Barley leaf unrolling. The proline connection

Unrolling of 1 cm sections, taken between 3 and 4 cm from the apex, of 6-day-old, etiolated barley leaves, was promoted by blue (426 nm) and red (658 nm) light. Accompanying such unrolling was a reduction in the level of the free proline of the tissue. When leaf unrolling was prevented by irradiation with far-red (728 nm) light, or treatment with abscisic acid (ABA) following red light irradiation, the level of proline remained more or less unchanged, at the level of the untreated, dark controls. The proline analogue, azetidine carboxylic acid (AZC) powerfully inhibited the light induced leaf opening, emphasizing the significance of proline-containing, structural and functional proteins in barley leaf unrolling. The inhibition imposed by AZC is partially reversible by added proline.     

Onset of nucleolus organizer activity in early mouse embryogenesis and evidence for its regulation

Ovulated mouse oocytes and preimplantation embryos were examined for NOR activity by means of selective silver staining. Evidence of the first staining activity appeared in two cell embryos, which was later followed by an increase in nucleolar activity, whereas the ovulated oocytes and pronuclei showed no such activity whatsoever. The staining of chromosomes was restricted to the nucleolus organizing region. Our results agree with earlier observations that genes for ribosomal RNA (rRNA) are transcribed as early as in the 2-cell stage in mouse embryogenesis. In addition to the nuclear staining we also observed some silver staining within the cytoplasm, at least from 4-cell stages onwards. Cytoplasmic staining was resistant to incubation with cycloheximide and actinomycin D. Nuclear staining was depressed, or even totally blocked, after actinomycin D incubation but was not blocked by cycloheximide. The onset of silver staining depends not on a specific embryonic stage but on the time interval following ovulation. This appears to indicate that the initiation of ribosomal cistrons is regulated by molecules which are activated or synthesized within the oocyte soon after ovulation.     

Fluorescence-microscopical demonstration of a population of gastro-intestinal nerve fibres with a selective affinity for Quinacrine

Summary A population of nerve fibres in the gastro-intestinal tract of mice showing a high affinity for quinacrine was revealed by fluorescence microscopy. Similar results were obtained in rats and guinea pigs. Whole-mounts of sheets of the smooth muscle layer following incubation in 10^-6-10^-7 M quinacrine for 15–60 min revealed fine fluorescent varicose nerve fibers in the myenteric plexus of Auerbach both around nerve cell bodies and in the interconnecting strands. Many fibers were also present between the strands of the plexus, especially running parallel to the circular muscle layer. Such fibers were not seen in similarly quinacrine-incubated irides. A proportion of the cell bodies in Auerbach's plexus also showed quinacrine accumulation. These cells were apparently smaller neurons, sometimes with fluorescent processes. Intraperitoneal injections of quinacrine failed to demonstrate nerve fibers, but some cell bodies in Auerbach's plexus were positive. Subsequent paraformaldehyde treatment for monoamine visualization showed persistent adrenergic nerve terminals in the intestine and iris. These nerves seemed to be fewer and had a more yellow fluorescence than normally. The identity of the quinacrine-positive fibers is discussed with respect to recent suggestions that purinergic, substance P, enkephalin, and somatosin-containing nerves, in addition to adrenergic and cholinergic nerves, are present in the gut wall.Supported by the Swedish Medical Research Council (04X-03185). Magnus Bergvalls Stiftelse and Karolinska Institutets Fonder. For generous gifts of Mepacrine we thank Winthrop, Skärholmen, Stockholm, Sweden. The skilful technical assistance of Miss Gerd Boetius and Miss Maud Eriksson is gratefully acknowledged     

GD (-) Aachen,a new variant of deficient glucose-6-phosphate dehydrogenase

Summary A deficient G-6PD variant was discovered in 4 males of one family from north-western Germany. Five generations of this family could be studied.The deficient G-6PD was a new variant, called Gd (-) Aachen. Its main characteristics are the following: severe enzyme deficiency in erythrocytes (3% of normal), contrasting with an almost normal activity in leukocytes; normal molecular specific activity (i.e., normal ratio enzyme activity/cross-reacting material); slow mobility in starch gel electrophoresis (92–94% of normal); increased Michaelis constant for glucose-6-phosphate (60–70 M) and NADP⁺ (20–25 M); decreased inhibition constant by NADPH with respect to NADP⁺ (7 M); increased inhibition by ATP; normal utilization of the substrate analogues; slightly biphasic pH curve; thermal instability, and normal activation energy of the enzymatic reaction.The relationships between the hematologic disorders (severe and frequent hemolytic crises) and the unfavorable kinetic modifications are discussed.with the technical assistance of Joelle Marie and Dominique CottreauDedicated to Prof. Dr. H. Schonenberg, Aachen, on his 60th birthday. The first results of this work were presented in part at the Kongress der Deutschen Kinderärzte, München.     

Calf articular cartilage in organ culture in a chemically defined medium

In Vitro Cellular &; Developmental Biology - Plant - Articular cartilage from 6-month-old calves was maintained in organ culture in Eagle's minimum essential medium at different oxygen...