BackgroundMicroRNA (miRNA) are small non-coding RNA molecules critical for regulating cellular function, and are abundant in the maturing oocyte and developing embryo. MiRNA-21 (MIR21) has been shown to elicit posttranscriptional gene regulation in several tissues associated with rapid cell proliferation in addition to demonstrating anti-apoptotic features through interactions with PDCD4 mRNA and other targets. In many tissues, MIR21 interacts and suppresses PDCD4 due to the strong complementation between MIR21 and the PDCD4 3′UTR.MethodsThe objective of this project was to examine the relationship between MIR21 and PDCD4 expression in porcine oocytes during in vitro maturation and assess the impact of MIR21 inhibition during oocyte maturation on early embryo development. Additionally, we evaluated the effect of gonadotropins in maturation media and the presence of cumulus cells to determine their ability to contribute to MIR21 abundance in the oocyte during maturation.ResultsDuring in vitro maturation, expression of MIR21 increased approximately 6-fold in the oocyte and 25-fold in the cumulus cell. Temporally associated with this was the reduction of PDCD4 protein abundance in MII arrested oocytes compared with GV stage oocytes, although PDCD4 mRNA was not significantly different during this transition. Neither the presence of cumulus cells nor gonadotropins during in vitro maturation affected MIR21 abundance in those oocytes achieving MII arrest. However, inhibition of MIR21 activity during in vitro maturation using antisense MIR21 suppressed embryo development to the 4–8 cell stage following parthenogenetic activation.ConclusionsMIR21 is differentially expressed in the oocyte during meiotic maturation in the pig and inhibition of MIR21 during this process alters PDCD4 protein abundance suggesting posttranscriptional regulatory events involving MIR21 during oocyte maturation may impact subsequent embryonic development in the pig.

PurposeWe characterize the progression of retinopathy in Filial 1 (F1) progeny of a transgenic (Tg) founder miniswine exhibiting severe Pro23His (P23H) retinopathy.MethodsThe F1 TgP23H miniswine progeny were created by crossing TgP23H founder miniswine 53-1 with wild type (WT) inbred miniature swine. Scotopic (rod-driven) and photopic (cone-driven) retinal functions were evaluated in F1 TgP23H and WT littermates using full field electroretinograms (ffERGs) at 1, 2, 3, 6, 9, 12, and 18 months of age, as well as the Tg founder miniswine at 6 years of age. Miniswine were euthanized and their retinas processed for morphologic evaluation at the light and electron microscopic level. Retinal morphology of a 36-month-old Tg miniswine also was examined.ResultsWild type littermates reached mature scotopic and photopic retinal function by 3 months, while TgP23H miniswine showed abnormal scotopic ffERGs at the earliest time point, 1 month, and depressed photopic ffERGs after 2 months. Rod and cone photoreceptors (PR) exhibited morphologic abnormalities and dropout from the outer nuclear layer at 1 month, with only a monolayer of cone PR somata remaining after 2 months. The retinas showed progressive neural remodeling of the outer retina that included dendritic retraction of rod bipolar cells and glial seal formation by Müller cells. The TgP23H founder miniswine showed cone PR with relatively intact morphology exclusive to the area centralis.ConclusionsThe F1 Tg miniswine and the TgP23H founder miniswine exhibit similar retinopathy.Translational RelevanceTgP23H miniswine are a useful large-eye model to study pathogenesis and preservation cone PRs in humans with retinitis pigmentosa.

The objective of this study was to investigate an alternative feedstuff, Iowa-grown field peas, for finishing pigs. Field peas (winter, spring, and summer types) grown in southeast Iowa during 2005 and 2006 were sampled and analyzed for nutrient content. Overall, the peas averaged 86% DM, 2.8% ether extract, 5.7% crude fiber, 3% ash, 19.3% CP, 1.54% lysine, 0.20% methionine, 0.18% tryptophan, and 0.74% threonine. Finishing pigs, barrows (n = 64), were randomly assigned to 16 pens with four pigs each. There were four replications per treatment group. Each pen was assigned one of the four diets. The four diets were: 1) winter pea 30% of the total diet (by weight), 2) summer pea 30%, 3) spring pea 30%, and 4) corn-soybean meal as the control. The three pea diets contained corn but no soybean meal. Each of the four diets had 0.64% lysine based on calculated analysis.

The objective of this study was to investigate an alternative feedstuff, Iowa-grown field peas, for finishing pigs. Field peas (winter, spring, and summer types) grown in southeast Iowa during 2005 and 2006 were sampled and analyzed for nutrient content. Overall, the peas were 2.8% fat, 5.7% fiber, 3% ash, 19.3% protein, 1.5% lysine, 0.73% threonine 0.18% tryptophan, and 0.20% methionine. The spring peas were generally lower in fat and higher in essential amino acid content than the summer and winter peas. Finishing pigs, barrows (n = 64) were randomly assigned to pens with four pigs each. There were four replications per treatment group. Each pen was assigned one of the four diets. The four diets were: 1) winter pea 30% of the total diet (by weight), 2) summer pea 30%, 3) spring pea 30%, and 4) corn-soybean meal as the control. The three pea diets contained corn but no soybean meal. Each of the four diets had 0.64% lysine based on calculated analysis. Crystalline amino acids were added to the pea diets. The pigs started the experiment at 80 ± 2.5 kg live weight and were fed the experimental diets for 39 days. Pigs were weighed individually at the start, at 14-d intervals, and at the end of the experiment. At final weighing, backfat and loin muscle area was ultrasonically evaluated on each pig. There was no difference in final pig weight (123 ± 3 kg) in the four treatment groups. There were no treatment effects on average daily gain (ADG) (P = 0.22) across dietary treatments. Average daily feed intake (ADFI) was influenced by dietary treatments (P < 0.10). Pigs tended to consume less corn-soybean meal and spring pea diets than the winter and summer pea diets, with ADFI of 4.0, 3.8, 3.5, and 3.4 kg/d for winter, summer, spring, and the control diets, respectively. Feed:Gain (F:G) was not different among the treatment groups. Pigs fed winter peas had greater (P < 0.10) backfat (BF) than pigs fed spring peas or the control diet. Pigs fed summer peas were intermediate in BF and did not differ from the other treatments. There were no differences between dietary treatments for loin muscle area (LMA), although the pigs fed spring peas had numerically smaller loin muscle areas. There were no differences in the overall fat-free lean values (P > 0.10). In this study, the results showed no decrease in performance of finishing pigs at the inclusion rate of 30% field peas in a corn-based diet. The 30% field pea inclusion rate was enough to replace all the soybean meal and reduce the amount of corn in the diet. In the diets containing peas, synthetic amino acids, lysine, tryptophan, and threonine were added in the pea diets to avoid deficiencies. Because of their chemical composition, agronomic characteristic, and easy on-farm feeding, field peas are a potential crop to consider for Iowa pork production. Results from this study indicate, Iowa-grown field peas at 30% rate can replace all of the soybean meal and part of the corn in diets for finishing pigs with no negative effects on performance.

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