Effect of different vitrification protocols on post thaw viability and gene expression of ovine preantral follicles

The aim of the present study was to establish a vitrification protocol for ovine preantral follicles, which can retain viability after thawing and to evaluate the impact of different vitrification treatments on apoptosis and development-related gene expression. Preantral follicles were isolated from cortical slices of ovaries by the mechanical method of isolation. The isolated preantral follicles (200-300 μm) were randomly assigned into four groups. Group1 - Control Fresh preantral follicles (256 follicles); Group 2- Vitrification treatment A (259 follicles) (Vitrification solution 1 (VS1) - Fetal bovine serum (FBS)10%, Ethylene glycol (EG):1.8 M, Dimethyl sulfoxide (DMSO): 1.4 M, Sucrose-0.3 M for 4 min; VS2- FBS10%, EG:4.5 M, DMSO: 3.5 M, Sucrose:0.3 M for 45 s), Group 3 - Vitr. treatment B (235 follicles) (VS1-FBS 20%, EG:1.3 M, DMSO1.05 M for 15 min, VS2- FBS 20%, EG:2.7 M, DMSO:2.1 M for 5 min) and Group 4-Vitrification treatment C (248 follicles) (VS1-Glycerol(Gly):1.2 M for 3 min, VS2- Gly:1.2 M, EG:3.6 M for 3 min, VS3- Gly3M, EG: 4.5 M for 1 min). Preantral follicles were placed in corresponding vitrification treatments and later plunged immediately into liquid nitrogen (-196 °C). After a week, the follicles were thawed and analyzed for follicular viability by trypan blue dye exclusion method as well as for gene expression. The results showed that the low concentration of cryoprotectants (vitrification treatment B) negatively affected the viability of preantral follicles in comparison with control follicles. There was no significant difference in the viability rates among the Control (87%), Treatment A (79%) and Treatment C (75%). The percentage of viable preantral follicles (73%) derived from Treatment B was significantly decreased (P<0.05%) in comparison to that of control. The expression of apoptotic gene BAK was higher in the vitrification treatment B group. Expressions of the other apoptosis-related genes i.e. Bcl2L1, BAD, BAX, Caspase 3, and Annexin showed no significant difference among the groups. The expression pattern of development competence genes GDF-9 and BMP-15 were higher (P < 0.05) in vitrification treatment A and C, respectively. Expression of NOBOX gene was significantly increased in preantral follicles with Vitrification treatment B compared to the control group. We conclude that both the Vitrification treatment A and Treatment C were the efficient vitrification treatment methods for the vitrification of ovine preantral follicles.

Effect of retinol in the vitrification medium on viability of vitrified ovine preantral follicles and expression of key developmental and apoptosis related genes

BACKGROUND

Vitrification increases the production of reactive oxygen species (ROS) and the antioxidants in the vitrification solution may be beneficial by reducing excessive ROS production.

OBJECTIVE

To evaluate the effect of retinol supplementation in vitrification solution on viability, apoptosis and development-related gene expression in vitrified sheep preantral follicles.

MATERIALS AND METHODS

Preantral follicles were isolated and randomly assigned into one of five groups: Group1, control fresh preantral follicles; Group 2, vitrification treatment; Group 3, vitrification + 2 μM retinol; Group 4, vitrification + 5 μM retinol; Group 5, vitrification + 10 μM retinol. Preantral follicles were placed in vitrification solutions and then plunged into liquid nitrogen (-196°C). After a week, the follicles were thawed and analyzed for follicular viability by trypan blue exclusion method and for gene expression.

RESULTS

Vitrification with 5 μM retinol positively affected viability in comparison with vitrification without retinol (P < 0.05). There was no significant difference in viability among the Group 1, Group 2, Group 3 and Group 5. Expression of apoptotic genes BAX and Casp 3 were higher in the vitrified group, and vitrification with 5 μM retinol (Group 4) is comparable to the control fresh. Expressions of other apoptosis-related genes (i.e., BCL2L1, BAD and BAK) showed significant difference between the control fresh group and the vitrification group with 5 μM retinol. Expression of Annexin5 was also significantly different among various groups. The expression of development competence genes GDF-9 and BMP-15 were higher (P < 0.05) in the Group vitrified with 5 μM retinol.

CONCLUSION

The supplementation of 5 μM retinol in vitrification solution was beneficial for the vitrification of ovine preantral follicles.

Effect of retinol as antioxidant on the post-thaw viability and the expression of apoptosis and developmental competence-related genes of vitrified preantral follicles in buffalo (Bubalus bubalis)

The present study evaluated the effect of supplementation of retinol in the vitrification solution on the viability, apoptosis and development-related gene expression in vitrified buffalo preantral follicles. Preantral follicles isolated from cortical slices of ovaries were randomly assigned into three groups: Group1-Control fresh preantral follicles; Group 2-Vitrification treatment (Vitrification solution 1 (VS1) -TCM-199 + 25 mM HEPES + Foetal bovine serum (FBS) 10%, Ethylene glycol (EG): 10%, Dimethyl sulphoxide (DMSO): 10%, Sucrose-0.3 M for 4 min; VS2- TCM-199 + 25 mM HEPES + FBS10%, EG:25%, DMSO: 25%, Sucrose:0.3 M for 45 s); Group3-vitrification treatment +5 μM of Retinol. Preantral follicles were placed in corresponding vitrification medium and plunged into liquid nitrogen (-196°C). After a week, the follicles were thawed and analysed for follicular viability and gene expression. There was no significant difference in the viability rates among the Group 1(Fresh preantral follicles) (91.46 ± 2.39%), Group 2 (89.59 ± 2.46%) and Group 3 (87.19 ± 4.05%). There was a significantly (p < .05) higher mRNA expression of BCL2L1, GDF-9 and BMP-15 in the vitrification + retinol group compared with the control group. There was a significantly (p < .05) higher expression of Caspase-3 and Annexin-5 in the vitrification group and Vitrification + retinol group compared with control group of follicles. It is concluded that the supplementation of 5 μM of Retinol in Vitrification solution was an efficient vitrification procedure for the vitrification of buffalo preantral follicles.

Disturbed spermatogenic signaling in pituitary adenylate cyclase activating polypeptide-deficient mice

PACAP is a neuropeptide with diverse functions in various organs, including reproductive system. It is present in the testis in high concentrations, and in addition to the stage-specific expression within the seminiferous tubules, PACAP affects spermatogenesis and the functions of Leydig and Sertoli cells. Mice lacking endogenous PACAP show reduced fertility, but the possibility of abnormalities in spermatogenic signaling has not yet been investigated. Therefore, we performed a detailed morphological analysis of spermatozoa, sperm motility and investigated signaling pathways that play a role during spermatogenesis in knockout mice. No significant alterations were found in testicular morphology or motility of sperm in homozygous and heterozygous PACAP-deficient mice in spite of the moderately increased number of severely damaged sperms. However, we found robust changes in mRNA and/or protein expression of several factors that play an important role in spermatogenesis. Protein kinase A expression was markedly reduced, while downstream phospho-ERK and p38 were elevated in knockout animals. Expression of major transcription factors, such as Sox9 and phospho-Sox9, was decreased, while that of Sox10, as a redundant factor, was increased in PACAP-deficient mice. The reduced phospho-Sox9 expression was partly due to increased expression and activity of phosphatase PP2A in knockout mice. Targets of Sox transcription factors, such as collagen type IV, were reduced in knockout mice. In summary, our results show that lack of PACAP leads to disturbed signaling in spermatogenesis, which could be a factor responsible for reduced fertility in PACAP knockout mice, and further support the role of PACAP in reproduction.

Relationship between Paratuberculosis and the microelements Copper, Zinc, Iron, Selenium and Molybdenum in Beef Cattle

To study the deficiency of minerals and its relationship with Paratuberculosis, blood, serum, and fecal samples were obtained from 75 adult bovines without clinical symptoms of the disease and from two bovines with clinical symptoms of the disease, from two beef herds with a previous history of Paratuberculosis in the Province of Buenos Aires, Argentina. Serum samples were processed by ELISA and feces were cultured in Herrolds medium. Copper, zinc and iron in serum were quantified by spectrophotometry and selenium was measured by the activity of glutathione peroxidase. We also determined copper, zinc, iron and molybdenum concentrations in pastures and the concentration of sulfate in water. Mycobacterium avium subsp paratuberculosis (Map) was isolated from 17.3% of fecal samples of asymptomatic animals and from the fecal samples from the two animals with clinical symptoms. All the Map-positive animals were also ELISA-positive or suspect, and among them, 84.6% presented low or marginal values of selenium and 69.2% presented low or marginal values of copper. The two animals with clinical symptoms, and isolation of Map from feces and organs were selenium-deficient and had the lowest activity of glutathione peroxidase of all the animals from both herds. All the animals negative to Map in feces and negative to ELISA had normal values of Se, while 13.8% of animals with positive ELISA or suspect and culture negative presented low levels of Se. Half of the animals that were negative both for ELISA and culture in feces were deficient in copper but none of them presented low values of selenium. The content of molybdenum and iron in pasture was high, 2.5 ppm and 1.13 ppm in one herd and 2.5 ppm and 2.02 ppm in the other, respectively, whereas the copper:molybdenum ratio was 1.5 and 5.2, respectively. These results do not confirm an interaction between imbalances of the micronutrients and clinical Paratuberculosis, but show evidence of the relationship between selenium deficiencies in animals with Map infection and ELISA positive results.

Assisted reproductive technologies in the reproductive management of small ruminants

In modern agriculture, assisted reproductive technologies are being used for out of season oestrus induction, enhancement of reproductive performance and genetic improvement. In addition, they can have substantial contribution in preservation of endangered species or breeds, as well as in eradication programs of various diseases. While their applications are widespread in cattle, in small ruminants it is almost restricted to artificial insemination. The main limitations of a wider application in small ruminants are the naturally occurring anoestrus period, the variability of response to superovulatory treatments, the fertilisation failure and the need of surgery for collection and transfer of gametes and embryos. Nonetheless, during the last 30 years, considerable progress has been made in sheep and goat embryo technologies, especially in the fields of oestrus synchronisation, superovulation and in vitro embryo production. This paper reviews the status of assisted reproductive technologies in sheep, analysing the prospects offered by recent advances in in vivo and in vitro embryo production from mature and juvenile lambs.

Matrix metalloproteinase activity assays: Importance of zymography

INTRODUCTION

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases capable of degrading extracellular matrix, including the basement membrane. MMPs are associated with various physiological processes such as morphogenesis, angiogenesis, and tissue repair. Moreover, due to the novel non-matrix related intra- and extracellular targets of MMPs, dysregulation of MMP activity has been implicated in a number of acute and chronic pathological processes, such as arthritis, acute myocardial infarction, chronic heart failure, chronic obstructive pulmonary disease, inflammation, and cancer metastasis. MMPs are considered as viable drug targets in the therapy of the above diseases.

METHODS

For the development of selective MMP inhibitor molecules, reliable methods are necessary for target validation and lead development. Here, we discuss the major methods used for MMP assays, focusing on substrate zymography. We highlight some problems frequently encountered during sample preparations, electrophoresis, and data analysis of zymograms.

RESULTS AND DISCUSSION

Zymography is a widely used technique to study extracellular matrix-degrading enzymes, such as MMPs, from tissue extracts, cell cultures, serum or urine. This simple and sensitive technique identifies MMPs by the degradation of their substrate and by their molecular weight and therefore helps to understand the widespread role of MMPs in different pathologies and cellular pathways.

68 VITRIFICATION OF CLEAVAGE-STAGE MOUSE EMBRYOS BY THE VITROLOOP™ (CRYOLOOP) PROCEDURE

By decreasing the volume of the cryoprotective solution, we were able to dramatically increase the freezing speed and decrease the toxicity and osmotic side effects of the cryoprotectants (CP). Several carriers have been developed successfully (Vajta G et al. 1998 Mol. Reprod. Dev. 51, 53–58; Liebermann J et al. 2002 Reprod. Biomed. Online 4, 146–150; Park SP et al. 1999 Hum. Reprod. 15, 1787–1790; Chung HM et al. 2000 Fertil. Steril. 73, 545–551; Kuwayama M and Kato O 2000 Fertil. Steril. 74(Suppl. 3), S49 O-127; Matsumoto H et al. 2001 Cryobiology 42, 139–144; Lane M et al. 1999 Fertil. Steril. 72, 1073–1078; Dinnyés A et al. 2000 Biol. Reprod. 63, 513–518). The objective of our study was to vitrify Day 3 cleavage stage mouse embryos with the Vitroloop™ (Vitrolife, Kungsbacka, Sweden) cryopreservation technology. Vitrification was carried out in RapidVit™ Cleave (Vitrolife) solutions (holding, equilibration, and vitrification medium). Embryos were exposed to a 2-step loading of CP, ethylene glycol (EG), and propylene glycol (PG), before being placed in a small loop attached to the lid of a cryo-vial and rapidly submerged into liquid nitrogen (LN). First, the embryos were transferred from the G-MOPS holding medium to the equilibration medium containing 8% EG for 2 min. Then, embryos were transferred into a 20-μL drop of vitrification medium containing 16% EG, 16% PG, 10 mg mL–1 Ficoll 400, and 0.65 m sucrose for 30 s. After that, the embryos (maximum of 2 at a time) were transferred onto the loop, which was quickly sealed in a cryo-vial of LN and stored. After storage in LN, embryos were warmed by a 3-step dilution of the CP with sucrose (RapidWarmCleave™, Vitrolife) carried out at 37°C. First, the loop with the embryos was quickly immersed in 37°C warming medium 1 (0.65 m sucrose) for 20 s. Then, the embryos were transferred into warming medium 2 (0.25 m sucrose) for 1 min, then into warming medium 3 (0.125 m sucrose) for 2 min, and finally into warming medium 4 (G-MOPS medium) for 5 min. Following warming, embryos were cultured in G1 medium (Vitrolife) at 37°C with 6.5% CO2 and maximum humidity in air. Embryo viability was assessed by 48 h in vitro culture; the survival of embryos was based on morphological appearance in vitro after thawing and continued development to expanded blastocysts upon subsequent culture. The control embryos were treated likewise except that they were not vitrified. A total of 229 cleavage-stage embryos were vitrified and warmed; out of these, 11 were lost (11/229; 4.8%). Of the remaining 218 embryo, 202 survived vitrification (202/218; 92.7%) and 180 developed further to expanded blastocysts during in vitro culture (180/202; 82.6%). In the control group, 91.4% of the embryos developed to expanded blastocysts (75/82) indicating that the solutions used were not toxic. Our data show that a high percentage of cleavage-stage mouse embryos survived vitrification in the mixture of EG and PG combined with the use of cryoloop and developed normally in vitro after thawing. To our knowledge, this is the first report of the successful use of the Vitroloop™ vitrification procedure with cleavage-stage mouse embryos. The authors thank Vitrolife Ltd. (Kungsbacka, Sweden) and FertiCad Ltd. (Budapest, Hungary) for providing the solutions. The 3-month fellowship for Phillip Klambauer was provided by CEEPUS.

Endocrine characteristics of late pregnant hyperketonaemic ewes and their reproductive performance following the induction of ovarian cyclicity out of the breeding season

Ketosis was diagnosed in a flock of Merino ewes that conceived from synchronised oestrus in the early autumn period. On day 140 of pregnancy the ewes were sampled for determination of betaOH-butyrate (BHB), AST, glucose, non-esterified fatty acids (NEFA), total cholesterol (TCH), insulin, T4, T3, cortisol, IGF-1 and leptin. The results were evaluated according to the number of fetuses born some days later and the presence of hyperketonaemia (BHB: > or = 1.60 mmol/l). In May, about 3 months after lambing, cyclic ovarian function was induced (Cronolone + eCG), and the ewes were inseminated artificially (AI) 48 h after the removal of gestagen-containing sponge. At the time of AI and 10 days later blood samples were collected again to check the plasma levels of the same constituents as previously (in samples taken at AI), and to monitor the ovarian response by assaying progesterone (in both samples). On day 140 of gestation significantly lower BHB levels were detected in dams with single (n = 41) than in those with twin (n = 57) pregnancies. Hyperketonaemia was found only in ewes bearing twins (n = 27). These animals had higher NEFA and cortisol, and lower TCH, insulin, IGF-1, leptin and T3 levels than their normoketonaemic twin-bearing flock-mates, and those with single pregnancy. The blood glucose concentrations varied within a wide range, and the means of groups did not exhibit any significant differences. The formerly hyperketonaemic individuals were characterised by lower leptin level 3 months after lambing, and they showed a poorer response to the cycle-induction procedure than the others. The non-responders had lower IGF-1 and leptin levels than those ovulated after this treatment. It was concluded that the subclinical form of ovine ketosis is characterised by complex endocrine alterations, reflecting an obvious form of negative energy balance. If attempts to induce cyclic ovarian function outside the breeding season are made soon after lambing, the ovarian response and fertility of these ewes may also be depressed.

87 THE EFFECT OF LOW TEMPERATURE ON THE DETECTABILITY/VISUALIZATION OF THE MEIOTIC SPINDLE IN MII MOUSE OOCYTES

The polscope uses novel electrooptical hardware and digital processing to image macromolecular structures in cells on the basis of their birefringence (Sato et al. 1975 J. Cell Biol. 76, 501-517). Imaging of the spindle in living oocytes with the polscope is based on birefringence of an inherent physical property of the microtubules. De-polymerization of microtubules arrests meiosis and induces abnormal meiosis generating chromosomally abnormal oocytes which are not capable of being fertilized and developing. In this study we examined whether spindles in living mouse oocytes can be safely imaged/examined by the polscope and investigated the influence of sub-optimal temperature on spindle detection/visualization. For oocyte collection, 6- to 8-week-old CB6F1 female mice were superovulated with PMSG (10 IU, i.p.; Sigma, USA) and 46 to 48 h later they were injected with hCG (10 IU, i.p.; Sigma). Oocytes were collected 20 to 23 h after hCG treatment in MOPS buffered medium (G-MOPS"; Vitrolife, Sweden AB, Kungsbacka, Sweden) supplemented with human serum albumin (HAS"; Vitrolife). Cumulus cells were removed from the zonae pellucidae by exposure to a solution of 40 IU/mL hyaluronidase (HYASE"; Vitrolife). For spindle examination, each oocyte was placed in a 5-�L drop of G-MOPS medium, covered with oil (Ovoil; Vitrolife), and examined in a Delta T.C.O. dish with a specially coated glass bottom (Willco-Dish, Willco Wells, Amsterdam, The Netherlands). Oocytes were imaged by a Nikon Diaphot microscope with a video camera, objective lens, and controller, combined with a computerized imaging analysis system (CRI, Great Britain). For evaluation of the effect of sub-optimal temperature on the visualization/detection of the spindle, mouse oocytes were cultured for a short period of time at sub optimal temperatures (18 to -20�C/25 min and -10 to -15�C/2 min). After that, the oocytes were immediately checked for presence and condition of the meiotic spindle and re-checked after 30-min culture at 37�C with 6% CO2, 5% O2, 89% N2 and maximal humidity in air. There was no difference in the detect ability of the spindle in mouse oocytes with or without polar body (PB+: 21/24, 87%; PB-: 29/32, 90%). We found that the treatment with sub-optimal temperature has an effect to the spindle visualization. Immediately after treatment, the spindle could be detected in 80% of the oocytes (16/20). However, after 30-min culture, the meiotic spindle was detectable in only 25% of the treated oocytes (5/20; P < 0.05). Sub optimal temperature at first increased the birefringence of the meiotic spindle for a short period of time; then the spindle became completely undetectable. The increased sensitivity of the meiotic spindle to low temperature is one of the biggest obstacles to the oocyte cryopreservation. Our results provide further evidence that the spindle in mammalian oocytes is very sensitive to temperature fluctuations. The increase in the birefringence was the first sign that the structure of microtubules and other cytoskeletal factors forming the spindle had changed. Investigations are underway to learn more about the capability of the meiotic spindle to become reorganized.

Survival of mouse blastocysts after low-temperature preservation under high pressure

Cryoinjuries are almost inevitable during the freezing of embryos. The present study examines the possibility of using high hydrostatic pressure to reduce substantially the freezing point of the embryo-holding solution, in order to preserve embryos at subzero temperatures, thus avoiding all the disadvantages of freezing. The pressure of 210 MPa lowers the phase transition temperature of water to -21 degrees C. According to the results of this study, embryos can survive in high hydrostatic pressure environment at room temperature; the time embryos spend under pressure without significant loss in their survival could be lengthened by gradual decompression. Pressurisation at 0 degrees C significantly reduced the survival capacity of the embryos; gradual decompression had no beneficial effect on survival at that stage. Based on the findings, the use of the phenomena is not applicable in this form, since pressure and low temperature together proved to be lethal to the embryos in these experiments. The application of hydrostatic pressure in embryo cryopreservation requires more detailed research, although the experience gained in this study can be applied usefully in different circumstances.

12PREDICTION OF BULL FERTILITY BY COMPUTER ASSISTED SEMEN ANALYSIS

Sperm motility is clearly essential for fertilization both in vivo and in vitro. Motility is necessary for successful sperm transport, a step that is bypassed with in vitro fertilization. Recently, increasing attention has been paid to the objective evaluation and characterization of sperm motility more than simply determining the total proportion of motile spermatozoa. The purpose of computerassisted semen analysis (CASA) is to provide values for sperm concentration and sperm motility more rapidly and accurately than those obtained with traditional semen analyses methods. The objective of our experiment was to investigate the effect of specific aspects of sperm movement, such as the velocity of progression and the actual pattern of movement, to the fertilizing capability of sperm. Frozen semen samples of 10 HF breeding bulls were used in the study. For the motility analyses, Medealab CASA system (Medealab, Germany, Ver. 4.1) was used, and the velocity parameter of VCL (curvalinear velocity, μms−1), VSL (straight line velocity, μms−1), and VAP (average path velocity, μms−1) were evaluated and compared with the Day 30 and 75 non−return rates (NR30 and NR75). For every sample, a total of 10 fields were examined for 8s using a disposable 20 micron capillary chamber (CellVision, USA) giving a total of 1165 to 2831 cells evaluated. Chi square analysis, analyses of variance and linear correlation coefficient was applied to the statistical evaluation and comparison of the results. Data are based on weighted values. From the same batch of the analyzed frozen semen, a total of 8099 females were inseminated in more than 100 farms with a total of 6590 animals being positive for pregnancy at Day 30 and 4525 animals at Day 75. Within the bulls, differences were found in the values of NR30 and NR75 (P&lt;0.05). Our data indicate very strong differences between the males’ NR30 and NR75 values (NR30: 65.6%±13.04 to 79.6%±11.17; P&lt;0.001 and NR75: 37.8%±10.38 to 58.3%±15.53; P&lt;0.001) reflecting the individual differences in the fertilizing capability of the males. All velocity parameters show very high correlation with strong significance both non−return rates but the best values belong to VAP (NR30 and NR75; P&lt;0.02). Our data indicate that the bulls with lower VCL (25.51±33.04 to 79.54±58.03), VSL (11.35±19.45 to 36.36±35.71), and VAP (12.67±19.06 to 41.75±34.45) values showed lower fertilization rates both at NR30 and NR75. Computer and video technologies have advanced rapidly in recent years; thus the capability and accuracy of the latest versions of CASA systems are considerably better and they give more information about the different motion characteristics of spermatozoa. Because of the vital role of sperm motility in the reproductive process, such systems will enable us to move into a new era of diagnostic andrology and predict the fertilizing capability of semen. Supported by NKFP-Grants 4/040/2001 and 4/031/2001.

117EFFECTS OF PREVIOUS PRESSURE TREATMENT ON THE SURVIVAL AND DEVELOPMENTAL SPEED OF EXPANDED MOUSE BLASTOCYSTS FROZEN RAPIDLY (PILOT STUDY)

It has been demonstrated that embryos can survive exposure to a substantial amount of pressure. (Pribenszky et al., 2003 Theriogenology 59, 329, and 2002 Theriogenology 57, 506). Other studies report that, if a biological system is challenged by certain stresses, its ability to react and survive other stresses can be improved. The aim of our present study was to examine whether the survival rate of expanded mouse blastocysts could be improved by a certain pressure treatment before the freezing procedure. Morula stage mouse embryos were collected and cultured at 37°C with 5% CO2 and maximal humidity in air in G 2.2 medium (Vitrolife, Göteborg, Sweden) to the expanded blastocyst stage. Embryos were randomly allocated to three groups. Embryos in Group I were equilibrated for 5 minutes in a solution containing 1.5M ethylene glycol (EG) and 0.25M sucrose in M2 (Sigma, St. Louis, MO, USA), supplemented with 10% FCS (Sigma), and then transferred into a vitrification solution (7M EG, 0.5M sucrose in M2 with 10% FCS) pre-loaded in a 0.25-ml plastic straw (7–9 embryos/straw). After 1-min exposure to the vitrification solution, the straw was slowly immersed in liquid nitrogen. Embryos in Group II were loaded into 0.08-mL straws (7–9 embryos/straw) with M2. Straws were placed into the chamber, filled with M2, of a special laboratory-made device that is capable of generating and precisely detecting hydrostatic pressure up to 150MPa (1500atm), and were exposed to 60MPa pressure for 30min. After the pressure treatment, embryos were frozen as described above. Straws were thawed by transfer into 30°C water for 30s and then the embryos were recovered and placed in rehydration medium (0.5M sucrose in M2 supplemented with 10% FCS) for 5min. Embryos then were cultured in medium G2.2 as described above. A total of 27, 29 and 26 embryos were assigned to Group I, Group II and the untreated control group, respectively. Embryo viability and development were assessed at 6 and 20h after culture as determined by morphological appearance and hatching. At 6h, 16% (4/27) of the non-pressurized embryos were one-half expanded, at 20 hours 37% (10/27) were two-thirds and 30% (8/27) were one-half expanded; none of them were hatching. While at the pressure treated groups 89% (26/29) of the embryos were fully expanded at 6 hours, and 68% (20/29) were hatching at 20h (untreated: 25/26 fully expanded at 6h, 24/26 hatched at 20h). Data were analyzed by chi-square test. We considered embryos which were at least two-thirds expanded. After 6 hours Group I differed from Group II and the control (P&lt;0.01). There was no significant difference between Group II and the control (P&lt;0.01). After 20 hours the same relations were seen. In the case of hatching, Group I differed from Group II and the control (P&lt;0.01). There was no significant difference between Group II and the control (P&lt;0.05). According to our results, the applied pressure treatment improved the in vitro development of the embryos after freezing. The re-expansion was faster and the survival rate was higher for those embryos that received pressure treatment before cryopreservation. Further experiments are needed to confirm and explore the in vitro and in vivo effects and benefits of pressure treatment before freezing.

Assisted reproductive research: laser assisted hatching and spindle detection (spindle view technique)

Animal experiments are very important for the development of new assisted reproductive techniques (ART) for use in human and animal reproductive medicine. Most technical aspects of reproductive manipulation of humans and animals are very similar, and many components of successful human ART used nowadays have been derived from animal studies. In this study we examined (1) the use of 'non-contact' laser for assisted hatching, (2) whether spindles in living mouse oocytes could safely be imaged/examined by polarisation microscope (polscope) and (3) the influence of environment (e.g. temperature, in vitro culture, etc.) on spindle detection/visualisation. The data of the study presented here show that (1) laser assisted hatching (AH) is a fast, very accurate and safe procedure without any harmful effect on embryo development and it can support very effectively the implantation of embryos, (2) the use of polscope facilitates the evaluation of oocyte quality and the selection of oocytes with spindle, (3) by monitoring the spindle position during intracytoplasmic sperm injection (ICSI), we can reduce spindle damage and increase the chance of fertilisation. Further studies are underway to test the hypothesised connection between spindle birefringence and developmental capacity of oocytes/embryos.

Effect of the El Niño phenomenon on the ovarian responsiveness and embryo production of donor cows

The effects of different Temperature Humidity Index (THI) values in cold, hot and El Niño (EN) climates on superovulation and embryo production were analysed on Holstein Friesian donor cows. There were significant differences in the THI among the three climates. The average temperature in the EN period was 6 degrees C higher than in the summer period of the previous 30 years. The number of corpora lutea (CL) and embryos were log- and back-transformed, Kolmogorov-Smirnoff test was used for normality and Lilliefors test was applied for significance. In the cold season THI was 70.74 +/- 1.35 and the average number of CL was 9.84 +/- 4.37. In the hot season the THI was 73.99 +/- 0.72 and the average number of CL was 9.70 +/- 4.49. When the THI, in the EN period, increased up to 79.74 +/- 4.01, the superovulation response was significantly (P < 0.01) reduced (average number of CL = 5.22 +/- 2.53). The embryo production result showed a similar tendency. In the hot period the average number of embryos obtained was 5.87 +/- 2.98. However, in the EN period it decreased to 4.21 +/- 2.05. Higher temperature reduced embryo quality. The proportion of live embryos (%) was 59.2 +/- 37.4 in the cold and 38.2 +/- 38.5 in the EN periods of the year (P < 0.01). However, ovarian sensitiveness showed adaptation to summer environment while the heat stress, which was more severe in the EN period, negatively affected the superovulation response and embryo production.

Studies on factors affecting superovulation and embryo transfer in Hungarian merino ewes

The objectives of this study were (a) to assess the ovulatory response and embryo production of Hungarian Merino ewes after superovulation, (b) to investigate the factors influencing the efficiency of embryo transfer (ET) in Hungarian Merino ewes, (c) to compare the results of two ovarian stimulation protocols (PMSG and PMSG + FSH treatment) in Hungarian Merino ewes, and (d) to study how superovulation, laparoscopic insemination and surgical embryo retrieval (ER) affect the subsequent reproduction of Hungarian Merino donor females after an ET programme. There was no significant difference between the ovarian stimulation protocols in the ratio of donor ewes responding to superovulation nor in the average number of corpora lutea. However, the number of transferable embryos recovered per donor ewe was higher in the PMSG + FSH group. The proportion of transferable embryos, unfertilized oocytes and degenerated embryos did not differ between the treatment protocols. The total pregnancy rate was 53.4% (179/335). Neither the developmental stage of the embryo nor the number of transferred embryos affect the implantation of embryos. However, the increased number of transferred embryos positively influenced the pregnancy rate. No difference was found in the pregnancy rate between synchronised and non-synchronised groups of recipients. Thirty-six out of 45 donor ewes (80%) became pregnant within one year after the ET programme, indicating that ovarian stimulation and surgical ER did not affect adversely their reproduction.

Superovulation using recombinant human FSH and ultrasound-guided transabdominal follicular aspiration in baboon (Papio anubis)

The response of baboon females to a modified human ovarian stimulation protocol incorporating start of pituitary suppression in the luteal phase of the cycle with a GnRH agonist (GnRHa) and recombinant human FSH (rhFSH) was studied. A long-acting GnRHa implant supplying goserelin acetate was administered s.c. to six adult female baboons experiencing regular menstrual cycles (33-34 days) on days 22-24 of the cycle. Follicular development was monitored by transabdominal ultrasonography and serum levels of E2 and progesterone (P4) and rhFSH were determined by ELISA. Menses occurred 9-10 days after GnRHa administration. Daily i.m. administration of 75 IU rhFSH commenced 9-10 days after menses and continued for 9-10 days. When most follicles were > or =5mm diameter and serum E2 had reached its maximum level, 2000 IU hCG was administered i.m. to induce follicle maturation. Transabdominal ultrasound-guided follicular aspiration of follicles > or =2mm diameter was performed 30-34h after hCG administration. One baboon did not show an adequate response to rhFSH stimulation. This animal did not receive further treatment and no data for it are presented. The number of follicles aspirated was 21+/-4 and 17.2+/-3.8 oocytes were recovered per animal with an average recovery rate of 82% (86/105). The number of oocytes collected from five animals were 14, 21, 16, 15, and 20 (n=86). Most of the oocytes recovered were in metaphase II and 3h after recovery 91% (78/86) were considered suitable for in vitro fertilization. It was concluded that recombinant human FSH can successfully induce follicular recruitment and oocyte maturation in baboon females during pituitary suppression with a GnRHa

Substrate specificities of recombinant mannan-binding lectin-associated serine proteases-1 and -2

Mannan-binding lectin (MBL)-associated serine proteases-1 and 2 (MASP-1 and MASP-2) are homologous modular proteases that each interact with MBL, an oligomeric serum lectin involved in innate immunity. To precisely determine their substrate specificity, human MASP-1 and MASP-2, and fragments from their catalytic regions were expressed using a baculovirus/insect cells system. Recombinant MASP-2 displayed a rather wide, C1s-like esterolytic activity, and specifically cleaved complement proteins C2 and C4, with relative efficiencies 3- and 23-fold higher, respectively, than human C1s. MASP-2 also showed very weak C3 cleaving activity. Recombinant MASP-1 had a lower and more restricted esterolytic activity. It showed marginal activity toward C2 and C3, and no activity on C4. The enzymic activity of both MASP-1 and MASP-2 was specifically titrated by C1 inhibitor, and abolished at a 1:1 C1 inhibitor:protease ratio. Taken together with previous findings, these and other data strongly support the hypothesis that MASP-2 is the protease that, in association with MBL, triggers complement activation via the MBL pathway, through combined self-activation and proteolytic properties devoted to C1r and C1s in the C1 complex. In view of the very low activity of MASP-1 on C3 and C2, our data raise questions about the implication of this protease in complement activation.

Controlled ovarian stimulation and ultrasound guided follicular aspiration in the baboon (Papio cynocephalus anubis)

The objective of this study was to investigate whether baboon females respond to an ovarian stimulation protocol incorporating pituitary suppression with a GnRH agonist (GnRHa) and highly purified human FSH (hphFSH) with follicular development and oocyte maturation. An ovulation induction protocol was applied to 5 adult female baboons with a history of regular menstrual cycles (33-34 days). A long-acting GnRHa implant containing goserelin acetate was placed s.c. on days 22-24 of their menstrual cycle. Daily hphFSH (75 IU im) treatments were started approximately 10 days following menses. When the majority of the follicles were > or = 5 mm in diameter and the E2 levels had reached a maximum, hCG (2000 IU i.m.) was administered to induce final maturation of the oocytes and ovulation. 30 to 34 h after hCG administration, transabdominal follicular aspiration was performed using a variable frequency transvaginal transducer with ultrasound. A total of 71 oocytes were collected (average: 17). 91% of the oocytes were morphologically normal indicating that they were appropriate for in vitro insemination.

Importance of assisted reproductive technologies in the conservation of wild, rare or indigenous ungulates: review article

Biodiversity is increasingly threatened by intensive agriculture, environmental pollution, extinction of natural habitats and several other factors. Several mammalian species including ungulates have disappeared or are threatened by extinction. However, ungulates play an important role both in the ecosystem and in the economy. In general, species or breeds are considered endangered if their population does not exceed 1,000 individuals. In these cases conservation programmes should be initiated in order to maintain or even increase their number. This review deals with the possibilities and limitations of assisted reproductive technologies (ART) in the conservation of ecologically valuable wild, rare and indigenous ungulates. The methods discussed here are artificial insemination, cryopreservation of semen and embryos, embryo recovery and transfer, in vitro production of embryos, as well as micromanipulation techniques including sperm injection, assisted hatching and cloning. Some of these procedures are already being exploited in the breeding of farm ungulates, but more basic information about the reproductive patterns of wild, rare and indigenous animal species is needed before the routine use of ARTs.

Interaction properties of human mannan-binding lectin (MBL)-associated serine proteases-1 and -2, MBL-associated protein 19, and MBL

The mannan-binding lectin (MBL) activation pathway of complement plays an important role in the innate immune defense against pathogenic microorganisms. In human serum, two MBL-associated serine proteases (MASP-1, MASP-2) and MBL-associated protein 19 (MAp19) were found to be associated with MBL. With a view to investigate the interaction properties of these proteins, human MASP-1, MASP-2, MAp19, as well as the N-terminal complement subcomponents C1r/C1s, Uegf, and bone morphogenetic protein-1-epidermal growth factor (CUB-EGF) segments of MASP-1 and MASP-2, were expressed in insect or human kidney cells, and MBL was isolated from human serum. Sedimentation velocity analysis indicated that the MASP-1 and MASP-2 CUB-EGF segments and the homologous protein MAp19 all behaved as homodimers (2.8-3.2 S) in the presence of Ca(2+). Although the latter two dimers were not dissociated by EDTA, their physical properties were affected. In contrast, the MASP-1 CUB-EGF homodimer was not sensitive to EDTA. The three proteins and full-length MASP-1 and MASP-2 showed no interaction with each other as judged by gel filtration and surface plasmon resonance spectroscopy. Using the latter technique, MASP-1, MASP-2, their CUB-EGF segments, and MAp19 were each shown to bind to immobilized MBL, with K:(D) values of 0.8 nM (MASP-2), 1.4 nM (MASP-1), 13.0 nM (MAp19 and MASP-2 CUB-EGF), and 25.7 nM (MASP-1 CUB-EGF). The binding was Ca(2+)-dependent and fully sensitive to EDTA in all cases. These data indicate that MASP-1, MASP-2, and MAp19 each associate as homodimers, and individually form Ca(2+)-dependent complexes with MBL through the CUB-EGF pair of each protein. This suggests that distinct MBL/MASP complexes may be involved in the activation or regulation of the MBL pathway.

The cleavage of two C1s subunits by a single active C1r reveals substantial flexibility of the C1s-C1r-C1r-C1s tetramer in the C1 complex

The activation of the C1s-C1r-C1r-C1s tetramer in the C1 complex, which involves the cleavage of an Arg-Ile bond in the catalytic domains of the subcomponents, is a two-step process. First, the autolytic activation of C1r takes place, then activated C1r cleaves zymogen C1s. The Arg463Gln mutant of C1r (C1rQI) is stabilized in the zymogen form. This mutant was used to form a C1q-(C1s-C1rQI-C1r-C1s) heteropentamer to study the relative position of the C1r and C1s subunits in the C1 complex. After triggering the C1 by IgG-Sepharose, both C1s subunits are cleaved by the single proteolytically active C1r subunit in the C1s-C1rQI-C1r-C1s tetramer. This finding indicates that the tetramer is flexible enough to adopt different conformations within the C1 complex during the activation process, enabling the single active C1r to cleave both C1s, the neighboring and the sequentially distant one.

Ovarian consequences of low dose peroral Fusarium (T-2) toxin in a ewe and heifer model

The effect of low dose peroral Fusarium produced T-2 toxin intake upon the ovarian function was evaluated in ewes (n = 30; Trial 1) and heifers (n = 7; Trial 2). Half of the ewes and all of the heifers were fed rich, acidosis-inducing concentrate. The 30 ewes were divided into 6 groups of 5 animals each. They were given 0, 0.3 or 0.9 mg/day (0, 5 or 15 ug/kg) purified T-2 toxin per os for 21 days (3x2 factorial design). Four of the 7 heifers were fed 9 mg/day (25 ug/kg) of the same purified T-2 toxin for 20 days while 3 remained untreated. The estrus cycles in all animals were synchronized prior to the trials and the T-2 exposure was started in the mid-luteal phase. The acidic condition in the rumen was estimated by the determination of urinary net acid-base excretion. The ovarian activity was followed with blood sampling for progesterone on alternate days (Trial 1) or with ultrasonography and sampling for progesterone daily (Trial 2). All of the heifers and concentrate-fed ewes showed a compensated acidosis, during first two thirds of T-2 exposure. In Trial 1, ovarian malfunction manifested as lower P4 peak concentration in the midluteal phase, shortening of the CL lifespan and prolonged follicular phases. These malfunctions were detected in 3 and 3 ewes fed concentrate and 0.3 mg and 0.9 mg T-2 toxin. Lower P4 peak concentration was observed in 1 ewe fed regular diet and 0.9 mg T-2 toxin. None of the control and acidotic groups (0 mg T-2), or ewes fed regular diet with 0.3 mg T-2 showed any ovarian malfunction. In Trial 2, after PGF2, administration the ovulation occured later and the plasma progesterone level remained low (< 3 nmol/l) for a longer period in T-2 treated heifers, than their untreated control mates (5.0+/-0.7 vs 3.7+/-0.5 d, P<0.05 and 8.3+/-0.4 vs 6.3+/-0.9 d, P<0.01, respectively). These results show that the peroral T-2 intake can significantly retard the folliculus maturation and ovulation and perhaps the subsequent luteinisation also in ruminants kept on concentrate-rich diet.

Analysis of papillomavirus consensus L1 gene in a closed colony of baboons (Papio anubis)

OBJECTIVE

The purpose of this study was to analyze cervical specimens and semen from a closed colony of baboons for the presence of the papillomavirus consensus L1 gene.

STUDY DESIGN

Cervical swabs were collected from lightly anesthetized female baboons. Semen was collected from a male baboon by standard electroejaculation techniques. Deoxyribonucleic acid was extracted from the cells by two different methods and analyzed by polymerase chain reaction targeting the L1 consensus gene common for >25 genital papillomaviruses.

RESULTS

Analyses of the polymerase chain reaction-amplified products did not reveal bands for the papillomavirus in either the cervical specimens or the semen.

CONCLUSIONS

The hypothesis of a linkage between primates with papillomavirus as a common factor is not supported by the results of this study. This information is also important in assisting clinicians in setting up specific pathogen-free colonies of baboons.

Economical and ecological importance of indigenous livestock and the application of assisted reroduction to their preservation

Among the many mammalian species that are threatened as the result of habitat destruction are numerous species of rare or little-known native livestock that possess features that render them ideally adapted to their environment. Because of the vital and valuable role many of these species play both to the ecology and economy of their native countries, attention is being directed towards initiating breeding programs that might insure their continued survival. This review introduces and highlights the importance of some of these indigenous species and outlines efforts currently underway to apply assisted reproductive technologies to their conservation.

Vitrification of mouse embryos in two cryoprotectant solutions

The objective of this study was to compare the efficiency of 2 media on the vitrification of mouse compacted morulae, early blastocysts and expanded blastocysts after equilibration at room temperature of 4 degrees C. Embryos were equilibrated for 10 min in either 25% VS3 (Rall Equilibration Medium, REM) or 10% glycerol + 20% propylene glycol (Massip Equilibration Medium, MEM) in DPBS at 20 degrees C or 4 degrees C. For vitrification either 100% VS3 (Rall Vitrification Medium, RVM) or 25% glycerol + 25% propylene glycol (Massip Vitrification Medium, MVM) in DPBS was used. Embryos equilibrated at room temperature were loaded in 20 microL of vitrification media into 250 microL straws and then immediately (30 sec) plunged into liquid nitrogen (LN2). After equilibration at 4 degrees C the embryos were put into straws with 20 microL of precooled vitrification medium, and after 20 min at 4 degrees C they were plunged into LN2. Embryos from both groups were thawed in a 20 degrees C water bath for 20 sec, transferred to 1.0 M sucrose in DPBS for 5 min and then cultured for 24 to 48 h in Whitten's medium at 37 degrees C in 5% CO2 in air. In the groups of embryos prepared for vitrification at room temperature the survival rate of compact morulae vitrified in RVM was higher than those vitrified in MVM (65/70, 93% vs 49/74, 66%; P < 0.01). No difference was found in the survival rate of early blastocysts and expanded blastocysts vitrified in RVM or MVM (30/83, 36% vs 25/75, 33% and 4/66, 6% vs 4/76, 5%). No difference was found between the survival rate of compact morulae after equilibration with RVM or MVM at 4 degrees C (62/75, 83% vs 52/74, 70%). Both the early blastocysts and expanded blastocysts equilibrated at 4 degrees C MVM yielded a higher survival rate than RVM (28/74, 38% and 40/70, 57% vs 4/75, 5% and 4/77, 5%; P < 0.01). We conclude that, of the 3 developmental stages, compact morulae withstand the vitrification process best, and reduction of the temperature prior to plunging into LN2 is not required. A 10-fold increase in the survival rate of expanded blastocysts can be achieved using low temperature equilibration (4 degrees C) and MVM.

One active C1r subunit is sufficient for the activity of the complement C1 complex: stabilization of C1r in the zymogen form by point mutations

The binding of C1 (the first component of complement) to immune complexes leads to the autoactivation of C1r through the cleavage of the Arg463-Ile464 bond in the catalytic domain. Spontaneous activation of C1r (and C1) also occurs in the fluid phase, preventing the characterization of the zymogen form of C1r. To overcome this difficulty, the zymogen form of human C1r was stabilized by mutating the Arg in the Arg463-Ile464 bond to Gln. This mutant was designated as mutant QI. Recombinant C1r (wild type (wt) or mutant) was expressed in insect cells using serum-free medium in functionally pure form; therefore, the cell culture supernatant was suitable to reconstruct C1 for the hemolytic assay. Mutant QI was a stable, nonactivable zymogen and showed no hemolytic activity in reconstituted C1. However, this stable zymogen C1r mutant could form an active mixed dimer with the wt C1r, indicating that one active C1r subunit in the C1 complex is sufficient for the full activity of the entire complex. Our experiments also showed that the exchange of C1r monomers between the C1r dimers is completed in less than 16 h even at pH 7 and 4 degrees C. Two other mutants were also constructed by changing Arg463 to Lys, or Ile464 to Phe, and were designated as mutants KI and RF, respectively. Although these substitutions did increase the stability of the proenzyme in the cell culture supernatant, the mutant proteins retained their ability to autoactivate, and both had a wt-like hemolytic activity.

Isolation of human alpha 2HS-glycoprotein synthesized by Sf9 cells

The human alpha 2HS-glycoprotein is a negative acute phase protein synthesized by hepatocytes. Because of its fragility and the difficulty of its purification, we used recombinant DNA techniques to produce the protein in order to investigate its biological effects. The cDNA coding for the whole alpha 2HS-glycoprotein from human liver library had been cloned into the baculovirus expression vector system using the pVL 1392 transfer vector and Sf9 cells. The recombinant protein was synthesized in the Sf9 cells and was isolated on a hydroxiapatite column from the culture medium. Western blot analysis indicated that the cells synthesized large quantities of the recombinant human protein. The molecular mass of the recombinant AHSG was the same as that of the protein in human plasma but was slightly lower than that of AHSG in the cell culture supernatants of HepG2 and higher than that of AHSG from Hep3B cell cultures, respectively.

The effect of quick-freezing in ethylene glycol on morphological survival and in vitro development of mouse embryos frozen at different preimplantation stages

This study was conducted to examine the effect of a quick-freezing protocol on morphological survival and in vitro development of mouse embryos cryopreserved in ethylene glycol (EG) at different preimplantation stages. One-cell embryos were harvested from 6-to 8-wk-old CB6F1 superovulated mice, 20 to 23 h after pairing with males of the same strain and hCG injection. The embryos were cultured in human tubal fluid (HTF) containing 4 mg/ml BSA under mineral oil at 37 degrees C in 5% CO(2) plus 95% room air at maximal humidity. Twenty-four to 96 h after collection, the embryos were removed from culture and frozen at the 2 cell, 4 to 8-cell, compact morula, early blastocyst, expanding blastocyst and expanded blastocyst stages. To perform the quick-freeze procedure, embryos were equilibrated in Dulbecco's phosphate buffered saline (DPBS) + 10 % fetal bovine serum (FBS) + 0.25 M sucrose + 3 M ethylene glycol (freeze medium) for 20 min at room temperature (22 to 26 degrees C) and loaded in a single column of freeze medium into 0.25-ml straws (4 to 5 embryos per straw). The straws were held in liquid nitrogen vapor for 2 min and immersed in liquid nitrogen. Embryos were thawed by gentle agitation in a 37 degrees C water bath for 20 sec and transferred to DPBS + 10 % FBS + 0.5 M sucrose (re-hydration medium) for 10 min at room temperature, rinsed 2 times in HTF plus 4 mg/ml BSA and then cultured for 24 to 96 h. Survival of embryos was based on their general morphological appearance after thawing and their ability to continue development upon subsequent culture in vitro. Survival of blastocysts after thawing also required expansion or reexpansion of the blastocoel after several hours in culture. Significant differences were found in the survival and development of mouse embryos at different developmental stages quick-frozen in ethylene glycol and sucrose: 2-cell embryos 43/84 (51%), 4 to 8-cell embryos 44/94 (47%), morulae and early blastocysts 56/70 (80%; P</=0.05), expanding and expanded blastocysts 10/59 (17%; P</=0.05). Our data indicate that the developmental stage in which mouse embryos are subjected to this quick-freeze protocol affects survival and development in vitro and that most (80%) morula and early blastocyst stage embryos survive the procedure.

Functional effects of domain deletions in a multidomain serine protease, C1r

The C1r subcomponent of the first component of complement is a complex, multidomain glycoprotein containing five regulatory or binding modules in addition to the serine protease domain. To reveal the functional role of the N-terminal regulatory domains, two deletion mutants of C1r were constructed. One mutant comprises the N-terminal half of domain I joined to the second half of the highly homologous domain III, resulting in one chimeric domain in the N-terminal region, instead of domains I-III. In the second mutant most of the N-terminal portion of domain I was deleted. Both deletion mutants were expressed in the baculovirus-insect cell expression system with yields typical of wild type C1r. Both mutants maintained the ability of the wild type C1r to dimerize. The folding and secretion of the recombinant proteins was not affected by these deletions, and C1-inhibitor binding was not impaired. The stability of the zymogen was significantly decreased however, indicating that the N-terminal region of the C1r molecule contains essential elements involved in the control of activation of the serine protease module. Tetramer formation with C1s in the presence of Ca2+ was abolished by both deletions. We suggest that the first domain of C1r is essential for tetramer formation, since the deletion of domain I from C1r impairs this interaction.

Rapid freezing of mouse embryos in ethylene glycol at different preimplantation stages

The objectives of this study were to examine the effects of a rapid freezing protocol on the survival and in vitro development of mouse embryos cryopreserved in ethylene glycol (EG) at different preimplantation stages, and secondly, to investigate the effect of exposure to 3.0 M EG with 0.25 M sucrose on the survival and in vitro development of mouse embryos without freezing at different developmental stages. To perform the rapid freezing procedure, embryos were equilibrated in Dulbecco's phosphate buffered saline (DPBS) containing 3.0 M EG and 0.25 M sucrose (freeze medium) for 20 min and loaded into 250 microliters straws in a single column of freeze medium. The straws were held in liquid nitrogen (LN2) vapour for 2 min and immersed into LN2. Embryos were thawed in a 37 degrees C water bath for 20 sec and transferred to DPBS supplemented with 0.5 M sucrose (rehydration medium) for 10 min and cultured for 24 to 96 h in HTF (Human Tubal Fluid) plus 4 mg/ml BSA (Bovine Serum Albumin). Significant differences were found in the survival and development of mouse embryos at different developmental stages rapid frozen in EG and sucrose: two cell 43/84 (51%), 4-8 cell 44/94 (47%), morula and early blastocyst 56/70 (80%), expanding and expanded blastocysts 10/59 (17% (p < 0.05). These data indicate that the developmental stage in which mouse embryos are subjected to this quick freeze protocol affects survival and development in vitro and the majority (80%) of morula and early blastocyst stage embryos survive the procedure. No significant differences were observed in the in vitro developmental capacity of embryos at different developmental stages after treatment with high concentrations (3.0 M) of EG solution without freezing. Further investigations are underway to better understand the reasons for different survival rates of embryos frozen at different developmental stages using the present procedure.

Protein engineering studies on C1r and C1s

1. C1r and C1s cDNAs were placed downstream the strong polyhedrin promoter in the Autographa californica nuclear polyhedrosis virus and the recombinant proteins were expressed in insect cells, in biologically active form. The yield of expression is high enough to get recombinant components for chemical and functional studies (5 micrograms/ml cell culture supernatant). 2. The biological activity and the post-translational modifications of the recombinant subcomponents were checked. The rC1r and rC1s proved to be biologically active in the hemolytic assay, although their glycosylations were different compared to that of the serum proteins. The insect cells are able to beta-hydroxylate the Asn residue of the EGF domain in the C1r but with a low efficiency. It is clear now, that this post-translational modification does not play a role in the Ca2+ dependent C1r-C1s interaction. 3. Two deletion mutants of C1r cDNA were constructed in order to clarify the role of domain I and II. The results show that both, domain I, and II are absolutely necessary for the tetramer formation and both have a regulatory role in the autoactivation. The autoactivation of the mutants is accelerated significantly. 4. Hybrid cDNA constructions were also made, and one of them was expressed. In the C1s alpha R hybrid the C1s alpha part cannot dimerize in presence of Ca2+, but it can form a tetramer with C1r2, that can bind to C1q. This observation indicates that the function of the C1s alpha part in the hybrid is modulated by the C1r part (gamma B) of the molecule. 5. In order to control the autoactivation process point mutant cDNAs were constructed through altering the Arg-Ile bond in the catalytic domain of the C1r. The Gln-Ile construction is a stable zymogen while the Arg-Phe mutant has a lower rate of autoactivation. These results do justify our approach of using domain-domain interchange, domain deletion and point mutations in combination, to reveal the structural background of C1 function at intramolecular level.