Beta-adrenergic receptor-linked adenylate cyclase in rat posterior pituitary

A specific β-adrenergic-stimulated cyclic AMP generating system has been evidenced in rat posterior pituitary. This is clearly demonstrated by: 1) the adenylate cyclase (AC) affinity for stimulants was in the order ISO > NA > DA, and 2) propranolol, a specific β-adrenergic receptor blocker, was the only antagonist of the system. Clonidine and apomorphine were completely inactive, thus excluding an α-adrenergic and/or dopaminergic component in this AC system. Our data also indicate that dopaminergic receptors present in both pituitary lobes are not coupled to an AC.     

Keratinolytic and keratinophilic fungi in the soils of Papua New Guinea

A study was made of soil samples collected during an expedition to the Highlands of Papua New Guinea. Fungi were isolated from the samples by the method of hair baiting (To-Ka-Va). Of the 33 species isolated, about half showed keratinolytic activity. Such activity is previously unreported for Mucor hiemalis f. hiemalis, Myrothecium roridum, Paecilomyces carneus, P. marquandii, Penicillium brevicompactum, Rhinocladiella mansonii and Verticillium lecanii. The species most active keratinolytically were Chrysosporium an. Arthroderma cuniculi, C. an. A. curreyi, C. indicum, Myceliophthora vellerea and Trichophyton ajelloi. The spectrum of fungi with keratinolytic activity isolated from the different sites differed considerably according to the frequency of use by man, heaviest use being correlated with greatest activity. The pH of the soil (varying from 5.8–7.5) had little influence on the type of such fungi isolated.     

Keratinolytic and keratinophilic fungi of children's sandpits in the city of Turin

Soils rich in keratinic residues constitute a permanent or occasional reservoir for dermatophytes and keratinolytic and keratinophilic fungi, and are a source of potential infection for man and animals.The keratinolytic and keratinophilic mycoflora of 28 sandpits in Turin was studied to evaluate the risk of fungal skin infections that is run by children as they play in public parks and to lay the ground-work for a next epidemiological study of soil- and animal-inhabiting dermatophytes found in cities, and their impact on human dermatophytoses. Fifty seven species were isolated and a high percentage (52%) showed keratinolytic activity. Species of Microsporum, Trichophyton, Mariannaea, Aphanoascus, Chrysosporium, Malbranchea and Geomyces showed the most active keratinolysis.Work n. 315 performed under the auspices of the Centro di Studio sulla Micologia del Terreno del C.N.R. at the Dipartimento di Biologia vegetale dell Università di Torino.     

Observations sur la spécificité de la coloration aux acides phosphotungstique et phosphomolybdique

Résumé Les Auteurs ont démontré que, en conditions histochimiques sur du matériel fixé au formol, les acides phosphotungstique et phosphomolybdique ont une double action: 1. une action oxydative à la charge des radicaux PAS-positifs (vic-glycols et éthyleniques) en milieu aqueux, et à la charge des radicaux aminiques en milieu anhydre; cette action entraine la transformation de ces radicaux en aldéhydes; 2. la formation d'une liaison chimique entre les aldéhydes et les molécules des acides phosphomolybdique et phosphotungstique. — La coloration du collagène, au contraire, n'est pas due ni aux radicaux aminiques ni vic-glycols et implique un mécanisme encore inconnu.

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Observations about the specificity of staining of phosphotungstic and phosphomolybdic acid

Summary The authors demonstrated that phosphotungstic and phosphomolybdic acid applied to formol-fixed tissues explete two following actions: 1. An oxidative action on the PAS-positive radicals (double bonds, vic-glycols groups) if in water solution and on aminogroups if in anhydrous solution. This oxidation results in a production of aldehydic radicals 2. The formation of chemical bonds between the aldehydic new-formed groups and the molecules of phosphotungstic or phosphomolybdicacid.— However, the above mentioned mechanism of action is not applicable to the collagen staining for which a different explanation has to be supposed.

     

Developmental changes of choline acetyltransferase (ChAc) activity in chick embryo spinal and sympathetic ganglia

The ChAc activity of spinal and sympathetic ganglia was measured throughout the embryonic life of the chick. In spinal ganglia, the ChAc activity reached a first peak when the maximal proliferation of neuroblasts occurred. Then, the relative ChAc activity decreased. After the 12th day of incubation, the enzyme activity increased again and reached a second peak on the 16th day. In sympathetic ganglia, the general course of the development of ChAc activity was similar to spinal ganglia. However, higher enzymic activity was found. Furthermore, the earlier peak of ChAc activity occurred 48 hr later than the corresponding peak in spinal ganglia. The behaviour of ChAc activity in these two areas of the developing nervous system is interpreted as a function of their histogenesis.     

Transforming growth factor-beta induces cytoskeleton and extracellular matrix modifications in FRTL-5 thyroid epithelial cells

The action of transforming growth factor-beta (TGF-beta) on the morphology, cytoskeleton and extracellular matrix was investigated in FRTL-5 thyroid epithelial cells. After treatment with TGF-beta, FRTL-5 cells became flat and developed straight and thick bundles of actin microfilaments. This effect of TGF-beta was observed even in the presence of thyrotropin, which has a strong microfilament disrupting action. TGF-beta also influenced some aspects of the extracellular matrix organization. Immunofluorescence staining of FRTL-5 cells revealed both the appearance of a fibrillar array of fibronectin in association with the basal plasma membrane and a change in the morphology of basally located laminin patches. TGF-beta induced the formation of adhesion structures at the ventral portion of the cell membrane. Vinculin was focally concentrated at the end of stress fibers in areas corresponding to focal adhesions as revealed by interference reflection microscopy (IRM). The ability to modulate cytoskeleton organization and extracellular matrix protein distribution might mediate some of the reported TGF-beta effects on the expression of specific functional properties in thyroid cells.     

Kinetics of tert-[35S]Butylbicyclophosphorothionate Binding in the Cerebral Cortex of Newborn and Adult Rats: Effects of GABA and Receptor Desensitization

Abstract: The effects of GABA on the kinetics of tert -[³⁵S]butylbicyclophosphorothionate ([³⁵S]TBPS) binding to the convulsant site of GABA_A receptors were studied in membrane suspensions from the cerebral cortex of newborn (1-day-old) and adult (90-day-old) rats. TBPS dissociation was biphasic in neonates and adults, indicating that more than one interconvertible state of [³⁵S]TBPS binding sites may be present in the cerebral cortex. In the absence of GABA, the fast ( t _1/2, 11 min) and slow ( t _1/2, 77 min) components of TBPS dissociation in newborn rats were approximately fourfold slower than in adults. The acceleration of the dissociation rates caused by 2 µ M GABA, however, was more robust in neonates than in adults (six- to ninefold vs. twofold increase, respectively). Moreover, the dissociation rates of TBPS in membranes preincubated with 2 µ M GABA (dissociation started by adding 40 µ M picrotoxin) were two- to fourfold slower than in membranes preincubated without GABA (dissociation started by adding 40 µ M picrotoxin plus 2 µ M GABA). Taken together, these results suggest that (1) the closed state of GABA_A receptors is associated with a more effective steric barrier for the binding of TBPS in neonates compared with adults, (2) GABA produces a larger acceleration of the binding kinetics of TBPS in neonates than in adults, and (3) long incubations with GABA may cause receptor desensitization, which in turn slows down the dissociation rates of TBPS.     

Fungal biodiversity in the air of Turin

The qualitative fungal composition of Turin 's atmospheric environment was surveyed, carrying out a twelve-month study and collecting with a single stage volumetric sieve sampler on Dermasel agar supplemented with 0.4 g l^–1 cycloheximide and 0.05 g l^–1 chloramphenicol. We isolated 165 species and 2 varieties of mesophilic fungi from 58 genera and 26 thermotolerant species from 12 genera. Penicillium, Aspergillus, Acremonium, Chrysosporium, Scopulariopsis, Malbranchea, Paecilomyces, Phialophora and Cladosporium were in sequence the genera most rich in mesophilic species; Aspergillus, Penicillium, Chrysosporium and Scopulariopsis the most rich in thermotolerant species. Many of the species isolated are rarely or never recorded in the atmospheric environment. Cycloheximide can thus be said to select among airborne fungi, giving a characteristic picture.Abbreviation CH Cycloheximide - cfu colony forming unit     

Immunocytochemical analysis of phosphatidylinositol-specific phospholipase C in PC12 cells: predominance of the δ isoform during neural differentiation

The rat pheochromocytoma PC12 cell line, which differentiates into sympathetic neurons under nerve growth factor (NGF) treatment, contains at least three phosphoinositidase C (PIC) isozymes, PIC , PIC , PIC . These isozymes have been previously shown to display a different subcellular localization. To determine whether or not NGF induces changes in the presence and/or distribution of PIC isozymes during PC12 neural differentiation, studies were carried out by means of in situ immunocytochemistry. After NGF administration the proliferative activity was progressively reduced to very low levels, as measured by bromodeoxyUridine incorporation, and a neuron-like morphology was displayed by almost all cells. In unstimulated PC12 cells, PIC was detected in the nucleus whereas PIC was only cytoplasmic; PIC was found in both cell compartments. In cells treated with NGF for 3 days, neural processes extended to twice the diameter of the cell body; the isoform was concentrated near the nucleus, while the immunoreactivity of the form remained constant and the form was increased. After 10 days of treatment with NGF, PIC was hardly detectable and PIC immunostaining was considerably decreased. On the contrary, PIC progressively increased and, after 14 days of NGF exposure, fully differentiated cells displayed an intense labelling of cell body and neurites. In the same cells, PIC and PIC were almost negative. These results suggest that NGF dependent neural differentiation is related to the selective down regulation of PIC and and the increase of PIC isozyme associated with the decrease of cell proliferation.     

Identification of P-glycoprotein at the membrane of mast cell secretory granules. An immunofluorescence and protein A-gold electron microscopical investigation

The presence of P-glycoprotein has been investigated in rat peritoneal mast cells by means of immunofluorescence and immunogold electron microscopy, using the specific monoclonal antibody JSB-1. Immunofluorescence studi es showed that the glycoprotein is primarily concentrated in mast cell granules, and little is localized at the plasma membrane. Electron microscope observations revealed a marked accumulation of colloidal gold particles at the granule-coating membranes, whereas decoration of the plasma membrane is much less intense. When mast cells are stimulated to exocytate with compound 48/80, both immunofluorescence and electron microscopy showed concentration of P-glycoprotein reactivity at the plasma membrane level. Indeed, fusion of the granule with the plasma membrane allowed transfer of immunoreactive P-glycoprotein material from the granule-coating membrane to the cell surface membrane. These findings confirmed the presence of P-glycoprotein in mast cells; it is predominantly localized in the granules and is exposed on the cell surface only after exocytosis, suggesting, therefore, a possible physiological role for P-glycoprotein in the secretion of certain mediators. This revised version was published online in November 2006 with corrections to the Cover Date.