A simple one-step procedure for staining the nucleolus organizer regions.

A simple silver staining technique for routine use is described by which the nucleolus organizer regions of mammalian chromosomes, including those of mouse chromosomes, are stained selectively.     

Variable positions of nucleolus organizer regions in Bovidae

Summary Silver NOR staining has been applied to cattle (Bos taurus L.), goat (Capra hircus L.) and sheep (Ovis aries L.) chromosomes. The sites of silver NORs showed variation within the family Bovidae probably due to a reciprocal translocation event.     

Ultrastructural identification of the nucleolus organizer by the silver staining technic]

The nucleolus organizer regions can be selectively stained in metaphase chromosome preparations by the Goodpasture and Bloom's technique which was adapted to electron microscopy analysis of cells during interphase. Using this technique, a selective accumulation of silver grains was observed over nucleolus light areas. This selective accumulation allows the identification of the interphase fibrillar centers as the nucleolus organizer regions. Ultrastructural relationships between fibrillar centers and dense fibrillar component are discussed.     

Controlled silver-staining of nucleolus organizer regions with a protective colloidal developer: a 1-step method

Summary A 1-step silver-staining technique, requiring only 2 min to perform, is described for the differential staining of nucleolus organizer regions. A protective colloidal developer is used to control the reduction of the silver.This research was supported by the National Science Foundation, grant Nos PCM-76-82828 and DEB-76-84195 to WMH.     

Controlled silver-staining of nucleolus organizer regions with a protective colloidal developer: a 1-step method

A 1-step silver-staining technique, requiring only 2 min to perform, is described for the differential staining of nucleolus organizer regions. A protective colloidal developer is used to control the reduction of the silver.     

Detection of nucleolus organizer regions (NOR) in the chromosomes of the domestic pig (Sus scrofa domestica L.)

Summary In the domestic pig (Sus scrofa domestica L.) nucleolar organizer regions (NOR) were detected by a combined silver-Giemsa method (Ag-G). The main sites of NORs are the secondary constrictions of chromosomes 8 and 10. Sometimes an additional NOR was observed near the centromere of 1 homologue of chromosome 11. Associations of NORs were seen only between chromosomes 10 and at a very low frequency.     

Detection of nucleolus organizer regions (NOR) in the chromosomes of the domestic pig (Sus scrofa domestica L.)

In the domestic pig (Sus scrofa domestica L.) nucleolar organizer regions (NOR) were detected by a combined silver-Giemsa method (Ag-G). The main sites of NORs are the secondary constrictions of chromosomes 8 and 10. Sometimes an additional NOR was observed near the centromere of 1 homologue of chromosome 11. Association of NORs were seen only between chromosomes 10 and at a very low frequency.     

A simple staining technique for electron microscopy with lead-uranyl acetate

Resumen Mediante el empleo de una solución saturada de acetato de uranilo-plomo en acetona de 70%, durante el proceso convencional de deshidratación, se ha conseguido incrementar marcadamente el contraste electrónico en ápices radicales dePhalaris canariensis, sin riesgo alguno de contaminación o deformación de las estructuras.     

A simple staining technique to demonstrate chromosomal DNA replication

Summary With the BrdU technique here described, Giemsa stained metaphases with either early or late, replicational patterns can be obtained within 1 day after cell harvesting, showing a better resolution than³H-thymidine autoradiography.     

Constitutive heterochromatin and nucleolus organizer region in the knifefish,Apteronotus albifrons (Pisces,Apteronotidae)

Summary The C-banding and silver staining of the chromosomes of the knifefishApteronotus albifrons (2n=24), demonstrated the presence of constitutive heterochromatin in the centromeric region of every chromosome, except pair 4, where the entire long arm was darkly stained, the silver stain positive nucleolus organizer region (NOR) being embedded in it.The authors are grateful to Dr Sen Pathak (University of Texas System Cancer Center at Houston, Texas, USA) and Dr Yatiyo Yassuda (Universidade de São Paulo, São Paulo, Brasil) for their suggestions. This study was supported in part by grants of the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq).     

A simple staining technique to demonstrate chromosomal DNA replication.

With the BrdU technique here described, Giemsa stained metaphases with either early or late replicational patterns can be obtained within 1 day after cell harvesting, showing a better resolution than 3H-thymidine autoradiography.     

A simple device for measurement of circular dichroism in the visible and ultraviolet regions

Zusammenfassung Es wird ein einfacher Apparat beschrieben, der als Zusatzgerät zum. Zeiss-Spektralphotometer PMQ II zur Messung von Zirkulardichroismus zu verwenden ist.     

Cytological evidence on the ability of the nucleolus organizing regions to assemble pre-existing nucleolar material

Summary The treatment ofVicia faba root tips with 5-azacytidine caused unequal allotment of the chromosomes; after one cell cycle, a pair of daughter nuclei was produced, one of which carried the nucleolus organizing regions (NORs) and the other of which lacked them. The pre-existing nucleolar material brought into the NOR-carrying daughter nucleus by the chromosomes disappeared concurrently with the appearance of the new nucleoli, whereas in another daughter nucleus without the NOR a number of small nucleolus-like bodies became visible at random positions. These findings suggest that in addition to ribosomal RNA synthesis the NOR has another role in cells; to stimulate the pre-existing nucleolar material to assemble at the NOR itself.