A preliminary study on habitat selection of the Japanese serow (Capricornis crispus) at two temporal scales,season and time of day,in a montane forest

Journal of Ethology - Habitat selection has a significant influence on animals’ fitness, and has been well studied in various ungulates. A trade-off between the access to forage and to...     

Visualization of individual DNA molecules in solution by light microscopy: DAPI staining method

A method was developed to visualize individual DNA molecules in solution under a fluorescent microscope connected to a highly sensitive video camera. DNA stained with a fluorescent dye, DAPI, revealed thin extended filaments, thicker filaments and rapidly transforming folded structures dependent upon the solution conditions. Structural transitions were observed and recorded as video images. Our observations indicated the possibility that DNA has the ability of supercoiling itself. This DAPI staining method will have wide possible application in the study of DNA and chromatin.     

Fission yeast Cut2 required for anaphase has two destruction boxes.

The fission yeast Schizosaccharomyces pombe cut2(+) gene is essential for sister chromatid separation. Cut2 protein, which locates in the interphase nucleus and along the metaphase spindle, disappears in anaphase with the same timing as mitotic cyclin destruction. This proteolysis depends on the APC (Anaphase-Promoting Complex)-cyclosome which contains ubiquitin ligase activity. The N-terminus of Cut2 contains two stretches similar to the mitotic cyclin destruction box. We show that both sequences (33RAPLGSTKQ and 52RTVLGGKST) serve as destruction boxes and are required for in vitro polyubiquitination and proteolysis. Cut2 with doubly mutated destruction boxes inhibits anaphase, whereas Cut2 with singly mutated boxes can suppress cut2 mutations. Strong expression of the N-terminal 73 residues containing the destruction boxes leads to the accumulation of endogenous cyclin and Cut2, and arrests cells in metaphase, whereas the same fragment with the mutated boxes does not. Cut2 proteolysis occurs in vitro using Xenopus mitotic extracts in the presence of functional destruction boxes. Furthermore, Cut2 is polyubiquitinated in an in vitro system using HeLa extracts, and this polyubiquitination requires the destruction boxes.     

Higher order chromosome structure is affected by cold-sensitive mutations in a Schizosaccharomyces pombe gene crm1+ which encodes a 115-kD protein preferentially localized in the nucleus and its periphery

We isolated a novel class of Schizosaccharomyces pombe cold-sensitive mutants with deformed nuclear chromosome domains consisting of thread- or rodlike condensed segments at restrictive temperature. Their mutations were mapped in a novel, identical locus designated crm1 (chromosomal region maintenance). The crm1 mutants also show the following phenotypes. DNA, RNA, and protein syntheses diminish at restrictive temperature. At permissive temperature, the amount of one particular protein, p25, greatly increases. The mutant growth is hypersensitive to Ca2+ and resistant to protein kinase inhibitors. We cloned the 4.1-kb-long crm1+ gene that rescued the above phenotypes by transformation and determined its nucleotide sequence, which predicts a 1,077-residue protein. Affinity-purified antiserum raised against the crm1+ polypeptide expressed in Escherichia coli detected a 115-kD protein in S. pombe extracts. Genomic Southern hybridization and immunoblotting suggested that the crm1+ product might be highly conserved in distant organisms. Through immunofluorescence microscopy, the crm1+ protein appeared to be principally localized within the nucleus and also at its periphery. We speculate that the crm1+ protein might be one of those nuclear components that modify the chromosome structures or regulate the nuclear environment required for maintaining higher order chromosome structures.     

Frontier questions about sister chromatid separation in anaphase

Sister chromatid separation in anaphase is an important event in the cell's transmission of genetic information to a descendent. It has been investigated from different aspects: cell cycle regulation, spindle and chromosome dynamics within the three-dimensional cell architecture, transmission fidelity control and cellular signaling. Integrated studies directed toward unified understanding are possible using multidisciplinary methods with model organisms. Ubiquitin-dependent proteolysis, protein dephosphorylation, an unknown function by the TPR repeat proteins, chromosome transport by microtubule-based motors and DNA topological change by DNA topoisomerase II are all necessary for progression from metaphase to anaphase. Chromosome condensation, mitotic kinetochore function and spindle formation require a large number of proteins, which are prerequisites for successful sister chromatid separation. Factors that help to retain sister chromatid connection after replication and prevent premature separation remain to be determined. Although sister chromatid separation occurs in anaphase, gene functions in other cell cycle stages also ensure the progression of correct chromatid separation.     

Calcium sulfate and calcium carbonate as root-knot-nematode attractants and possible trap materials to protect crop plants

Root-knot nematodes (RKNs, genus Meloidogyne) are a class of plant parasites that seek out and infect the roots of many plant species. The identification of RKN attractants can be used in agriculture in conjunction with nematode-trapping technology to redirect RKN movements and eventually reduce their prevalence in the field. Here, we discovered that some commercial silica gels can attract nematodes. Silica gels that attract nematodes contain calcium sulfate. Calcium sulfate and calcium carbonate showed strong nematode attraction properties. When plant seeds were surrounded by calcium sulfate or calcium carbonate, nematodes were not attracted to the plant seeds. We propose that calcium sulfate and calcium carbonate can be used in agriculture as a novel material to trap RKN.