DOES ELASTIN CONTRIBUTE TO THE PERSISTENCE OF CORPORA ALBICANTIA IN THE OVARY OF THE COMMON DOLPHIN (DELPHINUS DELPHIS)

The corpora albicantia (CAs) from the ovaries of 39 common dolphins ( Delphinus delphis ) caught in driving fisheries were used, and histologically and immunohistochemically examined. The area of each corpus albicans (CA) and the proportion of that area occupied by elastin were measured using NIH-image software. In all CAs, elastoid material (EM) was apparent although EM area varied in each CA. CAs increased in number with dolphin age. Smaller CAs contained a higher proportion of EM. EM was completely digested by elastase, but not by collagenase. Furthermore, EM was immunostained with anti-α-elastin antibody. These results demonstrated that EM was elastin. The present study is the first to describe the presence of elastin in cetacean CAs. The higher proportion of elastin in small-sized CAs of common dolphins is suggested as the likely cause of the persistence of CA.     

Circularized chromosome with a large palindromic structure in Streptomyces griseus mutants

Streptomyces linear chromosomes display various types of rearrangements after telomere deletion, including circularization, arm replacement, and amplification. We analyzed the new chromosomal deletion mutants Streptomyces griseus 301-22-L and 301-22-M. In these mutants, chromosomal arm replacement resulted in long terminal inverted repeats (TIRs) at both ends; different sizes were deleted again and recombined inside the TIRs, resulting in a circular chromosome with an extremely large palindrome. Short palindromic sequences were found in parent strain 2247, and these sequences might have played a role in the formation of this unique structure. Dynamic structural changes of Streptomyces linear chromosomes shown by this and previous studies revealed extraordinary strategies of members of this genus to keep a functional chromosome, even if it is linear or circular.     

Chimeric structure of omp2 of Brucella from Pacific common minke whales (Balaenoptera acutorostrata)

In the Pacific common minke whale (Balaenoptera acutorostrata ), a new variant of Brucella has been detected using the polymerase chain reaction. Detailed analysis of the porin protein genes, omp2a and omp2b from the whale Brucella showed that these two genes have some motifs in common with Atlantic marine strains in the 5'-terminal one-third region. On the other hand, the nucleotide sequences in the 3'-terminal two-thirds region of the two genes were almost identical to the respective genes of terrestrial strains. Thus, Pacific whale Brucella omp2 genes are chimeras between marine and terrestrial strains.     

Acetylation of NDPK-D Regulates Its Subcellular Localization and Cell Survival

Nucleoside diphosphate kinases (NDPK) are ubiquitous enzymes that catalyze the reversible phosphotransfer of γ-phosphates between di- and triphosphonucleosides. NDPK-D (Nm23-H4) is the only member of the NDPK family with a mitochondrial targeting sequence. Despite the high expression of NDPK-D in the developing central nervous system, its function remains to be determined. In this study, we show that NDPK-D knockdown induces apoptosis in neuroblastoma cells as well as in mouse cortex, suggesting that NDPK-D is required for neuronal survival. We identified NDPK-D as a binding partner of NAD⁺-dependent histone deacetylase, SIRT1, by yeast two-hybrid screening. NDPK-D co-localized with SIRT1, and the association of these molecules was confirmed by co-immunoprecipitation. Inhibition of SIRT1 increases the acetylation of NDPK-D. Overexpression of NDPK-D along with SIRT1, or mutation in the acetylated lysine residues in NDPK-D, increases its nuclear accumulation. Furthermore, the NDPK-D acetylation-mimic mutant increased apoptosis in N1E-115 cells. Our data demonstrate that acetylation regulates the shuttling of NDPK-D between nucleus and cytoplasm, and increased acetylation of NDPK-D causes apoptosis.     

Aldehyde Dehydrogenase 1 (ALDH1) Is a Potential Marker for Cancer Stem Cells in Embryonal Rhabdomyosarcoma

Cancer stem cells (CSCs) are defined as a small population of cancer cells with the properties of high self-renewal, differentiation, and tumor-initiating functions. Recent studies have demonstrated that aldehyde dehydrogenase 1 (ALDH1) is a marker for CSCs in adult cancers. Although CSCs have been identified in some different types of pediatric solid tumors, there have been no studies regarding the efficacy of ALDH1 as a marker for CSCs. Therefore, in order to elucidate whether ALDH1 can be used as a marker for CSCs of pediatric sarcoma, we examined the characteristics of a population of cells with a high ALDH1 activity (ALDH1^high cells) in rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children. We used the human embryonal RMS (eRMS) cell lines RD and KYM-1, and sorted the cells into two subpopulations of ALDH1^high cells and cells with a low ALDH1 activity (ALDH1^low cells). Consequently, we found that the ALDH1^high cells comprised 3.9% and 8.2% of the total cell population, respectively, and showed a higher capacity for self-renewal and tumor formation than the ALDH1^low cells. With regard to chemoresistance, the survival rate of the ALDH1^high cells was found to be higher than that of the ALDH1^low cells following treatment with chemotherapeutic agents for RMS. Furthermore, the ALDH1^high cells exhibited a higher degree of pluripotency and gene expression of Sox2, which is one of the stem cell markers. Taken together, the ALDH1^high cells possessed characteristics of CSCs, including colony formation, chemoresistance, differentiation and tumor initiation abilities. These results suggest that ALDH1 is a potentially useful marker of CSCs in eRMS.     

Molecular evidence of new variant Brucella in North Pacific common minke whales

Brucella, a causative agent of brucellosis, has been isolated recently from a variety of marine mammals. The molecular analysis of marine mammalian Brucella strains, without manifest pathology of brucellosis in the eastern North Atlantic, showed that they are distinct from terrestrial Brucella species. Previously, we reported abnormal gonads in common minke whales (Balaenoptera acutorostrata) in the western North Pacific and suggested the presence of Brucella infection in the whales in pathology and serology studies. In the present study, using polymerase chain reaction (PCR), Brucella was detected in granular testes of the whales showing caseation or calcification. The insertion of an IS711 transposable element specific for marine mammal isolates as well as a seal isolate-specific DNA fragment were also found. Molecular characterization of Brucella based on sequence analysis of the PCR products amplified from the outer membrane protein (omp) 2 gene showed that the Brucella from North Pacific common minke whales was different from terrestrial and North Atlantic marine mammal Brucella strains. The North Pacific Brucella showed the highest similarity to North Atlantic seal strains among the known Brucella strains.     

Analysis of Fusion Junctions of Circularized Chromosomes in Streptomyces griseus

A filamentous soil bacterium, Streptomyces griseus 2247, carries a 7. 8-Mb linear chromosome. We previously showed by macrorestriction analysis that mutagenic treatments easily caused deletions at both ends of its linear chromosome and changed the chromosome to a circular form. In this study, we confirmed chromosomal circularization by cloning and sequencing the junction fragments from two deletion mutants, 404-23 and N2. The junction sequences were compared with the corresponding right and left deletion end sequences in the parent strain, 2247. No homology and a 6-bp microhomology were found between the two deletion ends of the 404-23 and N2 mutants, respectively, which indicate that the chromosomal circularization was caused by illegitimate recombination without concomitant amplification. The circularized chromosomes were stably maintained in both mutants. Therefore, the chromosomal circularization might have occurred to prevent lethal deletions, which otherwise would progress into the indispensable central regions of the chromosome.