Comparative Studies on Lipid Analysis and Ultrastructure in Porcine and Southern Minke Whale (Balaenoptera Bonaerensis) Oocytes

Abstract

Abstract. The present study was conducted to clarify the difference in the color of the cytoplasm in immature follicular oocytes from prepubertal and adult minke whales. The four lipid contents (triglyceride, total cholesterol, phospholipids and non-esterified fatty acids) in vitrified immature oocytes from prepubertal and adult minke whales, and also in fresh and vitrified immature porcine oocytes, were measured. The lipid contents in vitrified-warmed minke whale oocytes were similarly high compared with those in vitrified-warmed porcine oocytes. In particular, the total cholesterol and phospholipid contents in the vitrified immature oocytes from prepubertal and adult minke whales were significantly (P<0.05) higher than those from prepubertal pigs. Furthermore, the distribution of lipid droplets in fresh and vitrified immature oocytes was observed in transmission electron microscopy. Lipid droplets in the prepubertal minke whale oocytes were distributed throughout the cytoplasm. In contrast, adult minke whales had larger lipid droplets which were distributed mainly in the central portion of the cytoplasm. The lipid droplets of immature oocytes from prepubertal pigs were larger than those in minke whale oocytes. These results indicated that the difference in the distribution of the cytoplasmic lipid droplets may result in the difference in the color tone of both prepubertal and adult whale oocyte cytoplasm. Key words: Minke whale, Porcine, Oocytes, Lipid, Sexual maturity (J. Reprod. Dev. 50: [525][526][527][528][529][530][531][532] 2004) e have been studying in vitro maturation (IVM), fertilization (IVF) and culture (IVC) in the artificial production of minke whale embryos [1][2][3][4]. During the studies, we observed a difference in the color of the cytoplasm in immature follicular oocytes from prepubertal and adult minke whales. The cytoplasm of the oocytes collected from prepubertal whales was opaque and dark, whereas the oocytes from adult whales had bright and transparent cytoplasm (Fig. 1). It was considered that the difference in the color of the two oocyte types was related to the lipid content in the cytoplasm. Lipids in the oocytes are mainly involved in energy storage, constitute the c y t o p l a s m i c m e m b r a n e a n d c y t o p l a s m i c organelles, and adjust the physiological function. Lipid analyses in oocytes or embryos have been conducted in domestic animals [5][6][7][8], and it was reported that porcine oocytes had a dark color tone of the cytoplasm as well as minke whale oocytes, and porcine oocytes had higher lipid content than the oocytes of other species [7].Follicular oocytes of many species are very

Fat area and lipid droplet morphology of porcine oocytes during in vitro maturation with trans-10, cis-12 conjugated linoleic acid and forskolin

“…In the present study, we investigated the extent of these variations by measuring LD areas and total area occupied by LD, the fat areas, as well as the relationship of fat area with total oocyte area through the fat oocyte index, before and during porcine oocyte maturation. Moreover, oocytes exhibit distinct colour tones of cytoplasm due to LD content: dark colour and opaqueness in lipid rich ones contrasting with the brightness and transparency of leaner oocytes (Fujihira et al, 2004). Furthermore, Isachenko et al (2003) identified two kinds of LD in porcine oocytes: homogenous, dark looking vesicles and 'gray' looking droplets with electron-lucent streaks.…”

“…The negative effect of an excessive intracellular lipid content of porcine oocytes and embryos on assisted reproductive technologies has been extensively reported (Dobrinsky et al, 1999;Men et al, 2006;. Lipid droplets (LD) are organelles constituted primarily by triacylglycerols and cholesteryl esters surrounded by a monolayer of phospholipids with embedded integral and peripheral proteins, occupying a considerably mass in the eukaryotic cells, particularly in the mammalian oocytes and embryos (Fujihira et al, 2004;Walther and Farese, 2009;Zehmer et al, 2009). LD in porcine oocytes form a dark mass reaching almost all cytoplasm, but their function and importance are scarcely known.…”

“…On the other hand, the intermediate filaments of the cytoskeleton interact directly with these special organelles (Zehmer et al, 2009). Therefore, it is not surprising that during gamete and embryo cryopreservation, morphological variations occurring in LD as consequence of physical changes of lipids lead to irreversible damages in the cytoskeleton (Fujihira et al, 2004;.…”

A Role of Lipid Metabolism during Cumulus-Oocyte Complex Maturation: Impact of Lipid Modulators to Improve Embryo Production

“…The huge number of LD, as well as their distribution pattern or their interaction with other organelles and cytoplasmic pigments, is responsible for the dark colour tone that characterizes the oocyte of some mammalian species, namely, the pig, cattle, horse, or even of the minke whale [19, 37–39]. Although this colour tone seems to be species-specific, it has also been linked to oocyte quality.…”

Attempt at Intracytoplasmic Sperm Injection of In Vitro Matured Oocytes in Common Minke Whales (Balaenoptera acutorostrata) Captured During the Kushiro Coast Survey

“…Iwayama et al [5] vitrified Antarctic mi nk e w ha l e i m m at u r e oo cy te s u s i ng t h e "cryotop" method and obtained a significantly higher maturation rate (29.1%) in adult oocytes than that in prepubertal oocytes (14.4%). Fujihira et al [17] measured lipid concentrations in immature oocytes recovered from prepubertal and adult Antarctic mike whales and found that oocytes from p r e p u b e r t a l w h a l e s h a d h i g h e r l i p i d concentrations, especially triglycerides. They suggested that the high lipid concentrations may have caused the low capacity for cryopreservation in prepubertal whale oocytes.…”