Reduction in tolerance to progressive hypoxia in the central stoneroller minnow following sublethal exposure to phenol

Acute exposure of the central stoneroller minnow to sublethal levels of phenol was found to decrease the ability of this species to tolerate hypoxic conditions as indicated by the dissolved oxygen (DO) concentration at which loss of equilibrium occurred. For fishes acclimated at 7.5 °C, loss of equilibrium occurred at progressively higher DO levels as the phenol exposure concentration was increased from 0 to 12 mg phenol L^?1. Mean DO concentrations at which loss of equilibrium occurred ranged from 2.33 ± 0.10 mg O₂ L^?1. for the control group (0 mg phenol L^?1. to 2.76 ± 0.14 mg O₂ L^?1. (at 12 mg phenol L^?1. Loss of equilibrium also occurred at progressively higher DO levels in fish acclimated at 23 °C, but only after an initial decrease among the 6 mg phenol L^?1. test fish in the loss of equilibrium DO concentration. At 23 °C, loss of equilibrium occurred at DO levels ranging from 1.3 ± 0.09 mg O₂ L^?1. (6 mg phenol L^?1. to 2.33 ± 0.16 mg O₂ L^?1. (12 mg phenol L^?1. These data indicate that acute exposures to sublethal levels of phenol can have significant effects on the ability of the stoneroller minnow to tolerate conditions of low DO, and the results agree with the previously reported relationship between phenol toxicity and DO levels.     

A stem cell molecular signature

Mechanisms regulating self-renewal and cell fate decisions in mammalian stem cells are poorly understood. We determined global gene expression profiles for mouse and human hematopoietic stem cells and other stages of the hematopoietic hierarchy. Murine and human hematopoietic stem cells share a number of expressed gene products, which define key conserved regulatory pathways in this developmental system. Moreover, in the mouse, a portion of the genetic program of hematopoietic stem cells is shared with embryonic and neural stem cells. This overlapping set of gene products represents a molecular signature of stem cells.     

Forest policy in aroused society: Ukrainian post-Orange Revolution challenges

With the collapse of the communist regime the market changes were introduced in Ukraine, as in other Central and Eastern European Countries, including forestry sector. Reform was not as radical as in other sectors of economy, nor in the forestry sector as in some other countries of region. Ukraine is involved in international forest policy dialogue, particularly Intergovernmental and Pan-European processes of the forest sector development on the principles of sustainability, but implementation of international agreements needs to be sounder in practice.This paper discusses the current situation in forest sector and achievements and failures in economic, environmental, and social aspects of forest sector development. Policy and institutional mechanisms to develop the sustainable forest management (SFM) approaches are discussed. We analyze preconditions for institutional building (legislature, institutions, policy actors) looking at both the existing potential and the constraints in the realization of urgent tasks that arise in the economy in a period of transition. Specific attention is given to the national forest policy conception and forest sector development prospects.     

Stem cells and their niches

A constellation of intrinsic and extrinsic cellular mechanisms regulates the balance of self-renewal and differentiation in all stem cells. Stem cells, their progeny, and elements of their microenvironment make up an anatomical structure that coordinates normal homeostatic production of functional mature cells. Here we discuss the stem cell niche concept, highlight recent progress, and identify important unanswered questions. We focus on three mammalian stem cell systems where large numbers of mature cells must be continuously produced throughout adult life: intestinal epithelium, epidermal structures, and bone marrow.