Effects of the Timing of the Life-Cycle on the Vegetative Growth of Some Dune Annuals

1976 ◽  
Vol 64 (1) ◽  
pp. 213 ◽  
Author(s):  
M. A. Pemadasa ◽  
P. H. Lovell
Keyword(s):  
Life Cycle ◽  
Vegetative Growth

Molecular cloning of casein kinase II alpha subunit from Dictyostelium discoideum and its expression in the life cycle

1992 ◽  
Vol 12 (12) ◽  
pp. 5711-5723
Author(s):  
U Kikkawa ◽  
S K Mann ◽  
R A Firtel ◽  
T Hunter
Keyword(s):  
Life Cycle ◽  
Dictyostelium Discoideum ◽  
Cdna Clone ◽  
Blot Analysis ◽  
Vegetative Growth ◽  
Casein Kinase Ii ◽  
Casein Kinase ◽  
Developmental Expression ◽  
Alpha Subunit ◽  
Alpha Gene

A Dictyostelium discoideum cDNA encoding an alpha-type subunit of casein kinase II was isolated, and its cDNA was used to study developmental expression of casein kinase II during the Dictyostelium life cycle. The 1.3-kb cDNA insert contained an open reading frame of 337 amino acids (M(r) 39,900). The deduced amino acid sequence has high homology with those of casein kinase II alpha subunits from other species. Genomic Southern blot analysis suggested that there is a single gene encoding casein kinase II alpha subunit in D. discoideum. Northern (RNA) blot analysis showed that the casein kinase II alpha-subunit gene is expressed constitutively as a 1.9-kb mRNA throughout vegetative growth and multicellular development. Casein kinase purified from normal vegetative cells contained a major protein band of approximately 36 kDa, which was recognized by antisera raised against rat testis casein kinase II. Comparison of the in vitro transcription/translation product of the alpha-subunit cDNA clone and the purified 36-kDa protein by partial proteolysis indicated that the isolated cDNA clone encodes the Dictyostelium casein kinase II alpha subunit. No protein corresponding to a beta subunit was detected in purified casein kinase. Immunoblot analysis using anti-rat casein kinase II sera showed that the alpha subunit of casein kinase II is expressed constitutively like its mRNA during the life cycle of D. discoideum. Casein kinase II activity measured by using a specific peptide substrate paralleled the level of alpha subunit detected by immunoblotting during the life cycle, with a maximum variation of approximately 2-fold. We were unable to obtain disruptants of the casein kinase II alpha gene, suggesting that there is a single casein kinase II alpha gene, which is essential for vegetative growth of D. discoideum.

The Leeuwenhoek Lecture, 1987 - Towards an understanding of gene switching in Streptomyces , the basis of sporulation and antibiotic production

1988 ◽  
Vol 235 (1279) ◽  
pp. 121-138 ◽  
Keyword(s):  
Life Cycle ◽  
Secondary Metabolites ◽  
Vegetative Growth ◽  
Antibiotic Production ◽  
Morphological Differentiation ◽  
Aerial Mycelium ◽  
Secondary Phase ◽  
Antibiotic Biosynthesis ◽  
Regulatory Cascade ◽  
Pharmacologically Active

Streptomycetes are soil bacteria that differ from the genetically well-known Escherichia coli in two striking characteristics. (1) Instead of consisting of an alternation of growth and fission of morphologically simple, undifferentiated rods, the streptomycete life cycle involves the formation of a system of elongated, branching hyphae which, after a period of vegetative growth, respond to specific signals by producing specialized spore-bearing structures. (2) The streptomycetes produce an unrivalled range of chemically diverse ‘secondary metabolites’, which we recognize as antibiotics, herbicides and pharmacologically active molecules, and which presumably play an important role in the streptomycete life cycle in nature. This ‘physiological’ differentiation is often tem­porally associated with the morphological differentiation of sporulation and there are common elements in the regulation of the two sets of processes. In the model system provided by Streptomyces coelicolor A3(2), the isolation of several whole clusters of linked antibiotic biosynthetic pathway genes, and some key regulatory genes involved in sporulation, has made it possible to study the basis for the switching on and off of particular sets of genes during morphological and ‘physiological’ differen­tiation. Genetic analysis clearly reveals a regulatory cascade operating at several levels in a ‘physiological’ branch of the differentiation control system. At the lowest level, within individual clusters of antibiotic biosynthesis genes are genes with a role as activators of the structural genes for the pathway enzymes, and also resistance genes. It is attractive to speculate that the latter play a dual role: protecting the organism from self-destruction by its own potentially lethal product, and forming an essential component of a regulatory circuit that activates the biosyn­thetic genes, thus ensuring that resistance is established before any antibiotic is made. A next higher level of regulation is revealed by the isolation of mutations in a gene ( afsB ) required for expression (probably at the level of transcription) of all five known secondary metabolic pathways in the organism. At a higher level still, the bldA gene, whose product seems to be a tRNA essential to translate the rare (in high [G + C] Streptomyces DNA) TTA leucine codon, controls or influences the whole gamut of morphological and ‘physiological’ differentiation, because bldA mutants fail to produce either secondary metabolites or aerial mycelium and spores, while growing normally in the vegetative phase. Thus a decision to switch from vegetative growth to the secondary phase of colonial development may be taken at the level of translation. In the ‘morphological’ branch of the proposed regulatory cascade, a key gene is whiG whose product, essential for the earliest known step in the metamorphosis of aerial hyphae into spore chains, appears to be an RNA polymerase sigma factor which is not needed for transcription of vegetative genes, but seems to control, at the level of transcription, the decision to sporulate.

scholarly journals Polydiglycosylphosphate Transferase PdtA (SCO2578) of Streptomyces coelicolor A3(2) Is Crucial for Proper Sporulation and Apical Tip Extension under Stress Conditions

2016 ◽  
Vol 82 (18) ◽  
pp. 5661-5672 ◽  
Author(s):  
Steffen Sigle ◽  
Nadja Steblau ◽  
Wolfgang Wohlleben ◽  
Günther Muth
Keyword(s):  
Cell Wall ◽  
Life Cycle ◽  
Vegetative Growth ◽  
Cell Envelope ◽  
Streptomyces Coelicolor ◽  
Morphological Differentiation ◽  
Spore Wall ◽  
Stress Conditions ◽  
Content Type ◽  
Tip Extension

ABSTRACTAlthough anionic glycopolymers are crucial components of the Gram-positive cell envelope, the relevance of anionic glycopolymers for vegetative growth and morphological differentiation ofStreptomyces coelicolorA3(2) is unknown. Here, we show that the LytR-CpsA-Psr (LCP) protein PdtA (SCO2578), a TagV-like glycopolymer transferase, has a dual function in theS. coelicolorA3(2) life cycle. Despite the presence of 10 additional LCP homologs, PdtA is crucial for proper sporulation. The integrity of the spore envelope was severely affected in apdtAdeletion mutant, resulting in 34% nonviable spores.pdtAdeletion caused a significant reduction in the polydiglycosylphosphate content of the spore envelope. Beyond that, apical tip extension and normal branching of vegetative mycelium were severely impaired on high-salt medium. This growth defect coincided with the mislocalization of peptidoglycan synthesis. Thus, PdtA itself or the polydiglycosylphosphate attached to the peptidoglycan by the glycopolymer transferase PdtA also has a crucial function in apical tip extension of vegetative hyphae under stress conditions.IMPORTANCEAnionic glycopolymers are underappreciated components of the Gram-positive cell envelope. They provide rigidity to the cell wall and position extracellular enzymes involved in peptidoglycan remodeling. AlthoughStreptomyces coelicolorA3(2), the model organism for bacterial antibiotic production, is known to produce two distinct cell wall-linked glycopolymers, teichulosonic acid and polydiglycosylphosphate, the role of these glycopolymers in theS. coelicolorA3(2) life cycle has not been addressed so far. This study reveals a crucial function of the anionic glycopolymer polydiglycosylphosphate for the growth and morphological differentiation ofS. coelicolorA3(2). Polydiglycosylphosphate is attached to the spore wall by the LytR-CpsA-Psr protein PdtA (SCO2578), a component of theStreptomycesspore wall-synthesizing complex (SSSC), to ensure the integrity of the spore envelope. Surprisingly, PdtA also has a crucial role in vegetative growth under stress conditions and is required for proper peptidoglycan incorporation during apical tip extension.

scholarly journals Molecular cloning of casein kinase II alpha subunit from Dictyostelium discoideum and its expression in the life cycle.

1992 ◽  
Vol 12 (12) ◽  
pp. 5711-5723 ◽  
Author(s):  
U Kikkawa ◽  
S K Mann ◽  
R A Firtel ◽  
T Hunter
Keyword(s):  
Life Cycle ◽  
Dictyostelium Discoideum ◽  
Cdna Clone ◽  
Blot Analysis ◽  
Vegetative Growth ◽  
Casein Kinase Ii ◽  
Casein Kinase ◽  
Developmental Expression ◽  
Alpha Subunit ◽  
Alpha Gene

A Dictyostelium discoideum cDNA encoding an alpha-type subunit of casein kinase II was isolated, and its cDNA was used to study developmental expression of casein kinase II during the Dictyostelium life cycle. The 1.3-kb cDNA insert contained an open reading frame of 337 amino acids (M(r) 39,900). The deduced amino acid sequence has high homology with those of casein kinase II alpha subunits from other species. Genomic Southern blot analysis suggested that there is a single gene encoding casein kinase II alpha subunit in D. discoideum. Northern (RNA) blot analysis showed that the casein kinase II alpha-subunit gene is expressed constitutively as a 1.9-kb mRNA throughout vegetative growth and multicellular development. Casein kinase purified from normal vegetative cells contained a major protein band of approximately 36 kDa, which was recognized by antisera raised against rat testis casein kinase II. Comparison of the in vitro transcription/translation product of the alpha-subunit cDNA clone and the purified 36-kDa protein by partial proteolysis indicated that the isolated cDNA clone encodes the Dictyostelium casein kinase II alpha subunit. No protein corresponding to a beta subunit was detected in purified casein kinase. Immunoblot analysis using anti-rat casein kinase II sera showed that the alpha subunit of casein kinase II is expressed constitutively like its mRNA during the life cycle of D. discoideum. Casein kinase II activity measured by using a specific peptide substrate paralleled the level of alpha subunit detected by immunoblotting during the life cycle, with a maximum variation of approximately 2-fold. We were unable to obtain disruptants of the casein kinase II alpha gene, suggesting that there is a single casein kinase II alpha gene, which is essential for vegetative growth of D. discoideum.

Phenological development in two-row spring barley when grown in a long-day (Alberta, Canada) and a short-day (Western Australia, Australia) environment

2001 ◽  
Vol 81 (4) ◽  
pp. 621-629 ◽  
Author(s):  
B. H. Paynter ◽  
P. E. Juskiw ◽  
J. H. Helm
Keyword(s):  
Life Cycle ◽  
Western Australia ◽  
Vegetative Growth ◽  
Spring Barley ◽  
Stem Growth ◽  
Vegetative Phase ◽  
Late Flowering ◽  
Short Day ◽  
Long Day ◽  
Double Ridge

Phenological development in eight cultivars of two-row, spring barley (Hordeum vulgare L.) was examined when sown at two dates of seeding in two diverse environments. These environments were a short-day environment at Northam, Western Australia, Australia, in 1997 and a long-day environment at Lacombe, Alberta, Canada, in 1998. The Australian and Canadian barley cultivars used had different combinations of basic vegetative phase and daylength sensitivity. Barley grown at Lacombe reached each stage of phenological development in less time than at Northam. Most noticeable was a shorter duration of the period between seedling emergence to double ridge and between double ridge and awn emergence. At Northam, nearly 20% of the barley’s life cycle was spent on vegetative growth, just over 40% on ear/stem growth and close to 40% on grain filling. At Lacombe, barley spent nearly 55% of its life cycle filling grain and only 10% on vegetative growth and 35% on ear/stem growth. Later seeding accelerated all stages of development at Northam but only those stages until awn emergence at Lacombe. Late-sown barley at Lacombe took longer to reach physiological maturity. The relative contribution of each phase of crop growth was unaffected by date of seeding. Based on the time to awn emergence, Franklin was a very late flowering cultivar in both environments; Fitzgerald, Gairdner and Manley were late flowering; AC Oxbow and Harrington were mid-flowering; and Stirling was early flowering. Skiff was late flowering at North am but early flowering at Lacombe. Key words: barley (spring), phenological development, daylength sensitivity, basic vegetative phase

scholarly journals Origin Usage during Euplotes Ribosomal DNA Amplification

2003 ◽  
Vol 2 (1) ◽  
pp. 115-122 ◽  
Author(s):  
Ming Tan ◽  
Carolyn L. Jahn ◽  
Carolyn M. Price
Keyword(s):  
Life Cycle ◽  
Ribosomal Dna ◽  
Vegetative Growth ◽  
Promoter Region ◽  
Replication Fork ◽  
Dna Amplification ◽  
Replication Initiation ◽  
Two Dimensional ◽  
Sexual Stage ◽  
Replication Intermediates

ABSTRACT The macronuclear genome of the ciliate Euplotes is comprised of millions of small linear DNA molecules that have telomeres on each end. These molecules are generated during the sexual stage of the life cycle, when the new macronucleus is formed by a series of DNA processing events and multiple rounds of DNA amplification. We have used two-dimensional gels to compare the location of the replication origins used during vegetative growth and the two periods during macronuclear development when DNA amplification takes place. When we examined the pattern of ribosomal DNA (rDNA) replication intermediates, we observed almost identical Y arcs regardless of when in the Euplotes life cycle the DNA was isolated. No bubble or bubble-to-Y arcs could be detected. This indicates that replication of the macronuclear rDNA initiates at or near the telomere even when these molecules are being differentially amplified. Since replication rarely initiated from both ends of the rDNA, we examined the direction of replication fork movement to determine which end of the rDNA served as the origin. Fork movement gels indicated that replication initiated at the 5′ end. As transcription also starts near the telomere at the 5′ end, our findings suggest that the telomere and the promoter region cooperate to recruit Euplotes replication initiation complexes.

scholarly journals Cell Wall Hydrolases Affect Germination, Vegetative Growth, and Sporulation in Streptomyces coelicolor

2009 ◽  
Vol 191 (21) ◽  
pp. 6501-6512 ◽  
Author(s):  
Henry J. Haiser ◽  
Mary R. Yousef ◽  
Marie A. Elliot
Keyword(s):  
Cell Wall ◽  
Life Cycle ◽  
Vegetative Growth ◽  
Streptomyces Coelicolor ◽  
Hydrolytic Enzymes ◽  
In Silico Analysis ◽  
Cell Types ◽  
Complex Life Cycle ◽  
Cell Wall Remodeling ◽  
Cell Growth And Differentiation

ABSTRACT Peptidoglycan is a major cell wall constituent of gram-positive bacteria. It is a dynamic macromolecule that is actively remodeled to enable cell growth and differentiation through a tightly choreographed interplay of hydrolytic and biosynthetic enzyme activities. The filamentous bacterium Streptomyces coelicolor has a complex life cycle that likely requires considerable cell wall remodeling to enable both extension of vegetative hyphae and formation of differentiated cell types. In silico analysis of the S. coelicolor genome enabled identification of 56 candidate cell wall hydrolase genes. We found that seven of these genes shared a highly conserved 5′ untranslated region and were expressed during both vegetative growth and sporulation; four of these genes were selected for more extensive biochemical and biological characterization. The proteins encoded by these genes, termed RpfA, SwlA, SwlB, and SwlC, were confirmed to be hydrolytic enzymes, as they could efficiently cleave S. coelicolor cell walls. Phenotypic analyses revealed that these enzymes are important throughout development; deletion of each hydrolase gene resulted in a mutant strain that was heat sensitive, defective in spore formation, and either altered in vegetative growth or delayed in spore germination. Our results indicate that these enzymes play key roles at multiple stages in the growth and development of S. coelicolor, highlighting both the lack of redundancy in hydrolase activity and the importance of cell wall remodeling in the S. coelicolor life cycle.

Timing of the appearance of ubiquitinated histones in developing new macronuclei of Tetrahymena thermophila

1991 ◽  
Vol 69 (1) ◽  
pp. 66-71 ◽  
Author(s):  
James R. Davie ◽  
Rueyling Lin ◽  
C. David Allis
Keyword(s):  
Life Cycle ◽  
Western Blotting ◽  
Vegetative Growth ◽  
Tetrahymena Thermophila ◽  
Ciliated Protozoan ◽  
Active Chromatin ◽  
Somatic Nucleus ◽  
Vegetative Cells ◽  
Low Levels

Vegetative cells of the ciliated protozoan Tetrahymena thermophila contain a transcriptionally active macronucleus and a transcriptionally inert micronucleus. During vegetative growth, macronuclear histones H2A and H2B and micronuclear H2A are ubiquitinated. Despite differences in function, macro- and micro-nuclei are related. During conjugation (the sexual phase of the life cycle in Tetrahymena), postzygotic division products of micronuclei give rise to new micro- and macro-nuclei. Using an anti-ubiquitin antibody in Western blotting experiments, we determined the levels of ubiquitinated histones in new macro- and micro-nuclei at various times during conjugation. Very soon after the second postzygotic division (approximately 8 h) when new macronuclei begin to synthesize RNA, ubiquitinated H2B and polyubiquitinated H2A are present. At this time micronuclei have only low levels of ubiquitinated H2A. During later stages of conjugation (15 h), the level of polyubiquitinated H2A decreases, while ubiquitinated H2B increases in developing new macronuclei, attaining levels of ubiquitinated H2B approaching that of parental macronuclei. Ubiquitinated histones are not detectable in the 15-h micronuclei. These results show that ubiquitination of H2B coincides with the transformation of an inert germinal nucleus into that of a transcriptionally active somatic nucleus, suggesting that ubiquitinated H2B has a role in maintaining the transcriptionally active chromatin state.Key words: histone ubiquitination, Tetrahymena thermophila, chromatin, transcription.

Ultrastructural analysis of “Sensory” surface nerve endings and “putative” neurotransmitter sites in Schistosoma mansoni Miracidia

1989 ◽  
Vol 47 ◽  
pp. 962-963
Author(s):  
Betty Ruth Jones ◽  
Steve Chi-Tang Pan
Keyword(s):  
Nervous System ◽  
Life Cycle ◽  
Schistosoma Mansoni ◽  
Snail Host ◽  
Complex Life Cycle ◽  
Rational Approach ◽  
Effective Control ◽  
The Social ◽  
Social And Economic Development ◽  
Basic Biology

INTRODUCTION: Schistosomiasis has been described as “one of the most devastating diseases of mankind, second only to malaria in its deleterious effects on the social and economic development of populations in many warm areas of the world.” The disease is worldwide and is probably spreading faster and becoming more intense than the overall research efforts designed to provide the basis for countering it. Moreover, there are indications that the development of water resources and the demands for increasing cultivation and food in developing countries may prevent adequate control of the disease and thus the number of infections are increasing.Our knowledge of the basic biology of the parasites causing the disease is far from adequate. Such knowledge is essential if we are to develop a rational approach to the effective control of human schistosomiasis. The miracidium is the first infective stage in the complex life cycle of schistosomes. The future of the entire life cycle depends on the capacity and ability of this organism to locate and enter a suitable snail host for further development, Little is known about the nervous system of the miracidium of Schistosoma mansoni and of other trematodes. Studies indicate that miracidia contain a well developed and complex nervous system that may aid the larvae in locating and entering a susceptible snail host (Wilson, 1970; Brooker, 1972; Chernin, 1974; Pan, 1980; Mehlhorn, 1988; and Jones, 1987-1988).

A freeze-fracture-etched study of the physarum polycephalum plasma membrane during early formation of the macroplasmodial stage

1993 ◽  
Vol 51 ◽  
pp. 346-347
Author(s):  
Randolph W. Taylor ◽  
Henrie Treadwell
Keyword(s):  
Plasma Membrane ◽  
Life Cycle ◽  
Growth Phase ◽  
Filter Paper ◽  
Physarum Polycephalum ◽  
Freeze Fracture ◽  
Petri Dish ◽  
Wire Screen ◽  
Wide Mouth ◽  
Sterile Filter

The plasma membrane of the Slime Mold, Physarum polycephalum, process unique morphological distinctions at different stages of the life cycle. Investigations of the plasma membrane of P. polycephalum, particularly, the arrangements of the intramembranous particles has provided useful information concerning possible changes occurring in higher organisms. In this report Freeze-fracture-etched techniques were used to investigate 3 hours post-fusion of the macroplasmodia stage of the P. polycephalum plasma membrane.Microplasmodia of Physarum polycephalum (M3C), axenically maintained, were collected in mid-expotential growth phase by centrifugation. Aliquots of microplasmodia were spread in 3 cm circles with a wide mouth pipette onto sterile filter paper which was supported on a wire screen contained in a petri dish. The cells were starved for 2 hrs at 24°C. After starvation, the cells were feed semidefined medium supplemented with hemin and incubated at 24°C. Three hours after incubation, samples were collected randomly from the petri plates, placed in plancettes and frozen with a propane-nitrogen jet freezer.

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