Expression stability of two housekeeping genes (18S rRNA and G3PDH) during in vitro maturation of follicular oocytes in buffalo (Bubalus bubalis)

Using RT-PCR and glutathione level to study the effect of follicular fluid on in vitro maturation and gene expression of sheep oocytes

The aim of this study is to evaluate the effect of sheep follicular fluid (SFF) supplementation of the in vitro maturation (IVM) media of sheep oocytes on the resumption of meiosis, glutathione (GSH) level, and expression of apoptosis (Bax, Bcl-2) as well as heat shock protein beta-1 (HSPB1) genes. Sheep ovaries were collected from the central slaughterhouse of Riyadh city, KSA. Oocytes were aspirated from 3 to 8 mm follicles. Sheep oocytes were cultured in maturation medium with different concentrations of sheep follicular fluid: 0% (control), 10%, 20% and 40% for 24 h. The results indicated that the maturation rate of oocytes was significantly (p ≤ .05) decreased in 40% SFF (36.87%) versus the control (61.3%), 10% SFF (63.95%) and 20% SFF (64.08%). The supplementation of the IVM medium with 10% SFF induced an intra-oocyte GSH concentration that was significantly higher than in sheep oocytes cultured with 20% and 40% SFF and similar to the GSH content in oocytes cultured without SFF. Real-time polymerase chain reaction analysis of gene expression revealed no significant differences in the Bax and HSPB1 genes between the control and 10% SFF, whereas they were significantly higher in 40% FF (p ≤ .05) compared to the control. The expression of Bax:Bcl-2 was significantly higher in 20% and 40% SFF compared to the control group. In conclusion, the addition of SFF to the IVM culture of sheep oocytes is recommended to support nuclear maturation and increase oocyte competence.

Expression analysis of Cdx2 and Pou5f1 in a marsupial, the stripe-faced dunnart, during early development

The first lineage allocation during mouse development forms the trophectoderm and inner cell mass, in which Cdx2 and Pou5f1 display reciprocal expression. Yet Cdx2 is not required for trophectoderm specification in other mammals, such as the human, cow, pig, or in two marsupials, the tammar and opossum. The role of Cdx2 and Pou5f1 in the first lineage allocation of Sminthopsis macroura, the stripe-faced dunnart, is unknown. In this study, expression of Cdx2 and Pou5f1 during oogenesis, development from cleavage to blastocyst stages, and in the allocation of the first three lineages was analyzed for this dunnart. Cdx2 mRNA was present in late antral-stage oocytes, but not present again until Day 5.5. Pou5f1 mRNA was present from primary follicles to zygotes, and then expression resumed starting at the early unilaminar blastocyst stage. All cleavage stages and the pluriblast and trophoblast cells co-expressed CDX2 and POU5F1 proteins, which persisted until early stages of hypoblast formation. Hypoblast cells also show co-localisation of POU5F1 and CDX2 once they were allocated, and this persisted during their division and migration. Our studies suggest that CDX2, and possibly POU5F1, are maternal proteins, and that the first lineage to differentiate is the trophoblast, which differentiates to trophectoderm after shell loss one day before implantation. In the stripe-faced dunnart, cleavage cells, as well as trophoblast and pluriblast cells, are polarized, suggesting the continued presence of CDX2 in both lineages until late blastocyst stages may play a role in the formation and maintenance of polarity.

Identification of stable reference genes for gene expression studies using quantitative real time PCR in buffalo oocytes and embryos

The present study was aimed to validate expression stability of 6 housekeeping genes (viz. YWHAZ, SDHA, GAPDH, RPS15, RPS18 and RN18S1) in the oocytes and embryos of different stages in buffalo. A modified Trizol protocol was optimized for RNA isolation from as few as five oocytes. The expression level of selected genes was studied by an optimized real time PCR using DCT method and their stability of expression was evaluated by Microsoft Excel based visual application, geNORM. The analysis revealed that the RPS15 and GAPDH were the most stable genes across different samples. Also, the geometric mean of three genes (i.e. RPS15,RPS18 and GAPDH) were found suitable for normalization of real time PCR data from buffalo oocytes⁄embryos. The information would help in more accurate interpretation of gene expression data from oocytes⁄embryos towards understanding the molecular events in these cells during development.

The effect of hypothermia on the expression of TIMP-3 after traumatic brain injury in rats

Here we investigate the effect of hypothermia on the expression of apoptosis-regulating protein TIMP-3 after fluid percussion traumatic brain injury (TBI) in rats. We began with 210 adult male Sprague-Dawley rats and randomly assigned them to three groups: TBI with hypothermia treatment (32°C), TBI with normothermia (37°C), and sham-injured controls. TBI was induced by a fluid percussion TBI device. Mild hypothermia (32°C) was achieved by partial immersion in a water bath (0°C) under general anesthesia for 4 h. The rats were killed at 4, 6, 12, 24, 48, and 72 h and 1 week after TBI. The mRNA and protein level of TIMP-3 in both the injured and uninjured hemispheres of the brains from each group were measured using RT-PCR and Western blotting. In the normothermic group, TIMP-3 levels in both the injured and uninjured hemispheres were significantly increased after TBI compared with those of sham-injured animals (p < 0.01). In contrast, post-traumatic hypothermia significantly attenuated this increase. According to the RT-PCR and Western blot analyses, the maximum mRNA levels of TIMP-3 were reduced to 60.60 ± 2.30%, 55.83 ± 1.80%, 66.03 ± 2.10%, and 64.51 ± 1.50%, respectively, of the corresponding values in the normothermic group in the injured and uninjured hemispheres (cortex and hippocampus) of the hypothermia group (p < 0.01), while the respective maximum protein levels of TIMP-3 were reduced to 57.50 ± 1.50, 52.67 ± 2.20, 60.31 ± 2.50 and 54.76 ± 1.40 (p < 0.01). Our data suggest that moderate fluid percussion brain injury significantly upregulates TIMP-3 expression, and that this increase may be suppressed by hypothermia treatment.

A novel marsupial pri-miRNA transcript has a putative role in gamete maintenance and defines a vertebrate miRNA cluster paralogous to the miR-15a/miR-16-1 cluster

Successful maintenance, survival and maturation of gametes rely on bidirectional communication between the gamete and its supporting cells. Before puberty, factors from the gamete and its supporting cells are necessary for spermatogonial stem cell and primordial follicle oocyte maintenance. Following gametogenesis, gametes rely on factors and nutrients secreted by cells of the reproductive tracts, the epididymis and/or oviduct, to complete maturation. Despite extensive studies on female and male reproduction, many of the molecular mechanisms of germ cell maintenance remain relatively unknown, particularly in marsupial species. We present the first study and characterisation of a novel primary miRNA transcript, pri-miR-16c, in the marsupial, the stripe-faced dunnart. Bioinformatic analysis showed that its predicted processed miRNA – miR-16c – is present in a wide range of vertebrates, but not eutherians. In situ hybridisation revealed dunnart pri-miR-16c expression in day 4 (primordial germ cells) and day 7 (oogonia) pouch young, in primary oocytes and follicle cells of primordial follicles but then only in follicle cells of primary, secondary and antral follicles in adult ovaries. In the adult testis, pri-miR-16c transcripts were present in the cytoplasm of spermatogonial cells. The oviduct and the epididymis both showed expression, but not any other somatic tissues examined or conceptuses during early embryonic development. This pattern of expression suggests that pri-miR-16c function may be associated with gamete maintenance, possibly through mechanisms involving RNA transfer, until the zygote enters the uterus at the pronuclear stage.

Cloning and characterization of a new gene from the PAT protein family, in a marsupial, the stripe-faced dunnart (Sminthopsis macroura)

Recent studies of PAT proteins in Drosophila and Xenopus have revealed significant roles for this family of proteins in the polarized transport of lipid droplets and maternal determinants during early embryogenesis. In mammals, PAT proteins are known to function mainly in lipid metabolism, yet research has yet to establish a role for PAT proteins in mammalian embryogenesis. Oocytes and early cleavage stages in Sminthopsis macroura show obvious polarized cytoplasmic distribution of organelles, somewhat similar to Drosophila and Xenopus, suggesting that a PAT protein may also be involved in S. macroura embryonic development. In the present study, we identified a new marsupial gene for PAT family proteins, DPAT, from S. macroura. Expression analyses by RT-PCR and whole mount fluorescent in situ hybridization revealed that DPAT expression was specific to oocytes and cleavage stage conceptuses. Analysis of the localization of lipid droplets during S. macroura early embryonic development found a polarized distribution of lipid droplets at the two- and four-cell stage, and an asymmetric enrichment in blastomeres on one side of conceptuses from two- to eight-cell stage. Lipid droplets largely segregate to pluriblast cells at the 16-cell stage, suggesting a role in pluriblast lineage allocation.