Identifying individuals by sequencing mitochondrial DNA from teeth.

Mitochondrial DNA (mtDNA) was extracted from teeth stored from 3 months to 20 years, including teeth from the semi-skeletonized remains of a murder victim which had been buried for 10 months. Tooth donors and/or their maternal relatives provided blood or buccal cells, from which mtDNA was also extracted. Enzymatic amplification and direct sequencing of roughly 650 nucleotides from two highly polymorphic regions of mtDNA yielded identical sequences for each comparison of tooth and fresh DNA. Our results suggest that teeth provide an excellent source for high molecular weight mtDNA that can be valuable for extending the time in which decomposed human remains can be genetically identified.     

Afferent respiratory pathways in the avian vagus

Résumé Nous avons enregistré 88 afférences respiratoires du nerf vague chez le poulet. Quelques unes se déclenchaient au cours de l'inspiration eupnéique, d'autres au cours de l'expiration. Jusqu'à présent, on a l'impression qu'il existe plus de types d'activité afférente respiratoire chez l'oiseau que chez le mammifère, mais de nouvelles analyses seront nécessaires pour mieux les préciser. Nous croyons que c'est ici la première preuve évidente de l'existence d'un contrôle afférent vagal de la respiration chez l'oiseau.

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This work was supported by a grant from the British Egg Marketing Board.     

Effect of trifluoperazine and calcium ions on gregarine gliding

Summary The drug trifluoperazine (TFP) inhibits the gliding motility of gregarine protozoans. This suggests that the Ca⁺⁺ binding protein, calmodulin, plays a role in the motility process. However the presence of extracellular Ca⁺⁺ was not required for gliding to occur.Acknowledgments. We should like to thank L. Cooper for technical assistance, Smith, Kline and French for the gift of trifluoperazine, and Terry Preston for valuable discussion.     

The influence of early nutrition and environmental rearing on brain growth and behaviour

Summary Preweaning malnutrition permanently reduced brain size and cellular content but in spite of changes in the adrenocortical stress response no learning deficit was observed. Differential rearing environments did not influence the effects of malnutrition.This work was supported by a grant from the National Health and Medical Research Council of Australia.We thank Mrs.Jean Williams andDr. A. Miller, Department Maths. Stats., C. S. I. R. O., Sydney for assistance with the statistical analysis.     

Upper intestinal lipids trigger a gut-brain-liver axis to regulate glucose production

Energy and glucose homeostasis are regulated by food intake and liver glucose production, respectively. The upper intestine has a critical role in nutrient digestion and absorption. However, studies indicate that upper intestinal lipids inhibit food intake as well in rodents and humans by the activation of an intestine-brain axis. In parallel, a brain-liver axis has recently been proposed to detect blood lipids to inhibit glucose production in rodents. Thus, we tested the hypothesis that upper intestinal lipids activate an intestine-brain-liver neural axis to regulate glucose homeostasis. Here we demonstrate that direct administration of lipids into the upper intestine increased upper intestinal long-chain fatty acyl-coenzyme A (LCFA-CoA) levels and suppressed glucose production. Co-infusion of the acyl-CoA synthase inhibitor triacsin C or the anaesthetic tetracaine with duodenal lipids abolished the inhibition of glucose production, indicating that upper intestinal LCFA-CoAs regulate glucose production in the preabsorptive state. Subdiaphragmatic vagotomy or gut vagal deafferentation interrupts the neural connection between the gut and the brain, and blocks the ability of upper intestinal lipids to inhibit glucose production. Direct administration of the N-methyl-d-aspartate ion channel blocker MK-801 into the fourth ventricle or the nucleus of the solitary tract where gut sensory fibres terminate abolished the upper-intestinal-lipid-induced inhibition of glucose production. Finally, hepatic vagotomy negated the inhibitory effects of upper intestinal lipids on glucose production. These findings indicate that upper intestinal lipids activate an intestine-brain-liver neural axis to inhibit glucose production, and thereby reveal a previously unappreciated pathway that regulates glucose homeostasis.     

A simple interspike interval analyzer for study of neuronal spike trains

Summary A simple, low cost interspike interval analyzer for the analysis of trains of nerve impulses is described. The analyzer is built with readily available integrated circuits and has been used to analyze spike trains in the lateral vestibular nucleus of cats.Acknowledgment. This research is supported in part by Higher Degrees and Research Grant No. 158/363 to J.C.H. from the University of Hong Kong.