Early Palaeozoic dentine and patterned scales in the embryonic catshark tail

Regular scale patterning, restricted to the caudalmost tail and organized into two opposing rows on each side of the tail, is observed in few chondrichthyans. These evenly spaced scales, in dorsal and ventral rows, develop in an iterative sequence from the caudal tip, either side of the notochord. They are subsequently lost as a scattered pattern of placoid scales develops on the body and fins. An identical organized pattern is observed in tail scales of Scyliorhinus canicula (catshark), where the expression of sonic hedgehog signal is restricted to the epithelium of developing scales and remains localized to the scale pocket. Regulation of iterative scale position by sonic hedgehog is deeply conserved in vertebrate phylogeny.These scales also reveal an archaic histological structure of a dentine type found in the oldest known shark scales from the Ordovician and Silurian. This combination of regulated pattern and ancient dentine occurs only in the tail, representing the primary scalation. Scattered body scales in elasmobranchs such as S. canicula originate secondarily from differently regulated development, one with typical orthodentine around a central pulp cavity. These observations emphasize the modular nature of chondrichthyan scale development and illustrate previously undetected variation as an atavism in extant chondrichthyan dentine.     

Disrupted retinal development in the embryonic belly spot and tail mutant mouse

The Belly spot and tail (Bst) semidominant mutation, mapped to mouse Chromosome 16, leads to developmental defects of the eye, skeleton, and coat pigmentation. In the eye, the mutant phenotype is characterized by the presence of retinal colobomas, a paucity of retinal ganglion cells, and axon misrouting. The severity of defects in the Bst/+ retina is variable among individuals and is often asymmetric. In order to determine the role of the Bst locus during retinal morphogenesis, we searched for the earliest observable defects in the developing eye. We examined the retinas of Bst/+ and +/+ littermates from embryonic day 9.5 (E9.5) through E13.5 and measured retinal size, cell density, cell death, mitotic index, and cell birth index. We have found that development of the Bst/+ retina is notably dilatory by as early as E10.5. The affected retinas are smaller than their wildtype counterparts, and optic fissure fusion is delayed. In the mutant, there is a marked lag in the exit of retinal cells from the mitotic cycle, even though there are no observable differences in the rate of cellular proliferation or cell death between the two groups. We hypothesize that Bst regulates retinal cell differentiation and that variability of structural defects in the mutant, such as those affecting optic fissure fusion, is a reflection of the extent of developmental delay brought about by the Bst mutation.     

Polyphosphoprotein from the adhesive pads of Mytilus edulis

Achieving a satisfactory biochemical explanation for the opportunistic underwater adhesion of marine invertebrates such as mussels and barnacles requires a detailed characterization of proteins extracted from holdfast structures produced by these organisms. Mefp-5 is an adhesive protein derived from the foot of the common mussel, Mytilus edulis, and deposited into the byssal attachment pads. Purification and primary structure of mefp-5 was determined by peptide mapping and cDNA sequencing. The protein is 74 residues long and has a mass of about 9500 Da. Mefp-5 composition shows a strong amino acid bias: aromatic amino acids, lysine, and glycine represent 65 mol % of the composition. More than a third of all the residues in the protein are posttranslationally modified by hydroxylation or phosphorylation. The conversion of tyrosine to 3, 4-dihydroxyphenyl-L-alanine (DOPA) and serine to O-phosphoserine accounts for the hydroxylation and phosphorylation, respectively. Neither modification is complete since variations in the extent of phosphorylation and hydroxylation can be detected by mass spectrometry. More than 75% of the DOPA is adjacent to basic residues, e.g., Lys-DOPA and DOPA-Lys. Phosphoserine occurs in sequences strikingly reminiscent of acidic mineral-binding motifs that appear in statherin, osteopontin, and others. This may be an adaptation for adhesion to the most common substrata for mussels, i.e., calcareous materials.     

The effect of the acidic tail on the DNA-binding properties of the HMG1,2 class of proteins: insights from tail switching and tail removal

The high-mobility group (HMG) proteins HMG1, HMG2 and HMG2a are relatively abundant vertebrate DNA-binding and bending proteins that bind with structure specificity, rather than sequence specificity, and appear to play an architectural role in the assembly of nucleoprotein complexes. They have two homologous "HMG-box" DNA-binding domains (which show about 80 % homology) connected by a short basic linker to an acidic carboxy-terminal tail that differs in length between HMG1 and 2. To gain insights into the role of the acidic tail, we examined the DNA-binding properties of HMG1, HMG2b and HMG2a from chicken erythrocytes (corresponding to HMG1, HMG2 and HMG2a in other vertebrates). HMG1, with the longest acidic tail, is less effective than HMG2a and 2b (at a given molar input ratio) in supercoiling relaxed, closed circular DNA, in inducing ligase-mediated circularisation of an 88 bp DNA fragment, and in binding to four-way DNA junctions in a gel-shift assay. Removal of the acidic tail increases the affinity of the HMG boxes for DNA and largely abolishes the differences between the three species. Switching the acidic tail of HMG1 for that of HMG2a or 2b gives hybrid proteins with essentially the same DNA-binding properties as HMG2a, 2b. The length (and possibly sequence) of the acidic tail thus appears to be the dominant factor in mediating the differences in properties between HMG1, 2a and 2b and finely tunes the rather similar DNA-binding properties of the tandem HMG boxes, presumably to fulfill different cellular roles. The tail is essential for structure-selective DNA-binding of the HMG boxes to DNA minicircles in the presence of equimolar linear DNA, and has little effect on the affinity for this already highly distorted DNA ligand, in contrast to binding to linear and four-way junction DNA.     

Isolation and characterization of microvascular endothelial cells from chicken fat pads

Summary Microvascular endothelial cells from abdominal fat pads of 6-wk-old broiler chickens were isolated to provide anin vitro system to study their physiological functions. The isolation procedure produced clumps of 10–30 cells, which attached to culture vessels in 4 h and attained confluency in 2 wk. At confluency, cells had a cobblestone appearance but were not contact inhibited and detached from the bottom of the culture vessel 2 wk after reaching confluency. The cells internalized acetylated low density lipoproteins, a characteristic of endothelial cells. This property was used to obtain pure endothelial cell cultures using the cell sorter. When cultured over Matrigel, a reconstituted matrix, the cells aligned themselves into chordlike structures and formed branching microvessels. Cells plated on type I collagen-coated culture flasks occasionally formed chordlike structures and proliferated at a faster rate than cells plated on Matrigel. Cells cultured on laminin-coated plates were slender and had long cytoplasmic extensions however, cells cultured on uncoated plastic had fibroblastic morphology. These properties are similar to those described for microvessel endothelial cells isolated from tissues of other species.     

Morphogenesis of the T4 tail and tail fibers

Remarkable progress has been made during the past ten years in elucidating the structure of the bacteriophage T4 tail by a combination of three-dimensional image reconstruction from electron micrographs and X-ray crystallography of the components. Partial and complete structures of nine out of twenty tail structural proteins have been determined by X-ray crystallography and have been fitted into the 3D-reconstituted structure of the "extended" tail. The 3D structure of the "contracted" tail was also determined and interpreted in terms of component proteins. Given the pseudo-atomic tail structures both before and after contraction, it is now possible to understand the gross conformational change of the baseplate in terms of the change in the relative positions of the subunit proteins. These studies have explained how the conformational change of the baseplate and contraction of the tail are related to the tail's host cell recognition and membrane penetration function. On the other hand, the baseplate assembly process has been recently reexamined in detail in a precise system involving recombinant proteins (unlike the earlier studies with phage mutants). These experiments showed that the sequential association of the subunits of the baseplate wedge is based on the induced-fit upon association of each subunit. It was also found that, upon association of gp53 (gene product 53), the penultimate subunit of the wedge, six of the wedge intermediates spontaneously associate to form a baseplate-like structure in the absence of the central hub. Structure determination of the rest of the subunits and intermediate complexes and the assembly of the hub still require further study.     

Blood collection from the tail of a rat

Techniques for blood collection from the rat include puncture of the heart, retro-orbital plexus, jugular vein, saphenous vein, tail blood vessels, carotid artery, abdominal aorta, and vena cava. Most techniques (except saphenous vein and tail blood vessel puncture) require anesthesia. The following discussion focuses on two methods of blood collection - ventral tail artery puncture and dorsal or lateral tail vein puncture.     

Incontinence pads: clinical performance,design and technical properties

The paper describes the functional requirements of urinary inconinence pads and reviews the results of several which seek to relate the clinical performance of pads to their design and the technical properties of their constituent materials. Pad designs covered include: simple rectangular (for use with conventional pants or marsupial pants containing a pouch); wing-folded; shaped; and all-in-one infant-style diapers. Data on the clinical and technical properties of fluff wood pulp and hydrogel absorbents, and viscose rayon, polyester, polypropylene and polyethylene coverstocks are presented. Attention is focussed on four major aspects of pad function: freedom from leakage; freedom from discomfort and skin damage; ease of application and removal; and aesthetic properties. The relationships established between clinical and technical data will be of interest to health care professionals selecting products; organizations seeking to create standards; and pad designers.     

Purification and characterization of cathepsin D-like proteinase from the tadpole tail of bullfrog, Rana catesbeiana

1. An acid aspartic proteinase in the regressing tadpole tail was purified about 800-fold with a 36% recovery. 2. The mol. wt of the enzyme was found to be 42,000 on gel filtration and 38,000 on sodium dodecyl sulfate polyacrylamide gel electrophoresis, respectively. 3. The purified enzyme had a maximum activity at pH 3.5 and an apparent Km of 0.084% with acid-denatured hemoglobin as substrate. 4. The enzyme activity was strongly inhibited by pepstatin. In addition, diazoacetylnorleucine methyl ester inactivated the enzyme in the presence of cupric ions. 5. The enzyme was identified as a cathepsin D (EC. 3.4.23.5)-like proteinase.     

Morphology and relationships of the orangutan fatty cheek pads

The present paper examines the anatomical relationships as well as possible developmental and functional relationships of the fatty cheek pad characteristic of the adult male orangutan. The research involves the dissection of 11 orangutans of both sexes in a variety of age categories. All specimens possess either a fat pad or a subcutaneous connective tissue fascial compartment in the lateral face extending superiorly from slightly above the inferior border of the mandible to the temporal region. In immature specimens as well as adult females, fat deposits within the connective tissue compartment are scarce or nonexistent, whereas pubescent male specimens or older possess accumulations of fibro-fatty tissues in this region. The extensive fat accumulations of the adult male cheek flange are related to age and sex and to modifications in related facial musculature, especially mm. platysma, zygomaticus, orbicularis oculi, and orbitotemporalis and frontalis. These muscles are clearly related to the cheek pad structures in both sexes but appear to assume a supportive role in the males. The cheek pad has no direct bony attachments, but its mass may have a significant effect on facial morphology. The development of the cheek pad is temporally variable and its function remains speculative although the presence of a fully developed flange may be related to behavioral modifications.