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

3D-TEM Imaging Demonstrating Dynamic Conversion of Starch and Oil in a Cell of Chlorella sorokiniana

Recognition of the wide diversity of organisms that maintain complex haploid-diploid life cycles has generated interest in understanding the evolution and persistence of such life cycles. We empirically tested the model where complex haploid-diploid life cycles may be maintained by subtle/cryptic differences in the vital rates of isomorphic haploid-diploids, by examining the ecophysiology of haploid tetraspores and diploid carpospores of the isomorphic red alga Chondrus verrucosus. While tetraspores and carpospores of this species did not differ in size or autofluorescence, concentrations of phycobiliproteins of carpospores were greater than that of tetraspores. However, tetraspores were more photosynthetically competent than carpospores over a broader range of photosynthetic photon flux densities (PPFDs) and at PPFDs found at both the depth that C. verrucosus is found at high tide and in surface waters in which planktonic propagules might disperse. These results suggest potential differences in dispersal potential and reproductive success of haploid and diploid spores. Moreover, these cryptic differences in ecological niche partitioning of haploid and diploid spores contribute to our understanding of some of the differences between these ploidy stages that may ultimately lead to the maintenance of the complex haploid-diploid life cycle in this isomorphic red alga.

Maintenance of Complex Life Cycles Via Cryptic Differences In The Ecophysiology Of Haploid And Diploid Spores Of An Isomorphic Red Alga1.

Haptophytes are abundant phytoplankton that possess 4 membrane-bound chloroplasts. These chloroplasts originated from a red alga that was taken up by a eukaryotic host cell. No previous work has reported on the protein targeting of haptophytes, except for computational analyses. We isolated the two genes encoding chloroplast proteins AtpC1 and FtsZ from Pavlova pinguis and analyzed their molecular structure. These proteins had a bipartite sequence at the N-terminus, which consisted of an endoplasmic reticulum (ER) signal sequence followed by a chloroplast transit peptide. To demonstrate the functionality of the ER signal sequences and the chloroplast targeting sequences in vivo, we fused the predicted ER signal sequence, chloroplast transit peptide, and bipartite sequence of AtpC1 and FtsZ individually to the N-terminus of green fluorescent protein (sGFP). This was then introduced into cultured tobacco cells. Microscopic observation revealed that the predicted ER signal sequences of AtpC1 and FtsZ had the ability to localize to the ER, and the following amino acids worked as a chloroplast transit peptide in the tobacco cells. We concluded that the AtpC1 and FtsZ of P. pinguis have a bipartite sequence at the N-terminus and a molecular structure in common with other independently established secondarily endosymbiotic algae.

Isolation of chloroplast FtsZ and AtpC, and analysis of protein targeting into the complex chloroplast of the haptophyte Pavlova pinguis

Novel Dynamics of FtsZ Ring Before Plastid Abscission

Cytokinesis is a pivotal event in cell division in all living organisms. In mammals, cytokinesis progresses via constriction of the contractile ring, a bundle of actin filaments and myosin that is located on the equatorial plane. The eukaryotic elongation factor 1α (eEF-1α) is associated with the contractile ring in sea urchin eggs. Although eEF-1α is a ubiquitous protein translation factor and is highly conserved in eukaryotes, archaea, and prokaryotes, the archaebacterial EF-1α and the prokaryotic EF-1α ortholog EF-Tu do not function in cytokinesis, suggesting that the association between the contractile ring and EF-1α appeared at about the same time as the establishment of eukaryotic cells. However, the role of EF-1α in cytokinesis in primitive cells is unclear. In this study, we show that the primitive alga Cyanidioschyzon merolae elongation factor-lα (CmEF-1α) is localized in the contractile division plane, but not in the actomyosin contractile ring. The genome of C. merolae contains 2 unexpressed actin genes and lacks a myosin gene. Immunoblotting analyses revealed that the protein level of CmEF-1α remained constant during the G1 to M phase, and then peaked during cytokinesis. Immunofluorescent microscopy revealed 2 patterns of localization of CmEF-1α during the cell cycle: it was dispersed throughout the cytoplasm from G1 to early M phase, and then localized to the contractile region during cytokinesis. From the results of current study on cytokinesis in the primitive red algae C. merolae, our findings led us to hypothesize that when first established in the lower eukaryotes, cytokinesis fundamentally relied on eEF-1α, and the actomyosin system was acquired later during evolution.

/pdf/involvement-of-elongation-factor-1a-in-cytokinesis-without-371ueazol0.pdf

Shigeyuki Kawano

Papers

3D-TEM Imaging Demonstrating Dynamic Conversion of Starch and Oil in a Cell of Chlorella sorokiniana

Maintenance of Complex Life Cycles Via Cryptic Differences In The Ecophysiology Of Haploid And Diploid Spores Of An Isomorphic Red Alga1.

Isolation of chloroplast FtsZ and AtpC, and analysis of protein targeting into the complex chloroplast of the haptophyte Pavlova pinguis

Novel Dynamics of FtsZ Ring Before Plastid Abscission

Involvement of Elongation Factor-1α in Cytokinesis without Actomyosin Contractile Ring in the Primitive Red Alga Cyanidioschyzon merolae