ATP-dependent chromatin remodelers (ADCRs) convert local chromatin structure into both transcriptional active and repressive state. Recent studies have revealed that ADCRs play diverse regulatory roles in chromosomal events such as DNA repair and recombination. Here we have newly identified a fission yeast gene encoding a Swi2/Snf2 family ADCR. The amino acid sequence of this gene, snf21⁺, implies that Snf21 is a fission yeast orthologue of the budding yeast Sth1, the catalytic core of the RSC chromatin remodeling complex. The snf21⁺ gene product is a nuclear protein essential to cell viability: the null mutant cells stop growing after several rounds of cell divisions. A temperature sensitive allele of snf21⁺, snf21-36 exhibits at non-permissive temperature (34°C) a cell cycle arrest at G2-M phase and defects in chromosome segregation, thereby causing cell elongation, lack of cell growth, and death of some cell population. snf21-36 shows thiabendazole (TBZ) sensitivity even at permissive temperature (25°C). The TBZ sensitivity becomes severer as snf21-36 is combined with the deletion of a centromere-localized Mad2 spindle checkpoint protein. The cell cycle arrest phenotype at 34°C cannot be rescued by the mad2⁺ deletion, although it is substantially alleviated at 30°C in mad2Δ. These data suggest that Snf21 plays an essential role in mitosis possibly functioning in centromeric chromatin.

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In the fission yeast Schizosaccharomyces pombe, three P-type ATPases, namely Cta4p, Pmr1p, and Pmc1p, have been shown to be essential for Ca²⁺ homeostasis and are required for specific cellular functions as well. Here, we show that the simultaneous deletion of pmc1⁺ and SPAC29A4.19c, which encodes a putative P₅-type ATPase, causes a hypersensitive growth to either high concentrations of Ca²⁺ in a medium, or the antiarrhythmic drug amiodarone, which has been known to cause a disruption of Ca²⁺ homeostasis. On the other hand, simultaneous deletion of pmr1⁺ and SPAC29A4.19c causes a hypersensitive growth to Mn²⁺ depletion in a medium. The green fluorescent protein-tagged SPAC29A4.19c protein reveals a typical localization pattern of the Golgi proteins, but the SPAC29A4.19c protein is not exchangeable in function with Pmr1p, which is required for Ca²⁺/Mn²⁺ homeostasis in secretory pathways. These results suggest that the putative P₅-type ATPase encoded by SPAC29A4.19c is essential for Ca²⁺ and Mn²⁺ homeostasis in the absence of P₂-type ATPases, Pmc1p or Pmr1p, respectively. According to the precedent nomenclature of calcium/cation transporting ATPase in fission yeast, SPAC29A4.19 was named cta5⁺ in this study.

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The Sea Island cotton (Gossypium barbadense L.) has been highly valued in verticillium wilt resistance and many fiber qualities including fiber length, strength and fineness. To identify whether it had some special genes in fiber development in comparison with the Upland cotton (G. hirsutum L.), an actin-depolymerizing factor (ADF) gene was cloned and characterized in this research. A 420 bp open reading frame of the cloned gene, named GbADF1, encoded a protein of 139 amino acids, including 39.57% nonpolar amino acids, 17.27% acidic amino acids, 15.83% basic amino acids and 31.92% hydrophobic amino acids. Its molecular weight was about 15 kDa, and pI 5.04. GbADF1 contained two conserved domains, 6-Ser and the PIP2/actin binding site. Its amino acid sequence was similar to the ADF/cofilin family of other plants. Compared with cDNA sequence, the GbADF1 gene contained one intron near the 3’ end in genomic sequence. Semi-quantitative RT-PCR result showed that GbADF1 was a constitutive expression gene in cotton, and higher expression level was detected in fibers than in trophic tissues. The GbADF1 was successfully expressed as a fusion protein in Escherichia coli BL21 (DE3). The molecular weight was firstly calculated by SDS-PAGE. Western blotting analysis confirmed the existence of a protein corresponding to GbADF1. The structure of GbADF1 was different from that of other ADF genes in higher plant, although the coding sequences of all cloned ADFs were highly conserved.

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We have constructed a BAC library for common buckwheat Fagopyrum esculentum Moench. The library includes 142,005 clones with an average insert size of ~76 kb, equivalent to approximately a 7~8-fold coverage of the genome. Polymerase chain reaction based screening of the library with AGAMOUS and FLORICAULA/LEAFY primers, has identified 7 and 9 BACs, respectively, which are consistent with the genome coverage. This library represents the first large insert genomic library for F. esculentum and it can be served as a genetic resource facilitating agricultural, pharmacological, physiological, and evolutionary studies of the species. To demonstrate the utilization of the library for characterizing agriculturally valuable traits, we developed a sequence tagged site marker tightly linked to the dwarf E locus as well as to the self-incompatibility complex locus and screened the library to initiate positional cloning of the causative genes.

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The level and pattern of nucleotide variation in the SUPERWOMAN1(SPW1) locus of the wild rice Oriza rufipogon and its related species were analyzed. SPW1 is orthologous to APETELA3(AP3) in Arabidopsis thaliana. The estimated level of nucleotide variation for the entire region (π = 0.0046) was intermediate among those for other genes of O. rufipogon, although the estimates varied considerably among the SPW1 domains. Complicated haplotype structure was detected, resulting in a high proportion of significant linkage disequilibrium. Deviation from the neutrality was not detected. However, purifying selection was suggested by lack of replacement variation in the MADS-box and I-domain regions, which function as DNA-binding domain. On the other hand, an excess of drastic amino acid changes was detected in the C-domain, as in the AP3 region of A. thaliana. Taken together, these results imply that different types of natural selection are acting among different domains of a single protein. In the phylogenetic tree, O. sativa strains were included in the same cluster of O. rufipogon, supporting the hypothesis that O. rufipogon is the wild ancestor of O. sativa.

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A cytogenetical study was carried out on 34 specimens of the European bitterling Rhodeus amarus (Teleostei: Cyprinidae, Acheilognathinae) from four rivers of the Venice district (NE Italy). This allochthonous fish species was accidentally introduced in the North-East of Italy about 20 years ago and is now rapidly spreading all over the rivers of the Northern part of the country. All the studied specimens are characterised by the same karyotype (2n = 48: 8M + 20SM + 20ST), i.e., the typical one of the native populations of the species. However, a polymorphism in the number of NOR bearing chromosomes has been found. In fact, in addition to the main species-specific NORs, on the short arms of chromosome pair 7, two to five additional 18S rDNA sites have been revealed by FISH in different specimens. Sequential staining with silver nitrate, chromomycin A₃ and DAPI revealed that most of the additional sites are inactive and CMA₃-positive.
Data herein reported confirm that in spite of an overall morphological karyological conservativeness, significant differences for the finer cytogenetic features can be found within the Acheilognathinae with the 2n = 48 and NF = 76 karyotype.

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We verified whether telomere length shortens with age in the loggerhead sea turtle (Caretta caretta) by measuring telomere lengths (relative telomere to single copy gene [T/S] ratios) in whole blood and epidermis from 20 captive individuals with a real-time PCR method. There was no significant correlation between age and relative T/S ratios in blood. Although the correlation between age and relative T/S ratios in epidermis was not significant, older turtles had smaller relative T/S ratios in epidermis. It was thus demonstrated that telomere length in epidermis could be a useful age estimator for sea turtles. Relative age information obtained with this simple, rapid, non-invasive technique may help to advance our understanding of the ecology of endangered sea turtles. This is the first publication on age-related changes in telomere length among chelonians.

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Replication checkpoint protein Rad17 senses DNA lesions during DNA replication and halts progression of replication fork. The cells derived from Bloom syndrome individuals show some defects in DNA replication. In order to investigate the functional relationship between the replication checkpoint protein Rad17 and BLM, which is the product of the causative gene of Bloom syndrome, we generated BLM/RAD17 double knockout (blm/rad17) cells using chicken DT40 cells. The blm/rad17 cells showed exaggerated growth defects as determined by analysis of their growth curves and plating efficiency compared to those of either of the single gene mutants. These defects seem to be due to an increase in DNA lesions that cause spontaneous cell death, suggesting that Rad17 and BLM execute different functions in the progression of replication forks. We also demonstrate that targeting integration was dramatically compromised by a lack of Rad17. In addition, the elevated frequency of sister chromatid exchange (SCE) due to homologous recombination in BLM knockout (blm) cells was greatly reduced by disruption of the RAD17 gene. Thus, in addition to its role in the replication checkpoint, Rad17 appears to play a role in homologous recombination.

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