Lisa Herickhoff

Staining Plant Cells with Silver. I. The Salt-Nylon Technique

A technique is described for selectively silver staining nucleoli, active nucleolus organizers, nucleolar material attached to chromosomes, kinetochores, synaptonemal complexes, and chromosome cores in plant cells. The technique, called salt-nylon silver staining, involves spreading cells on glass slides, treating the cells with a solution of saline sodium citrate, and incubating the cells in a silver nitrate solution covered with nylon screen. Selected variables important for achieving reliable silver staining are considered.

The relationship between synapsis, recombination nodules and chiasmata in tomato translocation heterozygotes

Spreads of synaptonemal complexes (SCs) were made from five different reciprocal translocation heterozygotes in tomato (Lycopersicon esculentum). Patterns of synapsis and distribution of recombination nodules (RNs) and chiasmata were analysed. Translocated chromosomes usually synapsed to form quadrivalents. By measuring the length of synapsed arms, we estimated the positions of the breaks for translocations 2-10b (both breaks in euchromatin), 9-12 (both breaks in heterochromatin), and 2-10a, 1-3 and 1-12 (one break in euchromatin and one break in heterochromatin). The distribution of RNs indicates that interference occurs within arms of quadrivalents. If interference occurs between arms it is transferred to opposite and adjacent arms equally. We found no significant difference between the distribution of RNs and chiasmata. These results support a one RN: one crossover: one chiasma relationship.

Staining Plant Cells with Silver. III. The Mechanism

Silver does not stain all cytological structures with the same intensity. The chemical basis for differential silver staining is unclear, but differences in protein side groups available to react with silver are likely involved. These include amine, carboxyl, phosphate, sulfhydryl and hydroxyl moieties. Here we report an investigation of the chemical groups that could be involved in salt-nylon silver staining of onion root tip squashes. Based on the results, we conclude that SN silver staining primarily depends on the presence of tyrosine hydroxyl groups, and we propose a mechanism for staining.