Histones from the red alga,Rhodymenia palmata?

Résumé Protéines ont été extraites de l'algue rougeRhodymenia palmata, par les méthodes normalement utilisées pour les histones. Ces protéines diffèrent des histones du thymus de veau d'une façon marquée, mais elles ont des similarités fonctionelles.     

Die anorganischen Bestandteile des Honigtaues vonMegoura viciae Buckt

Summary In the honeydew ofMegoura viciae Buckt., sucking on the sieve tube sap ofVicia faba, the following cations are present in measurable quantities: potassium (13.0–14.1 mg/ml), sodium (0.04–0.051 mg/ml), magnesium (1.8–2.3 mg/ml) and calcium (0.07–0.09 mg/ml). There are only traces of copper, iron, manganese, zinc, cobalt and molybdenum. Amongst the anions, phosphate was found at 1.9–2.5 and chloride at 0.02–0.05 mg/ml, whereas nitrate and sulphate could not be detected.     

The histones ofDictyostelium discoideum

Summary The histones of the cellular slime mouldDictyostelium discoideum have been separated by electrophoresis using both acid urea and sodium dodecyl sulphate systems, and the gel pattern compared with that of histones fromPhysarum polycephalum and calf thymus.Dictyostelium is found to possess a full complement of H1, H2A, H2B, H3 and H4.     

A newTrichoplusia ni antennal receptor neuron that responds to attomolar concentrations of a minor pheromone component

Summary A newly discovered third class of sensillum trichodea on the antenna ofTrichoplusia ni contains an olfactory receptor neuron that responds to (Z)-9-tetradecen-1-ol acetate at 1×10^–18 M. The threshold of this neuron is 100–1000 times lower than the thresholds of two previously described pheromone-sensitive neurons that detect (Z)-7-dodecen-1-ol acetate and (Z)-7-tetradecen-1-ol acetate. The sensitivity and selectivity of this receptor neuron is evidence that (Z)-9-tetradecen-1-ol acetate may be important for sexual behavior.     

The histone deacetylase inhibitor trichostatin A influences the development of Drosophila melanogaster

We examined the consequences of the deacetylase inhibitor trichostatin A (TSA) on the development of Drosophila melanogaster. When fed to flies, TSA caused lethality and delayed development at concentrations as low as 5 μM, had stronger effects on males than females, and acted synergistically with mutations in the gene encoding the RPD3 deacetylase to cause notched wings, but did not appear to affect a SINA signaling pathway that is normally repressed by the SIN3 corepressor. These findings suggest that deacetylated histones play an important role in normal developmental progression and establish parameters for genetic screens to dissect the role of deacetylases in this process. Received 14 June 2001; received after revision 31 July 2001; accepted 21 August 2001     

Extraction and analysis of histone protein from the roots of three plant species

Résumé Des essais réitérés ont montré aux auteurs que la protéine extraite des racines d'Allium cepa, deVicia faba et dePisum sativum est identifiable à l'histone. L'analyse de l'amine acide des hydrolysates des histones ne révèle pas de différences entre les trois espèces végétales citées et le thymus de veau. Dans les végétaux, cependant, le rapport lysine-arginine est plus élevé.

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The research was partially supported by the US Atomic Energy Commission under Contract AT(11-1)826.     

Isolation of the two paragonial substances deposited into the spermatophores ofAcanthoscelides obtectus (Coleoptera,Bruchidae)

Summary Aqueous extracts from spermatophores ofAcanthoscelides obtectus (Coleoptera, Bruchidae) have been chromatographed on Sephadex G 25 and G 15 columns, the active fractions being further purified by preparative SiO₂ TLC. The isolation and properties of 2 biologically active compounds are reported. The paragonial substance A has a favourable action upon oogenesis, is a low molecular weight molecule (500–1000) and gives 1 single amino acid on hydrolysis, corresponding to glycin on TLC. The paragonial substance B is toxic, or an inhibitor of oogenesis at lower concentration, thus showing an antagonistic effect.     

High K+-induced release of somatostatin from the cortical preparation of rat brain

Summary Release of endogenous somatostatin (SRIF) from the rat cerebral cortical slices incubated in Krebs-bicarbonate buffer was increased from the basal rate of 3.4±0.6% of the total SRIF content in 15 min at [K⁺]_o=5.6 mM, to 13.1±1.6% upon raising the [K⁺]_o to 56.6 mM. The high-K⁺ evoked SRIF release was absent when Ca⁺⁺ in the medium was replaced by Mn⁺⁺. The isolated synaptosomes from rat cerebral cortex contain 13.2±3.1 ng SRIF/mg protein compared to 0.33±0.01 ng/mg protein in the cortical tissue as a whole, suggesting that nerve terminals are the main source of the peptide released upon membrane depolarization.The study was supported by a grant from the Medical Research Council of Canada. Results of this work have been published in part as abstracts: Can. Physiol.9, 45 (1978), and Fedn Proc.37, 665 (1978).The authors are greatly indebted to Dr M. Gotz and the Ayerst Research Laboratories for the most generous supply of the synthetic somatostatin.     

The influence of histone fraction F1 and ATP on the amplitude of contractions of the isolated right ventricle of rats

Résumé L'action de la fraction F₁ des histones et de l'ATP sur l'amplitude des contractions a été examinée sur le ventricule droit des rats blancs. On a constaté que l'ATP appliqué après l'arrêt des contractions dû à l'histone F₁ provoquait la reprise de celles-ci. La présence de l'ATP avant l'application des histones F₁ abaisse seulement l'amplitude, mais les contractions persistent jusqu'à la fin de l'expérience. L'application simultanée de l'ATP et des histones F₁ provoque une inhibition irréversible des contractions ventriculaires.     

Lokalisation zusätzlicher RNS-Synthese in Trypsin-behandelten Riesenchromosomen vonChironomus thummi

Summary After injection of buffered trypsin into nuclei of salivary gland cells ofChironomus thummi, the existing puffs in the giant chromosomes are enlarged. Autoradiography shows an increase in RNA synthesis of approximately 3-fold in these puffs. It is argued that histones in puffed chromosome segments are in a structural state that renders them unable to prevent RNA synthesis and at the same time causes them to be attacked earlier by trypsin.     

Localization of the exogenous fluorescent histones in Ehrlich Ascites tumour cells

Résumé Les auteurs ont étudié la localisation des histones fluorescents dans des cellules tumereuses d'ascites Ehrlich soumises à l'incubation in vitro avec les dérivés fluorescents de l'histone de thymus bovin ou avec quelques fractions du même histone. Ils ont démontré qu'après une incubation de courte durée les histones ont été adsorbés sur la surface des cellules, tandis que lors d'une incubation de longue durée les histones ont réussi à pénétrer dans les cellules.     

Chromatin circles in amphibian previtellogenic oocytes

Summary Previtellogenic oocytes ofOdontophrynus americanus display hundreds of chromatin circles. Electron microscopy of spread preparations of isolated nuclei shows that the circles originate from the chromatin. The circles change their morphology and form new copies. The length of the DNA packed in the nucleosomal circles is about 2.5–3.5 m or multiples of this value. Assuming that histones need not be removed from chromatin before DNA replication³ we suggest that the circles might belong to the process of rDNA amplification.This work was supported by grants from the Brazilian CNPq, FAPESP and FEDIB.We thank Dr A. Brunner Jr for the use of the electron microscope and Dr N. Leon for his valuable help.     

Antimicrobial activity in the skin of the channel catfish Ictalurus punctatus: characterization of broad-spectrum histone-like antimicrobial proteins

Three antibacterial proteins were isolated from acid extracts of channel catfish (Ictalurus punctatus) skin by cation exchange chromatography and reverse-phase high-pressure liquid chromatography. The molecular masses of the proteins were 15.5, 15.5 and 30 kD as determined by SDS-polyacrylamide gel electrophoresis. Mass spectrometry, amino acid composition and amino acid sequence data suggest that the most abundant protein is closely related to histone H2B. The H2B-like protein was inhibitory to Aeromonas hydrophila and Saprolegnia spp., which are important bacterial and fungal pathogens of fish. These findings suggest that histones may be important defensive molecules in fish. Received 22 December 1997; received after revision 5 March 1998; accepted 5 March 1998     

Application de méthodes d'analyse biochimique à une étude taxonomique: les corégones du lac de Neuchâtel

Summary Two closely related forms ofCoregonus from Lake Neuchatel were examined cytologically and biochemically, in order to ascertain the chromosome number and the DNA content of haploid and diploid nuclei.Coregonus fera has 2N=78 ± 2 chromosomes, and a DNA content (diploid) of 5.8 × 10⁻⁹ mg;Coregonus macrophthalmus, 2N=78⁺ ± 3, DNA content of 6.1 × 10⁻⁹ mg. The difference between the two DNA constants is statistically significant. These results do not support the hypothesis which postulates that polyploidy may be a determining factor in the speciation of these fishes.      

Uptake of labelled histones by isolated perfused rat liver and by various organs of the intact mouse

Résumé Des histones marquées au H³ ont été administrées à des souris par voie intrapéritonéale. La pénétration d'histones dans le foie isolé en perfusion est rapide. Les noyaux contiennent une quantité plus ou moins proportionnelle à leur volume dans la cellule et la majorité de l'activité a pu être isolée comme histones liées à la chromatine.     

Agglutininbildung durch verschiedene Proteinfraktionen vonSalmonella ballerup

Summary The author has examined the agglutinogenic property of nucleoprotein and its components, the nucleic acid and proteins fromS. ballerup. The nucleoprotein was obtained by the extraction of fresh bacteria desintegrated by means of glass powder at pH 8.4 and precipitated with acetic acid at pH 4.6, and its components by splitting the nucleoprotein with 0.5% sodium carbonate at pH 5.5. The protein component was separated from the nucleic acid by forming a chloroform-proteingel. The protein component was submitted to a further purification by dissolving at pH 7 and precipitating at pH 5.5. Rabbits to whom 4–8 mg of the substance were given in 10–12 doses were used for the immunization. The agglutinins were determined byHeidelberger andKabat's quantitative method with aS. ballerup suspension. The maximum quantity of agglutinin is shown in mg nitrogen per 1 cm³ of serum. In comparison with the results obtained by the immunization with whole germs, it follows that, by means of nitrogen compounds, the nucleoprotein has the most substantial agglutinogenic effect, and the nucleic acid the poorest one.     

SET domain protein lysine methyltransferases: Structure, specificity and catalysis

Site- and state-specific lysine methylation of histones is catalyzed by a family of proteins that contain the evolutionarily conserved SET domain and plays a fundamental role in epigenetic regulation of gene activation and silencing in all eukaryotes. The recently determined three-dimensional structures of the SET domains from chromosomal proteins reveal that the core SET domain structure contains a two-domain architecture, consisting of a conserved anti-parallel β-barrel and a structurally variable insert that surround a unusual knot-like structure that comprises the enzyme active site. These structures of the SET domains, either in the free state or when bound to cofactor S-adenosyl-L-homocysteine and/or histone peptide, mimicking an enzyme/cofactor/substrate complex, further yield the structural insights into the molecular basis of the substrate specificity, methylation multiplicity and the catalytic mechanism of histone lysine methylation. Received 10 June 2006; accepted 22 August 2006