Transmission and scanning electron-microscopic observations on tanycytes in the mediobasal hypothalamus and the median eminence of adrenalectomized rats

Summary Tanycytes in the median eminence (ME) of the rat exhibit morphological features suggesting their possible participation in transport phenomena. After adrenalectomy, which modifies the hypothalamo-hypophyseal axis, they undergo morphological changes characterized by an accumulation of lipid droplets, an increased number of bleb-like protrusions at their apex, as well as an increased pinocytosis of intraventricularly injected horseradish peroxidase (HRP). In addition, after adrenalectomy an increased number of vacuoles appears at the level of the tubero-infundibular sulci. Their intracellular location in the tanycytes is demonstrated by an intraventricular injection of HRP. The significance of these vacuoles is discussed in relation to the hydroelectrolytic modifications associated with the state of adrenalectomy.Supported by a Fonds Lekime-Ropsy AwardSupported by grants: 20472 from the Fonds de la Recherche Scientifique Médicale; and 40025 from the Fonds National de la Recherche Scientifique     

A unique origin for Sicilian (δβ)∘-thalassemia in 33 unrelated families and its rapid diagnostic characterization by PCR analysis

Direct sequencing and restriction enzyme digestion of the polymerase chain reaction (PCR) product encompassing the breakpoint were used to characterize the Sicilian ()-thalassemia deletion in 33 unrelated Italian subjects. All cases showed the same sequencing features at the breakpoint region, suggesting a unique origin for this deletion in Italy. We also describe a one-step PCR assay for the rapid screening of homozygotes and carriers of Sicilian ()-thalassemia by the simultaneous use of three specific oligonucleotides. This procedure could have an impact on genetic counseling of couples at risk for this type of thalassemia, and with respect to compound heterozygotes bearing a Sicilian chromosome.     

A numerical classification of yeasts of the genusPichia hansen by a factor analysis method

A method of factor analysis was used to establish the relationships between 30 species of a group of yeasts namedPichia on the basis of factors (groups of characters) of decreasing importance.associated to the C.N.R.S. (Centre National de la Recherche Scientifique).     

Requirement for nonprotonated drug molecules in the direct lethal action of miconazole against Candida albicans

At 10^–5 M, miconazole (MCZ) can exert a direct physicochemical cell-damaging lethal action against logarithmic phase yeasts of Candida albicans. The imidazole moiety of MCZ has a pKa 6.5. Thus, in media of pH >6.5 most drug molecules are nonprotonated (MCZ). Conversely, at pH < 6.5 the majority are protonated and carry a positive charge (MCZH⁺). Our earlier work suggesting that MCZ is required for direct lethal action was tested further. In support of such a requirement, we established a minimal lethal concentration of MCZ (i.e. 5×10^–6 M) that was relatively independent of pH, MCZ concentration, and MCZMCZH⁺ ratio.     

Production of a thermostable alkali-tolerant xylanase from Bacillus circulans AB 16 grown on wheat straw

Bacillus circulans AB 16 was able to produce 50 IU/ml of xylanase, with negligible cellulase activity when grown on untreated wheat straw. The pH optimum of the crude enzyme was 6–7 with a temperature optimum of 80 C. The enzyme showed high pH and thermal stability retaining 100% activity at 60 C, pH 8 and 9 after 2.5 h of incubation. The residual activity at 70 C after 2.5 h was 62% and 45% at pH 8 and 9, respectively. At 75 C only 22.2% activity remained at pH 8 after 1 h incubation. Since Kraft pulp is alkaline this enzyme could be used for prebleaching of pulp at temperatures up to 70 C without pH adjustment.     

Enhanced acetyl esterase production by Fusarium oxysporum

Production of acetyl esterase (EC 3.1.1.6) by Fusarium oxysporum strain F3 was enhanced by optimization of growth conditions. Under optimal conditions, activities as high as 0.89U/ml of culture medium were obtained. The culture filtrate was equally active on p-nitrophenyl acetate and acetylxylan. The enzyme produced 71% deacetylation of acetylxylan in 2h at 40C. Activity was optimized at pH6.5 and at 55^C. The respective K_m values for p-nitrophenyl acetate and acetylxylan were 0.25mM and 1.05% (w/v) and the V_m values were 0.65 and 0.43mol acetate/min/mg protein.     

Analyse des échanges de chromatides dans les cellules somatiques humaines

A new technique (BUdR treatment followed by acridine orange staining) allowing a differentiation of sister chromatids is described. A statistical analysis of 91 human karyotypes gives an estimate of the frequency of exchanges. The mean of sister chromatid exchanges is 27,3 and the minimum number is 11 per cell. — The frequency of these exchanges is proportional to the relative length of each chromosome, and the accumulation of several exchanges in some segments evokes the possibility of a negative interference. — The analysis of endomitoses treated with BUdR during at least two generations is not in disagreement with the model of semi-conservative replication of chromosomal DNA, but the modifications of the chromatids may result from a completely different process. — The frequency of endomitoses is increased by the treatment. These endomitoses allow a very precise analysis of the evolution of the sister chromatid exchanges, during two successive cellular generations.

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Travail de l'E.R.A. N 47 du C.N.R.S. et C.E.A. Contrat N 293.     

Effect of pimozide on the cytology of the eel pituitary

Summary Pimozide, a specifie blocker of dopaminergic receptors, was injected for 4 or 9 days in freshwater (FW) eels or eels acclimated to sea water (SW) for 10 or 30 days. The daily dose was 100 or 200 g/100g. Melanophore index values increase in FW and in 1 month-SW injected eels. All the treated fish react by a total or subtotal degranulation of the lead-hematoxylin positive cells in the pars intermedia. These cells were previously identified as -MSH-secreting cells. The MSH cell nuclear area is significantly increased, nucleoli are larger and the endoplasmic reticulum more developed. The intensity of the response is similar in FW and SW eels, but it does not increase with the higher dose. The rapid release of pituitary -MSH is also visualized by immunofluorescence and immunoenzymologic techniques. No effect on the second cell type of the pars intermedia (PAS-positive cell) is detected. The amount of neurosecretory material is often reduced in the neurohypophysis. These results suggest that the hypothalamic inhibitory control of MSH release and synthesis is mediated through dopaminergic fibers in the eel, but other factors cannot be ignored in this regulation.The author is grateful to Dr. P.A.J. Janssen for donating the pimozide used in this experiment and to Jacqueline Olivereau, from the C.N.R.S., for her excellent technical assistance. This work was supported by the Centre National de la Recherche Scientifique and a grant from the Délégation Générale à la Recherche Scientifique et Technique (n A 650 1588)     

Slow growth phenotype - A possible approach to improved plasmid maintenance in Saccharomyces cerevisiae

Summary Transformation-induced slow growth phenotype (SGP) in yeast is repressed in the presence of 2m plasmids. A full 2m-sequence-based recombinant plasmid (pJB502) was found to be more stable in a 2m-free- [cir] strain of Saccharomyces cerevisiae than in a cir⁺ strain. This could not be attributed to differences in growth rate calculated from kinetic analysis of plasmid loss, but transformed [cir] isolates, which had lost the recombinant plasmid, exhibited varying degrees of SGP in batch culture. One of these isolates was outcompeted in chemostat culture by the recombinant-plasmid-containing strain, suggesting that improved plasmid maintenance can result from SGP in cir hosts.     

Biochemical genetics of bacterial sporulation

Summary The development of membrane structures during the early steps of spore formation was reexamined. These steps include the formation of a ringshaped membrane invagination in contact with a mesosome, the growth of which leads to a straight closed double-membrane diaphragm with a cell wall spike (ringshaped thickening) at its base. Later the diaphragm protrudes into the sporangial cytoplasm in the form of a half-blown balloon. The last step toward completion of the prespore consists of the detachment of the diaphragm from the cell wall spike and its growth (probably from a new growing region) into a completely closed spherical structure.Some of the sporulation mutants are blocked at one of these steps, others present abnormal structures. Bilateral development, the occurrence of multiple membrane invaginations and derepression of cell wall growth are at the origin of certain abnormal mutants. In other mutants the diaphragm is not detached from the cell wall spike, perhaps because of the lack of initiation of a new membrane growth site. This leads to abnormal hemisphere prespores. Satellite prespores have been also observed and attributed to derepressed growth of the cell wall spike.The author was on leave of absence from the Centre National de la Recherche Scientifique, Paris. Present adress: see end of paper.     

Ultrastruttura della Pars distalis dell'ipofisi di Lacerta s. sicula Raf., nei maschi in attività sessuale ed in quelli castrati

Riassunto Facendo seguito ad uno studio in microscopia ottica sull'ipofisi della Lacerta s. sicula Raf. durante vari periodi dell'anno, gli AA. espongono, per la stessa specie, i dati ultrastrutturali per le cellule adenoipofisarie, di maschi ancora in periodo di attiva spermatogenesi e di accoppiamento, e di altri castrati e sacrificati dopo 3–4 mesi. In base alla localizzazione nella ghiandola ed alle variazioni dopo castrazione, si distinguono cellule del 1 tipo (STH) con granuli rotondeggianti ed uniformi (circa 310 m ), cellule del 2 tipo (gonadotrope) a granuli polimorfi, cellule del 3 tipo (pure gonadotrope) a granuli tondi e piccoli (150–270 m) e a globuli di 700–800 m, e cellule del 4 tipo a granuli piccoli ed uniformi (100–200 m), di dubbio significato. Presentano dati a favore dell'ipotesi che la condensazione del secreto in forma di granuli avvenga nelle cisterne del Golgi. Osservano fenomeni di degenerazioni cellulari ed aspetti di distruzione citoplasmatica con liberazione di granuli negli spazi tra le cellule. Negli animali castrati notano degranulazione e segni di intensa attività delle cellule del 2 e del 3 tipo, oltre alla comparsa di cellule vacuolizzate, per dilatazione del reticolo endoplasmico ruvido.

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The ultrastructure of the pars distalis of the hypophysis in sexually active and castrated males of Lacerta s. sicula Raf

Summary In addition to light microscopic studies on the hypophysis of the lizard, Lacerta s. sicula Raf., during different periods of the year, the authors of this paper explain the ultrastructure of the adenohypophysial cells of normal sexually active male lizards and of castrated lizards. On the basis of the location and the structural variations after castration several hypophysial cell types can be distinguished: Type 1 (STH) with spheroid granules (about 310 m diameter); type 2 with polymorphous glycoprotein granules; type 3 with small round granules (150–270 m diameter) and globules of about 700–800 m diameter (both gonadotropes). A fourth cell type with small uniform granules (diameter about 100–200 m has also been observed; its function is uncertain. A condensation of secretory granules in the Golgi complex and phenomena of cellular degeneration and cytolysis followed by a release of granules into the cellular interstices have been observed. In castrated animals degranulation and signs of an increased activity in the cell types 2 and 3 have been shown. In these animals the cisternae of endoplasmic reticulum become greatly distended.

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Lavoro eseguito con il contributo del Consiglio Nazionale delle Ricerche, Impresa Endocrinologia, e svolto, per le osservazioni, presso il Centro di Studio di Microscopia Elettronica della Facoltà di Scienze dell'Università di Napoli; ringraziamo il Prof. Gianfranco Ghiara per la continua critica costruttiva e il dott. Carlo Taddei per i suggerimenti nelle tecniche di microscopia elettronica.     

Meiotic studies ofElymus nutans andE. jacquemontii (Poaceae,Triticeae) and their hybrids withPseudoroegneria spicata and seventeenElymus species

Hybridizations ofElymus nutans andE. jacquemontii were carried out with one species ofPseudoroegneria (S genome), and 20Elymus species, each containing either of the SH, SY, SYH, or SYW genomes. Chromosome configurations were analysed at metaphase I of the two target taxa and their interspecific hybrids. It is concluded that (i)E. nutans is an allohexaploid containing the SYH genomes, andE. jacquemontii is an allotetraploid having the SY genomes; (ii) the genomic affinity is associated with the geographic distance between the species studied; (iii) minor genomic structural rearrangements have occurred within the hexaploid taxon ofE. nutans.     

Molecular screening and fetal diagnosis of β-thalassemia in the Italian population

Summary This paper reports our experience of molecular screening and fetal diagnosis of -thalassemia in 457 at risk couples of Italian descent. Molecular screening was carried out by dot blot analysis on amplified DNA with oligonucleotide probes complementary to the eight most common mutations in Italians [39 (CT); 6 (-A); ⁺-87 (CG); ⁺ IVSI nt 110 (GA); IVSI nt 1 (GA); ⁺ IVSI nt 6 (TC); IVSII nt 1 (GA); ⁺ IVSII nt 745 (CG)]. By using this approach, we have been able to define the mutation in 92.8% of cases. The rest (all but four) were defined by direct sequencing and this led to the detection of nine rare mutations [76 (-C); ⁺ IVSI nt 5 (GA); ⁺ IVSI nt 5 (GC); ⁺ IVSI -1 (cod 30) (GC); ⁺-87 (CT), -290 bp del.; ⁺-101 (CT)], and to the characterization of a novel mutation consisting of the deletion of the G at the invariant AG of the IVSII splice acceptor site of the -globin gene ( IVSII nt 850-1 bp). In the remaining four cases, the -globin gene showed entirely normal sequences and the -globin gene cluster was intact, as indicated by Southern blot analysis. Fetal diagnosis was carried out by dot blot analysis with the oligonucleotide probes defined in the parents. The procedure is simple and reliable, and the results can be obtained within 1 week of sampling. No misdiagnosis has so far occurred. The results indicate that fetal diagnosis of -thalassemia by DNA analysis may be obtained in practically all cases (even in a population showing marked heterogeneity of -thalassemia) by the combination of dot blot analysis for detecting common mutations, and direct sequencing for defining those that are uncommon.     

Intracellular sites of the synthesis of sweet potato mitochondrial F1ATPase subunits

Summary Five subunits (-, -, -, - and -subunits) of the six -and -subunits) in the F₁ portion (F₁ATPase) of sweet potato (Ipomoea batatas) mitochondrial adenosine triphosphatase were isolated by an electrophoretic method. The - and -subunits were not distinguishable immunologically but showed completely different tryptic peptide maps, indicating that they were different molecular species. In vitro protein synthesis with isolated sweet potato root mitochondria produced only the -subunit when analyzed with anti-sweet potato F₁ATPase antibody reacting with all the subunits except the -subunit. Sweet potato root poly(A)⁺RNA directed the synthesis of six polypeptides which were immunoprecipitated by the antibody: two of them immunologically related to the -subunit and the others to the - and -subunits. We conclude that the -subunit of the F₁ATPase is synthesized only in the mitochondria and the -, - and -subunits are in the cytoplasm.     

Conservation status of parrot populations in an Atlantic rainforest area of southeastern Brazil

A census of four species of syntopic parrots was carried out using distance sampling methods on São Sebastião island, SE Brazil. Most of the 33593 ha island is covered by mature and secondary Atlantic rainforest. Almost 80% of these forests are within the Ilhabela Park. Although the species counted have marked differences in size and weight, density (individuals/km²) and estimated population size in 23500 ha of well-preserved forests were similar: Amazona farinosa (13.82±5.94; 3247±1395), Pionus maximiliani (15.79±7.04; 3712±1654), Brotogeris tirica (15.05±4.87; 3537±1143) and Pyrrhura frontalis (13.06±5.53; 3068±1298). Encounter rates of Forpus crassirostris and Pionopsitta pileata were very low, which suggests that there is only a small population of these species on the island. The São Sebastião forests still support healthy populations of parrots. Although woodpecker population estimates on the island are large enough to provide nesting sites for parrots, competition for holes with other secondary cavity nesters such as toucans, flycatchers and tytiras, and the selective cutting of dead trees for canoe construction, which is a common practice on the island, may limit hole availability for parrots.     

Solution conformations of proline rings in proteins studied by NMR spectroscopy

Summary Three different conformations of proline rings in a protein in solution, Up, Down and Twist, have been distinguished, and stereospecific assignments of the pyrrolidine -, - and -hydrogens have been made on the basis of ¹H-¹H vicinal coupling constant patterns and intraresidue NOEs. For all three conformations, interhydrogen distances in the pairs -³, ³-³, ²-², ²-², and ³-³ (2.3 Å) are shorter than those in the pairs -², ²-³, ³-², ²-³, and ³-² (2.7–3.0 Å), resulting in stronger NOESY cross peaks. For the Up conformation, the ³-² and ²-³ spin-spin coupling constants are small (<3 Hz), and weak cross peaks are obtained in a short-mixing-time (10 ms) TOCSY spectrum; all other vicinal coupling constants are in the range 5–12 Hz, and result in medium to strong TOCSY cross peaks. For the Down form, the -², ²-³, and ³-² vicinal coupling constants are small, leading to weak TOCSY cross peaks; all other couplings again are in the range 5–12 Hz, and result in medium to strong TOCSY cross peaks. In the case of a Twist conformation, dynamically averaged coupling constants are anticipated. The procedure has been applied to bovine pancreatic trypsin inhibitor and Cucurbita maxima trypsin inhibitor-V, and ring conformations of all prolines in the two proteins have been determined.     

Fine structural localization of acid and alkaline phosphatase activities in the absorbing cells of the duodenum of rodents

Summary The morphology of the absorbing cells of the duodenal villi in the mouse, the rat, the hamster and the guinea-pig is described. The polymorphism of the dense bodies is pointed out. The fine localization of acid and alkaline phosphatase is investigated and compared. In all the species, acid phosphatase activity is observed in the dense bodies, Golgi vesicles and rare smooth endoplasmic profiles. Alkaline phosphatase is localized on the microvilli, Golgi apparatus, some smooth endoplasmic cisternae and numerous dense bodies. The presence of an alkaline phosphatase reaction in the dense bodies, probably lysosomes, of the absorbing cells is discussed. It is assumed that this enzyme follows a catabolic pathway and is finally degraded in the lysosomes.Abbreviations used AlPase alkaline phosphatase - AcPase acid phosphatase This work was done thanks to the contract C.E.N./A.I.E.A. N 347/RB and thanks to grants from the Fonds de la Recherche scientifique fondamentale collective.     

La forêt alluviale du mont-dieu

Sans résuméReçu par la rédaction le 15.XII.1958.Etude subventionnée par le Fonds National de la Recherche Scientifique de Belgique, dans le cadre des Recherches sur les migrations des Flores et des Végétations dans le Bassin de la Meuse.     

The electrical response ofAvena coleoptile cortex to auxins

Solute mobilities of 28 compounds in isolated cuticular membranes (CM) from Capsicum annuum L. fruit, Citrus aurantium L. and Pyrus communis L. leaves were studied using unilateral desorption from the outer surface. First-order rate constants of desorption (k^*), which are directly proportional to the diffusion coefficient in the waxy outer limiting skins of cuticles were measured. When log k^* was plotted vs. molar volumes of test compounds linear graphs were obtained. The y-intercepts of these graphs (k^*) represent the mobility of a hypothetical molecule having zero molar volume and the slopes of the graphs () represent the size selectivity of the barrier and are related to the free volume available for diffusion. Thus, solute mobilities in cuticles are composed of two independent terms which are subtractive. If k^* and are known, k^* can be estimated for any solute from its molar volume (V_x) using the equation log k^*=log k^* –V_x. These parameters were used to analyse the effects of plant species, extraction of cuticular waxes and molecular structure of solutes on solute mobilities in plant cuticles. For aliphatic solutes, k^* was a factor of 10 smaller than for cyclic compounds, while was 0.011 and 0.012, respectively. The k^*-values for CM of the three species were very similar, but was higher for bitter-orange CM (0.012) than for those of pepper fruits and pear leaves (0.009). This has the consequence that differences in solute mobilities (k^*) among cuticles from different plan species increase with increasing molar volumes of solutes. Our data and our analysis provide evidence that constituents of cuticular waxes are mobile, at least in the solid amorphous wax fraction, but mobility decreases rapidly with increasing molar volume. For instance, if amounts to 0.01, mobilities of wax monomers decrease by a factor of 10 for every increase in molar volume of 100 cm³ · mol^–1. Thus, hexadecanoic acid is quite mobile in the amorphous wax fraction of Citrus (k^*=1.5×10^–6·s^–1), but for dotriacontane having twice the molar volume, k^* was only 2.5×10^–9·s^–1, which is almost three orders of magnitude smaller. Wax esters have even higher molar volumes and their mobilities will be even smaller (about 4×10^–12·s^–1 for a C₄₈-ester). Since low chain mobilities are a prerequisite for low mobilities and permeabilities, the selective advantage of high-molecular-weight wax monomers in plant cuticular waxes becomes obvious. Extracting cuticular waxes from pear leaf CM increased solute mobilities by a factor of 182, but it had no effect on size selectivity. We interpret this result as evidence to the effect that cuticular waxes reduce mobility by increasing tortuosity of the diffusion path, rather than by decreasing the mean free path of diffusional jumps and jump frequencies of diffusants.Abbreviations CM cuticular membrane(s) - 2,4-D 2,4-dichloro-phenoxyacetic acid - LAB lactic acid buffer - MX polymer matrix membranes - UDOS unilateral desorption from the outer surface