It is generally known that the culture for mycoplasma is time-consuming and a variety of nutrients are needed in the culture medium.  This brings a lot of difficulties to mycoplasma research and application, including Mycoplasma mycoides subsp. capri (Mmc).  Furthermore, little research on the characteristics of Mmc metabolism has been reported.  In this study, Mmc PG3 strain cultures were investigated for dynamic gene expression.  Culture samples were harvested during logarithmic phase (PG3-1), stationary phase (PG3-2), decline phase (PG3-3) and late decline phase (PG3-4).  Twelve RNA samples (three replicates for each of the four growth stages considered) from these cultures were collected and sequenced.  Paired comparison between consecutive growth phases in the four growth stages showed 45 significant differentially expressed genes (P<0.01) were linked to PG3 metabolism.  The enzymes these genes coded were mainly involved in ATP synthase, pyrimidine metabolism, nicotinate and nicotinamide metabolism, arginine and proline metabolism.  Among these, cytidylate kinase, fructose 1,6-bisphosphate aldolases Class II, nicotinate-nucleotide adenylyltransferase and dihydrolipoamide dehydrogenase play a key role in Mmc metabolism.  These results provide a baseline to build our understanding of the metabolic pathway of Mmc.  

Domestic pigs are the second most important source of meat world-wide, and the genetic improvement of economic traits, such as meat production, growth, and disease resistance, is a critical point for efficient production in pigs.  Through conventional breeding and selection programs in pigs, which are painstakingly slow processes, some economic traits, such as growth and backfat, have been greatly improved over the past several decades.  However, the improvement of many polygenetic traits is still very slow and challenging to be improved by conventional breeding strategies.  The development of reproductive knowledge and a variety of techniques, including foreign gene transfer strategies, somatic cell nuclear transfer (SCNT) and particularly, recently developed nuclease-mediated genome editing tools, has provided efficient ways to produce genetically modified (GM) pigs for the dramatic improvement of economic traits.  In this review, we briefly discuss the progress of genomic markers used in pig breeding program, trace the history of genetic engineering, mainly focusing on the progress of recently developed genome editing tools, and summarize the GM pigs which have been generated to aim at the agricultural purposes.  We also discuss the specific challenges facing application of gene engineering in pig breeding, and future prospects.