Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Expression of neurotrophin-4 mRNA during oogenesis in Xenopus laevis.
Ibáñez CF
,
Hallböök F
,
Godeau F
,
Persson H
.
???displayArticle.abstract??? Neurotrophin-4 (NT-4), a recently discovered novel member of the family of neurotrophic factors structurally related to nerve growth factor (NGF), is abundantly expressed in the Xenopus laevis ovary. In this study we have localized NT-4 mRNA expressing cells in the Xenopus ovary by in situ hybridization and have used this technique together with Northern blot analyses to quantify NT-4 mRNA expression during oogenesis in Xenopus. In situ hybridization of sections through the Xenopus ovary using an alpha-[35S]-dATP labeled Xenopus NT-4 mRNA specific probe showed an intense labeling over the cytoplasm of oocytes with a diameter of 50-200 microns corresponding to stage I according to Dumont (1972). Labeling was also seen over the cytoplasm of stages II to IV although with a lower intensity than over stage I oocytes. No labeling was seen over more mature oocytes of stages V and VI. NT-4 mRNA could not be detected in the early embryo from the onset of cleavage division to the neurula stage suggesting that the NT-4 gene is not expressed during Xenopus early embryogenesis. The confinement of NT-4 mRNA in the Xenopus ovary to immature oocytes suggests that NT-4 mRNA expression is strictly regulated during oogenesis and that the NT-4 protein could play a role as a maturation factor for immature oocytes.
Fig. 1. NT-4 mRNA expression in the Xenopus laevis ovary.
Ovary from adult Xenopus laevis was sectioned In a cryostat (14
pm thick sections) and the sections were then hybridized to the
Indicated 53-mer oligonucleotides labeled with J~S-dA TP using
terminal deoxynucleotldyl transferase. (A) Hybridization using a
Xenopus NT-4 mRNA specific probe. (S) Hybridization using a
control chicken BDNF mRNA oligonucleotide of sImilar G+C
content. After hybridization, sections were washed In lxSSC at
55"C followed by exoposure to X-ray film for 10 days, Shown In
the figure are photographs of the developed X-ray films. Note
the intense labeling over many small cells with the NT-4 probe
and the absence of labeling with the control probe, Arrows point
at large (stage VI) oocytes which are not labeled with either of
the two probes. Scale bar, 2 mm.
Fig. 2. Bright-field illumination of emulsion
autoradiographs showing NT-4mRNA expressing
oocytes in the Xenopus ovary. Secrions hybridIzed
to the Xenopus NT-4 mRNA specific lA, B) or control
BDNF(CI rxobe were coated with Kodak NTB3 emul-
SIon, e\posed for 5 \Vee~s, developed and Itghtfy
courHerstamedwith cresylvlofe:. Shownrn the fIgure
are bnght-fleld phoromlcrographs of the developed
sections. Note In (A) rhe Intense NT-4 mRNA labeling
over small size oocytes (stages I and If) and the
absence of labelrng over large size (stages Vand VI)
oocytes. (8) shows a higher magnification of the
boxed-in area In (A). Note the Inrense labeling over
the cytoplasm of the stage II oocytes shown in the
picture. (C) No labeling can be seen uSing the control
chicken BDNF probe. Abbreviations. n. nucleus: fe,
follicle cells, pI, pigmented layer. Scale bar In A. 50 um;in B and C. 15um.
Fig. 3. levels of NT.4 mANA in oocytes at different stages of oogenesis.
Emulsion autoradiographs (shown in Fig. 2) of sections hybridized with the
Xenopus NT-4 mRNA specific probe were used to count the number of
grains over an area unit. The area unit chosen was about one hundredth of
a stage f oocyte. Fifteen area units were analyzed in 10 different oocytes
of the indicated stages. Error bars show +/- S.D.
Fig. 4. Northern blot analysis of NT-4 mRNA expression during
oogenesis in Xenopus laevis. Ovaries from rwo adult Xenopus laevis were dissected our and treated with collagenase to remove folliCle cells and release the oocytes. The oocytes were then sorted into the indicated
groups following the stages described by (Dumont. 19721. Toral ovary and
the released follicle cells were also included In the analysis. Toral cellular
RNA was prepared and 40 mg/well of RNA was electrophoresed In a
formaldehyde-conraining 1% agarose gel. The gel was blotted onto a
nitrocellulose filter and hybridized to a 350bp Hmc II fragment from the 3'
exon of the Xenopus NT-4 gene. The filter was washed at high stringency
and exposed for five days to an X-ray film. Note the marked decrease in the
level of NT-4 mRNA in stage Vand VI oocytes.
