Regression analysis of the spontaneous spike activity of neurons in snail ganglia

Regression analysis of the spontaneous spike activity of neurons in Helix pomatia was carried out with the aim to establish the statistical parameters of this activity under constant experimental conditions and during longer time intervals. The activity of 38 randomly chosen neurons in visceral and parietal ganglia, penetrated by microelectrodes and activated either endogenously by pacemaker potentials or by synaptic inputs, was recorded during time intervals lasting from 20 min to 3 h. The main results of the statistical analyses are presented in the table where the parameters of both cell types are listed. The validity of the regression analysis applied here is discussed from the point of the possibility it offers for carrying on the data processing quickly and without applying complex calculating means. The results are also considered regarding the current interest of our research group.     

Untersuchung der eiweißspindeln des kakteen-X-Virus mit fluoreszierenden Antikörpern

A?koliv na zá kladě mnoha pokus? se p? edpokládalo, ?e tzv. bÍlkovinná v?etena v buňkách tzn. buně?né inkluse X-viru kaktus? (Ca XV), jsou slo?ena z ?etních prodlou?ených ?ásti Ca XV, p?esto to dosud nebylo proká zá no. Proto jsme se pokusili pomocÍ fluoreskujÍcÍch protilátek doká ?at, ?e bilkovinná v?etena jsou skute?ně agregáty virových ?ástic. V těto práci jsme pouzili tzv. nep?Ímé metody. Nejprve jsme p? sobili na buňky obsahujÍci tato v?etena homologiokým antisé rem proti Ca XV, zÍskanym imunizacÍ králÍk? a teprve potom jsme buňky vlo?ili do roztoku fluoreskujicÍch protilátek proti králicimu γglobulinu. BÍlkovinná v?etena svitila potom ve fluorescen?nÍm mikroskopu silně ?lutozeleně (bylopou?ito fluoresceinisothiocyaná tu). Tato fluorescence ná m uká zala, ?e nastala pozitivnÍ reakce a ?e bÍlkovianá v?etena jsou slo?ena z virových ?ástic. ?etné kontrolnÍ pokusy potvrdily ná? základnÍ pokus.     

Importance de l'étude de la répartition écologique pour la taxonomie des éponges calcaires

Résumé 1. Les travaux deSarà (1953) et deBurton (1963) ont remis en question la valeur systématique des caractères morphologiques dans la classification des Eponges Calcaires, et ont proposé de considérer de nombreuses formes connues comme des variétés individuelles et régionales d'espèces très plastiques et variables. Nous avons essayé de préciser, par l'observation directe en plongée libre, la distribution et les préférences écologiques des Calcaires, de définir ainsi les limites naturelles de leurs populations, et d'étudier ensuite la variabilité des caractères morphologiques à l'intérieur de ces populations.2. Nous exposons ici l'exemple des espèces des genresClathrina etAscandra, étudiées en Adriatique, dans les régions de Marseille et de Roscoff. Leur distribution est en rapport direct et très précis avec l'exposition aux vagues et à la lumière, à tel point que sur une surface réduite plusieurs espèces se succèdent et se remplacent en fonction de l'exposition de l'endroit. Dans la règion de Roscoff cette distribution est plus large ce qui est dû aux effets des marées, mais les zones écologique préférentielles pour les espèces deClathrina ont pu être établies en fonction de l'importance de l'apport des sédiments par les eaux côtières.3. La possibilité de définir des populations dont la distribution est très précisemment délimitée malgré une coexistence dans un espace réduit, et qui ne sont pas réliées par les formes transitoires, permet d'éliminer l'hypothèse de la cospécificité de ces populations. Elle permet également d'établir les variations morphologiques possibles au sein d'une espèce, de retenir les caractères significatifs pour la classification, et finalement de distinguer les espèces qui se ressemblent morphologiquement. Dans le cas d'animaux qui, commeClathrina, possèdent très peu de caractères utilisables en systématique, c'est la seule façon de résoudre les problèmes de leur taxonomie.

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The importance of research on the ecological distribution for the taxonomy of calcareous sponges

The particular difficulties of the taxonomy of calcareous sponges are due to their great plasticity and their capacity for adaptation which obscure the natural limits of species. An attempt was made to define the natural populations of the Mediterranean species of the generaClathrina andAscandra through a study of their ecological distributions. The populations not connected by the transitory forms were defined by their ecological preferences, and, as they are found in a close cohabitation, were treated as having the specific values. The variability of different morphological features is discussed, the features significant for taxonomy are pointed out and the morphologically close species are defined.

     

Plastid transformation in greening scales of the onion bulb (Allium cepa,Alliaceae)

The greening of the upper part of the outerAllium cepa L. bulb scales, in particular along the vascular regions, is limited to the hypodermal cells in which typical leucoplasts are transformed to normal and functional chloroplasts. This process is light dependent and cannot afterwards be reversed or modified by darkness. The changes in fine structure are described and briefly discussed.Dedicated to Prof. DrLothar Geitler on the occasion of his 90th birthday and 55 years after the publication of his Grundriß der Cytologie.     

Salt-soluble lectins of corn grain

Lectins extracted from corn (Zea mays L.) kernel with Tris-HCl buffer pH 7.5 were isolated from the crude extract by affinity chromatography on Sepharose 6B-N-acetyl-d-galactosamine and Sepharose 6B-methylα-d-mannoside, and also by lectin affinity chromatography using concanavalin A and Lens culinaris lectin as ligands. According to preferential monosaccharide specificity, salt-soluble lectins of corn seed comprise at least two distinct types: N-acetyl-d-galactosamine-interactive and mannose-interactive lectins. The extracted lectins are unstable, with a tendency to form aggregates during storage.     

Hypervariability of intronic simple (gt)n(ga)m repeats in HLA-DRB genes

We have investigated the extent of DNA variability in intronic simple (gt)_n(ga)_m repeat sequences and correlated this to sequence polymorphisms in the flanking exon 2 of HLA-DRB genes. The polymerase chain reaction (PCR) was used to amplify a DNA fragment containing exon 2 and the repeat region of intron 2. The PCR products were separated on sequencing gels in order to demonstrate length hypervariability of the (gt)_n(ga)_m repeats. In a parallel experiment, the PCR products were cloned and sequenced (each exon 2 plus adjacent simple repeats) to characterize the simple repeats in relation to the HLA-DRB sequences. In a panel of 25 DRB1, DRB4, and DRB5 alleles new sequences were not detected. Restriction fragment length polymorphism (RFLP) subtyping of serologically defined haplotypes corresponds to translated DNA sequences in 85% of the cases, the exceptions involving unusual DR/DQ combinations. Many identical DRB1 alleles can be distinguished on the basis of their adjacent simple repeats. We found group-specific organization of the repeats: the DRw52 supergroup repeats differ from those of DRB1*0101, DRB4*0101, and DRB5*0101 alleles and from those of pseudogenes. Finally, we amplified baboon DNA and found a DRB allele with extensive similarity to DRB1 sequences of the DRw52 supergroup. The simple repeat of the baboon gene, however, resembles that of human pseudogenes. In addition to further subtyping, the parallel study of polymorphic protein and hypervariable DNA alleles may allow conclusions to be drawn on the relationships between the DRB genes and perhaps also on the theory of trans-species evolution.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession number M 34258.     

Determination of trace elements in standard reference materials by the ko-standardization method

Biological Trace Element Research - The ko-standardization method is suitable for routine multielement determinations by reactor neutron activation analysis (NAA). Investigation of NIST standard...     

Structural and functional homology between the 29 kD rat liver nucleoprotein and the high mobility group 1 protein

A 29 kD soluble rat liver nucleoprotein (p29) has increased binding affinity for the hormone responsive element (RE) of the rat haptoglobin (Hp) gene during the acute-phase reaction. In this work the possibility of its structural and functional homology to the high mobility group 1 (HMG1) nonhistone protein constituent of chromatin was examined. The results of two-dimensional gel electrophoresis, Southwestern and Western immunoblot analyses, showed that p29 and HMG1 are homologous protein species. On the basis of in vitro and in vivo phosphorylation/dephosphorylation experiments, we discuss the modulatory role of phosphate groups in view of the structure and function of p29.