For 10,000 years pigs and humans have shared a close and complex relationship. From domestication to modern breeding practices, humans have shaped the genomes of domestic pigs. Here we present the assembly and analysis of the genome sequence of a female domestic Duroc pig (Sus scrofa) and a comparison with the genomes of wild and domestic pigs from Europe and Asia. Wild pigs emerged in South East Asia and subsequently spread across Eurasia. Our results reveal a deep phylogenetic split between European and Asian wild boars ~1 million years ago, and a selective sweep analysis indicates selection on genes involved in RNA processing and regulation. Genes associated with immune response and olfaction exhibit fast evolution. Pigs have the largest repertoire of functional olfactory receptor genes, reflecting the importance of smell in this scavenging animal. The pig genome sequence provides an important resource for further improvements of this important livestock species, and our identification of many putative disease-causing variants extends the potential of the pig as a biomedical model.

Bacteria from the genus Streptomyces are among the most complex of all prokaryotes; not only do they grow as a complex mycelium, they also differentiate to form aerial hyphae before developing further to form spore chains. This developmental heterogeneity of streptomycete microcolonies makes studying the dynamic processes that contribute to growth and development a challenging procedure. As a result, in order to study the mechanisms that underpin streptomycete growth, we have developed a system for studying hyphal extension, protein trafficking, and sporulation by time-lapse microscopy. Through the use of time-lapse microscopy we have demonstrated that Streptomyces coelicolor germ tubes undergo a temporary arrest in their growth when in close proximity to sibling extension sites. Following germination, in this system, hyphae extended at a rate of ϳ20 m h ؊1 , which was not significantly different from the rate at which the apical ring of the cytokinetic protein FtsZ progressed along extending hyphae through a spiraling movement. Although we were able to generate movies for streptomycete sporulation, we were unable to do so for either the erection of aerial hyphae or the early stages of sporulation. Despite this, it was possible to demonstrate an arrest of aerial hyphal development that we suggest is through the depolymerization of FtsZ-enhanced green fluorescent protein (GFP). Consequently, the imaging system reported here provides a system that allows the dynamic movement of GFP-tagged proteins involved in growth and development of S. coelicolor to be tracked and their role in cytokinesis to be characterized during the streptomycete life cycle.Fluorescence microscopy has revolutionized our understanding of the bacterial cell and provided new opportunities to investigate the behavior of cell division proteins and chromosome dynamics in bacteria (25). Central to this research is the application of time-lapse microscopy to study bacterial cell division, which has revealed the complexity with which bacteria coordinate cellular growth and division. For example, the rodshaped bacteria Escherichia coli and Bacillus subtilis incorporate new peptidoglycan into their cell wall along their lateral walls, while coccoid bacteria such as Staphylococcus aureus do so at mid-cell (4). Actinobacteria, such as Corynebacterium and members of the mycelial, antibiotic-producing genus Streptomyces, incorporate peptidoglycan at the cell poles (4). In the case of streptomycetes, this allows them to adopt a hyphal growth strategy through peptidoglycan incorporation at the hyphal tip (9). This is ideally suited to the colonization of their particulate habitat, the soil, through the generation of a mycelium that permits nutrients to be transported from a nutrient reservoir to the actively growing tip. As such, streptomycetes represent a group of organisms that grow in a fashion distinct from other, better understood bacteria. The knowledge base associated with morphological and physiological differentiation in the model organism Streptomy...

We observed movies of replisome trafficking during Streptomyces coelicolor growth. A replisome(s) in the spore served as a replication center(s) until hyphae reached a certain length, when a tip-proximal replisome formed and moved at a fixed distance behind the tip at a speed equivalent to the extension rate of the tip.Members of the bacterial genus Streptomyces exhibit mycelial growth and sporulation that are reminiscent of those of filamentous fungi. Spores germinate to form germ tubes (7,18), which extend to elongated hyphae through peptidoglycan incorporation at the hyphal tip (2, 4). Eventually, a mycelium is formed by branch emergence from the lateral hyphal walls. Incorporation of new cell wall material at the hyphal tip and branch points is, either directly or indirectly, dependent on the essential protein DivIVA (3). Typical cell division does not occur during vegetative growth, and elongated, multigenomic compartments are delimited by occasionally spaced septa. In contrast to most other bacteria, in this genus many genes required for cell division are inessential for vegetative growth and are required only during sporulation (14). The chromosomes in the vegetative hyphae seem to remain uncondensed and do not undergo typical segregation. Early studies using pulse-labeling revealed that hyphae did not show any region of preferential incorporation of the label and that replicating nucleoids were evenly distributed along the hyphae (12, 13). This indicates that DNA replication does not depend on nucleoid location; the corollary of this is that mechanisms must exist to allow chromosomes to populate the extending hypha. However, Yang and Losick (19) were unable to find any evidence that DNA replication activity was concentrated at the apex. Further studies using a functional DnaN-enhanced green fluorescent protein (EGFP) fusion demonstrated that DNA replication takes place in both apical and subapical compartments of Streptomyces coelicolor vegetative hyphae (17). Moreover, replication is asynchronous, and only selected chromosomes undergo replication at any given time (17). Recently, a new method for monitoring Streptomyces hyphal growth in real time using time-lapse microscopy was established by Jyothikumar et al. (11). It showed that, following germination, hyphal extension occurred at about 20 m h Ϫ1 when grown on mannitol-supplemented minimal medium at 30°C. Here, we present the results obtained by application of this method (11) to study replisome dynamics in vegetative mycelium. Captured images were processed using IPlabs 3.7 image processing software (BD Biosciences Bioimaging, Rockville, MD). Eleven