Genetic analysis of developmental mechanisms in hydra

Development ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 123-138
Author(s):  
Jun Takano ◽  
Tsutomu Sugiyama
Keyword(s):  
Genetic Analysis ◽  
Mutant Strain ◽  
Brine Shrimp ◽  
Potential Gradient ◽  
Body Axis ◽  
Developmental Mechanisms ◽  
Effect Of Food ◽  
Potential Gradients ◽  
Very High

Effect of food was examined on the budding rate and the developmental gradients of a mutant hydra strain L4. This mutant strain has very high levels of head-inhibition potential gradient along its body axis (Takano & Sugiyama, 1983). It also has a reduced budding capacity when it is cultured using brine shrimp nauplii as food, but its budding capacity is significantly improved when a small amount of tubifex worm tissue is added to its diet of brine shrimp (Takano, 1984). To test whether or not this change of budding rate is correlated with the change in the levels of the head-activation or head-inhibition potential gradients, L4 animals were cultured on the diet of brine shrimp with or without addition of tubifex worm tissue and the budding rates and the gradient levels were examined in these animals. The results showed that food affected the budding rate in L4 without affecting its gradient levels. This suggests that the gradient levels and the budding rate in L4 are uncorrelated to each other, and that therefore the high levels of head-inhibition potential are not the cause for the low budding rate in this strain (cf., Takano & Sugiyama, 1983).

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.

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.

Measuring surface potential components necessary for transmembrane current computation using microfabricated arrays

2005 ◽  
Vol 289 (6) ◽  
pp. H2468-H2477 ◽  
Author(s):  
J. James Wiley ◽  
Raymond E. Ideker ◽  
William M. Smith ◽  
Andrew E. Pollard
Keyword(s):  
Spatial Resolution ◽  
Current Density ◽  
Potential Gradient ◽  
Electrode Spacing ◽  
Back Side ◽  
Transmembrane Current ◽  
Fine Wire ◽  
Microfabricated Arrays ◽  
Potential Gradients ◽  
Unipolar Electrograms

This study was designed to test the feasibility of using microfabricated electrodes to record surface potentials with sufficiently fine spatial resolution to measure the potential gradients necessary for improved computation of transmembrane current density. To assess that feasibility, we recorded unipolar electrograms from perfused rabbit right ventricular free wall epicardium ( n = 6) using electrode arrays that included 25-μm sensors fabricated onto a flexible substrate with 75-μm interelectrode spacing. Electrode spacing was therefore on the size scale of an individual myocyte. Signal conditioning adjacent to the sensors to control lead noise was achieved by routing traces from the electrodes to the back side of the substrate where buffer amplifiers were located. For comparison, recordings were also made using arrays built from chloridized silver wire electrodes of either 50-μm (fine wire) or 250-μm (coarse wire) diameters. Electrode separations were necessarily wider than with microfabricated arrays. Comparable signal-to-noise ratios (SNRs) of 21.2 ± 2.2, 32.5 ± 4.1, and 22.9 ± 0.7 for electrograms recorded using microfabricated sensors ( n = 78), fine wires ( n = 78), and coarse wires ( n = 78), respectively, were found. High SNRs were maintained in bipolar electrograms assembled using spatial combinations of the unipolar electrograms necessary for the potential gradient measurements and in second-difference electrograms assembled using spatial combinations of the bipolar electrograms necessary for surface Laplacian (SL) measurements. Simulations incorporating a bidomain representation of tissue structure and a two-dimensional network of guinea pig myocytes prescribed following the Luo and Rudy dynamic membrane equations were completed using 12.5-μm spatial resolution to assess contributions of electrode spacing to the potential gradient and SL measurements. In those simulations, increases in electrode separation from 12.5 to 75.0, 237.5, and 875.0 μm, which were separations comparable to the finest available with our microfabricated, fine wire, and coarse wire arrays, led to 10%, 42%, and 81% reductions in maximum potential gradients and 33%, 76%, and 96% reductions in peak-to-peak SLs. Maintenance of comparable SNRs for source electrograms was therefore important because microfabrication provides a highly attractive methods to achieve spatial resolutions necessary for improved computation of transmembrane current density.

Genetic analysis of developmental mechanisms in hydra

1986 ◽  
Vol 115 (1) ◽  
pp. 249-255 ◽  
Author(s):  
Eucaly Kobatake ◽  
Tsutomu Sugiyama
Keyword(s):  
Genetic Analysis ◽  
Developmental Mechanisms

scholarly journals Genetic and physical analyses of sister chromatid exchange in yeast meiosis

1991 ◽  
Vol 11 (12) ◽  
pp. 6328-6336
Author(s):  
H Sun ◽  
D Dawson ◽  
J W Szostak
Keyword(s):  
Genetic Analysis ◽  
Gene Conversion ◽  
Mutant Strain ◽  
Sister Chromatid ◽  
Sister Chromatid Exchange ◽  
Physical Analysis ◽  
Single Stranded Dna ◽  
Meiotic Gene ◽  
Dna Fragment ◽  
Yeast Meiosis

We have used nonessential circular minichromosomes to monitor sister chromatid exchange during yeast meiosis. Genetic analysis shows that a 64-kb circular minichromosome undergoes sister chromatid exchange during 40% of meioses. This frequency is not reduced by the presence of a homologous linear minichromosome. Furthermore, sister chromatid exchange can be stimulated by the presence of a 12-kb ARG4 DNA fragment, which contains initiation sites for meiotic gene conversion. Using physical analysis, we have directly identified a product of sister chromatid exchange: a head-to-tail dimer form of a circular minichromosome. This dimer form is absent in a rad50S mutant strain, which is deficient in processing of the ends of meiosis-specific double-stranded breaks into single-stranded DNA tails. Our studies suggest that meiotic sister chromatid exchange is stimulated by the same mechanism as meiotic homolog exchange.

scholarly journals A CIS-DOMINANT MUTATION IN ASPERGILLUS NIDULANS AFFECTING THE EXPRESSION OF THE amdS GENE IN THE PRESENCE OF MUTATIONS IN THE UNLINKED GENE, amdA

Genetics ◽  
1982 ◽  
Vol 102 (2) ◽  
pp. 139-147
Author(s):  
Michael J Hynes
Keyword(s):  
Fine Structure ◽  
Genetic Analysis ◽  
Genetic Mapping ◽  
Gene Function ◽  
The Other ◽  
Structure Mapping ◽  
Dominant Mutation ◽  
Amds Gene ◽  
Very High ◽  
New Mutations

ABSTRACT A mutant producing very high levels of the acetamidase enzyme encoded by the amdS gene has been isolated in a strain containing the amdA7 mutation, which itself causes high levels of this enzyme. Genetic analysis has shown that this mutation, designated amdI66, is adjacent to the amdS gene and is cis-dominant in its effect. The amdI66 mutation has little effect on amdS expression when present in strains not containing the amdA7 mutation. Two other amdA mutations investigated also interact with the amdI66 mutation to result in high acetamidase levels. No interaction between amdI66 and any of the other putative regulatory genes affecting amdS expression has been observed. The amdI66 mutation has been located by fine structure mapping at the extreme end of the controlling region, which has previously been defined by genetic mapping (Hynes 1979). Analysis of this region has been extended by mapping new mutations resulting in loss of amdS expression. One of these defines the most extreme site capable of mutation to loss of gene function found so far.

A New Explanation for the Osmotic Activity and Ionic Composition of Gastric Juice

1957 ◽  
Vol 192 (1) ◽  
pp. 14-22 ◽  
Author(s):  
Warren S. Rehm ◽  
Warren H. Dennis ◽  
William A. Brodsky
Keyword(s):  
Osmotic Pressure ◽  
Gastric Juice ◽  
Chemical Potential ◽  
Ionic Composition ◽  
Potential Gradient ◽  
Inorganic Ions ◽  
Parietal Cells ◽  
Inorganic Ion ◽  
Potential Gradients ◽  
Osmotic Activity

In an attempt to extend a previously proposed theory of gastric HCl production, the possibility is considered that the surface epithelial cells secrete H+ ions and the parietal cells Cl– ions and water. It is postulated that water is transported as a result of its chemical potential gradient between the interstitial fluid and the canalicular lumen of the parietal cells. It is shown that this scheme can quantitatively explain, without further postulates, the high normalities of secretion found in the glycine experiments of Teorell. However, the scheme predicts for pure gastric juice a higher osmotic pressure than that found. Furthermore, the scheme does not offer an explanation for the presence of the other inorganic ions of gastric juice. In an attempt to account for the observed osmotic pressure and the inorganic ion content of gastric juice, the implications are developed of the assumption that the Na+ ions, K+ ions and some of the secreted Cl– ions are transported across the mucosa in the direction of their electrochemical potential gradients. It is shown that the resulting scheme can account for the composition and osmotic pressure of gastric juice at least as well as any of the schemes proposed by other workers. The implications of the present scheme with respect to the problem of the production of hypertonic and hypotonic secretions are discussed.

Genetics: Genetic Analysis of Developmental Mechanisms in Drosophila

Nature ◽  
1971 ◽  
Vol 234 (5326) ◽  
pp. 187-194 ◽  
Author(s):  
HOWARD A. SCHNEIDERMAN ◽  
PETER J. BRYANT
Keyword(s):  
Genetic Analysis ◽  
Developmental Mechanisms

scholarly journals Intensive genetic analysis for Chinese patients with very high triglyceride levels: Relations of mutations to triglyceride levels and acute pancreatitis

EBioMedicine ◽  
2018 ◽  
Vol 38 ◽  
pp. 171-177 ◽  
Author(s):  
Jing-Lu Jin ◽  
Di Sun ◽  
Ye-Xuan Cao ◽  
Hui-Wen Zhang ◽  
Yuan-Lin Guo ◽  
...  
Keyword(s):  
Acute Pancreatitis ◽  
Genetic Analysis ◽  
Chinese Patients ◽  
Very High ◽  
High Triglyceride
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