Controlling structural and functional features of photosynthetic antenna

In order to gain control over the assembly and functioning of photosynthetic antenna, we have developed methods to manipulate pigment composition of bacterial LH1 complexes via their reconstitution with modified bacteriochlorophylls or carotenoids, major photoactive cofactors of these antennae. In the present work we show how the reconstitution and pigment exchange approach is applied to control structural and functional parameters of LH1 and its subunits. The size of the subunits and the energy of the first excited singlet state can be controlled via the use of detergent while the thermodynamics of LH1 formation can be modified using carotenoids and/or a co-solvent. Carotenoids affect the efficiency of the intracomplex energy transfer, while the replacement of native bacteriochlorophyll a with its Ni-substituted analog allows one to control the excited state properties of LH1. These results show that LH1 is a very promising model system applicable for the design of bio-inspired device performing solar energy conversion

Flutamide induces alterations in the cell-cell junction ultrastructure and reduces the expression of Cx43 at the blood-testis barrier with no disturbance in the rat seminiferous tubule morphology

BACKGROUND: Present study was designed to establish a causal connection between changes in the cell-cell junction protein expression at the blood-testis barrier and alterations in the adult rat testis histology following an anti-androgen flutamide exposure. Particular emphasis was placed on the basal ectoplasmic specialization (ES) in the seminiferous epithelium and expression of gap junction protein, connexin 43 (Cx43). METHODS: Flutamide (50 mg/kg body weight) was administered to male rats daily from 82 to 88 postnatal day. Testes from 90-day-old control and flutamide-exposed rats were used for all analyses. Testis morphology was analyzed using light and electron microscopy. Gene and protein expressions were analyzed by real-time RT-PCR and Western blotting, respectively, protein distribution by immunohistochemistry, and steroid hormone concentrations by radioimmunoassay. RESULTS: Seminiferous epithelium of both groups of rats displayed normal histology without any loss of germ cells. In accord, no difference in the apoptosis and proliferation level was found between control and treated groups. As shown by examination of semi-thin and ultrathin sections, cell surface occupied by the basal ES connecting neighboring Sertoli cells and the number of gap and tight junctions coexisting with the basal ES were apparently reduced in flutamide-treated rats. Moreover, the appearance of unconventional circular ES suggests enhanced internalization and degradation of the basal ES. These changes were accompanied by decreased Cx43 and ZO-1 expression (p < 0.01) and a loss of linear distribution of these proteins at the region of the blood-testis barrier. On the other hand, Cx43 expression in the interstitial tissue of flutamide-treated rats increased (p < 0.01), which could be associated with Leydig cell hypertrophy. Concomitantly, both intratesticular testosterone and estradiol concentrations were elevated (p < 0.01), but testosterone to estradiol ratio decreased significantly (p < 0.05) in flutamide-treated rats compared to the controls. CONCLUSIONS: Short-term treatment with flutamide applied to adult rats exerts its primary effect on the basal ES, coexisting junctional complexes and their constituent proteins Cx43 and ZO-1, without any apparent morphological alterations in the seminiferous epithelium. In the interstitial compartment, however, short-term exposure leads to both histological and functional changes of the Leydig cells

The role of G-protein-coupled membrane estrogen receptor in mouse Leydig cell function : in vivo and in vitro evaluation

AbstractIn this study, G-coupled estrogen receptor (GPER) was inactivated, by treatment with antagonist (G-15), in testes of C57BL/6 mice: immature (3 weeks old), mature (3 months old) and aged (1.5 years old) (50 μg/kg bw), as well as MA-10 mouse Leydig cells (10 nM/24 h) alone or in combination with 17β-estradiol or antiestrogen (ICI 182,780). In G-15-treated mice, overgrowth of interstitial tissue was found in both mature and aged testes. Depending on age, differences in structure and distribution of various Leydig cell organelles were observed. Concomitantly, modulation of activity of the mitochondria and tubulin microfibers was revealed. Diverse and complex GPER regulation at the mRNA level and protein of estrogen signaling molecules (estrogen receptor α and β; ERα, ERβ and cytochrome P450 aromatase; P450arom) in G-15 Leydig cells was found in relation to age and the experimental system utilized (in vivo and in vitro). Changes in expression patterns of ERs and P450arom, as well as steroid secretion, reflected Leydig cell heterogeneity to estrogen regulation throughout male life including cell physiological status.We show, for the first time, GPER with ERs and P450arom work in tandem to maintain Leydig cell architecture and supervise its steroidogenic function by estrogen during male life. Full set of estrogen signaling molecules, with involvement of GPER, is crucial for proper Leydig cell function where each molecule acts in a specific and/or complementary manner. Further understanding of the mechanisms by which GPER controls Leydig cells with special regard to male age, cell of origin and experimental system used is critical for predicting and preventing testis steroidogenic disorders based on perturbations in estrogen signaling.</jats:p

Temporal relationship between systemic endothelial dysfunction and alterations in erythrocyte function in a murine model of chronic heart failure

Endothelial dysfunction (ED) and red blood cell distribution width (RDW) are both prognostic factors in heart failure (HF), but the relationship between them is not clear. In this study, we used a unique mouse model of chronic HF driven by cardiomyocyte-specific overexpression of activated Gαq protein (Tgαq*44 mice) to characterise the relationship between the development of peripheral ED and the occurrence of structural nanomechanical and biochemical changes in red blood cells (RBCs).Systemic ED was detected in vivo in 8-month-old Tgαq*44 mice, as evidenced by impaired acetylcholine-induced vasodilation in the aorta and increased endothelial permeability in the brachiocephalic artery. ED in the aorta was associated with impaired nitric oxide (NO) production in the aorta and diminished systemic NO bioavailability. ED in the aorta was also characterised by increased superoxide and eicosanoid production. In 4- to 6-month-old Tgαq*44 mice, RBC size and membrane composition displayed alterations that did not result in significant changes in their nanomechanical and functional properties. However, 8-month-old Tgαq*44 mice presented greatly accentuated structural and size changes and increased RBC stiffness. In 12-month-old Tgαq*44 mice, the erythropathy was featured by severely altered RBC shape and elasticity, increased RDW, impaired RBC deformability, and increased oxidative stress (GSH/GSSH ratio). Moreover, RBCs taken from 12-month-old Tgαq*44 mice, but not from 12-month-old FVB mice, co-incubated with aortic rings from FVB mice, induced impaired endothelium-dependent vasodilation and this effect was partially reversed by an arginase inhibitor (ABH, 2(S)-amino-6-boronohexanoic acid).In the Tgαq*44 murine model of HF, systemic endothelial dysfunction accelerates erythropathy and, conversely, erythropathy may contribute to endothelial dysfunction. These results suggest that erythropathy may be regarded as a marker and a mediator of systemic endothelial dysfunction in HF. In particular, targeting RBC arginase may represent a novel treatment strategy for systemic endothelial dysfunction in HF. RBC arginase and possibly other RBC-mediated mechanisms may represent novel therapeutic targets for systemic endothelial dysfunction in HF.Endothelial dysfunction (ED) and red blood cell distribution width (RDW) both have prognostic value for heart failure (HF), but it is not known whether these pathologies are related. We comprehensively characterized endothelial and RBC functional status in a unique murine model of chronic heart failure with a prolonged time course of HF progression. Our results suggest that ED accelerates erythropathy and, conversely, erythropathy may contribute to ED. Accordingly, erythropathy in HF reflects ED and involves various changes (in functional, structural, nanomechanical, and biochemical levels) that could have diagnostic and therapeutic significance for HF