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Showing papers by "University of Vienna published in 1977"


Journal ArticleDOI
TL;DR: In this article, a detailed study of a special type of functional organization and demonstrates its relevance with respect to the origin and evolution of life is presented, which can be formally represented by the concept of the quasi-species.
Abstract: This paper is the first part of a trilogy, which comprises a detailed study of a special type of functional organization and demonstrates its relevance with respect to the origin and evolution of life. Self-replicative macromolecules, such as RNA or DNA in a suitable environment exhibit a behavior, which we may call Darwinian and which can be formally represented by the concept of the quasi-species. A quasi-species is defined as a given distribution of macromolecular species with closely interrelated sequences, dominated by one or several (degenerate) master copies. External constraints enforce the selection of the best adapted distribution, commonly referred to as the wild-type. Most important for Darwinian behavior are the criteria for internal stability of the quasi-species. If these criteria are violated, the information stored in the nucleotide sequence of the master copy will disintegrate irreversibly leading to an error catastrophy. As a consequence, selection and evolution of RNA or DNA molecules is limited with respect to the amount of information that can be stored in a single replicative unit. An analysis of experimental data regarding RNA and DNA replication at various levels of organization reveals, that a sufficient amount of information for the build up of a translation machinery can be gained only via integration of several different replicative units (or reproductive cycles) through functional linkages. A stable functional integration then will raise the system to a new level of organization and thereby enlarge its information capacity considerably. The hypercycle appears to be such a form of organization.

1,364 citations


Journal ArticleDOI
21 Jul 1977-Nature
TL;DR: If Langerhans cells are indeed involved in immunological reactions, they should bear some of the surface markers characteristics of cells with known immunological functions, and it is shown that they carry receptors for Fc and C3.
Abstract: THE mammalian epidermis contains a system of dendritic cells, eponymously referred to as Langerhans cells, whose functions are obscure. It is, however, accepted that Langerhans cells are of mesenchymal origin and since they are known also to occur in the dermis, lymph nodes, thymus, and other organs, the concept of Langerhans cells has widened to encompass a cellular system populating the connective tissues and certain stratified squamous epithelia of mammals1. Among the many hypotheses about their biological significance they have been considered to represent immunocompetent cells or cells which might capture antigenic materials2, but there is insufficient evidence for this. Lymphocytes have been observed to be closely associated with Langerhans cells in delayed type hypersensitivity reactions to dinitrochloro-benzene in guinea pigs3; and when guinea pigs passively sensitised with lymphocytes from ferritin-hypersensitive donors, were challenged with ferritin, ferritin-containing Langerhans cells were observed in the draining lymph nodes of the challenged animals4. Metals and certain amines have an affinity for Langerhans cells in vitro5, but since they can phagocytose ferritin and other substances without previous sensitisation1, doubt remains whether they are immunologically engaged in the uptake and transport of potentially antigenic material. If Langerhans cells are indeed involved in immunological reactions, they should bear some of the surface markers characteristics of cells with known immunological functions, and we have now shown that they carry receptors for Fc and C3.

516 citations


Journal ArticleDOI
TL;DR: In this article, the role of convention in various definitions of clock synchronization and simultaneity is investigated, and two principal methods of synchronization can be considered: system internal and system external synchronization.
Abstract: The role of convention in various definitions of clock synchronization and simultaneity is investigated. We show that two principal methods of synchronization can be considered: system internal and system external synchronization. Synchronization by the Einstein procedure and by slow clock transport turn out to be equivalent if and only if the time dilatation factor is given by the Einstein result (1−v 2)1/2. An ether theory is constructed that maintains absolute simultaneity and is kinematically equivalent to special relativity.

404 citations


Journal ArticleDOI
TL;DR: Two groups of lithotrophic bacteria, the existence of which may be expected on evolutionary and thermodynamical grounds, have not yet been detected: photosynthetic, anaerobic, ammonia bacteria, analogous to coloured sulphur bacteria, and chemosynthetic bacteria that oxidize ammonia to nitrogen with O2 or nitrate as oxidant.
Abstract: Two groups of lithotrophic bacteria, the existence of which may be expected on evolutionary and thermodynamical grounds, have not yet been detected: (A) photosynthetic, anaerobic, ammonia bacteria, analogous to coloured sulphur bacteria, and (B) chemosynthetic bacteria that oxidize ammonia to nitrogen with O2 or nitrate as oxidant.

375 citations



Journal ArticleDOI
TL;DR: The acoustic behaviour of 15 sympatric and synchronically breeding species of frogs in an area of floating meadows near Manaus (Brazil) was studied for a period of 8 months to study the mating calls of these species.
Abstract: The acoustic behaviour of 15 sympatric and synchronically breeding species of frogs in an area of floating meadows near Manaus (Brazil) was studied for a period of 8 months. The calling positions of each species can be identified with certain physiognomic types of vegetation.Sound analyses were used to compare the mating calls. The main variables are dominant frequency, call duration and pulse repetition rate. Each of the 15 species has a distinct mating call and differs from the acoustic behaviour of each other one. Eleven species are separated in their dominant frequency ranges within their specific calling sites. Species sharing emphasised frequency ranges within identical calling sites differ greatly in at least two temporal variables.The roles of calling position, spectral, and temporal features of mating calls in species recognition and premating reproductive isolation are discussed.

192 citations


Journal ArticleDOI
TL;DR: In this article, the potential energy, the forces and the virial in a computer ensemble of N polarizable point dipoles were analyzed using an iterative scheme for use in molecular dynamics calculations.

187 citations


Journal ArticleDOI
TL;DR: In this paper, first-order tests of special relativity are based on a comparison of clocks synchronized with the help of slow clock transport with those synchronized by the Einstein procedure, which enables the measurement of the one-way velocity of light and is equivalent to a measurement of time dilatation factor.
Abstract: First-order tests of special relativity are based on a comparison of clocks synchronized with the help of slow clock transport with those synchronized by the Einstein procedure. This comparison enables the measurement of the one-way velocity of light and is equivalent to a measurement of the time dilatation factor. The accuracy of present measurements is of the order 10−7, yielding an upper limit of 3 cm/sec for the ether drift.

176 citations


Journal ArticleDOI
TL;DR: Fluvoxamine has been characterized as a potential anti‐depressant drug with almost exclusively 5‐hydroxytryptamine (5‐HT) uptake inhibiting properties.
Abstract: 1. On the basis of both in vitro and in vivo experiments fluvoxamine has been characterized as a potential anti-depressant drug with almost exclusively 5-hydroxytryptamine (5-HT) uptake inhibiting properties. 2. Fluvoxamine is effective in inhibiting 5-ht uptake by blood platelets and brain synaptosomes. Due to inhibition of the membrane pump the compound prevents 5-HT depletion by the tyramine-derivatives H 75/12 and H 77/77. As a result of the interference with the neuronal re-uptake mechanism for 5-HT, fluvoxamine produces a decreased 5-HT turnover in the brain. Effects of 5-hydroxytryptophan (5-HTP) are potentiated in mice and in combination with pargyline, fluvoxamine induces 5-HT-like behavioural effects. 3. In contrast to tricyclic antidepressants, noradrenaline uptake processes are either unaffected or only slightly inhibited by fluvoxamine. The noradrenaline depleting effects of tyramine derivates are not influenced by fluvoxamine. Reserpine effects, such as ptosis are affected only at very high doses of the test compound. The antagonism by fluvoxamine of the reserpine-induced lowering of the pentamethylenetetrazole convulsive threshold can be regarded as due to an effect upon 5-HT uptake. In contrast to the effects of desmethylimipramine and imipramine, no stimulatory effects are found in rats when rapidly acting reserpine-like compounds are given following a dose of fluvoxamine.

168 citations


Journal ArticleDOI
TL;DR: Cerebral amyloid angiopathy may be considered a rare but important cause of cerebral hemorrhage in the aged, and the “vascular” type of presenile dementia, occasionally complicated by focal cerebrovascular lesions or bleeds, is considered a variant of Alzheimer's disease.
Abstract: More than 1400 necropsies performed on patients with either a non-traumatic cerebral hemorrhage (400 cases) or with dementia over the age of 55 (1010 cases), or both, have been reviewed. There were 15 cases in which a cerebral hemorrhage had occurred together with cerebral amyloid angiopathy all of whom had been demented. Eight of the 15 patients were hypertensive. The 7 non-hypertensives showing only the amyloid change included two cases of “atypical” Alzheimer's disease with acute neurological features, and 5 cases of senile dementia (aged 72 to 78 years) coupled with focal neurological disorders. In the hypertensive patients, aged 67 to 86 years, with a progressive dementing syndrome and acute neurological signs, multiple ball-like hemorrhages (7 cases) and/or cerebral hematomas (3 cases) were associated with a combination of amyloid and hyalinar (hypertensive) angiopathy, often affecting segments of the same pial and cortical vessels. From these data and recent reports on lethal cerebral hemorrhage occurring spontaneously or after neurosurgical procedures in demented old people, cerebral amyloid angiopathy, which is not necessarily associated with systemic amyloidosis or severe (pre)senile cerebral degeneration, may be considered a rare but important cause of cerebral hemorrhage in the aged. The “vascular” type of presenile dementia, occasionally complicated by focal cerebrovascular lesions or bleeds, is considered a variant of Alzheimer's disease. The mechanism leading to formation of cerebral amyloid is unknown.

129 citations


Journal ArticleDOI
TL;DR: The ionic relations in halophytes from the region east of Neusiedler Lake in Austria have been investigated and the general problems of salt tolerance, on the other hand, the taxonomical and ecological aspects are discussed.
Abstract: The ionic relations in halophytes from the region east of Neusiedler Lake in Austria have been investigated. The study encompasses the following compounds: Na, K, Mg, Ca; Cl, SO4, phosphate, nitrate, and organic acids.

Journal ArticleDOI
TL;DR: The Arabian Shield is divided into several segments by ophiolite zones and the segments display features of island arcs with respect to their magmatic evolution as well as their mineralization as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this paper, the second-order optical tests of special relativity are discussed within the framework of the test theory developed previously, and several experiments are suggested to improve this-accuracy.
Abstract: Various second-order optical tests of special relativity are discussed within the framework of the test theory developed previously. Owing to the low accuracy of the Kennedy-Thorndike experiment, the Lorentz contraction is known by direct experiments only to an accuracy of a few percent. To improve this-accuracy several experiments are suggested.

Journal ArticleDOI
TL;DR: Treatment of dewaxed sections of formalin-fixed paraffin embedded material with 0.1% pronase for 15 min at 37 degrees C prior to the performance of the unlabelled antibody-enzyme (PAP) procedure greatly enhanced its sensitivity.

Journal ArticleDOI
TL;DR: The best known value of the fifth virial coefficient for a hard-sphere fluid was until now: B5/tB42 = 0.110277 ± 0.000014 as mentioned in this paper.
Abstract: The best known value of the fifth virial coefficient for a hard-sphere fluid was until now: B5/tB42 = 0.110277 ± 0.000014, B2 being the second virial coefficient. In the present work, B5 is determined more accurately, the result being B5/tB42 = 0.110252±0.000001. Moreover, the values of B6 and B7 given in the literature are re-examined and slightly modified. Then, estimates of B8, B9 and B10 are given using several approximations.

Journal ArticleDOI
TL;DR: Giemsa techniques have refused to reveal G-banding patterns in plant chromosomes, but the striking correspondence of pachytene chromomeres and mitotic G-bands in higher vertebrates suggests that pachyTene chromomes are G- band equivalents, and that this may also be the case in plants.
Abstract: Giemsa techniques have refused to reveal G-banding patterns in plant chromosomes. Whatever has been differentially stained so far in plant chromosomes by various techniques represents constitutive heterochromatin (redefined in this paper). Patterns of this type must not be confused with the G-banding patterns of higher vertebrates which reveal an additional chromosome segmentation beyond that due to constitutive heterochromatin. The absence of G-bands in plants is explained as follows: 1) Plant chromosomes in metaphase contain much more DNA than G-banding vertebrate chromosomes of comparable length. At such a high degree of contraction vertebrate chromosomes too would not show G-bands, simply for optical reasons. 2) The striking correspondence of pachytene chromomeres and mitotic G-bands in higher vertebrates suggests that pachytene chromomeres are G-band equivalents, and that this may also be the case in plants. G-banded vertebrate chromosomes are on the average only 2.3 times shorter in mitosis than in pachytene; the chromomeric pattern therefore still can be shown. In contrast, plant chromosomes are approximately 10 times shorter at mitotic metaphase; their pachytene-like arrangement of chromomeres is therefore no longer demonstrable.

Journal ArticleDOI
TL;DR: Light may unspecifically increase the permeability of the plasma-lemma probably via the ATP level, and 3×10-3 M N-ethylmaleimide induces Na uptake, and DCCD induced Na influx is about 5 times faster in light than in darkness, and the steady state is reached much earlier in light.
Abstract: The Na level inside cells of Anacystis nidulans is lower than in the external medium reflecting an effective Na extrusion. Na efflux is an active process and is driven by a Na+/H+-antiport system. The necessary H+-gradient is generated by a proton translocating ATPase in the plasmalemma. This ATPase (electrogenic proton pump) also produces the membrane potential (about -110 mV) responsible for K accumulation. N,N′-dicyclohexylcarbodiimide (DCCD) inhibits the ATPase and the H+-gradient completely, but the membrane potential is only reduced (<-70 mV), since K efflux initiated by DCCD maintains the potential partly by diffusion potential.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the ag-stainability of the nucleolus organizer region (NOR) in the acrocentric chromosomes identified by Q-banding of cultured lymphocytes in 51 karyotypically normal persons.
Abstract: The Ag-stainability of the nucleolus organizer region (NOR) was studied in the acrocentric chromosomes identified by Q-banding of cultured lymphocytes in 51 karyotypically normal persons (31 males and 20 females). A consistent pattern of Ag-positive NORs was found in each individual. Ninety percent of the individuals have a modal number of 8–10 Ag-positive NORs per cell. The frequency of Ag-positive NORs is similar in all five acrocentrics. A statistically nonsignificant lower frequency is found in chromosome 22. Ag-negative NORs on both homologues were found in four cases. The observed frequency distribution of individuals with homozygous NOR-positive, heterozygous, and homozygous negative acrocentric chromosomes was in accordance with the Hardy-Weinberg law in all five pairs of the acrocentric chromosomes as well as in total. No sex difference was observed in our material.

Journal ArticleDOI
TL;DR: The AT specificity of the fluorochromes DIPI and DAPI and the GC specificity of mithramycin are evidenced by observations in human, mouse, and bovine chromosomes.
Abstract: The AT specificity of the fluorochromes DIPI and DAPI and the GC specificity of mithramycin are evidenced by observations in human, mouse, and bovine chromosomes. DIPI and DAPI produce a pattern similar to Hoechst 33258 in all three species, whereas mithramycin results in a reverse pattern. The AT-rich centromeric heterochromatin in mouse is brilliantly stained by DIPI or DAPI and remains nearly invisible after mithramycin staining. In the GC-rich centromeric heterochromatin of cattle the opposite behavior is observed.

Journal ArticleDOI
D. Kraft1, A. Roth, P. Mischer1, H. Pichler1, H. Ebner1 
TL;DR: Sera from 204 patients with acute or former reactions following penicillin treatment were investigated by RAST with specificity for benzylpenicilloyl and phenoxymethyl‐penicillsoyl, and total serum IgE measured by RIST and the RAST results showed similar patterns.
Abstract: Sera from 204 patients with acute or former reactions following penicillin treatment were investigated by RAST with specificity for benzylpenicilloyl and phenoxymethyl-penicilloyl. The IgE antibody levels were followed up for of more than 2 years. Positive results could be observed at the time of the acute reactions and the weeks following; later months or years in many cases. Occasionally negative RAST results occurred within 30 days; on the other hand high levels of specific IgE persisted for years in some patients. Total serum IgE measured by RIST and the RAST results showed similar patterns, with mean levels of 568 u/ml between 0 and 30 days after the penicillin allergic reaction, 286 u/ml between 30 days and 1 year, and 195 u/ml in cases after 1 year corresponded well with the observed decline in specific IgE. Skin tests performed with penicilloyl-polylysine in 118 patients showed an overall correlation of 91-5% with the RAST results. Differences between the two test systems were observed in patients with a long interval between the test and the last allergic attack. None of the patients with proved penicillin allergy had atopic diseases or a history of atopy. On the basis of these findings it is suggested that the determination of both circulating specific IgE and total IgE should be of great value for diagnostic purposes during acute drug reactions and in the months immediately afterwards.

Book ChapterDOI
01 Jan 1977
TL;DR: The hypothesis is presented that there is a strategy to limit direct herbivory on marine macrophytes, which constitutes an energy drain on the primary producer compartment without a feedback reward loop through the products of remineralization as in similar terrestrial ecosystems.
Abstract: A stand of Posidonia oceanica DELILE at the island of Ischia (Gulf of Naples) was investigated as to its production and the fate of the organic matter produced A site in 4 m depth with a mean leaf biomass of 115 kg dry weight had a net production of 152 gC per square meter and day during the period of May to July 1976 About 50% of this production is consumed in the system, approximately 30% exported continuously The only potential herbivore, the sea urchin Paracentrotus lividus LAM consumes about 9-10% of the net production, but does not attack living Posidonia tissue The hypothesis is presented that there is a strategy to limit direct herbivory on marine macrophytes, which constitutes an energy drain on the primary producer compartment without a feedback reward loop through the products of remineralization as in similar terrestrial ecosystems

Journal ArticleDOI
TL;DR: DIPI and DAPI seem to be strictly AT specific fluorochromes like Hoechst 33258, which are highly resistant to UV-irradiation and fluorescence intensity is stronger than in quinacrines.
Abstract: DIPI and DAPI produce distinct fluorescent bands in human chromosomes similar to quinacrine banding patterns. Additionally, the AT rich secondary constrictions in the chromosomes Nos. 1, 9 and 16 are brightly fluorescent. On the other hand the brilliantly fluorescent regions after staining with quinacrine mustard in the chromosomes Nos. 3 and 4, satellites and some other regions in the acrocentric chromosomes are less striking. The distal part of the Y, however, is clearly discernible. Thus DIPI and DAPI seem to be strictly AT specific fluorochromes like Hoechst 33258.

Journal ArticleDOI
TL;DR: Theoretical and experimental evidence is presented for the possibility of three pathways for electron ejection: (1) a monophotonic pathway via the fluorescent state, which most probably does not involve the lowest triplet state; (2) a multiphotonic pathway requiring higher excitation energies, which takes place in competition with internal conversion to the fluorescent states; and (3) a consecutive biphotonic pathway in which the lowest triplet state absorbs the second photon, and which can become predominant at high intensities, e.g. under flash conditions as discussed by the authors.
Abstract: Abstract. The dependence of primary photophysical and photochemical processes, especially of electron photoejection, in phenol and related compounds in aqueous solution on excitation intensity and excitation energy is examined. Theoretical and experimental evidence is presented for the possibility of three pathways for electron ejection: (1) A monophotonic pathway via the fluorescent state, which most probably does not involve the lowest triplet state; (2) a monophotonic pathway requiring higher excitation energies, which takes place in competition with internal conversion to the fluorescent state; and (3) a consecutive biphotonic pathway in which the lowest triplet state absorbs the second photon, and which can become predominant at high intensities, e.g. under flash conditions. It is shown that this model reconciles apparently conflicting results published in the literature.

Journal ArticleDOI
TL;DR: In this paper, a monomer-dimer equilibrium for pyrromethenones was deduced by means of absorption and fluorescence spectroscopy and measurement of a colligative property.
Abstract: Depending on solvent polarity and concentration a monomer—dimer equilibrium for pyrromethenones was deduced by means of absorption and fluorescence spectroscopy and measurement of a colligative property. The monomer could be characterized as asyn-(Z) form with a dihedral angle at the methine single bond of about fourty degrees using the lanthanide shift technique and nuclearOverhauser effect studies. Two types of dimer geometry with differing bond strengths were found by comparingPPP calculation results with the measured absorption spectra and the liquid crystal induced circular dichroism. The (Z) isomers can be transformed to the corresponding (E) isomers by means of a photoreaction. The latter is thermally stable but rather sensitive against oxygen, light and protons, an effect which varies strongly with the substitution pattern of the pyrrole fragment thus enabling isolation in certain cases only.

Journal ArticleDOI
TL;DR: The ultrastructural localization of in vivo-bound IgA and circulating IgA antibasement membrane zone antibodies fixed to substrate tissue in vitro was found to be in the uppermost strata of the dermis below the basal lamina.

Journal ArticleDOI
TL;DR: Nucleophilic substitution reactions of Hydroxysteroids using Triphenylphosphane/diethylazodicarboxylate in benzene was described in this article, where it was not possible to run this substitution process in the hitherto used solvent THF.
Abstract: Nucleophilic Substitution Reactions of Hydroxysteroids using Triphenylphosphane/diethylazodicarboxylate Nucleophilic substitution reactions by means of the title reagent on various more or less hindered steroid alcohols with suitable nucleophils in benzene is described. It was not possible to run this substitution process in the hitherto used solvent THF. Cholestan-3α-ol (1) was transformed to the 3β-substituted products 3β-benzoyloxy-cholestane (1a) and 3β-azido-cholestane (1b). Testosterone (2) affords with the corresponding nucleophils after short heating in benzene the inverted 17α-substituted products 3a, 3b and 3c. Analogously the 17α-azido-derivative 5a arises from 17β-hydroxy-androst-3-on (4). In the presence of a ketogroup in the substrate a competitive reaction can occur as it is shown in the case of cholestan-3-on (6): the products are the en-hydrazo-dicarboxylate-steroids 7a and 7b. The sterically very hindered 11α-position in 11α-hydroxy-4-pregnen-3,20-dion (8) can be transformed also to the 11β-azide 9a. The substitution of a 6β-hydroxy group in androstane-3β, 6β, 17β-triol-3,17-diacetate (10) to the 6α-azide 11a affords the elimination product 12 as main component. Trans-diaxial vicinal diols such as cholestane-2β,3α-diol (13) give a mixture of the α- and β-oxiranes 14a and 14b.

Journal ArticleDOI
TL;DR: In this article, a subdivision of the four crystallographically non-equivalent lattice sites into seven (eight) groups for the Th2Zn17 (Th2Ni17) compounds is concluded, by neglecting all contributions of the asymmetry parameter.
Abstract: Mossbauer measurements are performed on rhombohedral Y2F17 in the temperature range 5 to 300 K and in fields up to 20 kOe. The dipole fields and the crystalline electric field gradients are calculated for both structure types. From this a subdivision of the four crystallographically non-equivalent lattice sites into seven (eight) groups for the Th2Zn17 (Th2Ni17) compounds is concluded, by neglecting all contributions of the asymmetry parameter. An exact allocation of the resulting subspectra to these different Fe sites is only possible for the c (f)- and a fraction of the d (g)-sites. The field and the temperature dependence of the hyperfine interactions of the distinguishable Fe sites are discussed. Im Temperaturbereich 5 bis 300 K und in Feldern bis 20 kOe werden Mosbauermessungen am rhomboedrischen Y2Fe17 durchgefuhrt. Die Dipolfelder und die kristallelektrischen Feldgradienten werden fur die beiden auftretenden Strukturtypen berechnet, wobei eine Unterteilung der vier kristallographisch nichtaquivalenten Gitterplatze in sieben (acht) Untergruppen fur die Th2Zn17 (Th2Ni17)-Verbindungen bei Vernachlassigung aller Beitrage des Asymmetrieparameters erhalten wird. Eine genaue Zuordnung dieser Subspektren zu den verschiedenen Fe-Platzen ist jedoch nur fur die c (f)- und fur einen Teil der d (g)-Platze moglich. Die Feld- und Temperaturabhangigkeit der Hyperfeinwechselwirkung fur die unterschiedlichen Fe-Platze wird diskutiert.

Journal ArticleDOI
TL;DR: The in vitro effect of human placental lactogen and the gravidity-specific beta1-Glycoprotein (SP-1) on the lymphocyte transformation was investigated and it was shown that simultaneous incubation of the lymphocytes with HPL or SP-1 together with PHA has no influence on the incorporation rate of H3-Thymidine.
Abstract: The in vitro effect of human placenta lactogen (HPL) and the gravidity-specificβ1-Glycoprotein (SP-1) on the lymphocyte transformation was investigated in 20 healthy women. It was shown that simultaneous incubation of the lymphocytes with HPL or SP-1 together with PHA has no influence on the incorporation rate of H3-Thymidine.

Journal ArticleDOI
TL;DR: In this paper, the authors studied the Ag-stainability of the nucleolus organizer region (NOR) in the acrocentric chromosomes identified by Q-banding in cultured lymphocytes from seven children with trisomy 21 and their parents.
Abstract: The Ag-stainability of the nucleolus organizer region (NOR) was studied in the acrocentric chromosomes identified by Q-banding in cultured lymphocytes from seven children with trisomy 21 and their parents. The observed Ag-NOR patterns were in accordance with chromosomal inheritance except for a slight intraindividual variation which might be explained mainly by technical causes. In two cases the meiotic nondisjunction could be attributed to one of the parents, once to the father, and once to the mother. It is concluded that the Ag-stainability of the NORs is in general a heritable characteristic of the acrocentric chromosomes in maximally activated cells as, e.g., cultured lymphocytes. It may reflect individual differences in the amount of rDNA as well as differences in the capacity for NOR activation.

Book ChapterDOI
01 Jan 1977
TL;DR: The distribution of Mysidacea has been studied in Strunjan Bay and islands off Rovinj (Istria, Yugoslavia) and underwater observations were made by diving, TV, and time-lapse-camera.
Abstract: The distribution of Mysidacea has been studied in Strunjan Bay and islands off Rovinj (Istria, Yugoslavia) Underwater observations were made by diving, TV, and time-lapse-camera Different species show a preference for certain bathymetric zones and, within a zone, occupy different substrates and distinct microhabitats or differ in period of activity, so that they are usually aggregated in monospecific swarms Occurrence of polyspecific swarms is referable to overlapping requirements and to interaction of species Swarm formation is controlled by two patterns: habitational and inter-individual responses The relative influence of both patterns differs in species - this is referable to different substrate-relations