Genetic analysis of developmental mechanisms in Hydra. IV. Characterization of a nematocyst-deficient strain

1978 ◽  
Vol 30 (1) ◽  
pp. 175-185 ◽  
Author(s):  
T. Fujisawa ◽  
T. Sugiyama
Keyword(s):  
Genetic Analysis ◽  
Normal Level ◽  
The Body ◽  
Normal Rate ◽  
Wild Type ◽  
Head Region ◽  
Developmental Defects ◽  
Developmental Mechanisms ◽  
Body Column

The authors have previously found that mutant hydra strains showing various types of developmental defects can be isolated through sexual inbreeding of wild hydra. One such defective strain, called nem-4, contains virtually no stenoteles, one of the four types of nematocysts present in hydra, in its tentacles. However, stenoteles are present at a normal level in the body column of this strain, and they are turned over also at a normal rate. Grafting experiments between the head region of nem-4 hydra and the body column of wild type hydra (and vice versa) showed that wild type stenotele nematocytes can move into nem-4 tentacles but that nem-4 stenotele nematocytes can not move into the wild type tentacles. These observations suggest that the stenotele nematocytes are produced normally by differentiation from the interstitial cells in the body column of nem-4 hydra, but that they are somehow prevented from migrating into the tentacles in this strain.

Characterization of the Role of the FluG Protein in Asexual Development of Aspergillus nidulans

Genetics ◽  
2001 ◽  
Vol 158 (3) ◽  
pp. 1027-1036 ◽  
Author(s):  
Cletus A D'Souza ◽  
Bee Na Lee ◽  
Thomas H Adams
Keyword(s):  
Aspergillus Nidulans ◽  
Negative Influence ◽  
Asexual Development ◽  
Wild Type ◽  
Significant Similarity ◽  
Developmental Defects ◽  
Asexual Sporulation ◽  
Type Strains

Abstract We showed previously that a ΔfluG mutation results in a block in Aspergillus nidulans asexual sporulation and that overexpression of fluG activates sporulation in liquid-submerged culture, a condition that does not normally support sporulation of wild-type strains. Here we demonstrate that the entire N-terminal region of FluG (∼400 amino acids) can be deleted without affecting sporulation, indicating that FluG activity resides in the C-terminal half of the protein, which bears significant similarity with GSI-type glutamine synthetases. While FluG has no apparent role in glutamine biosynthesis, we propose that it has an enzymatic role in sporulation factor production. We also describe the isolation of dominant suppressors of ΔfluG(dsg) that should identify components acting downstream of FluG and thereby define the function of FluG in sporulation. The dsgA1 mutation also suppresses the developmental defects resulting from ΔflbA and dominant activating fadA mutations, which both cause constitutive induction of the mycelial proliferation pathway. However, dsgA1 does not suppress the negative influence of these mutations on production of the aflatoxin precursor, sterigmatocystin, indicating that dsgA1 is specific for asexual development. Taken together, our studies define dsgA as a novel component of the asexual sporulation pathway.

scholarly journals Genetic analysis of the Arabidopsis TIR1/AFB auxin receptors reveals both overlapping and specialized functions

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Michael J Prigge ◽  
Matthieu Platre ◽  
Nikita Kadakia ◽  
Yi Zhang ◽  
Kathleen Greenham ◽  
...  
Keyword(s):  
Genetic Analysis ◽  
Early Embryo ◽  
Wild Type ◽  
The Family ◽  
Dependent Inhibition ◽  
Root Gravitropism ◽  
Specialized Function ◽  
Mutant Lines

The TIR1/AFB auxin co-receptors mediate diverse responses to the plant hormone auxin. The Arabidopsis genome encodes six TIR1/AFB proteins representing three of the four clades that were established prior to angiosperm radiation. To determine the role of these proteins in plant development we performed an extensive genetic analysis involving the generation and characterization of all possible multiply-mutant lines. We find that loss of all six TIR1/AFB proteins results in early embryo defects and eventually seed abortion, and yet a single wild-type allele of TIR1 or AFB2 is sufficient to support growth throughout development. Our analysis reveals extensive functional overlap between even the most distantly related TIR1/AFB genes except for AFB1. Surprisingly, AFB1 has a specialized function in rapid auxin-dependent inhibition of root growth and early phase of root gravitropism. This activity may be related to a difference in subcellular localization compared to the other members of the family.

scholarly journals Genetic analysis of developmental mechanisms in Hydra. II. Isolation and characterization of an interstitial cell-deficient strain

1978 ◽  
Vol 29 (1) ◽  
pp. 35-52 ◽  
Author(s):  
T. Sugiyama ◽  
T. Fujisawa
Keyword(s):  
Genetic Analysis ◽  
Mutant Strain ◽  
Interstitial Cell ◽  
Interstitial Cells ◽  
Nerve Cells ◽  
Isolation And Characterization ◽  
Developmental Mechanisms ◽  
Hydra Magnipapillata

A mutant strain (nf-I) of Hydra magnipapillata was isolated that contained no interstitial cells, nerve cells or nematocytes. This strain appeared spontaneously in a sexually inbred clone of hydra, and it was recognized by its inability to eat. When force-fed, however, it grew, multiplied by budding and regenerated. In this and in many other respects, nf-I was very similar to the interstitial cell-deficient strain produced by Campbell (1976) by means of colchicine. A chimera strain was produced by the reintroduction of interstitial cells from another strain into nf-I. The properties of nf-I, the chimera and other related strains were examined, and the possible roles that the interstitial cells and the nerve cells play in growth and morphogenesis of hydra are discussed.

scholarly journals Differential expression of BMP antagonists, gremlin and noggin in hydra: antagonism between Wnt and BMP pathways

2019 ◽  
Author(s):  
Krishnapati Lakshmi Surekha ◽  
Samiksha Khade ◽  
Diptee Trimbake ◽  
Rohan Patwardhan ◽  
Siva Kumar Nadimpalli ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
The Body ◽  
Head Region ◽  
Down Regulation ◽  
Hydra Vulgaris ◽  
Basal Disc ◽  
Bmp Pathway ◽  
Summary Statement ◽  
Bmp Antagonists ◽  
Body Column

AbstractMechanisms regulating BMP and Wnt signaling pathways have been widely studied in many organisms. One of the mechanisms by which these pathways are regulated is by binding of extracellular ligands. In the present study, we report studies with two BMP antagonists, gremlin and noggin from Hydra vulgaris Ind-Pune and demonstrate antagonistic relationship between BMP and Wnt pathways. Gremlin was ubiquitously expressed from the body column to head region except in the basal disc and hypostome. During budding, gremlin was expressed predominantly in the budding region suggesting a possible role in budding; this was confirmed in polyps with different stages of buds. Noggin, on the other hand, was predominantly expressed in the endoderm of hypostome, base of the tentacles, lower body column and at the basal disc in whole polyps. During budding, noggin was expressed at the sites of emergence of tentacles suggesting a role in tentacle formation. This was confirmed in alsterpaullone-treated polyps, which showed noggin expression as distinct spots where ectopic organizers and ectopic tentacles eventually formed. Using RT-PCR, we found that up-regulation of Wnt is accompanied with down-regulation of BMP5-8b demonstrating antagonism between the two pathways. Down-regulation of noggin and gremlin, however, occurred only after 24 h recovery. The data suggest that inhibition of BMP pathway by Wnt signaling in hydra does not directly involve noggin and gremlin. Our findings indicate that the BMP/Noggin antagonism evolved early for setting up and/or maintaining the head organizer while involvement of these BMP antagonists during vertebrate axial patterning are recent evolutionary acquisitions.Summary statementWe show that setting up of the Organizer by BMP/Noggin antagonism and role of BMP inhibitors in tissue patterning are evolutionarily ancient, probably arising for the first time in hydra

Characterization of the head organizer in hydra

Development ◽  
2002 ◽  
Vol 129 (4) ◽  
pp. 875-884 ◽  
Author(s):  
Mariya Broun ◽  
Hans R. Bode
Keyword(s):  
Organizer Region ◽  
Apical Part ◽  
The Body ◽  
Central Process ◽  
Axial Patterning ◽  
Secondary Axis ◽  
Head Formation ◽  
Body Column ◽  
Self Organizing

A central process in the maintenance of axial patterning in the adult hydra is the head activation gradient, i.e. the potential to form a secondary axis, which is maximal in the head and is graded down the body column. Earlier evidence suggested that this gradient was based on a single parameter. Using transplantation experiments, we provide evidence that the hypostome, the apical part of the head, has the characteristics of an organizer in that it has the capacity to induce host tissue to form most of the second axis. By contrast, tissue of the body column has a self-organizing capacity, but not an inductive capacity. That the inductive capacity is confined to the hypostome is supported by experiments involving a hypostome-contact graft. The hypostome, but not the body column, transmits a signal(s) leading to the formation of a second axis. In addition, variations of the transplantation grafts and hypostome-contact grafts provide evidence for several characteristics of the organizer. The inductive capacity of the head and the self-organizing capacity of the body column are based on different pathways. Head inhibition, yya signal produced in the head and transmitted to the body column to prevent head formation, represses the effect of the inducing signal by interfering with formation of the hypostome/organizer. These results indicate that the organizer characteristics of the hypostome of an adult hydra are similar to those of the organizer region of vertebrate embryos. They also indicate that the Gierer-Meinhardt model provides a reasonable framework for the mechanisms that underlie the organizer and its activities. In addition, the results suggest that a region of an embryo or adult with the characteristics of an organizer arose early in metazoan evolution.

Genetic analysis of developmental mechanisms in hydra

Development ◽  
1977 ◽  
Vol 42 (1) ◽  
pp. 65-77
Author(s):  
Tsutomu Sugiyama ◽  
Toshitaka Fujisawa
Keyword(s):  
Epithelial Cells ◽  
Genetic Analysis ◽  
Mutant Strain ◽  
Interstitial Cells ◽  
Nerve Cells ◽  
Abnormal Development ◽  
Wild Type ◽  
Developmental Mechanisms ◽  
Head Formation

Mutant hydra strains showing abnormal development can be isolated through sexual inbreeding of wild hydra. One such mutant strain, called reg-16, regenerates tentacles very poorly following amputation of the head and foot. Tentacle regeneration, however, is significantly enhanced by subdividing the regenerating fragment longitudinally. Lateral tissue implants that induce head formation in wild-type hydra either regress or induce foot formation in reg-16 polyps. These results suggest that regeneration deficiency in reg-16 is due to a defective polarity gradient. A chimaeric strain of hydra was produced by combining interstitial cells (and thus their differentiation products, nerve cells and nematocytes) of reg-16 hydra with epithelial cells of another strain which is capable of normal regeneration. The chimaeras regenerate normally, suggesting that the defect of reg-16 is not located in the interstitial or nerve cells.

Inheritance and characterization of a dark-germinating, light-inhibited mutant in the fern Ceratopteris richardii

1991 ◽  
Vol 69 (12) ◽  
pp. 2616-2619 ◽  
Author(s):  
Rodney J. Scott ◽  
Leslie G. Hickok
Keyword(s):  
Genetic Analysis ◽  
Key Words ◽  
Nuclear Gene ◽  
Sexual Cycle ◽  
Wild Type ◽  
Ceratopteris Richardii ◽  
Mutant Selection ◽  
Light Inhibition ◽  
Selection For

Selection for a dark-germinating mutant was made with X-irradiated spores of Ceratopteris richardii. A single mutant line (HαDG1) was recovered and analyzed for its germination responses under different light–dark treatments and for transmission of the trait through a complete sexual cycle. HαDG1 was characterized by two phenotypes, dark germination and light inhibition of germination. These responses were exactly opposite from wild-type responses. The level of dark germination for a particular spore batch was stable through time, whereas light inhibition was unstable with time. Genetic analysis indicated that both phenotypes are associated with a single nuclear gene mutation that has been designated dkg1. Key words: fern, photomorphogenesis, mutant selection, germination, spore.

Analysis of gene expression during development in the homeotic mutant Contrabithorax of Drosophila melanogaster

Development ◽  
1975 ◽  
Vol 34 (1) ◽  
pp. 19-31
Author(s):  
Gines Morata
Keyword(s):  
Gene Expression ◽  
Drosophila Melanogaster ◽  
Genetic Analysis ◽  
Normal Level ◽  
X Rays ◽  
Wild Type ◽  
Homeotic Transformation ◽  
Homeotic Mutant ◽  
A Cell ◽  
Final Expression

Contrabithorax, a mutant of the bithorax system in Drosophila melanogaster produces a partial homeotic transformation of mesothorax (wing) into metathorax (haltere). The wing of a fly homozygous or heterozygous for the mutant is a mosaic of wing and haltere structures. A genetic analysis of the mutant suggests that its phenotype is due to some form of derepression in the wing of two other genes of the bithorax system (bithorax and postbithorax) which are not normally active there. This repression is not complete. The activity of the two genes is below the normal level resulting in only a partial transformation of wing into haltere. Clones of marked cells were generated by X-rays and were found to include both transformed (haltere) and untransformed (wing) territory; this was true even for those generated late in development. Thus the final expression of a cell depends not on its immediate ancestry but perhaps on the level of the products of the wild-type alleles of bithorax and postbithorax.

scholarly journals ISOLATION AND CHARACTERIZATION OF LIGHT-INSENSITIVE MUTANTS OF NEUROSPORA CRASSA

Genetics ◽  
1983 ◽  
Vol 104 (1) ◽  
pp. 11-21
Author(s):  
John Paietta ◽  
Malcolm L Sargent
Keyword(s):  
Genetic Analysis ◽  
Neurospora Crassa ◽  
Blue Light ◽  
Light Sensitivity ◽  
Phase Shifting ◽  
Nuclear Genes ◽  
Wild Type ◽  
Linkage Groups ◽  
Isolation And Characterization

ABSTRACT As part of a genetic analysis of blue light photoreception in Neurospora, three mutants were isolated that do not exhibit photosuppression of circadian conidiation, i.e., they show periodic conidiation in constant light. The mutations have been given the designations lis-1, lis-2 and lis-3 ("light insensitive"). The three mutations segregate as single nuclear genes, are nonallelic and are recessive to wild type in heterokaryon tests. The linkage groups of the mutations are as follows: lis-1, I; lis-2, VI; and lis-3, V. The light -insensitive phenotype of the mutants is restricted to the photosuppression response; other responses such as photoinduced phase shifting of the conidiation rhythm and photoinduced carotenogenesis are not altered. The physiological or biochemical defects of the mutants have not been established, but they are not similar to previous reported cases (i.e., rib and poky) in which a reduction in light sensitivity has been observed.

scholarly journals Identification and Characterization of a Novel Adhesin Unique to Oral Fusobacteria

2005 ◽  
Vol 187 (15) ◽  
pp. 5330-5340 ◽  
Author(s):  
Yiping W. Han ◽  
Akihiko Ikegami ◽  
Chythanya Rajanna ◽  
Hameem I. Kawsar ◽  
Yun Zhou ◽  
...  
Keyword(s):  
Chinese Hamster ◽  
Fusobacterium Nucleatum ◽  
The Body ◽  
Surface Proteins ◽  
Wild Type ◽  
Kb Cells ◽  
Ovarian Cells ◽  
Molecular Masses ◽  
Identification And Characterization

ABSTRACT Fusobacterium nucleatum is a gram-negative anaerobe that is prevalent in periodontal disease and infections of different parts of the body. The organism has remarkable adherence properties, binding to partners ranging from eukaryotic and prokaryotic cells to extracellular macromolecules. Understanding its adherence is important for understanding the pathogenesis of F. nucleatum. In this study, a novel adhesin, FadA (Fusobacterium adhesin A), was demonstrated to bind to the surface proteins of the oral mucosal KB cells. FadA is composed of 129 amino acid (aa) residues, including an 18-aa signal peptide, with calculated molecular masses of 13.6 kDa for the intact form and 12.6 kDa for the secreted form. It is highly conserved among F. nucleatum, Fusobacterium periodonticum, and Fusobacterium simiae, the three most closely related oral species, but is absent in the nonoral species, including Fusobacterium gonidiaformans, Fusobacterium mortiferum, Fusobacterium naviforme, Fusobacterium russii, and Fusobacterium ulcerans. In addition to FadA, F. nucleatum ATCC 25586 and ATCC 49256 also encode two paralogues, FN1529 and FNV2159, each sharing 31% identity with FadA. A double-crossover fadA deletion mutant, F. nucleatum 12230-US1, was constructed by utilizing a novel sonoporation procedure. The mutant had a slightly slower growth rate, yet its binding to KB and Chinese hamster ovarian cells was reduced by 70 to 80% compared to that of the wild type, indicating that FadA plays an important role in fusobacterial colonization in the host. Furthermore, due to its uniqueness to oral Fusobacterium species, fadA may be used as a marker to detect orally related fusobacteria. F. nucleatum isolated from other parts of the body may originate from the oral cavity.

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