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Biomedical subjects

F Gandolfi

Publications and source records attributed to F Gandolfi.

At least 19 recordsLinked to original sources
PubMed2003

The impact of endocrine disruptors on oocyte competence.

To date, approximately 60 chemicals have been identified as endocrine disruptors: exogenous agents that interfere with various aspects of natural hormone physiology. The potential reproductive and health hazards of these environmental chemicals have recently generated concern among the scientific community, policy makers and general public. The present review presents and discusses the available evidence that environmental chemicals are causing ovarian toxicity in various species, with particular attention to farm animals. The impact of chronic exposure to endocrine disruptors via food and drinking water cannot be neglected when studying fertility problems in these species. This review focuses attention on the superfamily of organochlorine chemicals, persistent organic pollutants (POPs), because of their persistence in the environment, ability to concentrate up the food chain, continued detection in environmental matrices and ability to be stored in the adipose tissue of animals and humans. Published data clearly indicate that POPs disrupt mammalian oocyte maturation and follicle physiology in every species studied so far, including farm animals. However, as most of the data available still derive from experiments performed on laboratory species or in vitro models, great care should be taken when extrapolations to other species or environmental situations are attempted.

Agrochemicals↗
PubMed2002

Evolution of mRNA polyadenylation between oocyte maturation and first embryonic cleavage in cattle and its relation with developmental competence.

In this study we analyzed the pattern of polyadenylation changes that takes place between the resumption of meiosis and the first cleavage of bovine oocytes. Moreover, we investigated whether the delayed occurrence of the first cleavage division, which characterizes embryos of low developmental competence, is accompanied by an altered polyadenylation pattern of individual transcripts. We determined the polyadenylation status of a group of genes that characterize physiological processes, involved in early differentiation (Oct-4), compaction, and cavitation (beta-actin, plakophilin, connexin-32, connexin-43), energy metabolism (glucose transporter type 1, pyruvate dehydrogenase phosphatase), RNA processing (RNA poly(A) polymerase), and stress (heat shock protein 70). RNA was isolated from pools of 20 oocytes or embryos at the germinal vesicle (GV) stage, at the end of in vitro maturation, at the end of in vitro fertilization, and at the time of the first cleavage. Cleavage was assessed 27, 30, 36, 42 hr post insemination (hpi), and at the latter time the remaining uncleaved oocytes were retained as a group. Between oocyte isolation and first cleavage at 27 hpi (best quality embryos), the poly(A) tail of individual transcripts followed four patterns: no changes (beta-actin, PDP); gradual reduction (Cx-43, Oct-4, Plako); gradual elongation (Cx-32, TPA); reduction followed by elongation (PAP, HSP-70, Glut-1). If the interval between insemination and first cleavage was longer than 27 hpi (progressively lower quality embryos) further changes of polyadenylation were observed, which differed for each gene considered. These data indicated that specific changes in polyadenylation contribute to the modulation of gene expression in bovine embryos at this stage of development. Defective developmental competence is accompanied by abnormal polyadenylation levels of specific maternal mRNAs with synchrony between polyadenylation and cleavage emerging as an apparently important factor.

Animals↗
PubMed2002

In vitro production of cattle-water buffalo (Bos taurus--Bubalus bubalis) hybrid embryos.

Interspecific hybrid embryos are useful models for the study of maternal-fetal interactions, transmission pattern of species-specific markers and parental contributions to growth and developmental potential of pre-attachment embryos. In an attempt to investigate the possibility of producing hybrid embryos of domestic cattle (Bos taurus) and water buffalo (Bubalus bubalis), cattle oocytes were exposed to buffalo sperm and buffalo oocytes were exposed to cattle sperm and the cleavage rate and the post-fertilisation features of hybrid embryos up to the blastocyst stage were compared with those of buffalo and cattle embryos. The cleavage rate in buffalo oocytes exposed to cattle sperm was low (40.8%), with only 8.8% of these hybrid embryos reaching the blastocyst stage. Cattle oocytes exposed to buffalo sperm showed 86.3% cleavage, while 25.9% of these attained the blastocyst stage. The speed of development of both types of hybrids was intermediate between that of cattle and buffalo embryos, with hatching occurring on day 7.5 in hybrid embryos, day 8-9 in cattle and day 7 in buffalo. The proportions of cells contributing to the trophectoderm and the inner cell mass were closer to those of the maternal species in both types of hybrid embryos. Our results indicate that cattle-water buffalo hybrid embryos produced using inter species gametes are capable of developing to advanced blastocyst stages and that their in vitro fate, and developmental potential, are influenced by the origin of the oocyte.

Animals↗
PubMed2002

Bovine somatotropin administration to dairy goats in late lactation: effects on mammary gland function, composition and morphology.

We investigated the effects of bovine somatotropin (bST) on mammary gland function and composition in the declining phase of lactation in goats. Sixteen Saanen goats, 180 +/- 11 days in milk (DIM), were divided equally into control and treated groups. The treated group received 120 mg/2 wk of slow-release bST for three cycles. Milk yield, milk composition, milk clotting measures, and plasmin-plasminogen activator activities were recorded weekly. Milk Na and K were determined in individual milk samples collected weekly during the third cycle. Blood samples were collected weekly during the second cycle and the plasma analyzed for nonesterified fatty acids (NEFA), glucose, and urea. At the end of the 6 wk, three goats from each group were slaughtered, and the udders were removed. Mammary gland weight, composition, and total DNA content were determined. The histological effects of bST on mammary tissue were investigated. The analyzed parameters included numbers of alveoli, corpora amylacea, apoptotic cells, and laminin fibronectin distribution and localization. An extensive morphological analysis on the epithelial and stromal components was performed. Milk yield was significantly higher in the treated group, fat content was not affected, but protein and nonprotein nitrogen were lower in treated goats milk. Treatment with bST did not influence milk pH but reduced coagulation time. Plasmin and plasminogen activator activities were not affected. Milk K levels were higher and the Na/K ratio was lower in treated animals. Plasma glucose, NEFA, and urea were unaffected. Mammary gland weight and total DNA were higher in treated than control animals, suggesting that with advancing lactation bST treatment maintains cells. Fat, protein, and collagen content of the mammary tissue did not differ between the groups. Treatment with bST significantly increased the number of lactating alveoli (LA) and significantly reduced the number of regressing alveoli (RA) and corpora amylacea, both within and outside the alveolar lumen. Laminin and fibronectin localization were not affected, and very few apoptotic cells were found in both treated and control samples. Our findings suggest that bST administration to dairy goats in late lactation can modulate mammary gland activity and improve lactation persistency; this is associated with maintained total mammary parenchyma weight and lactating alveoli.

Animals↗
PubMed2001

The influence of cAMP before or during bovine oocyte maturation on embryonic developmental competence.

This study was designed to evaluate the effects of pretreatment with various forms of cAMP before or during bovine oocyte maturation on the acquisition of embryonic developmental competence. The objective of the 4 experiments was to induce differentiation of the early maturing oocyte in conditions of maintained meiotic arrest or normal maturation. To promote differentiation, different forms of cyclic AMP-dependent protein kinase (PKA) pathways were investigated. The factors studied included follicular fluid, invasive adenylate cyclase (iAC), dibutyryl-cAMP (dbcAMP) and 3-isobutyl-1-methyl-xanthine (IBMX) with or without cycloheximide (CHX). High concentrations of iAC pretreatment were beneficial to the oocyte competence in BSA-iAC maturation while harmful in normal maturation. Also, after 2 to 3 h IBMX-iAC pretreatment, another 6 h of CHX treatment with or without iAC was harmful to the embryonic developmental competence of fertilized oocytes even though it did not have any effect on cleavage rate. Experiment 4 was to assess the role of cAMP in acquisition of oocyte developmental competence before meiotic resumption. Results supported that the intracellular cAMP concentration during the interval between oocyte isolation from the follicle and the beginning of in vitro maturation is critical for requiring optimal developmental competence.

1-Methyl-3-isobutylxanthine↗
PubMed2001

The maternal legacy to the embryo: cytoplasmic components and their effects on early development.

RNA molecules and proteins are accumulated in the oocyte cytoplasm during its growth phase and are used to sustain the early phases of embryonic development before embryo DNA transcription begins. This makes the oocyte a very special cell, quite different from somatic cells where RNA and proteins usually undergo a rapid turnover. To enable the storage and timely use of such stored molecules, various mechanisms are effective in the oocyte and are gradually being elucidated. Our understanding of such mechanisms is important for constantly improving therapy for human and animal reproductive disorders as well as for understanding the process of nuclear reprogramming during cloning procedure or stem cell generation. This review focuses on the various aspects of these regulatory processes in an attempt to give an overview of the present knowledge on post-transcriptional and post-translational mechanisms taking place during oocyte maturation and early development. Mechanisms such as cytoplasmic regulation of the poly(A) tail, RNA localization and protein phosphorylation are described in some detail. Because most data are available from lower species these are presented together with appropriate reference to the mammalian oocyte when data are known, or when important differences have been described.

Animals↗
PubMed2001

In vitro reproductive toxicity of polychlorinated biphenyls: effects on oocyte maturation and developmental competence in cattle.

Polychlorinated biphenyls (PCBs) are one of the most persistent and widespread group of endocrine disrupting compounds in the ecosystem. High concentrations of these substances are known to be present in sewage sludge from industrial, agricultural, and domestic origin that is spread in increasing amounts on arable land and pasture as fertilizer and is found in water, representing an increasing risk for the reproductive health of farm animals. Objective of this study was to determine the impact of PCBs on maturation and developmental competence of cattle oocytes. Since PCBs are a family of 209 molecules present in the environment as a mixture, Aroclor-1254, a pool of more than 60 congeners, was used in these experiments as its composition is considered to be environmentally relevant. Cumulus-oocytes complexes were exposed during IVM to serial concentrations of Aroclor-1254 (between 1 microg/ml and 0.0001 microg/ml) and compared with control groups. Aroclor decreased the percentage of oocytes that reached metaphase II stage after 24 hr, at doses as low as 0.01 microg/ml. Groups treated with 0.001 microg/ml or above, showed an impaired fertilization rate and a dramatic increase of polyspermy. Moreover, exposure during maturation resulted in a reduced proportion of oocytes that cleaved and developed until blastocyst stage although no differences in embryo cell numbers were observed. The present study indicates that very low PCBs concentrations are sufficient to disrupt bovine oocyte maturation, its fertilization, and developmental competence. These results also provide a set of reference data for the assessment of the risk posed by these substances to animal reproductive health, though further work will be necessary to equate in vitro doses to in vivo exposures.

Animals↗
PubMed2001

Glucose transporter expression is developmentally regulated in in vitro derived bovine preimplantation embryos.

Glucose is readily been taken up and utilized by preimplantation embryos from different species. However, a comprehensive analysis of the glucose transporter expression throughout preimplantation development is still missing. Here, we have investigated the expression of facilitative glucose transporters (Glut1-5 and 8) and sodium-dependent-glucose transporter (SGLT-I) in bovine oocytes and preimplantation embryos up to d16 of development, using RT-PCR and immunohistochemistry. The embryos were produced in vitro by IVM-IVF. Glut1, Glut3, Glut8, and SGLT-I were expressed in all stages studied. Glut4 transcripts were first detected at the blastocyst stage. Glut2 expression was restricted to the period of blastocyst elongation at d14 and d16. Transcription of the fructose transporter Glut5 started at the 8-/16-cell stage. Our results show a distinct expression pattern for glucose transporters during bovine embryo development in vitro indicating specialized functions for these isoforms at different developmental stages in bovine embryos. Mol. Reprod. Dev. 60:370-376,

Animals↗
PubMed2001

Cellular and molecular mechanisms mediating the effects of polychlorinated biphenyls on oocyte developmental competence in cattle.

Polychlorinated biphenyls (PCBs) can interfere with normal reproductive functions acting as endocrine disruptors. Aroclor-1254 (A-1254), is a pool of more than 60 congeners used for in vitro studies because its composition is representative of PCBs environmental pollution. We previously demonstrated that the exposure of bovine oocytes to A-1254 during in vitro maturation (IVM) was detrimental not only to the maturation process but also induced a significant increase of polyspermy and a reduction of developmental competence. Therefore, we investigated whether A-1254 acts on two processes that occur during IVM and may be related with its negative effects: maternal mRNA polyadenylation and cortical granules (CGs) migration and exocytosis. Bovine cumulus-oocyte complexes (COCs) were exposed to 0.1 microg/ml of A-1254 during IVM, a level of exposure known to affect oocyte maturation, fertilization, and developmental competence. Oocyte exposure to A-1254 altered the poly(A) tail length of 5 out of 10 genes examined. PCBs effect on mRNA polyadenylation was different depending on the gene considered and resulted either in a shorter or in a longer poly(A) tail. At the end of maturation, Aroclor treated oocytes presented clustered CG in a significantly higher percentage than the control group. In addition, CG exocytosis after 8 hr of fertilization occurred at significantly lower extent in zygotes derived from the exposed group compared to control. Our results indicated that the lower developmental competence of oocytes exposed to PCBs during IVM can be related to the interaction of these contaminants with mechanisms regulating maternal mRNA storage in the ooplasm and normal CGs function.

Animals↗
PubMed2001

Oocyte developmental competence after in vitro maturation depends on the persistence of cumulus-oocyte comunications which are linked to the intracellular concentration of cAMP.

Oocyte and cumulus cells are interconnected by an extensive network of gap junctions (GJ) formed by connexin 43. In the present study the functional and morphological status of GJ was investigated during in vitro maturation of bovine oocytes using media known to induce different rates of maturation and developmental competence as well as different levels of cumulus expansion and intracellular concentrations of cAMP. GJ functional condition was studied by microinjection of the fluorescent dye Lucyfer Yellow in cumulus-enclosed oocytes and the intracellular distribution of connexin 43 was examined by immunofluorescence immunocytochemistry. Both functional and morphological analysis of GJ between oocytes and cumulus cells indicated that high maturation and development rates are accompanied by the prolonged persistence of permeable communications, which, however, are independent from cumulus expansion. On the contrary, the premature interruption of such communications was linked to low maturation and development. When these results were correlated to the measurements of intracellular levels of cAMP it was observed that cumulus expansion, GJ permeability and good quality maturation require the highest levels of cAMP. Intermediate cAMP levels determine GJ permeability and good quality maturation in the absence of cumulus expansion while below a threshold level of cAMP, oocyte maturation is defective with a premature interruption of communications through GJ and lack of cumulus expansion which lead to poor development.

Animals↗
PubMed2001

Influence of different stages of the oestrous cycle on cumulus-oocyte communications in canine oocytes: effects on the efficiency of in vitro maturation.

The aim of this study was to investigate the effects of different stages of the oestrous cycle on the communications between dog oocytes and cumulus cells, as well as their possible relationships with the meiotic competence of oocytes matured in vitro. Ovaries were harvested from bitches undergoing anoestrus or late pro-oestrus. Maturation of cumulus-oocyte complexes (COCs) was performed in TCM-199 with 0.3% (w/v) BSA, 0.5 iu FSH ml-1 and 0.5 iu LH ml-1 for 72 h. At the time of collection (0 h), and after 24, 48 or 72 h of culture, some oocytes were stained with Lacmoid to evaluate the nuclear stage of maturation. At 0, 24 or 48 h of in vitro maturation (IVM), oocytes were microinjected (n = 84) with a 3% (w/v) Lucifer yellow solution to evaluate the presence of cumulus-oocyte communications through gap junctions. At t = 0, communications were open in 89% of COCs collected during late pro-oestrus, whereas such communications were not evident in any of the oocytes collected during anoestrus. Communications remained permeable for the first 24 h of maturation in many late pro-oestrous oocytes (67%), whereas no fluorescence diffusion was observed at 48 h of maturation. The presence of cumulus-oocyte communications in late pro-oestrous oocytes was accompanied by their ability to resume meiosis and reach telophase I or metaphase II at higher rates than in oocytes collected during anoestrus (11.1% versus 0%, respectively; P < 0.01). These results indicate that, during anoestrus, there are no permeable gap junctions between oocytes and surrounding cumulus cells at the time of isolation from the ovary. This finding indicates that such oocytes are unsuitable for IVM, as confirmed by their inability to reach telophase I or metaphase II in culture. In contrast, a positive correlation was observed between the presence of permeable gap junctions and meiotic competence in COCs isolated at late pro-oestrus. However, the small proportion of oocytes reaching telophase I and metaphase II indicates that further efforts to define better culture conditions are still required.

Anestrus↗
PubMed2000

Sperm-mediated transgenesis.

The idea of using a sperm cell for introducing exogenous DNA into an oocyte at the time of fertilization would be brilliant if only we were sure that it can be done. Since 1989, contradictory reports have appeared in the literature and, at present, no consensus has been reached on the topic. Given the potential impact of this method for the generation of transgenic animals, for both mammalian and non-mammalian species, this review summarizes what has been achieved in this field. While some aspects, such as the binding of DNA molecules to spermatozoa, have now a solid experimental base, others, such as the generation of real transgenic individuals, are still based on disputed evidence. A critical analysis of the most relevant data will be presented in order to provide the tools for an objective evaluation of the efficiency of this method.

Animals↗
PubMed2000

Effect of cell-to-cell contact on in vitro deoxyribonucleic acid synthesis and apoptosis responses of bovine granulosa cells to insulin-like growth factor-I and epidermal growth factor.

Follicle development is the result of a balanced ratio between cell proliferation and cell death. Previous studies demonstrated differential mitotic responses to insulin-like growth factor (IGF)-I and epidermal growth factor (EGF) of cumulus cells (CC) and mural granulosa cells (MGC). Because cell-to-cell contact seems to modulate the occurrence of programmed cell death, the present experiments investigated the role of cell association in mediating apoptosis and the mitogenic responses to these growth factors of CC and MGC. Cumulus cells were cultured either as intact cumulus-oocyte complexes (COC) or after dissociation with EGTA + sucrose, in the presence of 50 ng/ml IGF-I, 5 ng/ml EGF, or both. Mural granulosa cells from the same follicles were similarly cultured either as cell aggregates or as dissociated cells. Synthesis of DNA was assessed by measurement of [(3)H]thymidine incorporation during the last 6 h of a 24-h culture in TCM199. Percentages of cells undergoing apoptosis were determined immunohistochemically in intact COC and GC aggregates, before and after dissociation as well as after the culture period. Epidermal growth factor and IGF-I stimulated DNA synthesis in both cell types; however, EGF inhibited the action of IGF-I in intact COC but not in MGC. Compared to nondissociated cells, dissociation resulted in a reduction of the mitogenic response of CC to both growth factors and of MGC to EGF. Unlike the response of intact COC to combined treatment with the two growth factors, dissociated CC displayed additive responses to the two growth factors in combination. Addition of denuded oocytes to cultures of dissociated CC enhanced both basal and growth factor-stimulated DNA synthesis but did not restore the inhibitory effect of EGF on the IGF-I response characteristic of intact COC. A significant proportion of intact MGC aggregates underwent apoptosis after 24 h of culture, while no increase of apoptotic cells was observed in intact COC. A dramatic increase in the percentage of apoptotic cells was observed in both CC and MGC when cell-cell contact was interrupted, and EGF and IGF-I were able to partially prevent its occurrence. Taken together these data showed that CC and MGC exhibit qualitatively and quantitatively different responses to IGF-I when cultured in the presence of EGF both in terms of DNA synthesis and onset of apoptosis. Moreover, the disruption of cell-cell contact was a major factor reducing cell proliferation and inducing apoptosis among both subsets of GC.

Animals↗
PubMed1999

Changes in poly(A) tail length of maternal transcripts during in vitro maturation of bovine oocytes and their relation with developmental competence.

Molecules of mRNA are stored in the oocyte cytoplasm in order to be used during the initial phases of embryonic development. The storage takes place during oocyte growth and the extent of poly(A) tail at the 3' end of the transcripts has emerged as an important regulatory element for determining their stability. The objective of the present study was to analyse changes in polyadenylation levels of mRNA transcripts, stored in bovine oocytes, during in vitro maturation and their possible relation with developmental competence. Oocyte developmental competence was predicted on the basis of the morphological appearance of their originating ovary as previously established (Gandolfi et al. 1997a. Theriogenology 48:1153-1160) and were divided into groups H (high competence) and L (low competence). The length of the poly(A) tail of the following genes, beta-actin (beta-Act), connexin 43, glucose transporter type 1, heat shock protein 70, oct-4, plakophilin, pyruvate dehydrogenase phosphatase (PDP), and RNA poly(A) polymerase, was determined at the germinal vesicle (GV) and metaphase II (MII) stage. The results indicated that the poly(A) tail of all genes except for beta-Act and PDP, is shorter after in vitro maturation (IVM) in both groups. Moreover, group L oocytes showed a shorter poly(A) tail than group H oocytes in all genes except for beta-Act and PDP, both at GV and MII stage. We conclude that most of the examined transcripts follow the default deadenylation pattern described during oocyte maturation in other species and that a shorter poly(A) tail is correlated with low developmental competence.

Animals↗
PubMed1999

Effect of different levels of intracellular cAMP on the in vitro maturation of cattle oocytes and their subsequent development following in vitro fertilization.

Serum, gonadotrophins, growth factors, and steroid hormones stimulate the in vitro maturation (IVM) of competent oocytes, acting, directly or indirectly, upon the adenylate cyclase pathway to produce the intracellular messenger, cAMP. The intracellular levels of cAMP in cattle cumulus-oocyte complexes (COC) were manipulated by adding to the collection and maturation media invasive adenylate cyclase (iAC), a toxin produced by the bacterium, Bordetella pertussis. High concentrations of iAC (1 or 5 microgram/ml) in the maturation medium inhibited the resumption of meiosis, while low concentrations (0.1 or 0.01 microgram/ml) resulted in high rates of maturation to the MII stage (92.6 +/- 2.5 and 98.5 +/- 1.4% respectively). The same low concentrations of iAC in the maturation medium resulted in rates of development to the blastocyst stage 8 days post insemination (30.1 +/- 4.2 and 45.1 +/- 3.9%, respectively), which were either not different, or significantly better, than those obtained after IVM in medium supplemented only with serum and gonadotrophins (36.1 +/- 2.9%). Finally, the addition of 0.1 microgram/ml iAC and 0.5 mM 3-isobutyl 1-methylxanthine (IBMX) in the collection medium significantly improved the blastocyst rate when IVM was performed in control medium or medium supplemented with 0.01 microgram/ml iAC (31.9 +/- 5.5 vs. 12.1 +/- 1.6 and 45.5 +/- 2.9 vs. 19.1 +/- 2.3% respectively). It is concluded that the maintenance of an optimal intracellular concentration of cAMP before and during IVM ensures a high developmental competence of bovine oocytes matured in medium without serum and hormones. Mol. Reprod. Dev. 54:86-91,1999.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Molecular cloning, genetic mapping, and developmental expression of bovine POU5F1.

We describe isolation and characterization of the bovine ortholog of POU5F1 (bPOU5F1) encoding octamer-binding transcription factor-4 (Oct-4). The organization of bPOU5F1 is similar to its human and murine orthologs, and it shares 90.6% and 81.7% overall identity at the protein level, respectively. Transient transfection of luciferase reporter constructs in murine P19 embryonal carcinoma cells demonstrated that bPOU5F1 has a functional promoter and contains two enhancer elements, of which one is repressed by retinoic acid. bPOU5F1 was mapped to the major histocompatibility complex on chromosome 23. bPOU5F1 mRNA was detected by nested reverse transcription-polymerase chain reaction in immature oocytes and in in vitro-produced preattachment-stage embryos. Oct-4 in oocytes and in vitro-produced preattachment-stage embryos was demonstrated by indirect immunofluorescence. Confocal laser scanning microscopy revealed Oct-4 in both the inner cell mass and trophoblast cells of the blastocyst until Day 10 of development. Immunofluorescence performed on the outgrowths formed at Day 13 postfertilization from in vitro-produced Day 8 blastocysts showed Oct-4 staining in all cells. This expression pattern suggests that bPOU5F1 acts early in bovine embryonic development but that its expression is not restricted to pluripotent cells of the blastocyst.

Amino Acid Sequence↗
PubMed1998

Comparative analysis of calf and cow oocytes during in vitro maturation.

To determine possible causes of reported differences between developmental competence of oocytes isolated from prepubertal (10- to 14-week-old calves) and adult cows, three parameters were analysed, comparatively, during in vitro maturation (IVM): (1) oocyte diameter, (2) oocyte energy metabolism, and (3) protein synthesis of oocytes and cumulus cells. Cumulus-oocyte complexes were isolated from follicles of 3-5 mm in diameter in both age groups. Mean oocyte diameter was smaller (P < 0.02) in calves than in cows (118.04 +/- 1.15 versus 122.83 +/- 0.74 microns). During the first 3 hr of IVM, calf oocytes metabolised glutamine and pyruvate at lower rates than adult oocytes, but after 24 hr of culture, both molecules were metabolised at the same rate as for adult oocytes. A significant decrease in protein synthesis, as measured by [35S]methionine and [35S]cysteine incorporation was recorded after 9 hr of IVM in calf oocytes, while in adult oocytes a significant decrease in protein synthesis was detected only after 24 hr. After the first 3 hr of maturation, proteins of 130, 26, and 24 kDa were more abundant in adult than in calf oocytes, while a protein of 55 kDa was more visible in calf than in adult oocytes. At the same time, among proteins newly synthesised by cumulus cells, molecules of 405, 146, 101, and 77 kDa were more abundant in adults than in calves. In conclusion, calf oocytes and cumulus cells showed several differences when compared with their adult counterparts, which are consistent with their reported lower developmental competence.

Aging↗