Growth factors upregulate deposition and remodeling of ECM by endothelial cells cultured for tissue-engineering applications

Appropriate matrix formation, turnover and remodeling in tissue-engineered small diameter vascular conduits are crucial for their long-term function. The interaction between cells and extra-cellular components is indispensable in determining cellular behavior in tissues and on biomaterials. The fibrin that contains fibronectin shows promise in most aspects as a tissue engineering scaffold, whereas, deposition of elastin and collagen by endothelial cells grown in the lumen of the construct is desirable to improve post implant retention, mechanical stability and vaso-responsiveness. So far there is no report on production of extra-cellular matrix (ECM) proteins, elastin and collagen by endothelial cells (EC) in in vitro culture conditions. In this study, we have used a biomimetic approach of providing multiple growth factors (GF) in the fibronectin (FN)-containing fibrin matrix to induce production of elastin and collagen by the endothelial cells for application in vascular tissue engineering. Deposition of elastin and collagens with matrix remodeling is demonstrated through qualitative analysis of the matrices that were recovered after growing cells on the initial fibrin-FN-GF matrix. Expressions of mRNA for both proteins were assessed by real time polymerase chain reaction (RT-PCR) to estimate the effects of multiple growth factor compositions. Marked deposition of elastin and collagen was evidenced by staining the recovered matrix after different culture intervals. Obviously, the biomimetic environment created by adding angiogenic and platelet growth factors in the fibrin-fibronectin-gelatin matrix can induce deposition of collagens and elastin by EC.     

Advances in rice breeding,genetics and genomics

Molecular Breeding -     

A Bovine Lymphosarcoma Cell Line Infected with Theileria annulata Exhibits an Irreversible Reconfiguration of Host Cell Gene Expression

Theileria annulata, an intracellular parasite of bovine lymphoid cells, induces substantial phenotypic alterations to its host cell including continuous proliferation, cytoskeletal changes and resistance to apoptosis. While parasite induced modulation of host cell signal transduction pathways and NFκB activation are established, there remains considerable speculation on the complexities of the parasite directed control mechanisms that govern these radical changes to the host cell. Our objectives in this study were to provide a comprehensive analysis of the global changes to host cell gene expression with emphasis on those that result from direct intervention by the parasite. By using comparative microarray analysis of an uninfected bovine cell line and its Theileria infected counterpart, in conjunction with use of the specific parasitacidal agent, buparvaquone, we have identified a large number of host cell gene expression changes that result from parasite infection. Our results indicate that the viable parasite can irreversibly modify the transformed phenotype of a bovine cell line. Fifty percent of genes with altered expression failed to show a reversible response to parasite death, a possible contributing factor to initiation of host cell apoptosis. The genes that did show an early predicted response to loss of parasite viability highlighted a sub-group of genes that are likely to be under direct control by parasite infection. Network and pathway analysis demonstrated that this sub-group is significantly enriched for genes involved in regulation of chromatin modification and gene expression. The results provide evidence that the Theileria parasite has the regulatory capacity to generate widespread change to host cell gene expression in a complex and largely irreversible manner.     

Reproductive biology of the golden catfish,Horabagrus brachysoma (Günther, 1864), an endemic species of the Western Ghats,India

To study the reproductive biology of Horabagrus brachysoma (Günther, 1864), monthly samples were collected from the riverine stretches of Lake Vembanad during 2001–2002. The sexes can be distinguished only during the breeding season; male to female ratio in the exploited catch was 1 : 1.97. The mean L_T at first maturity (L₅₀) was 18.5 cm in females and 17.5 cm in males. Absolute fecundity varied between 1100 and 124 000, with a mean of 20 472. The ovary showed group synchronous development and the oocyte diameter varied between 0.13 and 1.63 mm. The relatively high fecundity and hardy nature of H. brachysoma may favour the expansion of this indigenous catfish throughout the culture systems.