Evolution of Protein Molecules

Mitochondria are dynamic organelles that constantly fuse and divide. These processes (collectively termed mitochondrial dynamics) are important for mitochondrial inheritance and for the maintenance of mitochondrial functions. The core components of the evolutionarily conserved fusion and fission machineries have now been identified, and mechanistic studies have revealed the first secrets of the complex processes that govern fusion and fission of a double membrane-bound organelle. Mitochondrial dynamics was recently recognized as an important constituent of cellular quality control. Defects have detrimental consequences on bioenergetic supply and contribute to the pathogenesis of neurodegenerative diseases. These findings open exciting new directions to explore mitochondrial biology.

http://fulltext.calis.edu.cn/nature/nrm/11/12/nrm3013.pdf

Mitochondrial fusion and fission in cell life and death

INTRODUCTION. Internal Organization of the Plant Body. Summary of Types of Cells and Tissues. General References. DEVELOPMENT OF THE SEED PLANT. The Embryo. From embryo to the Adult Plant. Apical Meristems and Their Derivatives. Differentiation, Specialization, and Morphogenesis. References. THE CELL. Cytoplasm. Nucleus. Plastids. Mitochondria. Microbodies. Vacuoles. Paramural Bodies. Ribosomes. Dictyosomes. Endoplasmic Reticulum. Lipid Globules. Microtubules. Ergastic Substances. References. CELL WALL. Macromolecular Components and Their Organization in the Wall. Cell Wall Layers. Intercellular Spaces. Pits, Primary Pit--Fields, and Plasmodesmata. Origin of Cell Wall During Cell Division. Growth of Cell Wall. References. PARENCHYMA AND COLLENCHYMA. Parenchyma. Collenchyma. References. SCLERENCHYMA. Sclereids. Fibers. Development of Sclereids and Fibers. References. EPIDERMIS. Composition. Developmental Aspects. Cell Wall. Stomata. Trichomes. References. XYLEM: GENERAL STRUCTURE AND CELL TYPES. Gross Structure of Secondary Xylem. Cell Types in the Secondary Xylem. Primary Xylem. Differentiation of Tracheary Elements. References. XYLEM: VARIATION IN WOOD STRUCTURE. Conifer Wood. Dicotyledon Wood. Some Factors in Development of Secondary Xylem. Identification of Wood. References. VASCULAR CAMBIUM. Organization of Cambium. Developmental Changes in the Initial Layer. Patterns and Causal Relations in Cambial Activity. References. PHLOEM. Cell Types. Primary Phloem. Secondary Phloem. References. PERIDERM. Structure of Periderm and Related Tissues. Development of Periderm. Outer Aspect of Bark in Relation to Structure. Lenticels. References. SECRETORY STRUCTURES. External Secretory Structures. Internal Secretory Structures. References. THE ROOT: PRIMARY STATE OF GROWTH. Types of Roots. Primary Structure. Development. References. THE ROOT: SECONDARY STATE OF GROWTH AND ADVENTITIOUS ROOTS. Common Types of Secondary Growth. Variations in Secondary Growths. Physiologic Aspects of Secondary Growth in Roots. Adventitious Roots. References. THE STEM: PRIMARY STATE OF GROWTH. External Morphology. Primary Structure. Development. References. THE STEM: SECONDARY GROWTH AND STRUCTURAL TYPES. Secondary Growth. Types of Stems. References. THE LEAF: BASIC STRUCTURE AND DEVELOPMENT. Morphology. Histology of Angiosperm Leaf. Development. Abscission. References. THE LEAF: VARIATIONS IN STRUCTURE. Leaf Structure and Environment. Dicotyledon Leaves. Monocotyledon Leaves. Gymnosperm Leaves. References. THE FLOWER: STRUCTURE AND DEVELOPMENT. Concept. Structure. Development. References. THE FLOWER: REPRODUCTIVE CYCLE. Microsporogenesis. Pollen. Male Gametophyte. Megasporogenesis. Female Gametophyte. Fertilization. References. THE FRUIT. Concept and Classification. The Fruit Wall. Fruit Types. Fruit Growths. Fruit Abscission. References. THE SEED. Concept and Morphology. Seed Development. Seed Coat. Nutrient Storage Tissues. References. EMBRYO AND SEEDLING. Mature Embryo. Development of Embryo. Classification of Embryos. Seedling. References. Glossary. Index.

Anatomy of Seed Plants

The structure

Small, compact genomes of ultrasmall unicellular algae provide information on the basic and essential genes that support the lives of photosynthetic eukaryotes, including higher plants. Here we report the 16,520,305-base-pair sequence of the 20 chromosomes of the unicellular red alga Cyanidioschyzon merolae 10D as the first complete algal genome. We identified 5,331 genes in total, of which at least 86.3% were expressed. Unique characteristics of this genomic structure include: a lack of introns in all but 26 genes; only three copies of ribosomal DNA units that maintain the nucleolus; and two dynamin genes that are involved only in the division of mitochondria and plastids. The conserved mosaic origin of Calvin cycle enzymes in this red alga and in green plants supports the hypothesis of the existence of single primary plastid endosymbiosis. The lack of a myosin gene, in addition to the unexpressed actin gene, suggests a simpler system of cytokinesis. These results indicate that the C. merolae genome provides a model system with a simple gene composition for studying the origin, evolution and fundamental mechanisms of eukaryotic cells.

/pdf/genome-sequence-of-the-ultrasmall-unicellular-red-alga-b1ng9438pg.pdf

Genome sequence of the ultrasmall unicellular red alga Cyanidioschyzon merolae 10D

1 Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113–8657, Japan 2 Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630–0101, Japan 3 Tohoku Agricultural Research Center, National Agriculture and Food Research Organization, Morioka, Iwate 020–0198, Japan 4 Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277–8562, Japan

Algal Genes Encoding Enzymes for Photosynthesis and Hydrocarbon Biosynthesis as Candidates for Genetic Engineering

The active, selective digestion of mitochondrial DNA (mtDNA) from 1 parent in the zygote is a possible molecular mechanism for the uniparental inheritance of mitochondria, but direct evidence has been observed in few species. In this study, we observed the behavior of mitochondria and mtDNA during mating of the myxamoeba of the true slime mold Didymium iridis. To show the selective digestion of mtDNA in the zygote, 2 myxamoebal strains of D. iridis were crossed, and the changes of mitochondria and mtDNA were observed over time by phase-contrast observation using alkaline fixation method and DAPI staining. Each myxamoeba of D. iridis contained about 30 mitochondria, and the zygote had about 60. Each mitochondrion contains rod-shaped mtDNA. About 4.5 h after mating, the fluorescence of mtDNA in about 30 mitochondria decreased simultaneously to give small spots, and then disappeared completely by 5 h after mating. In contrast, the mtDNA in the other 30 mitochondria and all of the mitochondrial sheaths remained unchanged. This is the fourth microscopic report that shows selective mtDNA disappearance. The rapid, selective disappearance of mtDNA observed in D. iridis is likely the result of selective digestion of mtDNA from 1 parent, as in other known cases of mtDNA disappearance.

Disappearance of mtDNA During Mating of the True Slime Mold Didymium iridis

SUMMARY

A giant mitochondrion that branches and connects as a single mitochondrion in a cell has been observed during specific phases of the cell cycle of unicellular green algae, but has not been observed in multicellular algae. The genus Ulva is a green macroalga in which the haploid and diploid phases are isomorphic and its gametes develop parthenogenetically. The existence or absence of the giant mitochondrion, and its behavior in Ulva partita, were investigated using a parthenogenesis system. To observe the parthenogenesis of gametes and the dynamics of mitochondria by fluorescence microscopy, we developed an experimental system for culturing and observing U. partita on cover slips: gametes were suspended in 6-well plates filled with artificial seawater, and cover slips were placed on the well bottoms. The gametes settled on the cover slips as spherical cells (1-cell S phase). These cells grew into larger cells, losing their eyespot (1-cell L phase), and developed into multicellular thalli. Gene introduction using the polyethylene glycol (PEG) method is available with transformation efficiencies of 9.0–15.1%. Transformation was performed using a plasmid encoding green fluorescent protein (GFP) fused to the mitochondrial targeting sequence, and mitochondria were labeled by GFP fluorescence. This revealed a string-shaped giant mitochondrion in a cell of the 1-cell S phase. In the 1-cell L phase, a reticular mitochondrion was observed. After the initiation of cell division, the reticular mitochondrion was fragmented, and small oval mitochondria were observed in the 5-cell phase.

Morphological changes of giant mitochondria in the unicellular to multicellular phase during parthenogenesis of Ulva partita (Ulvophyceae) revealed by expression of mitochondrial targeting GFP and PEG transformation

/pdf/the-parachlorella-genome-and-transcriptome-endorse-active-4q11827qkn.pdf

The Parachlorella Genome and Transcriptome Endorse Active RWP-RK, Meiosis and Flagellar Genes in Trebouxiophycean Algae

The shoot apical meristem of a day-neutral desert ephemeral Pectis papposa was examined by SEM. Under axenic conditions with continuous light, seedlings grew very fast. Only 6 days after sowing, the shoot apical meristem formed the dome and produced three bracteal primordia after developing three sets of foliage leaves. This meant the flower initiation occurred at 6th day. It seems to be the fastest flowering plant ever investigated. The observation here brings the possibility to investigate whole the vegetative phase to elucidate the very beginning of the flower initiation.

Shigeyuki Kawano

Papers

Algal Genes Encoding Enzymes for Photosynthesis and Hydrocarbon Biosynthesis as Candidates for Genetic Engineering

Disappearance of mtDNA During Mating of the True Slime Mold Didymium iridis

Morphological changes of giant mitochondria in the unicellular to multicellular phase during parthenogenesis of Ulva partita (Ulvophyceae) revealed by expression of mitochondrial targeting GFP and PEG transformation

The Parachlorella Genome and Transcriptome Endorse Active RWP-RK, Meiosis and Flagellar Genes in Trebouxiophycean Algae

Rapid Flower Initiation of a Desert Ephemeral Pectis papposa Gray