FlyBase Allele Report: Dmel\Myt1[1]

General Information

Symbol

Dmel\Myt1¹

Species

D. melanogaster

Name

FlyBase ID

FBal0191423

Feature type

allele

Associated gene

Dmel\Myt1

Associated Insertion(s)

Carried in Construct

Also Known As

myt1^R6

Key Links

Genomic Maps

JBrowse

Allele class

Mutagen

ethyl methanesulfonate

Nature of the Allele

Allele class

Mutagen

ethyl methanesulfonate

(Jin et al., 2005)

Progenitor genotype

Cytology

Description

Nucleotide substitution: ?514. A single nucleotide deletion (corresponding to amino acid residue 173) is predicted to cause a frameshift alteration in the sequence of the protein, followed by a premature stop codon at nucleotide 689 (amino acid residue 232). This truncates the protein within the kinase domain and also deletes other conserved sequence motifs near the C-terminus of the protein.

(Jin et al., 2005)

Mutations Mapped to the Genome

Curation Data

Type

Location

Additional Notes

References

deletion

3L:5,779,025..5,779,025 [-]

Comment:

Position of mutation on reference sequence inferred by FlyBase curator based on author statement. Mutation is a 1 bp deletion in codon 173 which leads to a frameshift and a 232 aa long protein. GAC CGA becomes ACC GAC. Identical mutation to Myt1².

(Jin et al., 2005)

Variant Molecular Consequences

Associated Sequence Data

DDBJ / EMBL / GenBank

DNA sequence

Protein sequence

UniProtKB/Swiss-Prot

UniProtKB/TrEMBL

Expression Data

Reporter Expression

Additional Information

Statement

Reference

Marker for

Reflects expression of

Reporter construct used in assay

Human Disease Associations

Disease Ontology (DO) Annotations

Models Based on Experimental Evidence ( 0 )

Disease

Evidence

References

Modifiers Based on Experimental Evidence ( 0 )

Disease

Interaction

References

Comments on Models/Modifiers Based on Experimental Evidence ( 0 )

Disease-implicated variant(s)

Phenotypic Data

Phenotypic Class

Phenotype Manifest In

adult midgut

(Willms et al., 2020)

centriole | adult stage | male

(Varadarajan et al., 2016)

chromosome | adult stage | male

(Varadarajan et al., 2016)

cyst cell & nucleus (with Df(3L)64D-F)

(Jin et al., 2005)

embryonic/larval midgut | third instar larval stage

(Willms et al., 2020)

female germline stem cell | somatic clone

(Kao et al., 2015)

fusome | adult stage | male

(Varadarajan et al., 2016)

intestinal stem cell | increased number | somatic clone

(Willms et al., 2020)

macrochaeta & adult head (with Df(3L)64D-F)

(Jin et al., 2005)

macrochaeta & adult thorax (with Df(3L)64D-F)

(Jin et al., 2005)

macrochaeta & eye (with Df(3L)64D-F)

(Jin et al., 2005)

meiotic cell cycle (with Df(3L)64D-F)

(Jin et al., 2005)

meiotic spindle | adult stage | male

(Varadarajan et al., 2016)

mitotic cell cycle & cystoblast (with Df(3L)64D-F)

(Jin et al., 2005)

mitotic cell cycle & cystocyte (with Df(3L)64D-F)

(Jin et al., 2005)

nucleolus | adult stage | male

(Varadarajan et al., 2016)

nucleus | adult stage | somatic clone

(Willms et al., 2020)

primary spermatocyte (with Df(3L)64D-F)

(Jin et al., 2005)

ring canal | adult stage | male

(Varadarajan et al., 2016)

seminal vesicle | adult stage | male (with Df(3L)64D-F)

(Jin et al., 2005)

spermatocyte

(Varadarajan et al., 2016)

Detailed Description

Statement

Reference

Myt1¹ homozygous midguts exhibit increased number of dividing cells in third instar larvae and adults.

Myt1¹ MARCM clones exhibit increased number of dividing cells with punctuated PH3-labeling of nuclei and increased number of cells per clone. Myt1¹ clones exhibit mitotic cells negative for both Delta and Prospero, suggesting, by elimination, that they are either enteroblasts or pre-enterocytes.

Myt1¹ homozygous guts exhibit fewer number of Pdm1-positive cells with large nuclei and Pdm1 staining is most prominent in smaller, progenitor-like cells.

(Willms et al., 2020)

Myt1¹ homozygote mutant BrdU-labelled spermatocytes fixed at stage S5/S6 (late G2) often show fragmented nucleoli even though the chromatin has not undergone condensation, the chromosomes of labelled mutant spermatocyte appear less condensed than in stage-matched controls but the timing of meiotic events is relatively normal. The temporal coordination between nuclear envelope breakdown and chromosome condensation is also normal as is the timing of CycA translocation in the nucleus but unlike in controls, CycA is not detectable in fusomes in stage S6 Myt1¹ mutant spermatocytes.

The morphology of Golgi stacks as well as their numbers in Myt1¹ homozygous S5/S6 spermatocytes is comparable to controls, the Golgi dynamics during meiosis is also unperturbed. However, the fusome integrity is compromised in the premeiotic G2 phase-arrested Myt1¹ mutant spermatocytes: the fusomes and ring canals in these spermatocytes appear disrupted and/or constricted compared to controls.

:Myt1¹ homozygote mutant display highly penetrant centrosomal and meiotic spindle defects (multipolar spindle) in spermatocytes but most of the Myt1¹ early postmeiotic cysts appear relatively normal. The centrioles in Myt1¹ mutants disengage prematurely (4 instead of 2 centrioles are therefore detected in majority of S3-S6 mutants spermatocytes) and appear to be randomly distributed between the daughter cells during anaphase I, resulting in postmeiotic cells with variable numbers of centrioles.

(Varadarajan et al., 2016)

Myt1¹ mutant germline stem cells divide faster than controls, and these GSCS are lost more quickly.

(Kao et al., 2015)

Viable hemizygous Myt1¹ mutants (over Df(3L)64D-F) exhibit bristle defects affecting the dorsal thorax, head, and eye, and are male sterile. Although Myt1¹/Df(3L)64D-F females are fertile, they exhibit variable maternal effect lethal embryonic phenotypes in their progeny. Myt1¹/Df(3L)64D-F mutants exhibit normal numbers of germline stem cells. However, they do exhibit a significant increase in secondary spermatogonial cells, relative to controls. In wild-type controls, cysts containing more than eight cells are never observed, while by contrast, approximately 30% of Myt1¹/Df(3L)64D-F mutant testes contain at least one 16-cell cyst, implying that the secondary spermatogonia can undergo an extra round of mitosis in Myt1¹/Df(3L)64D-F mutants. Approximately 10% of the mutant cysts contain twice the expected numbers of primary spermatocytes or spermatids, a phenotype never seen in controls. In both 64-cell and 128-cell Myt1¹/Df(3L)64D-F mutant spermatid cysts, the nuclei and nebenkern are variable and aberrant-looking, which is never seen in controls. There is a marked increase in the number of cyst cell nuclei in Myt1¹/Df(3L)64D-F mutants, relative to controls. In Myt1¹/Df(3L)64D-F mutants, the seminal vesicle is empty, which in wild-type is where mature sperm translocate to after spermatid differentiation, implying a defect in sperm maturation. Myt1¹/Df(3L)64D-F mutant females display a comparable number of germline stem cells as in wild-type controls. However, in contrast to wild-type, approximately 30% of germline stem cells are mitotic, exhibiting a 20-fold increase in mitotic index compared to wild-type. The mutant cystoblasts and their cystocyte descendants also have a significantly higher mitotic index than normal. Myt1¹/Df(3L)64D-F Myt1¹/Df(3L)64D-F egg chambers exhibit the same number of cells as wild-type (16 cells), indicating that ectopic germline cell divisions do not account for this defect in females. Oocyte and nurse cell differentiation appears normal in Myt1¹/Df(3L)64D-F mutants. Examination of germaria reveals a significant increase in the number of cysts (one- to twofold), relative to controls. Although Myt1¹/Df(3L)64D-F mutant cystoblasts and cystocytes are similar in size to controls, the germline stem cells appear slightly smaller.

(Jin et al., 2005)

External Data

Linkouts

Interactions

Show genetic interaction network for Enhancers & Suppressors

Phenotypic Class

Suppressed by

Statement

Reference

Myt1¹ has increased occurrence of cell division | adult stage phenotype, suppressible | partially by rux^UAS.cTa/Scer\GAL4^esg.PU

(Willms et al., 2020)

Myt1¹ has male sterile | recessive phenotype, suppressible by Wee1^UASp.Venus/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has abnormal meiotic cell cycle | recessive phenotype, suppressible by polo^GD7563/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has male sterile | recessive phenotype, suppressible by rux^UASp.cUa/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

NOT suppressed by

Statement

Reference

Myt1¹ has male sterile | recessive phenotype, non-suppressible by polo^GD7563/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has male sterile | recessive phenotype, non-suppressible by Scer\GAL4^VP16.bam/CycA^KK101548

(Varadarajan et al., 2016)

Phenotype Manifest In

Suppressed by

Statement

Reference

Myt1¹ has adult gut phenotype, suppressible | partially by rux^UAS.cTa/Scer\GAL4^esg.PU

(Willms et al., 2020)

Myt1¹ has centriole | male | adult stage phenotype, suppressible by polo^GD7563/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has centriole | male | adult stage phenotype, suppressible by Wee1^UASp.Venus/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has meiotic spindle | male | adult stage phenotype, suppressible by Wee1^UASp.Venus/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has fusome | male | adult stage phenotype, suppressible by Scer\GAL4^VP16.bam/CycA^KK101548

(Varadarajan et al., 2016)

Myt1¹ has centriole | male | adult stage phenotype, suppressible by Scer\GAL4^VP16.bam/CycA^KK101548

(Varadarajan et al., 2016)

Myt1¹ has meiotic spindle | male | adult stage phenotype, suppressible by Scer\GAL4^VP16.bam/CycA^KK101548

(Varadarajan et al., 2016)

Myt1¹ has fusome | male | adult stage phenotype, suppressible by rux^UASp.cUa/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has centriole | male | adult stage phenotype, suppressible by rux^UASp.cUa/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has meiotic spindle | male | adult stage phenotype, suppressible by rux^UASp.cUa/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

NOT suppressed by

Statement

Reference

Myt1¹ has fusome | male | adult stage phenotype, non-suppressible by polo^GD7563/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has fusome | male | adult stage phenotype, non-suppressible by Wee1^UASp.Venus/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has fusome | male | adult stage phenotype, non-suppressible by CycB^KK101163/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has centriole | male | adult stage phenotype, non-suppressible by CycB^KK101163/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has meiotic spindle | male | adult stage phenotype, non-suppressible by CycB^KK101163/Scer\GAL4^VP16.bam

(Varadarajan et al., 2016)

Myt1¹ has fusome | male | adult stage phenotype, non-suppressible by Scer\GAL4^VP16.topi/CycB^KK101163

(Varadarajan et al., 2016)

Myt1¹ has centriole | male | adult stage phenotype, non-suppressible by Scer\GAL4^VP16.topi/CycB^KK101163

(Varadarajan et al., 2016)

Myt1¹ has meiotic spindle | male | adult stage phenotype, non-suppressible by Scer\GAL4^VP16.topi/CycB^KK101163

(Varadarajan et al., 2016)

Additional Comments

Genetic Interactions

Statement

Reference

Expression of polo^GD7563 under the control of Scer\GAL4^{bam.T:Hsim\VP16} partially suppresses the premature centriole disengagement observed in Myt1¹ homozygote mutant spermatocytes but has no effect on the fusome integrity defects and also does not rescue the male sterility.

Expression of Wee1^{Scer\UAS.P\T.T:Avic\GFP-YFP.Venus} under the control of Scer\GAL4^{bam.T:Hsim\VP16} almost completely rescues the centriole engagement and meiotic spindle abnormalities as well as the male sterility of Myt1¹ homozygous mutant adults but does not restore the fusome defects.

Expression of CycA^KK101548 under the control of Scer\GAL4^{bam.T:Hsim\VP16} in the Myt1¹ homozygote mutant background partially rescues the fusome defects as well as the premature centriole disengagement and multipolar meiotic spindle defects characteristic for Myt1¹ mutants but fails to restore the male sterility.

Expression of rux^{Scer\UAS.P\T.cUa} under the control of Scer\GAL4^{bam.T:Hsim\VP16} in the Myt1¹ homozygote mutant background partially rescues the male sterility as well as the spermatocyte fusome defects and almost fully rescues the premature centriole disengagement and meiotic spindle defects of Myt1¹ mutants.

Expression of CycB^KK101163 under the control of either Scer\GAL4^{bam.T:Hsim\VP16} or Scer\GAL4^{topi.T:Hsim\VP16} does not rescue the spermatocyte fusome, centriole and meiotic spindle defects characteristic for Myt1¹ homozygote mutant males.

(Varadarajan et al., 2016)

Xenogenetic Interactions

Statement

Reference

Complementation and Rescue Data

Rescued by

Myt1¹ is rescued by Myt1^{βTub85D.EGFP}

(Varadarajan et al., 2016)

Partially rescued by

Myt1¹ is partially rescued by Scer\GAL4^VP16.bam/Myt1^UASp.EGFP

(Varadarajan et al., 2016)

Myt1¹ is partially rescued by Scer\GAL4^VP16.topi/Myt1^UASp.EGFP

(Varadarajan et al., 2016)

Comments

Expression of Myt1^{Scer\UAS.T:Avic\GFP-EGFP} under the control of Scer\GAL4^{bam.T:Hsim\VP16} fully rescues the fusome defects in spermatocytes and almost completely restores male fertility of Myt1¹ homozygous adults. Expression under the Scer\GAL4^{topi.T:Hsim\VP16} driver only partially rescues the fusome defects in spermatocytes and also partially restores male fertility of Myt1¹ homozygous adults.

The multipolar meiotic spindle defect frequently observed in spermatocytes of Myt1¹ homozygote mutant males is rescued by combination with Myt1^{βTub85D.T:Avic\GFP-EGFP}.

(Varadarajan et al., 2016)

Cell proliferation defects, including germline cysts and the adult bristle phenotype observed in Myt1¹/Df(3L)64D-F mutants is rescued by addition of Myt1^+t3.6.

(Jin et al., 2005)

Images (0)

Mutant

Wild-type

Stocks (1)

Bloomington

84950

w^*; Myt1¹/TM6B, Tb¹

Notes on Origin

Discoverer

External Crossreferences and Linkouts ( 0 )

Synonyms and Secondary IDs (3)

Reported As

Symbol Synonym

Myt1¹

myt1¹

(Varadarajan et al., 2016, Kao et al., 2015)

myt1^R6

(Willms et al., 2020, Varadarajan et al., 2016)

Name Synonyms

Secondary FlyBase IDs

References (4)

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