Photosynthetic eukaryotes unite: endosymbiosis connects the dots

The photosynthetic organelle of algae and plants (the plastid) traces its origin to a primary endosymbiotic event in which a previously non-photosynthetic protist engulfed and enslaved a cyanobacterium. This eukaryote then gave rise to the red, green and glaucophyte algae. However, many algal lineages, such as the chlorophyll c-containing chromists, have a more complicated evolutionary history involving a secondary endosymbiotic event, in which a protist engulfed an existing eukaryotic alga (in this case, a red alga). Chromists such as diatoms and kelps then rose to great importance in aquatic habitats. Another algal group, the dinoflagellates, has undergone tertiary (engulfment of a secondary plastid) and even quaternary endosymbioses. In this review, we examine algal diversity and show endosymbiosis to be a major force in algal evolution. This area of research has advanced rapidly and long-standing issues such as the chromalveolate hypothesis and the extent of endosymbiotic gene transfer have recently been clarified.     

Complexity in the vascular permeability factor/vascular endothelial growth factor (VPF/VEGF)-receptors signaling

The adult vasculature results from a network of vessels that is originally derived in the embryo by vasculogenesis, a process whereby vessels are formed de novo from endothelial cell (EC) precursors, known as angioblasts. During vasculogenesis, angioblasts proliferate and come together to form an initial network of vessels, also known as the primary capillary plexus. Sprouting and branching of new vessels from the preexisting vessels in the process of angiogenesis remodel the capillary plexus. Normal angiogenesis, a well-balanced process, is important in the embryo to promote primary vascular tree as well as an adequate vasculature from developing organs. On the other hand, pathological angiogenesis which frequently occurs in tumors, rheumatoid arthritis, diabetic retinopathy and other circumstances can induce their own blood supply from the preexisting vasculature in a route that is close to normal angiogenesis. Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) is perhaps the most important of pro-angiogenic cytokine because of its ability to regulate most of the steps in the angiogenic cascade. The main goal of this review article is to discuss the complex nature of the mode of action of VPF/VEGF on vascular endothelium. To this end, we conclude that more research needs to be done for completely understanding the VPF/VEGF biology with relation to angiogenesis.     

Photoelectric response of polarization sensitive bacteriorhodopsin films

Polarization sensitivity is introduced into oriented bacteriorhodopsin (BR) films through a photochemical bleaching process, which chemically modifies the structure of the purple membrane by breaking the intrinsic symmetry of the membrane-bound BR trimers. The resulting photovoltage generated in an indium-tin oxide (ITO)/BR/ITO detector is found to be anisotropic with respect to cross-polarized probe beams. A model, based on the polarization dependent photoselection of the BR molecules qualitatively explains the photochemical bleaching process and the observed anisotropic response. The effect reported here can be used to construct a polarization sensitive BR-based bio-photoreceiver.     

Purification and characterization of 9-O-acetylated sialoglycoproteins from leukemic cells and their potential as immunological tool for monitoring childhood acute lymphoblastic leukemia

Sialic acids as terminal residues of oligosaccharide chains play crucial roles in several cellular recognition events. Exploiting the selective affinity of Achatinin-H toward N-acetyl-9-O-acetylneuraminic acid-alpha2-6-GalNAc, we have demonstrated the presence of 9-O-acetylated sialoglycoproteins (Neu5,9Ac(2)-GPs) on lymphoblasts of 70 children with acute lymphoblastic leukemia (ALL) and on leukemic cell lines by fluorimetric HPLC and flow cytometric analysis. This study aims to assess the structural aspect of the glycotope of Neu5,9Ac(2)-GPs(ALL) and to evaluate whether these disease-specific molecules can be used to monitor the clinical outcome of ALL. The Neu5,9Ac(2)-GPs(ALL) were affinity-purified, and three distinct leukemia-specific molecular determinants (135, 120, and 90 kDa) were demonstrated by SDS-PAGE, western blotting, and isoelectric focusing. The carbohydrate epitope of Neu5,9Ac(2)-GPs(ALL) was confirmed by using synthetic sialic acid analogs. The enhanced presence of anti-Neu5,9Ac(2)-GP(ALL) antibody in ALL patients prompted us to develop an antigen-ELISA using purified Neu5,9Ac(2)-GPs(ALL) as coating antigens. Purified antigen was able to detect leukemia-specific antibodies at presentation of disease, which gradually decreased with treatment. Longitudinal monitoring of 18 patients revealed that in the early phase of the treatment patients with lower anti-Neu5,9Ac(2)-GPs showed a better prognosis. Minimal cross-reactivity was observed in other hematological disorders (n = 50) like chronic myeloid leukemia, acute myelogenous leukemia, chronic lymphocytic leukemia, and non-Hodgkin's lymphoma as well as normal healthy individuals (n = 21). This study demonstrated the potential of purified Neu5,9Ac(2)-GPs(ALL) as an alternate tool for detection of anti-Neu5,9Ac(2)-GP antibodies to be helpful for diagnosis and monitoring of childhood ALL patients.     

Functional equivalence of dihydropyridine receptor alpha1S and beta1a subunits in triggering excitation-contraction coupling in skeletal muscle

Molecular understanding of the mechanism of excitation-contraction (EC) coupling in skeletal muscle has been made possible by cultured myotube models lacking specific dihydropyridine receptor (DHPR) subunits and ryanodine receptor type 1 (RyR1) isoforms. Transient expression of missing cDNAs in mutant myotubes leads to a rapid recovery, within days, of various Ca2+ current and EC coupling phenotypes. These myotube models have thus permitted structure-function analysis of EC coupling domains present in the DHPR controlling the opening of RyR1. The purpose of this brief review is to highlight advances made by this laboratory towards understanding the contribution of domains present in alpha1S and beta1a subunits of the skeletal DHPR to EC coupling signaling. Our main contention is that domains of the alpha1S II-III loop are necessary but not sufficient to recapitulate skeletal-type EC coupling. Rather, the structural unit that controls the EC coupling signal appears to be the alpha1S/beta1a pair.     

Mouse development and cell proliferation in the absence of D-cyclins

D-type cyclins (cyclins D1, D2, and D3) are regarded as essential links between cell environment and the core cell cycle machinery. We tested the requirement for D-cyclins in mouse development and in proliferation by generating mice lacking all D-cyclins. We found that these cyclin D1(-/-)D2(-/-)D3(-/-) mice develop until mid/late gestation and die due to heart abnormalities combined with a severe anemia. Our analyses revealed that the D-cyclins are critically required for the expansion of hematopoietic stem cells. In contrast, cyclin D-deficient fibroblasts proliferate nearly normally but show increased requirement for mitogenic stimulation in cell cycle re-entry. We found that the proliferation of cyclin D1(-/-)D2(-/-)D3(-/-) cells is resistant to the inhibition by p16(INK4a), but it critically depends on CDK2. Lastly, we found that cells lacking D-cyclins display reduced susceptibility to the oncogenic transformation. Our results reveal the presence of alternative mechanisms that allow cell cycle progression in a cyclin D-independent fashion.     

Changes in endogenous indole-3-acetic acid and some biochemical parameters during seed development in <Emphasis Type="Italic">Camellia sinensis</Emphasis> (L.) O. Kuntze

The role of endogenous indole-3-acetic acid (IAA), soluble proteins and RNA in the development of tea (Camellia sinensis (L). O. Kuntze) seeds was investigated in the present study. The state of continuum even at full maturity and lack of a clear end point to seed development as indicated by the persistence of appreciable contents of proteins at full maturity in all the seed parts further confirmed the ‘recalcitrant nature’ of the tea seeds. Unlike the orthodox seeds, the level of free IAA in tea embryos also remained high even at full maturity. The total RNA content remained high in the stages with high moisture content but declined with progressive decline in moisture content.     

Antineoplastic and antibacterial activity of some mononuclear Ru(II) complexes

These ligands (L) show a bidentate behavior, forming octahedral ruthenium complexes. The title complexes were subjected to in-vivo anticancer activity tests against a transplantable murine tumor cell line, Ehrlich's Ascitic Carcinoma (EAC) and in-vitro antibacterial activity against several Gram positive and Gram negative bacterial strains. [Ru(bpy)2(ihqs)]Cl2 and [Ru(bpy)2 (hc)]Cl2 (where bpy = 2,2'-bipyridine, ihqs = 7-iodo-8hydroxy quinoline-5-sulphonic acid and hc = 3-hydroxy coumarin) showed promising antitumor activity. Treatment with these complexes prolonged the life span of EAC bearing mice as well as decreased their tumor volume and viable ascitic cell count. All the tested complexes exhibited mild to moderate antibacterial activity.     

Hidden biodiversity of the extremophilic Cyanidiales red algae

The Cyanidiales is a group of asexual, unicellular red algae, which thrive in acidic and high temperature conditions around hot springs. These unicellular taxa have a relatively simple morphology and are currently classified into three genera, Cyanidium, Cyanidioschyzon and Galdieria. Little is known, however, about the biodiversity of Cyanidiales, their population structure and their phylogenetic relationships. Here we used a taxonomically broadly sampled three-gene data set of plastid sequences to infer a robust phylogenetic framework for the Cyanidiales. The phylogenetic analyses support the existence of at least four distinct Cyanidiales lineages: the Galdieria spp. lineage (excluding Galdieria maxima), the Cyanidium caldarium lineage, a novel monophyletic lineage of mesophilic Cyanidium spp. and the Cyanidioschyzon merolae plus Galdieria maxima lineage. Our analyses do not support the notion of a mesophilic ancestry of the Cyanidiales and suggest that these algae were ancestrally thermo-acidotolerant. We also used environmental polymerase chain reaction (PCR) for the rbcL gene to sample Cyanidiales biodiversity at five ecologically distinct sites at Pisciarelli in the Phlegrean Fields in Italy. This analysis showed a high level of sequence divergence among Cyanidiales species and the partitioning of taxa based on environmental conditions. Our research revealed an unexpected level of genetic diversity among Cyanidiales that revises current thinking about the phylogeny and biodiversity of this group. We predict that future environmental PCR studies will significantly augment known biodiversity that we have discovered and demonstrate the Cyanidiales to be a species-rich branch of red algal evolution.