Light-induced degradation of storage starch in turions of Spirodela polyrhiza depends on nitrate

Light induces both the germination of turions of the duckweed Spirodela polyrhiza and the degradation of the reserve starch stored in the turions. The germination photoresponse requires nitrate, and we show here that nitrate is also needed for the light-induced degradation of the turion starch. Ammonium cannot substitute for nitrate in this regard, and nitrate thus acts specifically as signal to promote starch degradation in the turions. Irradiation with continuous red light leads to starch degradation via auto-phosphorylation of starch-associated glucan, water dikinase (GWD), phosphorylation of the turion starch and enhanced binding of alpha-amylase to starch granules. The present study shows that all of these processes require the presence of nitrate, and that nitrate exerts its effect on starch degradation at a point between the absorption of light by phytochrome and the auto-phosphorylation of the GWD. Nitrate acts to coordinate carbon and nitrogen metabolism in germinating turions: starch will only be broken down when sufficient nitrogen is present to ensure appropriate utilization of the released carbohydrate. These data constitute the first report of control over the initiation of reserve starch degradation by nitrate.     

Identification of structure and antioxidant activity of a fraction of polysaccharide purified from Dioscorea nipponica Makino

A large number of polysaccharides are present in boiling-water extraction of Dioscorea nipponica Makino. A DEAE-Sepharose CL-6B column chromatography was used to isolate the major polysaccharides from D. nipponica Makino. The largest amount of fraction of polysaccharide was subjected to further purification by gel-filtration on Sephadex G-100. The purified fraction was a neutral polysaccharide and a single peak in HPLC with Sugar KS-804 column, with a molecular weight of 38,000, and comprised mainly of glucose and fructose (45:1). Analysis by Periodate oxidation–Smith degradation indicated that there were 5.9%(1→)-glycosidic linkages, 4.94% (1 → 2)-glycosidic linkages, 61.16% (1 → 4)-glycosidic linkages, and 28% (1 → 3)-glycosidic linkages. On the basis of superoxide radical assay, hydroxyl radical assay, and self-oxidation of 1,2,3-phentriol assay, its antioxidant activity was investigated. This purified fraction of polysaccharide exhibited equivalent inhibiting power for self-oxidation of 1,2,3-phentriol to Vc, a little higher scavenging activity of superoxide radical and hydroxyl radical than Vc, and should be explored as a novel potential antioxidant.     

Acoustical Aspects of the Propagation of Long Calls of Wild <Emphasis Type="Italic">Leontopithecus rosalia</Emphasis>

Golden lion tamarins emit conspicuous and complex long calls. Little is known about the propagation distance of the calls, and the knowledge is important to understand the function of long calls. The high-frequency spectrum of the calls renders them susceptible to substantial degradation inside forest habitats. We investigated 1) the propagation distance of the long call and if the height from the ground affects the degree of degradation and 2) whether long-call acoustic variation affects the propagation distance. We conducted a playback study of 7 2-phrase long calls recorded at different distances (20, 40, 80, 120 m) and heights above ground (2 m and 7.5 m) in 3 transects of Brazilian Atlantic Forest. We quantified the degradation by measuring differences in the number of syllables and frequency measures of the calls at each distance. Degradation became significant at 80 m; the calls degraded below background noise at 120 m. The degradation of syllables was lower for recordings at 7.5 m above ground. The frequency spectra of the calls influenced significantly the propagation distance of the call. Because of the short propagation distance of long calls relative to territory size, we hypothesize that long calls may be adapted to avoiding ambient noise and that they evolved first for intragroup communication and then for territorial defense.     

Degradation of N-acyl homoserine lactone quorum sensing signal molecules by forest root-associated fungi

A collection of mycorrhizal and nonmycorrhizal root-associated fungi coming from forest environments was screened for their ability to degrade N-acyl homoserine lactones (AHL) or to prevent AHL recognition by producing quorum sensing inhibitors (QSI). No production of QS-inhibitors or -activators was detected using the two biosensors Chromobacterium violaceum CV026 and Agrobacterium tumefaciens in the culture supernatant of these fungi. However, the ability to degrade C6- and 3O,C6-HSL was detected for three fungal isolates. Acidification assay revealed that the AHL were degraded by a lactonase activity for two of these isolates. These results demonstrated for the first time that the forest root-associated fungi are capable of degrading the AHL signal molecules.     

An albumin–butyrylcholinesterase for cocaine toxicity and addiction: Catalytic and pharmacokinetic properties

Butyrylcholinesterase (BChE, EC 3.1.1.8) is important in human cocaine metabolism despite its limited ability to hydrolyze this drug. Efforts to improve the catalytic efficiency of this enzyme have led to a quadruple mutant cocaine hydrolase, “CocH”, that in animal models of addiction appears promising for treatment of overdose and relapse. We incorporated the CocH mutations into a BChE–albumin fusion protein, “Albu-CocH”, and evaluated the pharmacokinetics of the enzyme after i.v. injection in rats. As assessed from the time course of cocaine hydrolyzing activity in plasma, Albu-CocH redistributed into extracellular fluid (16% of estimated total body water) with a t_1/2 of 0.66 h and it underwent elimination with a t_1/2 of 8 h. These results indicate that the enzyme has ample stability for short-term applications and may be suitable for longer-term treatment as well. Present data also confirm the markedly enhanced power of Albu-CocH for cocaine hydrolysis and they support the view that Albu-CocH might prove valuable in treating phenomena associated with cocaine abuse.     

A nutritional model of late embryonic vitamin A deficiency produces defects in organogenesis at a high penetrance and reveals new roles for the vitamin in skeletal development

Vitamin A plays an essential role in vertebrate embryogenesis. In the present study, pregnant vitamin A-deficient (VAD) rats were maintained during early pregnancy on the short half-life vitamin A metabolite, all-trans retinoic acid (atRA), in an amount sufficient to support normal development to E10.5, with a higher level of atRA (250 μg atRA/g diet) provided from embryonic day (E) 8.5-10.5 to prevent mid-gestational resorption. When limiting amounts of atRA (1.5 or 12 μg/g diet) were provided after E10.5, a highly reproducible and penetrant state of late fetal vitamin A deficiency (late VAD) was induced in the organs of developing fetuses. In addition, late VAD fetuses displayed both anteriorization of cervical regions and novel posteriorization events at the thoracic and sacral levels of the skeleton, and showed sternal and pelvic malformations not previously observed in early VAD or genetic models. The expression of several Hox genes (Hoxd3 and Hoxb4) was altered in late VAD embryos, with a reduction in Hoxd3 noted as early as 1 day after instituting deficiency. All late VAD-induced malformations were prevented by the addition of retinol starting at E10.5, whereas provision of a high level of atRA throughout pregnancy improved but could not completely rescue the development of all organ systems. This work defines a nutritional model in which vitamin A deficiency can be induced during fetal development, and reveals new functions for the vitamin in the development of the axial and appendicular skeleton.     

Complex cell rearrangements during intersegmental vessel sprouting and vessel fusion in the zebrafish embryo

The formation of intersegmental blood vessels (ISVs) in the zebrafish embryo serves as a paradigm to study angiogenesis in vivo. ISV formation is thought to occur in discrete steps. First, endothelial cells of the dorsal aorta migrate out and align along the dorsoventral axis. The dorsal-most cell, also called tip cell, then joins with its anterior and posterior neighbours, thus establishing a simple vascular network. The vascular lumen is then established via formation of vacuoles, which eventually fuse with those of adjacent endothelial cells to generate a seamless tube with an intracellular lumen. To investigate the cellular architecture and the development of ISVs in detail, we have analysed the arrangement of endothelial cell junctions and have performed single cell live imaging. In contrast to previous reports, we find that endothelial cells are not arranged in a linear head-to-tail configuration but overlap extensively and form a multicellular tube, which contains an extracellular lumen. Our studies demonstrate that a number of cellular behaviours, such as cell divisions, cell rearrangements and dynamic alterations in cell-cell contacts, have to be considered when studying the morphological and molecular processes involved in ISV and endothelial lumen formation in vivo.     

PAR-6 levels are regulated by NOS-3 in a CUL-2 dependent manner in Caenorhabditiselegans

The PAR proteins have an essential and conserved function in establishing polarity in many cell types and organisms. However, their key upstream regulators remain to be identified. In C. elegans, regulators of the PAR proteins can be identified by their ability to suppress the lethality of par-2 mutant embryos. Here we show that a nos-3 loss of function mutant suppresses the lethality of par-2 mutants by regulating PAR-6 protein levels. The suppression requires the activity of the sex determination genes fem-1/2/3 and of the cullin cul-2. FEM-1 is a substrate-specific adaptor for a CUL-2-based ubiquitin ligase (CBC^FEM-1). Interestingly, we find that CUL-2 is required for the regulation of PAR-6 levels and that PAR-6 physically interacts with FEM-1. Our data strongly suggest that PAR-6 levels are regulated by the CBC^FEM-1 ubiquitin ligase thereby uncovering a novel role for the FEM proteins and cullin-dependent degradation in regulating PAR proteins and polarity processes.     

Multiple sex chromosome system of X1X1X2X2/X1X2)Y type in lutjanid fish, Lutjanus quinquelineatus (Perciformes)

The karyotype and other chromosomal markers as revealed by C-banding and Ag-staining were studied in Lutjanus quinquelineatus and L. kasmira (Lutjanidae, Perciformes). While in latter species, the karyotype was invariably composed of 48 acrocentric chromosomes in both sexes, in L. quinquelineatus the female karyotype had exclusively 48 acrocentric chromosomes (2n = 48) but that of the male consisted of one large metacentric and 46 acrocentric chromosomes (2n = 47). The chromosomes in the first meiotic division in males showed 22 bivalents and one trivalent, which was formed by an end-to-end association and a chiasmatic association. Multiple sex chromosome system of X₁X₁X₂X₂/X₁X₂Y type resulting from single Robertsonian fusion between the original Y chromosome and an autosome was hypothesized to produce neo-Y sex chromosome. The multiple sex chromosome system of L. quinquelineatus appears to be at the early stage of the differentiation. The positive C-banded heterochromatin was situated exclusively in centromeric regions of all chromosomes in both species. Similarly, nucleolus organizer region sites were identified in the pericentromeric region of one middle-sized pair of chromosomes in both species. The cellular DNA contents were the same (3.3 pg) between the sexes and among this species and related species.     

Ubiquitylation of ε-COP by PIRH2 and regulation of the secretion of PSA

Ubiquitylation appears to be involved in the membrane trafficking system including endocytosis, exocytosis, and ER-to-Golgi transport. We found that PIRH2, which was identified as an interacting protein for androgen receptor or p53, interacts with and ubiquitylates the ε-subunit of coatmer complex, ε-COP. PIRH2 promotes the ubiquitylation of ε-COP in vitro and in vivo and consequently promotes the degradation of ε-COP. The interaction between PIRH2 and ε-COP is affected by the presence of androgen, and PIRH2 in the presence of androgen promotes ubiquitylation of ε-COP in vivo. Furthermore, overexpression of the wild type of PIRH2 in prostate cancer cells causes downregulation of the secretion of prostate-specific antigen (PSA), a secretory protein in prostate epithelial cells and one of diagnostic markers for prostate cancer. Our results indicate that PIRH2 functions as a regulator for COP I complex.