scholarly journals COMPLEMENTATION AND PRELIMINARY LINKAGE ANALYSIS OF ZYGOTE MATURATION MUTANTS OF THE HOMOTHALLIC ALGA, CHLAMYDOMONAS MONOICA

Genetics ◽  
1983 ◽  
Vol 103 (3) ◽  
pp. 429-445
Author(s):  
Karen P VanWinkle-Swift ◽  
Cynthia G Burrascano
Keyword(s):  
Cell Growth ◽  
Linkage Analysis ◽  
Ultraviolet Irradiation ◽  
Nuclear Genome ◽  
Pair Formation ◽  
Tetrad Analysis ◽  
Mutant Strains ◽  
Complementation Groups ◽  
Chlamydomonas Monoica ◽  
Zygospore Wall

ABSTRACT Sexual reproduction in Chlamydomonas monoica is homothallic: pair formation and cell fusion occur in clonal culture and give rise to a heavily walled diploid zygospore. During maturation of the young zygote, a distinctive "primary zygote wall" is released before the development of the highly reticulate zygospore wall. Using ethyl methanesulfonate and ultraviolet irradiation as mutagens, we have isolated 19 maturation-defective (zym) mutant strains which upon self-mating produce inviable zygotes. These zygotes fail to release a primary zygote wall, fail to develop the normal zygospore wall, and eventually undergo spontaneous lysis. In nearly all cases, the mutations appear to be expressed only in the diploid zygote; pleiotropic effects on vegetative cell growth or morphology are not evident.—Complementation testing performed on 17 of these mutants indicates that all are recessive and that they define seven distinct complementation groups. Preliminary tetrad analysis of two-factor and multifactor zym crosses provides no evidence for physical clustering of the maturation genes, and instead suggests that they are widely distributed throughout the nuclear genome.

The Chlamydomonas Zygospore: Mutant Strains of Chlamydomonas monoica Blocked in Zygospore Morphogenesis Comprise 46 Complementation Groups

Genetics ◽  
1998 ◽  
Vol 148 (1) ◽  
pp. 131-137
Author(s):  
Karen VanWinkle-Swift ◽  
Kristin Baron ◽  
Alexander McNamara ◽  
Peter Minke ◽  
Cynthia Burrascano ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Molecular Analysis ◽  
Ultraviolet Irradiation ◽  
Nitrogen Starvation ◽  
Methyl Methanesulfonate ◽  
Present Collection ◽  
Mutant Strains ◽  
Complementation Groups ◽  
Chlamydomonas Monoica ◽  
Mutant Collection

Abstract Chlamydomonas monoica undergoes homothallic sexual reproduction in response to nitrogen starvation. Mating pairs are established in clonal culture via flagellar agglutination and fuse by way of activated mating structures to form the quadriflagellate zygote. The zygote further matures into a dormant diploid zygospore through a series of events that we collectively refer to as zygosporulation. Mutants that arrest development prior to the completion of zygosporulation have been obtained through the use of a variety of mutagens, including ultraviolet irradiation, 5-fluorodeoxyuridine, ethyl methanesulfonate, and methyl methanesulfonate. Complementation analysis indicates that the present mutant collection includes alleles affecting 46 distinct zygote-specific functions. The frequency with which alleles at previously defined loci have been recovered in the most recent mutant searches suggests that as many as 30 additional zygote-specific loci may still remain to be identified. Nevertheless, the present collection should provide a powerful base for ultrastructural, biochemical, and molecular analysis of zygospore morphogenesis and dormancy in Chlamydomonas.

scholarly journals OMNIPOTENT SUPPRESSORS EFFECTIVE IN Ψ+ STRAINS OF SACCHAROMYCES CEREVISIAE: RECESSIVENESS AND DOMINANCE

Genetics ◽  
1984 ◽  
Vol 107 (2) ◽  
pp. 219-230
Author(s):  
Bun-Ichiro Ono ◽  
Nozomi Moriga ◽  
Kiyomi Ishihara ◽  
Junpei Ishiguro ◽  
Yumiko Ishino ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Growth ◽  
Linkage Analysis ◽  
Ribosomal Protein ◽  
Suppressor Mutations ◽  
Complementation Groups

ABSTRACT We have characterized recessive and dominant omnipotent suppressor mutations obtained by conversion of the leu2-1 UAA mutation and the met8-UAG mutation in a ψ+ strain of Saccharomyces cerevisiae. The suppressors that act recessively upon these markers fell into two complementation groups; the sup47 and sup36 suppressors show linkage to the tyr1 locus and the aro1 locus, respectively. Of the suppressors acting dominantly upon both markers, those linked to the tyr1 locus are alleles of the SUP46 ribosomal mutation. The sup47 suppressors differ from the SUP46 suppressors not only in their suppressor activities in heterozygous diploids but also in their map positions relative to the tyr1 locus and their effects on the S11 ribosomal protein. The remaining dominant suppressors are not alleles of sup36 as judged by linkage analysis. The recessive suppressors and the dominant suppressors also differ in their effects on cell growth.

Multiple regulatory genes control expression of a gene family during development of Dictyostelium discoideum

1986 ◽  
Vol 6 (12) ◽  
pp. 4353-4361
Author(s):  
S Alexander ◽  
A M Cibulsky ◽  
S D Cuneo
Keyword(s):  
Gene Family ◽  
Dictyostelium Discoideum ◽  
Regulatory Genes ◽  
Developmental Expression ◽  
Developmentally Regulated ◽  
Suppressor Activity ◽  
Normal Expression ◽  
Mutant Strains ◽  
Complementation Groups ◽  
In Trans

Mutant strains of Dictyostelium discoideum carrying dis mutations fail to transcribe specifically the family of developmentally regulated discoidin lectin genes during morphogenesis. The phenotypes of these mutants strongly suggested that the mutations reside in regulatory genes. Using these mutant strains, we showed that multiple regulatory genes are required for the expression of the lectin structural genes and that these regulatory genes (the dis+ alleles) act in trans to regulate this gene family. These regulatory genes fall into two complementation groups (disA and disB) and map to linkage groups II and III, respectively. A further regulatory locus was defined by the identification of an unlinked supressor gene, drsA (discoidin restoring), which is epistatic to disB, but not disA, and results in the restoration of lectin expression in cells carrying the disB mutation. Mutant cells carrying the drsA allele express the discoidin lectin gene family during growth and development, in contrast to wild-type cells which express it only during development. Therefore, the suppressor activity of the drsA allele appears to function by making the expression of the discoidin lectins constitutive and no longer strictly developmentally regulated. The data indicate that normal expression of the discoidin lectins is dependent on the sequential action of the disB+, drsA+, and disA+ gene products. Thus, we described an interacting network of regulatory genes which in turn controls the developmental expression of a family of genes during the morphogenesis of D. discoideum.

scholarly journals Influence of Titanium Oxide Pillar Array Nanometric Structures and Ultraviolet Irradiation on the Properties of the Surface of Dental Implants—A Pilot Study

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1458 ◽  
Author(s):  
Leon-Ramos ◽  
Diosdado-Cano ◽  
López-Santos ◽  
Barranco ◽  
Torres-Lagares ◽  
...  
Keyword(s):  
Contact Angle ◽  
Cell Growth ◽  
Dental Implants ◽  
Titanium Oxide ◽  
Ultraviolet Irradiation ◽  
Photoelectron Spectroscopy ◽  
Titanium Implants ◽  
Microwave Source ◽  
Pillar Array ◽  
X Ray

Aim: Titanium implants are commonly used as replacement therapy for lost teeth and much current research is focusing on the improvement of the chemical and physical properties of their surfaces in order to improve the osseointegration process. TiO2, when it is deposited in the form of pillar array nanometric structures, has photocatalytic properties and wet surface control, which, together with UV irradiation, provide it with superhydrophilic surfaces, which may be of interest for improving cell adhesion on the peri-implant surface. In this article, we address the influence of this type of surface treatment on type IV and type V titanium discs on their surface energy and cell growth on them. Materials and methods: Samples from titanium rods used for making dental implants were used. There were two types of samples: grade IV and grade V. In turn, within each grade, two types of samples were differentiated: untreated and treated with sand blasting and subjected to double acid etching. Synthesis of the film consisting of titanium oxide pillar array structures was carried out using plasma-enhanced chemical vapor deposition equipment. The plasma was generated in a quartz vessel by an external SLAN-1 microwave source with a frequency of 2.45 GHz. Five specimens from each group were used (40 discs in total). On the surfaces to be studied, the following determinations were carried out: (a) X-ray photoelectron spectroscopy, (b) scanning electron microscopy, (c) energy dispersive X-ray spectroscopy, (d) profilometry, (e) contact angle measurement or surface wettability, (f) progression of contact angle on applying ultraviolet irradiation, and (g) a biocompatibility test and cytotoxicity with cell cultures. Results: The application of ultraviolet light decreased the hydrophobicity of all the surfaces studied, although it did so to a greater extent on the surfaces with the studied modification applied, this being more evident in samples manufactured in grade V titanium. In samples made in grade IV titanium, this difference was less evident, and even in the sample manufactured with grade IV and SLA treatment, the application of the nanometric modification of the surface made the surface optically less active. Regarding cell growth, all the surfaces studied, grouped in relation to the presence or not of the nanometric treatment, showed similar growth. Conclusions. Treatment of titanium oxide surfaces with ultraviolet irradiation made them change temporarily into superhydrophilic ones, which confirms that their biocompatibility could be improved in this way, or at least be maintained.

Improvement in γ-decalactone production by Yarrowia sp. after genome shuffling

2014 ◽  
Vol 68 (8) ◽  
Author(s):  
Yu-Ping Zhao ◽  
Xiao-Qing Mu ◽  
Yan Xu
Keyword(s):  
Cell Growth ◽  
Genome Shuffling ◽  
Fermentation Medium ◽  
Fatty Acyl ◽  
Culture Collection ◽  
Fermentation Time ◽  
Mutant Strains ◽  
Protoplast Preparation ◽  
Acyl Coa Oxidase ◽  
Initial Strains

AbstractIn this study, a modified genome shuffling method was used to improve γ-decalactone (GDL) production of Yarrowia sp. China General Microbiological Culture Collection Center (CGMCC 2.1405). Five UV mutant strains with higher GDL production or shorter fermentation time were selected as the initial strains for genome shuffling. Conditions of protoplast preparation, regeneration, inactivation, fusion, sporulation of recombinant fusants and ascospore isolation were optimized. Four hereditarily stable haploid recombinants with high GDL production were obtained by three rounds of genome shuffling. Among them, a high GDL-producing recombinant, G3-3.21, producing 3.75 g L−1 of GDL in the fermentation medium after 64 h was obtained. This value is 6.54-fold higher than that of the parent strains CGMCC 2.1405, at the peak production shortened by 8 h. Mathematical kinetic models of CGMCC 2.1405 and G3-3.21 were established to well predict the cell growth and GDL production. The cell growth of G3-3.21 was significantly faster than that of CGMCC 2.1405. The product synthesis constant associated with the strain growth of G3-3.21 was higher than that associated with CGMCC 2.1405. Long-chain fatty-acyl-CoA oxidase activities of G3-3.21 were 833 mU mg−1 and 6.83 times higher than that of CGMCC 2.1405.

scholarly journals Multiple regulatory genes control expression of a gene family during development of Dictyostelium discoideum.

1986 ◽  
Vol 6 (12) ◽  
pp. 4353-4361 ◽  
Author(s):  
S Alexander ◽  
A M Cibulsky ◽  
S D Cuneo
Keyword(s):  
Gene Family ◽  
Dictyostelium Discoideum ◽  
Regulatory Genes ◽  
Developmental Expression ◽  
Developmentally Regulated ◽  
Suppressor Activity ◽  
Normal Expression ◽  
Mutant Strains ◽  
Complementation Groups ◽  
In Trans

Mutant strains of Dictyostelium discoideum carrying dis mutations fail to transcribe specifically the family of developmentally regulated discoidin lectin genes during morphogenesis. The phenotypes of these mutants strongly suggested that the mutations reside in regulatory genes. Using these mutant strains, we showed that multiple regulatory genes are required for the expression of the lectin structural genes and that these regulatory genes (the dis+ alleles) act in trans to regulate this gene family. These regulatory genes fall into two complementation groups (disA and disB) and map to linkage groups II and III, respectively. A further regulatory locus was defined by the identification of an unlinked supressor gene, drsA (discoidin restoring), which is epistatic to disB, but not disA, and results in the restoration of lectin expression in cells carrying the disB mutation. Mutant cells carrying the drsA allele express the discoidin lectin gene family during growth and development, in contrast to wild-type cells which express it only during development. Therefore, the suppressor activity of the drsA allele appears to function by making the expression of the discoidin lectins constitutive and no longer strictly developmentally regulated. The data indicate that normal expression of the discoidin lectins is dependent on the sequential action of the disB+, drsA+, and disA+ gene products. Thus, we described an interacting network of regulatory genes which in turn controls the developmental expression of a family of genes during the morphogenesis of D. discoideum.

An introduction to the genetics of the fungus Coniochaeta veluitina

1969 ◽  
Vol 47 (7) ◽  
pp. 1019-1026 ◽  
Author(s):  
F. Cooke ◽  
H. Tan ◽  
H. M. Good
Keyword(s):  
Ultraviolet Irradiation ◽  
Linkage Groups ◽  
Genetic Analyses ◽  
Mutant Strains ◽  
Made In

The fungus Coniochaeta velutina (Fuckel) Munk., which inhabits defective xylem in maple trees, has been developed for a joint genetical and plant pathological program. This paper describes progress made in the genetical aspect of the problem. From the more than 80 mutants forms which have been isolated after ultraviolet irradiation, 34 have been analyzed genetically by random spore analysis. Many of the mutant strains were incapable of acting as protoperithecial parents in crosses, thus limiting the number of crosses which could be made. Three linkage groups have been discovered, but many of the genes investigated showed no linkage with any other. This finding is in keeping with similar genetic analyses with other fungi.Linkage between the two pyrimidine-requiring mutants in Coniochaeta parallels a similar finding in Neurospora.

scholarly journals A suppressor of a mating-type limited zygotic lethal allele also suppresses uniparental chloroplast gene transmission in Chlamydomonas monoica.

Genetics ◽  
1994 ◽  
Vol 136 (3) ◽  
pp. 867-877
Author(s):  
K VanWinkle-Swift ◽  
R Hoffman ◽  
L Shi ◽  
S Parker
Keyword(s):  
Chloroplast Dna ◽  
Mating Type ◽  
Uniparental Inheritance ◽  
Chloroplast Gene ◽  
Suppressor Mutations ◽  
Chloroplast Genomes ◽  
Mutant Strains ◽  
Resistance Markers ◽  
Lethal Allele ◽  
Chlamydomonas Monoica

Abstract Uniparental inheritance of Chlamydomonas chloroplast genes is thought to involve modification of maternal (mt+) chloroplast genomes to protect against a nuclease that is activated after gamete fusion. The mating-type limited mtl-1 mutant strain of Chlamydomonas monoica is unable to protect mt(+)-derived chloroplast DNA. Zygotes homozygous for mtl-1 lose all chloroplast DNA and fail to germinate. We have selected for suppression of this zygote-specific lethality, and have obtained 20 mutant strains that produce viable homozygotes despite the continued presence of the mtl-1 allele. Genetic analysis indicates that the suppressor mutations are all recessive alleles at a single locus (sup-1) which is unlinked to mtl-1. Crosses between sup-1 strains carrying distinctive chloroplast antibiotic resistance markers also show predominantly biparental chloroplast gene transmission. Chloroplast nucleoids of both parental origins (stained with the DNA-specific fluorochrome, DAPI) are retained in the zygotes homozygous for sup-1. The data are compatible with the idea that the sup-1 (suppressor of uniparental inheritance) locus may encode a chloroplast DNA nuclease that is expressed from both parental genomes.

scholarly journals ISOLATION AND GENETIC ANALYSIS OF MUTANT STRAINS OF CHLAMYDOMONAS REINHARDI DEFECTIVE IN GAMETIC DIFFERENTIATION

Genetics ◽  
1976 ◽  
Vol 82 (2) ◽  
pp. 169-186
Author(s):  
Ursula W Goodenough ◽  
Carol Hwang ◽  
Howard Martin
Keyword(s):  
Genetic Analysis ◽  
Cell Fusion ◽  
Mating Type ◽  
Normal Growth ◽  
The Other ◽  
Genetic Dissection ◽  
Structural Studies ◽  
Tetrad Analysis ◽  
Mating Structure ◽  
Mutant Strains

ABSTRACT Impotent mutant strains of Chlamydomonas reinhardi, mating-type (mt) plus, are described that have normal growth and motility but fail to differentiate into normal gametes. Procedures for their isolation and their genetic analysis are described. Five of the imp strains (imp-2, imp-5, imp-6, imp-7, and imp-8) exhibit no flagellar agglutination when mixed with mt  - or mt  + gametes; these strains have been induced to form rare zygotes with mt  - gametes and the mutations are shown to be unlinked to the mt locus (with the possible exception of imp-7). Two of the strains (imp-3 and imp-4) carry leaky mutations that affect cell fusion; neither mutation is found by tetrad analysis to be linked to mt or to the other. Cells of the imp-1 strain agglutinate well with mt  - gametes and active agglutination continues for up to 48 hours, but cell fusion occurs only very rarely. Analysis of these rare zygotes indicates that imp-1 is closely linked to the mt  + locus, and fine-structural studies reveal that imp-1gametes produce a mutant mating structure involved in zygotic cell fusion. The development of sexuality in C. reinhardi therefore appears amenable to genetic dissection.

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