{{Short description|RNA binding protein}} '''''Vasa''''' is an RNA-binding protein with an ATP-dependent RNA helicase that is a member of the DEAD box family of proteins. The vasa gene is essential for germ cell development and was first identified in ''Drosophila melanogaster'',<ref name=":5" /> but has since been found to be conserved in a variety of vertebrates and invertebrates including humans.<ref name=":1" /><ref name=":2" /> The Vasa protein is found primarily in germ cells in embryos and adults,<ref name=":1" /> where it is involved in germ cell determination and function, as well as in multipotent stem cells, where its exact function is unknown.<ref name=":2" />
== Gene == The Vasa gene is a member of the DEAD box family of RNA helicases in ''Drosophila melanogaster.''<ref name=":5">{{cite journal | vauthors = Raz E | title = The function and regulation of vasa-like genes in germ-cell development | journal = Genome Biology | volume = 1 | issue = 3 | article-number = REVIEWS1017 | date = 2000 | pmid = 11178242 | doi = 10.1186/gb-2000-1-3-reviews1017 | pmc=138859 | doi-access = free }}</ref> Its human ortholog, Ddx4, is located on human chromosome 5q. It is syntenic to mouse chromosome 13, where the mouse vasa gene is located.<ref name=":1">{{cite journal | vauthors = Castrillon DH, Quade BJ, Wang TY, Quigley C, Crum CP | title = The human VASA gene is specifically expressed in the germ cell lineage | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 97 | issue = 17 | pages = 9585–90 | date = August 2000 | pmid = 10920202 | doi = 10.1073/pnas.160274797 | pmc=16908| bibcode = 2000PNAS...97.9585C | doi-access = free }}</ref> The gene is conserved in many invertebrates and vertebrate species such as ''Caenorhabditis elegans'', ''Xenopus'', Zebrafish, flatworms, echinoderms, molluscs, nematodes, mice and rats as an important part of germ line maintenance and function.<ref name=":1" /><ref name=":2" />
All vertebrate species and ''Drosophila'' have only one vasa ortholog. However, ''C. elegans'' has four Vasa genes, of which only one (GLH-1) is essential.<ref>{{cite journal | vauthors = Kuznicki KA, Smith PA, Leung-Chiu WM, Estevez AO, Scott HC, Bennett KL | title = Combinatorial RNA interference indicates GLH-4 can compensate for GLH-1; these two P granule components are critical for fertility in ''C. elegans'' | journal = Development | volume = 127 | issue = 13 | pages = 2907–16 | date = July 2000 | doi = 10.1242/dev.127.13.2907 | pmid = 10851135 }}</ref><ref>{{cite journal | vauthors = Spike C, Meyer N, Racen E, Orsborn A, Kirchner J, Kuznicki K, Yee C, Bennett K, Strome S | title = Genetic analysis of the ''Caenorhabditis elegans'' GLH family of P-granule proteins | journal = Genetics | volume = 178 | issue = 4 | pages = 1973–87 | date = April 2008 | pmid = 18430929 | pmc = 2323790 | doi = 10.1534/genetics.107.083469 }}</ref>
All DEAD box genes, including Vasa, have 9 conserved sequence motifs.<ref name=":0">{{cite journal | vauthors = Linder P | title = Dead-box proteins: a family affair--active and passive players in RNP-remodeling | journal = Nucleic Acids Research | volume = 34 | issue = 15 | pages = 4168–80 | date = 2006 | pmid = 16936318 | pmc = 1616962 | doi = 10.1093/nar/gkl468 }}</ref> The Vasa gene family evolved from a duplication event followed by acquiring certain domains.<ref name=":3">{{cite journal | vauthors = Mochizuki K, Nishimiya-Fujisawa C, Fujisawa T | title = Universal occurrence of the vasa-related genes among metazoans and their germline expression in Hydra | journal = Development Genes and Evolution | volume = 211 | issue = 6 | pages = 299–308 | date = June 2001 | pmid = 11466525 | doi=10.1007/s004270100156| s2cid = 20585574 }}</ref> Early in the evolution of multicellular animals, the duplication of PL10 related DEAD-box gene occurred.<ref name=":4" /> This resulted in animals having both Vasa and PL10 genes, but plants and fungi only have PL10 genes and no Vasa.<ref name=":3" /> After the duplication event, the N-terminal region acquired Zn-knuckle domains which are now conserved in invertebrates. Vertebrates and insects both have lost the Zn-knuckle domains. The number of these domains vary between different species Vasa genes. An important property of Zn-knuckles, which can be categorized as classical zinc fingers,<ref>{{cite journal | vauthors = Gamsjaeger R, Liew CK, Loughlin FE, Crossley M, Mackay JP | title = Sticky fingers: zinc-fingers as protein-recognition motifs | journal = Trends in Biochemical Sciences | volume = 32 | issue = 2 | pages = 63–70 | date = February 2007 | pmid = 17210253 | doi = 10.1016/j.tibs.2006.12.007 }}</ref> is that they are able to bind to single and double stranded DNA or RNA.<ref>{{cite journal | vauthors = Rajavashisth TB, Taylor AK, Andalibi A, Svenson KL, Lusis AJ | title = Identification of a zinc finger protein that binds to the sterol regulatory element | journal = Science | volume = 245 | issue = 4918 | pages = 640–3 | date = August 1989 | pmid = 2562787 | doi=10.1126/science.2562787| bibcode = 1989Sci...245..640R }}</ref> The presence of Zn-knuckles in invertebrates and absence in vertebrates may be an indication of differences in target binding sites. Their presence may be important to functions outside germ line development. An exception to this theory is the presence of Zn-knuckles in all four ''C. elegans'' Vasa genes, which are restricted to functions in the germ line. <ref>{{cite journal | vauthors = Gruidl ME, Smith PA, Kuznicki KA, McCrone JS, Kirchner J, Roussell DL, Strome S, Bennett KL | title = Multiple potential germ-line helicases are components of the germ-line-specific P granules of Caenorhabditis elegans | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 93 | issue = 24 | pages = 13837–42 | date = November 1996 | pmid = 8943022 | doi=10.1073/pnas.93.24.13837 | pmc=19442| bibcode = 1996PNAS...9313837G | doi-access = free }}</ref>
== Protein == The protein product in humans has 724 amino acids, a molecular mass of 79 kDa and 8 conserved domains in all DEAD-box proteins that is involved in RNA helicase activity. Domain V contains the DEAD motif.<ref>{{cite journal | vauthors = Castrillon DH, Quade BJ, Wang TY, Quigley C, Crum CP | title = The human VASA gene is specifically expressed in the germ cell lineage | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 97 | issue = 17 | pages = 9585–90 | date = August 2000 | pmid = 10920202 | doi = 10.1073/pnas.160274797 | pmc=16908| bibcode = 2000PNAS...97.9585C | doi-access = free }}</ref> As with other Vasa related proteins, human Vasa has a N terminus rich in glycine and RGG motif repeats that function in RNA binding.<ref name="pmid9747670">{{cite journal | vauthors = Lüking A, Stahl U, Schmidt U | title = The protein family of RNA helicases | journal = Critical Reviews in Biochemistry and Molecular Biology | volume = 33 | issue = 4 | pages = 259–96 | year = 1998 | pmid = 9747670 | doi = 10.1080/10409239891204233 }}</ref>
Vasa is regulated at the transcript and protein level. Developing embryos and adults regulate Vasa expression to cell and tissue specific locations. In ''Drosophila'', zygotic transcription of Vasa occurs at pole cells, and stays germ-line specific throughout the life of the organism.<ref name="Kitamura 326–337">{{cite journal | vauthors = Kitamura E, Igarashi J, Morohashi A, Hida N, Oinuma T, Nemoto N, Song F, Ghosh S, Held WA, Yoshida-Noro C, Nagase H | title = Analysis of tissue-specific differentially methylated regions (TDMs) in humans | journal = Genomics | volume = 89 | issue = 3 | pages = 326–37 | date = March 2007 | pmid = 17188838 | pmc = 1847344 | doi = 10.1016/j.ygeno.2006.11.006 }}</ref>
The Vasa promoter is regulated through methylation. In cells were Vasa is transcribed successfully, the promoter is hypomethylated and in all other cells it is methylated.<ref name="Kitamura 326–337"/> When Vasa is hypermethylated in testes, spermatogenesis defects may occur.<ref>{{cite journal | vauthors = Sugimoto K, Koh E, Sin HS, Maeda Y, Narimoto K, Izumi K, Kobori Y, Kitamura E, Nagase H, Yoshida A, Namiki M | title = Tissue-specific differentially methylated regions of the human VASA gene are potentially associated with maturation arrest phenotype in the testis | language = En | journal = Journal of Human Genetics | volume = 54 | issue = 8 | pages = 450–6 | date = August 2009 | pmid = 19629140 | doi = 10.1038/jhg.2009.59 | doi-access = free | hdl = 2297/19417 | hdl-access = free }}</ref>
Post-transcriptionally Vasa has several splice forms in different animals.<ref name="Pfister 146–159">{{cite journal | vauthors = Pfister D, De Mulder K, Hartenstein V, Kuales G, Borgonie G, Marx F, Morris J, Ladurner P | title = Flatworm stem cells and the germ line: developmental and evolutionary implications of macvasa expression in ''Macrostomum lignano'' | journal = Developmental Biology | volume = 319 | issue = 1 | pages = 146–59 | date = July 2008 | pmid = 18405892 | doi = 10.1016/j.ydbio.2008.02.045 | doi-access = free }}</ref><ref name="Rebscher 599–611">{{cite journal | vauthors = Rebscher N, Zelada-González F, Banisch TU, Raible F, Arendt D | title = Vasa unveils a common origin of germ cells and of somatic stem cells from the posterior growth zone in the polychaete Platynereis dumerilii | journal = Developmental Biology | volume = 306 | issue = 2 | pages = 599–611 | date = June 2007 | pmid = 17467683 | doi = 10.1016/j.ydbio.2007.03.521 | doi-access = }}</ref> In ''Parhyale hawaiensis'', Vasa transcript is uniformly distributed in the embryo and is localized depending on the stabilization of the 3'UTR (Untranslated Region) to the germ line cells.<ref name="Ozhan-Kizil 230–239">{{cite journal | vauthors = Ozhan-Kizil G, Havemann J, Gerberding M | title = Germ cells in the crustacean ''Parhyale hawaiensis'' depend on Vasa protein for their maintenance but not for their formation | journal = Developmental Biology | volume = 327 | issue = 1 | pages = 230–9 | date = March 2009 | pmid = 19013453 | doi = 10.1016/j.ydbio.2008.10.028 | doi-access = }}</ref> Translation can be inhibited by cis regulatory elements in the transcript's 5' and 3' UTRs. They may inhibit translation by forming secondary RNA structures or binding trans-acting factors. Vasa expression localization is directed by repressing these translation inhibitory pathways.<ref>{{cite journal | vauthors = Chatterjee S, Pal JK | title = Role of 5'- and 3'-untranslated regions of mRNAs in human diseases | journal = Biology of the Cell | volume = 101 | issue = 5 | pages = 251–62 | date = May 2009 | pmid = 19275763 | doi = 10.1042/BC20080104 | doi-access = }}</ref>
Post-translationally, in ''Drosophila'', Vasa protein is localized to the pole plasm during embryonic development. Many other proteins in ''Drosophila'' are also localized to the poles. For example, oskar protein was found to localize to pole plasm and may be involved in anchoring Vasa to polar granules in the posterior pole of the oocyte.<ref>{{cite journal | vauthors = Breitwieser W, Markussen FH, Horstmann H, Ephrussi A | title = Oskar protein interaction with Vasa represents an essential step in polar granule assembly | journal = Genes & Development | volume = 10 | issue = 17 | pages = 2179–88 | date = September 1996 | pmid = 8804312 | doi=10.1101/gad.10.17.2179| doi-access = free }}</ref> Another enzyme, fat facets, may further stabilize Vasa in the pole plasm.<ref>{{cite journal | vauthors = Liu N, Dansereau DA, Lasko P | title = Fat facets interacts with vasa in the Drosophila pole plasm and protects it from degradation | journal = Current Biology | volume = 13 | issue = 21 | pages = 1905–9 | date = October 2003 | pmid = 14588248 | doi=10.1016/j.cub.2003.10.026| doi-access = free | bibcode = 2003CBio...13.1905L }}</ref> Other post-translational modification includes phosphorylation of the Vasa ortholog in ''C. elegans'',<ref>{{cite journal | vauthors = Orsborn AM, Li W, McEwen TJ, Mizuno T, Kuzmin E, Matsumoto K, Bennett KL | title = GLH-1, the ''C. elegans'' P granule protein, is controlled by the JNK KGB-1 and by the COP9 subunit CSN-5 | journal = Development | volume = 134 | issue = 18 | pages = 3383–92 | date = September 2007 | pmid = 17699606 | doi = 10.1242/dev.005181 | doi-access = }}</ref> and arginine methylation in a conserved region of mice, ''Xenopus'' and ''Drosophila'' Vasa genes. <ref>{{cite journal | vauthors = Kirino Y, Vourekas A, Kim N, de Lima Alves F, Rappsilber J, Klein PS, Jongens TA, Mourelatos Z | title = Arginine methylation of vasa protein is conserved across phyla | journal = The Journal of Biological Chemistry | volume = 285 | issue = 11 | pages = 8148–54 | date = March 2010 | pmid = 20080973 | pmc = 2832966 | doi = 10.1074/jbc.M109.089821 | doi-access = free }}</ref>
== Function == One of main function of Vasa protein is in germ cell determination and function.<ref name=":1" /> It uses ATP-dependent RNA helicase catalytic activity to regulate the translation of multiple mRNAs.<ref>{{cite journal | vauthors = Carrera P, Johnstone O, Nakamura A, Casanova J, Jäckle H, Lasko P | title = VASA mediates translation through interaction with a Drosophila yIF2 homolog | journal = Molecular Cell | volume = 5 | issue = 1 | pages = 181–7 | date = January 2000 | pmid = 10678180 | doi=10.1016/s1097-2765(00)80414-1| hdl = 11858/00-001M-0000-0012-F80E-6 | hdl-access = free }}</ref> Vasa unwinds the duplex RNA by binding and bending short stretches of the duplex in a non-processive manner.<ref>{{cite journal | vauthors = Sengoku T, Nureki O, Nakamura A, Kobayashi S, Yokoyama S | title = Structural basis for RNA unwinding by the DEAD-box protein Drosophila Vasa | journal = Cell | volume = 125 | issue = 2 | pages = 287–300 | date = April 2006 | pmid = 16630817 | doi = 10.1016/j.cell.2006.01.054 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Linder P, Lasko P | title = Bent out of shape: RNA unwinding by the DEAD-box helicase Vasa | journal = Cell | volume = 125 | issue = 2 | pages = 219–21 | date = April 2006 | pmid = 16630807 | doi = 10.1016/j.cell.2006.03.030 | doi-access = free }}</ref> The conserved domain may act as chaperones by unwinding RNA secondary structures and refolding properly.<ref>{{cite journal | vauthors = Lorsch JR | title = RNA chaperones exist and DEAD box proteins get a life | journal = Cell | volume = 109 | issue = 7 | pages = 797–800 | date = June 2002 | pmid = 12110176 | doi=10.1016/s0092-8674(02)00804-8| doi-access = free }}</ref> pre-mRNA splicing, ribosome biogenesis, nuclear export, translational regulation and degradation.<ref name=":0" />
Vasa was found to bind RNA in a sequence-specific manner. In the ''Drosophila'' embryos, Vasa binds the Uracil-rich motif of the mei-P26 UTR. A mutation in Vasa reduced the interaction of between Mei-P26 and initiation factor elF58 which in turn significantly reduced translation of the gene.<ref>{{cite journal | vauthors = Liu N, Han H, Lasko P | title = Vasa promotes Drosophila germline stem cell differentiation by activating mei-P26 translation by directly interacting with a (U)-rich motif in its 3' UTR | journal = Genes & Development | volume = 23 | issue = 23 | pages = 2742–52 | date = December 2009 | pmid = 19952109 | pmc = 2788330 | doi = 10.1101/gad.1820709 }}</ref>
Recent evidence in invertebrates suggests that Vasa has a role in multipotent stem cells, but the exact function is unknown.<ref name=":2">{{cite journal | vauthors = Gustafson EA, Wessel GM | title = Vasa genes: emerging roles in the germ line and in multipotent cells | journal = BioEssays | volume = 32 | issue = 7 | pages = 626–37 | date = July 2010 | pmid = 20586054 | pmc = 3090673 | doi = 10.1002/bies.201000001 }}</ref>
=== Mutations ===
==== ''Drosophila'' ====
A null mutation causes female sterility due to severe defects in oogenesis<ref>{{cite journal | vauthors = Styhler S, Nakamura A, Swan A, Suter B, Lasko P | title = vasa is required for GURKEN accumulation in the oocyte, and is involved in oocyte differentiation and germline cyst development | journal = Development | volume = 125 | issue = 9 | pages = 1569–78 | date = May 1998 | doi = 10.1242/dev.125.9.1569 | pmid = 9521895 | url = https://scholar.uwindsor.ca/biologypub/1164 | url-access = subscription }}</ref> but males are fertile.
Homozygous mutations for partial loss of function allows eggs to be fertilized but embryos lack germ cells.<ref name=":4">{{cite journal | vauthors = Schüpbach T, Wieschaus E | title = Maternal-effect mutations altering the anterior-posterior pattern of the Drosophila embryo | language = en | journal = Roux's Archives of Developmental Biology | volume = 195 | issue = 5 | pages = 302–317 | date = July 1986 | pmid = 28306055 | doi = 10.1007/bf00376063 | s2cid = 274353 }}</ref>
==== ''Mus musculus'' ====
Mutations in Vasa homolog, ''Mvh'', cause defects in spermatogenesis but females are fertile. Male sterility may be due to deficiencies in germ cell proliferation and differentiation (the mouse homolog of Droso.). Female fertility may be due to functional redundancy by other DEAD-box family members. Null mutation still allows primordial germ cells to form but have severe defects.<ref>{{cite journal | vauthors = Tanaka SS, Toyooka Y, Akasu R, Katoh-Fukui Y, Nakahara Y, Suzuki R, Yokoyama M, Noce T | title = The mouse homolog of Drosophila Vasa is required for the development of male germ cells | journal = Genes & Development | volume = 14 | issue = 7 | pages = 841–53 | date = April 2000 | doi = 10.1101/gad.14.7.841 | pmid = 10766740 | pmc=316497}}</ref>
==== ''Homo sapiens'' ====
Although there are no studies done on Vasa mutations in humans, it is likely that it would cause sterility.<ref name=":1" />
These sex-specific phenotypes in mice and ''Drosophila'' mutants suggest that Vasa either regulated differently or has different target functions in the two germ line types.<ref name=":2" />
== Tissue, and subcellular distribution == Vasa expression is restricted to tissue specific cells. Until recently it was thought that Vasa protein can only be found in gametes and is undetectable in somatic cells.<ref name=":1" /> Within germ cells, Vasa is expressed in the cytoplasm. During embryogenesis, Vasa is expressed in migratory primordial germ cells (PGCs) at the gonadal ridge in both males and females. This specificity allows Vasa to be used as a highly specific marker for germ cells.<ref name=":1" /> In a patient with Sertoli cell syndrome, no Vasa signal was detected from testicular biopsy.<ref name=":1" /> However, recent studies show that Vasa functions in other cells as well.<ref name=":2" />
A study on ''Macrostomum lignano'' found Vasa expression in multipotent neoblast stem cells in addition to germ cells.<ref name="Pfister 146–159"/> However, RNAi knockdown revealed that either Vasa is non-essential in this organism or is made functionally redundant by other Vasa-like genes. Similar results were found on studies of the colonial ascidian ''Botryllus primigenus'',<ref>{{cite journal | vauthors = Mukai H, Watanabe H | title = Studies on the formation of germ cells in a compound ascidian Botryllus primigenus Oka | journal = Journal of Morphology | volume = 148 | issue = 3 | pages = 377–62 | date = March 1976 | pmid = 943552 | doi=10.1002/jmor.1051480306| s2cid = 46420722 }}</ref> oysters,<ref>{{cite journal | vauthors = Fabioux C, Corporeau C, Quillien V, Favrel P, Huvet A | title = In vivo RNA interference in oyster--vasa silencing inhibits germ cell development | journal = The FEBS Journal | volume = 276 | issue = 9 | pages = 2566–73 | date = May 2009 | pmid = 19476495 | doi = 10.1111/j.1742-4658.2009.06982.x | url = https://archimer.ifremer.fr/doc/00000/6641/ | doi-access = free }}</ref> teleosts,<ref>{{cite journal | vauthors = Miyake A, Saito T, Kashiwagi N, Ando D, Yamamoto A, Suzuki T, Nakatsuji N, Nakatsuji T | title = Cloning and pattern of expression of the shiro-uo vasa gene during embryogenesis and its roles in PGC development | journal = The International Journal of Developmental Biology | volume = 50 | issue = 7 | pages = 619–25 | date = 2006 | pmid = 16892175 | doi = 10.1387/ijdb.062172am | doi-access = free }}</ref> ''clawed frog'',<ref>{{cite journal | vauthors = Ikenishi K, Tanaka TS | title = Involvement of the protein of Xenopus vasa homolog (Xenopus vasa-like gene 1, XVLG1) in the differentiation of primordial germ cells | journal = Development, Growth & Differentiation | volume = 39 | issue = 5 | pages = 625–33 | date = October 1997 | pmid = 9338598 | doi=10.1046/j.1440-169x.1997.t01-4-00010.x| s2cid = 20046434 }}</ref> the parasitic wasp,<ref>{{cite journal | vauthors = Zhurov V, Terzin T, Grbić M | title = Early blastomere determines embryo proliferation and caste fate in a polyembryonic wasp | journal = Nature | volume = 432 | issue = 7018 | pages = 764–9 | date = December 2004 | pmid = 15592416 | doi = 10.1038/nature03171 | bibcode = 2004Natur.432..764Z | s2cid = 4341264 }}</ref> and the crustacean ''Parhyale hawaiensis''.<ref name="Ozhan-Kizil 230–239"/>
Vasa expression has been observed in epithelial ovarian cancer cells. It was found to deter the DNA damage-induced G2 checkpoint by downregulating the expression of another gene.<ref>{{cite journal | vauthors = Hashimoto H, Sudo T, Mikami Y, Otani M, Takano M, Tsuda H, Itamochi H, Katabuchi H, Ito M, Nishimura R | title = Germ cell specific protein VASA is over-expressed in epithelial ovarian cancer and disrupts DNA damage-induced G2 checkpoint | journal = Gynecologic Oncology | volume = 111 | issue = 2 | pages = 312–9 | date = November 2008 | pmid = 18805576 | doi = 10.1016/j.ygyno.2008.08.014 }}</ref> Vasa is also present in chicken embryonic stem cells where it induces expression of germ line genes. This function still supports the most important role of Vasa in germ line development.<ref>{{cite journal | vauthors = Lavial F, Acloque H, Bachelard E, Nieto MA, Samarut J, Pain B | title = Ectopic expression of Cvh (Chicken Vasa homologue) mediates the reprogramming of chicken embryonic stem cells to a germ cell fate | journal = Developmental Biology | volume = 330 | issue = 1 | pages = 73–82 | date = June 2009 | pmid = 19324033 | doi = 10.1016/j.ydbio.2009.03.012 | doi-access = }}</ref> In Cnidarians, Vasa has a role in nerve cells and gland cells.<ref>{{cite journal|last1=Bosch|first1=Thomas C. G.|last2=David|first2=Charles N. | name-list-style = vanc | date = May 1987 | title=Stem cells of Hydra magnipapillata can differentiate into somatic cells and germ line cells|journal=Developmental Biology|volume=121|issue=1|pages=182–191|doi=10.1016/0012-1606(87)90151-5|url=https://epub.ub.uni-muenchen.de/3361/1/019.pdf}}</ref> Other examples include Vasa in multipotent stem cell cluster of ''Polyascus polygenea'' buds and stolon,<ref>{{cite journal | vauthors = Shukalyuk AI, Golovnina KA, Baiborodin SI, Gunbin KV, Blinov AG, Isaeva VV | title = vasa-related genes and their expression in stem cells of colonial parasitic rhizocephalan barnacle Polyascus polygenea (Arthropoda: Crustacea: Cirripedia: Rhizocephala) | journal = Cell Biology International | volume = 31 | issue = 2 | pages = 97–108 | date = February 2007 | pmid = 17085060 | doi = 10.1016/j.cellbi.2006.09.012 | s2cid = 33510591 }}</ref> Vasa in auxiliary cells of oyster ovaries,<ref>{{cite journal | vauthors = Fabioux C, Pouvreau S, Le Roux F, Huvet A | title = The oyster vasa-like gene: a specific marker of the germline in Crassostrea gigas | journal = Biochemical and Biophysical Research Communications | volume = 315 | issue = 4 | pages = 897–904 | date = March 2004 | pmid = 14985097 | doi = 10.1016/j.bbrc.2004.01.145 | url = https://archimer.ifremer.fr/doc/00000/646/ }}</ref> Vasa in non-germ-line lineages in the snail ''Ilyanassa'',<ref>{{cite journal | vauthors = Swartz SZ, Chan XY, Lambert JD | title = Localization of Vasa mRNA during early cleavage of the snail Ilyanassa | journal = Development Genes and Evolution | volume = 218 | issue = 2 | pages = 107–13 | date = February 2008 | pmid = 18214533 | doi = 10.1007/s00427-008-0203-6 | s2cid = 9580109 }}</ref> Vasa in progenitor mesodermal posterior growth zone of the polychaete annelid ''Platynereis dumerilii'',<ref name="Rebscher 599–611"/> and Vasa present in non-genetical segments during Oligochaete development.<ref>{{cite journal | vauthors = Oyama A, Shimizu T | title = Transient occurrence of vasa-expressing cells in nongenital segments during embryonic development in the oligochaete annelid Tubifex tubifex | journal = Development Genes and Evolution | volume = 217 | issue = 10 | pages = 675–90 | date = October 2007 | pmid = 17851685 | doi = 10.1007/s00427-007-0180-1 | hdl = 2115/30348 | s2cid = 19507358 | hdl-access = free }}</ref> But no reports of vasa expressed outside of germ line cells in vertebrates or insects.<ref name=":2" />
==Expression== In ''Drosophila'', ''vasa'' expression is seen in germ cells, specifically the germline stem cells (GSC's) of female ovaries and in the early stages of spermatogenesis in the male testis.
===Staining=== Due to the localization of ''vasa'', immunohistochemistry staining can be done with vasa antibodies. For example, ''vasa'' antibody staining is specific for germ cells in the ''D. melanogaster'' germarium.
This protein is localized to the cytoplasm of fetal germ cells and to the cytoplasm of developing oocytes in mammals.
== References == {{Reflist}}
Category:Developmental genes and proteins Category:Genes