Efferent connections from the brain to the frontal organ in Rana temporaria demonstrated by labeling with horseradish peroxidase

After injection of horseradish peroxidase into the frontal organ of Rana temporaria, labeled perikarya were found in the medial part of the amygdala, the preoptic area, the nucleus rotundus, the pretectal area, and the lateral parts of the midbrain central griseum.     

Darstellung selektiv blockierter 2-azido-2-desoxy-D-gluco- und -D-galactopyranosylhalogenide: reaktivität und 13C-NMR-spektren

The synthesis of several 2-azido-2-deoxy-D-gluco- and -D-galactopyranosyl halides is described. With tetraethylammonium chloride, α-pyranosyl bromides react to give β-pyranosyl chlorides. This provides a facile method for obtaining selectively blocked halides for the synthesis of α-linked, amino sugar of oligosaccharides. The inversion reaction at the anomeric centre is shown to be of second order, corresponding to an SN2 mechanism. The rates of the inversion reactions were correlated to the ¹³C-n.m.r. data of C-1 of α-bromides. Within the gluco series, the ¹³C-n.m.r. shift of C-1 proves to be proportional to the natural logarithm of the rate constant. An analogous correlation in the galacto series could not be observed.     

Ganglioside alterations in YAC-1 cells cultivated in serum-supplemented and serum-free growth medium

Gangliosides of the G_M1b-pathway (G_M1b and GalNAc-G_M1b) have been found to be highly expressed by the mouse T lymphoma YAC-1 grown in serum-supplemented medium, whereas G_M2 and G_M1 (G_M1a-pathway) occurred only in low amounts [Müthing, J., Peter-Katalini, J., Hanisch, F.-G., Neumann, U. (1991)Glycoconjugate J 8:414–23]. Considerable differences in the ganglioside composition of YAC-1 cells grown in serum-supplemented and in well defined serum-free medium were observed. After transfer of the cells from serum-supplemented medium (RPMI 1640 with 10% fetal calf serum) to serum-free medium (RPMI 1640 with well defined supplements), G_M1b and GalNAc-G_M1b decreased and only low amounts of these gangliosides could be detected in serum-free growing cells. The expression of G_M1a was also diminished but not as strongly as that of G_M1b and GalNAc-G_M1b. These growth medium mediated ganglioside alterations were reversible, and the original ganglioside expression was achieved by readaptation of serum-free growing cells to the initial serum-supplemented medium. On the other hand, a new ganglioside, supposed to represent GalNAc-G_D1a and not expressed by serum-supplemented growing cells, was induced during serum-free cultivation, and increased strongly after readaptation. These observations reveal that the ganglioside composition ofin vitro cultivated cells can be modified by the extracellular environment due to different supplementation of the basal growth medium. Abbreviations: BSA, bovine serum albumin GSL(s), glycosphingolipid(s); HPTLC, high-performance thin-layer chromatography; LDL, low density lipoprotein; NeuAc,N-acetylneuraminic acid; NeuGc,N-glycoloylneuraminic acid. The designation of the following glycosphingolipids follows IUPAC-IUB recommendations. GgOse₃Cer or gangliotriaosylceramide, GalNAc1-4Gal1-4GlcCer; GgOse₄Cer or gangliotetraosylceramide, Gal1-3GalNAc1-4Gla1-4GlcCer; GgOse₅Cer or gangliopentaosylceramide, GalNAc1-4Gal1-3GalNAc1-4Gal1-4GlcCer; GgOse₆Cer or gangliohexaosylceramide, Gal1-3GalNAc1-4Gal1-3GalNAc1-4Gal1-4GlcCer or GgOse₆Cer; II³NeuAc-GgOse₃Cer or G_M2; II³NeuAc-GgOse₄Cer or G_M1 or G_M1a; IV³NeuAc-GgOse₄Cer or G_M1b; IV³NeuAc-GgOse₅Cer or GalNAc-G_M1b; IV³NeuAc-GgOse₆Cer or Gal-GalNAc-G_M1b; IV³NeuAc, II³NeuAc-GgOse₄Cer or G_D1a; II³(NeuAc)₂-GgOse₄Cer or G_D1b; IV³NeuAc, III⁶NeuAc-GgOse₄Cer or G_D1a; IV³NeuAc, II³NeuAc-GgOse₅Cer or GalNAc-G_D1a. Enzymes: Vibrio cholerae andArthrobacter ureafaciens neuraminidase (EC 3.2.1.18).     

The impact of lead on the assimilation efficiency of laboratory-held Diplopoda (Arthropoda) preconditioned in different environmental situations

Summary In five diplopod species from three families collected from locations with different soil metal contents, the following parameters were examined: the litter mass (and energy) ingested per day, the mass (and energy) assimilation rates, and the litter mass (and energy) assimilated per day, when the diplopods were fed (1) uncontaminated and (2) artificially lead-enriched leaf litter. These parameters were compared between species and between animals from different sites. The mass and energy assimilation efficiencies depend on (1) the size of the species and (2) the collection site of the animals. Relative mass (and in three of the species examined also energy) assimilation was highest in those animals collected from the less contaminated sites. With artificial diets, specimens from a site with soil contaminated by heavy metals showed greater assimilation of both mass and energy than originally unaffected specimens. One species (Glomeris conspersa) was able to compensate for the low assimilation rate by increased consumption, and thus guarantee a sufficient energy supply. One of the other species (Polydesmus denticulatus), however, did not show this compensation. Animals of this species from less contaminated sites showed a very low absolute energy assimilation rate and high mortality under lead treatment.     

Transformation of Dibenzo-p-Dioxin by Pseudomonas sp. Strain HH69

Dibenzo-p-dioxin was oxidatively cleaved by the dibenzofuran-degrading bacterium Pseudomonas sp. strain HH69 to produce minor amounts of 1-hydroxydibenzo-p-dioxin and catechol, while a 2-phenoxy derivative of muconic acid was formed as the major product. Upon acidic methylation, the latter yielded the dimethylester of cis, trans-2-(2-hydroxyphenoxy)-muconic acid.     

Extravascular circulation in the pituitary of Mugil cephalus (Teleostei)

Summary Extravascular circulation in the pituitary of Mugil cephalus was investigated by injecting live fish with horseradish peroxidase and studying the distribution of the enzyme in the gland. The principal components of the extravascular circulatory system are the pericapillary spaces, and, arising from them, the interlobular and circumhypophyseal spaces. Extensions of these spaces penetrate the glandular parenchyma of the pars distalis, where they merge with pericellular spaces. In the neurohypophysis, pericapillary spaces are connected to the periaxonal spaces.Capillaries penetrating from the proximal neurohypophysis into the pars distalis are accompanied by neurosecretory axons. These axons form a mass of tissue which is limited near the capillaries by the pericapillary spaces and near the adenohypophysis by the interlobular spaces. Toward the interior of the adenohypophysis the amount of nervous tissue accompanying the capillaries progressively diminishes, thus reducing the distance between pericapillary and interlobular spaces. Within the pars distalis, the neurosecretory axons accompanying the capillaries are sparse, and the secretory and stellate cells are mostly located directly adjacent to the pericapillary spaces. In the neuro-intermediate lobe, interlobular spaces outline the neuro-adenohypophyseal boundary.The relationship between extravascular spaces and hormone-secreting cells varies in the different regions of the adenohypophysis depending upon the type of neurosecretory innervation in the respective region. In the regions of prolactin and gonadotropin cells, where neurosecretory axons are in direct contact with the secretory cells, the hormone-secreting and stellate cells are adjacent to the pericapillary spaces. In the regions of ACTH and STH cells, secretory and stellate cells are found adjacent to the interlobular spaces, which are interposed between the cells and the neurosecretory axons.Abbreviations AH adenohypophysis - CH circumhypophyseal - DNH distal neurohypophysis - HRP horseradish peroxidase - NH neurohypophysis - NS neurosecretory - PD pars distalis - PI pars intermedia - PPD proximal pars distalis - RNH rostral neurohypophysis - RPD rostral pars distalis This research was supported by a grant from the National Council for Research and Development, Israel, and the GKSS Geesthacht-Tesperhude, Federal Republic of Germany     

Development of muscarinic cholinergic receptor binding in the visual system of monocularly deprived and dark reared rats

In 25 day old rats monocularly deprived by unilateral eyelid suture on postnatal day 10 (MD), [³H]quinuclidinyl benzylate (³H-QNB) binding was significantly reduced in the visual cortex (VC) of both sides, but elevated in both superior colliculi (SC). Muscarinic receptor binding in the frontal cortex (FC), a non-visual brain area, in the lateral geniculate nucleus (LGN), and in the retina was not affected. In 25 day old rats raised in complete darkness from birth (DR) similar changes in³H-QNB binding were found in VC and SC. However, binding levels were also decreased in the FC and significantly increased in the retina. In adult (6 month old) MD and DR rats the differences in³H-QNB binding as compared to age-matched controls had disappeared completely in all visual brain areas studied. Detailed Scatchard analyses indicate that the alterations in the³H-QNB binding were due to changes in receptor number only.This paper is dedicated to Dr. Derek Richter on his seventy-fifth birthday.     

Fine structure of the coelomic epithelium of Sagitta elegans (Chaetognatha)

Summary The coelomic space in the trunk of the arrow worm Sagitta elegans is lined by a thin epithelium, which may be termed coelomic epithelium. The visceral part of this epithelium is composed of flat cells characterized by thin and thick myofilaments, which constitute the circular musculature of the gut. In addition mitochondria, rough ER, and smooth walled cisterns, as well as vesicular and granular inclusions occur; the apical and basal plasma membranes exhibit no particular specializations. The parietal epithelium is exceedingly thin and covers the muscle cells of the body wall. In the lateral fields columnar ciliated cells are to be found which are rich in rough ER cisterns and which apparently are also coelomic epithelial cells.     

Transdifferentiation and regeneration in vitro

Striated muscle tissue and endoderm can be isolated from the anthomedusa Podocoryne carnea. The isolates are uncontaminated by other cell types and can be cultivated in artificial seawater for months without undergoing autonomous regeneration. However, if the endoderm is combined with collagenase-treated striated muscle, a regeneration process is initiated which leads to the formation of the sexual and feeding organ (manubrium) of the medusa. The original endoderm and striated muscle are replaced in the regenerate by at least seven new cell types, including gametes. Labeling experiments with [³H]thymidine and experiments in which mitosis is inhibited in either the striated muscle or the endoderm with mitomycin C demonstrate that the striated muscle is able to transdifferentiate into all the cell types found in the regenerate. With the possible exception of ectodermal smooth muscle this statement is also valid for the endoderm.