Evaluation of risks associated with close environmental contact to swine that are transgenic for a bovine milk protein alpha-lactalbumin

Bovine alpha-lactalbumin;transgenic swine;transgenic;cohabitation;risk assessment;milk protein;swine;exposing non-tansgenic animals to transgenic animals

Mosley, Jonathon ; Hurley ; Walter L.

关键词: Bovine alpha-lactalbumin;    transgenic swine;    transgenic;    cohabitation;    risk assessment;    milk protein;    swine;    exposing non-tansgenic animals to transgenic animals;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/45406/Jonathon_Mosley.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Assessment of the risks associated with exposing non-transgenic animal populations to transgenic animals is important to the future contributions of transgenic livestock to society.Evaluation of the potential for transfer of a transgene (Tg) from livestock to a non-transgenic animal during parturition, mating, gestation, or lactation is the initial step in a risk assessment.We previously developed and characterized transgenic swine containing a mammary-specific transgene, bovine -lactalbumin, (B-LA) that results in increased milk production in sows.In this study, we wanted to determine whether B-LA is expressed in tissues of transgenic swine other than the lactating mammary gland and if the Tg DNA crosses into non-transgenic swine under various physiological and physical conditions.The specific aims addressed in this study were to determine (1) whether the Tg can be synthesized in any other tissues than the mammary gland of a transgenic sow; (2) whether the Tg can be transferred directly by physical association or contact; (3) whether the Tg can be transferred directly via mating; and (4) whether the Tg can be transferred directly during gestation, parturition, or lactation. This study included four separate experiments. In the first experiment 4 transgenic (T) and 6 non-transgenic (control; C) pigs were raised to 180, 220, 250 d of age, or 112 days post-breeding and then sacrificed for tissue collection.In the second experiment 41 T and 54 C pigs, of comparable age and weight, were housed together beginning at weaning (d 21) allowing for general contact that is normal in swine production.Pigs were housed together up to either 180, 220, or 250 d of age and then sacrificed for tissue collection.In the first and second experiments blood, brain, jejunum, kidney, liver, lung, mammary gland, muscle, ovary, sublingual salivary gland, skin, and spleen were collected. In the third experiment, the above samples, plus vaginal, cervical, uterine, oviductal, and ovarian tissues were collected from 34 C females on 2, 7, 90 or 112 d after mating to one of 10 T males, and along with above samples, penis, bulbourethral gland, urethra, testis, and epididymis tissues were collected from 12 C males 7 d after mating to one of 4 Tg females.The fourth experiment was divided into 3 sub-experiments:4a. fetuses were collected from 4 C sows bred to a C boar and 4 T sows bred to a C boar on d 112 of gestation and sacrificed fetuses were retrieved for tissue collection (n=56); 4b. Fifty-eight newborn piglets were removed from their birth dam before they were allowed to suckle and sacrificed for tissue collection, along with twenty-one C piglets were removed from their birth dam at the time of farrowing and before they were allowed to suckle and fostered to a lactating T sow (n=11) or to a lactating C sow (n=10).Piglets were allowed to suckle for 24 or 72 h and then sacrificed for tissue collection; 4c. nineteen C piglets were allowed to suckle their birth dam until d 3, and then were fostered to a lactating T sow (n= 11) or to a lactating C sow (n= 8).After cross-fostering the piglets were allowed to suckle for 72 or 168 h and then sacrificed for tissue collection.For each of the sub-experiments under experiment four, the tissues harvested were jejunum, liver, lung, muscle, and skin. For all experiments the presence of the Tg or its expression in tissues from C and T animals was determined by PCR analyses.Results indicated that the Tg is not expressed in tissues other than the mammary gland of a T lactating sow (n= 50 samples negative).The Tg was not identified in tissues from C animals after co-habitation for 180, 220, or 250 d (n=571 samples analyzed), nor from animals at 2, 7, 90, or 112 d post-mating (n =89, 166, 71, or 44 samples analyzed, respectively).At day 112 of gestation, all samples (n=127 samples analyzed) from non-transgenic piglets whose dam was transgenic were negative except for the outer placental membrane, which screened positive for the Tg, and which is consistent with the outer placental membrane being derived from the maternal tissue.Newborn piglets (n=58) all samples derived from mating C females to C males were all negative for the Tg. Of those samples taken from piglets derived from mating T females to C males 79 were positive and 52 were negative for Tg. Again, this is consistent with the T females being heterozygous for the Tg.Finally C piglets (n=21) that were cross-fostered before suckling (d 0) or were cross-fostered 3 d after birth and suckled Tg dams (n=19) were negative for the Tg in their tissues.These results strongly indicate that there is no horizontal transmission of the transgene between transgenic and non-transgenic pigs that occurs during rearing, mating, gestation, or lactation.