scholarly journals A sex recognition glycoprotein is encoded by the plus mating-type gene fus1 of Chlamydomonas reinhardtii.

1996 ◽  
Vol 7 (8) ◽  
pp. 1235-1248 ◽  
Author(s):  
P J Ferris ◽  
J P Woessner ◽  
U W Goodenough
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Mating Type ◽  
Sex Recognition ◽  
Unicellular Green Alga ◽  
Defective Mutant ◽  
Mutant Strains ◽  
Type Gene ◽  
Fringe Proteins ◽  
Transposon Insertions ◽  
Unique Domain

Sexual fusion between plus and minus gametes of the unicellular green alga Chlamydomonas reinhardtii entails adhesion between plus-specific and minus-specific "fringe" proteins displayed on the plasma membrane of gametic mating structures. We report the identification of the gene (fus1) encoding the plus fringe glycoprotein, which resides in a unique domain of the mating-type plus (mt+) locus, and which was identified by transposon insertions in three fusion-defective mutant strains. Transformation with fus1+ restores fringe and fusion competence to these mutants and to the pseudo-plus mutant imp11 mt-, defective in minus differentiation. The fus1 gene is remarkable in lacking the codon bias found in all other nuclear genes of C. reinhardtii.

UV light-induced DNA damage detection in the unicellular green alga Chlamydomonas reinhardtii

Biologia ◽  
2008 ◽  
Vol 63 (6) ◽  
Author(s):  
Alena Hercegová ◽  
Andrea Ševčovičová ◽  
Eliška Gálová
Keyword(s):  
Dna Damage ◽  
Chlamydomonas Reinhardtii ◽  
Green Alga ◽  
Excision Repair ◽  
Biological Effects ◽  
Pyrimidine Dimer ◽  
Repair System ◽  
Pyrimidine Dimers ◽  
Unicellular Green Alga ◽  
Mutant Strains

AbstractExposure of cells to ultraviolet radiation (UVR) is one of the best studied and most used model system for the examination of the biological effects of DNA damage, its repair and tolerance. The major product after UVR treatment is cyclobutane pyrimidine dimer (TT, TC, CC). Pyrimidine dimers are repaired by a direct reversal called photoreactivation or by excision of damage in a process of nucleotide excision repair. Several methods have been developed for the detection and quantification of pyrimidine dimers in DNA. The technique of Small and Greimann, in which DNA is incubated with the pyrimidine dimer-specific endonuclease, was used for the analysis of mutant strains with impaired excision repair system of the unicellular green alga Chlamydomonas reinhardtii. Another method is based on the binding of specific monoclonal antibodies to pyrimidine dimers. The aim of our work was to compare these two techniques with the use of mutant strains of C. reinhardtii — uvsX1 and uvsX2 which are assumed to be deficient in DNA damage recognition. One of their traits was sensitivity to UVR which could be caused by breakdown of the excision repair pathway. The results suggest that the immuno-approach is suitable for the detection of DNA damage induced by UVR.

scholarly journals Gametic differentiation in Chlamydomonas reinhardtii. III. Cell wall lysis and microfilament-associated mating structure activation in wild-type and mutant strains.

1975 ◽  
Vol 67 (3) ◽  
pp. 623-637 ◽  
Author(s):  
U W Goodenough ◽  
R L Weiss
Keyword(s):  
Cell Wall ◽  
Chlamydomonas Reinhardtii ◽  
Mating Type ◽  
Experimental Manipulation ◽  
Wild Type ◽  
Opposite Mating Type ◽  
Mating Structure ◽  
Cell Wall Lysis ◽  
Gamete Formation ◽  
Mutant Strains

Cell fusion between mating type plus (mt+) and minus (mt-) gametes of Chlamydomonas reinhardtii is analyzed structurally and subjected to experimental manipulation. Cell wall lysis, a necessary prelude to fusion, is shown to require flagellar agglutination between competent gametes; glutaraldehyde-fixed gametes ("corpses") of one mating type will elicit both agglutination and cell wall lysis in the opposite mating type, whereas nonagglutinating impotent (imp) mutant strains are without effect. The fusion process is mediated by a narrow fertilization tubule which extends from the mt+ gamete and establishes contact with the mt- gamete. Formation of the tubule requires the "activation" of a specialized mating structure associated with the ml+ cell membrane; activation causes microfilaments to polymerize from the mating structure into the growing fertilization tubule. Mating structure activation is shown to depend on gametic flagellar agglutination; isoagglutination mediated by the lectin concanavalin A has no effect. Gametes carrying the imp-l mt+ mutation are able to agglutinate but not fuse with mt- cells; the imp-l gametes are shown to have structurally defective mating structures that do not generate microfilaments in response to gametic agglutination.

scholarly journals Deletion of the Schizophyllum commune Aα Locus: The Roles of Aα Y and Z Mating-Type Genes

Genetics ◽  
1996 ◽  
Vol 144 (4) ◽  
pp. 1437-1444
Author(s):  
C Ian Robertson ◽  
Kirk A Bartholomew ◽  
Charles P Novotny ◽  
Robert C Ullrich
Keyword(s):  
Mating Type ◽  
Sexual Development ◽  
Schizophyllum Commune ◽  
Mating Types ◽  
Developmental Pathway ◽  
Mating Type Gene ◽  
Mating Type Genes ◽  
Regulatory Loci ◽  
Type Gene

The Aα locus is one of four master regulatory loci that determine mating type and regulate sexual development in Schizophyllum commune. We have made a plasmid containing a URA1 gene disruption of the Aα Y1 gene. Y1 is the sole Aα gene in Aα1 strains. We used the plasmid construction to produce an Aα null (i.e., AαΔ) strain by replacing the genomic Y1 gene with URA1 in an Aα1 strain. To characterize the role of the Aα genes in the regulation of sexual development, we transformed various Aα Y and Z alleles into AαΔ strains and examined the acquired mating types and mating abilities of the transformants. These experiments demonstrate that the Aα Y gene is not essential for fungal viability and growth, that a solitary Z Aα mating-type gene does not itself activate development, that Aβ proteins are sufficient to activate the A developmental pathway in the absence of Aα proteins and confirm that Y and Z genes are the sole determinants of Aα mating type. The data from these experiments support and refine our model of the regulation of A-pathway events by Y and Z proteins.

scholarly journals Endogenous Fluctuations of DNA Topology in the Chloroplast of Chlamydomonas reinhardtii

1998 ◽  
Vol 18 (12) ◽  
pp. 7235-7242 ◽  
Author(s):  
Maria L. Salvador ◽  
Uwe Klein ◽  
Lawrence Bogorad
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Chloroplast Genome ◽  
Continuous Light ◽  
Dna Supercoiling ◽  
Dna Topology ◽  
Chloroplast Gene ◽  
Chloroplast Gene Expression ◽  
Endogenous Fluctuations ◽  
Unicellular Green Alga ◽  
In Cells

ABSTRACT DNA supercoiling in the chloroplast of the unicellular green algaChlamydomonas reinhardtii was found to change with a diurnal rhythm in cells growing in alternating 12-h dark–12-h light periods. Highest and lowest DNA superhelicities occurred at the beginning and towards the end of the 12-h light periods, respectively. The fluctuations in DNA supercoiling occurred concurrently and in the same direction in two separate parts of the chloroplast genome, one containing the genes psaB, rbcL, andatpA and the other containing the atpB gene. Fluctuations were not confined to transcribed DNA regions, indicating simultaneous changes in DNA conformation all over the chloroplast genome. Because the diurnal fluctuations persisted in cells kept in continuous light, DNA supercoiling is judged to be under endogenous control. The endogenous fluctuations in chloroplast DNA topology correlated tightly with the endogenous fluctuations of overall chloroplast gene transcription and with those of the pool sizes of most chloroplast transcripts analyzed. This result suggests that DNA superhelical changes have a role in the regulation of chloroplast gene expression in Chlamydomonas.

scholarly journals Photosymbiose — neuartige Anwendungen in der Biomedizin

BIOspektrum ◽  
2021 ◽  
Vol 27 (2) ◽  
pp. 202-204
Author(s):  
Myra N. Chávez ◽  
Benedikt Fuchs ◽  
Jörg Nickelsen
Keyword(s):  
Tissue Engineering ◽  
Chlamydomonas Reinhardtii ◽  
Green Alga ◽  
Recombinant Proteins ◽  
Biomedical Devices ◽  
Unicellular Green Alga ◽  
Surgical Sutures ◽  
Novel Strategy ◽  
Clinical Problems

AbstractWe have recently proposed a novel strategy named photosynthetic tissue engineering to overcome clinical problems due to hypoxia. The idea is based on transgenic photoautotrophic microorganisms that produce oxygen and at the same time secrete functional recombinant proteins into tissues. In particular, the unicellular green alga Chlamydomonas reinhardtii has successfully been used to boost the regenerative potential of several biomedical devices, such as dermal scaffolds and surgical sutures.

scholarly journals Schizosaccharomyces pombe ras1 and byr1 are functionally related genes of the ste family that affect starvation-induced transcription of mating-type genes.

1990 ◽  
Vol 10 (2) ◽  
pp. 549-560 ◽  
Author(s):  
S A Nadin-Davis ◽  
A Nasim
Keyword(s):  
Gene Family ◽  
Fission Yeast ◽  
Mating Type ◽  
Growth Cycle ◽  
Yeast Cells ◽  
Null Alleles ◽  
Northern Analysis ◽  
Gene Transcript ◽  
Type Gene

We have further investigated the function of the ras1 and byr1 genes, which were previously shown to be critical for sexual differentiation in fission yeast cells. Several physiological similarities between strains containing null alleles of these genes supports the idea that ras1 and byr1 are functionally closely related. Furthermore, we have found that byr1 is allelic to ste1, one of at least 10 genes which when mutated can cause sterility. Since ras1 had previously been found to be allelic to ste5, both ras and byr genes are now clearly shown to be a part of the ste gene family, thus confirming their close functional relationship. The observation that the mating-type loci could overcome the sporulation block of ras1 and byr1 mutant strains prompted investigation of the role of the ras-byr pathway in the induction of the mating-type gene transcripts upon nitrogen starvation. By Northern analysis of RNA preparations from strains carrying wild-type or mutant ras1 alleles and grown to different stages of the growth cycle, we have shown that ras1 plays an important role in inducing the Pi transcript of the mating-type loci and the mei3 gene transcript. These observations provide a molecular basis for the role of the ste gene family, including ras1 and byr1, in meiosis and indicate that further characterization of other ste genes would be very useful for elucidating the mechanism of ras1 function in fission yeast cells.

scholarly journals The sum1-1 mutation affects silent mating-type gene transcription in Saccharomyces cerevisiae.

1990 ◽  
Vol 10 (1) ◽  
pp. 409-412 ◽  
Author(s):  
G P Livi ◽  
J B Hicks ◽  
A J Klar
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mating Type ◽  
Transcriptional Control ◽  
Gene Mutations ◽  
State Level ◽  
Mating Type Gene ◽  
Gene Transcripts ◽  
Mating Type Genes ◽  
Type Gene ◽  
Type Information

The silent mating-type genes (HML and HMR) of Saccharomyces cerevisiae are kept under negative transcriptional control by the trans-acting products of the four MAR/SIR loci. MAR/SIR gene mutations result in the simultaneous derepression of HML and HMR gene expression. The sum1-1 mutation was previously identified as an extragenic suppressor of mutations in MAR1 (SIR2) and MAR2 (SIR3). As assayed genetically, sum1-1 is capable of restoring repression of silent mating-type information in cells containing mar1 or mar2 null mutations. We show here that the mating-type phenotype associated with sum1-1 results from a dramatic reduction in the steady-state level of HML and HMR gene transcripts. At the same time, the sum1-1 mutation has no significant effect on the level of each of the four MAR/SIR mRNAs.

Homothallic switching of Saccharomyces cerevisiae mating type genes by using a donor containing a large internal deletion

1985 ◽  
Vol 5 (8) ◽  
pp. 2154-2158
Author(s):  
B Weiffenbach ◽  
J E Haber
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Gene Conversion ◽  
Mating Type ◽  
Gene Conversion Event ◽  
Conversion Event ◽  
Base Pair Deletion ◽  
Mating Type Genes ◽  
Type Gene ◽  
Mat Locus ◽  
Donor Locus

Homothallic switching of the mating type genes of Saccharomyces cerevisiae occurs by a gene conversion event, replacing sequences at the expressed MAT locus with a DNA segment copied from one of two unexpressed loci, HML or HMR. The transposed Ya or Y alpha sequences are flanked by homologous regions that are believed to be essential for switching. We examined the transposition of a mating type gene (hmr alpha 1-delta 6) which contains a 150-base-pair deletion spanning the site where the HO endonuclease generates a double-stranded break in MAT that initiates the gene conversion event. Despite the fact that the ends of the cut MAT region no longer share homology with the donor hmr alpha 1-delta 6, switching of MATa or MAT alpha to mat alpha 1-delta 6 was efficient. However, there was a marked increase in the number of aberrant events, especially the formation of haploid-inviable fusions between MAT and the hmr alpha 1-delta 6 donor locus.

Sign in / Sign up

Export Citation Format

Share Document