A 100%-complete sequence reveals unusually simple genomic features in the hot-spring red alga Cyanidioschyzon merolae

<p>Abstract</p> <p>Background</p> <p>All previously reported eukaryotic nuclear genome sequences have been incomplete, especially in highly repeated units and chromosomal ends. Because repetitive DNA is important for many aspects of biology, complete chromosomal structures are fundamental for understanding eukaryotic cells. Our earlier, nearly complete genome sequence of the hot-spring red alga <it>Cyanidioschyzon merolae </it>revealed several unique features, including just three ribosomal DNA copies, very few introns, and a small total number of genes. However, because the exact structures of certain functionally important repeated elements remained ambiguous, that sequence was not complete. Obviously, those ambiguities needed to be resolved before the unique features of the <it>C. merolae </it>genome could be summarized, and the ambiguities could only be resolved by completing the sequence. Therefore, we aimed to complete all previous gaps and sequence all remaining chromosomal ends, and now report the first nuclear-genome sequence for any eukaryote that is 100% complete.</p> <p>Results</p> <p>Our present complete sequence consists of 16546747 nucleotides covering 100% of the 20 linear chromosomes from telomere to telomere, representing the simple and unique chromosomal structures of the eukaryotic cell. We have unambiguously established that the <it>C. merolae </it>genome contains the smallest known histone-gene cluster, a unique telomeric repeat for all chromosomal ends, and an extremely low number of transposons.</p> <p>Conclusion</p> <p>By virtue of these attributes and others that we had discovered previously, <it>C. merolae </it>appears to have the simplest nuclear genome of the non-symbiotic eukaryotes. These unusually simple genomic features in the 100% complete genome sequence of <it>C. merolae </it>are extremely useful for further studies of eukaryotic cells.</p

ミズ カンキョウ オセン ブッシツ ノ ドウタイ ヒョウカ ケンキュウ キョテン ノ コウチク

本拠点形成では、地球規模での省資源･持続･循環社会の実現において中核となる環境科学の分野で画期的な貢献をするために、熊本大学の立地条件に配慮し、緊急性の高い水環境汚染物質の動態評価研究拠点の構築を目指す。とくに、環境悪化の原因とメカニズムが不明のまま疲弊状態にある有明･八代海の再生修復への貢献を念頭に置き、環境ホルモンなどの環境汚染物質の生物モニタリング科学創成、沿岸域における栄養塩除去などに有効な環境汚染物質のバイオ・レミディエーションの科学技術研究の展開、陸水と海水に跨る沿岸域水環境の計測･解析･評価手法の高度化と応用、微量で多様な環境汚染物質の高精度定量手法の開発と応用などの先導的研究を推進する。また、これらの研究を通じて総合的な研究能力と高度な洞察力を有する創造性豊かな人材を育成するとともに、環境産業創成に貢献する

ミズ カンキョウ オセン ブッシツ ノ ドウタイ ヒョウカ ケンキュウ キョテン ノ コウチク

本拠点形成では、地球規模での省資源･持続･循環社会の実現において中核となる環境科学の分野で画期的な貢献をするために、熊本大学の立地条件に配慮し、緊急性の高い水環境汚染物質の動態評価研究拠点の構築を目指す。とくに、環境悪化の原因とメカニズムが不明のまま疲弊状態にある有明･八代海の再生修復への貢献を念頭に置き、環境ホルモンなどの環境汚染物質の生物モニタリング科学創成、沿岸域における栄養塩除去などに有効な環境汚染物質のバイオ・レミディエーションの科学技術研究の展開、陸水と海水に跨る沿岸域水環境の計測･解析･評価手法の高度化と応用、微量で多様な環境汚染物質の高精度定量手法の開発と応用などの先導的研究を推進する。また、これらの研究を通じて総合的な研究能力と高度な洞察力を有する創造性豊かな人材を育成するとともに、環境産業創成に貢献する

ミズ カンキョウ オセン ブッシツ ノ ドウタイ ヒョウカ ケンキュウ キョテン ノ コウチク

本拠点形成では、地球規模での省資源･持続･循環社会の実現において中核となる環境科学の分野で画期的な貢献をするために、熊本大学の立地条件に配慮し、緊急性の高い水環境汚染物質の動態評価研究拠点の構築を目指す。とくに、環境悪化の原因とメカニズムが不明のまま疲弊状態にある有明･八代海の再生修復への貢献を念頭に置き、環境ホルモンなどの環境汚染物質の生物モニタリング科学創成、沿岸域における栄養塩除去などに有効な環境汚染物質のバイオ・レミディエーションの科学技術研究の展開、陸水と海水に跨る沿岸域水環境の計測･解析･評価手法の高度化と応用、微量で多様な環境汚染物質の高精度定量手法の開発と応用などの先導的研究を推進する。また、これらの研究を通じて総合的な研究能力と高度な洞察力を有する創造性豊かな人材を育成するとともに、環境産業創成に貢献する

ミズ カンキョウ オセン ブッシツ ノ ドウタイ ヒョウカ ケンキュウ キョテン ノ コウチク

本拠点形成では、地球規模での省資源･持続･循環社会の実現において中核となる環境科学の分野で画期的な貢献をするために、熊本大学の立地条件に配慮し、緊急性の高い水環境汚染物質の動態評価研究拠点の構築を目指す。とくに、環境悪化の原因とメカニズムが不明のまま疲弊状態にある有明･八代海の再生修復への貢献を念頭に置き、環境ホルモンなどの環境汚染物質の生物モニタリング科学創成、沿岸域における栄養塩除去などに有効な環境汚染物質のバイオ・レミディエーションの科学技術研究の展開、陸水と海水に跨る沿岸域水環境の計測･解析･評価手法の高度化と応用、微量で多様な環境汚染物質の高精度定量手法の開発と応用などの先導的研究を推進する。また、これらの研究を通じて総合的な研究能力と高度な洞察力を有する創造性豊かな人材を育成するとともに、環境産業創成に貢献する

Differential responses of antioxidative enzymes and lipid peroxidation to salt stress in salt-tolerant Plantago maritima and salt-sensitive Plantago media

WOS: 000249827100005PubMed ID: 18251879The changes in plant growth, relative water content (RWC), stomatal conductance, lipid peroxidation and antioxidant system in relation to the tolerance to salt stress were investigated in salt-tolerant Plantago maritima and salt-sensitive Plantago media. The 60 days old P. maritima and P. media seedlings were subjected to 0, 100 and 200 mM NaCl for 7 days. Reduction in shoot length was higher in P. media than in P. maritima after exposure to 200 mM NaCl, but 100 mM NaCl treatment did not show any effect on shoot length of P. maritima. Shoot dry weight decreased in P. media and did not change in P. maritima. Two hundred millimolar NaCl treatment had no effect on leaf RWC in P. maritima, but it was reduced in P. media. Salt stress caused reduction in stomatal conductance being more pronounced in P. media than in P. maritima. Activities of superoxide dismutase (SOD; EC 1.15.1.1), catalase (CAT; EC 1.11.1.6), glutathione reductase (GR; EC 1.6.4.2) decreased in P. media with increasing salinity. Ascorbate peroxidase (APX; EC 1.11.1.11) activity in leaves of P. media was increased and showed no change under 100 and 200 mM NaCl, respectively. However, activities of CAT, APX and GR increased under 200 mM NaCl while their activities did not change under 100 mM NaCl in P. maritima. SOD activity in leaves of P. maritima increased with increasing salinity. Concomitant with this, four SOD activity bands were identified in leaves of P. maritima, two bands only were observed in P. media. Peroxidase (POX; EC 1.11.1.7) activity increased under both salt concentrations in P. maritima, but only under 200 mM NaCl in P. media. Confirming this, five POX activity bands were identified in leaves of P. maritima, but only two bands were determined in P. media. Malondialdehyde levels in the leaves increased under salt stress in P. media but showed no change and decreased in P. maritima at 100 and 200 mM NaCl, respectively. These results suggest that the salt-tolerant P. maritima showed a better protection mechanism against oxidative damage caused by salt stress by its higher induced activities of antioxidant enzymes than the salt-sensitive P. media

Ethylene regulation of sexual reproduction in the marine red alga Pyropia yezoensis (Rhodophyta)

Plant growth regulators (PGRs) play a pivotal role in vascular plants, regulating growth, development, and stress responses; however, the role of PGRs in algae remains largely unexplored. Here, the role of ethylene, a simple plant growth regulator, was demonstrated in sexual reproduction of the marine red alga Pyropia yezoensis. Application of the ethylene precursor 1-aminocylopropane-1-carboxylic acid (ACC) promoted the formation of spermatia and zygotospores in the gametophytes as well as ethylene production, whereas the growth rate was repressed in comparison to gametophytes not treated with ACC. In addition, gametophytes treated with ACC and mature gametophytes showed enhanced tolerance to oxidative stress. Gene expression profiles revealed upregulation of genes involved in cell division and stress response in gametophytes treated with ACC and in mature gametophytes. These results indicate that ethylene plays an important role in the regulation of gamete formation and protection against stress-induced damage during the sexual reproductive stage. Considered together, these findings demonstrate that ethylene is involved in regulating the switching from a vegetative to a sexual reproductive phase in P. yezoensis

Treatment with antibiotics that interfere with peptidoglycan biosynthesis inhibits chloroplast division in the desmid Closterium.

Charophytes is a green algal group closely related to land plants. We investigated the effects of antibiotics that interfere with peptidoglycan biosynthesis on chloroplast division in the desmid Closterium peracerosum-strigosum-littorale complex. To detect cells just after division, we used colchicine, which inhibits Closterium cell elongation after division. Although normal Closterium cells had two chloroplasts before and after cell division, cells treated with ampicillin, D-cycloserine, or fosfomycin had only one chloroplast after cell division, suggesting that the cells divided without chloroplast division. The antibiotics bacitracin and vancomycin showed no obvious effect. Electron microscopic observation showed that irregular-shaped chloroplasts existed in ampicillin-treated Closterium cells. Because antibiotic treatments resulted in the appearance of long cells with irregular chloroplasts and cell death, we counted cell types in the culture. The results suggested that cells with one chloroplast appeared first and then a huge chloroplast was generated that inhibited cell division, causing elongation followed by cell death