Biomedical subjects

R Huber

Publications and source records attributed to R Huber.

At least 505 records · Page 28Linked to original sources

PubMed1991

Short-term effects of oral enoximone on hemodynamics, exercise capacity, anaerobic threshold, and arrhythmias in congestive heart failure.

Enoximone, a phosphodiesterase-inhibitor, is a potent inotropic vasodilator agent that causes a marked improvement in hemodynamics in patients with congestive heart failure. The acute effects of oral enoximone on rest and exercise hemodynamics, ejection fraction, aerobic metabolism, exercise capacity, and arrhythmias were studied in 11 patients with moderate to moderately severe dilative cardiomyopathy after 8 days of enoximone (100 mg tid) in addition to baseline therapy (diuretics and digitalis). The cardiac index increased from 2.44 +/- 0.45 to 2.72 +/- 0.50 l/min/m2 (p less than 0.01) at rest and from 4.00 +/- 0.96 to 4.75 +/- 0.95 l/min/m2 (p less than 0.005) during exercise. Pulmonary wedge pressure decreased from 16.8 +/- 7.3 to 12.5 +/- 6.5 mmHg (p less than 0.005) at rest and from 28.2 +/- 8.0 to 24.5 +/- 10.3 mmHg (p less than 0.05) during exercise. Systemic vascular resistance decreased from 1608 +/- 243 to 1495 +/- 300 dynes*sec*cm-5 (p less than 0.05) at rest and from 1152 +/- 155 to 1027 +/- 236 dynes*sec*cm-5 (ns) during exercise. The anaerobic threshold, which was recorded simultaneously, increased from 13.2 +/- 2.7 to 15.5 +/- 2.5 ml/kg/min VO2 (p less than 0.02). The radionuclide ventriculography ejection fraction improved from 21.7 +/- 5.0 to 28.1 +/- 9.1% (p less than 0.01) during exercise; the changes at rest were not significant (20.8 +/- 6.2 vs 25.8 +/- 8.4%). Exercise tolerance showed an increase of 16% (492 +/- 133 to 573 +/- 135 sec, p less than 0.005). The resting heart rate remained unchanged (81.8 +/- 13.4 vs 81.8 +/- 11.9). Interestingly, 24-h Holter monitoring revealed more or new repetitive arrhythmias in 9/11 patients.

Adult↗

PubMed1991

Structure of soluble and membrane-bound human annexin V.

Annexins are a family of water-soluble proteins that bind to membranes in a calcium-dependent manner. Some members have been shown to exhibit voltage-dependent calcium channel activity, a property characteristic of integral membrane proteins. The structures of human annexin V in crystals obtained from aqueous solution and in two-dimensional crystals when bound to phospholipid layers have been determined by X-ray and electron crystallography, respectively. They are compared here. Both structures show close correspondence, suggesting that annexins attach to phospholipid membranes without substantial structural change. These observations, together with biochemical data, lead to the conclusion that annexin V interacts with phospholipid membranes with its convex face. We propose that binding is mediated by direct interaction between the phosphoryl headgroups and the calcium bound to polypeptide loops protruding from the convex face. The membrane area covered by annexin may thus become disordered and permeable allowing calcium flux through the membrane and the central channel-like structure found in annexin molecules.

Amino Acid Sequence↗

PubMed1991

Crystal structure of cleaved human alpha 1-antichymotrypsin at 2.7 A resolution and its comparison with other serpins.

The crystal structure of proteolytically modified human alpha 1-antichymotrypsin (ACT), a member of the serpin superfamily, has been solved by Paterson search techniques and refined to an R-factor of 18.0% at 2.7 A resolution with mean deviations from standard bond lengths and angles of 0.013 A and 3.1 degrees, respectively. The final model consists of 374 amino acid residues, 126 solvent molecules and five sugar residues. Asn70 could be identified unambiguously as a glycosylation site and Asn104 is probably also glycosylated. The structure of cleaved ACT is compared with cleaved alpha 1-antitrypsin (alpha 1 PI) and with plakalbumin, which are prototypical models for cleaved and intact serpins, respectively. Cleaved ACT is very similar to cleaved alpha 1 PI; in particular, it has strand s4A, which is liberated by proteolysis, inserted as the middle strand in beta-sheet A. ACT and alpha 1 PI differ locally only at sites of insertions, except at the segment s3C-turn-s4C, which is displaced by several angström units. This region of ACT is involved in DNA binding.

Amino Acid Sequence↗

PubMed1991

Class pi glutathione S-transferase from pig lung. Purification, biochemical characterization, primary structure and crystallization.

A cytosolic glutathione S-transferase from pig lung was purified 210-fold to apparent homogeneity. The enzyme was classified as a class pi isoenzyme on the basis of its physical and chemical properties. It is homodimeric with a subunit Mr of 23,500, has a pI of 7.2, and shows a high specific activity towards ethacrynic acid. The glutathione analogues, S-hexylglutathione and glutathione sulfonate, were strong reversible inhibitors. The enzyme's primary structure, established entirely by protein chemical methods, consists of 203 amino acids and is highly similar (82-84% residue identity) to the rat and human class pi isoenzymes. Furthermore, there was no evidence of microheterogeneity or post-translational modifications. Each subunit contains a highly reactive cysteine residue, the modification of which leads to enzyme inactivation. None of the cysteine residues in the pig enzyme appear to form intramolecular disulfide bonds. Singel crystals of the glutathione-S-transferase-glutathione-sulfonate complex were obtained by the hanging-drop method of vapour diffusion from poly(ethylene glycol) 4000 solutions. The crystals belong to the orthorhombic space group P212121 with unit cell dimensions of a = 10.125 nm, b = 8.253 nm and c = 5.428 nm and diffract to better than 0.22 nm.

Amino Acid Sequence↗

PubMed1991

X-ray crystal structure of the two site-specific mutants His35Gln and His35Leu of azurin from Pseudomonas aeruginosa.

The three-dimensional structures of two site-specific mutants of the blue copper protein azurin from Pseudomonas aeruginosa have been solved by a combination of isomorphous replacement and Patterson search techniques, and refined by energy-restrained least-squares methods. The mutations introduced by recombinant DNA techniques involve residue His35, which was exchanged for glutamine and leucine, to probe for its suggested role in electron transfer. The two mutants, His35Gln (H35Q) and His35Leu (H35L), crystallize non-isomorphously in the orthorhombic space group P2(1)2(1)2(1) with unit cell dimensions of a = 109.74 A, b = 99.15 A, c = 47.82 A for H35Q, a = 57.82 A, b = 81.06 A, c = 110.03 A for H35L. In each crystal form, there are four molecules in the asymmetric unit. They are arranged as a dimer of dimers in the H35Q case and are distorted from ideal C2 symmetry in H35L. The final crystallographic R-value is 16.3% for 20.747 reflections to a resolution of 2.1 A for H35Q and 17.0% for 32,548 reflections to 1.9 A for H35L. The crystal structures reported here represent the first crystallographically refined structures for azurin from P. aeruginosa. The structure is very similar to that of azurin from Alcaligenes denitrificans. The copper atom is located about 7 A below a hydrophobic surface region and is ligated by five donor groups in a distorted trigonal bipyramidal fashion. The implications for electron transfer properties of the protein are discussed in terms of the mutation site and the packing of the molecules within the tetramer.

Amino Acid Sequence↗

PubMed1991

Isolation, crystallization, crystal structure analysis and refinement of constitutive C-phycocyanin from the chromatically adapting cyanobacterium Fremyella diplosiphon at 1.66 A resolution.

Constitutive phycocyanin from cyanobacterium Fremyella diplosiphon (Calothrix sp. PCC 7601) grown in green light, has been isolated and crystallized. The crystals belong to the space group R3 with cell constants a = b = 180.26 A, c = 61.24 A, alpha = beta = 90 degrees, gamma = 120 degrees. The crystal structure has been determined by Patterson search techniques using the molecular model of C-phycocyanin from the cyanobacterium Agmenellum quadruplicatum. The asymmetric unit of the crystal cell consists of two (alpha beta)-monomers related by a local dyad. Three asymmetric units are arranged around a crystallographic triad and form an (alpha beta)6-hexamer, the functional unit in the native antenna rod. The initial structure has been refined in a cyclic manner by energy-restrained crystallographic refinement and modelling until the conventional crystallographic R-factor converged at 18.1% with data to a resolution of 1.66 A. The molecular structure resembles closely the C-phycocyanins of Mastigocladus laminosus and A. quadruplicatum. The conformation and configuration of the alpha-84 and beta-84 chromophores is very similar to the corresponding chromophores in the trimeric C-phycocyanin of M. laminosus, whereas the beta-155 chromophore differs in configuration with C(4)-Z, C(10)-Z and C(15)-Z compared to C(4)-Z, C(10)-Z, C(15)-Z,E. The stereochemistry of the beta-155 chiral centres is C(2)-RC(3)-R and C(31)-S, respectively, whereas alpha-84 and beta-84 have C(2)-RC(3)-R and C(31)-R. The amino acid sequences of constitutive and inducible phycocyanin differ mainly in residues located on the surface of the beta-subunits that mediate the inter-hexameric contacts.

Amino Acid Sequence↗

PubMed1991

Conformational analysis of a IgG1 hinge peptide derivative in solution determined by NMR spectroscopy and refined by restrained molecular dynamics simulations.

The hinge region links the antigen binding Fab part to the constant Fc domain in immunoglobulins. For the hinge peptide derivative [AcThr(OtBu)-Cys-Pro-Pro-Cys-Pro-Ala-ProNH2]2 the assignment of the 1H and 13C resonances was achieved by two-dimensional nmr techniques: total correlation spectroscopy (TOCSY), nuclear Overhauser enhancement spectroscopy (NOESY), rotating frame nuclear Overhauser enhancement spectroscopy (ROESY), heteronuclear multiple quantum coherence (HMQC) transfer, and a HSQC (modified Overbodenhausen experiment) with high resolution in F1, which was several times folded in F1 but still phase correctable. Conformational relevant parameters (78 nuclear Overhauser effect distance restraints, 3JHH for prochiral assignments, temperature gradients) were determined by nmr and served as input data for molecular dynamics (MD) structure refinement. A simulated model compound corresponding to the [Cys-Pro-Pro-Cys]2 core elongated by the peptide chains in the Fab and Fc direction served as a starting structure for the final MD run. The conformation calculated in in vacuo does not agree with the C2 symmetry required from nmr data, but the structure obtained by a water simulation fulfills the requirement. Here the core of the hinge peptide derivative adopts a polyproline II double helix as in the x-ray structure of IgG1. Hence, segments responsible for the internal flexibility are located outside the core as confirmed by the flexibility of the solvent exposed C termini.

Amino Acid Sequence↗

PubMed1991

The three-dimensional structure of class pi glutathione S-transferase in complex with glutathione sulfonate at 2.3 A resolution.

The three-dimensional structure of class pi glutathione S-transferase from pig lung, a homodimeric enzyme, has been solved by multiple isomorphous replacement at 3 A resolution and preliminarily refined at 2.3 A resolution (R = 0.24). Each subunit (207 residues) is folded into two domains of different structure. Domain I (residues 1-74) consists of a central four-stranded beta-sheet flanked on one side by two alpha-helices and on the other side, facing the solvent, by a bent, irregular helix structure. The topological pattern resembles the bacteriophage T4 thioredoxin fold, in spite of their dissimilar sequences. Domain II (residues 81-207) contains five alpha-helices. The dimeric molecule is globular with dimensions of about 55 A x 52 A x 45 A. Between the subunits and along the local diad, is a large cavity which could possibly be involved in the transport of nonsubstrate ligands. The binding site of the competitive inhibitor, glutathione sulfonate, is located on domain I, and is part of a cleft formed between intrasubunit domains. Glutathione sulfonate is bound in an extended conformation through multiple interactions. Only three contact residues, namely Tyr7, Gln62 and Asp96 are conserved within the family of cytosolic glutathione S-transferases. The exact location of the binding site(s) of the electrophilic substrate is not clear. Catalytic models are discussed on the basis of the molecular structure.

Amino Acid Sequence↗

PubMed1991

The refined 2.15 A X-ray crystal structure of human liver cathepsin B: the structural basis for its specificity.

From the lysosomal cysteine proteinase cathepsin B, isolated from human liver in its two-chain form, monoclinic crystals were obtained which contain two molecules per asymmetric unit. The molecular structure was solved by a combination of Patterson search and heavy atom replacement methods (simultaneously with rat cathepsin B) and refined to a crystallographic R value of 0.164 using X-ray data to 2.15 A resolution. The overall folding pattern of cathepsin B and the arrangement of the active site residues are similar to the related cysteine proteinases papain, actinidin and calotropin DI. 166 alpha-carbon atoms out of 248 defined cathepsin B residues are topologically equivalent (with an r.m.s. deviation of 1.04 A) with alpha-carbon atoms of papain. However, several large insertion loops are accommodated on the molecular surface and modify its properties. The disulphide connectivities recently determined for bovine cathepsin B by chemical means were shown to be correct. Some of the primed subsites are occluded by a novel insertion loop, which seems to favour binding of peptide substrates with two residues carboxy-terminal to the scissile peptide bond; two histidine residues (His110 and His111) in this "occluding loop' provide positively charged anchors for the C-terminal carboxylate group of such polypeptide substrates. These structural features explain the well-known dipeptidyl carboxypeptidase activity of cathepsin B. The other subsites adjacent to the reactive site Cys29 are relatively similar to papain; Glu245 in the S2 subsite favours basic P2-side chains. The above mentioned histidine residues, but also the buried Glu171 might represent the group with a pKa of approximately 5.5 near the active site, which governs endo- and exopeptidase activity. The "occluding loop' does not allow cystatin-like protein inhibitors to bind to cathepsin B as they do to papain, consistent with the reduced affinity of these protein inhibitors for cathepsin B compared with the related plant enzymes.

Amino Acid Sequence↗

PubMed1991

Three-dimensional structure of porcine procarboxypeptidase B: a structural basis of its inactivity.

Procarboxypeptidase B is converted to enzymatically active carboxypeptidase B by limited proteolysis catalysed by trypsin, removing the long N-terminal activation segment of 95 amino acids. The three-dimensional crystal structure of procarboxypeptidase B from porcine pancreas has been determined at 2.3 A resolution and refined to a crystallographic R-factor of 0.169. The functional determinants of its enzymatic inactivity and of its activation by limited proteolysis have thus been unveiled. The activation segment folds in a globular region with an open sandwich antiparallel-alpha antiparallel-beta topology and in a C terminal alpha-helix which connects it to the enzyme moiety. The globular region (A7-A82) shields the preformed active site, and establishes specific interactions with residues important for substrate recognition. AspA41 forms a salt bridge with Arg145, which in active carboxypeptidase binds the C-terminal carboxyl group of substrate molecules. The connecting region occupies the putative extended substrate binding site. The scissile peptide bond cleaved by trypsin during activation is very exposed. Its cleavage leads to the release of the activation segment and to exposure of the substrate binding site. An open-sandwich folding has been observed in a number of other proteins and protein domains. One of them is the C-terminal fragment of L7/L12, a ribosomal protein from Escherichia coli that displays a topology similar to the activation domain of procarboxypeptidase.

Amino Acid Sequence↗

PubMed1991

Methyl-coenzyme M reductase and other enzymes involved in methanogenesis from CO2 and H2 in the extreme thermophile Methanopyrus kandleri.

Methanopyrus kandleri belongs to a novel group of abyssal methanogenic archaebacteria that can grow at 110 degrees C on H2 and CO2 and that shows no close phylogenetic relationship to any methanogen known so far. Methyl-coenzyme M reductase, the enzyme catalyzing the methane forming step in the energy metabolism of methanogens, was purified from this hyperthermophile. The yellow protein with an absorption maximum at 425 nm was found to be similar to the methyl-coenzyme M reductase from other methanogenic bacteria in that it was composed each of two alpha-, beta- and gamma-subunits and that it contained the nickel porphinoid coenzyme F430 as prosthetic group. The purified reductase was inactive. The N-terminal amino acid sequence of the gamma-subunit was determined. A comparison with the N-terminal sequences of the gamma-subunit of methyl-coenzyme M reductases from other methanogenic bacteria revealed a high degree of similarity. Besides methyl-coenzyme M reductase cell extracts of M. kandleri were shown to contain the following enzyme activities involved in methanogenesis from CO2 (apparent Vmax at 65 degrees C): formylmethanofuran dehydrogenase, 0.3 U/mg protein; formyl-methanofuran:tetrahydro-methanopterin formyltransferase, 13 U/mg; N5,N10-methylenetetrahydromethanopterin cyclohydrolase, 14U/mg; N5,N10-methenyltetrahydromethanopterin dehydrogenase (H2-forming), 33 U/mg; N5,N10-methylenetetrahydromethanopterin reductase (coenzyme F420 dependent), 4 U/mg; heterodisulfide reductase, 2 U/mg; coenzyme F420-reducing hydrogenase, 0.01 U/mg; and methylviologen-reducing hydrogenase, 2.5 U/mg. Apparent Km values for these enzymes and the effect of salts on their activities were determined. The coenzyme F420 present in M. kandleri was identified as coenzyme F420-2 with 2-gamma-glutamyl residues.

Amino Acid Sequence↗

PubMed1991

Vasculitic mononeuritis multiplex in patient with Lyme disease.

Lyme borreliosis is an infectious disease caused by the spirochete Borrelia burgdorferi. Neurological complications are frequently reported but the pathogenesis remains largely unknown. We report on a patient with positive borrelia antibodies at ELISA and immunoblotting and with histological and immunofluorescence study of peripheral nerve biopsy consistent with vasculitic neuropathy.

Antibodies, Bacterial↗

PubMed1991

[Local muscle flap in soft tissue reconstruction following fracture and osteitis of the lower limb].

17 local muscle flaps were used to cover soft tissue defects in 13 open fractures (1 degree to 4 degrees) of the lower limb and in four patients with chronic ostitis associated with instable scar forming. The Musculus soleus was used in 16 cases exclusively or in combination with the Musculus gastrocnemius (three times), Musculus hallucis longus (one time) or Musculus tibialis anterior (one time). In one case the Musculus flexor digitorum was used. In 13 of 17 cases the local muscle flap was curing the soft tissue defect and contributed to the salvage of the limb.

Adolescent↗

PubMed1991

Role of electrostatic interaction in the stability of the hexamer of constitutive phycocyanin from Fremyella diplosiphon.

The role of electrostatic interactions between the charges carried by the titratable groups in the different aggregates of constitutive phycocyanin from Fremyella diplosiphon has been studied by using a simple theoretical approach based on the modified Tanford-Kirkwood model. The electrostatic potential has also been calculated by means of a numerical solution of the linearized Poisson-Boltzmann equations using the finite-differences technique. The pH dependence of the electrostatic contribution to free energy suggests an electrostatic stabilization of the alpha- and beta-subunits as well as of the (alpha beta)-monomer over a broad pH interval. The charge distributions in the individual alpha- and beta-subunits produce electrostatic complementarity and promote the assembly of the subunits to the (alpha beta)-monomer, as well as of the monomers to the larger trimeric and hexameric aggregates. Trimer-trimer electrostatic interactions exhibit strong pH dependence, predicting an association/dissociation equilibrium with a midpoint at pH 6. The electrostatic trimer-trimer interactions correspond to the steric fit, suggesting that electrostatic interactions may initially help to orient the trimers during aggregation. The distribution of the electrostatic potential of the monomers and of the higher aggregates suggests that it plays an important role also in phycocyanin-linker protein binding.

Computer Simulation↗

PubMed1991

Plasma growth hormone (GH)-releasing hormone levels in patients with lung carcinoma.

OBJECTIVE: The aim was to investigate the serum levels of growth hormone releasing hormone and GH in patients with lung carcinoma. DESIGN After an overnight fast a plasma sample was collected for determination of growth hormone releasing hormone and GH. PATIENTS: The investigation was performed in 28 patients with non small cell lung carcinoma, in 44 patients with small cell lung carcinoma, and 10 patients with non malignant lung disease. A group of 37 normal subjects served as control. MEASUREMENTS: Growth hormone releasing hormone and GH were determined by radioimmunoassay. RESULTS: Patients with small cell lung carcinoma showed higher plasma growth hormone releasing hormone levels (49 +/- 9.4 ng/l) than control subjects (16.3 +/- 2.1 ng/l; P less than 0.05), patients with non small cell lung carcinoma (23.9 +/- 8.8 ng/l; P less than 0.05), and patients with non malignant lung disease (12.7 +/- 5.5; P less than 0.05). Basal GH level was lower than 5 micrograms/l in all patients except five patients with small cell lung carcinoma and one patient with non small cell lung carcinoma. CONCLUSIONS: The higher plasma growth hormone releasing hormone levels in patients with small cell lung carcinoma compared to normal controls and patients with non small cell lung carcinoma and patients with non malignant lung disease, confirm the frequent neuroendocrine activity of this particular tumour.

Adult↗

PubMed1991

Eltenac, a new anti-inflammatory and analgesic drug for horses: clinical aspects.

Two controlled studies to determine efficacy in the horse were performed with eltenac, a new injectable, non-steroidal anti-inflammatory drug (NSAID). Clinical trials were carried out with a dose rate of 1 mg/kg body weight in a randomized, placebo-controlled, double-blind design to assess therapeutic efficacy in acute inflammatory disorders and in animals with orthopaedic conditions. In a preliminary pharmacokinetic investigation in six horses mean elimination half-life was 1.7 h after i.v. administration. In the first clinical study, analgesic activity on pain-related lameness was determined in a total of 64 horses. Pain was assessed using a rating scale. Compared with the placebo treatment, eltenac produced significant pain relief after a single i.v. injection for a period of 24 h. In the second trial the anti-oedematous effect was determined in post-operative wound swelling following castration in two groups of 10 colts. After surgery, the horses received either an injection of 1 mg/kg eltenac or a placebo injection on three consecutive days. Swelling was assessed by measuring the diameter of the external preputial fold using two methods: callipers and a rating scale of 0 to 3. Additionally, photographs were taken on days 1, 2 and 4. Compared with the placebo treatment, eltenac inhibited pain and swelling significantly. The effect was maintained for up to 48 h after the last injection.

Aniline Compounds↗

PubMed1991

The cell envelope of the hyperthermophilic archaebacterium Pyrobaculum organotrphum consists of two regularly arrayed protein layers: three-dimensional structure of the outer layer.

The cell envelope of the hyperthermophilic sulphur-reducing archaebacterium Pyrobaculum organotrophum H10 was found to be composed of two distinct hexagonally arranged crystalline protein arrays. Electron microscopic analysis of freeze-etched cells and isolated envelopes in conjunction with image processing showed that the inner layer (lattice centre-to-centre spacing 27.9 nm) is essentially identical to the protein array of Pyrobaculum islandicum GEO3, a complex, rigid structure implicated in the maintenance of cell shape. The outer layer has clear p6 symmetry and a lattice spacing of 20.6 nm. Its three-dimensional structure was reconstructed from a negative stain tilt series of an intact double-layered envelope using Fourier filtration to separate the desired information from the other lattices present. The outer layer is a unique, porous network of blocklike dimers disposed around six-fold axes, and exhibits minimal asymmetry between its inner and outer faces. It appears to be rather loosely associated with the outer surface of the inner layer. In most H10 envelopes, the inner layer is orientated with one base vector exactly perpendicular to the long axis of the cell, so that the cylindrical portion is composed of a series of parallel cell-girdling hoops of hexameric morphological units. All the other known Pyrobaculum strains were found to have a GEO3-type envelope structure, consisting of a single rigid protein array and a fibrous capsule. Although H10 does not possess a capsule, fibrils appear to be sandwiched between the two protein layers.

Archaea↗

PubMed1991

Differential expression and localization of brain-type and mitochondrial creatine kinase isoenzymes during development of the chicken retina: Mi-CK as a marker for differentiation of photoreceptor cells.

The expression and the cellular- as well as subcellular-distribution of brain-type B-CK and mitochondrial Mi-CK during development of the chicken retina was studied by immunoblotting, immunofluorescence and immunogold methods. B-CK expression and accumulation in retina was high from early stages of embryonic development on, decreased slightly around hatching and remained high again during adulthood. At early stages of development (days 2-5), B-CK was more or less evenly distributed over the entire retina with the exception of ganglion cells, which were stained more strongly for B-CK than other retinal precursor cells. Then, at around day 10, the beginning of stratified immunostaining by anti-B-CK antibody was noted concomitant with progressing differentiation. Finally, a dramatic increase in staining of the differentiating photoreceptor cells was seen before hatching (day 18) with weaker staining of other cell types. At hatching, as in the adult state, most of the B-CK was localized within rods and cones. Thus, during retinal development marked changes in the immunostaining pattern for B-CK were evident. By contrast, Mi-CK expression was low during development in ovo and rose just before hatching with a predominant accumulation of this isoenzyme within the ellipsoid portion of the inner photoreceptor cell segments. Mi-CK accumulation in the retina coincided with functional maturation of photoreceptors and therefore represents a good marker for terminal differentiation of these cells. B-CK, present from early stages of retina development, seems to be relevant for the energetics of retinal cell proliferation, migration and differentiation, whereas the simultaneous expression of both B- and Mi-CK around the time of hatching indicates a coordinated function of the two CK isoforms as constituents of a PCr-circuit involved in the energetics of vision, which, in autophagous birds, has to be operational at this point in time.

Animals↗