Optical spectroscopy of lanthanide ions in ZnO-TeO2 glasses.

Zinc tellurite glasses of compositions 19ZnO-80TeO2-1Ln2O3 with Ln = Eu, Er, Nd and Tm were prepared by melt quenching. The absorption spectra were measured and from the experimental oscillator strengths of the f-->f transitions the Judd-Ofelt parameters ohm(lambda) were obtained. The values of the ohm(lambda) parameters are in the range usually observed for oxide glasses. For Nd3+ and Er3+, luminescence spectra in the near infrared were measured and the stimulated emission cross sections sigma(p) were evaluated for some laser transitions. The high values of sigma(p), especially for Nd3+, make them possible candidates for optical applications. Fluorescence line narrowing (FLN) spectra of the Eu3+ doped glass were measured at 20 K, and the energies of the Stark components of the 7F1 and 7F2 states were obtained. A crystal field analysis was carried out assuming a C2v site symmetry. The behaviour of the crystal field ratios B22/B20 and B44/B40 agrees reasonably well with the values calculated using the geometric model proposed by Brecher and Riseberg. The crystal field strength at the Eu3+ sites appears to be very low compared to other oxide glasses.

A tissue-specific marker of Ecdysozoa.

Over the past few years, molecular studies of phylogeny have challenged the traditional view of evolutionary relationships among protostomian animal phyla. Based on analysis of 18S ribosomal RNA gene sequences, it has been suggested that some traditional groups, like the articulata and the pseudocoelomata, should be completely abandoned and that instead the protostomians should be split into two major clades: the Ecdysozoa and the Lophotrochozoa. However, this new molecular phylogeny still awaits confirmation by independent methods. In this study, we present a cytological feature that supports the new classification. The carbohydrate epitope that is recognised by antisera against the plant glycoprotein horseradish peroxidase (HRP) is known to be selectively expressed by membrane proteins on the surface of neural tissue in insects. We found that the major ecdysozoan phyla show neural expression of HRP immunoreactivity, which is completely absent in the nervous tissue of lophotrochozoans, deuterostomians, and cnidarians. This suggests that the presence of anti-HRP-reactive glycoproteins in neural tissue is an ecdysozoan autapomorphy.

The pattern of muscarinic acetylcholine receptor binding in the avian forebrain.

In autoradiographs of cryostat sections through the forebrains of domestic geese (Anser anser f. dom.) the distribution of muscarinic ACh-receptors was studied. A regionally varied receptor density is described and compared to histological subdivisions. Possible correlations of receptor pattern and functional systems are discussed.

Regional distribution of muscarinic acetylcholine receptors in the telencephalon of the pigeon (Columbia livia f. domestica).

The distribution of muscarinic ACh receptors was studied autoradiographically in cryostat sections of the pigeon telencephalon using 3H-Quinuclidinylbenzylate (QNB) as a ligand. Highest receptor density was observed in the hyperstriatum ventrale, palaeostriatum augmentatum, septum, and parts of the archistriatum In sites of known sensory input of neostriatum (field L) and ectostriatum low receptor binding was observed. Acetylcholinesterase distribution is in good agreement with the receptor picture only in the basal telencephalon. In the pallium differences in the pattern of these two components can be seen.

Neuroanatomical evidence for electroreception in lampreys.

The patterns of the anterior lateral-line afferents of Lampetra fluviatilis as revealed by transganglionic transport of horseradish peroxidase are described. The afferents form two roots in entering the rhombencephalon. Fibers of the dorsalmost root can be traced to a short dorsal fascicle which runs along the dorsal nucleus. The ventral roots form two fascicles adjacent to the nucleus intermedius. Comparison with urodeles indicates that lampreys, like urodeles and other anamniotic vertebrates are electroreceptive.

The acetylcholine system in the brain of cyclostomes with special references to the telencephalon.

The distribution of cholinergic neurons is studied in the brains of cyclostomes (Lampetra fluviatilis and Myxine glutinosa) representing an early stage of vertebrate evolution. Histochemical localization of acetylcholinesterase (AChE) is complemented by quantitative determinations of acetylcholine (ACh), cholinacetyltransferase (ChAT) and AChE. The determinations are carried out in homogenates of whole brains, the brain regions telencephalon, diencephalon, mesencephalon and medulla oblongata. The telencephalon is further subdivided and studied in more detail.The transmitter distribution found in cyclostomes is compared to data from other vertebrates. Observations on the ACh-distribution in the telencephalon are discussed with the problems of identifying telencephalic homologies.

Allometrical studies in the brain of cyclostomes.

The brain weight - body weight relation was studied in 91 specimens of the order Cyclostomata (69 Petromyzonoidea, 22 Myxinoidea) and compared to data from other vertebrates. The interspecific slope of cyclostomes differs from that of other vertebrates (a = 0.23 in petromyzonts, a = 0.41 in myxonoids). Differences observed in the relationship of brain parts to body weight in the two suborders were interpreted as due to sense organ bound specializations. In a comparative diagram of the brain weight - body weight relation in vertebrates the cyclostomes take the lowest position.

Central nervous system myelin proteins and glycoproteins in vertebrates: a phylogenetic study.

CNS myelin was isolated by a conventional method from a wide range of vertebrate classes and analyzed by SDS-PAGE for proteins (Coomassie blue) and glycoproteins (concanavalin A (Con-A)-peroxidase). Mammalian, avian and reptilian myelin shared similar protein patterns (basic protein, BP; intermediate protein, DM-20; proteolipid protein, PLP; Wolfgram protein, W). Amphibians lacked DM-20 but were characterized by specific activities of 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) higher than those of the other classes examined. The Con A-binding profiles were similar in the high molecular weight (HMW) regions of the classes listed above, while the typical myelin proteins in the low molecular weight (LMW) regions were devoid of Con A-binding properties. In teleost myelin a putative BP band ran well ahead of rat small basic protein (SBP), whereas the region corresponding to rat PLP was covered by several closely spaced bands, most of which bound Con A. In elasmobranch myelin, apart from bands corresponding to BP, Con A-binding glycoproteins were detected migrating in the region of rat DM-20 and PLP as well as with mammalian PNS P0 protein. Cyclostomates yielded only very small amounts of material in the myelin preparation and displayed undifferentiated Coomassie blue- and Con A-binding in the HMW region, while typical LMW myelin proteins were absent. These results demonstrate that CNS myelin from bony and cartilaginous fishes is characterized by containing several major Con A-binding proteins of low molecular weight. This is in striking contrast to myelin from phylogenetically higher classes.

The distribution of acetylcholinesterase in the cyclostome brain. II. Myxine glutinosa.

In the brain of the hagfish Myxine glutinosa the distribution of acetylcholinesterase has been studied in serial cryostat sections. High activity was found in the motor column of the brain stem, in the pars ventralis thalami and in the primordium hippocampi. In the hemispheres and the olfactory bulb the ACHE-content is low.