggesting that even without histogenesis of a stratum corneum the expression of alpha keratins of endoderm could be regulated in a tissue-specific manner by dermis. This study also demonstrated that there are differences in the abilities of the chorionic and allantoic epithelia to respond to the same dermal cues, which may reflect earlier restrictions in their developmental potentials.     

Highly effective liquid chromatography of cytochrome oxidase polypeptides

HPLC of the beef heart cytochrome oxidase subunits on TSKgel-column has been studied. It was found that the resolution of the subunits depends on the sodium dodecyl sulphate and buffer concentration. Strong interaction of subunits Va, VIc and VIIb with hydrophobic polypeptide chains was observed.     

Radiolabelling of the excretory-secretory and somatic antigens of Anisakis simplex larvae.

Anisakis simplex larvae were cultured in vitro in medium containing 35S-methionine for ten days. The medium and the larval tissues were analysed for biosynthetically labelled polypeptide by sodium dodecyl sulphate polyacrylamide gel electrophoresis and autoradiography. Immunoprecipitates with positive and negative human antisera were similarly analysed, using Staphylococcus aureus to absorb immuno-complexes. ES products of Anisakis larvae contained many polypeptides with molecular weights of less than 200 K. 180 KDa and 40 KDa polypeptides in ES products reacted with IgG in Anisakis-infected human sera. Somatic extracts also contained many polypeptides with molecular weights of less than 200 K. One of these polypeptides with a molecular weight of 130 K reacted with IgG in Anisakis-infected human sera. These polypeptides did not react with other nematode-infected human sera.