Cytochrome oxidase staining reveals functionally important activity bands in the olfactory epithelium of newborn rat

Segmentation of the Haematoxylin and Eosin Stained Muscle Cell Images—A Comparative Study

The effective detection of muscle cells, the accurate counting of their numbers and the analysis of their morphological features have great importance in biomedical research. At present, the quantification of muscle cell and the computation of their cross-sectional areas (CSA) are still manual or semi-automated, and with the increase of the image number, the manual or semi-automated methods might become intractable. Hence, the automatic methods are very desirable, which motivated the developments of many muscle cell segmentation methods. In this paper, three methods, SDDM, CELLSEGM and SMASH are compared and evaluated with 100 images with over 6000 cells. The Dices computed by SDDM, CELLSEGM and SMASH are 97.38%, 89.85% and 90.08% respectively. The average differences between the calculated cross-sectional areas and the ground truths by SDDM, CELLSEGM and SMASH are 5.14%, 10.76% and 7.97% respectively.

A unique transcriptome at the brain-environment interface: local translation in the rat olfactory epithelium

All olfactory epithelium cells, including rapidly self-renewing olfactory sensory neurons (OSN), are continuously subjected to external airborne aggressions. We hypothesized that the apical part of rat olfactory epithelia (AOE) could be the site of a local translation to be able to respond rapidly to external stimuli. We purified significant amounts of mRNAs from AOE. Sequencing of the cDNA library identified 348 mRNA species. Of these, the 220 AOE transcripts encoding proteins with known biological functions were classified in functional groups. The main functional class (40%) coded for defense, detoxification, anti-oxidant stress and innate immunity. Other classes comprised mRNAs encoding functions for neuronal metabolism and life (19%), nuclear transcription control (15%), cell survival and proliferation (13%), RNA processing and translation (12%). They did not contain any known members of the olfactory transduction pathway. The expression of a sub-set of AOE transcripts was investigated in sub-cellular AOE fractions highly enriched in ciliated dendrites and in AOE fractions after forced hemilateral OSN-specific degeneration. All the mRNAs tested were found to be: i) present in enriched ciliated dendrite preparations ii) down-regulated after OSN degeneration iii) co-purified with polysomal fractions, suggesting their commitment to local translation. We provide strong evidence that the extreme apical side of the olfactory epithelium expresses a unique transcriptome, whose function is not related to olfaction but mainly to defense and survival. The possible local translation of this transcriptome is demonstrated, in supporting cells as well as in olfactory neuron ciliated dendrites.

Calcium-signaling networks in olfactory receptor neurons

The olfactory neuroepithelium represents a unique interface between the brain and the external environment. Olfactory function comprises a distinct set of molecular tasks: sensory signal transduction, cytoprotection and adult neurogenesis. A multitude of biochemical studies has revealed the central role of Ca(2+) signaling in the function of olfactory receptor neurons (ORNs). We set out to establish Ca(2+)-dependent signaling networks in ORN cilia by proteomic analysis. We subjected a ciliary membrane preparation to Ca(2+)/calmodulin-affinity chromatography using mild detergent conditions in order to maintain functional protein complexes involved in olfactory Ca(2+) signaling. Thus, calmodulin serves as a valuable tool to gain access to novel Ca(2+)-regulated protein complexes. Tandem mass spectrometry (nanoscale liquid-chromatography-electrospray injection) identified 123 distinct proteins. Ninety-seven proteins (79%) could be assigned to specific olfactory functions, including 32 to sensory signal transduction and 40 to cytoprotection. We point out novel perspectives for research on the Ca(2+)-signaling networks in the olfactory system of the rat.

Marked recovery of functional metabolic activity and laminar volumes in the rat hippocampus and dentate gyrus following postnatal hypothyroid growth retardation: A quantitative cytochrome oxidase study

Similar to cretinism in human children, absence or deficiency of thyroid hormones in rats and mice during early postnatal development results in marked retardation of brain development along with behavioral and cognitive deficits. Less is known about brain recovery from postnatal hypothyroidism. [Farahvar, A., Meisami, E., 2007. Novel two-dimensional morphometric maps and quantitative analysis reveal marked growth and structural recovery of the rat hippocampal regions from early hypothyroid retardation. Experimental Neurology.] found, by means of morphometric maps, that surface areas of hippocampal cortex and its CA1-CA4 regions which were significantly reduced in developing hypothyroid rats, show nearly complete growth recovery upon restoration of thyroid function. Here we explore the ability of hippocampal synapse-rich neuronal fiber layers to show recovery from early hypothyroid growth retardation. Rat pups were made hypothyroid from birth to day 25 (weaning) or up to young adulthood (day 90) by a treatment with the reversible goitrogen, PTU (n-propylthiouracil), in the drinking water. Recovery was induced by withdrawal of PTU at weaning and analysis of cytochrome oxidase (CytOx)-stained serial sections of the hippocampus and dentate gyrus at the ages of 25 and 90 days. CytOx stains the synapse-rich fiber layers of the hippocampal formation (HCF). Volumetric growth of molecular layer, stratum oriens and radiatum and dentate hilar region showed complete or nearly complete recovery from marked and significant growth retardation induced by early postnatal hypothyroidism. Also the reduced CytOx staining intensity in the hypothyroid rat HCF layers showed marked recovery following hormonal restoration. Results indicate remarkable growth plasticity of the HCF and ability of the synapse-rich fiber layers to show complete recovery of metabolic and functional neural activity from deleterious effects of early hypothyroidism. Mitochondrial CytOx is highly localized to the synapse-rich fiber layers of the HCF and its activity and histochemical staining intensity correlates positively with functional metabolic activity of neural tissue. Thus hippocampus and dentate gyrus neuronal fiber layers and their oxidative activity show remarkable ability to recover from the postnatal hypothyroid growth retardation. The results indicate that some brain regions are less vulnerable to early developmental insults and can recover.