Expression profiles of melanogenesis-related genes and proteins in acquired melanocytic nevus.

UNLABELLED: We used three types of AMN to investigate the expression profiles of melanogenesis-related genes [tyrosinase, tyrosinase-related protein-1 (TRP1), dopachrome tautomerase (TRP2), Pmel-17/gp100, P-protein, and microphthalmia-associated transcription factor (MITF)], as well as tyrosinase, TRP1, Pmel-17/gp100, and MITF proteins. RESULTS: All melanogenesis-related genes examined in the junctional type were expressed in the basal epidermal layer. In the compound and intradermal types, mRNA for tyrosinase, TRP2, and MITF was expressed in all of the AMN cells. However, the expression of TRP1, P-protein, and Pmel-17/gp100 in the compound type and TRP1 in the intradermal type became weaker in accordance with the depth of the dermis layer, as compared to those levels in the basal to upper dermis layer. Although tyrosinase and Pmel-17/gp100 mRNA in the compound and intradermal types was expressed in the intraepidermal and dermal components, immunohistochemical staining showed that tyrosinase proteins were not detected in the lower dermis layer and Pmel-17/gp100 proteins were not detected in the dermis. CONCLUSIONS: Our results suggest that all nevus cells that constitute AMN tissue originate from melanocytes. Further, there may be differences in the transcription levels of melanogenesis-related genes as well as in their post-transcriptional regulation between nevus cells located in the basal epidermal to upper dermis layer and those in the lower dermis layer.

Cirri of the stalked crinoid Metacrinus rotundus: neural elements and the effect of cholinergic agonists on mechanical properties.

Sea lilies are enigmatic animals due to their scarcity and their biology is comparatively neglected. Cirri, arranged in whorls of five along the sea lily stalk, anchor and support the animal. They consist of ossicles interconnected by collagenous ligaments and by a central canal. Cirri have a well-developed nervous system but lack muscular cells. A light and electron microscopic study was performed to clarify the morphology of the nervous system of the cirri. Two cellular networks were found, one of neuron-like cells and one of cells filled with bullet-shaped organelles. Both networks ramify throughout the cirral ossicles up to the interossicle ligaments. Mechanical tests were performed to analyse the influence of cholinergic agonists on the mechanical properties of these ligaments. In the tests, the cirral ligaments softened after the application of acetylcholine, muscarinic agonists and nicotinic agonists. The reaction time to muscarinic agonists was much slower than to acetylcholine and nicotinic agonists. At low concentrations, muscarinic agonists caused active development of force. No reaction to stimuli was observed in anaesthetized cirri. The data clearly establish the existence of catch connective tissue which can change its mechanical properties under nervous control mediated via nerves with cholinergic receptors. The possible sources of the observed force production are discussed and it is concluded that active contraction of collagenous ligaments causes movement of cirri.

Glycerinated catch apparatus of sea urchin spines: the effects of cations on its mechanical properties and ultrastructure.

Sea urchin spinal ligaments (the catch apparatus) were extracted with glycerin, and electron microscopic observations comfirmed that no cell membranes remained intact after glycerination. We studied the effects of cations (Na(+), K(+), Ca(2+), Mg(2+)) on the mechanical properties of the glycerinated ligaments. Monovalent cations decreased whereas divalent cations increased the viscosity of the ligaments. The ion dependencies were similar to previous results with detergent-extracted holothurian dermis, which suggests that the echinoid ligament shares a similar mechanism for changes in mechanical properties with other catch connective tissues. This provides evidence against the hypothesis of that muscles in the catch apparatus are responsible for the changes in mechanical properties of the ligament. Fine projections cross-bridging collagen fibrils were observed in the glycerin-extracted ligaments as well as in the intact ligaments. They were found in all the ionic conditions studied.

Peptides controlling stifness of connective tissue in sea cucumbers.

We present the first evidence of a system of four bioactive peptides that affect the stiffness of sea cucumber dermis. The body wall dermis of sea cucumbers consists of catch connective tissue that is characterized by quick and drastic stiffness changes under nervous control. The peptides were isolated from the body wall, their amino acid sequences determined, and identical peptides synthesized. Two peptides, which we named holokinins, are homologous with bradykinin. We tested the effect of the peptides on the mechanical properties of sea cucumber dermis. Both of the holokinins softened the dermis, and a pentapeptide that we designated as NGIWYamide stiffened it. Both effects were reversibly suppressed by anesthesia with menthol. We called the fourth peptide stichopin; it had no direct effect on the stiffness of the dermis but suppressed action of the neurotransmitter acetylcholine reversibly. The results suggest that the peptides are neuropeptides and are part of a sophisticated system of neurotransmitters and neuromodulators that controls the connective tissue stiffness of sea cucumber dermis.

Contractile connective tissue in crinoids.

Active movements in animals are usually attributed to cellular protein engines, e.g., the actin-myosin system of muscle cells. Here we report the first evidence of an extracellular contractile connective tissue, which we have found in sea lilies and feather stars (Echinodermata, Crinoida). These marine animals have arm muscles that are antagonized, not by other muscles, but by ligaments consisting of extracellular fibrils interspersed with neuron-like cell processes. Contractile cells are lacking, yet these arm ligaments actively contracted upon stimulation. The ligaments stayed in a contracted condition even after the stimulus had stopped. The stresses generated were lower than those of typical skeletal muscles. Additional data from crinoid cirri, which lack muscles entirely, corroborate the hypothesis that the connective tissue of the ligaments is contractile.

To be Stiff or to be Soft-the Dilemma of the Echinoid Tooth Ligament. I. Morphology.

The morphology of the tooth ligament of the echinoid Eucidaris tribuloides was investigated. The tooth ligament connects the middle part of the rod-shaped tooth to the jaw. It consists of collagen and microfibrils that are synthesized by fibroblasts in the aboral growth zone of the tooth. Histochemical staining showed that the tooth ligament contains highly sulfated acid proteoglycans that seem to connect the collagen fibrils. We did not find any cell bodies in the ligament, but we observed a small number of cell processes. Dense vesicle cells and supporting cells in the jaw near the ligament send these processes among the collagen fibrils. Dense vesicle cells have connections to a newly described jaw nerve. Supporting cells possess a unique podocyte-like filtration structure that probably serves for selective pinocytosis. In the oral region, where the working part of the tooth protrudes from the jaw, collagen fibrils swell and disappear. Sometimes phagocytosis of collagen fibrils could be observed. Autoradiographic data indicate that the collagen of the tooth ligament is not subject to quick turnover. The tooth ligament resembles a catch connective tissue that can change its mechanical properties under nervous control.

To be Stiff or to be Soft-the Dilemma of the Echinoid Tooth Ligament. II. Mechanical Properties.

The teeth of sea urchins are connected to jaws by means of ligaments. Their sliding along the jaw during continuous growth requires a pliant ligament, whereas scraping on rocks for feeding requires a stiff ligament for firm support. We investigated the mechanical properties of the tooth ligament of Diadema setosum to clarify how sea urchins solve this dilemma. In creep tests a load of 30 g caused a shift of the tooth that continued until the tooth was pulled out of the jaw. The creep curve had three phases: an initial phase of high creep rate, a long phase of constant creep rate, and a final phase of accelerating creep rate. The ligaments had a shear viscosity of about 550 MPa {middot} s. Viscosity increased reversibly after stimulation with seawater containing a high concentration of potassium ions or acetylcholine. Frozen and rethawed ligaments did not show an increase of viscosity after stimulation. The data indicate that sea urchins can change the stiffness of their tooth ligaments through nervous control. We suggest that the tooth ligament is a catch connective tissue.

Cholinergic control of the mechanical properties of the catch connective tissue in the holothurian body wall.

Effects of acetylcholine (ACh), ACh-agonists and antagonists were studied on the viscosity of the dermis of the sea cucumber Holothuria leucospilota. ACh and nicotinic agonists caused an early increase in viscosity and late decrease. Muscarinic agonists produced a viscosity decrease. The viscosity increase elicited by nicotine was inhibited by tubocurarine. The viscosity decrease caused by methacholine was suppressed by atropine. The mechanical properties of this connective tissue are very likely controlled by both nicotinic and muscarinic cholinoreceptors.

Seroconversion to virus-specific pre-early nuclear antigens in infants with primary cytomegalovirus infection.

Antibodies to human cytomegalovirus (CMV)-specific antigens were determined in sera serially collected from 10 infants with primary CMV infection. Antibodies to pre-early nuclear antigens (PENA), which are detectable in human embryonic lung cells within 3 h of CMV infection by anticomplement immunofluorescence staining, developed in all the patients. However, in contrast to the early response of anti-early antigens (EA), anti-late antigens (LA), and immunoglobulin M antimembrane antigens (MA), seroconversion or the maximum antibody response to PENA was usually observed 1 or more months later. Immunoglobulin M antibody to MA became undetectable soon after recovery from illness, followed by a decrease in anti-EA, anti-PENA, and then anti-LA titers. Results indicated analogy of the clinical significance of anti-PENA in CMV infection to that of anti-Epstein-Barr nuclear antigen in infectious mononucleosis and support the idea that parallel determinations of anti-PENA and IgM anti-MA antibodies can be useful for identifying the acute or chronic phase of primary CMV infection.

Laser-induced spreading arrest of Mytilus gill cilia.

Using a "slit camera" recording technique, we have examined the effects of local laser irradiation of cilia of the gill epithelium of Mytilus edulis. The laser produces a lesion which interrupts epithelial integrity. In artificial sea water that contains high K+ or is effectively Ca++ free, metachronism of the lateral cilia continues to either side of the lesion with only minor perturbations in frequency synchronization and wave velocity, such as would be expected if metachronal wave coordination is mechanical. However, in normal sea water and other appropriate ionic conditions (i.e., where Ca++ concentration is elevated), in addition to local damage, the laser induces distinct arrest responses of the lateral cilia. Arrest is not mechanically coordinated, since cilia stop in sequence depending on stroke position as well as distance from the lesion. The velocity of arrest under standard conditions is about 3 mm/s, several orders of magnitude faster than spreading velocities associated with diffusion of materials from the injured region. Two responses can be distinguished on the basis of the kinetics of recovery of the arrested regions. These are (a) a nondecremental response that resembles spontaneous ciliary stoppage in the gills, and (b) a decremental response, where arrest nearer the stimulus point is much longer lasting. The slower recovery is often periodic, with a step size approximating lateral cell length. Arrest responses with altered kinetics also occur in laterofrontal cilia. The responses of Mytilus lateral cilia resemble the spreading ciliary arrest seen in Elliptio and arrest induced by electrical and other stimuli, and the decremental response may depend upon electrotonic spread of potential change produced at the stimulus site. If this were coupled to transient changes in Ca++ permeability of the cell membrane, a local rise in Ca++ concentration might inhibit ciliary beat at a sensitive point in the stroke cycle to produce the observed arrest.