The angle of cell division is critical in at least two contexts. It can determine cell fate, as it does in developing neural tissue. It can also dictate tissue architecture, as it does in many epithelia. One way to ensure the correct angle of cell division is through controlled orientation of the spindle at metaphase. What happens when that control is lost? Ongoing work suggests that the conseq...

For three species of grasshoppers the volumes of the largest and the smallest metaphase chromosome differ by a factor of 10, but the microtubules (MTs) attached to the individual kinetochores show no corresponding range in numbers. Locusta mitotic metaphase chromosomes range from 2 to 21 mum, and the average number of MTs per kinetochore is 21 with an SD of 4.6. Locusta meiotic bivalents at lat...

In Chinese hamster Don cells, fusion of an interphase cell with a metaphase cell resulted either in prophasing of the interphase nucleus, including loss of the nuclear envelope (NE), or in the formation of a double membrane around the metaphase chromosomes. Only one of these phenomena occurred in a given interphase-metaphase (I-M) binucleate cell. At pH 7.4, there was about an equal probability...

A simple and efficient method for the maintenance of Acheta domeslicus spermatocytes in vitro while permitting microscopic observation during meiotic maturation is described. The method allows the study of the factors effecting normal maturation and is applicable to other organisms. Three media are described: MM 100 contains only salts in the concentrations found in Acheta hemolymph; MMIOI cont...

Cotton is an economically important crop that needs more extensive genetic characterization. Highly effective methods for consistent cell cycle manipulation are needed to efficiently produce high quality cytological preparations of chromosomes, and to improve methods of chromosome doubling, both of which impact cotton genomics and breeding. This manuscript reports a procedure for cell cycle syn...

Strain LT/Sv female mice show a high frequency of spontaneous ovarian teratomas arising from parthenogenetically activated follicular oocytes. LT/Sv oocytes also arrest at metaphase of meiosis I, rather than progressing through to metaphase II, as do almost all fully grown oocytes from most other strains. We investigated a new set of recombinant inbred strains derived from BALB/c and C58 (the p...

In vertebrate unfertilized eggs, metaphase arrest in Meiosis II is mediated by an activity known as cytostatic factor (CSF). CSF arrest is dependent upon Mos-dependent activation of the MAPK/Rsk pathway, and Rsk activates the spindle checkpoint kinase Bub1, leading to inhibition of the anaphase-promoting complex (APC), an E3 ubiquitin ligase required for the metaphase/anaphase transition. Howev...

To obtain a better understanding of the relationship between metaphase chromosome banding patterns and genome organization, attention was focused on regions of metaphase chromosomes that were found to contain the genes for a specific cellular enzyme, dihydrofolate reductase (DHFR). These studies involved the use of highly methotrexate-resistant mouse lymphoblastoid cells (L5178YR), which contai...

The replication licensing factor (RLF) is an essential initiation factor that is involved in preventing re-replication of chromosomal DNA in a single cell cycle. In Xenopus egg extracts, it can be separated into two components: RLF-M, a complex of MCM/P1 polypeptides, and RLF-B, which is currently unpurified. In this paper we investigate variations in RLF activity throughout the cell cycle. Tot...

The authors developed an integrated computer-aided detection (CAD) scheme for detecting and classifying metaphase chromosomes as well as assessing its performance and robustness. This scheme includes an automatic metaphase-finding module and a karyotyping module and it was applied to a testing database with 200 digital microscopic images. The automatic metaphase-finding module detects analyzabl...