8-Oxoerythrinine: An alkaloid from Erythrina brucei

The flowers of Erythrina brucei afforded, in addition to known compounds, a new erythrina alkaloid, 8-oxoerythrinine. Its structure was elucidated by spectroscopic investigations as well as by chemical transformations.     

The Biological Significance of the Pair-bond in the Shrimp Hymenocera picta

The painted shrimp exhibits a social system of “relative monogamy”. The selective consequences of mate attachment for the individuals have been studied by long term observations and experiments.     

Cytoplasmic thioredoxin reductase is essential for embryogenesis but dispensable for cardiac development

Two distinct thioredoxin/thioredoxin reductase systems are present in the cytosol and the mitochondria of mammalian cells. Thioredoxins (Txn), the main substrates of thioredoxin reductases (Txnrd), are involved in numerous physiological processes, including cell-cell communication, redox metabolism, proliferation, and apoptosis. To investigate the individual contribution of mitochondrial (Txnrd2) and cytoplasmic (Txnrd1) thioredoxin reductases in vivo, we generated a mouse strain with a conditionally targeted deletion of Txnrd1. We show here that the ubiquitous Cre-mediated inactivation of Txnrd1 leads to early embryonic lethality. Homozygous mutant embryos display severe growth retardation and fail to turn. In accordance with the observed growth impairment in vivo, Txnrd1-deficient embryonic fibroblasts do not proliferate in vitro. In contrast, ex vivo-cultured embryonic Txnrd1-deficient cardiomyocytes are not affected, and mice with a heart-specific inactivation of Txnrd1 develop normally and appear healthy. Our results indicate that Txnrd1 plays an essential role during embryogenesis in most developing tissues except the heart.     

Molecular phylogeny of Megaloceros giganteus--the giant deer or just a giant red deer?

Two fragments of mitochondrial DNA (mtDNA) of the cytochrome b gene (137 bp and 167 bp) were successfully isolated and sequenced from antlers and bones of five specimens of the Giant Deer (Megaloceros giganteus) to examine the phylogenetic position of Megaloceros giganteus within the family Cervidae. This is the first report on ancient DNA (aDNA) sequences from Megaloceros giganteus. A phylogenetic analysis based on parameter-rich models describes the evolutionary relationships between five individuals of fossil Megaloceros giganteus and 37 individuals of 11 extant species of the family Cervidae. The results support a "Cervus-Megaloceros" clade. The phylogenetic positions of sympatric Megaloceros and Cervus elaphus specimens in particular indicate either that the Megaloceros mtDNA gene pool did not evolve for a substantial time period as an entity distinct from Cervus elaphus until its extinction, or that Megaloceros contributed mtDNA to Cervus elaphus or vice versa. The results of this study allow the conclusion that the European Megaloceros giganteus is more related to its modern regional counterparts of the species of Cervus elaphus than recent claims have suggested.     

Remodeling of the vascular tunica media is essential for development of collateral vessels in the canine heart

Previous studies have shown that neointima formation and adventitial remodeling play an important role in the enlargement of collateral vessels (CVs) during coronary arteriogenesis in the dog heart. In this study, we investigated the importance of remodeling of the tunica media in the same model. Basal membrane (BM), contractile and cytoskeletal components of smooth muscle cells (SMCs) were studied in growth of coronary CVs induced by chronic occlusion of the left circumflex (LCX) coronary artery by routine histology, electron microscopy (EM), and immunoconfocal microscopy using antibodies against α-smooth actin (α-SM actin), calponin, desmin, and laminin. In addition, matrix metalloproteinase-2 (MMP-2) and tissue inhibitor-1 of matrix metalloproteinase (TIMP-1) were investigated. The data showed that (1) in normal small arteries (NVs) laminin formed a network in which SMCs were encaged;α-SM actin, calponin and desmin were evenly expressed in SMCs; (2) in early (2 weeks) growing CVs the laminin network was disrupted, desmin was significantly reduced in SMCs, but α-SM actin and calponin still highly expressed; (3) in actively (6 weeks) growing CVs laminin was still weak in the tunica media (TM), but without network-like structure. Desmin was further reduced in SMCs of TM, whereas α-SM actin and calponin showed little changes, although they were significantly decreased in intimal SMCs; (4) in mature CVs, the network-like structure was re-formed, and α-SM actin, calponin, and desmin were all similar to that in normal vessels; (5) histology for BM confirmed laminin staining; (6) EM revealed that in NVs the SMCs contained abundant contractile filaments and were surrounded by a layer of BM whereas in growing CVs, BM structure was not observed, but the SMCs in the media still contained many myofilaments; (7) MMP-2 was highly expressed in the media of early growing vessels, but decreased in TM of actively growing vessels where TIMP-1 expression was high. In conclusion, our data revealed features of TM of growing CVs. Disruption and degradation of BM facilitate SMC proliferation, and together with reduction of desmin and fragmentation of the internal elastic lamina enable the vascular wall to expand and enlarge when blood pressure and shear stress increase. MMP2 may be an important player in regulating SMC phenotype, proliferation, migration and maintaining integrity of the vascular wall through governing proteolysis during arteriogenesis. (Mol Cell Biochem 264: 201–210, 2004)