Purification, sequencing and synthesis of natriuretic and vasoactive rat atrial peptide

Mammalian atria contain potent natriuretic and diuretic substances which exist in high- and low-molecular-weight forms and which appear to be associated with atrium-specific granules. The natriuretic effect of atrial extract is largely accountable for by its renal haemodynamic effects; atrial extracts also antagonize hormone- and non-hormone-induced contraction of the isolated rabbit aorta and isolated rat kidney vasculature. We have completely purified a low-molecular-weight natriuretic and vasoactive substance from rat atria and characterized it as a 24-amino acid peptide. Synthetic peptide, produced by solid-phase synthesis, mimics biological effects of crude atrial extract and purified peptide; its activity is enhanced by slow oxidation, suggesting a disulphide (Cys 4-Cys 20) configuration for the native peptide. If secreted into blood, this atrial natriuretic peptide (' auriculin B') could be a novel peptide hormone of considerable importance to renal and cardiovascular homeostasis.     

Alternative methods of animal sacrifice: The effect on intestinal function in vitro

Summary The total fluid uptake of everted sacs of rat jejunum was compared in animals killed by stunning and decapitation, or anaesthetised with ether. Fluid transport was significantly higher in the tissue prepared from stunned and decapitated animals. It is suggested that etherization may have adverse effects on the physiological viability of subsequently isolated tissues.     

Apparent delayed enhancement of memory following post-trial methylamphetamine hydrochloride

Résumé L'hydrochlorure de méthylamphétamine, drogue qui était administrée aux rats après qu'ils aient subi une seule expérience d'entrainement, améliorerait la mémoire des animaux testés, mais cet effet se n'est produit que 7 jours après l'expérience.     

A stress-sensitive reporter predicts longevity in isogenic populations of Caenorhabditis elegans

When both genotype and environment are held constant, 'chance' variation in the lifespan of individuals in a population is still quite large. Using isogenic populations of the nematode Caenorhabditis elegans, we show that, on the first day of adult life, chance variation in the level of induction of a green fluorescent protein (GFP) reporter coupled to a promoter from the gene hsp-16.2 predicts as much as a fourfold variation in subsequent survival. The same reporter is also a predictor of ability to withstand a subsequent lethal thermal stress. The level of induction of GFP is not heritable, and GFP expression levels in other reporter constructs are not associated with differences in longevity. HSP-16.2 itself is probably not responsible for the observed differences in survival but instead probably reflects a hidden, heterogeneous, but now quantifiable, physiological state that dictates the ability of an organism to deal with the rigors of living.     

The Ter mutation in the dead end gene causes germ cell loss and testicular germ cell tumours

In mice, the Ter mutation causes primordial germ cell (PGC) loss in all genetic backgrounds. Ter is also a potent modifier of spontaneous testicular germ cell tumour (TGCT) susceptibility in the 129 family of inbred strains, and markedly increases TGCT incidence in 129-Ter/Ter males. In 129-Ter/Ter mice, some of the remaining PGCs transform into undifferentiated pluripotent embryonal carcinoma cells, and after birth differentiate into various cells and tissues that compose TGCTs. Here, we report the positional cloning of Ter, revealing a point mutation that introduces a termination codon in the mouse orthologue (Dnd1) of the zebrafish dead end (dnd) gene. PGC deficiency is corrected both with bacterial artificial chromosomes that contain Dnd1 and with a Dnd1-encoding transgene. Dnd1 is expressed in fetal gonads during the critical period when TGCTs originate. DND1 has an RNA recognition motif and is most similar to the apobec complementation factor, a component of the cytidine to uridine RNA-editing complex. These results suggest that Ter may adversely affect essential aspects of RNA biology during PGC development. DND1 is the first protein known to have an RNA recognition motif directly implicated as a heritable cause of spontaneous tumorigenesis. TGCT development in the 129-Ter mouse strain models paediatric TGCT in humans. This work will have important implications for our understanding of the genetic control of TGCT pathogenesis and PGC biology.