Medical Research Council

About: Medical Research Council is a government organization based out in London, United Kingdom. It is known for research contribution in the topics: Population & Malaria. The organization has 16430 authors who have published 19150 publications receiving 1475494 citations.

Osteal tissue macrophages are intercalated throughout human and mouse bone lining tissues and regulate osteoblast function in vitro and in vivo.

Abstract: Resident macrophages are an integral component of many tissues and are important in homeostasis and repair. This study examines the contribution of resident tissue macrophages to bone physiology. Using immunohistochemistry, we showed that a discrete population of resident macrophages, OsteoMacs, was intercalated throughout murine and human osteal tissues. OsteoMacs were distributed among other bone lining cells within both endosteum and periosteum. Furthermore, OsteoMacs were coisolated with osteoblasts in murine bone explant and calvarial preparations. OsteoMacs made up 15.9% of calvarial preparations and persisted throughout standard osteoblast differentiation cultures. Contrary to previous studies, we showed that it was OsteoMacs and not osteoblasts within these preparations that responded to pathophysiological concentrations of LPS by secreting TNF. Removal of OsteoMacs from calvarial cultures significantly decreased osteocalcin mRNA induction and osteoblast mineralization in vitro. In a Transwell coculture system of enriched osteoblasts and macrophages, we demonstrated that macrophages were required for efficient osteoblast mineralization in response to the physiological remodeling stimulus, elevated extracellular calcium. Notably, OsteoMacs were closely associated with areas of bone modeling in situ, forming a distinctive canopy structure covering >75% of mature osteoblasts on diaphyseal endosteal surfaces in young growing mice. Depletion of OsteoMacs in vivo using the macrophage-Fas-induced apoptosis (MAFIA) mouse caused complete loss of osteoblast bone-forming surface at this modeling site. Overall, we have demonstrated that OsteoMacs are an integral component of bone tissues and play a novel role in bone homeostasis through regulating osteoblast function. These observations implicate OsteoMacs, in addition to osteoclasts and osteoblasts, as principal participants in bone dynamics.

Sequencing of the sea lamprey (Petromyzon marinus) genome provides insights into vertebrate evolution

Abstract: Lampreys are representatives of an ancient vertebrate lineage that diverged from our own ∼500 million years ago. By virtue of this deeply shared ancestry, the sea lamprey (P. marinus) genome is uniquely poised to provide insight into the ancestry of vertebrate genomes and the underlying principles of vertebrate biology. Here, we present the first lamprey whole-genome sequence and assembly. We note challenges faced owing to its high content of repetitive elements and GC bases, as well as the absence of broad-scale sequence information from closely related species. Analyses of the assembly indicate that two whole-genome duplications likely occurred before the divergence of ancestral lamprey and gnathostome lineages. Moreover, the results help define key evolutionary events within vertebrate lineages, including the origin of myelin-associated proteins and the development of appendages. The lamprey genome provides an important resource for reconstructing vertebrate origins and the evolutionary events that have shaped the genomes of extant organisms.

Seasonal breeding:nature's contraceptive.

Abstract: Publisher Summary This chapter focuses on the seasonal control of fertility. It discusses two aspects in detail—the way in which changes in the secretion of luteinizing hormone-releasing hormone by the hypothalamus controls the activity of the pituitary and testis, and the way changes in day length influence the activity of the hypothalamus. The downstream events evoked by the hypothalamus are relatively easy to understand, whereas the mechanisms involved in the photoperiodic control are very complex and largely unresolved. While seasonal changes in temperature, rainfall, and food availability are the factors of the environment that dictate survival of adults and young—and are thus ultimately responsible for dictating the timing of the birth season—these are not necessarily the factors used as cues by the animals to regulate their reproductive endocrinology. This is because it is necessary to anticipate the timing of birth by dictating the timing of conception, as the duration of gestation in mammals is usually fixed. As accurate timing of conception is important, animals tend to become reliant on cues from the environment, which are the best predictors of the time of year. The seasonal cycle highlights the seasonal changes in daylight length, rutting behavior, testicular diameter, sexual skin flush, and concentrations of plasma follicle-stimulating hormone, prolactin, and testosterone in a group of rams throughout the year.