Reproductive biology of the endemic Iranian cichlid, <Emphasis Type="Italic">Iranocichla hormuzensis</Emphasis> Coad, 1982 from Mehran River,southern Iran

We studied the reproductive biology of the endemic Iranian cichlid Iranocichla hormuzensis, a maternal mouthbrooder, in the Mehran River. Overall sex ratio was 1.44 M: 1F indicating a significant male bias. Monthly sex ratios did not differ from unity except in May and June when the sex ratios were strongly biased in favor of males. Four different reproductive indices and the high frequency of large oocytes, all suggest that the Iranian cichlid spawns at the end of winter and the beginning of spring. Mircoscopic gonadal maturation stages for both males and females were correlated to the gonadosomatic indices. The maximum number of larvae in the mouth of a female was 153.     

Lectins influence chondrogenesis and osteogenesis in limb bud mesenchymal cells

The role of cell surface glycoproteins in cell behavior can be characterized by their interactions with plant lectins. This study was designed to identify the effects of lectins on chondrogenesis and osteogenesis in limb bud mesenchymal cells in vitro. Limb bud mesenchymal cells from mouse embryos were cultured in high-density micromass culture. Wheat germ agglutinin (WGA), concanavalin A (ConA), peanut agglutinin (PNA), Dolichos biflorus agglutinin (DBA) and Ricinus communis agglutinin (RCA) were added separately to the culture media. Cells were cultured for 5 or 9 days, and cell viability was assayed by neutral red on day 5. The micromasses were stained with alcian blue, alizarin red S and Von Kossa stains, and alkaline phosphatase assays were also done. Dolichos biflorus agglutinin induced an increase in chondrogenesis, calcium precipitation and proteoglycan production. ConA and PNA did not affect chondrocyte differentiation but induced chondrocytes to produce more proteoglycan. Wheat germ agglutinin reduced chondrification and ossification but induced mesenchymal cells to store lipid droplets. Ricinus communis agglutinin 1 was toxic and significantly reduced cell survival. In conclusion, DBA was the most effective inducer of ossification and chondrification. Wheat germ agglutinin induced adipogenesis instead. These assays showed that lectins play important roles in limb bud development.     

Computational Analysis of AMPK-Mediated Neuroprotection Suggests Acute Excitotoxic Bioenergetics and Glucose Dynamics Are Regulated by a Minimal Set of Critical Reactions

Loss of ionic homeostasis during excitotoxic stress depletes ATP levels and activates the AMP-activated protein kinase (AMPK), re-establishing energy production by increased expression of glucose transporters on the plasma membrane. Here, we develop a computational model to test whether this AMPK-mediated glucose import can rapidly restore ATP levels following a transient excitotoxic insult. We demonstrate that a highly compact model, comprising a minimal set of critical reactions, can closely resemble the rapid dynamics and cell-to-cell heterogeneity of ATP levels and AMPK activity, as confirmed by single-cell fluorescence microscopy in rat primary cerebellar neurons exposed to glutamate excitotoxicity. The model further correctly predicted an excitotoxicity-induced elevation of intracellular glucose, and well resembled the delayed recovery and cell-to-cell heterogeneity of experimentally measured glucose dynamics. The model also predicted necrotic bioenergetic collapse and altered calcium dynamics following more severe excitotoxic insults. In conclusion, our data suggest that a minimal set of critical reactions may determine the acute bioenergetic response to transient excitotoxicity and that an AMPK-mediated increase in intracellular glucose may be sufficient to rapidly recover ATP levels following an excitotoxic insult.     

Mantle histology and histochemistry of three pearl oysters: Pinctada persica,Pinctada radiata and Pteria penguin

Shells in pearl oysters are produced by the mantle which is also used as a graft in pearl operations. Here, we investigate the mantle structure of a new pearl oyster species of the Persian Gulf, Pinctada persica, and compare it to two other pearl-producing species, Pinctada radiata and Pteria penguin. The anterior, ventral and posterior segments of the mantle edge of each valve were fixed, and tissue sections were stained with haematoxylin and eosin. A new pentachrome method and PAS-alcian blue staining were used to characterise the different mucosubstances. The mantle edges were found to have an outer, middle and inner fold, which have different morphology in each species. The mantle edge is lined by cuboidal and columnar epithelia, and interspersed among these epithelial cells we found mucous cells and cells that contained brown granules. The outer and middle folds of the two Pinctada species show different shapes to that of Pteria penguin. Most of the mucous cells in the mantle contain acidic mucosubstances and small amounts of mixed acidic-neutral mucosubstances were observed in the middle and inner fold of Pinctada persica. This study reveals that the mantle edges of the three species possess similar cellular structure, but vary in the shape of the folds.     

Extracellular Signal-Regulated Kinase Regulates RhoA Activation and Tumor Cell Plasticity by Inhibiting Guanine Exchange Factor H1 Activity

In certain Ras mutant cell lines, the inhibition of extracellular signal-regulated kinase (ERK) signaling increases RhoA activity and inhibits cell motility, which was attributed to a decrease in Fra-1 levels. Here we report a Fra-1-independent augmentation of RhoA signaling during short-term inhibition of ERK signaling. Using mass spectrometry-based proteomics, we identified guanine exchange factor H1 (GEF-H1) as mediating this effect. ERK binds to the Rho exchange factor GEF-H1 and phosphorylates it on S959, causing inhibition of GEF-H1 activity and a consequent decrease in RhoA activity. Knockdown experiments and expression of a nonphosphorylatable S959A GEF-H1 mutant showed that this site is crucial in regulating cell motility and invasiveness. Thus, we identified GEF-H1 as a critical ERK effector that regulates motility, cell morphology, and invasiveness.     

Searching for Synergies: Matrix Algebraic Approaches for Efficient Pair Screening

Functionally interacting perturbations, such as synergistic drugs pairs or synthetic lethal gene pairs, are of key interest in both pharmacology and functional genomics. However, to find such pairs by traditional screening methods is both time consuming and costly. We present a novel computational-experimental framework for efficient identification of synergistic target pairs, applicable for screening of systems with sizes on the order of current drug, small RNA or SGA (Synthetic Genetic Array) libraries (>1000 targets). This framework exploits the fact that the response of a drug pair in a given system, or a pair of genes'' propensity to interact functionally, can be partly predicted by computational means from (i) a small set of experimentally determined target pairs, and (ii) pre-existing data (e.g. gene ontology, PPI) on the similarities between targets. Predictions are obtained by a novel matrix algebraic technique, based on cyclical projections onto convex sets. We demonstrate the efficiency of the proposed method using drug-drug interaction data from seven cancer cell lines and gene-gene interaction data from yeast SGA screens. Our protocol increases the rate of synergism discovery significantly over traditional screening, by up to 7-fold. Our method is easy to implement and could be applied to accelerate pair screening for both animal and microbial systems.