Duplication and remoulding of tRNA genes during the evolutionary rearrangement of mitochondrial genomes

During the evolution of sea urchins, a transfer RNA gene lost its tRNA function and became part of a protein-coding gene. This functional loss of a tRNA with specificity for one group of leucine codons (CUN, where N is any base) was accompanied by the gain of a new tRNA with that specificity. The new tRNA gene for CUN codons appears to have evolved by duplication and divergence from a tRNA gene specific for another group of leucine codons (UUR, where R is a purine). These proposals account for (1) the strong sequence resemblance between the modern tRNA genes for CUN and UUR codons in Paracentrotus, (2) the altered location of the CUN gene in mitochondrial DNA of this urchin, and (3) the persistence of a 72-base pair sequence containing a trace of the old CUN gene at its original location. The old CUN gene now codes for an extra 24 amino acids at the amino end of subunit 5 in NADH dehydrogenase. Besides giving clues about the mechanisms by which tRNA genes move during mitochondrial DNA evolution, this finding leads us to propose a pathway relating the arrangements of other genes in mitochondrial DNAs from four animal phyla.     

Control of malarial invasion by phosphorylation of the host cell membrane cytoskeleton

It has been shown that the entry of the malaria parasite into the red blood cell requires the presence of ATP in the host cell cytoplasm. In red blood cell ghosts that contain no ATP the receptor on the extracellular surface remains in place and parasites will bind to the membrane, but will not enter. ATP is thus necessary for one of the steps in the invasion sequence that follows recognition and attachment. The process of entry appears to involve the active participation of the host cell membrane cytoskeleton. We have suggested that the function of the intracellular ATP may be to regulate phosphorylation of the cytoskeleton. We now present evidence that the activity of the membrane-associated cyclic AMP-independent kinase of the red blood cell is inseparable from invasion; the active substrate may be spectrin.     

Determination of mass spectra of non-volatile substances

Zusammenfassung Ein einfaches Glas-Einlass-System wird beschrieben, das die direkte Einführung von organischen Substanzen in die Ionisationskammer eines Massenspek trometers gestattet. Es ist somit möglich Massenspektren von Substanzen zu bestimmen die man bisher nicht aufnehmen konnte. Beispiele werden angeführt.

---

---

This paper represents part XXII in the seriesMass Spectrometry in Structural and Stereochemical Problems. For preceding article, seeE. Lund, H. Budzikiewicz, J. M. Wilson, andC. Djerassi, J. Amer. Chem. Soc., in press.     

21世纪的艺术博物馆管理员

随着21世纪的到来，博物馆管理员们也不得不面对很多新的问题，他们需要了解信息技术的发展，需要跟上时代的步伐。本书中收录的若干文章着重讨论了有关博物馆管理员今天所面临的问题。     

Superior cervical ganglionectomy in the Japanese quail

Résumé Les effets de l'ablation des ganglions cervicals supérieurs deCoturnix coturnix japonica font l'objet de cet exposé. Chez le mâle la gangliectomie bilatérale n'affecte pas l'activité testiculaire. Par contre chez les femelles la quantité d'ufs pondus est nettement réduite et l'interruption post-opératoire de la pondaison est prolongée; de plus la première ponte des jeunes femelles est retardée. LesCoturnix qui ont subi l'ablation des ganglions ont un taux de mortalité plus élevé lorsque les oiseaux sont exposés à des abaissements de température et des changements de photopériodisme.

---

---

This work was supported in part by USPHS research grant No. NB 04171-83 and by NASA research grant No. NGR 05-004-028.