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Biomedical subjects

R W Riess

Publications and source records attributed to R W Riess.

5 recordsLinked to original sources
PubMed1991

Synaptonemal complex behavior in asynaptic maize.

Synatonemal complexes were studied in silver-stained spread preparations of microsporocyte complements of asynaptic maize. Complexes were found predominantly in terminal regions of chromosome pairs. These tend to be aggregated in a common portion of the nucleus and to have polar orientation. As many as 19 of the 20 ends were found to be involved in relatively short paired segments. Intercalary regions of cores were not strongly organized and aligned, but some contained completed synaptonemal complex segments. The defect in asynaptic appears to represent stalling of the synaptic process at an early stage of synaptic progression.

Microscopy, Electron↗
PubMed1991

The desynaptic mutant of maize as a combined defect of synaptonemal complex and chiasma maintenance.

The phenotype of the desynaptic (dy) mutant of maize in microsporocytes at meiotic prophase was compared with normal microsporocytes of a closely related strain and with microsporocytes of a maize inbred line (KYS) assumed to be normal. Strikingly more univalents and open arms of bivalents were found in the mutant cells than in normal cells at diakinesis, and where there was heterozygosity for a distal knob (heterochromatic region), separation was usually equational, indicating the occurrence of normal crossing-over followed by failure of chiasma maintenance in the mutant. Differences found in the mutant by electron microscopy were a statistically significant wider dimension of the synaptonemal complex central region and also less twisting of synapsed configurations at pachytene. It is suggested that these are side-effect symptoms of a defect in the synaptonemal complex (or associated substance), which is expressed later as sporadic loss of chiasma maintenance.

Microscopy, Electron↗
PubMed1978

The sperm and its formation in the scorpion Centruroides vittatus.

The development of sperm from a spermatid in the scorpion, Centruroides vittatus (Say), is described. The mature sperm is short with helical nucleus and a peculiar structure of the sperm tail. This peculiarity consists of alternating mitochondrial derivatives and membranous or network elements wrapped about the flagellum. We note the absence both of microtubules in the sperm of Centruroides and also of the centriole adjunct, which is present in other scorpion spermatids.

Animals↗