The ciliary marginal zone of the zebrafish retina: clonal and time-lapse analysis of a continuously growing tissue.

Clonal analysis is helping us understand the dynamics of cell replacement in homeostatic adult tissues (Simons and Clevers, 2011). Such an analysis, however, has not yet been achieved for continuously growing adult tissues, but is essential if we wish to understand the architecture of adult organs. The retinas of lower vertebrates grow throughout life from retinal stem cells (RSCs) and retinal progenitor cells (RPCs) at the rim of the retina, called the ciliary marginal zone (CMZ). Here, we show that RSCs reside in a niche at the extreme periphery of the CMZ and divide asymmetrically along a radial (peripheral to central) axis, leaving one daughter in the peripheral RSC niche and the other more central where it becomes an RPC. We also show that RPCs of the CMZ have clonal sizes and compositions that are statistically similar to progenitor cells of the embryonic retina and fit the same stochastic model of proliferation. These results link embryonic and postembryonic cell behaviour, and help to explain the constancy of tissue architecture that has been generated over a lifetime.This work was supported by a Wellcome Trust Senior Investigator Awards [100329/Z/12/Z to W.A.H.] and [098357/Z/12/Z to B.D.S].This is the final version of the article. It first appeared from The Company of Biologists via https://doi.org/10.1242/dev.13331

Учет материально-производственных запасов на примере ООО "Доминанта-мебель"

В данной работе рассматриваются теоретические основы и учет материальных затрат в ООО "Доминанта мебель". Даны рекомендации по совершенствованию учета и управлению материальными затратами.In this paper, we consider the theoretical basis and accounting of material costs in Dominanta Mebel. Recommendations are given for improving the accounting and management of material costs in the enterprise

A chronic moderate methionine administration induced hyperhomocysteinemia associated with cardiovascular disease phenotype in the sand rat Psammomys obesus

Introduction. Cardiovascular diseases were defined as coronary artery, cerebrovascular, or peripheral arterial disease. Hyperhomocysteinemia (Hhcy) is an independent risk factor of cardiovascular diseases, including atherosclerosis. Our previous studies demonstrated the involvement of Hhcy in cardiovascular remodeling in the sand rat Psammomys obesus. Material and methods. An experimental Hhcy was induced, in the sand rat Psammomys obesus, by a daily intraperitoneal injection of 70 mg/kg of methionine for a total duration of 6 months. The impact of Hhcy on the cellular and matrix structures of the heart, aorta and liver was analyzed using histological techniques. Additionally we treatedprimary cultures of aortic smooth muscle cells (SMCs) with high concentration of methionine to investigate the effects of methionine at the cellular level. Results. A moderate Hhcy induced a significant increase in the extracellular matrix components particularly collagens which accumulated in the interstitial and perivascular spaces in the studied organs indicating a developing fibrosis. A liver steatosis was also observed following methionine treatment. Further analysis of the aorta showed that Hhcy also induced vascular alterations including SMCs reorientation and proliferation associated with aneurysm formation. Conclusions. Our results show for the first time that Hhcy can induce a cardiovascular and liver diseases phenotype in Psammomys obesus, a species previously shown to be a good model for the studies of diabetes and other metabolism-related pathologies