Intranuclear crystalloids in arcuate nucleus neurons after clomiphene citrate administration

Summary The action of high doses of clomiphene citrate on the nuclei of hypothalamic arcuate neurons of male cats has been studied. Clomiphene produces an accumulation of typical crystalloid material in the nuclei. After administration of a protein-synthesis inhibitor, no such material was observed in clomiphene-treated animals.These ultrastructural features could possibly be due to a more intense protein synthesis in the hypothalamic arcuate neurons.     

The General Concept of Antinomicity

Antinomicity is not necessarily dependent on negation; there is a more general conception of antinomicity based on the fundamental idea of opposition. To study this fact is indispensable to show first that truth and falsity are independent of assertion and negation. Then it can be seen that antinomies can be found everywhere, and that some single categories are in intrinsic opposition with themselves while others are opposed to one another in pairs. An antinomic ‘manifesto’ concludes the work. This revised version was published online in July 2006 with corrections to the Cover Date.     

Rational design of carbon shell-encapsulated cobalt nanospheres to enhance microwave absorption performance

Co@C core–shell nanospheres highly dispersed on carbon supports were rationally designed to improve the microwave absorbing property of the composite material, and fabricated by one pot thermal decomposition and simple annealing process. The Co nanospheres were completely encapsulated with thin carbon shells, which can effectively prevent the oxidation of the Co surface. Additionally, the particle size of Co nanospheres were properly controlled to optimize the electromagnetic property of the composite material. As a result, the lightweight Co@C/C composites with the particle size of 20 nm exhibited much enhanced microwave absorption properties. The improved microwave absorption performance is attributed mainly to the enhanced isotropic ratio and impedance matching of magnetic composites via tuning the Co particle size. Therefore, the welldesigned core-shell Co@C composite structure will provide a new insight for the development of high performance microwave absorbers.     

A massive, cooling-flow-induced starburst in the core of a luminous cluster of galaxies

In the cores of some clusters of galaxies the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous 'cooling flows' of gas sinking towards the cluster centre, yet no such cooling flow has been observed. The low observed star-formation rates and cool gas masses for these 'cool-core' clusters suggest that much of the cooling must be offset by feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical and infrared observations of the galaxy cluster SPT-CLJ2344-4243 (ref. 11) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2?×?10(45)?erg?s(-1)) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers.     

Structure of eEF3 and the mechanism of transfer RNA release from the E-site

Elongation factor eEF3 is an ATPase that, in addition to the two canonical factors eEF1A and eEF2, serves an essential function in the translation cycle of fungi. eEF3 is required for the binding of the aminoacyl-tRNA-eEF1A-GTP ternary complex to the ribosomal A-site and has been suggested to facilitate the clearance of deacyl-tRNA from the E-site. Here we present the crystal structure of Saccharomyces cerevisiae eEF3, showing that it consists of an amino-terminal HEAT repeat domain, followed by a four-helix bundle and two ABC-type ATPase domains, with a chromodomain inserted in ABC2. Moreover, we present the cryo-electron microscopy structure of the ATP-bound form of eEF3 in complex with the post-translocational-state 80S ribosome from yeast. eEF3 uses an entirely new factor binding site near the ribosomal E-site, with the chromodomain likely to stabilize the ribosomal L1 stalk in an open conformation, thus allowing tRNA release.     

Horizontal endosymbiont transmission in hydrothermal vent tubeworms

Transmission of obligate bacterial symbionts between generations is vital for the survival of the host. Although the larvae of certain hydrothermal vent tubeworms (Vestimentifera, Siboglinidae) are symbiont-free and possess a transient digestive system, these structures are lost during development, resulting in adult animals that are nutritionally dependent on their bacterial symbionts. Thus, each generation of tubeworms must be newly colonized with its specific symbiont. Here we present a model for tubeworm symbiont acquisition and the development of the symbiont-housing organ, the trophosome. Our data indicate that the bacterial symbionts colonize the developing tube of the settled larvae and enter the host through the skin, a process that continues through the early juvenile stages during which the trophosome is established from mesodermal tissue. In later juvenile stages we observed massive apoptosis of host epidermis, muscles and undifferentiated mesodermal tissue, which was coincident with the cessation of the colonization process. Characterizing the symbiont transmission process in this finely tuned mutualistic symbiosis provides another model of symbiont acquisition and additional insights into underlying mechanisms common to both pathogenic infections and beneficial host-symbiont interactions.     

Ultrastructural evidence of a secretory process in the rat pineal gland.

Pericapillar spaces of the rat pineal gland belong to the most active sites of this organ. Neighborhood of sympathetic nerve endings, capillaries and pinealocyte processes facilitates possibly the synthesis and the secretion of methoxyindoles. Lipid droplets migrate through the pinealocyte cellular processes towards the terminal enlargement or poles, where they are secreted into the pericapillar space, and the possibility that indoleamines are included in the lipid droplets has been discussed.     

Lack of effect ofTris-(hydroxymethyl)aminomethane upon myocardial contractility

Résumé Pour étudier l'action du THAM sur la contractilité, dans une préparation de myocarde isolé, on a réalisé des expériences, où l'on compare l'effet de remplacer une solution de Ringer contenant 30 mM/l de CO₃HNa, équilibrée avec une pCO₂ de 40 mm Hg (pH 7,40), par une solution de THAM ayant le même pH avec le même pCO₂. Les résultats ont permis de conclure que le THAM n'a aucune influence inotrope positive sur la contractilité, lorsque le pH extracellulaire et le pCO₂ restent invariables.