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  • Yeast  (51)
  • Rat  (48)
  • Springer  (99)
  • Blackwell Publishing Ltd
  • Nature Publishing Group
  • 1990-1994  (50)
  • 1980-1984  (49)
  • 1925-1929
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  • 1980  (49)
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  • Springer  (99)
  • Blackwell Publishing Ltd
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  • 1980-1984  (49)
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  • 1
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    Springer
    Journal of industrial microbiology and biotechnology 7 (1991), S. 191-195 
    ISSN: 1476-5535
    Keywords: Yeast ; Trehalose ; Osmotolerance ; Viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A total of 12 yeast strains from various genera were examined for their ability to produce ethanol in the presence of high concentrations of glucose. From these studies, the yeastsTorulaspora delbrueckii andZygosaccharomyces rouxii were observed to the most osmotolerant. These osmotolerant yeast strains were also observed to possess high concentrations of intracellular trehalose. Futhermore, these strains were found to be tolerant to long-term storage at −20°C and to storage at 4°C in beer containing 5% (v/v) ethanol. Cells containing high trehalose levels at the time of freezing or cold storage exhibited the highest cell viabilities. Trehalose concentration was observed to increase during growth on glucose, reaching a maximum after 24–48 h. Increasing the incubation temperature from 21 to 40°C also resulted in an increase in intracellular trehalose content. These results suggest that trehalose plays a role in enhancing yeast survival under environmentally stressful conditions.
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  • 2
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    Journal of industrial microbiology and biotechnology 7 (1991), S. 263-268 
    ISSN: 1476-5535
    Keywords: Yeast ; β-Glucanase ; β-Glucosidase catabolite repression ; Sporulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The activities of three glycosidases, β-glucosidase and β(1,3)- and β(1,6)-glucanases have been monitored during growth and blastospore formation inSaccharomycopsis fibuligera. The assays were carried out on the cell-free culture and in a cell-free extract and a wall autolysate preparation from the growing cells. In complex medium containing 1% glucose an increase in the level of all three enzymes was associated with the transition from mycelium to blastospores. When the level of glucose was increased to 5% blastospore formation was repressed and the level of β-glucanases only increased at the end of the fermentation. The β-glucosidase activity increased during the growth phase. In a defined medium in which slow growth in a wholly yeast-like form was observed, growth was not associated with a high level of β-glucanase activity.
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  • 3
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    Monatshefte für Chemie 111 (1980), S. 355-363 
    ISSN: 1434-4475
    Keywords: Cerulenin ; Fatty acid donor ; Inositol deficiency ; Phospholipid biosynthesis ; Triacylglycerols ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Der Umsatz der Lipide vonSaccharomyces carlsbergensis ATCC 9080 wurde nach Vormarkierung mit3H-Ölsäure und14C-Palmitinsäure untersucht. Inositversorgte Zellen zeigen eine Verschiebung der Fettsäuren von den Triacylglycerinen in die Phospholipide, im besonderen in Phosphatidylcholin und Phosphatidylinosit. Eine verstärkte Übertragung der Fettsäuren von Triacylglycerinen auf Phospholipide konnte festgestellt werden, wenn vormarkierte Zellen auf ein Nährmedium, welches Cerulenin enthielt, übertragen wurde. Cerulenin inhibiert die Fettsäuresynthese und ruft in wachsenden Zellen Fettsäuremangel hervor. Inositdefiziente Hefezellen, welche einen erhöhten Triacylglycerinspiegel aufweisen, verwenden diese Triacylglycerine unter Fettsäuremangelbedingungen ebenfalls für die Synthese von Phospholipiden, besonders von Phosphatidylcholin, Phosphatidyläthanolamin und Phosphatidylserin. Da aus früheren Arbeiten bekannt ist, daß inSaccharomyces carlsbergensis praktisch keine β-Oxidation existiert, können die Triacylglyerine in diesem Hefestamm als Speicher für Fettsäuren angesehen werden, welche zur Synthese von Phospholipiden dienen.
    Notes: Abstract The turnover of lipids was studied in the yeast,Saccharomyces carlsbergensis ATCC 9080, after prelabeling of the cells with [3H] oleic acid and [14C] palmitic acid. In inositol supplemented cells, a redistribution of fatty acids from triacylglycerols to phospholipids (mainly phosphatidylcholine and phosphatidylinositol) could be demonstrated. An increased transfer of fatty acids from triacylglycerols to phospholipids was observed when prelabeled cells were transferred to a growth medium containing cerulenin, which inhibits fatty acid synthesis and thus induces fatty acid deficiency in the growing cells. Inositol deficient cells contain increased levels of triacylglycerols, which are equally well utilized for phospholipid (mainly phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine) synthesis under conditions of fatty acid deficiency. The present results together with the previous finding that β-oxidation is practically absent inSaccharomyces carlsbergensis suggest that in this yeast triacylglycerols function as storage of fatty acids which can be mobilized for phospholipid biosynthesis.
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  • 4
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    Journal of industrial microbiology and biotechnology 7 (1991), S. 35-39 
    ISSN: 1476-5535
    Keywords: 2-Deoxy-d-glucose ; Yeast ; Catabolite repression ; Derepression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The non-metabolizable and toxic glucose analogue 2-deoxy-d-glucose (2-DOG) has been widely employed to screen for regulatory mutants which lack catabolite repression. A number of yeast mutants resistant to 2-DOG have recently been isolated in this laboratory. One such mutant, derived from aSaccharomyces cerevisiae haploid strain, was demonstrated to be derepressed for maltose, galactose and sucrose uptake. Furthermore, kinetic analysis of glucose transport suggested that the high affinity glucose transport system was also derepressed in the mutant strain. In addition, the mutant had an increased intracellular concentration of trehalose relative to the parental strain. These results indicate that the 2-DOG resistant mutant is defective in general glucose repression.
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  • 5
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    Current genetics 19 (1991), S. 329-332 
    ISSN: 1432-0983
    Keywords: Mismatch repair ; Plasmid integration ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A single base pair mismatch (G:T or A:C) in the CYC1 gene of the integrative plasmid pAB218 stimulates up to a five-fold integration into the yeast chromosome. Analysis of chromosomal sites of plasmid integration suggests that the mismatch-stimulated integration is not targeted as would be expected if crossovers, localised in the region of the mismatch, were a necessary step in mismatch repair. Instead, the observed mismatch-stimulated plasmid integration could be due to potentially recombinogenic structures formed during mismatch repair, such as single-stranded gaps or denatured DNA regions extending around the plasmid molecule.
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  • 6
    ISSN: 1432-0983
    Keywords: PET genes ; Yeast ; Mitochondria ; ATP synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This study details the characteristics of two temperature-conditional pet mutants of yeast, strains ts1860 and ts379, which at the non-permissive temperature show deficiencies in the formation of three mitochondrially encoded subunits of the ATP synthase complex. By analysis of mitochondrial translation products, and of mitochondrial transcription in temperature shift experiments from the permissive (22°C) to the non-permissive (36°C) temperature, it was concluded that the nuclear mutations in both mutants primarily inhibit synthesis of ATP synthase subunit 9, and that reductions in subunit 8 and 6 synthesis are secondary pleiotropic effects. Following transfer to 36°C, cells of mutant ts379 display a near complete inhibition of subunit 9 synthesis within 1 h, coincident with a marked reduction in the level of the cognate oli1 mRNA. On the other hand, near complete inhibition of subunit 9 synthesis in strain ts1860 occurs after 3 h at 36°C, at which time there is little change in the level of subunit 9 mRNA. In both mutants the mRNA levels for subunits 6 and 8 are not significantly affected at the time of inhibition of subunit 9 synthesis. Provision of an alternative source of subunit 8, translated extra-mitochondrially for import into the organelle, does not overcome the mutant phenotype of either mutant at 36°C, confirming that subunit 8 is not the sole or primary deficiency in each mutant. The mutants indicate that the products of a least two nuclear genes (designated AEP1 and AEP2) are required for the expression of the mitochondrial oli1 gene and the synthesis of subunit 9. The product of the AEP1 gene (defective in mutant ts1860) is required for translation of oli1 mRNA while the AEP2 product (defective in mutant ts379) is essential either for the stability of oli1 mRNA or for the correct processing of precursor transcripts to the mature message.
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  • 7
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    Current genetics 19 (1991), S. 389-393 
    ISSN: 1432-0983
    Keywords: Yeast ; Pichia inositovora ; Linear plasmids ; Killer toxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Pichia inositovora, strain NRRL Y-18709, which contains three linear double-stranded DNA plasmids, pPinl-1, pPinl-2 and pPinl-3, was cured of these plasmids both by growing the strain in the presence of 50 μg/ml bisbenzimide, and by exposure to ultraviolet light. Both cured and uncured strains were tested for growth on a variety of carbon sources. No differences in growth response were detected, indicating no discernible involvement of the linear plasmids in the catabolism of these compounds. Culture supernatants of Pichia inositovora were shown to contain a substance larger than 100 kDa that is toxic to Saccharomyces cerevisiae, strain GS 1688. Toxin activity was optimal in YEPD assay plates containing 50 mM citrate buffer with a pH between 3.4 and 4.2. Culture supernatants from P. inositovora were also weakly active against Cephaloascus albidus, strain NRRL Y-18710, and Citeromyces matritensis, strain NRRL Y-18711. Concentrated supernatants from cured P. inositovora strains did not exhibit these activities, consistent with the hypothesis that this toxic activity is linear plasmid-encoded. Unlike the wellknown Kluyveromyces lactis system or the newly identified P. acaciae system, P. inositovora strains cured of their linear plasmids do not become detectably sensitive to toxin produced by the wild-type strain, suggesting a nonplasmid-encoded immunity function.
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  • 8
    ISSN: 1432-0983
    Keywords: Yeast ; Molecular cloning ; Nitrogen mustard hyper-resistance ; Choline transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The recessive hnm1 mutant allele is responsible for hyper-resistance to nitrogen mustard in Saccharomyces cerevisiae. Transformation with a single-copy HNM1 wild-type allele of such hyper-resistant mutants will restore wild-type sensitivity to nitrogen mustard. By contrast the presence of multi-copy vectors containing HNM1, in either a hyper-resistant hnm1 mutant or an HNM1 wild-type, will lead to a novel, mustard-sensitive phenotype unrelated to defects in DNA repair genes. Gene disruption of HNM1 revealed that this gene is nonessential for cells prototrophic for choline (CHO1) but lethal for cells with a cho1 genotype. Sensitivity to nitrogen mustard of wild-type HNM1, but not of hnm1 mutants, depends on the choline content of the growth medium, with cells grown in choline-free medium exhibiting the highest sensitivity. Sequencing of a 300 bp DNA fragment of HNM1 revealed the identity of this gene with the CTR locus, which is responsible for choline transport in Saccharomyces cerevisiae.
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  • 9
    ISSN: 1432-0983
    Keywords: Mutagen hyper-resistance ; Yeast ; Base sequence ; Gene disruption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A multi-copy plasmid containing the SNQ3 gene confers hyper-resistance to 4-nitroquinoline-N-oxide (4NQO), Trenimon, MNNG, cycloheximide, and to sulfometuron methyl in yeast transformants. Restriction analysis, subcloning, and DNA sequencing revealed an open reading frame of 1950 bp on the SNQ3-containing insert DNA. Gene disruption and transplacement into chromosomal DNA yielded 4NQO-sensitive null mutants which were also more sensitive than the wild-type to Trenimon, cycloheximide, sulfometuron methyl, and MNNG. Hydropathic analysis showed that the SNQ3-encoded protein is most likely not membrane-bound, while the codon bias index points to low expression of the gene.
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  • 10
    ISSN: 1432-0983
    Keywords: Yeast ; Mitochondria ; Intragenic recombination ; Mutant polypeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Recombinational analysis of oxil mutants was performed using a and a mutant strains with the same mitochondrial and nuclear backgrounds, derived from strain 777-3A. In spite of minor inconsistencies the overall map of oxi1 mutations can be constructed on the basis of wild-type recombinant frequencies in the two-point oxi1 − − x oxi1 − crosses. The frequencies of wild-type recombinants varied in a wide range from 0.003% to 16%, reaching the maximal values expected for unlinked mitochondria) markers. No distinct clusters of mutants were observed. The analysis of translation products of oxil mutants showed that all but one of the oxil mutants studied are connected with the conspicuous changes of the polypeptide band corresponding to subunit 11 of cytochrome c oxidase in electrophoresis on polyacrylamide gels. The exceptional G565 mutant showed no conspicuous change in subunit II, but lacked subunit I of cytochrome c oxidase. Various oxi1 mutants seemed to carry premature chain termination mutations. Most of them show a correlation between the length of the putative fragment of subunit II synthesized and the position on the genetic map. The direction of translation is from the V2 to the V60 mutation. The V2 mutation is proximal to cap and V60 proximal to the par locus.
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  • 11
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    Current genetics 2 (1980), S. 61-67 
    ISSN: 1432-0983
    Keywords: Axenomycin ; Ribosome genetics ; Yeast ; Protein synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Axenomycin inhibits protein synthesis in vivo and in vitro in Saccharomyces cerevisiae. The antibiotic acts by binding to ribosomes, most probably to the large ribosomal subunit. Mutant strains resistant to axenomycin appear to contain ribosomes that are not inhibited by the antibiotic. The responsible gene has been mapped on the VII chromosome between the centromere and the leu1 gene.
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  • 12
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    Current genetics 19 (1991), S. 89-94 
    ISSN: 1432-0983
    Keywords: Yeast ; Mitochondria ; Intron ; Mobile
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mitochondrial and nuclear genomes of 21 yeast species belonging to 12 genera have been tested for the presence of sequences similar to seven S. cerevisiae mitochondrial introns (Sc cox1.1,2,3,4,5c, Sc cob.4 and Sc LSU.1) and one K. lactis mitochondrial intron (Kl cox1.2). Some introns, (Sc cox1.4, Sc cob.4, Sc LSU.1 and Kl cox1.2-all group I type), are widely distributed and are found in species with either basidiomycete or ascomycete affinities. This distribution is suggestive of recent sequence transfer between species. The remaining S. cerevisiae introns cross react with an additional species but with no set pattern. Pulsed field gel electrophoretic studies confirm that none of the tested mitochondrial introns cross react with nuclear DNA. These introns are, therefore, mitochondria-specific. Seven strains of K. lactis exhibit striking variability in intron content. In contrast to all mitochondrial introns tested, two introns of nuclear genes (the K. lactis actin gene and the S. cerevisiae RP29B gene) are not detected beyond their source species.
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  • 13
    ISSN: 1432-0983
    Keywords: Yeast ; Pyruvate decarboxylase ; Gene expression ; Codon usage ; Gene fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Three structural genes encode the pyruvate decarboxylase isoenzymes in the yeast Saccharomyces cerevisiae. PDC1 and PDC5 are active during glucose fermentation where PDC1 is expressed about six times more strongly than PDC5. Expression of PDC6 is weak and seems to be induced in ethanol medium. Consequently, pdc1Δ pdc5Δ double mutants do not ferment glucose and do not grow on glucose medium. Spontaneous mutants, derived from such a pdc1 pdc5 strain, were isolated which could again ferment glucose. They showed pyruvate decarboxylase activity due to a duplication of PDC6. The second copy of PDC6 was expressed under the control of the PDC1 promoter, which was still present in the pdc1 strain. However, the resulting PDC1-PDC6 fusion gene could only partially substitute for PDC1: to achieve normal growth and high pyruvate decarboxylase activity strains carrying PDC1-PDC6 required a functional PDC5 gene which is dispensable in a PDC1 wild-type background. Thus, expression of PDC5 depends on the state of the PDC1 locus: low in the PDC1 wild-type background and high in PDC1-PDC6 fusion strains and, as shown previously, in pdc1 mutants. The activation of PDC5 expression in PDC1-PDC6 strains may be due to particular properties of the PDC1-PDC6 fusion protein or simply to the weaker expression of PDC1-PDC6 in comparison to the wild-type PDC1 gene.
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  • 14
    ISSN: 1432-0983
    Keywords: AEP2 ; Yeast ; Mitochondria ; ATP synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The temperature-conditional pet mutant, ts379, of Saccharomyces cerevisiae fails to synthesize mitochondrial ATP synthase subunit 9 at the restrictive temperature due to mutation of a single nuclear locus, AEP2. The inability to synthesize subunit 9 correlates with a lowered accumulation of the cognate oli1 mRNA indicating that the AEP2 product is involved in oli1 transcript maturation or stabilization. The AEP2 gene has been isolated in this study from a wild-type yeast genomic library by genetic complementation of ts379 at the restrictive temperature. A 1740 nucleotide open-reading frame was observed that encodes a basic, hydrophilic protein of 67534 Da which possesses a putative mitochondrial address signal. Disruption of chromosomal DNA within this reading frame produced a non-conditional respiratory mutant unable to synthesize subunit 9, identifying the AEP2 gene. Hybridization analyses indicate that AEP2 is located on chromosome XIII and produces a 2.1 kb poly(A)+ transcript. Two additional open-reading frames were found in close proximity to that of AEP2. The three open-reading frames shared no significant homology with entries in several data bases.
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  • 15
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    Current genetics 2 (1980), S. 207-210 
    ISSN: 1432-0983
    Keywords: Yeast ; Plasmid ; Repair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have developed a system for assaying pyrimidine dimers in the 2 ⇐m DNA plasmid of Saccharomyces cerevisiae, using Micrococcus luteus UV endonuclease to nick dimer-containing plasmid molecules and measuring percentages of nicked and covalently closed circles on agarose gels. UV-irradiation induced dimers in plasmid DNA, in vivo, at the same rate as in chromosomal DNA. After a dose of 20 Joules·m−2, approximately 86% of plasmid molecules had. at least one dimer. After 3 h incubation under normal growth conditions only 4% still retained dimers in a wild-type strain. In a rad1 (excision-defective) mutant 81% of plasmid molecules still had dimers after 3 h, suggesting that excision repair operates to remove dimers from plasmid DNA in wild-type yeast. Dimers can be removed from 2 ,um DNA in a rad1 mutant by photoreactivation.
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  • 16
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    Current genetics 2 (1980), S. 211-214 
    ISSN: 1432-0983
    Keywords: Yeast ; Ribosomal protein dimorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Two-dimensional gel electrophoresis was used in a comparative study of ribosomal proteins from various strains of Saccharomyces cerevisiae. The results demonstrated a case of dimorphism of L8 protein of 60S ribosomal subunit. Of eight strains examined, two strains were one type and six were the other type. The former, which was tentatively designated as altered (A) type, was more acidic than the latter, common (C) type, as shown by mobility difference in pH gradient gel. Heterozygous (A/C) diploid cells contained both types of L8 protein and gave rise to tetrads of 2:2 segregation for A and C types, indicating that the difference of mobility was reflection of the allelic difference of the gene coding for L8 protein.
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  • 17
    ISSN: 1432-0983
    Keywords: Pulsed field gel-electrophoresis ; S1 nuclease sensitive sites ; Repair ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Repair under non-growth conditions of DNA double-strand breaks (DSB) and chromatin sites sensitive to S1 endonuclease (SSS) induced by 60Cobalt-gamma rays were monitored in repair-competent and deficient strains of Saccharomyces cerevisiae by pulsed field gelelectrophoresis. In stationary-phase cells of a repair-competent RAD diploid, and an excision-deficient rad3-2 diploid, SSS are repaired as efficiently as DSB, whereas in a repair-competent RAD haploid, and a rad 50-1 diploid, neither SSS nor DSB are repaired. The rad18-2 diploid repairs DSB well but is defective in SSS repair. Obviously, SSS repair in yeast chromatin, like DSB repair, depends on recombination, but unlike DSB repair depends additionally on RAD18 function.
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  • 18
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    Current genetics 1 (1980), S. 177-183 
    ISSN: 1432-0983
    Keywords: Yeast ; Ribosomal protein alteration ; Cycloheximide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A spontaneous high-level cycloheximide-resistant mutant of the yeast Saccharomyces cerevisiae (strain cy32) is found to have an altered protein of the large subunit (60S) of cytoplasmic ribosomes, namely protein L29. The resistance character segregates together with this biochemical defect and is semidominant in heterozygous diploids. Judged from in vitro susceptibility to inhibition by cycloheximide there are at least 50% resistant ribosomes present in such diploid strains. From these results it is concluded that cycloheximide resistance of mutant cy32 is caused by mutation of a single gene and that it is the structural gene for L29 which is affected. Preliminary genetic mapping data are also reported. They indicate a location of cyhx-32 marker on chromosome 7 near met13.
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  • 19
    ISSN: 1432-0983
    Keywords: Yeast ; Mistranslation ; ψ-factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chromosomal omnipotent suppressor mutations recovered in ψ+ strains of Saccharomyces cerevisiae were brought into ψ− cytoplasm. SUP46, SUP138 and SUP139 acted as dominant omnipotent suppressors in the ψ− cytoplasm though their suppressor activity was substantially reduced. SUP46 and SUP138 conferred recessive thermosensitivity and antibiotic sensitivity in ψ− cytoplasm as in ψ+ cytoplasm. On the other hand, sup111 through sup115, which acted as recessive omnipotent suppressors in the ψ+ cytoplasm, manifested no, or very low, suppressor activity in the ψ− cytoplasm. They, however, still enhanced the efficiency of the SUP29 tRNA suppressor in ψ− cytoplasm. A multicopy plasmid carrying the wild-type SUP35 gene enhanced the efficiency of sup111 in ψ− cytoplasm.
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  • 20
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    Current genetics 2 (1980), S. 175-180 
    ISSN: 1432-0983
    Keywords: Yeast ; Hydroxyurea ; DNA synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Newly synthesised DNA molecules the same size as replicons (7 million-60 million daltons) accumulate in yeast cells treated with hydroxyurea. During prolonged incubation in low concentrations of the drug, there is a large accumulation of these molecules without any corresponding increase in their molecular weight. On release from the inhibtion the molecules are converted to large molecular weight DNA. These observations are consistent with an inhibition by hydroxyurea of the joining of completed replicons. In addition, newly synthesised DNA molecules the size of yeast Okazaki fragments also accumulate in cells treated with hydroxyurea.
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  • 21
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    Current genetics 2 (1980), S. 193-200 
    ISSN: 1432-0983
    Keywords: Recombination ; Plasmids ; Transformation ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary [2 μm+ and [2μm°] yeast were transformed to stable leucine prototrophy with the hybrid yeast — E. coli plasmid, pJDB219. This plasmid contains the entire sequence of the endogenous 2 μm yeast DNA plasmid in addition to the yeast nuclear LEU2 + gene and the Co1E1 derivative, pMB9. In the [2 μm+] transformants, a new wholly yeast LEU2 + plasmid, pYX, was generated, probably by a recombination event between pJDB219 and 2 μm DNA. The plamid, pYX, in the absence of 2 μm DNA, was found to exist in equimolar amounts of two forms, A and B, which probably arise by intramolecular recombination across the inverted repeat sequences of the 2 μm DNA portion of the plasmid. pJDB219 was found to require the presence of 2 μm DNA to undergo this intramolecular recombination. The results suggest that 2, μm DNA and pYX code for a gene product required in this recombination event which pJDB219 cannot produce.
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  • 22
    ISSN: 1432-0983
    Keywords: Yeast ; Mutant ; p-Fluoro-dl-phenylalanine ; β-Phenethyl-alcohol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary p-Fluoro-dl-phenylalanine (PFP)-resistant mutants which produce a large amount of β-phenethyl-alcohol, a rose-like flavor component, were isolated from the isogenic strains X2180-1A and X2180-1B of Saccharomyces cerevisiae. Cells of these mutants accumulated phenylalanine and tryptophan more than 3-fold times that of wild-type cells, while they accumulated less than half the tyrosine. The activity of prephenate dehydrogenase (PDG) (EC 1.3.1.12) was markedly decreased while that of 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase (EC 4.1.2.15) was increased. Genetic analysis revealed that the mutation occurred at the TYR1 locus, encoding PDG, and that the mutated TYR1 gene, tyr1-pfp, caused both PFP resistance and β-phenethyl-alcohol overproduction. This was supported by molecular genetic studies with cloned tyr1-pfp DNA.
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  • 23
    ISSN: 1432-0983
    Keywords: Peptides ; Transport ; Regulation ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The transport of small peptides into the yeast Saccharomyces cerevisiae is subject to complex regulatory control. In an effort to determine the number, and to address the function, of the components involved in peptide transport and its regulation, spontaneous mutants resistant to toxic di- and tripeptides were isolated under inducing conditions. Twenty-four mutant strains were characterized in detail and fell into two phenotypic groups; one group deficient in amino acid-inducible peptide uptake, the other with a pleiotropic phenotype including a loss of peptide transport. Complementation analysis of recessive mutations in 12 of these strains defĩned three groups; ptr1 (nine strains), ptr2 (two strains), and ptr3 (one strain). Isolation and screening of 31 additional N-methyl-N-nitro-N-Nitrosoguanidine (MNNG)-induced, peptide transport-deficient mutants produced one ptr3 and 30 ptr2 strains: no additional complementation groups were detected. Uptake of radiolabeled dileucine was negligible in ptr1 and ptr2 strains and was reduced by 65% and 90% in the two ptr3 mutants, indicating that all strains were defective at the transport step. We conclude that the S. cerevisiae amino acid-inducible peptide transport system recognizes a broad spectrum of peptide substrates and involves at least three components. One gene, PTR3, may play an indirect or regulatory role since mutations in this gene cause a pleiotropic phenotype.
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  • 24
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    Journal of molecular evolution 32 (1991), S. 396-404 
    ISSN: 1432-1432
    Keywords: Yeast ; Mitochondrial DNA ; Polymirphism ; Repeated sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A spontaneously arising mitochondrial DNA (mtDNA) variant ofSaccharomyces cerevisiae has been formed by two exta copies of a 14-bp sequence (TTAATTAAATTATC) being added to a tandem repeat of this unit. Similar polymorphisms in tandemly repeated sequences have been found in a comparison between mtDNAs from our strain and others. In 5850 bp of intergenic mtDNA squence, polymorphisms in tandemly repeated sequences of three or more base pairs occur approximately every 400–500 bp whereas differences in 1–2 bp occur approximately every 60 bp. Some polymorphisms are associated wit optional G+C-rich sequences (GC clusters). Two such optional GC clusters and one A+T repeat polymorphism have been discovered in the tRNA synthesis locus. In addition, the variable presence of large open reading frames are documented and mechanisms for generating intergenic sequence diversity inS. cerevisiae mtDNA are discussed.
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    Journal of molecular evolution 32 (1991), S. 439-442 
    ISSN: 1432-1432
    Keywords: Yeast ; Mitochondrial DNA ; ori ; rep ; Polymorphism
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    Topics: Biology
    Notes: Summary Threeori elements (ori 2,ori 5, andori 7) have been sequenced inSaccharomyces cerevisiae strain Dip 2 and compared to the equivalentori elements of a second strain (B). Bothori 2 andori 5 exhibit 98% base matching between strains Dip 2 and B. In contrast, the thirdori element (ori 7) exhibits extensive sequence rearrangements whereby a segment located downstream in the consensus strain occurs within theori structure in Dip 2. This represents a novel polymorphic form of the yeast mitochondrial genome.
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  • 26
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    Journal of molecular evolution 33 (1991), S. 442-449 
    ISSN: 1432-1432
    Keywords: Humans ; Mouse ; Rat ; Codon usage ; Mutation bias ; Selection
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    Topics: Biology
    Notes: Summary A new statistical test has been developed to detect selection on silent sites. This test compares the codon usage within a gene and thus does not require knowledge of which genes are under the greatest selection, that there exist common trends in codon usage across genes, or that genes have the same mutation pattern. It also controls for mutational biases that might be introduced by the adjacent bases. The test was applied to 62 mammalian sequences, the significant codon usage biases were detected in all three species examined (humans, rats, and mice). However, these biases appear not to be the consequence of selection, but of the first base pair in the codon influencing the mutation pattern at the third position.
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  • 27
    ISSN: 1432-0827
    Keywords: Rat ; Calvarium ; Electron microscopy ; Preosteoclasts ; Osteoclasts
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    Topics: Biology , Medicine , Physics
    Notes: Summary This is a study of the fine structure of cells of the 20-day fetal rat calvarium. Special attention is given to identifying and characterizing preosteoclasts. These cells are relatively common and located largely, but not exclusively, at the endocranial bone surface. The preosteoclasts are characterized by abundant mitochondria, an incomplete perinuclear Golgi apparatus, and variable-shaped dense granules. The dense granules are unique in appearance in that they contain an internal dense matrix surrounded by a clear halo. Most granules are circular in shape but some are elongate or tubular in form. Granules with identical appearance are observed in osteoclasts. The preosteoclasts are mononucleate, or occasionally binucleate. It is suggested that because preosteoclasts are morphologically distinctive and relatively abundant, it should be feasible to separate these cells from a heterogeneous cell isolate.
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  • 28
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    Calcified tissue international 32 (1980), S. 63-68 
    ISSN: 1432-0827
    Keywords: Rat ; Bone formation ; Fluorochrome ; Microphotometry
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    Topics: Biology , Medicine , Physics
    Notes: Summary A method for quantitative studies of the formation rate of bone has been developed. After vital staining with calcein, the fluorescence of a bone section was measured with a microphotometer controlled by a mini computer. After staining the bone structure with alizarin red S in a second step, the section was measured in transmitted light. The two data sets were combined and the shortest distances between the bone surface and the fluorescence lines were computed. With this information the distance distribution and the bone area between the label and the surface could be calculated in two different ways: with the single labeling and the continuous labeling techniques. The advantages and disadvantages of the two methods are discussed and compared with those of other techniques.
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  • 29
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    Calcified tissue international 32 (1980), S. 113-122 
    ISSN: 1432-0827
    Keywords: Rat ; Bone ; Metaphysis ; Quantitative ; Aging
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    Topics: Biology , Medicine , Physics
    Notes: Summary The purpose of this work was to analyze the proximal tibial metaphysis of the 170 g rat in a quantitative histologic fashion which would allow some relation to tissue age to be established. Stained 3 µm thick tissue sections were analyzed with the aid of a Merz grid on an eyepiece reticule and a light microscope. Tissue mass and cell distribution were studied in all areas. The rate of change in tissue mass during aging of the metaphysis was calculated. Two regions of the metaphysis were identified. One, corresponding to the primary spongiosa, less than 4.45 days of age, is a region of high turnover of hard tissue and high numbers of osteoblasts and osteoprogenitor cells. The other, corresponding to the secondary spongiosa, is a region of relatively low net tissue turnover and low numbers of osteoblasts and osteoprogenitor cells. Osteoclasts were found relatively more uniformly distributed through the metaphysis than were osteoblasts and osteoprogenitor cells. The rate of bone formation in the primary spongiosa is 50 times that found in the Haversian bone of the rib of 5-year-old humans and about 500 times that found at the cortical-endosteal surface of ribs of 5-year-old humans. It is argued that both cell distribution and tissue distribution in the metaphysis support the concept that osteoblasts and osteoclasts, rather than osteocytes, are responsible for the maturation of the metaphysis. The inhomogeneous distribution of both cells and tissue in the metaphysis has definite meaning for the interpretation of findings concerning the incorporation of radionuclides into the skeleton.
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  • 30
    ISSN: 1432-0827
    Keywords: Rat ; Hypophysectomy ; Dietary phosphorus deprivation
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    Topics: Biology , Medicine , Physics
    Notes: Summary The demands of growth are known to exacerbate the effect of phosphorus deprivation (PD). We examined whether changes associated with PD could be prevented in young rats in which growth and growth hormone (GH) were eliminated by hypophysectomy (HPX) and whether PD in normal intact rats (INT) was associated with increased secretion of GH. INT or thyroxine- and ACTH-replaced HPX rats were fed one of the three diets: 0.31% P (NP); 0.027% P (LP), and 0.31% P, pair-fed with LP-mates (NP-PF). The results indicate that HPX did not qualitatively alter several physiologic responses to PD: (a) serum and urinary phosphorus (P) decreased and urinary calcium (Ca) increased; (b) net intestinal Ca retention fell and duodenal sac uptake of45Ca rose; and (c) external P balance was restored and duodenal sac uptake of32P-phosphate increased. Only the hypercalcemia seen in INT, LP rats was prevented by HPX. In INT rats serum immunoassayable GH levels, measured in single samples, were not different between different dietary groups while pituitary bioassayable GH was reduced in both LP and NP-PF rats when compared to the NP rats. Thus, except for hypercalcemia, the physiologic responses associated with PD are not prevented by the elimination of growth and GH, and the development of these responses in INT rats was not associated with a consistent or specific alteration in GH secretion.
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  • 31
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    Current genetics 20 (1991), S. 471-474 
    ISSN: 1432-0983
    Keywords: Yeast ; DNA replication ; Chemical mutagenesis
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    Topics: Biology
    Notes: Summary Incubation of cdc8 mutants of the yeast Saccharomyces cerevisiae in YPD under permissive conditions, when DNA replication is taking place, prior to transfer to restrictive conditions, strongly stimulates induction of cdc + colonies of ethyl methane sulphonate (EMS)- and methyl methane sulphonate (MMS)-treated yeast strains HB23 (cdc8-1/cdc8-3), HB26 (cdc8-3/cdc8-3) and HB7 (cdc8-1/cdc8-1). After diepoxybutane (DEB) treatment, both the induction of cdc + colonies and their stimulation after incubation in YPD under permissive conditions is low. The results obtained show that stimulation of induction of cdc + colonies under permissive conditions occurs not only after UV-treatment, but also after treatment with such mutagens as EMS and MMS.
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  • 32
    ISSN: 1432-0983
    Keywords: Petite mutation ; NUC2 nuclease ; Yeast ; RAD52 ; Ethidium bromide
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    Notes: Summary Defects in the RAD52 gene of the yeast Saccharomyces cerevisiae reduce the levels of the NUC2 endo-exonuclease by approximately 90% compared to the levels in wild-type strains. To examine the potential role of this nuclease in the induction of mitochondrial ‘petite’ mutations, congenic RAD52 and rad52-1 haploids were subjected to treatment with ethidium bromide, a well-known inducer of these mutations. The rad52 strain showed a much higher resistance to ethidium bromide-induced petite formation than the corresponding wild-type strain. Two approaches were taken to confirm that this finding reflected the nuclease deficiency, and not some other effect attributable to the rad52-1 mutation. First, a multicopy plasmid (YEp213-10) carrying NUC2 was transformed into a RAD52 strain. This resulted in an increased fraction of spontaneous petite mutations relative to that seen for the same strain without the plasmid and sensitized the strain carrying the plasmid to peptite induction by ethidium bromide treatment. Second, a strain having a nuc2 allele that encodes a temperaturesensitive nuclease was treated with ethidium bromide at the restrictive and permissive temperatures. Petite induction was reduced under restrictive conditions. Enzyme assays revealed that the RAD52 (YEp213-10) strain had the highest level of antibody-precipitable NUC2 endo-exonuclease whereas the nuc2 and rad52 mutants had the lowest levels. Furthermore, addition of ethidium bromide to the reaction mixture stimulated the activity of the nuclease on double-stranded DNA. Peptite induction by antifolate-mediated thymine nucleotide depletion was also inhibited by inactivation of RAD52 indicating that the effect of reduced NUC2 endo-exonuclease was not restricted to ethidium bromide treatment. Taken collectively, these results indicate that the NUC2 gene product functions in the production of mitochondrial petite mutations.
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  • 33
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    Current genetics 20 (1991), S. 1-3 
    ISSN: 1432-0983
    Keywords: Yeast ; Transformation ; Ethanol
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    Notes: Summary A technique is described in which ethanol is used to improve the genetic transformation of intact yeast (Saccharomyces cerevisiae) cells pretreated with LiAc and PEG. Transformation efficiency was increased with increasing concentrations of ethanol with a peak at 10% concentration. The effect varies with different yeast strains and plasmids and up to a maximum of a 15-fold increase was observed.
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  • 34
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    Current genetics 20 (1991), S. 25-31 
    ISSN: 1432-0983
    Keywords: Yeast ; TSM1 sequence ; Essential gene ; MAT distal cloning
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    Notes: Summary We have cloned the region from MAT to THR4 on chromosome III of Saccharomyces cerevisiae. Although the region is only 15 kb, the two loci are genetically separated by 22 cM. This is in sharp contrast to the very low level of recombination (2 cM in 22 kb) that is observed in the adjacent CRY1-MAT interval, and suggests that there may be a “hot spot” for recombination in the MAT-THR4 region. The DNA sequence of the first 4.4 kb distal to MAT reveals an open reading frame that we have identified as the essential gene, TSM1. Surprisingly, the TSM1 open reading frame of 1 410 amino acids extends into the MAT locus, such that the 3′-end of the MATα1 transcript ends 15 bp from the 3′-end of the TSM1 open reading frame.
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  • 35
    ISSN: 1432-0983
    Keywords: Yeast ; Enhancer ; Transcriptional elements ; Transcriptional factors ; Regulation
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    Notes: Summary Though highly complex enhancers found in animal cells have not been reported to occur in yeasts they are able to activate the transcription of adjacent genes in yeast cells. Saccharomyces cerevisiae expresses a large number of nuclear proteins that are able to recognize, and specifically bind to, the enhancer sequences of the SV40 animal tumor virus. The complexity of proteins that interact with different elements of the animal enhancers is similar in yeast and animal cell nuclear extracts. Most enhancer motifs, recognized by known trans-acting factors, are protected in footprinting experiments by yeast nuclear proteins.
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  • 36
    ISSN: 1432-0983
    Keywords: Saccharomyces cerevisiae ; Ergosterol ; Squalene synthetase ; Yeast
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    Notes: Summary The ERG9 gene of Saccharomyces cerevisiae has been cloned by complementation of the erg9-1 mutation which affects squalene synthetase. From the 5kkb insert isolated, the functional gene has been localized on a DNA fragment of 2.5 kb. The presence of squalene synthetase activity in E. coli bearing the yeast DNA fragment isolated, indicates that the structural gene encoding squalene synthetase has been cloned. The sequence of the 2.5 kb fragment contains an open reading frame which could encode a protein of 444 amino acids with a deduced relative molecular mass of 51 600. The amino acid sequence reveals one to four potential transmembrane domains with a hydrophobic segment in the C-terminal region. The N-terminus of the deduced protein strongly resembles the signal sequence of yeast invertase suggesting a specific mechanism of integration into the membranes of the endoplasmic reticulum.
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  • 37
    ISSN: 1432-0983
    Keywords: Mitochondria ; Intron ; Telomere ; Yeast
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    Notes: Summary The junctions between X and Y′ subtelomeric repeats in Saccharomyces cerevisiae usually contain a stretch of telomere sequences, (G1–3T)n. Two of three cloned X-Y′ junctions from strain YP1 have a replacement of about 200 bp of X, the internal telomere sequence, and 49 bp of Y′ by a 292 bp sequence. The first 227 bp of this insertion sequence are 100% identical to the fourth intron of cytochrome b. The rest of the insertion has homology to an unknown dispersed nuclear sequence. Recombination among subtelomeric regions can explain the nuclear distribution of this sequence and why telomeres can trap and maintain sequences that would otherwise be lost.
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  • 38
    ISSN: 1432-0983
    Keywords: In vitro mutagenesis ; PET-genes ; RNA-leader ; Ribosomal scanning ; Yeast
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    Notes: Summary We report that the major transcription start sites of the yeast PET gene SCO1 are located at positions-149 and -125 relative to the AUG initiation codon of the SCO1 reading frame. The leader sequences of the resulting mRNAs possess a single AUG codon at position-49, which initiates a short open reading frame of three amino acids. The recent finding of a similar situation in the case of the PET gene CBS1 prompted us to address the question as to whether these AUG codons might play some role in the expression of these PET genes. After removal of the upstream AUG codons by site-directed mutagenesis, expression was monitored by use of lacZ fusions and compared to the respective wildtype constructs. Our data show that under all growth conditions tested the leader-contained AUG initiation codons have no significant influence on the expression of both PET genes.
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  • 39
    ISSN: 1432-072X
    Keywords: Mating tube ; Microtubule ; Tremella ; Ultrastructure ; Yeast
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    Notes: Abstract Ultrastructure of the mating tube formed in yeast haplont of the heterobasidiomycete Tremella mesenterica was studied by electron microscopy. Cell wall of the mating tube emerged as evagination of the inner layers, rupturing outer layers of the mother cell wall. Comparison with budding cells suggested that the tube emergence place at bud scar and the process of tube emergence was the same as that of bud emergence. Electron transparent vesicles of 0.1 μm diameter were scattered in the cytoplasm of the mating tube. Nucleus-associated organelle was located at one side of the nuclear envelope which extended towards the mating tube. A few microtubules were detected in the mating tube, but their association with a nucleus was not clear. The cytoplasmic structure of the mating tube was discussed in comparison with that of hyphae of the filamentous fungi.
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  • 40
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    Archives of microbiology 124 (1980), S. 285-287 
    ISSN: 1432-072X
    Keywords: Yeast ; Saccharomyces cerevisiae ; Heat killing ; Membrane damage ; Genetic damage ; Growth temperature
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    Topics: Biology
    Notes: Abstract The resistance of exponentially growing yeast cells to killing by exposure to 52°C increased markedly as the growth temperature was increased. Identical killing curves were obtained for cells suspended in growth medium or in 0.9% saline. Cells resistant to killing at 52°C were quite sensitive to killing at slightly higher temperatures. These results suggest a primary role for membrane damage in the mechanism of heat killing.
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    Cell & tissue research 205 (1980), S. 11-17 
    ISSN: 1432-0878
    Keywords: Pineal organ ; Subcommissural organ ; Vasopressin ; Oxytocin ; Vasotocin ; Rat
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    Topics: Biology , Medicine
    Notes: Summary Vasopressin and oxytocin were specifically demonstrated in the rat brain using the unlabelled antibody-enzyme method and purification of the first antiserum. Vasopressin and oxytocin fibres extend via the subcommissural organ or habenular commissure into the pineal stalk and terminate in the anterior part of the pineal organ. In addition, immediately adjacent to the subsommissural organ many vasopressin-containing fibres run caudally toward the central grey. These results are discussed in relation to the proposed presence of vasotocin in the pineal gland.
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  • 42
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    Cell & tissue research 210 (1980), S. 167-170 
    ISSN: 1432-0878
    Keywords: Neuropeptides ; VIP-immunoreactive neurons ; Retina ; Amacrine cells ; Rat
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    Topics: Biology , Medicine
    Notes: Summary Immunoreactive vasoactive intestinal polypeptide (VIP) was detected in a population of amacrine cells in the retina of the rat. Processes of these cells reach both the inner and outer half of the inner plexiform layer where they form sublayers. The VIP neurons are different from previously known amacrine cell types.
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    Cell & tissue research 210 (1980), S. 181-189 
    ISSN: 1432-0878
    Keywords: Catecholamines ; Neurophysin ; Simultaneous demonstration ; Functional interaction ; Rat
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    Notes: Summary A method was developed that allows the analysis of neuropeptides and monoamines in a single tissue section by the application of the unlabeled antibody method for peptide staining to tissue sections freeze-dried for formaldehyde-induced monoamine histofluorescence. The hypothalamic magnocellular system of male albino rats served as a model for this study; neurons were stained with anti-neurophysin sera, which mark the vasopressin- and oxytocin-associated proteins. Neurophysin-containing perikarya appeared to be surrounded by catecholamine-containing varicosities. This phenomenon was seen to varying degrees within the supraoptic and paraventricular nuclei. The juxtaposition of varicosities and peptidergic neurons suggests an afferent fiber-target neuron relationship that might favor a functional interaction between monoamines and neuropeptides.
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  • 44
    ISSN: 1432-0878
    Keywords: Rat ; Preovulatory follicle ; Ultrastructure ; Degeneration ; Atresia
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    Notes: Summary To identify and describe ovarian follicles committed to undergo follicular degeneration (atresia), immature rats were primed with pregnant mare serum gonadotropin (PMSG). After PMSG treatment, preovulatory follicles develop but subsequently degenerate. Prior to the appearance of pyknotic nuclei (Stage I of atresia), degenerative changes were observed in focal areas of the granulosa cell layer. These changes include “blebbing” of the cytoplasm and alterations in the shape of the granulosa cells. The appearance of these degenerative changes coincides with a decrease in ovarian concentrations of estradiol and testosterone. Since estrogens and androgens maintain the follicle, the decline in estradiol and testosterone could be responsible for the further degenerative alterations that lead to complete deterioration of the preovulatory follicle. In Stage I atretic follicles, lysosome-derived autophagic vacuoles develop and macrophages invade both the thecal and granulosa cell layers. The combined actions of the autophagic vacuoles and macrophages could destroy both the granulosa-cell and thecal layers and thereby transform the preovulatory follicle into an ovarian cyst.
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  • 45
    ISSN: 1432-0878
    Keywords: Lymph node ; Macrophages ; Postcapillary high endothelial venules ; Rat
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    Notes: Summary The afferent lymphatic vessels of rat popliteal lymph nodes were interrupted, and the histological alterations in the lymph nodes occurring 1 to 14 weeks after operation were studied. One week after operation the number of macrophages was considerably reduced and continued to decrease during the subsequent time periods studied. A 6 weeks most macrophages had disappeared. Simultaneously the immunological activity diminished and had completely disappeared 8 weeks after operation. Three weeks after operation the endothelial cells of the postcapillary high endothelial venules had flattened, and the number of immigrating lymphocytes was greatly reduced. Subsequently the lymph nodes became depleted of both macrophages and lymphocytes, leaving only the reticuloendothelial framework.
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  • 46
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    Cell & tissue research 265 (1991), S. 425-433 
    ISSN: 1432-0878
    Keywords: Regulatory peptides ; Serotonin ; Protein gene product 9.5 (PGP) ; Respiratory tract ; Neuroendocrine cells ; Mouse ; Rat ; Harnster
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    Notes: Summary The epithelium of the airways is rich in endocrine cells containing serotonin and/or a wide variety of regulatory peptides. These cells usually occur in clusters in the lungs but are also found scattered in the larynx and trachea. In the present study, endocrine cells in the airways of mouse, rat, hamster, guinea pig, pig, sheep and squirrel monkey were examined for the presence of serotonin, helodermin-like peptides and other regulatory peptides using immunocytochemistry and radioimmunoassay. In addition, we looked for the protein gene product 9.5 (PGP), which occurs in many peptide hormone-producing endocrine cells in the body. Both clustered and scattered endocrine cells in the airways were found to display coexistence of serotonin and peptides, such as a helodermin-like peptide, calcitonin and calcitonin gene-related peptide (CGRP). The PGP-immunoreactive cells were numerous and included elements containing serotonin and/or regulatory peptides. An additional PGP-immunoreactive endocrine cell population lacked serotonin and regulatory peptides. Helodermin-immunoreactive material was demonstrated in endocrine cells of the airways in the mouse and hamster but not in any of the other species studied. Serotonin was an endocrine cell constituent in all the species studied. Calcitonin and CGRP could be demonstrated by immunocytochemistry in the mouse, rat, and hamster, but not in the guinea pig, sheep, pig and monkey. In the hamster airways double immunostaining indicated that the helodermin-like peptide occurred in a subpopulation of the CGRP- and serotonin-containing cells. Most of the CGRP-containing cells stored serotonin; some of them also contained calcitonin. The chemical coding of these cells resembled that of the thyroid C cells.
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    Cell & tissue research 265 (1991), S. 555-565 
    ISSN: 1432-0878
    Keywords: Atrial natriuretic peptide ; Brain natriuretic peptide ; Binding sites ; Trachea ; Autoradiography ; Cell culture ; Rat
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    Topics: Biology , Medicine
    Notes: Summary We examined the distribution of binding sites for alpha-atrial natriuretic peptide (125I-ANP1–28) and the recently discovered porcine brain natriuretic peptide (125I-pBNP) on immunocytochemically identified cells in dissociated culture preparations of the rat trachea. Specific binding sites for both 125I-ANP1–28 and 125I-pBNP were evenly distributed over distinet subpopulations of smooth muscle myosin-like immunoreactive muscle cells, fibronectin-like immunoreactive fibroblasts and S-100-like immunoreactive glial cells. Neither keratin-like immunoreactive epithelial cells nor protein gene product 9.5-like immunoreactive paratracheal neurones expressed natriuretic peptide binding sites, although autoradiographically labelled glial cells were seen in close association with both neuronal cell bodies and neurites. The binding of each radiolabelled peptide was abolished by the inclusion of either excess (1 μM) unlabelled rat ANP or excess unlabelled porcine BNP, suggesting that ANP and BNP share binding sites in the trachea. Furthermore, the ring-deleted analogue, Des-[Gln18, Ser19, Gly20, Leu21, Gly22]-ANF4–23-NH2, strongly competed for specific 125I-ANP1–28 and 125I-pBNP binding sites in the tracheal cultures; this suggests that virtually all binding sites were of the “clearance” (ANP-C or ANF-R2) receptor subtype.
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    Cell & tissue research 209 (1980), S. 1-10 
    ISSN: 1432-0878
    Keywords: Myoepithelial cell ; Exocrine gland ; Scanning electron microscopy ; Rat
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    Topics: Biology , Medicine
    Notes: Summary By removing connective tissue components with enzymatic digestion followed by HCl-hydrolysis, myoepithelial cells (MECs) of the terminal portion in a variety of exocrine glands of the rat were examined with the scanning electron microscope. The profile of MECs varied considerably from gland to gland; MECs in the lactating mammary gland have a few long cytoplasmic processes in close contact with those of adjacent cells forming a continuous network around the terminal portion. Those of the exorbital lacrimal gland are stellate with many thin radiating processes with tapered ends that terminate freely. MECs in the sublingual gland are characterized by a number of broad and extensive cellular processes. MECs in the submandibular gland are similar in appearance to those of the exorbital lacrimal gland, but with more extensive cellular processes that form a more or less continuous network with those of the adjacent cells. No MECs were observed on the terminal portion of the parotid gland where the cells appear to be lodged on the intercalated duct. The relative surface area covered by MECs per terminal portion was also found to vary significantly, being 24% in the lactating mammary, 17% in the exorbital lacrimal, 48% in the sublingual, and 25% in the submandibular glands. The findings are discussed in relation to the physical properties of secretions in different glands.
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    Cell & tissue research 207 (1980), S. 89-107 
    ISSN: 1432-0878
    Keywords: Rehydration ; Nongranular vasopressin ; Intercellular clefts ; Axoplasmic reticulum ; Ultrastructural immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The vasopressin system of the rat was examined in the course of the first 12 h of rehydration after prolonged thirst at light and electron microscopic levels and by use of the peroxidase anti-peroxidase (PAP) method. Light microscopically, the median eminence was the only part of the system that not only displayed distinct differences between animals of different rehydration times but also showed a characteristic pattern of immunohistochemical reactivity in its rostro-caudal distribution. Ultrastructurally, in the perikarya a maximal labeling of the rough endoplasmic reticulum was observed after 2 h of rehydration, whereas an extensive labeling of the enlarged Golgi zones was attained after 4 h of resupplying water. A labeling of the intercellular clefts in the basal glial labyrinth of the supraoptic nucleus (and to a lesser degree in the subependymal neuropil adjacent to the paraventricular nucleus) was increased 30 min after the onset of drinking, as compared with water-deprived animals; it decreased slightly after 12 h of rehydration. The filling of the swollen fibers by increasing amounts of labeled axoplasmic reticulum, evident in the nuclear areas already after 30 min of water supply, begins in the median eminence after 2 h of rehydration and is fully developed after 4 and 8 h. Corresponding results hold true for the neural lobe but are somewhat delayed in comparison to the findings in the median eminence. The discussion considers (i) synthesis and transport of nongranular vasopressin within the axoplasmic reticulum, and (ii) release not only from the neural lobe but also from the nuclear areas and from the fibers of the median eminence.
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    Cell & tissue research 263 (1991), S. 483-493 
    ISSN: 1432-0878
    Keywords: Mineralization in vitro ; Organoid culture ; Calvarial cells ; Matrix vesicles ; Cell necrosis ; Rat
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    Topics: Biology , Medicine
    Notes: Summary Various patterns of mineralization are found in the organism during fetal and postnatal development. Different findings and theories have been published in the literature with regard to the mechanisms of mineralization, many of which are controversely discussed. In the present study the different patterns of mineralization observed in the organoid culture system of fetal rat calvarial cells were investigated by electron microscopy. In organoid culture, calvarial cells grow and differentiate at high density, and deposition of osteoid and mineralization of the matrix occur to a very high extent. Different types of mineralization could be observed more or less simultaneously. It was found that hydroxyapatite crystals were formed at collagen fibrils as well as in the interfibrillar space. Mineralization was frequently seen in necrotic cells and cellular remnants as well as in extra-and intracellular vesicles. Addition of bone or dentin matrices or the artificial hydroxyapatite Interpore 200 to the cells caused an increased mineralization in the vicinity and on the surface of the matrices with and without participation of collagen. On previously formed mineralized nodules, an apposition of mineralizing material appeared due to matrix secretion by osteoblasts. It is concluded that initiation of mineralization occurs-at least in vitro-at every nucleation point under appropriate conditions. These mineralization foci enlarge by further apposition as well as by cellular secretion of a mineralizing matrix. Furthermore, cell necroses may liberate mineralizable vesicles. All these patterns of mineralization are the result of different activities of one cell type.
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  • 51
    ISSN: 1432-0878
    Keywords: Neuronal grafting ; Dopamine ; Nigrostriatal system ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Dissociated cell suspensions were prepared from the substantia nigra of 15–17 day-old rat embryos and grafted via an intraparenchymal injection into the depth of the neostriatum of adult recipient rats. The survival and fibre outgrowth of the dopamine-containing neurones in the implants were studied by fluorescence histochemistry, and the functional capacity of the grafts was monitored by repeated testing of the amphetamine-induced turning behaviour of the implanted rats. Before transplantation the target neostriatum of the recipient rats was denervated of its normal dopaminergic innervation by an injection of 6-hydroxydopamine into the ipsilateral nigrostriatal dopamine pathway. The completeness of the denervation was ascertained by measurement of the intensity of the amphetamine-induced turning response. After injection of the dissociated cells large numbers of dopamine-containing neurones were found in clusters at the site of injection as well as scattered in the apparently intact neostriatal tissue up to a distance of about 0.5 mm from the site of injection. Extensive dopamine-containing fibre networks had developed around the implant. These newly formed fibres, which were most abundant around the cell clusters at the injection site, extended in a loose network into large areas of the initially denervated caudate-putamen. In all animals with surviving dopamine neurones the amphetamine-induced turning response was reduced, and in the most extensively reinnervated cases even reversed, within 3–5 weeks after transplantation. This strongly suggests that the implanted dopamine neurones are capable of restoring dopaminergic neurotransmission in the denervated neostriatum, probably via reinnervation of the denervated neostriatal tissue. The use of dissociated brain tissue preparations thus permits reliable intraparenchymal grafting of neurones to plausibly any desired site within the central nervous system, and should open entirely new possibilities for investigation of neuronal growth dynamics and functional reconstruction of damaged brain circuits, perhaps even in brains of larger mammals.
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  • 52
    ISSN: 1432-0878
    Keywords: Pelvic plexus ; Autonomic ganglia ; Neuropeptides ; Tyrosine hydroxylase ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pelvic ganglia supply cholinergic and noradrenergic nerve pathways to many organs. Other possible transmitters are also present in these nerves, including peptides. Multiple labelling immunofluorescence techniques were used in this study of the male rat major pelvic ganglion (MPG) to examine: (1) the peptides present in noradrenergic (tyrosine hydroxylase (TH)-positive) and non-noradrenergic (putative cholinergic) neurons, and (2) the types of peptide-containing nerve fibres closely associated with these two groups of neurons. The distribution of the peptide galanin (GAL) within the MPG was also investigated. All of the TH-neurons contained neuropeptide Y (NPY), but none of the other tested peptides. However, many NPY neurons did not contain TH and may have been cholinergic. TH-negative neurons also displayed vasoactive intestinal peptide (VIP), enkephalin (ENK) or GAL. VIP and NPY formed the most common types of putative cholinergic pelvic neurons, but few cells contained both peptides. Many ENK neurons exhibited VIP, NPY or GAL. Varicose nerve terminals surrounding ganglion cells contained ENK, GAL, somatostatin (SOM) and cholecystokinin (CCK). These peptide-immunoreactive fibres were more often associated with the non-noradrenergic (putative cholinergic) than the noradrenergic neurons; two types (SOM and CCK) were preferentially associated with the non-noradrenergic NPY neurons. GAL was distributed throughout the MPG, in small neurons, scattered small, intensely fluorescent (SIF) cells, and both varicose and non-varicose nerve fibres. The nerve fibres were concentrated near the pelvic and penile nerves; most of the varicose fibres formed “baskets” surrounding individual GAL-negative somata.
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  • 53
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    Cell & tissue research 264 (1991), S. 555-561 
    ISSN: 1432-0878
    Keywords: Neuropeptides ; Colocalization ; Neuroepithelial bodies ; APUD cells ; Gene expression ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neuroendocrine cells of the lung, occurring singly or in clusters known as neuroepithelial bodies, contain a variety of biologically active compounds, including several neuropeptides. We have investigated the localization of calcitonin and calcitonin gene-related peptide (CGRP) within single and grouped neuroendocrine cells in the respiratory epithelium of rats by an immunohistochemical double-staining technique which uses specific antisera raised in heterogeneous animal species. Calcitonin- and CGRP-immunoreactivities were nearly totally co-localized in both single neuroendocrine cells and neuroepithelial bodies. CGRP-immunoreactivity was also present in neurons in the jugular, nodose and dorsal root ganglia. The calcitonin-immunoreactivity in neuroendocrine cells, as in thyroid parafollicular (C) cells, was abolished by preincubation of the anticalcitonin serum with synthetic calcitonin. The CGRP-immunoreactivity in neuroendocrine cells and in the neuronal cells was abolished by preincubation of anti-CGRP serum with synthetic CGRP. Thus, while the calcitonin gene is expressed exclusively or predominantly as either calcitonin or CGRP in all other tissues except thyroid C-cells, our results strongly suggest that both peptides are expressed in the rat bronchopulmonary neuroendocrine cells.
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  • 54
    ISSN: 1432-0878
    Keywords: Cardiac muscle cells ; Trabeculae carneae ; Fibrillar pattern ; Mouse ; Rat ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cardiac muscle fibers in the trabeculae carneae of mice, rats, and rabbits show a special arrangement of densely interwoven myofibrils. They cross at various angles; however, a preferred orientation of the fibrils cannot be discerned. It is suggested that due to this arrangement the myocytes of trabeculae are not able to contract to the same extent as ventricular myocytes, but thereby gain a high rigidity during contraction. Hence, they may play a principal role as “guiding ridges” for the flow of blood, thereby improving hemodynamics.
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  • 55
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    Cell & tissue research 209 (1980), S. 201-216 
    ISSN: 1432-0878
    Keywords: High pressure (2,100 bars) freezing ; Freeze-etching ; Nerve tissue ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Vitrification of biological specimens in liquid nitrogen can be achieved under high pressure (2,100 bars). This procedure obviates the use of aldehyde fixation and cryoprotection (glycerol). The present work demonstrates its applicability to the freeze-etching of mammalian brain tissue. Freeze-fracture replicas from rat cerebellar cortex and subfornical organ prepared by this method are compared to conventionally processed material using aldehyde fixation, glycerination and freezing with Freon. The formation of large ice crystals is prevented in tissue blocks up to 0.5 mm thick; deep etching is markedly enhanced. Cytoplasmic microstructures such as mitochondrial cristae, microtubules and microfilaments, are readily observable against a finely granulated cytosol matrix. An additional advantage is the combined application with freeze-substitution.
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  • 56
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    Cell & tissue research 206 (1980), S. 477-486 
    ISSN: 1432-0878
    Keywords: Synapse ; Synaptic cleft ; Aldehyde ; PTA technique ; Densitometry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Synaptic clefts of rat cerebral and cerebellar axodendritic spine synapses were studied after aldehyde-perfusion and subsequent immersion into osmic acid or after processing by the aldehyde-PTA technique. The threedimensional examination of aldehyde-perfused, osmic acid postfixed synapses revealed a double-layered intracleft lamina comparable in dimensions and position to the cleft density of non-osmicated, PTA-stained synapses. The relationship of this lamina to perisynaptic astroglial processes was pointed out. Densitometric analysis of the cleft area suggested the identity of the intracleft lamina of osmicated synapses with the cleft density of non-osmicated, PTA-stained synapses.
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  • 57
    ISSN: 1432-0878
    Keywords: Juxtaglomerular apparatus ; Sympathetic innervation ; Renin-angiotensin system ; Electron microscopy ; Fluorescence microscopy ; Tupaia belangeri ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary It has previously been reported that the primitive primate Tupaia belangeri develops a renal failure when exposed to psychosocial stress. In order to learn if this high susceptibility to stress of the Tupaia kidney can be correlated with morphological and functional parameters of the Juxtaglomerular apparatus (JGA) and the renin-angiotensin system, comparative experiments were performed on Tupaia and rat. Our results reveal an outstandingly high potency of the JGA and the renin-angiotensin system in Tupaia as evident from the following findings: The Tupaia JGA contains a great number of epithelioid cells abounding in renin granules (electron microscopy). The renin content of the Tupaia kidney is considerably higher than in the rat (radio-immunoassay). The sympathetic innervation of the kidney and especially of the JGA is abundant in Tupaia (fluorescence and electron microscopy). Catecholamine contents of the kidney and other organs are significantly higher in Tupaia than in rats (spectrophotofluorometry). Our results support the previously developed concept of a potent intrarenal neuroendocrine interaction at the JGA level favouring, under certain conditions of social stress, the development of acute renal failure in Tupaia belangeri.
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  • 58
    ISSN: 1432-0878
    Keywords: Cerebellum ; Purkinje axon ; Ultrastructure ; Axotomy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Transection of Purkinje cell axons in adult male rats made 1.5 mm or further from the cell body does not lead to the death of the neuron and results in compensatory structural alterations of the surviving axonal portions of the nerve cell. Near to, and at the emergence of recurrent collaterals of Purkinje cell axons, huge varicosities filled with filaments, granular material, lysosomes and mitochondria develop. Terminals of recurrent axon collaterals also exhibit different degrees of structural changes. Most striking of the morphological alterations is the regular presence of nematosomes in the hypertrophic axonal branches, especially in synaptic terminals. Since nematosomes were shown to contain RNA in other types of neurons, their presence in recurrent collaterals may indicate an enhanced synthetic activity in Purkinje axonal processes and endings after axotomy.
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  • 59
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    Cell & tissue research 213 (1980), S. 81-94 
    ISSN: 1432-0878
    Keywords: Interlamellar tight junctions ; Central myelin ; Myelogenesis ; Optic nerve ; Rat
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    Topics: Biology , Medicine
    Notes: Summary The process of myelination in the central nervous system (CNS) of the rat (optic nerve) was studied with the freeze-fracturing technique and ultrathin sectioning to obtain information on the developmental mechanisms of interlamellar tight junctions. Using a tilting cartridge for analysis of thin sections, it could be demonstrated that during the initial phase of wrapping a tight junction formation develops between the joining tips of the oligodendrocytic process. In tannic acid-stained samples these junctions appear as typical quintuple-layered membrane fusions, while in potassium permanganate-stained material membrane thickenings between the apposing glial tips are prevalent. The latter configuration represents the characteristic feature of the so-called radial component of central myelin. Using the freeze-fracturing technique, a biphasic mode of the myelinic tight junction assembly was detected. It is suggested that tight junctions represent a prerequisite of the myelination process.
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  • 60
    ISSN: 1432-0878
    Keywords: Salivary glands ; Innervation ; Immunohistochemistry ; Met5-enkephalin-Arg6-Gly7-Leu8 ; Tyrosine hydroxylase ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The localization of the proenkephalin A-derived octapeptide, Met5-enkephalin-Arg6-Gly7-Leu8 (MEAGL), was studied in the major salivary glands of Sprague-Dawley and Wistar rats with the indirect immunofluorescence method. MEAGL-immunoreactive nerve fibers were found around the acini, along intra-and interlobular salivary ducts and in close contact with blood vessels. In the parotid and submandibular glands tyrosine hydroxylase (TH) immunoreactivity was observed in nerve fibers around the acini, in association with intra- and interlobular salivary ducts and around blood vessels, while in the sublingual gland TH-immunoreactive nerve fibers were only seen around blood vessels. Parasympathetic neurons in submandibular ganglia contained MEAGL immunoreactivity. Moderate TH immunoreactivity was seen in some neurons of the submandibular ganglia. A subpopulation of sympathetic principal neurons in the superior cervical ganglion were immunoreactive for both MEAGL and TH. In the trigeminal ganglion, no MEAGL-immunoreactive sensory neurons or nerve fibers were observed. Superior cervical ganglionectomies resulted in a complete disappearance of TH-immunoreactive nerve fibers, while MEAGL-immunoreative nerve fibers were still present in the glands. The presence of MEAGL immunoreactivity in neurons of both sympathetic superior cervical ganglia and parasympathetic submandibular ganglia and the results of superior cervical ganglionectomies suggest, that MEAGL-immunoreactive nerve fibers in the major salivary glands of the rat have both sympathetic and parasympathetic origin.
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  • 61
    ISSN: 1432-0878
    Keywords: Adrenal autotransplants ; Sodium restriction ; Mineralocorticoid hormones ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Regenerated adrenocortical nodules were obtained by implanting fragments of the capsular tissue of excised adrenal glands into the musculus gracilis of rats (Belloni et al. 1990). Five months after the operation, operated rats showed a normal basal blood level of corticosterone, but a very low concentration of circulating aldosterone associated with a slightly increased plasma renin activity (PRA). Regenerated nodules were well encapsulated and some septa extended into the parenchyma from the connective-tissue capsule. The majority of parenchymal cells were similar to those of the zonae fasciculata and reticularis of the normal adrenal gland, while zona glomerulosa-like cells were exclusively located around septa (juxta-septal zone; JZ). In vitro studies demonstrated that nodules were functioning as far as glucocorticoid production was concerned, while mineralocorticoid yield was very low. Prolonged sodium restriction significantly increased PRA and plasma aldosterone concentration, and provoked a marked hypertrophy of JZ, which was due to increases in both the number and average volume of JZ cells. Accordingly, the in vitro basal production of aldosterone and other 18-hydroxylated steroids was notably enhanced. The plasma level of corticosterone, as well as zona fasciculata/reticularis-like cells and in vitro production of glucocorticoids by regenerated nodules were not affected. These findings, indicating that autotransplanted adrenocortical nodules respond to a prolonged sodium restriction similar to the normal adrenal glands, suggest that the relative deficit in mineralocorticoid production is not due to an intrinsic defect of the zona glomerulosa-like JZ, but is probably caused by the impairment of its adequate stimulation under basal conditions. The hypothesis is advanced that the lack of splanchnic nerve supply and chromaffin medullary tissue in regenerated nodules may be the cause of such an impairment.
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  • 62
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    Molecular genetics and genomics 230 (1991), S. 241-250 
    ISSN: 1617-4623
    Keywords: Yeast ; Saccharomyces cerevisiae ; Adenylyl cyclase ; CDC25 ; RAS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The TFS1 gene of Saccharomyces cerevisiae is a dosage-dependent suppressor of cdc25 mutations. Overexpression of TFS1 does not alleviate defects of temperature-sensitive adenylyl cyclase (cdc35) or ras2 disruption mutations. The ability of TFS1 to suppress cdc25 is allele specific: the temperature-sensitive cdc25-1 mutation is suppressed efficiently but the cdc25-5 mutation and two disruption mutations are only partially suppressed. TFS1 maps to a previously undefined locus on chromosome XII between RDN1 and CDC42. The DNA sequence of TFS1 contains a single long open reading frame encoding a 219 amino acid polypeptide that is similar in sequence to two mammalian brain proteins. Insertion and deletion mutations in TFS1 are haploviable, indicating that TFS1 is not essential for growth.
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  • 63
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    Molecular genetics and genomics 226 (1991), S. 97-106 
    ISSN: 1617-4623
    Keywords: Yeast ; Linear plasmid ; Saccharomyces kluyveri ; Kluyveromyces lactis ; Killer plasmid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have determined the complete nucleotide sequence of the linear DNA plasmid, pSKL, isolated from Saccharomyces kluyveri. Sequence analysis showed that pSKL has a high (A+T) content of 71.7%, and that there are 10 open reading frames (ORFs) larger than 250 nucleotides. All 10 ORFs were shown to be transcribed in S. kluyveri cells by S1 nuclease mapping analysis. The localization of ORFs, direction of transcription, and the predicted amino acid sequences of each ORF were quite similar to that of pGKL2, one of the killer plasmids found in Kluyveromyces lactis. The amino acid sequences of the largest two ORFs (ORF2 and ORF6) have homology with several DNA polymerases and RNA polymerases, respectively.
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  • 64
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    Molecular genetics and genomics 226 (1991), S. 145-153 
    ISSN: 1617-4623
    Keywords: Retrotransposons ; Reverse transcription ; Ty elements ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transposition of the yeast transposable element, Ty, has been shown to require a reverse transcription process. By analysing the extrachromosomal Tyspecific nucleic acid molecules associated with overproduced Ty virus-like particles (Ty-VLPs), we identified several reverse transcribed cDNA strands. Most of them resemble the characteristic intermediates of the reverse transcription process described for authentic retroviruses: a (−) strong-stop DNA strand covalently bound to an RNA primer, two elongated (−) strands with one or two long terminal repeat (LTR) sequences and a (+) strong-stop DNA. Surprisingly, complete (+) strands and full-length linear duplex Ty DNA could not be detected. The structural features of two additional (÷) strands may indicate some differences between the mechanisms of (+) strand synthesis in Ty and other retrotransposons or retroviruses.
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  • 65
    ISSN: 1617-4623
    Keywords: Yeast ; Arginine ; Sequence ; Regulation ; Control region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Saccharomyces cerevisiae, the ARG5,6 gene encodes acetylglutamyl-P reductase and acetylglutamate kinase, two arginine anabolic enzymes which are localized in the mitochondria. The synthesis of both enzymes is co-ordinately controlled by arginine and by three regulatory proteins (ARGRI, ARGRII, and ARGRIII). The ARG5,6 gene was cloned by complementation of an arg5 mutant strain. A subclone containing an EcoRI fragment of about 3.2 kb which complements the arginine requirement was sequenced. This 3163 by sequence contains only one long open reading frame of 2589 nucleotides encoding a protein of 863 amino acids. The size of this protein is in agreement with the length of the unique transcript determined by Northern hybridization. The measurements of ARG5,6 mRNA under various regulatory conditions show no correlation with the enzyme levels. As in other arginine biosynthetic and catabolic genes, the regulation by arginine through the three ARGR proteins thus involves a post-transcriptional control mechanism. By in vitro mutagenesis we created point mutations and deletions in the 5′ non-coding region of the ARG5,6 gene which allowed us to define the primary target of ARGR control. Specific regulation involves two regions: one located between the putative TATA element and the transcriptional initiation site and the second between this site and the first ATG.
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  • 66
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    Molecular genetics and genomics 229 (1991), S. 413-420 
    ISSN: 1617-4623
    Keywords: SCO1 ; Cytochrome oxidase ; Membrane protein ; Mitochondria ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The SCO1 gene of Saccharomyces cerevisiae encodes a 30 kDa protein which is specifically required for a post-translational step in the accumulation of subunits 1 and 2 of cytochrome c oxidase (COXI and COXII). Antibodies directed against a β-Gal::SCO1 fusion protein detect SCO1 in the mitochondrial fraction of yeast cells. The SCO1 protein is an integral membrane protein as shown by its resistance to alkaline extraction and by its solubilization properties upon treatment with detergents. Based on the results obtained by isopycnic sucrose gradient centrifugation and by digitonin treatment of mitochondria, SCO1 is a component of the inner mitochondrial membrane. Membrane localization is mediated by a stretch of 17 hydrophobic amino acids in the amino-terminal region of the protein. A truncated SCO1 derivative lacking this segment, is no longer bound to the membrane and simultaneously loses its biological function. The observation that membrane localization of SCO1 is affected in mitochondria of a rho 0 strain, hints at the possible involvement of mitochondrially coded components in ensuring proper membrane insertion.
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  • 67
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    Molecular genetics and genomics 225 (1991), S. 363-368 
    ISSN: 1617-4623
    Keywords: Yeast ; Metallothionein gene ; Cadmium resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 3.3 kb fragment of yeast genomic DNA was isolated by screening a genomic library constructed in the high copy number 2 micron plasmid YEp351 vector for clones capable of enhancing the degree of resistance of Saccharomyces cerevisiae strain MW3070-8B to cadmium. The insert contained two complete copies of the CUP1 gene open reading frame (183 bp), including the upstream promoter sequences (450 bp) with two conserved metal responsive cis-acting elements. Northern analysis showed that addition of cadmium (0.02 μM) or copper (50 μM) to overnight liquid cultures of yeast induced expression of CUP1 transcripts from both chromosomal and plasmid-borne gene copies. The cloned 3.3 kb DNA in a high copy number plasmid restored copper resistance to the sensitive strain LS70-313Δ, deleted for the CUP1 gene (cup1Δ), but failed to restore cadmium resistance. Thus, CUP1 gene expression in yeast appears to be influenced differently by cadmium and copper ions. Resistance to heavy metal poisoning resulted from enhanced gene product levels attributable to amplification of the CUP1 gene as well as to increased transcriptions. Two distinct gene product levels mediate cadmium and copper resistance; a higher gene product level was required to confer cadmium resistance.
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  • 68
    ISSN: 1617-4623
    Keywords: Meiosis ; Sporulation ; Northern hybridization ; Regulatory circuit ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The SGA1 gene encoding glucoamylase is specifically expressed late in meiotic development of the yeast Saccharomyces cerevisiae. We found that accumulation of both enzyme activity and transcripts was regulated negatively by both nutritional signals and a haploid-specific negative regulator gene of meiosis, RME1, and positively by the inducer genes for meiosis, IME1 and IME2. To study the role of sequences upstream of the SGA1 gene in its expression and regulation, we generated internal deletions in the 5′ non-coding region of the gene and chimeric genes with portions of the upstream sequence inserted into a reporter gene. By analyzing the expression of these genes, we have identified both a 19 by upstream activation sequence (UAS) and a 49 by negatively regulating element (NRE). The UAS activated transcription with no requirement for heterozygosity at the mating-type locus, but this activation was still under negative control by nutrients. The NRE showed no UAS-like activity but conferred IME2-dependent (or meiosis-specific) expression on a heterologous promoter. These results suggest that meiosis-specific expression of the SGA1 gene is established by a regulatory hierarchy including positive and negative factors, the actions of which are mediated through the two separate upstream regulatory elements, UAS and NRE, respectively. Also, that two independently acting cascades exist for the regulation of SGA1 expression: one transduces both the mating-type and nutritional signals and includes the IME2 product, which acts to relieve the repression through NRE ; and another transduces only the nutritional signal independently of the above pathway and inhibits positive factors acting on UAS.
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  • 69
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    Molecular genetics and genomics 227 (1991), S. 127-136 
    ISSN: 1617-4623
    Keywords: Yeast ; Killer toxin ; Immunity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A cDNA copy of the M2 dsRNA encoding the K2 killer toxin ofSaccharomyces cerevisiae was expressed in yeast using the yeastADH1 promoter. This construct produced K2-specific killing and immunity functions. Efficient K2-specific killing was dependent on the action of the KEX2 endopeptidase and the KEX1 carboxypeptidase, while K2-specific immunity was independent of these proteases. Comparison of the K2 toxin sequence with that of the K1 toxin sequence shows that although they share a common processing pathway and are both encoded by cytoplasmic dsRNAs of similar basic structure, the two toxins are very different at the primary sequence level. Site-specific mutagenesis of the cDNA gene establishes that one of the two potential KEX2 cleavage sites is critical for toxin action but not for immunity. Immunity was reduced by an insertion of two amino acids in the hydrophobic amino-terminal region which left toxin activity intact, indicating an independence of toxin action and immunity.
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  • 70
    ISSN: 1617-4623
    Keywords: Yeast ; Mitochondria ; Frameshift ; Suppression ; Restriction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The +1 frameshift mutation, M5631, which is located in the gene (oxi1) for cytochrome c oxidase II (COXII) of the yeast mitochondrial genome, is suppressed spontaneously to a remarkably high extent (20%–30%). The full-length wild-type COXII produced as a result of suppression allows the mutant strain to grow with a “leaky” phenotype on non-fermentable medium. In order to elucidate the factors and interactions involved in this translational suppression, the strain with the frameshift mutation was mutated by MnCl2 treatment and a large number of mutants showing restriction of the suppression were isolated. Of 20 mutants exhibiting a strong, restricted, respiration-deficient (RD) phenotype, 6 were identified as having mutations in the mitochondrial genome. Furthermore, genetic analyses mapped one mutation to the vicinity of the gene for tRNAPro and two others to a region of the tRNA cluster where two-thirds of all mitochondrial tRNA genes are encoded. The degree of restriction of the spontaneous frameshift suppression was characterized at the translational level by in vivo 35S-labeling of the mitochondrial translational products and immunoblotting. These results showed that in some of these mutant strains the frameshift suppression product is synthesized to the same extent as in the leaky parent strain. It is suggested that more than one +1 frame-shifted product is made as a result of suppression in these strains: one is as functional as the wild-type COXII, the other(s) is (are) non-functional and prevent leaky growth on non-fermentable medium. A possible mechanism for this heterogenous frameshift suppression is discussed.
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  • 71
    ISSN: 1617-4623
    Keywords: SNF2 sequence ; Transcriptional regulator ; Gene expression ; Glucoamylase ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have cloned and sequenced the GAM1 gene which is required for transcription of the STA1 gene encoding an extracellular glucoamylase in Saccharomyces cerevisiae var. diastaticus. Complementation tests indicated that GAM1 is the same gene as SNF2 which is required for derepression of the SUC2 gene encoding invertase. Accumulation of SNF2 RNA was not regulated by the GAM2 and GAM3 genes which are also required for STA1 expression. The SNF2 gene was predicted to encode a 194 kDa highly charged protein with a glutamine-rich tract. A bifunctional SNF2-lacZ fusion protein was shown by immunofluorescence microscopy to be localized to the nucleus, suggesting that the SNF2 protein is located in the nucleus.
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  • 72
    ISSN: 1617-4623
    Keywords: Protein kinase ; Yeast ; CDC28 ; Cell cycle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A novel protein kinase homologue (KNS1) has been identified in Saccharomyces cerevisiae. KNS1 contains an open reading frame of 720 codons. The carboxy-terminal portion of the predicted protein sequence is similar to that of many other protein kinases, exhibiting 36% identity to the cdc2 gene product of Schizosaccharomyces pombe and 34% identity to the CDC28 gene product of S. cerevisiae. Deletion mutations were constructed in the KNS1 gene. kns1 mutants grow at the same rate as wild-type cells using several different carbon sources. They mate at normal efficiencies, and they sporulate successfully. No defects were found in entry into or exit from stationary phase. Thus, the KNS1 gene is not essential for cell growth and a variety of other cellular processes in yeast.
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    Molecular genetics and genomics 229 (1991), S. 353-356 
    ISSN: 1617-4623
    Keywords: DNA polymerase ; Gene conversion ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Saccharomyces cerevisiae, three different DNA polymerase complexes, POLI, POLII and POLIII, are known to be involved in DNA replication. The catalytic subunit of POLIII is encoded by the essential CDC2 gene. The existence of different thermosensitive non-complementing mutants of CDC2 offers the possibility of using a genetic approach to investigate the involvement of POLIII in induced gene conversion. When cdc2 heteroallelic cells were irradiated and incubated under restrictive conditions, almost no induction of thermoresistant cells could be detected, suggesting an essential role for POLIII in mitotic gene conversion events.
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  • 74
    ISSN: 1617-4623
    Keywords: Translational activation ; Cytochrome b ; Mitochondria ; Yeast ; CRS1 ; CBS2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The products of the nuclear genes CBS1 and CBS2 are both required for translational activation of mitochondrial apocytochrome b in yeast. We report the intramitochondrial localization of both proteins by use of specific antisera. Based on its solubilization properties the CBS1 protein is presumed to be a component of the mitochondrial membrane; the detergent concentrations needed to release CBS1 from mitochondria are almost the same as for cytochrome c 1. In contrast, CBS2 behaves like a soluble protein, with some characteristics of a membrane-associated protein. A model is presented for translational activation of cytochrome b, which might also be applicable to translational regulation of other mitochondrial genes.
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  • 75
    ISSN: 1617-4623
    Keywords: Yeast ; Transcription ; a- and α-specific genes ; MCM1 ; STE12
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have examined the relative contributions of MCM1 and STE12 to the transcription of the a-specific STE2 gene by using a 367 by fragment from the STE2 5′-noncoding region to drive expression of a reporter lacZ gene. Mutation of the MCM1 binding site destroyed MCM1 · α2-mediated repression in α cells and dramatically reduced expression in a cells. The residual expression was highly stimulated by exposure of cells to pheromone. Likewise, the loss of STE12 function reduced lacZ expression driven by the wild-type STE2 fragment. In the absence of both MCM1 and STE12 functions, no residual expression was observed. Thus, the STE2 fragment appears to contain two distinct upstream activation sequences (UASs), one that is responsible for the majority of expression in cells not stimulated by pheromone, and one that is responsible for increased expression upon pheromone stimulation. In further support of this idea, a chemically synthesized version of the STE2MCM1 binding site had UAS activity, but the activity was neither stimulated by pheromone nor reduced in ste12 mutants. Although transcription of aspecific genes also requires both MCM1 and STE12, these genes differ from a-specific genes in that they have a single, MCM1-dependent UAS system. The activity of the minimal 26 by UAS from the α-specific STE3 gene was both stimulated by pheromone and reduced in ste12 mutants. These data suggest that at α-specific genes STE12 and MCM1 exert their effects through a single UAS.
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  • 76
    ISSN: 1617-4623
    Keywords: Mitochondria ; Yeast ; Protein targeting ; PET2858 ; Inner membrane protease 1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nuclear yeast mutant pet ts2858 is defective in the removal of pre-sequences from the mitochondrially encoded cytochrome oxidase subunit II (COXII) and the processing intermediate of cytochrome b 2 (Cytb 2), a nuclear gene product. In order to identify the genetic lesion in this mutant we have cloned and characterized a DNA region which complements the pet ts2858 mutation. The DNA sequence revealed three open reading frames, one of which is responsible for the complementation. A 570 by reading frame represents the structural gene PET2858, as demonstrated by in vitro mutagenesis, gene expression from a foreign promoter, and allelism tests. PET2858 encodes a 21.4 kDa protein, which is essential for growth on non-fermentable carbon sources and for the proteolytic processing of COXII and the Cytb 2 intermediate. When the N-terminus of the PET2858 protein is fused to a reporter protein, the resulting hybrid molecule is imported into mitochondria. Interestingly, the N-terminal half of the deduced PET2858 protein exhibits 30.7% amino acid identity to the leader peptidase of Escherichia coli. These results suggest that PET2858 codes for a mitochondrial inner membrane protease (IMP1) or at least a subunit of it. This protease is involved in protein processing and export from the mitochondrial matrix.
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  • 77
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    Antonie van Leeuwenhoek 59 (1991), S. 125-127 
    ISSN: 1572-9699
    Keywords: Taxonomy ; Williopsis Salicorniae ; Yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four strains of an undescribed species of the genus Williopsis were isolated from brackish water. A description of the new species, Williopsis salicorniae (type strain, CBS 8071, NRRL Y-12834), is given.
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  • 78
    ISSN: 1432-136X
    Keywords: Thyroidectomy ; Sucrase ; β-Galactosidases ; Aminopeptidase ; Messenger RNA ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of long-term starvation on the activities of sucrase, lactase, and aminopeptidase, and on their respective mRNA were determined in the small intestine of thyroidectomized and sham-operated adult rats. Thyroidectomy reduced the protein loss at the level of the intestinal brush border membranes during starvation. Prolonged fasting caused a significant decrease in sucrase activity, but thyroidectomy partly prevented this effect. However, the amount of the corresponding mRNA dropped during long term starvation without incidence of thyroidectomy. Lactase activity in the brush border membranes was increased by starvation, and thyroidectomy caused a further elevation of the enzyme activity. Simultaneously, lactase mRNA content rose only slightly compared to the enzyme activity. Amnopeptidase activity and mRNA content decreased during starvation and thyroidectomy did not prevent this process. These results indicate that intestinal hydrolases respond non-coordinately to long-term food deprivation. In addition, the thyroid status of the animals has a direct influence on the adaptation of several brush border hydrolases to starvation. This suggests that the drop in plasma thyroid hormones during fasting allows a better maintenance of protein content and of hydrolase activities in the brush border membranes of the small intestine. These adaptive processes seemed to be partly controlled at a post-transcriptional level.
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  • 79
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    Cell & tissue research 205 (1980), S. 327-331 
    ISSN: 1432-0878
    Keywords: Somatostatin ; Cortical cells and fibers ; Immunohistochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using light microscopic immunohistochemistry, somatostatinpositive structures were observed in the cortex of the rat. These structures, including cells and fibers, are widely distributed in all cortical laminae and are also found in the basal ganglia. The positive results were obtained exclusively in two groups of animals sacrificed during two different months of two subsequent years. The reason for this variability in the immunocytochemical stainability of cortical structures remains enigmatic.
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  • 80
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    Cell & tissue research 205 (1980), S. 445-451 
    ISSN: 1432-0878
    Keywords: Exocrine pancreas ; Rat ; Architecture
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    Topics: Biology , Medicine
    Notes: Summary The architecture of the pancreas was revealed by retrograde injection of the pancreatic ductal system of normal rats with a silicone rubber compound, and subsequent study of the preparation by light microscopy and scanning electron microscopy. The injected material became associated with both ducts and “acinar” areas. Examination of these specimens suggests that the arrangement of the exocrine pancreas is that of a complexly curving and branching system of tubules which anastomose and end blindly. This architecture, which is not that of a true acinar gland, provides a rational basis for the understanding of the simple dedifferentiative changes that accompany pancreatic carcinogenesis, and which have been generally interpreted as representing ductular proliferation.
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  • 81
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    Cell & tissue research 205 (1980), S. 453-471 
    ISSN: 1432-0878
    Keywords: Vasopressin system ; Postnatal development ; Ultrastructural immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present ultrastructural results indicate that, in the rat, the vasopressin-synthesizing perikarya of the supraoptic nucleus (NSO) attain a certain degree of maturity earlier than those of the paraventricular nucleus (NPV). In the neonate rat, the stainability of the nuclear areas is very weak; in the perikarya of the NSO a few labeled granules can be found, whereas the perikarya of the NPV often display only a labeled Golgi area, the cytoplasm being devoid of granules. At the end of the first (NSO) and the second (NPV) postnatal weeks, the filling of the neurosecretory granules with vasopressin is inhomogeneous with irregular spots of reaction product distributed on the granules. This feature is less obvious during the following week and has nearly disappeared after the third and fourth postnatal weeks. Already in the neonate two types of vasopressin-positive fibers are observed in the median eminence, characterized by the different diameters of their granules and by their typical location in the internal and the external pericapillary contact zone. Especially in one and two week-old animals, in the internal zone of the median eminence and, to a lesser degree in the neural lobe, the immunocytochemical reaction product is deposited on an axonal tubular network. Judging from the presence of very few vasopressin-negative fibers in the neural lobe of the neonate, the development of the oxytocin system appears to be delayed. A characteristic relationship between pituicytes and the neurosecretory fibers can be observed during the first two postnatal weeks. After the third postnatal week the immunocytochemical features of the vasopressin system correspond approximately to that in adult rats.
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  • 82
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    Cell & tissue research 206 (1980), S. 139-143 
    ISSN: 1432-0878
    Keywords: Pituitary cleft ; Scanning electron microscopy ; Cell surface changes ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Scanning electron microscopy of the lining of the pituitary cleft was carried out in normal, lactating, castrated, adrenalectomized, and cyproterone-treated adult rats. Four cell types could be differentiated in the posterior wall in control and experimental animals: (1) cells with a smooth surface, (2) cells with microvilli located at the cellular borders, (3) ciliated cells, and (4) cells with evenly distributed microvilli. The anterior wall showed mainly cells with few microvilli located at their margins, and clusters of ciliated cells. In normal, and more frequently in experimental animals, the anterior wall showed shriveled cells, and variously sized cavities. Colloid appeared either as a network of finely granular material or as compact bodies adhering to the epithelial surface. These observations suggest that a compact component of the colloid is derived at least in part from degraded cells.
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  • 83
    ISSN: 1432-0878
    Keywords: AVT ; LHRH ; α-MSH ; Somatostatin ; Pineal Gland ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Resumé En utilisant des anticorps contre l'AVT, l'α-MSH, le LHRH et la somatostatine, des cellules épiphysaires du Rat ont été immunocytochimiquement colorées. Tous ces anticorps colorent les mêmes cellules. Ces cellules réagissent également quand un anticorps est utilisé contre la fraction épiphysaire UMO5R, fraction qui est douée de propriétés antigonadotropiques in vivo. Il a également été montré que le nombre des cellules immunoréactives était plus important dans la pinéale du jeune rat que dans celle de l'adulte. La comparaison des résultats obtenus avec différents anticorps et l'étude des propriétés de ces anticorps aprés absorption sur différents peptides ou sur différentes fractions épiphysaires, a permis de conclure que les réactions obtenues dans la pinéale du rat n'étaient que la conséquence d'une réaction croisée de ces anticorps avec une/des substance(s) inconnue(s) synthétisée(s) par la pinéale elle-même. La nature endocrine possible de cette substance qui serait chimiquement apparenté aux fractions épiphysaires Mouton UMO5R et Prot. 4, est discutée. Drs. B.L. Baker (Ann Arbor, Mich., USA), M.P. Dubois (Nouzilly, France), J. De Mey (Beerse, Belgium), J.D. Fernstrom (Cambridge, Mass., USA.), H. Goos (Utrecht, The Netherlands), B. Kerdelhué (Gif-sur-Yvette, France) and A.G.E. Pearse (London, U.K.) are also acknowledged for their gifts of various antibodies
    Notes: Summary Using antibodies against AVT, α-MSH, LHRH and somatostatin, immunoreactive cells were detected in the rat pineal gland. All of these antibodies stain the same cells, which also react immunocytochemically when an antibody against the UMO5R sheep pineal fraction, a fraction that presents antigonadotropic properties in vivo, is used. Relatively more immunoreactive cells are present in the pineals of young rats than in the pineals of adult animals. Comparison of the results obtained with different potent antibodies against each of the peptides, and a study of the staining properties of the antibodies in the pineal after solid phase adsorption to different peptides or to different sheep pineal fractions, led to the proposal that the immunoreactivity found in the rat pineal is not due to the presence of AVT, α-MSH, LHRH or somatostatin, but to a cross-reaction of each of these antibodies with (an) unidentified compound(s). This compound is synthetized in the pineal gland, as was demonstrated using cultured pineals. The UMO5R and the Prot. 4 fractions of the sheep pineal seem to be chemically related to this unknown compound, the possible endocrine nature of which is discussed.
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  • 84
    ISSN: 1432-0878
    Keywords: Sympathetic nerves ; Synaptic vesicles ; Noradrenaline ; Serotonin ; Pineal gland ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The pineal gland of the rat receives a rich nervous supply originating from the superior cervical ganglia. These fibers contain serotonin in addition to their neurotransmitter, noradrenaline. Cytochemical studies at the ultrastructural level have shown that both amines are present in the cores of the granular vesicles that are characteristic of these nerves. It is presently shown that the bilateral electrical stimulation of the preganglionic fibers innervating the ganglia markedly reduces the number of small sites reacting cytochemically for both noradrenaline and serotonin, these sites corresponding to the cores of small granular vesicles, while the larger reactive sites (cores of large vesicles) remain unaltered. The vesicles are retained in nerve terminals after stimulation, as observed in conventionally processed tissues, although with altered sizes and shapes. Apart from these cytochemical and structural changes, nerve stimulation also reduces the endogenous noradrenaline content of the pineal gland. Thus, both noradrenaline and serotonin are released from their storage sites in pineal sympathetic nerves after electrical stimulation in vivo. This suggests the possibility that several substances with presumed transmitter or modulatory functions might be simultaneously released by nerve impulses from a given nerve terminal.
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  • 85
    ISSN: 1432-0878
    Keywords: Islet of Langerhans ; Aging ; Insulin-secreting cells ; Organ culture ; Electron microscopy ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The B-cells of the endocrine pancreas constitute an adequate model for in vitro study of the aging process in highly differentiated cells. In the present study, collagenase-isolated islets of Langerhans from young and senescent rats were cultured up to 28 days. The response of the B-cells to the stimulatory conditions of the culture medium involved the nucleus, ribosomes, endoplasmic reticulum, Golgi apparatus, and secretory granules. Correlated data from light microscopy, electron microscopy, and insulin radioimmunoassay show that the differentiation and function of senescent B-cells are maintained in culture, as it has been proven for the B-cells of younger animals. On the other hand, signs of cytological deficiency not directly concerned with the specific function of B-cells were observed: abnormal mitochondria and lysosomes are more numerous in the senescent B-cells. The proliferative capacity of the B-cells of aged rats is reduced.
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  • 86
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    Cell & tissue research 207 (1980), S. 479-489 
    ISSN: 1432-0878
    Keywords: Horseradish peroxidase ; Primary afferent neurons ; Axonal transport ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The dynamics of horseradish peroxidase (HRP) transport in primary sensory neurons were studied in rats by demonstration of the reaction product in spinal nerves, spinal ganglia, dorsal roots and in the spinal cord at different survival times after application of the enzyme to the transected sciatic nerve and to the spinal cord. Using tetramethylbenzidine as the chromogen according to Mesulam (1978), transganglionic transport of HRP was shown in both the disto-proximal direction after peripheral application, and proximo-distal direction after central application. Significant differences in staining intensity between the central and peripheral processes of primary sensory neurons were found after all survival times used in this study. After peripheral application the number of labeled axons and the staining intensity were higher in spinal nerves than in dorsal roots; an inverse situation occurred after central application. These differences as well as the time sequences in staining of different parts of primary sensory neurons suggest that HRP applied to a peripheral nerve and to the spinal cord, respectively, enters the perikarya of spinal ganglion cells in any case before continuing its movement in a cellulifugal direction. Lysosomal degradation of the major portion of the applied HRP is supposed. However, in the post-perikaryal portion of a considerable number of neurons HRP-transport still occurs to a varying extent, thus resulting in labeling of nerve endings. In some neurons a post-perikaryal transport could not be detected light microscopically. The transport rates differ: the calculated transport rate of disto-proximal, cellulipetal movement in the fastest transporting neurons was 7.5 mm/h, that of the disto-proximal cellulifugal movement 2.5 to 3 mm/h.
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    Cell & tissue research 208 (1980), S. 253-259 
    ISSN: 1432-0878
    Keywords: Villus ; Caecum ; Postnatal development ; Rat ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The villi of the caecal mucosa in postnatal rats were studied using both scanning electron and light microscopy. On the day of birth, numerous villi of various sizes and shapes were present on the caecal mucosa. After the 5th day, the villi decreased very rapidly in length and in number. A strong constriction was observed at the basal region of the caecal villi. During postnatal days 5 ∼ 9 the villi probably separated and disappeared from the caecal mucosa. No villi were observed in rats that were over 10 days of age.
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    Cell & tissue research 209 (1980), S. 225-238 
    ISSN: 1432-0878
    Keywords: Tanycytes ; Median eminence ; Electron microscopy ; Rat ; Serum LH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The transport of hormones from the cerebrospinal fluid to the adenohypophysis by the tanycytes of the median eminence was examined in male rats. Electron microscopy revealed that all ependymal cells including the tanycytes disappear or degenerate in rats subjected to electric cauterization of the ependymal layer lining the third ventricle. However, the granular axons in the palisade layer of the median eminence remain intact. In rats subjected to electric lesion, no significant change was found in either the serum-LH level or in the weight of the adenohypophysis, testes, adrenal and thyroid glands. It is concluded that the tanycytes do not participate in the hypothalamic regulation of hypophysial function.
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    Cell & tissue research 209 (1980), S. 499-503 
    ISSN: 1432-0878
    Keywords: LHRH perikarya ; Aging ; Rat
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary The LHRH-synthesizing neuron system was studied in young proestrous and old female rats, and in aged ovariectomized or reserpine-treated females. The medial preoptic area and septal region of old animals contains more LHRH positive perikarya compared to that of young proestrous rats. Reserpine treatment moderately increases the number of immunostainable LHRH cells, while ovariectomy is ineffective in this respect.
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  • 90
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    Cell & tissue research 210 (1980), S. 33-45 
    ISSN: 1432-0878
    Keywords: Luliberin (LRF)-terminals ; Somatostatin-terminals ; Subfornical organ ; Neurohemal regions ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary With the aid of light- and electron- microscopic immunocytochemistry, somatostatin- and luliberin (LRF)-positive fibers can be demonstrated in the rat subfornical organ (SFO). Each of the neurohormones has a specific location: LRF in the lateral parts of the organ, and somatostatin in the center of the posterior zone. Common to both neurohormone-containing fibers is the pattern in which they reach the organ as well as the fact that their terminals are located in the perivascular spaces of fenestrated vessels, i.e., within the limited neurohemal regions of the organ. Since injection of India ink of different colors demonstrates that the capillary bed of the SFO is connected with the central capillaries of the choroid plexus, the question arises as to whether the neurohormones released in the area of the SFO influence the choroid plexus.
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  • 91
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    Cell & tissue research 210 (1980), S. 283-294 
    ISSN: 1432-0878
    Keywords: Deep pineal ; Pineal complex ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The results presented here reveal that in adult Sprague-Dawley and Wistar rats the pineal gland represents a complex rather than a single organ. Regularly one can distinguish (i) pineal tissue in the intercommissural region as a deep pineal, (ii) a superficial pineal, which represents the major part of the pineal complex, and (iii) nearly always a parenchymal stalk of variable length. The volume of the deep pineal with the adjacent parenchymal stalk exhibits great interindividual variation. It amounts to 127±39×105 μm3 (mean ±standard deviation). The histological appearance of the deep and superficial pineal tissue is fairly similar. The intrinsic cells of the deep and superficial pineal differ in nuances only. Karyometry reveals that the nuclear volumes of the intrinsic cells of the deep pineal are very variable ranging from 90–450 μm3, with a mean value of 207 μm3. The changes over a period of 24 h reach statistical significance.
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  • 92
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    Cell & tissue research 210 (1980), S. 333-337 
    ISSN: 1432-0878
    Keywords: Zona glomerulosa ; Angiotensin II ; Mitochondria ; Stereology ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of a chronic treatment with angiotensin II (up to 15 consecutive days) on the mitochondria of the rat zona glomerulosa cells were investigated by electron microscopic and stereological methods. Angiotensin induced a significant increase in the volume of the mitochondrial compartment. Up to the 3rd day of treatment this was due only to the hypertrophy of the organelles, and from the 3rd to the 15th day exclusively to mitochondrial proliferation. The hypothesis that angiotensin controls the growth and proliferation of rat zona glomerulosa mitochondria is discussed.
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  • 93
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    Cell & tissue research 211 (1980), S. 175-177 
    ISSN: 1432-0878
    Keywords: Parietal cell ; Stomach ; Circadian rhythm ; Morphometry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Gastric parietal cells of rats maintained under standardized conditions and fed ad libitum were examined by electron microscopy at 6 time points of the 24-h day. Morphometric determinations were made on 4 cell characteristics. The volume density of secretory canaliculi was maximal at the mid-dark sampling point and decreased during the light phase; a secondary peak was seen 1 h before the onset of darkness. The surface density of microvesicles and RER fluctuated inversely with the pattern displayed by secretory canaliculi. The number of multivesicular bodies per cytoplasmic area exhibited a single peak, 1 h after the onset of darkness. It was further noted that parietal cells in the necks and bases of glands differed morphologically and that their organelle populations varied at individual circadian rates.
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  • 94
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    Cell & tissue research 211 (1980), S. 251-268 
    ISSN: 1432-0878
    Keywords: Somatostatin ; Luliberin (LRF) ; Intercellular clefts (brain) ; Immunoreactive glia-like cells ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary With the aid of electron microscopic immunocytochemistry following the application of antisera against somatostatin and luliberin (LRF), a labeling of the intercellular clefts in different areas of the brain was observed. This labeling is especially conspicuous near the basal pole of the cuboidal ependymal cells, but is also generally present in all regions containing neurohormone-producing perikarya or their processes (for example, the preoptic area, the basal ganglia and the cortex). Furthermore, in all these regions displaying labeled intercellular clefts, glialike cells and sparsely ciliated ependymal cells are found, the secondary lysosomes of which exhibit an immunoreactivity resembling that observed in the intercellular clefts. As sources of the immunoreactive material the following possibilities are discussed: (i) perikarya producing somatostatin or LRF, situated in the wall of the third ventricle and sending fibers between the cuboidal ependymal cells, (ii) hypothalamic and extrahypothalamic projections of both peptidergic systems, and (iii) in the case of somatostatin, immunoreactive perikarya in the cortex.
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    Cell & tissue research 211 (1980), S. 493-501 
    ISSN: 1432-0878
    Keywords: Hypothalamo-hypophysial system ; Rat ; Tanycytes ; Transport ; Ontogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Transport of ferritin and horseradish peroxidase from the 3rd ventricle to the median eminence was examined in rats during the perinatal life, the time when functional interrelations between hypothalamus and hypophysis are established. Protein tracers injected into the lateral ventricle are adsorbed on the apical surface of the tanycyte, mainly on its protrusions or in indentations. On the 18th day of prenatal life a few small bleblike protrusions are observed. After birth microvilli appear. In time their concentration increases to result in an increase of adsorbed substances. They are taken up by smooth and coated pinocytotic vesicles and transported to the basal portion of the cell or to the intercellular space bypassing junctional complexes. In addition to pinocytotic vesicles protein tracers fill channels of smooth ER or Golgi complex and multivesicular bodies illustrating a process probably involved in metabolic or secretory processes.
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  • 96
    ISSN: 1432-0878
    Keywords: Motoneurones ; Triceps surae muscle ; Retrograde labelling (Evans blue) ; Excitability ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Evans blue was injected into either the medial and lateral gastrocnemius or the soleus muscle of adult albino rats to mark retrogradely the corresponding motoneurones in the spinal cord. The labelled motoneurones were identified by the red fluorescence of their perikarya in the ventral horn of segments L4–L6. In addition, a monosynaptic reflex action potential was recorded only in the ventral roots L4–L6 after stimulation of the nerves to the medial and lateral gastrocnemius and the soleus muscle. Excitability and reflex latencies of labelled and unlabelled motoneurones of segments L4–L6 as well as the conduction velocities of their axons were measured. Apart from a small but statistically nonsignificant increase in excitability, no functional differences were found between labelled and control neurones. Thus, retrograde labelling of motoneurones with Evans blue prior to performing electrophysiological experiments has the advantage that the marked motoneurones can be identified under the fluorescence microscope without the need of additional staining or fixation.
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  • 97
    ISSN: 1432-0878
    Keywords: CRF ; Vasopressin ; Adrenalectomy ; Rat ; Histology
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Summary In female Wistar rats the influence of adrenalectomy and NaCl administration on the amount of “classical” neurosecretory material (cNSM) in the supraoptico-hypophysial system and on vasopressin-like substance-containing granules (vlG) in the outer layer of the median eminence has been studied. In conjunction with appropriate sodium replacement, adrenalectomy induces an increase in the amount of vlG but does not alter the amount of cNSM. Administration of hypertonic saline diminishes cNSM but has no or only little influence on the amount of vlG. From the findings it is concluded that cNSM and vlG, in spite of their identical histochemical and immunohistochemical properties, have different functions. The functional significance of the vlG is discussed.
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    Cell & tissue research 212 (1980), S. 443-455 
    ISSN: 1432-0878
    Keywords: LRF-immunoreactive perikarya ; Preoptic area ; Light and electron microscopic immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary At the light microscopic level, following immunostaining with a single antiserum against luliberin (LRF), two types of hormone-producing perikarya in the preoptic area are demonstrated. The two cell types differ in their morphological features: a bipolar, smooth-contoured cell type can be differentiated from an irregularly contoured unipolar type. Intermediate forms between both cell types occurring in the same area are not observed. Electron microscopically, both cell types contain labeled granules of similar size and immunoreactivity. It is dicussed whether the uneven surface of the one cell type is due to areas of synaptic contacts, and whether both cell types are integrated in different neuronal and functional circuits. Moreover, at the ultrastructural level, from the irregularly contoured LRF-producing perikarya a further positively stained cell type, probably a glial cell, can be differentiated. The specific labeling of the latter is caused by its content of immunoreactive lysosomal bodies. Differentiation between the labeled glial cells and the irregularly contoured LRF-producing perikarya is not possible at the light microscopic level.
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  • 99
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 212 (1980), S. 457-464 
    ISSN: 1432-0878
    Keywords: Somatostatin immunoreactivity ; Cortex ; Hypothalamus ; Light and electron microscopic immunocytochemistry ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using an antibody against somatostatin (antiserum “F”), two somatostatin-immunoreactive systems, (i) a hypothalamic and (ii) an extrahypothalamic cortical system, are demonstrated in the rat. Another antiserum raised against somatostatin (antiserum “BS 102”) stains only the axons but not the perikarya of the hypothalamic system; the cortical somatostatin system does not react with this antiserum. The electron microscopic findings do not allow decision whether the above-mentioned hypothalamic and cortical neurons possess a common prohormonal form of somatostatin, immunoreactive only with antiserum “F”. They show, however, that the granules in both neuronal systems differ considerably; in the cortical neurons they measure approximately 65 nm in diameter, in the hypothalamic neurons 90–120 nm in diameter. Thus, both somatostatin systems are different and independent from one another.
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