Studies on the maintenance of porcine graafian follicles in organ culture

Quantitative bioluminescence imaging of transgene expression in intact porcine antral follicles in vitro

BACKGROUND

The porcine oocyte maturation in vivo occurs within the ovarian follicle and is regulated by the interactions between oocytes and surrounding follicular components, including theca, granulosa, and cumulus cells, and follicular fluid. Therefore, the antral follicle is an essential microenvironment for efficient oocyte maturation and its developmental competence. Quantitative bioluminescence imaging of firefly luciferase reporter genes in an intact antral follicle would allow investigation of changes in cellular and molecular events and in the context of the whole follicles. In this study, we investigate factors influencing bioluminescence measurements as a first step towards developing a new bioluminescence imaging system for intact antral follicles.

METHODS

We analyzed the time course of bioluminescence emitted from transfected living intact follicles using a cationic lipid mediated gene transfer method with increasing doses (1-3 μg) of firefly luciferase reporter gene (pGL4). In addition, a standard luciferase assay was used to confirm the luciferase expression in granulosa cells in the transfected intact antral follicles. Finally, the dose effects of substrate, D-luciferin, were determined for optimal quantitative bioluminescence imaging of intact porcine antral follicles in vitro.

RESULTS

The level of luciferase activity of follicles with 3 μg pGL4 was significantly (P < 0.05) greater than the 1 μg and 2 μg groups at 1 min after D-luciferin injection. The bioluminescence intensity of transfected follicles reached a peak at 1 min, and then it was significantly (P < 0.05) reduced within 2 min after injection of D-luciferin; with the level of bioluminescence emission remained constant from 2.5 to 10 min. The bioluminescence emission was maximal with 300 μg of D-luciferin.

CONCLUSIONS

The results of this study suggested that the investigation of factors influencing bioluminescence measurements is a critical step toward developing a new bioluminescence imaging model. This study is the first to demonstrate that reporter genes can be transferred to intact granulosa cells with a lipid-mediated gene transfer method within intact follicles in vitro, and the level of transgene expression can be assessed by bioluminescence imaging in living intact antral follicles.

The biology and technology of follicular oocyte development in vitro

Fully mature oocytes are the rarest cells in the body. A premenopausal woman produces only one during each menstrual cycle and that survives for just a single day. Ovarian productivity is parsimonious in order that the ovulation rate matches the optimal capacity of the uterus for carrying conceptuses to full-term. But, in this new era of assisted reproductive medicine, there are many applications for which spare oocytes are needed (Table 1), and it is desirable to obtain more cells than are routinely available during superstimulated cycles. Since the great majority of ovarian oocytes undergo atresia (> 99.9%), the possibility of tapping the store of immature oocytes before they degenerate and maturing them in vitro is very attractive.

Multipolymer reaction system for selective aerobic alcohol oxidation: simultaneous use of multiple different polymer-supported ligands

A multipolymer reaction system has been developed in which a water-soluble polymer-supported 2,2'-bipyridine group and a similarly immobilized TEMPO derivative are used as ligands for copper to effect the mild and selective aerobic oxidation of primary alcohols in acetonitrile-water solvent. In this reaction system, poly(ethylene glycol) monomethyl ether (molecular weight = 5000 Da) was used as the support for both the 2,2'-bipyridine and TEMPO moieties because of its solubility properties. The use of these functionalized polymers simultaneously in catalytic quantities allows for primary alcohols to be oxidized selectively to the corresponding aldehydes in an environmentally friendly manner. This is the first reported example of using two different polymer-supported ligands together to form an organometallic species capable of catalyzing an organic reaction.

Multipolymer solution-phase reactions: application to the Mitsunobu reaction

The realization of the first polymer-on-polymer Mitsunobu reaction, in which a polymeric phosphine is used simultaneously with a polymeric azodicarboxylate, is reported. This strategy employs the use of soluble oligomers generated from ring-opening methathesis polymerization. 31P NMR analysis revealed that the two polymers were interacting to generate the Mitsunobu products. Application to several substrates, as well as comparison experiments with other polymeric reagents, is described.

Dendritic aliphatic polyethers as high-loading soluble supports for carbonyl compounds and parallel membrane separation techniques

This paper describes the use of dendritic polyglycerol as a new high-loading polymeric support. The soluble polyether skeleton allows the parallel synthesis of small libraries on a large scale (1-5 mmol). Purification of polymer-bound products is easily achieved by a parallel dialysis apparatus, which was developed to separate up to 12 reaction mixtures simultaneously. The terminal 1,2-diol groups of polyglycerol (loading capacity: 4.1 mmol diol/g) can be directly coupled with carbonyl compounds without additional linker groups. At the same time the polyglycerol support acts as a polymeric ketal protecting group. The coupling of the carbonyl compounds occurs in high yields, and effective loading capacities of up to 3.5 mmol of ketone/g can be reached. The obtained polymeric acetals can easily be characterized by standard analytical techniques, such as NMR, IR, UV, and SEC. The versatility of this new polymeric support for solution-phase organic synthesis is demonstrated by two efficient polymer-supported syntheses: nucleophilic substitutions of gamma-chloroketones with amines and Suzuki-coupling on p-bromobenzaldehyde. The acid-catalyzed acetal cleavage with a solid-phase acidic ion-exchange resin in methanol demonstrates the orthogonal use of these soluble polymeric supports with conventional solid-phase reagents. Cleavage of products occurs in high yields, and almost complete recovery (>95%) of the polyglycerol support has been demonstrated after phase separation or ultrafiltration.

Soluble polymer bound cleavage reagents: a multipolymer strategy for the cleavage of tertiary amines from REM resin

Soluble polymer bound reagent 1 has been prepared to cleave tertiary amines from REM resin. Normally, amines cleaved from REM resin require extraction or chromatography to remove excess cleavage reagent and its byproducts. The solubility profile of non-crosslinked polystyrene (NCPS) based reagent 1 eliminates the need for such purification and allows for the direct isolation of a library of pure tertiary amines through simple filtration and concentration operations.

Effects of gonadotropins on oocyte maturation and progesterone production by porcine ovarian follicles cultured in vitro

Effects of gonadotropins on the maturation of isolated oocytes and production of progesterone by porcine ovarian follicles from gonadotropin treated gilts have been studied in vitro. The addition of gonadotropins (2 I. U./ml, PMSG, HGC or 2 mg/ml FSH) to the culture medium resulted in increasing the number (84 - 90 %) of isolated oocytes which reached metaphase II. Expansion of the whole cumulus mass was observed only in media containing PMSG, whereas FSH or HCG alone did not cause these marked changes in the cumulus cells. Denudation of the eggs prior to culture gave no significant differences in the maturation rates between oocytes cultured in media with or without gonadotropins. In vitro maturation of follicle-enclosed oocytes took place only in HCG treated animals. Removing the ovary at 15 or 60 minutes after intravenous HCG administration induced oocyte maturation only in 22% and 17% respectively. A sharp increase in the number of oocytes which resume meiosis during follicle culture was observed 4 hours after HCG injection (84 %) and all of the oocytes of the gilts ovariectomized at 8 hours after HCG injection matured during the culture period. The progesterone production of isolated follicles from control gilts (only PMSG injected) increased slowly during a 96-hour culture period (from 48 to 240 ng progesterone/follicle), whereas the secretion of progesterone was drastically increased after a 15 minute interval between HCG injection and ovariectomy (from 42 to 950 ng progesterone/follicle). Follicles removed 24 hours after HCG injection showed a further increase in steroid production (2000 ng progesterone/follicle) and consistently secreted large amounts of progesterone during the culture period.

Oestradiol production by human graafian follicles cultured in vitro

Intact human Graafian follicles recovered during the preovulatory phase of the menstrual cycle and cultured in vitro, gave a mean oestradiol production of 33 ng/hour over periods of 4 to 92 hours. Treatment of follicles with human pituitary gonadotrophin or human chorionic gonadotrophin resulted in an increased production of oestradiol.