vasa is required for GURKEN accumulation in the oocyte, and is involved in oocyte differentiation and germline cyst development

Abstract

The Drosophila gene vasa is required for pole plasm assembly and function, and also for completion of oogenesis. To investigate the role of vasa in oocyte development, we generated a new null mutation of vasa, which deletes the entire coding region. Analysis of vasa-null ovaries revealed that the gene is involved in the growth of germline cysts. In vasa-null ovaries, germaria are atrophied, and contain far fewer developing cysts than do wild-type germaria; a phenotype similar to, but less severe than, that of a null nanos allele. The null mutant also revealed roles for vasa in oocyte differentiation, anterior-posterior egg chamber patterning, and dorsal-ventral follicle patterning, in addition to its better-characterized functions in posterior embryonic patterning and pole cell specification. The anterior-posterior and dorsal-ventral patterning phenotypes resemble those observed in gurken mutants. vasa-null oocytes fail to efficiently accumulate many localized RNAs, such as Bicaudal-D, orb, oskar, and nanos, but still accumulate gurken RNA. However, GRK accumulation in the oocyte is severely reduced in the absence of vasa function, suggesting a function for VASA in activating gurken translation in wild-type ovaries.

Primordial Germ Cell Development in the Poeciliid, Gambusia holbrooki, Reveals Shared Features Between Lecithotrophs and Matrotrophs

“…Inferred from its maternal inheritance and exclusive detection in migrating PGCs, vasa likely underpins PGC formation and function in G. holbrooki . This is consistent across taxa with maternally inherited mode of germline determination ( Styhler et al, 1998 ; Kuznicki et al, 2000 ; Tanaka et al, 2000 ; Hickford et al, 2011 ). Functionally, the DEAD-box domain of VASA proteins underpin regulatory roles which restructure and remodel protein-coding RNAs to facilitate their translation ( Linder, 2006 ; Sengoku et al, 2006 ).…”

Tejas functions as a core component of nuage assembly and precursor processing inDrosophilapiRNA biogenesis

“…All stocks were maintained at 25°C with standard methods. The mutant alleles used in the study were tej 48–5 (Patil and Kai 2010), vas PH165 (Styhler et al 1998), spn-E 616 (Ott, Nguyen, and Navarro 2014), krimp f06583 (BL# 18990) (Lim and Kai 2007), ago3 t2/t3 (BL# 28269; BL# 28270) (Li et al 2009) aub QC42/HN2 (BL# 4968; BL# 8517) (Schüpbach and Wieschaus 1991), nxf3 Δ (BL# 90328) (Kneuss et al 2019), Df(2L)BSC299 (BDSC# 23683), Df(3R)Exel8162 (BL# 7981). Driver lines for germline and somatic gonadal cells were NGT40 -Gal4; nos -Gal4 VP16 (Grieder, De Cuevas, and Spradling 2000), and Traffic jam -Gal4 (DGRC# 104055) (Hayashi et al 2002), respectively.…”

mRNA helicases: the tacticians of translational control

“…It exhibits ATP-dependent RNA helicase activity 103 and associates with eIF5B 104,105 . The VAS-eIF5B interaction has been implicated genetically in the translation of gurken mRNA, which is expressed in the oocyte and is critical for embryonic patterning 106,107 , and mei-P26 mRNA, which regulates micro RNAs (miRNAs) and cell growth in the D. melanogaster ovarian stem cell lineage 98,108 . VAS binds specifically to a U-rich element in the mei-P26 3′ UTR and is believed to activate translation by recruiting eIF5B to the mRNA, which in turn allows the 60S subunit to be recruited and to join the 40S subunit 104,109 (FIG.…”