The chloroplasts of internodal cells of Nitella are fixed to a stationary layer of cytoplasm whereas the nuclei and most of the cytoplasm stream along the longitudinal axis. Isolated internodal cells were maintained for several days with half the cell kept in the dark, the other half kept under continuous light. Photosynthetic activity of the cells was checked by placing the cell evenly illumin...

B cells undergo rapid cell division and affinity maturation in anatomically distinct sites in lymphoid organs called germinal centers (GCs). Homeostasis is maintained in part by B cell apoptosis. However, the precise contribution of apoptosis to GC biology and selection is not well defined. We developed apoptosis-indicator mice and used them to visualize, purify, and characterize dying GC B cel...

Introduction: Dark neurons which their morphological characteristics are consistent with those of cells undergoing apoptosis, are generated as an acute or delayed consequence of several pathological situations. The present study was designed to evaluate whether inflammatory pain regarding the role of NO and JNK lead to the formation of dark neurons in the dorsal horn of the lumbar spinal cor...

Four different types of lectin were applied to the rabbit conjunctiva and the lacrimal sac to examine the distribution of glycoconjugates. The conjunctival epithelium is comprised of goblet cells and nongoblet cells. The mucus granules of the goblet cells were stained with soybean agglutinin (SBA), and the cell body of the nongoblet cells was labeled with concanavalin A (Con A). The glycocalyx ...

A model of B cell affinity selection is proposed, and an explanation of peripheral tolerance mechanisms through antibody repertoire editing is presented. We show that affinity discrimination between B cells is driven by a competition between obtaining T cell help and removal of B cells from the light zone, either through apoptosis or by a return to the dark zone of germinal centers. We demonstr...

In this issue of JEM, Sulciner et al. (https://doi.org/10.1084/jem.20170681) provide evidence that therapy-induced cancer cell death can, paradoxically, stimulate and accelerate the growth of surviving malignant cells by fueling tumor-promoting inflammation. Resolvins, a class of lipid mediators, counteract this effect, representing an attractive target for therapeutic intervention.

I briefly review our current understanding of dark matter and dark energy. The first part of this paper focusses on issues pertaining to dark matter including observational evidence for its existence, current constraints and the ‘abundance of substructure’ and ‘cuspy core’ issues which arise in CDM. I also briefly describe MOND. The second part of this review focusses on dark energy. In this pa...

abstract in this experiment the effects of two type of medium cultures, gibberellic acid and dark/cold and light/warm culture conditions on mature embryos germination of a local cultivar of walnut were investigated. the mature fruits were collected at 22 weeks postanthesis and after disinfection the mature embryo along with cotyledon pieces were excised and then were cultured on mt and modified...

objectives : optimum viewing conditions facilitate identification of radiographic details and decrease the need for retakes, patients’ costs and radiation dose. this study sought to evaluate the effects of different viewing conditions on radiographic interpretation. materials and methods: this diagnostic study was performed by evaluating radiograph of a 7mm-thick aluminum block, in which 10 hol...