Connective Tissue Growth Factor Overexpression in Cardiomyocytes Promotes Cardiac Hypertrophy and Protection against Pressure Overload

Connective tissue growth factor (CTGF) is a secreted protein that is strongly induced in human and experimental heart failure. CTGF is said to be profibrotic; however, the precise function of CTGF is unclear. We generated transgenic mice and rats with cardiomyocyte-specific CTGF overexpression (CTGF-TG). To investigate CTGF as a fibrosis inducer, we performed morphological and gene expression analyses of CTGF-TG mice and rat hearts under basal conditions and after stimulation with angiotensin II (Ang II) or isoproterenol, respectively. Surprisingly, cardiac tissues of both models did not show increased fibrosis or enhanced gene expression of fibrotic markers. In contrast to controls, Ang II treated CTGF-TG mice displayed preserved cardiac function. However, CTGF-TG mice developed age-dependent cardiac dysfunction at the age of 7 months. CTGF related heart failure was associated with Akt and JNK activation, but not with the induction of natriuretic peptides. Furthermore, cardiomyocytes from CTGF-TG mice showed unaffected cellular contractility and an increased Ca2+ reuptake from sarcoplasmatic reticulum. In an ischemia/reperfusion model CTGF-TG hearts did not differ from controls

Observed variability of chlorophyll-a using Argo profiling floats in the southeastern Arabian Sea

The time series of temperature, salinity, chlorophyll-a, particle scattering at 700nm, and dissolved oxygen obtained from Argo floats deployed in the southeastern Arabian Sea (AS), were used to investigate the variability of these quantities and the mechanisms that modulate them between March 2010 and March 2011. The observations show a persistent occurrence of a subsurface chlorophyll-a maximum (0.75-1mgm -3) near depths of 40-100m throughout the study period, just above the top of permanent thermocline and euphotic depth. The analysis shows that upward and downward movement of thermocline, which is primarily due to westward movement of low-mode baroclinic Rossby waves, significantly influences the depth of the subsurface chlorophyll maxima and its intensity. Further, the vertical movement of the thermocline significantly influences the depth of the oxycline in the AS. The mixed layer deepening associated with wind induced vertical mixing and convective overturning lead to near surface blooms during the summer and winter monsoons. The analysis clearly shows that, in addition to entrainment of nutrients from rich subsurface water in the near surface layer, vertical fluxes from the subsurface chlorophyll maximum also contribute significantly to mixed layer blooms. The availability of light also plays an active role in the mixed layer bloom, particularly during the summer monsoon season