Characterization of products derived from self-splicing of intron aI5 alpha which is located in the mitochondrial COX I gene of Saccharomyces cerevisiae.

We have characterized the in vitro self-splicing of intron aI5 alpha containing precursor RNA from the yeast mitochondrial gene coding for cytochrome oxidase subunit I. This intron follows the rules for group I self-splicing introns and all the characteristic products have been identified. In addition we have detected abnormal RNA products with features that indicate that the self-splicing behaviour of this intron is more complex.

Cell-free translation of human lysosomal alpha-glucosidase: evidence for reduced precursor synthesis in an adult patient with glycogenosis type II.

Early events in the biosynthesis of alpha-glucosidase (EC 3.2.1.

Behavior of dentists and child patients during treatment.

This study is part of a larger research project which aims to analyze children's dental fear by making a detailed analysis of the behavioral interactions between dentists and anxious child patients. The behavior of 12 high- and 12 low-anxious children was recorded on videotape during two dental visits in which the children were treated by either experienced or inexperienced dentists. Results indicated a relation between the dentist's experience in treating anxious children and the behavior of child patients.

Interactions between dentists and anxious child patients: a behavioral analysis.

The aim of this investigation was to study the effect of dentists' behavior on the (anxious) behavior of child patients. Twelve high-anxious and a matched group of 12 low-anxious children from 6 to 12 yr of age were selected and randomly assigned to one of six dentists: three with experience in treating fearful children and three without such experience. Each child was treated twice.

Effect of point mutations on in vitro transcription from the promoter for the large ribosomal RNA gene of yeast mitochondria.

Initiation of transcription on mitochondrial DNA of Saccharomyces cerevisiae was studied in an in vitro system with a mtRNA polymerase fraction reconstituted from separately purified components and with DNA templates containing the promoter of the gene coding for large rRNA. The effect of various point mutations in this promoter region was quantitated in assays containing a wildtype promoter in equimolar amount as internal control. Despite the strong conservation around the position at which RNA initiation occurs (ATATAAGTApuTA, initiation nucleotide underlined), none of the single point mutations abolished transcription-initiation completely.

New RNA-mediated reactions by yeast mitochondrial group I introns.

The group I self-splicing reaction is initiated by attack of a guanosine nucleotide at the 5' splice site of intron-containing precursor RNA. When precursor RNA containing a yeast mitochondrial group I intron is incubated in vitro under conditions of self-splicing, guanosine nucleotide attack can also occur at other positions: (i) the 3' splice site, resulting in formation of a 3' exon carrying an extra added guanosine nucleotide at its 5' end; (ii) the first phosphodiester bond in precursor RNA synthesized from the SP6 bacteriophage promoter, leading to substitution of the first 5'-guanosine by a guanosine nucleotide from the reaction mixture; (iii) the first phosphodiester bond in already excised intron RNA, resulting in exchange of the 5' terminal guanosine nucleotide for a guanosine nucleotide from the reaction mixture. An identical sequence motif (5'-GAA-3') occurs at the 3' splice site, the 5' end of SP6 precursor RNA and at the 5' end of excised intron RNA.

Advertising in dentistry.

Due to a rapid increase of unemployment among dentists in many countries, the interest in advertising as a means of stimulating the demand for dental care is increasing. In some countries (i.e.

Phaseolus vulgaris leuco-agglutinin tracing of intrahypothalamic connections of the lateral, ventromedial, dorsomedial and paraventricular hypothalamic nuclei in the rat.

Intrahypothalamic connections of the lateral (LHA), ventromedial (VMH), dorsomedial (DMH) and paraventricular (PVN) hypothalamic nuclei were studied with anterograde transport of iontophoretically injected Phaseolus vulgaris leuco-agglutinin and the immunocytochemical detection of labeled structures. The LHA was found to give rise to a minor projection in the VMH, whereas the VMH in reverse maintains few connections with the ventromedial part of the tuberal LHA. Tracer deposits in both the LHA and VMH resulted in anterograde terminal labeling in the DMH.

Interlocked RNA circle formation by a self-splicing yeast mitochondrial group I intron.

RNA containing the aI3 group I intron of the yeast mitochondrial gene encoding cytochrome oxidase subunit I shows self-splicing in vitro. The excised intron, comprising 1514 nucleotides, is partially split into an upstream portion, containing the intronic reading frame, and a downstream portion, containing the typical group I conserved sequence elements. Full-length intron RNA and intron parts occur in linear and circular form.

Characterization of the promoter of the large ribosomal RNA gene in yeast mitochondria and separation of mitochondrial RNA polymerase into two different functional components.

We have characterized a DNA sequence that functions in recognition of the promoter of the mitochondrial large rRNA gene by the yeast mtRNA polymerase. Promoter-containing DNA fragments were mutagenized and used as templates to study initiation of transcription in vitro with a partially purified mtRNA polymerase preparation. Deletion mutants, in which increasing stretches of DNA were removed from regions flanking the promoter, define a short area essential for correct initiation of transcription.

The projections of the dorsomedial hypothalamic nucleus in the rat.

The dorsomedial hypothalamic nucleus (DMH) output pathways are revealed by using autoradiographic tracing of tritium labeled Leucine and by the recently introduced Phaseolus vulgaris leuco-agglutinin immunocytochemical method. Terminal labeling appears in the dorsal motor nucleus of the vagus, nucleus ambiguus and in the parvocellular reticular formation at the lower medullary level. Mesencephalic labeling is found in the periaqueductal gray at the level of the oculomotor nucleus.

Formation of lariats and circles in self-splicing of the precursor to the large ribosomal RNA of yeast mitochondria.

Self-splicing of the precursor to large ribosomal RNA of yeast mitochondria leads not only to circles but also to lariats, structures that have not been observed before as products of self-splicing. Lariats were studied by electron microscopy after hybridization with an RNA complementary to the 3' half of the precursor. This leads to differentiation in at least two classes of lariats that vary in the position of the branch point.

Excised group II introns in yeast mitochondria are lariats and can be formed by self-splicing in vitro.

Excised group II introns in yeast mitochondria appear as covalently closed circles under the electron microscope. We show that these circular molecules are branched and resemble the lariats arising through splicing of nuclear pre-mRNAs in yeast and higher eukaryotes. One member of this intron class (aI5c in the gene for cytochrome c oxidase subunit I) is capable of self-splicing in vitro, giving correct exon-exon ligation and resulting in the appearance of both linear and lariat forms of the excised intron.

Respiratory physiology of fish, amphibian, and mammalian sperm.

Teleost (Liza dumerili) and toad (Xenopus laevis) sperm consume oxygen optimally at high oxygen tensions (120-150 mm Hg) close to the saturation level of the diluents. Oxygen consumption of sperm of both species declines rapidly below a pO2 of 60 mm Hg. Sperm of both species consume more oxygen per unit sperm in dilute than in dense sperm suspensions and conform to the so-called respiratory dilution effect.

Sperm swimming velocity as evaluated by frame lapse videography and computer analysis.

A videographic method is described to measure the swimming velocity of fresh human, frozen-thawed bull and white mussel (Donax serra) sperm. The method can be accurately controlled. The pattern of sperm movement can be analyzed on a frame-by-frame basis or over 0.

Autonomic innervation of the pancreas in diabetic and non-diabetic rats. A new view on intramural sympathetic structural organization.

Using histochemical and immunocytochemical methods the intramural neural tissue of the pancreas was investigated in non-diabetic and in alloxan-diabetic rats. It was demonstrated that the non-diabetic pancreas contains an average of 2.71 cells/mm3 tissue that react positive for activity of acetylcholinesterase and 2.