translational repressor - zinc finger - crucial organizer of the germ plasm - targets Hunchback and Bicoid mRNAs to achieve posterior identity - acts like a clamp to hold Pumilio close to specific RNAs, which allows Pumilio to switch off the production of the corresponding proteins
Gene model reviewed during 5.47
2.4 (northern blot)
None of the polypeptides share 100% sequence identity.
401 (aa); 43 (kD predicted)
Interacts with pum and brat. Acts via the formation of a quaternary complex composed of pum, nos, brat and the 3'-UTR mRNA of hb. Interacts with cup. Binds RNA with no specificity.
The Nanos-type zinc finger is composed of two C2HC motifs, each motif binding one molecule of zinc. The presence of the zinc molecules is essential for the translation repression activity of the protein.
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\nos using the Feature Mapper tool.
As deduced from GFP labeled nos transcripts in early egg chambers nos transcript localizes to the posterior of the oocyte. There is a transient redistribution to an anterior ring at the margin of the oocyte during stages 8 and 9. nos transcript is no longer detected in the oocyte at stage 10. At stage 10b nurse cell dumping is initiated and by stage 11 nos transcript can be detected in the posterior cortex of the oocyte with a punctate distribution. Cooccurence with vas protein suggests that nos transcript associates with the germ plasm. Maximum accumulation of nos transcript is observed at stage 13/14.
in situ hybridization detects a localized nos transcript at the posterior pole in embryos, however, northern blot analysis detects high transcript levels in both anterior and posterior embryo halves, indicating that transcript is expressed uniformly, and subsequently localized to the posterior pole.
During oogenesis, nos transcipt is first clearly detected at stage S5, in both nurse cells and oocytes. At stage S7-8, nos transcript transiently localizes to the anterior margin of the oocyte. At stage S10, a high level of nos transcript is present in oocytes; this transcript subsequently dumped into the oocyte. By stage S12, nos transcript begins to accumulate at the posterior pole of the oocyte, and is localized to the posterior pole of the oocyte at the later stages of oogenesis. In embryos, nos transcript is undetectable after germ band extension.
The 2.4 kb nos transcript is detected at high levels in ovaries and in 0-2 hour embryos, and at much lower levels in 2-8 hour embryos. This transcript is not detected in older embryos, larvae, or pupae. The nos transcript localizes to the posterior pole of stage 1-2 embryos. The levels of nos transcript in pole cells are high at stage 3 and 4, and have declined dramatically by early germ band extension (stage 8), with no pole cell-specific staining detected after stage 10.
Highest levels of nos protein in the germarium are detected in germline cysts in region 2. Levels decline as the cysts are encapsulated by somatic cells. Lower levels of nos protein have previously been observed in the germline stem cells and dividing cystoblasts (FBrf0074750).
During oogenesis, nos protein can be detected strongly in germarium region 1, and weakly in germarium region 2a. Low levels of nos protein can be observed in nurse cell/oocyte clusters at stages S3-6, and high levels in nurse cells at stage S10. nos protein is never observed in oocytes. After pole bud formation in embryos, nos protein is rapidly degraded outside of the pole cells. nos protein is observed in embryonic germline cells as late as embryonic stage 15.
In wild type embryos, nos protein forms a concentration gradient emanating from the posterior pole and extending into the presumptive abdomen. nos protein distribution is indistinguishable in wild type and pum mutant embryos, as assayed by filtered fluorescence-imaging.
GBrowse - Visual display of RNA-Seq signalsView Dmel\nos in GBrowse 2
Please Note FlyBase no longer curates genomic clone accessions so this list may not be complete
Please Note This section lists cDNAs and ESTs that fall within the genomic extent of the gene model, which may include cDNAs and ESTs of genes within introns, or of overlapping genes. Please see GBrowse for alignment of the cDNAs and ESTs to the gene model.
For each fully sequenced cDNA the DGRC maintains various forms of the cDNA (e.g tagged or untagged) in several different host vectors for subsequent cloning and expression in Drosophila and Drosophila cell lines.
Source for merge of: nos l(3)j3B6
smg protein interacts with AGO1 protein, and AGO1 protein interacts with and is required for the translational repression of the smg target, nos mRNA. The AGO1 protein/nos mRNA interaction does not require a miRNA, but does require msg protein.
Regulation of nos protein expression in wild-type germaria depends on sequences in the 3'UTR of the transcript.
nos is not required for the initial elaboration of dendritic branches in class IV da neurons, but is required at later stages of development to maintain dendrite complexity.
nos mRNA localisation is dispensible for normal abdominal patterning in the embryo, providing that nos translation is properly modulated. In contrast, localisation of nos mRNA to the germ plasm, but not translational regulation, is essential for nos function in the developing germ cells.
nos is essential for establishing and maintaining germline stem cells by preventing their precocious entry into oogenesis. nos is required cell autonomously for germline stem cell renewal (though not cyst differentiation). It is likely that nos represses the translation of differentiation factors in primoridal germ cells and germline stem cells. Zygotic nos is required at two distinct phases during pre-oogenic PGC development. The first pase is embryonic to first larval instar. The second phase is from the late third-instar to the pupal stage, that spans germline stenm cell establishment.
nos and pum control the elaboration of high-order dendritic branches of class III and IV, but not class I and II, dendritic arborization neurons. nos and pum require each other to control dendrite morphogenesis, but hb is not required.
Posterior localization of nos RNA initiates immediately upon nurse cell dumping and occurs by diffusion, entrapment and actin-dependent anchoring of RNA entering the oocyte. Long range movement of nos RNA can occur in the absence of oocyte streaming.
The CCHC zinc finger motifs of nos, which coordinate two metal ions, are essential for all known functions of the nos protein. The "tail region" C-terminal to the zinc fingers is required for abdomen formation and germ cell migration, but not for oogenesis.
The joint action of two RNA degradation pathways (a maternally encoded and a zygotic pathway) controls maternal transcript degradation and its timing in the early embryo. nos transcripts (relatively rare in abundance) are degraded almost exclusively by the maternal pathway.
In mutant females, germline stem cells divide only a few times and then degenerate, due to loss of plasma membrane. Following germ cell loss, germaria carry on massive mitochondrial biogenesis activity. In mutant males, spermatogenesis is progressively affected and the males eventually become sterile.
The developmental defects of nos- pole cells can be traced to the blastoderm stage. nos- pole cells, but not nos+ pole cells, are transcriptionally active in the blastoderm. The nos- pole cells also abnormally continue dividing, instead of becoming quiescent. Sxl is an important target for repression by nos in germ cells.
Maternally deposited nos is essential for normal germ cell migration. Lack of zygotic activity of nos and pum has a dramatic effect on germline development of homozygous females. nos and pum act in the germline, affecting germline stem cell development. nos function lies in the differentiation of the stem cell progeny, the cystoblast. nos and pum may interact with different partners in the germline.
In a sample of 79 genes with multiple introns, 33 showed significant heterogeneity in G+C content among introns of the same gene and significant positive correspondence between the intron and the third codon position G+C content within genes. These results are consistent with selection adding against preferred codons at the start of genes.
A Cys-Cys-His-Cys metal-binding domain in nos is essential for translational regulation. Each of two CCHC motifs are essential for nos activity. Each is capable of binding Zn(II) or Co(II) ions. nos binds to RNA with high affinity but cannot alone discriminate between mutant and wild-type NRE RNAs.
A study of the mechanisms of nos-mediated translational repression indicates that nos and pum determine posterior morphology by promoting the deadenylation of maternal hb mRNA, thereby repressing its translation.
The nos protein gradient in embryos is generated by translational regulation acting through the 184bp TCE (Translational Control Element) of the 3' UTR. The TCE is required to prevent the translation of unlocalized nos mRNA.
Cis-acting sequences within the nos 3'UTR, both necessary and sufficient for localisation of RNA to the posterior of the embryo, occupy a 547 nucleotide region and contain sequences that are partially redundant in function.
nos is essential for germline formation, pole cells lacking nos activity fail to migrate into the gonads so do not become functional germ cells. In such pole cells, gene expression begins prematurely during pole cell migration. Premature activation of genes in these germline precursors may mean that these cells fail to develop normally.
Posterior localisation of the nos RNA is mediated by sequences within the 3' untranslated region and requires the function of eight posterior group genes. Unlocalised nos RNA is translationally repressed, this repression is mediated by the 3' untranslated region. Sequences that mediate translational repression overlap but are independent of those required for localisation.
nos response elements (NRE) in the hb mRNA mediate nos repression of hb maternal transcript translation. pum protein is an NRE binding factor, pum recognises the NRE and recruits nos, the resulting complex is thought to inhibit some component of the translation machinery.
Posterior localisation of nos RNA is mediated by sequences within the nos 3' untranslated region (3'UTR) and required the function of eight genes of the posterior group. Unlocalised nos RNA in embryos mutant for any of the posterior genes is stable and the embryos develop abdominal defects characteristic of nos mutants. Unlocalised nos RNA is translationally repressed, repression is mediated by the 3' UTR and can be alleviated by replacement of the UTR with heterologous UTR sequences or posterior localisation.
nos is involved in the directed intercalation of cells during germ band extension.
Comparisons of early development to that in other insects have revealed conservation of some aspects of development, as well as differences that may explain variations in early patterning events.
A screen for suppressors of nos mutations identified alleles of E(z). E(z) is required to maintain the expression domain of kni and gt initiated by the maternal hb gradient. A small region of the kni promoter mediates regulation by E(z) and hb. Imprinting at the chromatin level may underlie the determination of anteroposterior polarity in the early embryo.
pumilio, expressed in the same pattern as nanos, is not required for either the expression of nanos protein or its transport to the presumptive abdomen.
nanos 3' untranslated region is sufficient for nanos RNA localization. In experiments using bicoid sequences to mislocalise nanos, embryos with mirror image symmetry with double abdomens result if nanos is localised at both the anterior and posterior ends. Anteriorly localised nos suppresses translation of maternally supplied hunchback mRNA and thereby alters gap gene expression.
Overexpression of osk leads to higher levels of osk mRNA that is both correctly localised to the posterior pole and unlocalised. Consequently nos is activated ectopically causing extensive shifts in body patterning. Germ cell formation is also affected, this can be enhanced by genetically decreasing nos activity.
nos acts to prevent the expression of hb in the posterior half of the embryo.
Expression from the Ecol\lacZ-Kr730 Kr-promoter fusion construct was monitored in nos- embryos to ensure the target site for nos mediated Kr expression has not been lost.
gt may respond to the posterior morphogen nos in the embryo. nos represses maternal hb expression post-transcriptionally, so the effect of nos on gt expression may be mediated through hb.
nos is critical for pole plasm formation and is required for the synthesis of the posterior signal in the nurse cells. The distribution of the signal to the presumptive posterior pole occurs after egg deposition. BicD,nos embryos suppress all abdominal development: the nos gene is critical for the normal and ectopic presence of the posterior signal.
Mutations in maternal posterior class gene nos do not interact with RpII140wimp.
The degree of regulation mediated by the NREs in maternal hb mRNA depends on the level of nos.
nos mutants exhibit deletion of the abdomen and pole plasm.
Mature follicles are immunologically stained for asymmetric distribution of ecdysteroid-related antigen. During late oogenesis localisation of the antigen changes dramatically suggesting the antigen plays a role in early embryogenesis and, perhaps, in pattern formation.
nos gene function is not required for pole cell formation.
nos plays a role in polar granule formation.
Double anterior structure induction in nos is more efficient by genetic methods, within nos mutant embryos, than removal of posterior cytoplasm.