Michell Instruments (France)

The objective of this study was to compare the effectiveness of cryopreserving in vivo-produced alpaca embryos by slow freezing v. vitrification. The embryos were produced from 9 female alpacas at Fundo Mallkini, Puno, Peru, located at 4300m elevation. The donor alpacas were synchronized by induction to ovulate with an injection of gonadotropin-releasing hormone (0.0084mg of buserelin acetate) and natural mating with vasectomized males to male receptive donors (day of ovulation induction was considered Day 0). On Day 2, the donors were injected 700IU of eCG. On Day 7, the donors received an injection of prostaglandin F2α (0.25mg of cloprostenol) and were mated on Day 8 by fertile males (2 matings 12h apart: 0600 and 1800h). The embryos were collected at 5.5 days after fertile mating and were graded as per IETS recommendations; most of the embryos were already expanded and hatched blastocysts. Embryos were washed and maintained in holding medium (1L PBS+1g Glucose+36mg sodium pyruvate+0.4% BSA+50mg kanamycin monosulfate) at 23°C for up to 1h and distributed into 2 groups for either slow freezing for direct transfer (n=14 embryos) or vitrification (n=10 embryos). Slow freezing consisted of transfer into freezing medium (9mL of 1.5M ethylene glycol+1mL of 1.0M sucrose prepared in holding media) at 23°C, placing in 0.25-mL straws and subjected to freezing at a rate of −0.5°C/ minute to −35°C and then plunging into LN. Vitrification followed a procedure described for camel embryos whereby embryos were exposed to solutions containing increasing amounts of glycerol and ethylene glycol for fixed periods and were then loaded into an open pull straw and plunged directly into LN for storage. The cryopreserved embryos were transferred into adult alpacas at the Community of Suitucancha, Junin, Peru (1500km from the farm where the embryos were collected and cryopreserved, 4200m elevation). Embryos in the slow-freezing group were thawed in warm water at 37°C for 30s and loaded directly into the embryo transfer gun for direct transfer into 7 alpaca recipients (2 embryos per recipient). Vitrified embryos were warmed by removing the open pull straw from the LN and transferring the embryos to 2 warming solutions at 37°C with decreasing levels of vitricants and containing 0.5M galactose with a final incubation at room temperature in holding media and then transferred into 5 alpaca recipients (2 embryos per recipient). The embryos were transferred into synchronized recipients by transcervical nonsurgical method. Pregnancy diagnosis was made by transrectal ultrasound examination at 45 days post-transfer. The pregnancy rates in the slow-freezing and vitrification groups, respectively, were 2/7 (29%) and 0/5 (0%); the difference was not significant (P>0.05) based on Fisher’s exact test. Twin pregnancies were not detected. We consider the result with slow freezing very promising, as in previous trials we had less than 18% pregnancies. More trials with larger number of embryos per cryopreservation method are being programmed.

The inheritance of the two types of fleece, Suri and Huacaya, observed in Alpaca (Lama pacos L.) is still not clearly defined. The objective of this work is to investigate the patter of inheritance of these two phenotypes, throughout 588 Suri x Suri and 2126 Huacaya x Huacaya offspring. The single gene and the three two-phenotype epistatic models were tested in the 19 Suri x Suri segregating families. The single dominant gene hypothesis best fitted our segregation data and could be, therefore, accepted (Gt=20.276, P=0.378). The gene frequency of the recessive Huacaya allele was 0.295, being the frequency of the dominant Suri allele 0.705. The frequency of heterozygotes, estimated in the whole population and among dominant individuals, was 0.416 and 0.455, respectively, with a “carrier” Suri to Huacaya ratio of 4.780. In three Huacaya families, 3 Suri were born, as a result of a new dominant mutation on some germinal lines of Huacaya animals. The direct mutation rate can be estimated at 0.0014.

Summary: Since the bone marrow is now believed to be the source of many of the cells participating in immune reactions immunological function was tested in eleven patients with aplastic anaemia. Nine were lymphocytopenic and seven were monocytopenic. Various abnormalities were detected, the most common being failure to show intradermal hypersensitivity in six patients and failure to produce antibody to tetanus toxoid in six. Immunological impairment may be a factor in some of the clinical manifestations of aplastic anaemia.